C t Lin f I ti ii Planning Design Implementation
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Foreword The publication of "Fahrleitungen elektrischer Balmen" in English gives the international railway engineering community access to a work which, since its first edition in 1997, has achieved the status of a standard reference in German-speaking regions. A contact line is an essential component of all electric railway traction energy supply systems. It is the interface between fixed installations and moving energy consumers, i. c. vehicles. The contact line designs must be adapted to the respective technical and operational requirements of the different railway electrification systems, the diversity of which has broadened considerably especially with the development of high-speed railway traffic. A thorough analysis of these requirements and corresponding satisfactory design measures are prerequisites for reliable and economical operation of contact lines and of railways in general. The structure and contents of this book reflect this systematic approach: It contains a detailed description of all existing alternating--current and directcurrent systems, the basic requirements that these impose on contact lines and the essential characteristics of the two basic designs: overhead contact lines and contact rails. The interaction of current collectors and contact lines and the issue of interference with railway-owned and third-party installations are dealt vvith in special chapters. The mechanical and the electrical parameters of contact lines, structural design solutions, project planning, constrnction and operation, including maintenance, are also discussed in detaiL In addition, the lists of available relevant international, European and national standards, as well as the regulations of railway operators and railway associations included in the appendix of the book are very useful. In this context, I would like to draw the readers' attention to the evolving technical and operational harmonisation of European railway companies spurred on by the EC directives on interoperability. In this process, "Technical Standards for Interoperability" which establish binding rules on the essential parameters, have been drawn up inter alia for the energy supply sector, where contact lines are dealt with specifically. The parameters, which are to be standardised in this way, have to be chosen carefully, taking technical and economic factors into consideration. I am very pleased to report that the compendium of knowledge provided by this book, "Contact Lines of Elc\ctric Railways", was a great assistance in fulfilling this task. I would like to congratulate and thank the authors and publisher for their initiative by offering this important work to tlwir professional colleagues all over the world
Paris, October 2001
Wcn1,er Breit;li'llfJ
Deputy Chief Exerntive, UlC, Paris
Preface to the first English edition The first edition of "Fahrleitungen elektrischer Bahnen" (Contact Lines for Electric Railways) was published in German in 1997 by B.G. Teubner-Verlag Stuttgart. The first edition was out of print quickly, so a second, revised edition was published in 1999. The co-authors of this book, Professor Dr. sc Anatoli Ignatjewitsch Gukow and Dr. sc. Peter Schmidt, died unexpectedly in 1999 and 2000, respectively. Both had essential roles in the production of the German edition. There were no comparable works available and the book enjoyed wide distribution and attracted great interest, even in non-German-speaking countries instigating the need for translations in other languages. Prior to the first English edition, substantial parts of the book were revised and adapted to include international overhead contact line designs. The revisions were based on international standards as published by IEC and EN. Advice and comments from readers were also incorporated. More attention was paid to 50 Hz railways and local public transportation systems. New calculation methods, upto-date examples of completed electrification projects and recently developed overhead contact line components have also been included. The aims of the book are explained in the preface to the first edition, which also appears in this edition. The world-wide spread of high-speed railway systems, the need to ensure inter operability and the expansion of local public traffic systems are intensifying the demands made on electric railways, the qualifications of staff involved and supporting documentation. So, this edition especially aims to describe the theoretical principles underlying overhead contact lines and to offer possible solutions for their application, whilst taking current international developments in this complex field into consideration. At the same time, the book is intended as a co-operative contribution with projects carried out in parts of the world where German is not spoken. The authors would like to thank the Transportation Systems Electrification Department of Siemens AG and especially the heads of this department, Dr. Werner Kruckow and Peter Schraut, who supported the preparation of the English edition. Beat Furrer of Furrer & Frey AG, Bern, Switzerland sponsored the preparation of the manuscript. The authors also thank the publishing company for its excellent technical facilities. Thanks are extended to Gernot Hirsinger for preparing the translation as well as Bela Jozsa, Norm Grady, Terry \,Vilkinson, John Allan and Jan Liddicut from Melbourne/ Australia, who edited the English version and ensured that the complicated subject matter was understandable to English speaking readers. The authors thank Dr. Wilhelm Baldauf of Deutsche Bahn AG and Dr. Egid Schneider at Siemens AG, who supported them with contributions to certain sections of this revised edition, and Michael Schwarz for desk top editing. The authors hope this book will promote co-operation amongst colleagues working in this field in as many countries as possible, and that it will contribntes to their mutual technical understanding. They look forward to readers' comments and their advice on the content and design of the book. Erlangen, Septernhcr 2001 Friedrich K1,cj{lzng, Rainer Puschm,11,nn, A:i:el Schrm,eder
Preface to first German edition In 1866, the German engineer and entrepreneur Werner von Siemens discovered the dynamoelectric principle, which opened the possibility for generation and application of electrical energy to the extent we know today. Using this principle, he also built the first electric locomotive for railways. This locomotive, with three coaches, was operated for the first time at the Berlin Trade Fair on May 31, 1879. As is well known, the storage of the necessary quantities of electrical energy for other than low powered engines, with onboard batteries, on vehicles is not feasible. Therefore, to use electricity requires a continuous connection between the power station and the locomotive. The first electric train required a power of 2,2 kW and was supplied by DC 150 V through the two rails of the track. Siemens also employed this technique in 1881 for the world's first electric tram in Berlin - Spandau, using a DC 180 V supply instead of DC 150 V. Unfortunately, this power supply system lead to accidents with horses being electrocuted when simultaneously touching the two rails whilst crossing the tracks. This method of transferring electricity was technically unsuitable for extended railway installations. Furthermore it was dangerous, especially at higher powers, as the horse example above shows. For continuing the tram service in Spandau, two contact wires above the rails were introduced in 1882. A double contact trolley busway was suspended from the wires above the track and towed along by a flexible cable, attached to the tram. The trolley was often derailed and the system proved to be too unreliable for commercial operation. However, in 1889 the German engineer Reichel from Siemens first suggested the use of a bow current collector instead. This collector enabled the current to flow from a single wire above the tracks to supply the tractive units and return through the rails. This was the major breakthrough in the development of overhead contact lines to be suited for the transmission of power to running trains in long-term operation. The first electrically operated railways used DC power supply systems and series motors, which were well suited to railway operation. However, these systems had the disadvantage of vehicles having to be supplied with the low operating voltage of the motors, resulting in limited performance and large conductor cross-sections. Consequently, there were early efforts to use AC systems for railway power supplies, either three phase AC or single phase AC. In addition, research was being carried out to find ways of making the transmission voltage independent of the motor voltage, by allowing the currellt to be transformed on board the vehicles. Eventually, AC voltage networks for raihvays could be implemented by using a frequency lower than that used for public electricity distribution. The use of reduced-frequency AC networks enabled to produce simple and reliable train motors. The 16, 7 Hz frequ<'ncy was used for the MurnauOberamrrn~rgau and Bitterfeld-Dessau lines in Germany. Subsequently, in accordance with the 1912/1913 agreement between the Prussian-Hessian, the Bavarian and the Baclian Stat<~ Railways, this frequency was adopted throughout Germany. It was also agreed to 11S<' a. supply nllt.a.ge of E> kV. an ov<~rhea.d rnntact wire h<~ight of 6,0 m and
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Preface to first German edition
a current collector width of 2,10 m. The development and application experience of power electronics eventually opened the way for the use of industrial frequency power supplies in railway systems. Therefore, today completely new railway systems operate mainly on 50 or 60 Hz frequency and 25 kV power supplies. Approximately 25 years ago, railway energy supply entered a new era, wherein the motor voltage became independent of the supply voltage. Since then, advantageous three-phase current technology has been used for the traction motors and a differing and convenient frequency and voltage system used for power transmission. Due to these developments, the electric railway has progressed technologically to levels almost utopian 20 years ago. Operating speeds have increased to 300 km/h and will soon rise to 350 km/h. In 1988 the Intercity Express (ICE) train of the Deutsche Bundesbahn (DB) reached a maximum speed of 407 km/h , surpassing for the first time the 400 km/h mark on railway tracks. Later in 1990 the TGV-A of SNCF broke the world record by reaching a speed of 515 km/h, untouched up to now. In both these success stories, the decisive aspects were the reliable supply of high electric power through the overhead contact lines and pantographs. These developments in railway engineering ran parallel with increasing train speeds and powers to be transferred to the trains. The progression of overhead contact lines of German Railways (Deutsche Bahn) designed for speeds of 160 km/h, 200 km/h, 250 km/h and 330 km/h illustrate this. In a railway energy supply system, the overhead contact lines serve not only as distribution lines but also as sliding contacts to the pantographs of the vehicles. They must perform their duties reliably under extreme weather conditions up to the highest speeds. Stringent electrical and mechanical requirements are applied in order to accommodate current flows of thousands of amperes through the contact points. The numerous dynamic criteria gain importance as speed increases. The spatial separation of supply and return current paths can result in various forms of interference to other systems and risk to people. In contrast to other rail engineering components, the overhead contact lines can not be designed redundantly because of technical and financial considerations. This is why overhead contact lines play such a major role in determining the reliability of railway operation, particularly since often operation at the upper limits of current transfer and speed has to be performed. Railway electricity supply systems and overhead contact lines in particular, are major components of railway systems and represent long-term economic assets involving large financial investments. Thus expert design of contact line components, conscientious planning of each individual installation and careful erection using well developed and tested components are essential. This, together with correct operation and maintenance will guarantee a long and durable life for the installation. As the technology developed, the literature expanded. In 1929 Haring dedicated one special chapter to "Overhead contact lines" in his book "Elektrische Bahnen (Electric railways)" for German readers. In 1938, Sachs discussed Overhead Contact Lines for the first time in his book "Ortsfeste Anlagen der elektrischen Zugfoerderung (Fixed installations of electrical railway operation)". It addressed both dectrical and mcchauical iwrspectives in detail and comprehensively. Later, in 1971 Siiherkriih dealt rnaillly with
Preface to first Gerrna11_e_di_ti_01_1_ _
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mechanical aspects of power transmission in his book "Technik der Bahnstromleitungen (Engineering of overhead power lines for railways)". The VEM Handbook "Energieversorgung elektrischer Bahnen (Power supply for electric railways)", published in 1975 also focused on electrical issues of power supply. In "Oberleitungen fiir hochgespannten Einphasenwechselstrom in Deutschland, Osterreich und der Schweiz (Overhead contact lines for single-phase high-voltage alternating current in Germany, Austria and Switzerland)", published by Schwach in 1985, the evolution of 16,7 Hz overhead contact lines in Central Europe, was described. The book is technically sound and is a rich source of information. As running speed and electric power requirements have increased with high-speed rail transport, overhead contact lines have had to perform to new standards which were not significant at the time these books were written. The dominant importance of the dynamic interaction of overhead contact lines and pantographs, the rating of the systems for very large currents and those safety aspects resulting from high loads and new types of superstructure need to be mentioned as does the reduction of energy losses, corrosion-resistant and easy-to-maintain design, all of which play important roles in regard of reducing costs for operation and maintenance. These issues have encouraged the authors to present a current reference book on overhead contact lines for electric railways, covering the basics of planning, design, construction and operation . The book discusses the progress achieved in recent years in understanding power transmission, including modern planning and design methods for overhead contact lines. The book is a reference for planning and design of mechanical, electrical and thermal aspects of contact line components and their implementation. It is written for interested students, early career and experienced engineers from railway companies and also contractors interested in the subject. The restructuring of all technical standards used within the European Community also has ramifications for overhead contact lines for electric railways. Although the restructuring is well under way, it has yet to be completed fully. The book includes a summary of all standards related to or concerned with overhead contact line installations, as at July, 1997. Only those standards that are referrenced in the book have numbers in the text. The reader can cross-reference the title of a respective standard from Appendix 1. Appendix 2 is a glossary of abbreviations used in the book. This book was prepared with the kind support of the Transportation Group of Siemens AG, Erlangen, the Institute for Electrical Transportation Systems at the Technical University of Dresden and the Institute of Railway Technology, Dresden Branch. The authors thank the above organisations for their support, without which this book would not have been possible. The authors also wish to thank DL-Ing. K. lVIiiller, Dr.-Ing. A. Kontcha, DipL-Ing. R. Seifert, Dipl.-Ing. M. Semrau and DipL-Ing. (FH) K Dollack for their contributions, advice and suggestions for presentation of the subject. Dr. rer. nat. H. Worm assisted with manuscript procluctiou attd provided many useful suggestions. The authors also thank M. Schwarz and D. Sdilcg!, who prepared substantial portions of the manuscripts for printing.
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The publisher was very generous to the authors regarding the size and design of this book. The authors dedicate this book to the Transportation Systems Group of Siemens AG, on the occasion of the 150 th anniversary of Siemens AG, the Siemens company, whose founder and employees made fundamental and essential contributions to this particular subject. Moskow, Erlangen, Dresden, September 1997
A natoli lgnatjewitsch Gukow, Friedrich Kiej]ling, Rainer Puschmann, Axel Schmieder, Peter Schmidt
Contents 1 Traction power supply systems 1.1 Functions of traction power supply 1.2 Traction power supply networks . . . . . . . 1.2.l Types of traction power supply systems 1.2.2 Basic structure of the traction power supply 1. 2. 2 .1 Traction power generation . . 1.2.2.2 Traction power distribution . . . . . . 1.2.3 Direct current traction networks . . . . . 1.2.4 AC 16,7 Hz single-phase traction networks 1.2.4. l Traction power generation . . . . . . . 1.2-4.2 Types of 16,7 Hz traction power networks 1.2.5 50 Hz single-phase AC traction networks . . . 1.3 16,7 Hz traction power supply of the German Railway (DB) 1.3.1 Energy generation . . . . . . . . . . . . . . . . . . . 1.3.2 Energy transmission and contact line supply . . . . . 1.3.3 Standard 16,7 Hz substations of the German Railway 1.3.3.1 Function and types of standard substations 1.3.3.2 110 kV open air equipment 1.3.3.3 15 kV indoor equipment 1.3.3.4 Auxiliaries' supply . . . . . 1.3.3.5 Protection . . . . . . . . . 1.3.3.6 Supervisory control and data aquisition system (SCADA) 1.3.3.7 Buildings and supporting structures 1.3.4 Power system control . . . . . . . . . . . . . . . 1.3.4. l Development, functions and design . . . . . l.3A.2 Local control units and remote control lines l.3A.3 Remote control technology of the SCADA 1.3.4.4 Converters, remote control nodes and satellite control centres 13.4.5 Master control centres . . . . . . . . . . . . . . . . . . . . 1.3.4.6 Transmission control and network command centres .. . 1.4 AC 25 kV 50 Hz traction power supply of the j\1Iadricl-Se,·ille line 1. 4.1 Line supply and connection . . . . . . . . . . . 1.4.2 Substations and thr.ir components . 1.5 DC 750 V traction pow<~r supply of the Ankaray underground railway system. 1.5.1 Linc snpply and switching .. 1.5.2 Substalions and cornponents. l.G Reforcnc<'s
31 31 31 31 34 34 35 36 37 37 38 40 43 43 43 44 44 45 48 50 51 53 56 57 57 58 59 60 60 61 61 61 63 64 64 65 67
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2 Requirements and specifications 2.1 Requirements on contact lines 2 .1.1 General . . . . . . . . . . 2.1.2 Mechanical Requirements 2.1.3 Electrical requirements . . 2.1.4 Environmental requirements . 2.1.5 Requirements of operation and maintenance 2.2 Requirements resulting from the track, line and operating conditions 2.2.1 Requirements and demands made on contact lines . 2.2.2 Operating requirements . . . . . . 2.2.2.l Main-line, long-distance traffic . . . . 2.2.2.2 Local-area traffic . . . . . . . . . . . . 2.2.3 Requirements due to track-related factors 2.2.3.1 Main-line, long-distance traffic . . . . 2.2.3.2 Urban and local-area traffic . . . . . . 2.2.4 Requirements due to the railway line location 2.2.4.1 Main line long-distance traffic . 2.2.4.2 Local-area traffic . . . . . . . . 2.2.5 Requirements relating to the gauge 2.2.5.1 Main-line long distance traffic . 2.2.5.2 Local-area traffic 2.3 Climatic conditions 2.3.1 Temperatures . . 2.3.2 Wind velocities . 2.3.3 Ice accumulation 2.3.4 Active substances in the air 2.3.5 Lightning voltage surges . . 2.4 Specifications due to the pantograph 2.4.1 Design and functions . . . . . . . 2.4.2 Properties of collector strips . . . 2.4.3 Contact forces between the pantograph and the overhead contact line 2.4.3.1 Basics for static contact force 2.4.3.2 Aerodynamic contact force . . 2.4.3.3 Dynamic contact force . . . . . 2.5 Specifications on reliability and safety 2.5.1 Standards . . . . . . . . 2.5.2 Loading and strength 2.5.3 Insulation co-ordination 2.5.4 Protection against electric shocks 2.5.4.1 General protect.ion against electric shocks 2.f>A.2 Protection against electric shocks by direct contact 2.5.4.3 Protection against electric shocks by indirect contact 2. 5.4.4 Protect.ion against dec-tric shocks caused by the 1rack potential 2 G Envinmnwnt.al compatibilitv .
69 69 69 70 70 71 71 72 72 72 72 74 75 75 76 76 76 77 77 77 80 83 83 84 86 86 86 87 87 90 91 91 92 93 94 94 94 95 97 97 98 99 101
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2.6.1 General . . . . . . . . . . . . . . . . . . . . 2.6.2 Environmental relevance of electric traction 2.6.3 Land Usage . . . . . . . . . 2.6.4 Nature and bird protection 2.6.5 Aesthetics . . . . . . . . . . 2.6.6 Electric and magnetic fields 2. 7 Physical characterisitics of materials in contact line installations 2 .8 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
102 102 103 103 103 104 104 107
3 Traction contact line systems and overhead contact line designs 3.1 Terminology . . . . . . . . . 3.2 Overhead contact line types . . . . 3.2.1 Basic characteristics . . . . . . 3.2.2 Wires and stranded conductors 3.2.2.1 Types of wires and stranded conductors 3.2.2.2 Contace wires . . . . 3.2.2.3 Steel wires . . . . . 3.2.2.4 Stranded conductors 3.2.2.5 Synthetic ropes . . . 3.2.3 Trolley-type contact lines 3. 2. 3 .1 Definition and application 3.2.3.2 Single-point suspension with fixed anchored contact wire 3.2.3.3 Pendant-type suspension with and without automatic tensioning 3.2.3.4 Bridle-type suspension . . . . . . . . . . . . 3.2.3.5 Elastic supports . . . . . . . . . . . . . . . . 3.2.4 Trolley-type contact line with stitch suspension . 3.2.5 Overhead contact lines with catenary suspension 3.2.5.1 Basic design . . . . . . . . . . . . . . . . . 3.2.5.2 Contact lines with droppers at the supports 3.2.5.3 Contact line with offset support droppers 3.2.5.4 Contact line with stitch suspension . . . . 3.2.5.5 Contact line with inclined suspension .. . 3.2.5.6 Contact line with elastic dropper elements 3.2.5.7 Contact line with auxiliary catenary wire, compound contact line 3.2.6 Horizontal catenary overhead contact lines 3.3 Conductor rails . . . . . . . 3.3.1 Third rail installations . . . . . . . . . . . 3.3.2 Types of conductor rail 3 3.3 Construction and operation of conductor rail installations 3.4 Overlwa,d conductor rail installations 3.5 Rdeu~t1ces ..
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109 111 111 112 112 112 114 114 11.5 115 115 115 116 116 117 117 118 118 118 119 119 121 122 122 123 124 124 126 127 129 132
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4 Design of contact lines and cross-span equipment 4.1 Overhead contact line equipment . . . . . . . . 4.1.1 Basic design . . . . . . . . . . . . . . . . . . . . 4.1. 2 Selection of the overhead contact line design . . 4.1.3 Selection of conductor cross sections and tensile forces 4.1.4 Selection of span lengths . . . . . 4.1.5 Selection of system height . . . . 4.1.6 Design of contact lines in tunnels 4.1. 7 Adoption of contact wire pre-sag 4.1.8 Selection of dropper spacing . . . 4.1.9 Use of a stitch wire . . . . . . . . 4.1.10 Selection of tensioning section length 4.1.11 Design of connected and insulated overlaps . 4.1.12 Design of overhead contact line equipment and its components . 4.1.12.1 Configuration of overhead contact line equipment 4.1.12.2 Midpoint anchors . . . . . . . . 4.1.12.3 Automatic flexible tensioning-. 4.1.12.4 Fixed terminations . . 4.1.12.5 Dropper. . . . . . . . 4.1.12.6 Electrical connections 4.1.12.7 Electrical sectioning . 4.1.12.8 Design of neutral sections and phase separations 4.2 Cross-span equipment 4.2.1 Introduction 4.2.2 Hinged cantilevers 4.2.3 Cantilevers across several tracks . 4.2.4 Head-spans . . . . . 4.2.4.1 Application . . . . . . . . 4.2.4.2 Design principles . . . . . 4.2.4.3 Detailed structural design 4.2.5 Portal structures . . . . . . . 4.2.6 Contact line pull-offs . . . . . 4.2.7 Cross-span equipment in tunnels 4.3 Traction power lines . . . . . . . . . 4.3.1 Definitions . . . . . . . . . . . . 4.3.2 Routing and supporting of traction power lines 4.4 Signals for electric traction . . . . . . 4.5 Guards to prevent accidental contact 4.6 Components and elements . . . 4.6.1 Overhead line clisconnectors 4.6.2 Insulators . . 4.6.2.1 Purpose and loadings 4.6.2.2 Insulating materials . 4.G.2.3 Designs and applications
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135 135 135 137 138 139 140 141 142 142 14-3 143 148 149 149 150 151 154 155 155 156 157 159 1-59 160 164 164 164 165 166 167 169 169 169 169 171 172 173 173 173 175 17G 17G l 7G
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4.6.2.4 Electrical and mechanical rating 4.6.2.5 Sdection and application . 4.6.3 Clamps and connection fittings 4.6.3.1 Purpose and rating . . . . . 4.6.3.2 Materials . . . . . . . . . . 4.6.3.3 Overhead contact line equipment 4.6.3.4 Hinged tubular cantilever . . . . 4.6.3.5 Head span structure . . . . . . . 4. 7 Systemisation of the overhead contact lines and their components 4.8 Implemented contact line systems 4.8.1 Mass transit systems . . . . . . . 4.8.2 Main line systems . . . . . . . . 4.8.2.1 Overhead lines for DC 3 kV . 4.8.2.2 Overhead contact lines for AC 15 kV 16,7 Hz 4.8.2.3 Overhead contact line for AC 25 kV 50 Hz . 4.9 References . . . . . . . . . . . . . . . . . . . . . . . .
177 178 180 180 180 183 185 188 190 192 192 198 198 202 208 215
5 Calculations for overhead contact line equipment 5.1 Assumptions concerning loads and stresses 5.1.1 Basic principles . . . . . . . . . . . . 5.1.2 Dead loads . . . . . . . . . . . . . . . 5.1.3 Tensile forces and their components . . 5.1.3.1 Tensile forces acting on conductors and wires 5. 1.3.2 Components of the tensile forces acting on conductors 5.1.4 Wind loads 5.1.5 Ice loads . . . . . . . . . . . . . 5.2 Sag . . . . . . . . . . . . . . . . . . 5.2.1 Single trolley-type contact line 5.2.1.1 Supports at equal height .. 5.2.1.2 Supports at different heights 5.2.1.3 Catenary suspended contact lines . 5.3 Physical state change equations . . . . . . 5.4 Deflection due to wind . . . . . . . . . . . 5.4.1 Deflection due to wind on tangent track 5.4.2 Deflection due to wind and contact wire stagger in curves 5.4.2.1 Contact wire offset in still air . . . . . . . . . . . . . 5.4.2.2 Contact wire offset under wind load . . . . . . . . . . 5.4.3 Deflection of overhead contaet line equipment due to wind 5.5 Longitudinal spans and tensioning section lengths 5.5.1 Relevance of span and tension lengths 5.5.2 Maxinrnm possible spans . . . . . . . . 5.5.2.1 Significant p;-1rnmeters . . . . . . . 5.5.2.2 \\forking range of pantograph head 5.5 2.3 LaJ,<'.ral tt10\'()lll<'t1t. of the vehicle
219 219 219 219 221 221 224 229 231 232 232 232 233 234 236 240 240 241 241 242 243 247 247 247 247 248 248
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5.5.2.4 Contact wire limit position with deflection by wind 5.5.2.5 Determination of longitudinal span lengths 5.5.3 Calculating tensioning section lengths ( tension lengths) 5.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . .
250 252 253 255
6 Planning of overhead contact line systems 6.1 Objective and process . . . . 6.2 Fundamentals and initial data 6.2.1 General . . . . . . . . . 6.2.2 Technical requirements . 6.2.3 Planning documents 6.2.3.1 Introduction 6.2.3.2 New lines .. 6.2.3.3 Existing lines 6.2.3.4 Alterations . 6.2.3.5 Tracks and topography 6.2.3.6 Circuit diagram . . . . 6.3 Contact wire stagger and horizontal forces 6.4 Determination of span lengths 6.5 Tensioning section lengths 6.6 Overlapping Sections . . . 6. 7 Contact line above points 6. 7.1 Introduction . . . . . 6.7.2 Designation and drawing of track points 6. 7.3 Principles of overhead contact line wiring at track points 6.7.4 Fitting-free area . . . . . . . . . . . . . . . . . . . . . . 6. 7.5 Arrangement of intersecting contact line wiring at points 6. 7.6 Definition of supports for crossing contact ,vires at track points 6. 7. 7 Height of contact wires in points area . 6.7.8 Example for point wiring 6. 7.9 Tangential point wiring 6.8 Route obstacles for wiring 6.8.1 General . . . . . . . . . 6.8.2 Points . . . . . . . . . . 6.8.3 Signals and signal visibility 6.8.4 Railway crossings . . . . . . 6.8.5 Engineering structures . . . 6.8.6 Electrical separations at stations and on open track 6.9 Layout plan . . . . . . . . . . . . . . 6.9.1 Objective and information . . . . 6.9.2 Overhead contact line system symbols 6.9.;3 Contact line equipment supports and pole locations . 6.9.4 Single poles . G. 0 :> Ifrad-span strnd,ures .
257 257 260 260 260 260 260 263 265 265 265 266 267 273 274 276 277 277 277 281 281 282 284 287 289 292
294 294 295 295
295 296 300 300 300 301 :301 30G 307
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6.9.6 Multiple-track cantilevers 6.9. 7 Portals . . . . . . . . 6.9.8 Tunnel supports . . . . . 6.9.9 Electrical connections .. 6.9.10 Return current circuits and protective earthing 6.9.11 Signals for electric traction 6.9.12 Establishing layout plans . 6.10 Transverse profile diagram . . . 6.10.1 Objective and information . 6.10.2 Types of poles and their classification. 6.10.3 Pole geometry . . . . . . . . . . . . . . 6.10.4 Transverse switching lines, disconnectors on poles 6.10.5 Determination of pole lengths 6.10.6 Cantilevers . . . . . . . . . . 6.10.7 Pole and foundation selection 6.10.8 Head-span structures . 6.10.9 Portals . . . . . 6.11 Longitudinal profiles .. . 6.11.1 Contents . . . . . . . 6.11.2 Dropper arrangement 6.11.3 Contact wire height reductions 6.11.4 Traction power line longitudinal profile . 6.11.5 Minimum clearances to overhead lines and traction feeder lines 6.11.6 Traction power lines . . . . . 6.11.6.1 Introduction . . . . . . . 6.11.6.2 Line attachment to poles 6.11.6.3 Clearance verification .. 6.12 Project documentation . . . . . . 6.13 Computer supported configuration 6.13.1 Objectives . . . . . . . . 6.13.2 Structure and modules . 6.13.3 Data management . . . 6.13.4 Hardware and software . 6.13.5 Application 6.14 References . . . . . . . . . .
307 307 307 307 308 311 311 312 312 312 315 315 315 318 319 320 323 325 325 325 326 326 327 328 328 328 329 335 336 336 337 337 339 339 340
7 Cross-span structures, poles and foundations 7.1 Loading assumption 7.1.1 Introduction 7.1.2 PNmanent loads 7.1.3 Variable loads . 7.1.3.1 General .. 7.1.3.2 Wind loads 7.L3.3 k<, loads
341 341 341 341 342 342 342 344
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.. ·--·· ----·-·-----·--------- ··-------·------~C..c.con.tents
7.1.3.4 Simultaneous action of wind and ice . 7.1.4 Loadings due to erection and maintenance 7.2 Transverse support equipment and poles 7.2.1 Transverse support equipment, .. 7.2.1.1 Types of support equipment .. 7.2.1.2 Swivel cantilevers . . . . . . . . 7.2.1.3 Cantilever across several tracks 7.2.1.4 Flexible transverse support equipment 7.2.1.5 Portal structures 7.3 Poles . . . . . . . . . . 7.3.1 Types of poles 7.3.2 Loading assumptions 7.3.3 Structural design and materials 7.4 Rating of cross-span supports 7.4.1 Introduction . . . . . . . 7.4.2 Cantilevers . . . . . . . . 7.4.2.1 Loading and internal forces and moments 7.4.2.2 Rating based on Eurocodes .. . 7.4.3 Flexible cross-supporting structures . . . . . . 7.4.3.1 Introduction . . . . . . . . . . . . . . . . 7.4.3.2 Loading, internal forces and sag of head span wires 7.4.3.3 Height of installation, determination of pole lengths 7.4.3.4 Loadings and internal forces of cross-span wires . . . 7.4.3.5 Rating of head-span wires, cross-span wires and supports 7.4.4 Horizontal registration arrangements 7.5 Rating of poles . . . . . 7.5.1 Introduction 7.5.2 Determination of pole length 7.5.3 Loadings and internal forces and moments 7.5.4 Rating· of cross sections 7.5.4.1 Introduction 7.5.4.2 Lattice steel poles . 7.5.4.3 Double channel poles . 7.5.4.4 H-beam poles .. 7.5.4.5 Steel reinforced concrete poles 7.5.4.6 Deflection 7.6 Subsoil . . . . . 7.6.1 Introduction 7.6.2 Undisturbed soil 7.6.2.1 Classification 7.6.2.2 Non-cohesive, rolling soils 7.6.2.3 Cohesive soils . 7.6.2.4 Organic: soils 7 6.3 n.ock .
345 345 345 345 345 345 346 347 347 348 348 349 350 352 352 353 353 355 357 357 357 359 360 360 361 363 363 363 363 366 366 366 369 370 372 374 376 376 376 376 377 377 377 378
Contents 21 ~ = = - - - - - - - - - - -----··-·-·- " " " · - - - - - - - - - - - - - - - - - - - - - = =
7.6.4 Soil fill . . . . . . . . . . . . . . . . 7.6.5 Soil investigation . . . . . . . . . . 7.6.6 Methods of obtaining soil samples . 7.6.6.1 Introduction . . . . . . 7.6.6.2 Investigation boring .. 7.6.6.3 Investigation by probes 7.6.7 Probing . . . . . . . . . . . 7.6.7.1 Introduction . . . . . . 7.6.7.2 Driven probes in accordance with DIN 4094 7.6.7.3 Standard Penetration Test. 7.6.8 Evaluation of soil investigation 7.6.9 Soil characteristics . 7.6.10 Practical application 7.7 Foundations . . . . . . . 7.7.1 Basis of design .. . 7.7.2 Block foundations without steps. 7.7.3 Block foundations with steps 7. 7.4 Driven pile foundations 7.7.5 Anchor foundations. 7.8 Example . . . . . . . . . . . 7.8.1 Data of contact line .. 7.8.2 Design according to recent European standards 7.8.2.1 Loadings . . . 7.8.2.2 Design of pole 7.8.2.3 Cantilever . 7.8.3 Foundation 7.9 References . . . . .
378 378 378 378 379 379 380 380 380 381 381 382 382 385 385 385 388 391 395 397 397 398 398 399 401 403 405
8 Contact line designs for special applications 8.1 Introduction . . . . . . . . 8.2 Maintenance installations . . . . . . . . . 8.3 Tunnel seals . . . . . . . . . . . . . . . . 8.4 Separation between electrification systems 8.4.1 Introduction . . . . . . . . . . . . . . 8.4.2 System separation sections on open lines 8.4.3 Stations with two power supply systems 8.5 Movable bridges . . . . . 8.5.1 Introduction 8,5.2 Contact line design . 8.5.2.1 Folding bridges . 8.5 . 2.2 Swivelling bridges 8.5 . 2_.3 Lifting bridges .. 8.5.3 Electrical connections a.nd signalling 8.6 Lr~vel <'rossings of lines fod by differing power supply systems
409
409 409 411 412 412 412 414 415 415 416 416 418 420 422 423
22- - - - - - - - · · · · · - - - · - - · - - · · · - - · - - - - - - - - - - - - - - - - - - - - -Contents -
8.6.1 Crossing between mainline railways and tramways . 423 8.6.2 Crossings between light-rail and trolley bus lines 424 8. 7 Contact line design above level crossings . . . . . . . . 426 8.7.1 Arrangements for standard height transports 426 8. 7.2 Arrangements for oversize transports with permanently increased contact wire heights . . . . . . . . . . . . . . . . . . . . . . 427 8. 7.3 Arrangement of gaps within the overhead contact line . . 428 8. 7.4 Temporary lifting of contact line by movable cantilevers 429 8.7.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . 429 8.7.5 Temporary lifting or removing of the contact lines by manual procedures431 8.8 Container terminals, loading and checking tracks, railway lines in mines . 432 8.8.1 Swiveling contact lines . . . . . . . . . . . . . . . . . . . . . . . 432 8.8.2 Circuit diagrams for loading and checking tracks . . . . . . . . 433 8.8.3 Swivelling stopes and laterally arranged overhead contact lines . 434 8.9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436
9 Interaction of pantographs and overhead contact lines 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 Technical principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.1 Propagation of transversal impulses along the length of a contact wire under tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.2 Behaviour of the taut contact wire when subjected to a constant force applied at a point moving along it . . . . . . . . . . . . . . . . . . . . 9.2.3 Contact wire uplift at high speeds . . . . . . . . . . . . . . . . . . . . 9.2.4 How a concentrated mass reflects transversal impulses travelling along a contact wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.5 How a dropper reflects transversal impulses travelling along a contact wire . . . . . . . . . . . . . . . . . . . . . . . . 9.2.6 Doppler factor . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.7 Natural frequencies of an overhead contact line . . . . . . . . . 9.2.8 Dynamic characteristics of typical overhead contact line designs 9.3 Simulation of interaction of overhead contact lines and pantographs 9.3.1 Purpose and objectives . . . . . . 9.3.2 Model ofthe pantograph system 9.3.3 Contact line system models . . . 9.3.3.1 Basic considerations . . . . . 9.3.3.2 Modelling with the aid of the finite-element method [0.16] 9.3.3.3 Analytical solution in the frequency area [0.1-!] . . . . . . 9.3.3.4 l'viethocl using frequency-dependent finite elements . . . . 9 3 3.5 J\iioclelling on the basis of d'Alambert's wave equations [0.5] ~L~J .. J Overhead contact line installation models using frequency-dependent finite elements . . . . . . . . . . D.:3A. l fviathematic:al description . . . . . . . C)_:1 °1 2 Natmal frequ<'llCV ndrnlation cxan1ple
439
439 439 439 441 442 445 447 449 451 451 453 453 454 456 456 457 457 457 458 458 458 162 0
(
l
...C.C-"-o=nt=--=e=nt=s_ _ _ _ _ _ _ _ _ _ _ _ _ ,,,__,__, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___:c2~3
9.3.4.3 Contact force calculation . . . . . . . . 9.3.4.4 Examples for contact force calculations . 9.4 Measurements an
463 465 466 466 468 468 468 472 475 476
10 Currents and voltages in traction power supply networks 10.1 Introduction . . . . , . . . . . 10.2 Electrical characteristics of corit.aJ·t li11es
517
479 482 484 484 486 486 487 487 487 487 490 492 492 494 496 498 499 499 499 502 504 507 507 509 509 511 512
517 517
24
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Contents -----
10.2.1 Basic relations . 10.2.2 Impedances . . . 10.2.2.1 Components 10.2.2.2 Resistance per unit length . 10.2.2.3 Inductance per unit length 10.2.2.4 Impedance per unit length. 10.2.2.5 Measuring the impedances of contact lines . 10.2.2.6 Calculated and measured impedances per unit length - comparisons 10.2.3 Track-to-earth leakance per unit length . 10.2.4 Capacitances per unit length . . . . . 10.3 Voltage regulation in contact line networks 10.3.1 basic requirements . . . . 10.3.2 Basic principles . . . . . . 10.3.3 Voltage drop calculations 10.3.3.1 Introduction . . 10.3.3.2 Single-end feed . . . . 10.3.3.3 Double-end feed . . . 10.3.4 Other calculation algorithms 10.4 Operating currents . . . . . . . . 10.4.1 General . . . . . . . . . . . . 10.4.2 Traction currents of traction units 10.4.3 Currents in a contact line section 10.4.3.1 basic considerations . . . . . . 10.4.3.2 General-purpose railway lines . 10.4.3.3 High-speed and heavy-traffic railway lines 10.5 Contact line circuits . . . . . . . . . . . . . . 10.5.1 Basic requirements on contact line circuits . . 10.5.2 Ba.sic types of circuits . . . . . . . . . . . . . 10.5.3 Contact line installation circuits used by the German railways, DB 10.5.4 Disconnect.ors 10. 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . .
517 518 518 519 522 525 526 530 534 536 -538 538 539 541 541 541 543 546 548 548 548 548 548 549 551 552 552 553 555 560 560
11 Current-carrying capacity and protective provisions 11.1 Current-carrying capacity of electric traction contact lines 11.1.1 Electric traction power load . . 11.1.1.1 Power requirements . . . . . . . . . . . 11.1.1. 2 Railways for general traffic . . . . . . . 11.1.1.3 High-speed and heavy-duty railway lines 11.1.1.4 Short-circuit loads . . 11.1. 2 Current-carrying capacity . . . . . . . . . . 11.1.2_1 Introduction . _. . . . . . . . . 11.1.2.2 Differential equation describing the heating of contact wires 11. 1.:3 Current capacity in case of varying operational currents L1 1 :3. L Differential equation of contact line heating .
563 563 563 563 563 569 571 576 576 576 :i77 :i77
Contents
__
25
11.1.3.2 Parameters affecting the current-carrying capacity of a conductor . 11. 1.3.3 Current-carrying capacity of individual contact wires or conductors 11.1.3.4 Current-carrying capacity of overhead contact lines . . . . . 11.1.3.5 Current-carrying capacity of conductor rails . . . . . . . . . 11.1.3.6 Short-term current-carrying capacity and reference strength 11.1.3.7 Short-circuit current-carrying capacity 11.1.3.8 Fusing current . . . . . 11.1.4 Thermal design calculations . . . . . . . . 11.1.4.1 Maximum principle . . . . . . . . . . 11.1.4.2 Matching load and current-carrying capacity characteristics 11.2 Effect of the temperature on contact wire characteristics 11.2.1 Introduction . . . . . . . . . . . . . . . 11.2.2 Metallurgical principles . . . . . . . . . . . . . . . . 11.2.3 Effect of heating on the tensile strength . . . . . . . 11.2.4 Effect of exposure to increased heat on tensile strength 11.2.5 Heating and reduction of contact wire tensile strength at locations subject to increased wear and at connection terminals . . . . . . . . . . . 11.2.6 The tensile strength of contact wires at the contact wire collector strip interface . . . . . . . . . . . . . . . . . 11. 2. 7 Conclusions . . . . . . . . . . . . . . . . . . . . . 11.3 Contact line protection and fault location . . . . . . 11.3.1 Purpose of protective provisions for contact lines 11.3.2 Protective provisions for overhea
579 585 586 588 589 590 592 593 593 593 595 595 596 598 600
12 Current return circuit and earthing 12.1 Introduction . . . . . . 12.2 Terms and Definitions 12.2.1 Introduction 12.2.2 Earth . . . . . . . 12.2.3 Earth electrode . . 12.2.4 Soil resistivity and resistance to earth 12.2.5 Structure earth, tunnel earth, traction system earth . 12.2.6 Earth potential and rail potential 12.2.7 Touch voltage . . . . . . . . . . . . . . . . . . . . 12.2.8 Accessible voltage . . . . . . . . . . . . . . . . . 12.2.9 Overhead contact line zone and pantograph zone 12.2.lORetmn circuit. 12.2.11 Stray Current . 12.3 Basic principles . . 12.3.1 Return circuit . 12.3.2 Ra.ii potentials 12.3.2.1 Gell(~ra.l a.srwcts
621 621 622 622 622 623 623 623 624 624 624 625 625 625 626 626 630 630
603 605 607 608 608 610 615 61 7
26
Contents
12.3.2.2 Track-to-earth voltage in operational conditions .. 12.3.2.3 Track-to-earth voltage in the case of short circuits 12.3.3 Safety . . . . . . . . . . 12.3.4 Security . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.5 Stray current corrosion . . . . . . . . . . . . . . . . . . 12.3.6 Common features of and differences between AC and DC railways 12.3. 7 Measurements . . . . . . . . . . 12.4 Earth as a conductor . . . . . . . . 12.4.1 Soil resistivity and conductivity 12.4.2 Track-earth circuit . . . . . . . 12.4.2.1 General . . . . . . . . . . . 12.4.2.2 Track-earth circuit of DC systems 12.4.2.3 Track-earth circuit of AC systems 12.4.3 Earth electrodes in the vicinity of railways 12.4.3.1 Earth resistance of electrodes and pole earthing 12.4.3.2 Effective leakance per unit length . . . . . . . . 12.5 Direct-current traction systems . . . . . . . . . . . . . 12.5.1 Design of the return circuit and earthing installations . 12.5.2 Safety of persons . . . . . . . . . . . . . . . . . . . 12.5.3 Stray current protection . . . . . . . . . . . . . . . 12.5.3.1 General information on stray current corrosion 12.5.3.2 Effect of the polarity . . . . . . . . . . . . . . . 12.5.3.3 Protective measures against stray current corrosion 12.5.4 Stray current collecting nets . . . . . . . . . . . . . . . 12.5.5 Design of DC installations with respect to return circuit and earthing 12.5.5.1 Basic recommendations . . . . . . . . . . . . . . . . 12.5.5.2 Railway-owned earthing systems . . . . . . . . . . . 12.5.5.3 Earthing measures for the three-phase power supply 12.5.5.4 Traction substations . . . 12.5.5.5 Line sections in the open . . . . . . . . . . . . 12.5.5.6 Passenger stations . . . . . . . . . . . . . . . . 12. 5. 5. 7 Signalling and telecommunications installations 12.5.5.8 Depot and workshop area 12.5.5.9 Tunnels . . . . . . . . . . . . . . . 12.5.5.10 Lightning protection . . . . . . . . 12.5.5.11 Third party earthing installations . 12.5.5.12 Construction of DC earthing installations and provisions 12.5.5.13 Verification measurements . . . . . . . . . . . . 12.5.6 Practical experience with the Ankaray LRT system 12.5.6.1 Description of the project . . . . . . . . 12.5.6.2 Measurement of the resistance to earth . 12.5.6.3 Measurement of mil potentials . . . . . 12.!:i,6.4 Test of rail insulation . . . . . . . lLS.G.I:i Measurement of the potential between strnctme earth and earth
632 634 635 635 636 636 638 638 638 640 640 641 643 647 647 650 650 650 652 653 653 656 657 659 660 660 661 662 662 663 664 664 664 666 668 668 669 669 669 669 670 670 670 670
Contents
27
12.5.6.6 Current through short-circuiting devices in the stations . 671 12.5. 7 Maintenance . . . . . . . . . . . 671 12.5.8 Concluding recommendations . . . . . . . . . . . . . . 672 12.6 Alternating current traction systems . . . . . . . . . . . . 672 12.6.1 Design of the return circuit and earthing installations . 672 12.6.1.1 General . . . . . . . . . . . . . . . . . . . . . . . . 672 12.6.1.2 Current return through rails and earth buried return conductors 673 12.6.1.3 Parallel return conductors 674 12.6.1.4 Auto-transformers . . . . . . . . . . . . . . . . . . . 676 12.6.1.5 Booster transformers . . . . . . . . . . . . . . . . . . 677 12.6.2 Requirements of return circuit and earthing installations 677 12.6.2.1 Personal safety .. 677 12.6.2.2 Interference . . . . 680 12.6.3 Design of installations 680 12.6.3.1 Return circuit .. 680 682 12.6.3.2 Substations and stations . 12.6.3.3 At-grade sections . 683 12.6.3.4 Tunnel sections . . . . . . 683 12.6.3.5 Viaducts . . . . . . . . . 685 12.6.3.6 Depot and workshop area 685 686 12.6.3.7 Signalling and telecommunications systems 12.6.3.8 Third-party installations . 686 12.6.3.9 Lightning protection . . . . 687 12.6.3.10 Implementation . . . . . . . 688 12.6.3.11 Verification measurements . 688 689 12.6.4 Return current conductors and earthing systems used by the DB 12.6.4.1 Track and rail bonds . . . . . . . . . . . . . . . . . . . . . . . 689 12.6.4.2 Track release circuits, traction return current path and traction earthG91 12.6.4.3 Traction system earth connections of concrete structures 693 12.6.5 Current return and earthing for the Madrid-Seville AC 25 kV highspeed line . . . . . . . . . . . 694 12.6.6 Concluding recommendations G97 12.7 References . . . . . . . . . . . . . 698
13 Electric traction contact lines as emitters of electromagnetic disturbance 703 13.1 Introduction . . . . . . . 703 13.2 Coupling mechanisms .. 704 704 13.3 Interference p,uameters . 704 13.3.1 Overview . . . 705 13.3.2 Operating currents and short-circuit currents 706 13.3.3 Higher harmonics . 706 13.3.3.1 G(\neral . 706 13.3.3.2 Single-phase AC ra,ilwa_,·s
\}
28
Contents
13.3.3.3 Direct-current railways . . . . . . . . 13.4 Interference due to single-phase AC railways 13.4.1 Introduction . . . . . 13.4.2 Galvanic interference . 13.4.3 Inductive interference 13.4.4 Capacitive interference 13.5 Electric and magnetic fields in the vicinity of traction contact lines 13.5.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . 13.5.2 Effects of electromagnetic fields on human beings 13.5.3 Effect of fields on equipment . . . . . . . . . . . 13.5.3.1 Effects in general . . . . . . . . . . . . . . . . 13.5.3.2 Persons with implanted cardiac pacemakers . 13.5.3.3 Information technology and electronic data processing equipment 13.5.3.4 Electric railways as sources of radio-frequency interference 13.6 Conclusions 13. 7 References . . . . . . . .
710 711 711 711 712 717 718 718 718 719 719 722 722 722 724 725
14 Erection and operation 14.1 Basic definitions 14.2 Erection . . . . . . . . . 14.2.1 Principles . . . . . . 14.2.2 Production and testing standards for components 14.2.3 Construction and assembly work . . . 14.2.3.1 Introduction . . . . . . . . . . . . . . . . . . 14.2.3.2 Foundation and pole setting work . . . . . . . 14.2.3.3 Erection and adjustment of the overhead line supports and contact lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2.3.4 Installation of section insulators, cross-over contact lines, traction power supply lines and railway earthings . 14.2.4 Acceptance and commissioning . 14.3 Operate . . . . . . . . . . . . . . . . . . . . . . . 14.3.1 Training and instruction of staff . . . . . . . . 14.3.2 Electrotechnical conduct standards and service guidelines . 14.3.3 Switching . . . . . . . . . . . . . . 14.3.4 Irregularities and their recognition 14.4 Wear and ageing . . . . . . . . . . 14.4.1 Classification of components . . . . 14.4.2 Concrete poles and foundations . . 14.4.3 Steel poles, cantilevers and other support structures . 14.4.4 Traction power supply lines, messenger wires, droppers and connectors 14.4.5 Contact wires . . . . . . . . . . . . . 14.4.6 Insulators . . . . . . . . . . . . . . 14.4.7 Disconncctors and ~ectiou insulators l LG Mait1tc'rn1.11ce .
729 729 729 729 729 731 731 732
0
733 736 737 737 737 738 739 741 741 741 742 743 7-14 745 7°17
7-19 700
29
14.5.1 Scop<\ of maintance . 14.5.2 Reliability . . . . . . 14.5.3 Diagnostics .. 14.5.4 Statistical recording and analysis of faults 14.5.5 Corrective maintenance 14.6 Recycling and disposal . . . . . . . . . . . . . 14.6.1 Dismantling . . . . . . . . . . . . . . . . . 14.6.2 Suitable preparation and disposal of materials for recycling . 14. 7 Equipment for installation and maintenance 14.7.1 Tools and equipment . . . . . . . . . 14.7.2 Special vehicles . . . . . . . . . . . . 14.7.3 Measuring and diagnostic equipment 14.8 Life cycle consideration . 14.9 References . . . . . . . . . . . . . . . . .
750 750 755 759 761 762 762 763 763 763 766
Appendix 1: Standards and regulations
781
Appendix 2: Frequently used abbreviations
791
Index
795
774 774 777
1 Traction power supply systems 1.1
Functions of traction power supply
Electric traction has the function of safely transporting people and/or goods with the aid of electrified traction lines. The objective of the traction power supply is to ensure uninterrupted, reliable and safe operation of the electric traction vehicle. Under the technical aspect the traction power supply comprises the total of the fixed installations of the electric traction system [1.1, 1.2). The traction power supply is subdivided into traction power generation, traction power transmission, traction power feeding and traction power collection by mobile electric traction vehicles [1.3, 1.4]. In German Railway (DB), the traction power is supplied by AC 110 kV 16,7 Hz transmission lines as part of the traction power supply grid and the traction power distribution is performed by the traction power substations and overhead contact lines. The supply of mobile consumers through contact lines represents the significant difference between electric traction systems and the public grid. All traction power supply installations have to be designed, constructed and operated so that all previously mentioned general requirements can be fulfilled. This book is dedicated to contact lines which form the traction power feeding system. Contact line systems are subdivided into overhead contact line installations, third rail installations and overhead conductor rail installations. To comply with the requirements for reliable operation of electric traction, the following criteria are applicable, particularly with regard to contact lines: The provision of uninterrupted traction power at the pantographs of the traction vehicles. - The ability of the railway network to continuously absorb regenerated braking energy. - Compliance with specified and standardised quality parameters for the voltages available at the pantographs of electric traction vehicles. In addition to these requirements, consideration must be given to the fact that, the electrical loads on traction systems differ from the loads on the public energy supply grid because they are not only heavily dependent on time but also continuously varying in location of consumption.
1.2 1.2.1
'Traction power supply networks Types of traction power supply systems
Electricity powers the process of transportatio1t. When referring, to electricity, the term electn.cal enc1:r;y is usually applied throughout this book. \\'heu electricit.\ is
32
-
1 Traction power supply systems
DC3000V DC 1500 V or less
~
AC50Hz
~
AC16,7Hz
Figure 1.1: Traction power systems for mainline railways in Europe'.
fed through the contact line to electric traction vehicles, the electrical power has a greater significance. To distinguish between the various types of electrical energy supply for electric traction, it is usual to specify the type of current. Originally, direct current was used for electric rail transport. The reason for this was the extremely favourable, hyperbolic traction/speed curve of the series commutator motors used as drives in railway applications. On a global scale, over half of all electric traction systems still use direct current. The low voltage used is a disadvantage of existing direct current traction systems as it necessitates high currents to transmit the necessary traction power. At the beginning of the twentieth century, efforts were made to combine the traction advantages of the series motor with the transforming capability of alternating current. At that time, the objective was a single-phase AC series motor as a drive, which was to be fed with single-phase AC at the frequency of the public grids, in Germany and Central Europe that was 50 Hz. Because of the state of technical development at that time several problems arose including: the heavy commutator wear of the 50 Hz single-phase series motor by a frequencyproportional induced voltage in the single brush winding, the high and frequency-proportional, inducti,-e interference in cables running in parallel to the electric traction system, the unacceptably high values of voltage ctsnrnnetry in the 50 Hz three-phase ud,,vork supply caused by the traction pom~r single-phase supply_
I
I
1.2 Traction power supply networks _________________
33
Table 1.1: European voltage systems of electric railways according to EN 50163 Type of power supply Un Urnin2 Umin I Umaxl Umax2 Unrnx3 V V V V V V DC 600 V 1015 600 400 720 770 DC 750 V 750 1269 500 900 950 DC 1,5 kV 1500 1950 2538 1000 1800 DC 3,0 kV 3000 2000 3600 3900 5075 AC 15kV 16,7 Hz 15000 11000 12000 17250 18000 24311 AC 25kV 50 Hz 25000 17500 19000 27500 29000 38 746 Un Umin! Umin2 Umaxl Urnax2 Umax3
nominal voltage lowest permanent voltage lowest non-permanent voltage, maximum duration 10 min highest permanent voltage highest non-permanent voltage, maximum duration 5 min low-term overvoltage with a duration more than 20 ms
These problems could not be solved satisfactorily at that time. In Germany, the development efforts, led to single-phase AC supply with a frequency of 50 Hz/3 = 16,7 Hz, where the electrical energy is generated and distributed as single phase in a separate railway high-voltage network. Three German traction administrations introduced this type of traction power during the years 1912/1913. The system was also adopted by Austria, Switzerland, Norway and Sweden. This electricity system using single-phase AC 16,7 Hz has proven to be particularly powerful and effective for the electrical power supply of high-speed and high-capacity traffic. Figure 1.1 shows the traction power systems used for mainline railways in Europe. Initial experience with an AC 50 Hz traction power system was gained at the Hollentalbahn in Germany in approximately 1940. Due to the enormous progress made in the field of power electronics, AC 25 kV 50 Hz traction power is the type of electricity currently preferred in countries now starting to electrify their railways. These three, currently adopted frequencies in electric traction have different nominal voltages depending on their intended purposes. These nominal voltages and the permissible deviations from the nominal values are listed in Table 1.1. At the end of 1997, the length of the electrified long-distance traction lines ,vas over 182 000 km world-wide and was made up a~ follows: DC 1,5 kV, approximately 20 000 km, 11 % of total, DC 3 kV, approximately 70000 km, 38 % of total, AC 16, 7 Hz 15 kV, 33 000 km, 18 % of total and AC 50 Hz 25 kV, approximately 60 000 km, 33 % of total. For urban mass transit installations, mainly DC 600 V, 750 V, 1200 V or 1500 V are still in use.
i1
1 Traction power supply systems
34
~d~-L.._~ (·------,-----t--
Traction power plant
AC 3·-50 Hz, 380/220 kV gric1 Traction power generation
./ _ _ _ _ _ _ _ _ . L . . . . - ~ t - - - - , - ~ ~ ~
110 kV grid
.)
110 kV grid
~ (
10, 20, or 30 kV grid
~
.
I I I I I I I I I I I I I I I I I
Public p wer supply
I
Traction power sup~ly I I~
1.?:-
f~
I CO I E I Q)
-I
:!
110 kV grid 1-16,7 Hz
I
r-----J I I 1
Substation (50 Hz) Contact line
Traction power transmission
--- ----- ---Decentralised converter station (16,7 Hz)
I I I I I I I
------,
Traction power distribution
: I I I I ---1
Traction power feeding : and collection by
Runnin rail DC railway
mobile consumers Traction power supply 50 Hz
Decentralised power supply at 16,7 Hz
Central power supply at 16,7 Hz
Figure 1.2: Structure of the traction power supply systems [1.4].
1.2.2
Basic structure of the traction power supply
1.2.2.1
Traction power generation
Figure 1.2 depicts the common types of traction energy generation and the connection to the public grid. ·with DC and AC 50 Hz single-phase traction systems, the traction energy is drmvn from the public grid. The AC 15 kV 16,7 Hz systems are supplied from either the AC 16,7 Hz single phase transmission systems or decentralised converter stations are supplied from the public grid, e.g. in Sweden. As illustrated i11 Figure 1.2, the DC tractions systems are supplied from the threephase network with nominal voltages between (6 kV) 10 kV and :30 kV. Single-phase AC traction systems are usually connected to a 110 kV power grid. The well over one hundred AC 110 kV subnetworks of public power supply in Germany are not interconnected at the llO kV leveL This limits the short-cirrnit currents a11cl simplifies protc!ction of the networks i-\ll 110 kV ])O\H!r twtworks are supplied fr(Jlll a11cl connected
1.2 Traction power supply networks __
Energy from the public grid or from traction power transmission network
Traction substation single-phase AC tractions (SS)
Energy from the public grid
Rectifier substation (RSS)
Energy from the public grid
Decentralised rotating converter station (DRCS)
Energy frorn the public grid
(Decentralised) static converter station (DSCS)
Energy from other substations
Switching post (SP) coupling post (CP)
Supply of the contact line network through bus bars and circuit breakers
Figure 1.3: Types of substations used in traction power supply.
via the high-level interconnected grid with nominal voltages of 220 kV and 380 kV. As a result of this supply from the interconnected grid, all 110 kV power networks in Germany are synchronised. This fact is an essential condition for the implemented parallel operation of the decentralised traction power supply in parts of German Railway's (DB) supply system.
1.2.2.2
Traction power distribution
The functions of traction power distribution are to convert electrical energy supplied to substations into voltages and frequencies conforming with the nominal values used for traction power and the supply of this power to consumers. Substations (SS) of various types are used to supply traction power directly into the contact line installations. As indicated in Figure 1.3, there are: power transformer· stations, commonly referred to as substations (SS), which convert the voltage from the transmission network , at nominal frequency, into the nominal voltage of the contact line network as single-phase AC and supply the network with traction power. traction power rect~fi,er stations (DRSS), which convert the applied AC threephase electricity from the public grid into the required nominal voltage of the contact line network for direct current railways and supply this to the contact line installation, decentralised rotating converter :;.'.ations (DRCS) in which the three-phase energy of the AC 50 Hz public grid is converted with the aid of rotating machines into AC 16,7 Hz single-phase energy for the traction network and supplied to the contact line network after conversion to the corresponding nominal values, decentralised static converter stations (DSCS), which have the same function as the DRCS but by means of electronic power components instar.cl of rotating machines, switching posts (SP), also switching centres and coupling posts (CP) have the task of receiving the electrical energy from other substations ,vith characteristics according to the supply systcttt and feeding the contact line network or intercoll-
36 - - - - - - - -
1 Traction power supply _systems
SS"B"
Coupling post
Coupling post
Line to A
Line from C
Feeding sections Line from A
Line to C Feeding sections Direction of feeding A
Direction of feedin C
Section supplied by SS "B"
Figure 1.4: Mainline section supplied by a substation.
necting different sections of contact lines and switching these sections on or off. Figure 1.4 shows an example of power distribution by a substation in a mainline traction. Their function is to secure the supply of electrical energy to all trains passing through the substation supply section. The substation supply section, also known as the feeding section, designates the total of all contact line sections supplied by a substation in regular operation mode. A neutral section is a section of contact line which isolates adjacent feeding sections in such a way that they cannot be bridged by the pantographs of electric traction units. Some traction operators, create neutral section units with a coupling post (CP). CP use circuit breakers to facilitate longitudinal and cross-coupling of contact line sections to reduce voltage drops and losses in the contact line network. In overhead contact line networks, CP and switching posts (SP) connect substation supply sections during normal operations. This facilitates a secured return of the generated braking energy in systems designed for this operational mode. Switching sections and cirwit groups within the substation supply sections can be electrically separated by air insulated oYerlaps or section insulators, which are bridged by disconnectors during normal operation and may be bridged by the pantographs of the traction vehicles.
1.2.3
Direct current traction networks
Today, on a global scale over half of all electric railways adopt direct cu,rrent f;rnctwn. In mass transit systems, maximum nominal voltages of up to 1500 V are used because of the potential danger by higher voltages. The mu::;L common voltages are 750 V and 600 V. The distance between substations varies frurn 1,5 to 6 km, On some longdistance, DC 1500 V and DC 3000 V ra.ihrn,·s the substation spacing can be up to 20 km. Tlw poW(!r ratiug of direct <·urr<~nt. substMions ,ari<'s fl (>111 J to 2 j\[\\' for trn.11t\\'cWS
1.2 Traction power supply networks
37
Rectifier substation Medium-voltage Rectifier switching substation 3·-~ 50 Hz 20 kV
Direct current switching substation Contact line terminal neturn line + 825 V +(660 V)
I-
I
I-
I
Ground level cable distribution boxes Negative Positive terminal
from public grid (two feeders)
lo contact line
Figure 1.5: Direct current traction power supply system of a tramway.
and up to 10 MW in mass transport and main line systems. The three-phase voltage supplied from the three-phase public grid is converted at the rectifier substation into direct current at the nominal voltage of the contact line network. Previously, six-pulse current transformers were used but now, mainly twelve-pulse transformers are used for rectifiers. The switching components in rectifier substations are turnkey units usually designed for load class VI to EN 60146-1-3. Figure 1.5 shows the basic design of a direct current traction supply of a tramway. In the design and operation of direct current railways, special attention has to be paid to the problems of traction current return to minimise the hazard of stray current corrosion. These problems are addressed separately in clause 12.4.1.
1.2.4
AC 16, 7 Hz single-phase traction networks
1.2.4.1
'fraction power generation
Single-phase AC with the special frequency of 16, 7 Hz is generated by special singlephase generators. The physical relationship f = p · n exists between thr. frequency .f, number of pole pairs p and revolutions n of a generator. The lowest possible number of pole pairs is 1. Therefore, the highest speed at which a 16, 7 Hz generator can be operated will be n 16,7 · s- 1 or luOO · min- 1 . A 16,7 Hz generator therefore runs at one third the speed of a 50 Hz generator under otherwise equal conditions. However, the power P and the revolutions n arc linked to the moment M in the following manner: P = 11! · n. Comparing 50 Hz and lG,7 Hz generators, a moment three times higher would be required to achieve the same power at 16,7 Hz. Three times the moment means three times the size. The generators of the public grid are thre('-phase generators. The generators used in the Ln-ic-tion power supply with a frequency of lG,7 Hz are single-phase generators. Due to the lack of two windings, the laminated stator rnre is used less efficiently at lG,7 Hz bv ,\ factor of /3. A lG,7 Hz sittglc-p!tas<' g('tterat.or is therefore principally :3 · ./3 ~ !\'.2 tittt<~s larger than
I Traction power supply systems
38
pp
,JPP 110 kV 16,7 Hz overhead line system
ccs
PP power plant (railway-owned)
pp
JPP joint power plant CCS central converter station SS substation
Figure 1.6: Basic structure of central traction power supply.
a 50 Hz three-phase generator of the same power. Practical values lie around 4,5. The largest 16,7 Hz single-phase generator with a nominal power of 187,5 MVA therefore corresponds in size to an 850 MVA generator of the 50 Hz three-phase public grid. If 16,7 Hz single-phase generators are driven by motors supplied from the 50 Hz threephase network, this type of machine combination is designated in the traction power supply as a rotating converter. Regarding the frequency ratio of 50 Hz to 16, 7 Hz, elastic and rigid converter are discerned. Elastic converters are also designated as asynchronous-synchronous converters. By using a variable-frequency and, thereby, revolution-variable drive of the single-phase generator driven by an asychronous motor, it is possible to use elastic converters in parallel operation with traction pmver plants. Elastic converters are used to cover load peaks in centrally supplied networks of the DB. The power of elastic converters lies between 10,7 and 50 MVA. Rigid converters are synchronous-synchronous converters. In DB's decentralised network section, the single-phase power with a frequency of 16,7 Hz is generated in decentralised rotating converter stations (DRCS) with the aid of synchronous-synchronous converters, their nominal power being 10 l\lIVA.
1.2.4.2
Types of 16,7 Hz traction power networks
Two kinds of lG,7 Hz single-phase power supply have evolved in Europe. The central traction power supply (s<~e F'igure 1.6) has existed in Germany, Austria, Switzerland since 1913 and later in Norwav and can he characterised by: Power genc~ration using IG,7 Hz single-phase generators iw,1allecl in l1ydrodec-tric, t,IH!rtlli\l il!HI 1111dc,,11 p(Jwer plants n11d drin'n by wa.t.<'r 01 st<',1111 tu1hirws Tliis
1.2 Traction p9_wcr_:9.1_1pply _net.works _______
------ -
-------
____________________ 39 ___::_::__
3-50 Hz 110 kV
Synchronous generator
Synchronous motor
1-16,?Hz 15kV
Figure 1. 7: Design of a decentralised rotating converter station with synchronous-synchronous converters, i.e. rigid converters.
means of generating electrical energy is known as primary energy generation. Transmission of electrical energy by a 110 or 132 kV overhead line net-work with a nominal frequency of 16,7 Hz from the power plants to the substations. This single-phase network mostly incorporates two circuits and has a feed and return conductor for each system. Distribution of single-phase electricity in railway substations, where the voltage is converted from 110 kV or 132 kV to the nominal voltage of the contact line installation of 15 kV. Feeding of the single-phase 16,7 Hz energy through section circuit breakers in the substations to the individual feeding sections of the contact line installation. The most significant property of the decentralised traction power supply (see Figure 1.7), which has been operated since 1926 in Sweden and since 1968 in a network section of former Deutsche Reichsbahn (DR) in East Germany, since 1993 DB, is the existence of decentralised rotating converter stations (DRCS). The DRCS embodyies two tasks : Generation of single-phase power with a nominal frequeancy of 16,7 Hz and - Feeding of the single-phase 16, 7 Hz energy through section circuit breakers in the substations to the individual feeding sections of the contact line installation. The two types of single-phase 16, 7 Hz traction power networks have different parameters which are compared in Table 1.2. An overall summary slw-ws that both the central and the decentralised traction power supplies are able to supply trains with electricity safely, n"liably and with the required quality parameters. Over eighty years of electric traction transport on 20 000 km of centrally supplied traction lines and over seventy years of electric traction on 13 000 line kilometres supplied with 16,7 Hz electrical pavver from decentralised equipment prove the dependability of both types of 16,7 Hz power supply. Due to the high, short-term load peaks in the DRCS, high demand rates are currently paid in Germany for the energy taken from the AC 50 f-J,1, three-phase network. This economic disadvantage of the energy in cou1parison with 16,7 Hz energy generation and transmission in the 110 kV ncLwork has l<-xl to planning of extending the central supply of the DB.
40
1 Traction power supply systems
Table 1.2: Comparison of central and decentralised traction power supplies. Connection of the overhead contact line system Voltage stability of the substation bus bars Substation spacings
Provision of redundancy
Central supply Parallel operation of adjacent substations
Decentralised supply Parallel operation of adjacent converter stations
Droppmg " of the voltage to 0,8 times the nominal voltage at double the nominal load Shorter than in decentralised because of dropping bus bar voltage
Constant bus bar voltage at all loads
Compensation of load peaks through the 110 kV network, single transformer operation possible
Large load peaks increase the energy price, single-converter operation only possible with switching of converter characteristics
Installed power
Longer than in central because of canstant constant bus bar voltage
No difference Decentralised station
Reserve units
Central
Efficiency
0,91
Short-circuit currents in the overhead contact line network Availability Reactive power requirement in the traction network
Up to 45 kA
Higher
Lower because of absence of 110 kV overhead power lines
Line length 110 kV traction network Power losses in 110 kV network Generation
Around 1,3 times substation spacings Twice as high as in three-phase lines at equal transmitted power In large units with high efficiency
Around 0,05 times converter station spacings
1.2.5
in
converter
0,91 Up to 25 kA No difference
In small units with lmYer efficiency than in case of central generation
50 Hz single-phase AC traction networks
The electrical energy required for the operation of AC 50 Hz single-phase traction networks is obtained from one phase of the 50 Hz three-phase network of the public energy supply. This single-phase loading of the three-phase network causes unballance in the voltage and current of the three-phase network. The current unballance has only a minor effect on the generators, whereas the voltage unballance has serious effects on the consumers. The voltage unballance 11,u is inversely proportional to the short-circuit power St of the three-phase network. If the traction power Sc to be drawn from one phase of the three phase network is known, then the voltage unballance in the three-phase network at the point of supply is given ·with sufficient accuracy by: (LI)
1.2 Traction powersupply netwmks ..
L1 L2 L3
§
[23
r;i
CJ
SS1
a)
L1 L2 L3
SS1
q
SS2
qss2 H
Cr?·· _=c= __.___
Contact line Track
c~
L1 L2 L3
t~[;tj
SS3
[;:d
H
b)
SS3 Contact line Track
I
Threephase transformer
Contact line Track
V switching Contact line _ _ _ _ _ _ _ Track
c)
L1-,------------i-----------i--L2-+----,.--------.---.i--------+-....---L3-+---t--.-------+-----,--.i---------,---+-t---
H__.._a_ _ _ _a_____--+H_.__b_ _ _ _b_.__-+H a Contact line d) - ~ - - - - - - - ~ - - - - - - - ~ - - T r a c k C
____,,J,-- Phase separation
C
41
§
6
t:J q
----- -·--·-----· ·---
C
Figure 1.8: Alternatives of connecting 50 Hz single-phase traction power substations to the three-phase network. a) Connection without compensation for unbalance. b) Cyclically changed connection, thereby indirect compensation of the unbalance. c) 120° connection for direct compensation of the unbalance. d) Cyclically changed connection of parallelly operating substations with direct compensation by 120° switching (Russian state railway traction systems)
With short-circuit power varying between 700 MVA and 3000 MVA in the 110 kV threephase network and powers of the traction power substations up to 40 MVA, high values of voltage unballance are to be expected. Voltage unballance leads to a reduction in the life of three-phase asynchronous motors running on three-phase current. To minimise the unfavourable effects of voltage unballance, permissible limits of ·uu are specified. According to EN 60034-1, three-phase motors may only be operated in a power supply system where the voltage unballance may not exceed 1 % continuously or 1,5 % for only a few minutes. To comply with these stringent requirements, it is necessary to limit or compensate the unballances [1.5]. In practice, the single-phase power is usually connected in a cvdically ehauged manner with the three-phase net,vork, as can be seen in Figme 1.8 undr.r b). However, this type of feeding leads to a compromise in the single-phase rwtwork with regard Lo optimum operation, which would he the case for thr comwction shown in Figtm! 1.8 a). Phase separations arc necessa.ry which allow fo<~ding, to the~ cont.ad, lines frnm ot1<'. sidr only. At
42
1 Traction power supply systems
Overhead contact line
;JJO
U = Un
I !200A
I AT1
Track I
Negative feeder U = - Un
300A
200A - -
100A ':-,.
,..
I
100AQl4008 j100A 25 kV j TU ,· AT450 kV l200A 200A 1100A 25 kV I 100A I ' · - - 200A - - 100A
AT2
AT3
Figure 1.9: Basic design of the 2 x Un feeding system. Un = 25 kV, feeding from the 220 kV grid, T = substation transformer AT= autotransformer, TU= traction unit, currents at Sn = 10 MVA.
phase separations, the applied voltages have a phase shift of 120°. The voltage difference at the phase separation is v3 · 25 kV :=:::: 43,3 kV. Higher voltage drops result in the overhead line network and create unfavourable conditions for electrically regenerating traction units. Feeding as shown in Figure 1.8 b) is preferred for use by SNCF, who have approximately 8237 km (1999) of traction line electrified with AC 50 Hz single-phase. This type of feeding is also used on the high-speed line Madrid-Seville [1.6]. On this line, the transformers of the individual substations are connected by a 60° connection in such a way that the voltage differences at the phase separations correspond with the nominal voltage of 25 kV [1.7]. , In Russia, where over 21500 km (1999) of track are electrified with single phase. AC 25 kV 50 Hz, transformer connections are used, to partially correct for symmetry (see Figure 1.8 c) and d) ). Phase separations are also necessary, however, they can be installed in the vicinity of the substations. The parallel operation which can be implemented as shown in Figure 1.8 d) yields high compensating currents in certain conditions. To improve transmission properties, the 2x25 kV system is used for high-performance traffic in France, Japan and Russia on single phase AC 25 kV 50 Hz railways. This type of feeding is characterised by additional auto-transformers and a return line at a potential of 25 kV. This return line is often designated as a negative feeder. For this reason, twin-pole switch gear is required in the overhead line network. The basic design of this type of feeding can be seen in Figure 1.9. The line is supplied by a transformer with a centre tap. The centre tap is connected to the rails. The voltages between the negative feeder and the rails and between the overhead contact line and the rails are both 25 kV. The potential difference between the overhead contact line and the negative feeder is up to 50 kV. The transmission of power between the substation and the auto-transformer preceding the section on which the traction unit is collecting electric power fr9m the contact line occurs as in a twin-pole 50 kV line. The low currents involved with this transmission of power result in lower voltage drops in the overhead contact line network. In the section between the substation and auto-transformer, the current flowing in the rails is low due to the a.lmost 180° phase shift in the equally large currents in the overhead contact line and the uegative feeder. The interference with adjacent lines is tlwrefore very low. In tlw S<\ctioll hetw<~cu two a.11(,0-transformers, the traction nnits are foci from both ends, the rails S
/
43
with adjacent lines is therefore also lower than in single-ended feeding without autotransfor111crs. In principle, this type of feeding can be used with an n-fold nominal voltage, e.g. 3x25 kV. In this case, the transmission of power to the auto-transformers, between which the power consuming traction unit is located, would be performed with a voltage of 75 kV. It should be noted that this feeding principle can be used for all single-phase AC systems regardless of their nominal frequencies. Electrification of DB's Prenzlau to Stralsund line carried out by AC 30/15 kV forms an example [1.8]. The requirements on the design of the insulation increase in systems with n · Un. For example, the larger air gaps necessary between parts with multiple nominal voltage differences must be taken into account in the overhead contact line installations. The necessary twin-pole design of switch-gear in the overhead contact line network is a further general disadvantage of feeding systems with multiple nominal voltages.
1.3 1.3.1
16, 7 Hz traction power supply of the German Railway (DB) Energy generation
For the DB, the single-phase 16,7 Hz ener:qy generation is carried out in t,velve hydroelectric and thermal power plants each and in ten central transformer stations. At the end of 2000, 2588 MW of power was installed to supply the central network, of which 57 % was generated in thermal power plants, 14 % in hydroelectric power plants, 24 % in central transformer stations and 5 % in rectifier and converter stations. The largest 16,7 Hz single-phase generator in the joint nuclear power plant at Neckarwestheim which produces 187,5 !VIVA at a power factor cos cp = 0,83 is particularly notable. The pump storage plant in Langenprnzelteu with two 16,7 Hz single-phase generators of 75 M\V each used to cover load peaks in the traction network is also unique. In addition the installed power in the DRCS of the decentralised network section was 608 MW. There, the 16,7 Hz energy is generated with synchronous-synchronous transformers with a nominal power of 10 !VIVA. In the DRCS, the 50 Hz frequency is therefore converted to lG,7 Hz and the number of phases is reduced from three to one in the single-phase AC traction supply.
1.3.2
Energy transmission and contact line supply
Aft,<~r gc1w1aticm, the 16,7 Hz traction pow<'r is trn.nsrnitted through out the central 1wtwork of the DB via Lite\ 110 kV overhead linc\s. At the end of 2000, the 110 kV overltead line wtwork or the DB ("0l1Sisted or a lin<' length of 1°l09 km and supplied 161 stdJstatirnts. At I-Ialtingen and Singcn :3 coupling transfornwrs an) used to connect the 110 kV s, st<~111 to the 1:32 kV t.1 action pow<~r Il<'twork of tlH' SBB (Swiss '.\lat ional Railwn_,·s) . lit SL<)indorf nm! Zirl tltl: 110 kV DB 11<'! work is con1wct<'d directlv to the 110 kV 11<)1\\'0ik o[ tll<' <°)BB (:\11sttiau \'atio11;d IL1ihrn,·s) Tl1c' 11.0 k\ m<'rh<'ad line network
44
I Traction power supply syste!ns
110 kV /16,7 Hz Line 2
CL Line 1
CL Line 2
I I I I
I
Line 1
I
:station~
I I I I
I
I I I I
I
:Stations:
I
:Station
I
C:
Station H
Line 3
Figure 1.10: Schematic diagram of a contact line supply of the DB.
of the DB allows for an optimum import of energy and contributes to a high supply reliability in electric traction transport. Because it is operated as a resonant-earthed system, 12 arc suppression coils of 100 A each compensate for the line capacitancies. A part of the 110 kV overhead line runs beside the main lines of the DB to supply the individual substations, which are designed as node-type substations with double bus bars or as simple block-type substations (see clause 1.3.3). An example of a contact line supply of this kind is shown in Figure 1.10.
1.3.3
Standard 16, 7 Hz substations of the German Railway
1.3.3.1
Function and types of standard substations
According to standard terminology, substations are electrical installations with switchgear, control equipment, me_tering, protection and signalling facilities with the necessary instrument transformers. With these, it is possible to switch circuits on and off as required and to switch off faulty equipment quickly and selectively or to isolate it for maintenance purposes. \tVith the DB, substations, switching posts and coupling posts for single phase AC 15 kV 16,7 Hz are designed in accordance with DB directive 995 [1.9]. DB's standard substations are unmanned in operation z,,nd consist of standardised components with standard interfaces, which can be put together and rated in a modular manner according to functional requirements. The standard is used for substations (SS) with 110 kV equipment and 15 kV equipment, - switching substations with a llO kV equipment only, - switching posts (SP) with a several 15 kV supply branches and - coupling posts (CP) with one 15 kV circuit breaker only. Sub.c,tations with transformers convert the llO kV nominal voltage of the 16,7 Hz traction line networks to the 15 kV nominal voltage of the overhead contact line. They distribute the traction pm\·er to the individ1u1l fc~C'ding brandies.
1.3 lG,7 I-fa tra~:tio1_1_yowcr supply of the German Railway (DB)
45
Suntc/1,1:ng substalior1,s without transformers are used to connect and branch the 110 kV electrical traction lines. Swdching posts connect the overhead contact lines and feeders of several railway lines and supply overhead contact line sections fed from one end with 15 kV power. Co'u,pl'ing posts connect two feeding sections and are used especially in cases of long distances between substations or long sections fed from one end to guarantee the correct functioning of protection. The substation design hand book maintained by the DB, forms the hub for planning and errection of the different typs of substations. The standarized interfaces specified there enable using of and continuous development of functionally equivalent equipment of various manufactures. It consists of numerous design documents and circuit diagrams, on the basis of which all standard substations are planned and constructed. Standard substations of the first generation still contain pneumatically operated circuit breakers, control, signalling and protection technology with mostly mechanical relays. The 15 kV vac'U'Um circuit breakers introduced at the beginning of the eighties, electronic information processing and protection systems fostered the transition to the second generation of standard switching substations described below. These are typified by a significant reduction in equipment size, installation and maintenance efforts [1.10]. 1.3.3.2
110 kV open air equipment
DB's directive 955 includes standard specifications for the design of the 110 kV system, based on operational requirements. The main features are: 110 kV equipment with double bus bars, two longitudinal isolations and a coupling, 110 kV equipment with single bus bars and two longitudinal isolations and 110 kV equipment in block operation for block-type substations. Each substation consists of several branches e.g. traction power lines, transformer and longitudinal isolation branches or block branches, which are chosen according to the local requirements from numerous standard branch types. A typical general C'tTc'uit diagram of a block-type substation is shown in Figure 1.11 and the associated plan view in Figure 1.12. Whereas substations with single or double bus bars in transformer and traction overhead line branches are equipped with circuit breakers, the block substation of the DB has no circuit breakers in the traction overhead line outlets. Substations simplified in this way are used as intermediate substatious between fully equipped node-type substations whose circuit breakers in the overhead power line branches switch off faulty ovcrlwacl power lines including those in the vicinity of blocktype substations. Standanl specifications for the electrical, mechanical and geometrical design apply for circuit breakers and disconttcctors, instrument transform(~rs and earthing coils, and ctcl1icvc 1natching and interchattg<'ablity of equivalent typ(~s of equipment from different 111a11 ufact. urcrs. Iu the substations witlt and without tn-rnsfonners, the i11divid11cd svstc'Itl circuits of th<' iuc01lli11g m (~rh('ad po\\'<'! li1tl'S are cm1necU\d bv the phase cond11ctorc; Ll and L3
1 Tract.~on12_()wer supply systems
E3
E2
E1
-011
1- , 16, 7 H, 110 kV 1· 300/50 ACS_R
-
7
-------1 -
1
-T5
$1
@-015
.t
@-016
@
-oo@
-OO[i]-
[iJ-
f I -T10 I -T1
-T1
-09
@I
f
I
-09@-
-T10
I
-08
Block branch
Longitudinal isolation branch
Block branch
Figure 1.11: llO kV general circuit diagram of a block substation.
and standard conductering ACSR 300/50, single or bundled conductors, via overhead power line branches, with the bus bars, Al/St 300/50 or Al/St 1045/45 (see Figure 1.12). The cables of the overhead power line are anchored to section supports or overhead power line end supports with vertical suspension. They are then connected to the line disconnector (Q9) designed as double-pole rotary disconnector with attached earthers (QS) (Figure 1.11), which are driven by the fused DC 60 V. voltage as are all diconnectors in standard switching substations of the second generation. The twin-pole circuit breakers (Q0) contain SF6 as a quenching gas and an electrically powered spring or pneumatic drive for actuation. Single-pole, oil-filled combination instrument transformers (T5) are used to measure currents and voltages. 15 MVA single-phase oil transformers in mobile design for outdoor installation with ONAN cooling are used as power transformers (Figure 1.12). A peculiarity of these power transformers are special lift limiting devices. They prevent the loosening of the windings due to the approx. 150 short-circuits per year [1.4]. The transformers are insulated against earth and earthed by tank leakage protection tro:nsformers. They are also equipped with current transformers (Tl). The bus bar disconnectors (QI, Q2) are used in substations with double~ bus bars to change between bus bars. The longitudinal bus bar disconrwctors (Qll, Q21, Q12, Q22) are connected to one or two attached earth electrodes (Q15-Q17, Q25-Q27). The bus ha,r disconnectors (Qll) with attached rartbers (Ql5. Q!G) wrnilcl allmv l'rc~cling of
1.3 16,7 Hz traction power supply of the German Railway (DB)
47
\ \
\ \ \ \
Transformer 2 B- -
Figure 1.12: Plan view of a block-type substation.
the transformer from the other respective circuit if the line partially failed. The pole arrangement of the disconnectors depends on the system design successively with pole centre distances of 2800 mm or 3000 mm, adjacently opening in the opposite directions with pole distances of 1400 mm or adjacently opening in the same directions with pole distances of 2000 mm or 3000 mm. Because the 110 kV network of the German Railway is operated in resonant-earthed condition, arc suppression coils with integrated neutral point are installed at selected substations. The arc suppression coils are designed as solid core coils with step switches or, for frequency control, as plunger coils with an inductive current of 10 A to 100 A. For telecommunications via traction overhead power lines, carrier frequency tra11smission devices (PLCT) ·with chokes and coupling capacitors are used in various substations. The mesh earth electrodes used consist of tinned copper conductors with a cross section of 9S rnni'2. They are connected by loops with all steel components and with hall type ca.rthing studs. The lightning protection rods attached to the lighting masts and the earth wires above the traction overhead power line branches and bus bars protect against lightning.
1 Traction power supply systems
48
=1<3
=1<5
=K7
OBB 1-16,7Hz15kV TBB ---l----------...------t-------t~..,-----.,---::-:-:c:----t-----t---, -064
-06 -01 -00
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i
-01
-016
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~
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9 -TS
I
I
I
J' J' J
'' ' ' Transformer branch
-TS
n n I
I
'' ''
''
9
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Overhead contact Longitudinal disconnecting Test branch line branch
=1<8
and metering =K4
=1<6
=K2
OBB -012 1-, 16,?Hz, 15kV TBB -----+--------,-=---+----+--~--06
-062
-01
-Q6
M
-01
F
-01
-00
-017~
-00
F
-F1 -T1
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9
-Ost{
n n I
I
'' :
'' :
n n I
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'' :
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Overhead contact Longitudinal disconnecting Overhead contact line branch and metering line branch
Figure 1.13: 15 kV general circuit diagram of a substation.
1.3.3.3
15 kV indoor equipment
In the medium voltage range, the standard indoor equipment consist mainly of the following configurations: 15 kV installations with one operating and one test bus bar and two longitudinal isolations, 15 kV installations with one operating and one test bus bar or 15 kV installations with one operating bus bar. The first variant shown in Figure 1.13 represents the usual case for substations and switching posts. Due to the parallel connection of the overhead contact lines of a twin-track line, each feeding direction and the station in the vicinity of the substation are usually each supplied by only one overhead contact line branch_ The type of installation depicted in Figure 1.13 therefore contains three overhead contact line branches and the usual two transformer branches of a substation.
1.3 16,7 Hz traction power supply of the German Railway (DB)
Earthin
49
TC
devices
N
I
0
LC)
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<( ()
> 0
co N
!:::
~
[/) -'£.
en
o3
OJ
t: ><
0
OJ 0 .0 0 ()
2
4
6
8
i:
Auxiliaries power room
Medium voltage room 15 kV
3
5
7
Protection
Figure 1.14: Arrangement of the medium voltage and secondary technology in type KS substations or switching posts.
The operating bus bar (0 BB) made of 1 or 2 x 80 x 10 mm copper straps is used to couple the individual branches, to distribute the current and to provide the voltage. The overhead contact line and return voltages tests are carried out using the test bus bar (TBB) made of 50 x 5 mm copper straps as described in clause 1.3.3.6. Due to double-row arrangement of the equipment, both bus bars are arranged in a U-shape and can be separated for maintenance and repairs by the longitudinal disconnectors Qll, Q12 and Q61, Q62 into several sections with corresponding measuring devices. Transformer and feeder line branches are arranged at the ends of the operating bus bar. A third transformer or an additional mobile substation can feed into the centre section if necessary. By the arrangement of the overhead contact line branches, which serve as back-up supply, to different OBB sections, e.g. to a branch supplying the railway station in the central bus bar section a high degree of availability of the substations is achieved, e.g. during maintenance works at one of the bus bar sections. The circuit design of the test bus bar is explained in clause 1.3.3.6 in relation to the automatic testing of the overhead contact lines. The 15 kV branches are arranged according to Figure 1.14 in a double-row steel rack with a centre passage, which is protected by solid steel doors and an anti-arcing ceiling. To detect short-circuits in the 15 kV system, the main frame and the steel rack are insulated from the building and earthed through a rack current transforrner with a transformation ratio of 1000/1. The designation of the type, e.g. K8, refers to the number of cubicles and the number of overhead contact line branches (see clause 1.3.3.7). The vacumn circuit breakers ( QO) consisting of the switch gear trnck and one or two vacuum tubes are chosen acc-ording to the locally expected short-circuit current between 20 kA and 50 kA and for a nominal current of 1600 A or 2000 A. They arc connected by copper expansion strips to the bus bars. The response time of thr circuit breaker is around 17 ms [1.12]. The spring drive is operated with the DC GO V fail safe supply.
'I"-"::-;..,..,..,...,.,._ _ _ _ ._._
( 1 Traction power supply_ systems 1 - - - - - --, 1 Stand-by I
: generat- :
0'2Q. SE:! __ :
Isolating transfor'-m_e_r~~
Public power input
;--====]____
iPanel2 DC60V
Panel 1 AC 230/400 V 50 Hz
, :
rj___ Rectifie Rectifie
2
Countercell unit
Battery hall
Battery hall
1
2
1 1 I
- Protection -SCADA - Equipment drives
1 1
-----r------~
I I
L _____
1 I I
I I I I
I ....1
r ______
- Lighting - Power sockets - Heating
7
:_7
1 Inverter I
L-
Panel 3 AC 230V / 50 Hz
j _______ 7
1-PLCT :-EMS
:
I
I
I
L--------------J
Figure 1.15: Schematic diagram of the auxiliaries' supply of DB's substation and switching posts. - contained in every installation - - installed only if required
Sliding-type dis connectors are used as the longitudinal dis connectors (Qll, Q 12, Q61. Q62) and switch-disconnectors as test disconnectors (Q6). The OBB disconnectors (Ql) are suitable for a nominal current of 1600 A. The earthing disconnectors (Q8) are suitable for closing on to a short circuit. Resin encapsulated current transformers (Tl) with a nominal voltage of 24 kV are used in transformer, overhead contact line and feeder line branches. They transform the corresponding currents for protection and meatering. To measure the framework current, the total current of the transformer and the earth current of the mesh earth electrode, low-voltage transformers with pressed resin insulation are usecL These are located in the neutral bar cubicle of the substation (Figures 1.19 and 1.20). Thereby, certain disturbed conditions, as a short circuit between bus bar and structures, can be detected more rapidly. 50 VA voltage transformers (T5) are used in coupling posts and in switching posts with single bus bars for the overhead contact line branches and for measuring, longitudinal isolation and test branches. With their output signals the overhead contact line and bus bar voltages can be monitored. High-voltage fuses (fl) are installed upstream of the voltage transformers. To limit the current during overhead contact line testing, a high-voltage resistor Rl is installed in the test bra.nch, which is protected by high-voltage fuses (Fl, F2) with tripping signals. 1.3.3.4
Auxiliaries' supply
The principle of tlw a:11,:rilia:rzes power supply (Figure 1.15) for substations and s,,·itching posts of the DB, is the scpara,tion of the supplied equipment into two or three groups according to their importance in maintaining the functional capabilities or the switching equipment and thereby electric: traction operation. The first group consists of eq11ipment ·which can be foregone for brirf periods, e.g. if the local maius fail and is supplied from an isolating transfonu<'r all(! AC distribution 230/400 V :j() I-L, (pand 1). This includes lighting, tlw pow<'r sock<'ts (poit1ts) and lwating. Tll<' s<~rnnd grrn1p iwl11des
1.3 16,7 Hz traction power supply of the German Railway (DB)
51
continuously required equipment such as protection, SCA.DA and the equipment drives are supplied through rectifiers, a buffering battery and the counter cell unit by the DC distribution DC 60 V. Since 1996 rectifier control and battery monitoring has been performed by a control cubicle. If it is necessary to supply continuously operating equipment such as transmission device carrier frequency modulators PLCT or disconnect.ors and electric signals of emergency neutral sect.ion (ENS) with a nominal voltage of 230 \·. This is then conducted by an additional AC 230 V /50 Hz distribution panel (panel 3). The fail-safe voltage for panel 3 is provided by DC/ AC inverters that are supplied with DC 60 V from the fail-safe voltage of panel 2. A special case is the auxiliaries supply at coupling posts, where. the 15 kV voltage of the overhead contact line is transformed to the required voltage by auxiliaries transformers and the battery is charged by separate recitifiers. The isolating transformers rated from 10 to 40 k VA depending on the substation size and the circuit group DYN take care of the protections and interference-related isolation from the local AC 50 Hz network. The rectifiers, of which the second is only connected when the first fails, supply the two separately fused 60 \. battery halves designed for a five-hour emergency power supply. Panel 1 has a connection for an additional stand-by generation unit, which should be available in due time if the local network failed for more than five hours.
1.3.3.5
Protection
As the only type of protection, coupling posts receive overhead contact line protection. In switching posts, the general protection is supplemented. Block substations have additional transformer protection. All other substations are equipped as shown in Figure 1.16 with general protection, overhead contact line, transformer and traction power line protection. In substations without transformers, only the overhead power line protection is used. The general protection is equipped with three protective functions: The bus bar protection for switching posts and substations 1 which is triggered immediately on short-circuit current in the frame work of the 15 kV installation and the frame work current transformer with of more than approx. 0,5 kA, switches off all 15 kV circuit breakers by the main or reserve actuator and, in substations, also the 110 kV circuit breakers. Cfrc'IJ,zt br-eaker monitor·ing, which is triggered by the ··Off" command for the circuit breakers of the overhead contact line or overhead traction power line prnf;e.ctzon and leads to switching off the circuit breakPrs initially triggered but not tripped within a pre-set time. Total c11·1Tent rnon:itorin_q, which switches off all lS k\. circuit breakers when the c111T<~ILt measured by the total current trausfornwr (~xcceds an ad_justable value dming a specified period. Th<' g()tWral protectioIL device thereby provides important backup protection. For 0·1 11:rluwl zu1w1T line vrntcdi.cm, a static proL<'ctio11 l!llit is installed in the second
1 Traction power supply systems
11 O kV overhead power network
_____, Overhead power line protection
General protection
Transformer protection
---,--i Overhead contact line protection
Overhead contact line feeder point
Figure 1.16: Schematic diagram of the protection design of a DB substation. - coupling through SCADA
generation standard for 16,7 Hz substations and, in the installations constructed since 1993, a digital protection unit is used. This protection unit is equipped with several time and direction distance steps, polygonal triggering zones, directional detection with high sensitivity, rapid activation for switching short-circuited lines, fault localisation, earth contact relays and automatic re-closing. The exchange of information with the power system control is possible through a serial optical glass fibre interface. To detect network faults, the impedance of the circuit is measured. If a network fault impedance was recorded an angular measurement would be made to determine the direction of energy flow during the short-circuit. Depending on the fault impedance and the measured angle and if the low impedance exists in both conductor-earth loops, the activation command is issued to the circuit breakers through a series of timer elements. A.n analogue transient earth fault relay, used to measure earth short-circuits issues a transient earth-fault signal with the direction and the permanent earth short-circuit at the binary outputs of the protection relays. In case of a single phase earth fault, the overhead power line and therefore, the supplied substations can continue to operate over a limited period of time (approx. 2 hours). Transformer protection, a static protection unit, is installed in standard second generation substations and, since 1995, digital protection units have also been installed. The static protection unit is equipped with high curren~. time protection for the highvoltage and low-voltage sides, tank protection which measures the fault current in the tank protection transformer and an activation signal multiplexer for the Buchholz protector and the stepping switch of the main tra.nsformeL Because block-type substations ax<\ not equipped with overhead power li1w protection, additional imp
1.3 16,7 Hz tractio11 power supply of the German Railway (DB)
53
is used in their transformer protection relays. The digital transformer protection unit also incorporates differential protection, and thermal overload protection and the above mentioned facilities for storing activation data. A detailed description of the overhead contact line protection is contained in clause 11.3. In node-type substations, central protection data units are used to store and transfer the data of all digital protection relays.
1.3.3.6
Supervisory control and dat{l aquisition system (SCADA)
The supervisory control and data aquisition system (SCADA) is a central system for the control, automation, information processing and transfer, which conforms with the traction-specific requirements of the standard AC 15 kV 16,7 Hz switching equipment. It was used in the middle of the 1970s as a recording and registering system and has been developed since then to a multifunctional substation control centre with data display technology. Its connection to a rail network, i.e. to the 15 kV or 110 kV installations, the auxiliaries power distribution and to the protection system is made by specially laid cables with a flexible, tinned screen, earthed at both ends with respect to electromagnetic compatibility (EMC). All switching equipment and current transformers are directly connected and no additional panels or electrical cubicles are used in the 15 kV or 110 kV installations. The SCADA consists of the following functional parts: Local control, Automation components, Signal and measured value processing, Digital meter monitoring and processing (DMM), Remote control system, Interlocking and Implementation. Local control was used until 1993 in the form of push buttons on the front panel of the control cubicles. The unit required two-handed operation and was equipped with LED service signals. The data display technology used subsequently, employs a TFT monitor with full graphics in window technology. The switching equipment and the desired switching states are selected in a one-handed operation. The necessary two-handed control for the subsequent command output is ensured by an additional keyboard. The equipment is displayed in defined colours blinking when changes in the state have been selected. Numerous additional functions such as securing, locking, storing, acknowledging, adoption of responsibility, the fault reporting list, the operational reporting journal, general inquires, parameter adjustment facilities allow the dialogue between the operator and the SCADA. The follmving autornatwn components secure the automatic operation of the 11nm,urned substations and reduce the work of the operating personnel: Automatic overhead coittact line testing (ACLT), - Auto111at.ic overhead contact !in<' r<·\·crS
54
1 Traction power supply systems
Automatic overhead contact line re-closing (ACLR), Automating of emergency neutral sections (AENS) and 15 kV and 110 kV automatic synchronising device (ASD). The automatic overhead contact line testing (ACLT) verifies that the overhead contact line branches are free from short-circuits before the circuit breaker is switched on and after every activation of an overhead contact line protection unit. Therefore the test branch is connected temporarily via the test bus bar and the test disconnector Q6 with the overhead contact line (see Figure 1.11). The test criterion is the voltage at the voltage transformer T5 of the test branch. If this is above 7 to 8 kV, the test result is considered good and the circuit breaker QO is re-closed automatically without delay except in cases of activation of the reserve protection unit and in cases of activation of the thermal protection, with an delay until the overhead contact line has cooled down. A unsatisfactory test result, that means a testing voltage belmv an adjustable threshold of 7 to 8 kV, excludes reclosing of the circuit breaker and is signalled to the master control centre (CC). This automatic procedure excludes repeated short circuit stresses and prevents wearing of the equipment. The entire test procedure for an overhead contact line branch takes less than 10 seconds from the activation of the protection to the re-closing of the circuit breaker and does not affect the railway operation. If several overhead contact line branches are cut off simultaneously, the test is made in an adjustable sequence to allow the voltage to be returned quickly to the most important supply sections. A 1domatic overhead contact line reverse polarity testing ( ACLRT) checks the reverse voltage of an overhead contact line branch when a command is issued to close the earthing disconnect.or Q8. The expression "reverse voltage" means a voltage which might be in the overhead contact line after tripping of the circuit breaker. For this, a self-test of the measuring circuit is performed, after which the bus bar disconnect.ors Ql in the test and overhead contact line branch is opened and the voltage transformer T5 is connected via the test bus bar and the test disconnect.or Q6 to the overhead contact line branch. If the measured voltage falls below the value previously set, taking account of the induction voltages caused by adjacent overhead or feeder lines, the test is regarded as satisfactory and the earthing disconnect.or Q8 is closed automatically. By the automatic procedure reclosing of short circuit currents by the earthing disconnector Q8 is avoided. The automatic overhead contact line re-closing ( ACLR) used in standard substations without test branches automatically re-closes the circuit breaker QO after a protection unit has responded. The operating voltage has then been returned in an pre-set time after a successful test of the overhead contact line by an adjacent substation. The automating of emergency neutral section (AENS) controls the disconnect.ors and electric signals of the neutral section located in the de-central network of the DB. They are dependent, on the switching state of the feeding circuit break<'rs and disconnect.ors. The criterion for the re-closing of the overhead contact line voll.age to the emergency neutra.l section ( ENS) is the completed coupling of tlie adjaccmt dc·-c·<:nt.ralisecl converter stations vi,1 ill(' ln1s liars.
1.3 16,7 Hz traction power supply of the German Railway (DB)
55
The autornatic synchronising device (ASD) verifies the synchronising conditions before enabling the on command for the circuit breakers. These include the phase synchronization and equal amplitude, taking account of permissible voltage differences caused by different line loads and possible by-pass conditions if voltage is lost at one side. The signal and measured value processing includes the acquisition and preparation of all standardised operating signals (OS), such as circuit breaker position and disturbance signals, the branch currents, bus bar and test voltages, reactive and effective power, which are necessary for the operation and fault analysis of an unmanned substation. The acquisition of measured values is performed by measuring transformers. Measured value processing includes extensive adjustment facilities for cyclic and dialed measured values, limits, thresholds and windows to compensate measured value fluctuations. It also includes an algorithm to determine the interfering currents of overhead contact line branches and digital metering monitoring. In the western part of the German Railway, all substations, converter stations and power plants have been equipped with a separate digital metering value transfer. In addition to the metering impulses, they transfer the position signals of the 110 kV bus bar disconnectors and circuit breakers provided by the information processing system as so-called channel signals, through a separate remote control connection to the power network control centre at Frankfurt/M. Because the general technology is no longer capable of extension, installations constructed since 1994 have been equipped with digital metering, value monitoring and pre-processing integrated into the information processing system. This monitors and processes the impulses coming from the effective and reactive power meters according to an algorithm which can be adjusted according to time and values and transfers meter values for the remote control module of the information processing system at transfer intervals of several minutes. The intelligent remote control system, also integrated in the information processing system, will be described in conjunction with the power system control under clause 1.3.4.3. The interlocking is computer based and software controlled. The circuit breaker and disconnector positions have multi-signal monitoring and in this case use double signals for the associated fault position monitoring. To avoid interlocking errors, the number of simultaneously controllable types of switching equipment are restricted to one per branch. Disconnect.ors and switches for 110 kV with attached earth electrodes are also interlocked with each other by hardware. Older SCADAs are equipped with relay implernentahon of signals and commands from loca.l and remote controls. The automation components at the GO V voltage level, the signal inputs and two-pole command outputs, arc located directly 011 the computer circuit boards since the introduction of data display c-outrnl and a,n) c,:-1rried out by associated relays or optical couplers with the necessary insulation resistance. To increase the availability, redundant, nmltiple computer systC'ms arc used in the iuformation processing, system. They are equipped with the associated local control, nm1ote control and servic<' int
~---
56
1.3.3.7
1 Traction power supply systems
Buildings and supporting structures
The standardised buildings (Figure 1.14) used to house the 15 kV substation equipment and the secondary components are constructed of prefabricated parts with integrated thermal insulation, i.e. in sandwich design, on strip foundations and a concrete slab. The reinforcement of all concrete parts including the prefabricated roof, is connected via earthing rods to the foundation earth electrode forming a Faraday cage. The shortcircuit current conducting capability of these earth conductors is 40 kA for one second. The foundation earth in switching posts is connected through the main potential compensation bar and earthing cables and in substations through the neutral bar cubicle and return conductor cable to the main tracks. Switching posts and substations use building types K 4 to K 16 with 2 rooms (Figure 1.14) and types GW 10 to GW 20 with enlarged auxiliaries rooms and an additional workshop. Usually, the GW type is used only for node-type substations. The digit following the K or GW provides information on the number of the 1,40 m wide 15 kV cubicles, which being arranged in two rows determines the length of the 15 kV room [1.11]. The individual rooms are separated by fire walls and fire prevention doors. The 15 kV room is designed for a positive pressure of 0,16 bar and is equipped with ventilation flaps for air pressure compensation and temperature-dependent ventilation for the test resistor of the overhead contact line testing device. Instead of a cable cellar, tubular openings are used for the entry of the cables. A sandwich floor is used for laying cables within the building. The room for the secondary equipment, known as the auxiliaries room, is equipped with forced ventilation powered by the battery. A further ventilator is installed in the workshop. Switching stations for 110 kV without transformers do not have a 15 kV part. For coupling posts (CP), a re-locatable, monolithic post is used due to the small space requirement. The earthing and ventilation of the buildings are carried out as for switching posts (SP). The minimum permissible room temperature in unmanned units is 5°C in the auxiliary power room and -5°C in the medium-voltage room. For 110 kV outdoor switching equipment in substations hot dip galvanised dead-end equipment supports is used and installed in sheaths of standardised round or block foundations made of cast in-situ concrete or of prefabricated parts depending on the subsoil conditions. Standard arrangements for 110 kV branches and required clearances are specified by DIN VDE 0101 and EN 50 110. The transformer foundations in the substations, which must bear a mass of over 50 tons, are equipped with an oil drip tray, the level of which is constantly monitored. They are located at a loading rail or at a substation road suitable for heavy transport . The earthing of all structural steel components and the ball earthing components is carried out by the mesh electrode connected in substations to the neutral bar cubicle.
1.3 16,7 Hz traction pow~~- supply of!~~~Qe~man Railway (DB)______
1.3.4
Power system control
1.3.4.1
Development, functions and design
__________57 _:_
The power system control of the German Railway encompasses the total of all technical equipment used for the operation of the traction power and overhead contact line networks, the snb.stations, converter stations and power plants. Its design and principle functions closely related with traction power feeding by overhead contact lines. In the past, the task of the control sy:;tem was almost exclusively the control of 15 kV overhead contact line dis connectors and 15 kV and 110 kV dis connectors and cirrnit breakers in substations. These were controlled by manned local operating facilities, such as interlockings and control centers, using relay based control, control discrepancy switches, mosaic panels etc. The increasing requirements for safe and economic operation and the introduction of unmanned substations extended the tasks of the control system significantly. Due to the greater distances between the control system and the switching equipment, the tenn remote control technology was coined. This increasingly achieved a central cha.racter and today encompasses the entire network of the German Railway. Remote control also includes telephony, because communication remains necessary between the maintenance personnel or switching requesters and the switchmasters often hundreds of kilometres apart. The operating facilties are therefore equipped with railway-owned telephones and intercom connections. In particularly important installations such as substations and switching posts they are connected with the control centres through permanent lines or dialing connections. The operation of unmanned installations also requires more extensive information on the state of the switch gear, protection and auxiliary equipment. This is partirnlarly so in the case of a fault where purposeful plain language recording allows the supervisory personnel to analyse the situation and initiate the correct actions to localise the fault, substitute the feed and eliminate the fault without long interruptions to railway operations. The necessary installations for this process of internal system signc1 ls, also increases the volume of information on the high level network power system. rnntrnl. Additionally, recording and transmitting of measured data are necessary. To cn·oid excessive transfer and processing work, more and more information is pre-1noccssed at the lower level and the procedures are automated. With automatically running subroutines, using macros with command scqucnr,·s, e.g. to swi:,ch off particular sections of lines, switchmasters can be relieved of \\"01 k. Rernote diagnosis takes on a special significance, enabling fast fault analysis In ltiglily specialised, centrally located personnel. The quantity of information and the rapid control of the rnnning prnccss('S rcqllire suitable transfer media to ensure data transfer at high speed. The 'i.n.te_1rm.lcd 11d:wmk (IN) and CIR-NET (Computer int('grated railroading net) of tlw 1Jernwn Haihrn,v are increasingly adopting optical fibre tcd111ology to achieve transfer rates of lip to (i-l k8d. Tlw control structun\ of the power syste111 is depicted in Figure L 17 Th<' 111.(1,ster conlnJl centres (!VICC) S<'l\'(' for controlling and signalling of the I G k \ ('([ltipttwnt. In l·rn,nsm:1,:;sum cont.ml u:nlres (TC'C) and ndwor/,: wm:,r1.an.d 1:1:nlr<' ( NCC) o!ll_y the
1 Traction power supply systems
58
IN
GWS RCM LCU station
LCU
~ SCADA
RCM/LCU
RCM station
~ SCADA
Figure 1.17: Schematic diagram of DB's power system control (abbreviations, see text and Appendix 2).
110 kV control and signalling transfer is processed. The basic principle and functions of the most important components are explained below.
1.3.4.2
Local control units and remote control lines
In order to fulfil the high availability requirements of overhead contact line installations even in the case of disturbances or maintenance work, they are subdivided into numerous main and auxiliary circuit groups. The individual overhead contact line sections are supplied by electrically-driven disconnectors and are monitored by short-circuit signal transformers arranged in series to parallel disconnectors addressed as type five disconnector in DB's installations. They connect the main groups in railway stations. Local control units (LCU) are used to control and monitor the disconnectors; they are installed in the interlocking building of every railway station. The disconnectors are connected by linkages to the drive motor, which has two windings but no separate contacts for feedback signals. Therefore, special hardware modules arranged in the LCM are used to processing the twin-pole command output and feedback signals transmitted on the three available strands supplying the disconnector drive. The hardware modules convert the 60 V control commands of the remote control nwclule (RCM) into the 230 V level of the drive motors and create isolated feedback signals depending on the flow of current in the drive. They are equipped with monitored automatic circuit breakers to secure the circuits and isolate the electronics from the voltages induced in the conn0.cti11g cables. Special measuring modules are available to measure, display and acknowledge the transient impulses of short-circuits. In older installations, in evrrv interlocking building, local control panels are available for opera.t ion or the LCU I>, t lw tralfic controllrr if the n~motc control link fails. This
1.3 16,7 Hz trac:t,ionpowcr supply of the GennaH Railway (DB)
59
--------------=::.-
control function was also centralised in the course of the introduction of central interlocking and fitted with modern data display technology. Tlw remaining remote control modules in the lllllll,t11ned installations are connected for this purpose by a remote control sub-centre function. The RCM converts the signals into frequency-modulated, digital telegrams that are transferred to the general control systern, usually in half-duplex by AC telegraphy (ACT) in regular operation with regular inquiry cycles, known as polling. Up to 30 substations call be included in one remote control line, that communicates within one transmission and reception module in the master control centre. The RCM of larger railway stations are operated in end-to-end mode because of their significance. Modern installations are connected by the gateway substation ( GWS) necessary for IN communications and the CIR-NET. Transmissions are carried out as necessary, i.e. in spontaneous operation, with regular verification telegrams. The RCM adds also the real time and fault position to the telegram.
1.3.4.3
Remote control technology of the SCADA
The remote control ·modules of the supervisory control and data aqui.sition (SCADA) are permanently integrated components of these systems. The design and interaction of the SCADA with the individual components of the standardised substation and the overhead contact line are described in clause 1.3.3.6. The mechanical loading line exerted by the pantograph on the overhead contact, its proximity to railway traffic, heavy electric load fluctuations by starting trains etc. makes unplanned events considerably more frequent in comparison with the transmission lines of public utilities. The resulting protection activation can cause interrnptions to railway operation. Consequently, special requirements must be put on the rernote control system as part of SCADA to a.void a confusing rush of signals and to allow rapid, efficient evaluation of the information. The fault analysis is significantly simplified by linking all information of an event in a telegram with flexible length and its presentation in just one line in the record. This information comprises the protection activation criteria. the switch failure signals, the real time which could become a determining critr.rion, the cirrnit breaker S\\'itching period. A DCF 77 radio clock is used for tirne synch:ronisatum. The transmission of information is carried out with priorities. Protectiou activation signals have precedence, e.g. before measured values. Th<' extensive addit,ional information provided by digital protection equipment can he transmitted by seri;-1I transmission to tlw substation information processing ccntr<' at times of lower data transfer volumes. Us<:less information such as spmious signals ca11scd h_v relay contact. bounce is suppressed aud replaced by a fault signal. In adclitiun. tl1<1 rn111p11U•r syst.e1t1 rucmitors every signal point. for repeated signals. An echo filter is (~rnploycd The cot11wc-! io11 of tlw substation information prnccssing Lo t.he 111.askr c:011./10! centres is usuall\· mad(' i11 end-to-cud 111od(' Ii,· the polling syst<'lll alld Lil(' d11pl
60
1 Traction power supply systems
grated converter and a GWU to the integrated network or CIR-NET.
1.3.4.4
Converters, remote control nodes and satellite control centres
With the increasing degree of centralisation of the power system control, it was necessary to adapt the previously used various telegram structures of the remote control modules into a uniform operating data protocol. As a link between the LCU or SCADA and the MCC process computing system (PCS), remote control nodes (RCN) carried out this pre-processing function in the MCC. At the five transmission and reception modules of each RCN, remote control lines and up to two substation information processors are connected by the principle of area availability via AC telegraphy (ACT) or gateway centres (GWC). After protocol conversion through several communications interfaces, the RCN supplies the process computing system and the transmission control centre (TCC) with information. Apart from translating 15 telegram structures, the remote control nodes compensate the various qualiities of the subsidiary remote control units. They append the reception time of the signals, discern between old and new operational signals (OS), avoid data overflows by buffering, hold a constant image of the process and ensure efficient data input at all levels of computing. With the introduction of integrated networks, it was necessary to partly extend these functions to the remote control units or SCADA levels to allow a uniform IN-compatible protocol to be sent to the GWU. The converters serve this purpose in the same way as the remote control nodes where several remote control links are connected, usually by AC telegraphy. This creates data concentrators close to the process, from which the information is transferred at high IN speed to the general power system control. Satellite control centres (SCC) have a control position with restricted functions and are used as an intermediate solution until the master control centres take over the control of the substations and contact line disconnectors. The remote control sub-centre function of the SCA DA also makes it possible to connect further subsidiary remote control modules. An increased networking of the installations and a flexible application of the functions can be expected with ongoing technical developments.
1.3.4.5
Master control centres
Master control centres (MCC) control the entire 15 kV network and take care of the protection controlling and auxiliaries services. The original MCC with mosaic panel technology and control discrepancy switches were installed in parent substations, to control the child substations and disconnectors. The first computer-aided MCC entered regular operations in 1984 in Karlsruhe, in which a mosaic panel is installed as a fall back [1.13]. A complete change to computer technology has been made since 1987 in Borken, Lrhrt(~, Nurnberg, Munich, Cologne and Karlsruhe. In 1993, the first lVICC based exclusin~ly on computer technology with full functions was opened in iVIunich. In its final eonfiguration, the electrified rail ndwork will h<: divided into the following 11<:w MCC areas apart from '.\ 1I unich: Berlin. Bork<'tt. Leipzig, Diisseldorf, Karlsruhe,
1.4 AC 25 kV 5~l ~I~ tractio!1_J>_crwe1 supply
of tt1~\_Madrid-Seville line
- - - - - - - - - - - - - - - - -61 -
Cologne, Lehrte and NiirnlJerg. A MCC contains remote control nodes, the process computer system, three contrnl desks with G screens each and a service desk for the data and input simulation. In comparison to the control techniques described above, the complete MCC solution has many additional functions which support economic operation with a very large quantity of switch gear. This includes an appropriate visualisation, automatic image displays, measured value statistics, switching programs, sirnulation, automatic short-circuit localisation, data archiving and recordings for short-circuits, interferring overhead contact line currents and control actions. The MCC also contains the remote control substation for the exchange of 110 kV-related information with the general control level. If this connection failed, the MCC would also serve as the fallback level.
1.3.4.6
Transmission control and network command centres
For the operation of the network at the 110 kV voltage level, the electrified network of the German Railway was divided into the four transmission control centres (TCC) Lehrte, Munich, Cologne and Dresden. The transfer of information is made through the 110 kV substation as a part of the MCC information volume or directly through transformers on the low system control level. The network command centre (NCC) at Frankfurt occupies the highest place in the hierarchy of the power system control of the German Railway. It controls the 'U,Se of power from railway owned and external producers of 16,7 Hz energy by optimised energy import, the distribution of energy through substations and the e:r;change of energy with the interconnected grid partners, Austrian Railway and Swiss Federal Railway. For this, the meter values and circuit breaker position signals of the power plants are transferred every minute and those of the substations every five minutes to Frnnkfurt/M [1.13]. After reconstruction, the NCC will perform the tasks of the TCC as \\·ell. The latter will then serve only as data concentrators and back-up level.
1.4 1.4.1
AC 25 kV 50 Hz traction power supply of the Madrid-Seville line Line supply and connection
The Madrid--Seville line, ,vhid1 c0111menced operations in 1992, is 470 km long. It begins and ends in the railway stations of Madrid-Atocha and Seville-St. .Justa with DC 3 kV sections of 8,5 km and 12,5 km respectively. The remaining 450 km of line lwt,Yeeu the two systc-~m separating sections (s('c clause 8.2) were electrified with sing!<~ phase AC 25 kV 50 Hz and can be tn-wclbl at 300 km/h. The required traction power for two traction units of 8,8 lVI\tV each p('r feeding section results in substation intervals or nol more than 50 km if booster lines arc not cr11ployed and a substation power of t>OO I\l\ A [or th<' total line. This includ<~s tit<' power requirerncnt of tlw auxilian· loads s11d1 as railway stations, point lieat.itlg a11d technical
62
1 Tractimi_powe~ supply systems
a)
c)
11'\
L'IL/ 2-1
~ ie
ie
L'IL/ 2 _1= 25 x-/3
43,3 kV
Variant 2: 120° connection, all pointer basis are earthed
Variant 1. 120° connection, all pointer peaks are earthed
d)
SS1 L1 L2 L3
ie
L'IL/2 ,_ 1,= 25 x-/3 = 43,3 kV L'IL/ 2 _1,= 25 kV
SS3'
SS2
§ ci
SS1'
H
SS2'
SS3
§ ci
[j
pHq p
Variant 3: 60° connection, pointer peaks and basis are alternatively earthed
H
CJH[7
[j /
/'.
//
p
contact line track
Figure 1. 18: Connection of the substations by 60° offset.
buildings of the signal service. The traction power supply of the line is prudded by twelve AC 25 kV 50 Hz substations which are fed by the preceding AC 220 kV and 132 kV three-phase installations from the Spanish public grid. The primary connection of the AC 25 kV 50 Hz substations to the three-phase network was made to take advantage of the highest possible symmetry of the load on the AC circuits. As shown in Figure 1.18 a, for substations with cyclic connection, three voltages, result at the secondary side of the substations 881, S82 and S83, which are electrically offset by 120° respectively. If the pointer bases are earthed instead of the pointer peaks, Figure 1.18 b results for SSl ', S82' and S83'. If SSl and S82 were adjacent substations, a voltage difference of ;\[}2 _ 1 25 · v'3 kV~ 43,3 kV would be applied to the phase separation section. Because this voltage can reach the substations through damaged switches or on an unintentional phase short-circuit, the medium-voltage installations in other AC 25 kV /,50 Hz lines had to be rated for the increased insulation value. Due to the limited procurement facilities for switching equipment, they were usually designed as open air switching equi 1)ment for 72.5 kV. For the Madrid-Seville line, the two 120° switching variants \Yere combined. This resulted in 60° switching and the connection of the substations as shown in Figure 1.18 c and cl. This enables design of the 25 kV part of the substation according to the 36 kV voltage level. In contrast, with 120° connection, rating to the 52 kV voltage series would h1:we been necessary because the voltage existing at the phase separation sections during a phase short-circuit of around 43,3 kV would be applied in the substations. The necessary phase separation sections are located between the substations. The chosen technical solutions for the line supply and connection allow equipping, of the substations with n1ore <'CO!lntnical and standardised components_
\ \
J.4
AC 25 kV ~O I:0trc~ction powers1~'l~)f_Jl"-y_o_f_t_h_e_M_,_1c_lr_ic_l-_S_e_v_il_l_e_,_lir_1c_~_ _ _ _ _ _ _ _ _ ___c::6::::3
=
220 kV 50 Hz 0-
l)
I
1 0-
D 2
~J
I
6
0-
er-+ 6
6
0-
=03
I
longitudinal isolation
0-
0-1
feeding 1
1I I I
f
_j
reeding 2 . I . II
. I . I . I . I
. I
'--r-'1 I ---1 I I
0-
I I I
J 7
0-
J3
=J1:
J2
=J4
-=---,J,rr-=-~-====,-=,,:-==-=~~=;=~----""=---~====088 2_!?_1'"'Z ;iQRt .•
CJ
l\~r,
==""llr---'-+---,6--~----+-1---1-~---+-~6~--~---1--TBB
~J h
~
J
= ~
J 6
0-
overhead contact line branch transformer 1 longitudinal separation 1 metering 1
overhead contact line branch transformer
transformer 2 longitudinal separation 2 metering 2
Figure 1.19: General circuit diagram for the substations of the Madrid-Seville line.
1.4.2
Substations and their components
All substations of the Maclricl--Seville line have a uniform design. Their general circuit diagram as shown in Figure 1.19 has a great similarity with the block-type substations of the DB (Figures 1.11, 1.12). As additional components, bus bar disconnect.ors are installed at the high voltage side and auxiliary transformers for the auxiliary supply of the substations at the medium-voltage end. The open-air switching equiprnent (Figure 1.20) for the high voltage section has differing pole clearauces due to the different voltages of 220 kV and 132 kV. The main transformers have a nominal power rating of 20 MVA each and are designed for a load of 150 % for 15 minutes and 200 % for six minutes following operation at nominal power. The high-uoltaqc ci1-c1iit breakers are operated with prnve11 SFG technology. The 'lndom swilch _IJl'./l,T for the medium-voltage section includes a11 operati11g bus bar (OBB) and a (<\st bus bar (TBB) (Figure 1.19). The vu,r:'1tu·rn, circu1,t bn-:akcrs are intended for 1tomitmi rnrrcnts of lG00 A and a cut-off capacity of 2G kA. The test resistor allows test c11rr<'11ts of S A. The auxiliary trn11sfonrn'ts hav<' a uorniual power rating of 100 kVl\ c\ltd sitrnt!Latt<'ously supply the twigltho11rittg Ll1r<'e-phase switch gear ,vith
64
1 Traction power supply systems
feeding 1
=D1
longitudinal isolation =02
feeding 2
=D3
lightning protection rod input isolator
voltage transformer
bus bar
0 0 0
a:; -sj"
transport route
current transformer main transformer
overhead contact overhead contact line termination line termination f-o---------------=5=50'""'0-c-0--------------t
g
§
Figure 1.20: Plan view for the substations of the Madrid-Seville line.
auxiliary power. The protection design includes the overhead contact line, the transformer and the general protection in the same way as at the block-type substations of the DB. As selectivity problems are unexpected because of the single-ended feeding, it is possible to waive distance protection as a part of the overhead contact line protection. The control design is based on substation control and protection system, technology of the DB without data displays. Automatic overhead contact line testing and automatic return voltage testing are included as automation components.
1.5 1.5.1
DC 750 V traction power supply of the Ankaray underground railway system. Line supply and switching
The underground raihvay Ankaray in Ankara/Turkey encompasses a 9 km long line and 11 traction st.at ions. The vehicles travel at 120 sec (headway) intervals and are suppli
1.5 DC 750. V. tr ~t~!;i~>11 p(>\\l~~.~-~~pply of the Ankaray underground railway system.
65
AC 15~ kV
Figure 1.21: Line supply and traction station supply for the Ankaray underground traction system.
installed traction power lies around 1,2 MW per one km of line. The power supply system is explained below. The urban energy supply provides electrical energy for the line at two feeding stations at both ends of the line from the 154 kV network (see Figure 1.21). The transformers 154/34 kV in the transfer stations feed the 34 kV medium-voltage to supply the rectifier substations. With two transformers 34/10 kV, a 10 kV medium-voltage ring is connected to supply the railway stations. The four 2,5 lVIW rect~fier substations each provide the 750 V direct current for the main line. The maximum substation interval is around 2,8 km. For servicing or repairs, the substations can be isolated from both the DC 750 V third rail and from the AC 34 kV medium-voltage system. The open-air depot at the encl of the line is fed from a separate rectifier substation and is isolated from the main line at the tunnel entrance by insulation in the rails and gaps in the conductor rails. Consequently, it is possible to connect the rails to the protection earth of the depot earthing system in the vicinity of the depot and workshop. Th<\ rails of the main line are insulated from the tunnel earthing system to avoid strn,y cu,rrents. The traction return current causes longitudinal voltages in the rails, which neate a rail potential and thereby a potential difference to the platform. To prevent unacceptable contact voltages, which cannot be excluded when several vehicles start simultaneously, short-circw:ters were installed in every station between the rails and the earthing system of the station. These close if unacceptably high voltages occur and thereby protect passcugers from danger. The\ short-circuiters open after approx, lO sec, when tJw monitoring fu11ctio11 is r<'activated.
1.5.2
i
'I
!
I
Substations and co111ponents
Figtiit: .22 sho\\'s an O\'crvicw of the circuit diagrnm of the suhstatio11s. 'I'hey are
stM,ion to th<\ ;J.cl kV 11iedi11rn-voltage ring. l'l1is i11d11dl<~ ri11p,, Ill<' cinuit l>1eakcrs for the
,1 'I
I
I
NI
:,1 fl1
....
1 Traction power supply systems
66
AC 34,5 kV
DC 750V
..L
Figure 1.22: General circuit diagram of a substation of the Ankaray underground traction system .
transformer for the DC traction supply and the transformer supplying the buildings of the neighbouring station and all necessary equipment for measurement recording. The transformers supplying the current inverter are designed as in resin encapsulated types and have two secondary windings which supply voltages phase-shifted by 30 degrees. A diode rectifier is connected in a three-phase bridge circuit to each secondary winding, so that a twelve-pulse direct current results at the DC side. The protection devices reliably and selectively detect short-circuits, by measurment of absolute current value, current change speed (di/ dt) and surge heights. Rapid DC czrcu:it breakers with quenching charnbers cut off the short-circuit currents on the line after being triggered by the line protection.
1.6 References_ .
1. 6
67
References
I.I Sa.chs, K.: Die ortsfosteu Anlageu elektrischer Balmen (The fixed installations of electric railways). Orell Fiissli Verlag, Ziirich - Leipzig, 1938. 1.2 K11111mcr, W.: Die Maschinenlehre der elektrischen Zugforderuug (A theory of machines for electric railway traction). Verlag von Julius Springer, Berlin 1920. 1.3 Koe/;/;11i/;y;, H.; Winkler, G.; WeBnigk, K.-D.: Gruudlagen elcktrischer Betriebsvorg~inge iu Elektroeuergiesystemen (Basic principles of electrical operation procedures within electrical power systems). Deutscher Verlag for Grundstoffindustrie, Leipzig, 1986. l.4 Schmidt, P.: Energieversorgung elektrischer Bahnen (Energy power supply of electric railways). Verlag transpress, Berlin, 1988. 1.5 VEM-Handbuch: Energieversorgung elektrischer Bahnen (Energy power supply of electric railways). Verlag Technik, Berlin, 1975. 1.6 Braun, E.: Stromversorgung der Hochgeschwindigkeitsstrecke Madrid-Sevilla (Power supply of the high-speed line Madrid-Seville). In: Elektrische Bahnen 88(1990)12, pp. 415 to 427. 1. 7 Braun, E.: Connection of railway substations to the national three-phase power supply for the Madrid-Seville high-speed line. In: Elektrische Bahnen 88(1990)5, pp. 215 to 216. 1.8 Elektrischer Betrieb bei der Deutschen Bahn im Jahre 2000 (Electric operation of German railway in 2000). In: Elektrische Bahnen 99(2001)1/2, pp. 3 to 34. 1.9 DB: German railway directive Gbr 995: Schaltanlagen for Balrnstrom (Substations for railway power supply), Herausgeber DB Netz AG, NGT 54, 01.05.1997 1.10 Nieka.mp, [(.: Das Unterwerk Weiterstadt, die erste Schaltanlage der Deutschen Bunclesbahn mit 40-kA-/16,7-Hz-Vakuumschaltern (The substation Weiterstadt, German Railway's first substation with 40 kA 16,7 Hz vacuum circuit breakers). In: Elektrische Balmen 82(1984)5, pp. 163 to 165. 1.11 vVit;tke, V.; Ba.uer, G.: Standardisierte Bahnstromsc:l1alt;-udagen olrne zeutrale Druckluftversorgung bei der Deutschen Bundesbahn (Standardised traction power substations without central compressed air supply at German Railway). In: Elektrische Bahnen, 83(1985)8, pp. 246 to 249. 1.12 ]Vfaul, D.; Stei11e11wr, N.: Vakuum-Leistungsschaltcr 3AF fiir l3ahustromuetze hoher Kurzschlttflleistung (Vacuum circuit breakers 3AF for traction power networks of high short-cirrnit. power). In: Elektrische Bahnen, 82(1984)5, pp. 142 to 146. 1. 1;3 Harpred1/;, \:V.: Modcrnc Aulagcu dcr l3al111stromvcrsorguug (l'viodern installations for
traction power st1pply). In: Die Dundcshalrn, (i2(1!J8G)7, pp. 499 to 505.
68
_ _ _ _ ··-·
....... l_':l:'raction power supply systems
2 Requirements and specifications 2 .1 2 .1.1
Requirerr1ents on contact lines General
The reliability of electric railway operation depends heavily on the availability and reliability of the traction power supply installation. The requirements on the contact line albeit an overhead line system or a third rail system are particularly high in this regard. The contact line is the only component in the system of the traction power supply installation which is not installed redundantly for economic and technical reasons. The high demands on contact line systems also result from their tvvin functions as: - distribution lines for the electric power over a particular distance and - provision of a sliding contact for the current collector under all conditions. The required high availability of the contact line system, therefore, necessitates thorough planning as early as practicable in the planning cycle for electrification. It should make use of mature, carefully tested equipment with long service life, correct installation and effective maintenance during operation. The following basic demands must be made on the design of a contact line installation: The installation should be sec'ure in operation and capable of high perforrnance. Persons and equipment must not be placed in any danger from the operation on contact lines. At all speeds, up to the permissible maximum speed of the contact line type under consideration, the dynamic interaction of the current collector and the contact line or third rail has to ensure interruptions to the power transmission are kept within acceptable limits. All components of the system should have a long service life. The following specific requirements are important, therefore: High mechanical and electrical strength. Resistance to loads imposed by wind and ice and aggressive s'Ubstances in the air. Corros1,on resistance of all components and Uniform, low wear of the contact wire. During the erection of overhead contact line installations in built-up areas, aesthetic and city-planning aspects have to be observed. The nature and environmental protectum have to be taken into ac:count. The investments for the installation and the costs for operatum and rnaintenance should be as low as possible d11ring the life cycle of the equipment. A review of the individual charact<~ristics d(\rived from these basic requircrncnts of a contact line system, can be classified iuLo 11wd1auical, electrical. c~nvirouruental and operational and maintenance-rdated. A. strict distinction lwt\rren the individual requi1e11w11ts is not always possible.
1:'I,\I I
I
i
1:1· ,;' J
ii;\
Iii
/1
:il.. I 'l.
11',
i
I,·
:i
70
2.1.2
___
. 2 Requirements and specifications
Mechanical Requirements
The demanded str-ength of the employed wires, stranded conductors and other elements is a basic rneclwnical requirement for a functional contact line installation. To ensure a fault free interaction of the contact line or third rail with the current collector defined clearances between the contact line or third rail and the rails have to be maintained. In regard to overhead contact lines, the contact wire position is referred to the projected centreline of the super-elevated track. The height of the contact wire above rail is specified according to the type of railway and field of application. The minimum contact wire height, the maximum contact wire height and the permissible contact wire gradient are all of similar importance. The forces in stranded conductors, wires and other components have to remain within the permissible limits under all operational conditions. The sag of conductors may not exceed the permissible values to ensure prevention of clanger to life and operations. When the required safety clearance or the minimum clearance is infringed upon, clanger is possible. Minimum air gaps to energised parts have to be maintained under all operating conditions, such as varying positions clue to passing pantographs, differing sags etc. The wind and ice loads imposed on the conductors and elements should not have a negative effect on railway operations. To ensure the most uniform as well as low wear of the pantograph collector strips and the contact wire itself, the contact wire has to be laid with a lateral o.ff:;et to the projected track centre line, called a stagger. All mechanical loads acting on the overhead contact line must be carried by the poles and foundations and transmitted safely to the ground. Deformations of parts such as bending of poles or any incurred resonant vibrations should not affect the transmission of power. Overhead contact line equipment has to comply with sophisticated quality criteria for successful power transmission. There are static quality criteria such as elasticity and its uniformity along the span and contact wire uplift. The dynamic quality criteria includes speed of wave propagation, the Doppler factor, the reflection factor etc. The contact force as a function of the running speed and its standard derivation are a significant quality feature as well. High-speed overhead contact lines, shall also be capable of allowing operation of trains with two or more pantographs in contact.
2.1.3
Electrical requirements
The type of current and the norninal voltage including the permissible deviations (see Table 1.1) are significant characteristics of electrical requirements. A signific,u1t criteria for the performance of ,u1 f~lectrifiecl line is the limit of the wrrent-co,r-ry'l:1u; capacity of the contact line system. In comparison with normal industrial electricity distribution overhead power line systems, short-circuits occur more fr~quently in contact line networks. Therefore, the slwrt-circuit current capacity of a contact line svstem is also a determining feature. In electric high-capacity tra!lsport systems, the volt.age of the conlacl lzne network has to be kept. within giv()ll lin1 its nuder all opera.Ling cir<'.lllllSLa.11c:cs. The loss<'s during
2.1 Requirements on contact; lines
power transmission have tu be kept within acceptable limits. To minimise the effects of relatively frequent faults on railway operations, contact line installations have to be divided into separately fed sections. Furthermore, it is essential that each installation is designed to allow faults to Ge quickly and precisely localised. If conductors or other components of overhead contact line installations fail, ddined fault conditions should occur which allow a correct determination of the short-circuit state8. The required insulation co-ordination is taken into account by the choice of the associated insulating materials and their design and by respecting the minimum air gaps. Suitable protective rneasures shall be taken to avoid exposing any person to the possibility of electric shock. Undesirable impacts on the supplying network of the public energy supply, e.g. harmonic freq'Uencies, asymmetry etc. should be kept as low as possible. The transmission of power through the contact line network can cause interference to, adjacent lines of all kinds through inductive, capacitive and galvanic coupling. In direct current railways, extensive measures are necessary to limit stray current corrosion. Track-to-earth voltages occurring in operation or under fault conditions may not exceed the permissible limits.
2.1.4
Environmental requirements
Contact line systems have to be designed to function in a defined range of arnbient temperature, in Central Europe from -30°C to 40°C. Lateral deflections of the contact lines are caused by wind loading, which in turn could lead to the pantograph de-wiring under extreme conditions. For this reason, contact lines have to be designed for particular wind velocities, under which operation remains possible. Beyond this, extreme wind loads should not lead to mechanical damage of the contact line installation itself. The magnitude of the wind velocities, upon which the design is IJased, is agreed with the railway company. Contact line installation may be loaded additionally by icing. These ice loads have to be taken into account in the design. Atmospheric precipita.tion, aggressive vapours, gases and dust are to be taken into account when determining the electrical values and the life expectancy of components and elements. The properties of the insulating materials and other elements in the contact line installation should not be altered by climatic impact and sv:11.liyht to such an extent that operation could he affected.
2.1.5
Require1nents of operation and 1naintenance
The expcndit1m' for the erectio11, operation and mai11t<~11,u1cc of contact line i11stallations should IH' as low as possible thrn11gho11t. th<~ c11tirc service~ lifo. The compo11ents and elements should lie reliable and requin~ little or no maintc\nance. The entire system should lw ccHtc<~ivcd for a long S<\rvice life utilising !'.UITosu,n JJ'f'Ofection '!nco.snres. FitLillgs, inslllators a!ld cm11ponc11Ls should h<' <·asily to inst.all and <~xcha11geahl<· as needed.
2 Requirements and specificat.ions
72
To minimise wear of the contact wire and the collector strips of the pantograph, extremely high demands are made on the contact pair of the contact wire and the collector strips of the pantograph. The design of the pantographs and overhead line must take this into account. If interruptions occur in the operation of the railway, pre-planning should ensure that it is possible to travel on the neighbouring tracks. At least the electrical separation of the contact lines of adjacent tracks and, wherever possible, the use of separate poles for each track should be considered. The contact line should be designed so that the periods of line closure for planned maintenance work or to repair to the contact lines and damage of track installations are minimal. Changes in the length of the contact lines and conductors caused by temperature variations, which often reach the magnitude of a metre, should not impair operation. In third rail systems, changes in the length have to be taken into account by adequately designed and sited expansion joints.
2.2 2.2.1
Requirements resulting from the track, line and operating conditions R,equirements and demands made on contact lines
Depending on the purpose of the railway system,, the operating conditions and the type of track and line will lead to different requirements and demands on the traction power contact lines. The requirements resulting from the operating conditions, are a function of the type of transportation required, i.e. local-area or long-distance traffic, of the traffic volume capacity and of the mass of the trains using the line. The track and line conditions particularly affecting the contact line design are the track design, the gauge and the geographical location of the line. The requirements of local-area traffic and long-distance traffic are discussed in separate sections.
2.2.2
Operating requirements
2.2.2.1
Main-line, long-distance traffic
The operating requirement of long-distance traffic that the raihYay has to transport trains of a given mass between two stations in the network within a given time and according to a. set schedule, is of major importance in contact line design. The contact line must be matched to the required traffic volume capacity. The tra.ffic volume capacity is a measure of the traffic that a railway line can handle. It is defined as the number of trains that actually run on the line within a given period ..A train run can be subdivided into the acceleration. steady-speed a.nd hn1 1(ing phases. These will differ and can be repeated in various sections, depending on the line geography and train type. The scheduled run, the track and the geographical location of the line also determine the permissible and required speed for which the resp
2.2 Requirements resulting from the track, line a!~~!_ operating conditions
73
---~--------------~
Table 2.1: Allocation of standard DB overhead contact line designs to maximum running speeds. Standard contact line design Re 75 1 l RelO0 Re160 1 l Re200 Re250 Re330 1) 2) 3)
2) 3
)
-------,,.,,.,,.,..''
B-Town
,. ,.
(I)
()
C
,. ,.
cu
,.
0
75 100 160 200 280 330
Secondary lines in stations Through-going main lines, secondary lines and passing lines Through-going main lines and passing lines Through-going main lines Through-going main lines Through-going main lines
not for new line construction when used by trains with two pantographs, 300 km/h with one pantograph when used by trains with two pantographs, 350 km/h with one pantograph
-~----
U)
Application
Vpcrm
in km/h
,.
,.
,. ,.
,.
,,. ,. ,,.
______ _
250
,..
t
/
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1 1brea-1 start -+___ c_on_s_ta_n_ts-'-p_e_ed_--~u_n_o~n£_:
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/
0.
en
/
Ol C
c
L~-Town
C
:::,
o+--------------------l 1245
km/h
Time-
1305
Figure 2.1: Distance-time graph of a train on a specific railway line [2.1].
~0-1-----------------------~ A-Town
Distance/Time - -
B-Town
Figure 2.2: Speed-distance graph for a specific railway line [2.1].
characteristics. In DB's (German railway) classification system, the standard contact line installation designs are allocated to specific running speeds as shown in Table 2.1. Figure 2.1 shows the distance-time graph of a train on a specific railway line. The time function of the force required to move a train depends on the line geography and the train's traction force characteristic. This is a function of the speed and curve radius. This function, the required speed and thr: related efficiency coefficients then determine the power to be transmitted via the collector (Figure 2.2). During the acceleration phase, the force required to accelerate the train is superimposed on the force required to overcome the motion resistance. Due to the typical traction-force/speed cha:raderistics of the traction vehicles, they achieve their maximum power at speeds of 80 km/h to 100 km/h. They can utiliie this power either for further acceleration or to maintain a steady speed. The power supply systems and the contact line installations must be able to supply the required power for the planned train frequency. The maximum train length will affect the length of platfonnti, of secondary and main lines in stations, of passing tracks as well as protective sections, neutral sections and
74
2 Requirements and specifications
Table 2.2: Main characteristics of tramways, urban railways and metropolitan railway systems. Characteristics Vehicle width Average speed Reserved track/ road way Distance between stations
Tramway
Urban railway
Metropolitan railway
2,20 to 2,30 m 20 to 25 km/h none < 400 m
2,30 to 2,65 m 25 to 40 km/h mainly 400 to 800 m
2,50 to 3,00 m > 40 km/h exclusively 500 to 1000 m
the location of signals. The design of the contact line installation also depends on these factors. The operating requirements and the energy supply systems of long-distance, main line traffic are the factors leading to the use of overhead contact lines as traction energy supply systems for long-distance railways.
2.2.2.2
Local-area traffic
In local-area traffic, it is distinguished between tramways, urban railways and metropolitan railway systems according to their main characteristics as shown in Table 2.2. Trolly bus lines supplement local-area railway systems. Whereas trams have to share the roadway with other road traffic, the tracks of urban railways run separately to some extent and metropolitan railway tracks are separate from all other traffic. For this reason, trams and urban railways must use overhead contact lines, whereas metros may use conductor rails or overhead contact lines. The tight, close schedules of local-area traffic, particularly at peak hours, mean that the contact lines must be able to conduct large currents. This is a characteristic of conductor rails. Overhead contact lines, formerly often installed as simple trolley-type contact wire without a catenary, are now mainly designed as catenary system installations, providing the advantages of: higher overall speeds, higher current-carrying capacity, better collector running characteristics, less collector strip wear, less dangerous behaviour in the event of contact wire breakage, and longer spans. The use of vertical catenar·y S'uspenszons is only avoided in areas where aesthetic urbanplanning and architectural aspects do not permit such systems. Then simple trolleytype contact lines with reinforcing wires or double contact wires are used instead. In Germany, the tramway operation regulations, BOStrab [2.2], permit a maximum contact wire wear of 40 %. To minimise voltage drops and the associatrcl power loss, the overhead contact lines of both tracks of double-track lines can be el<\Ctric:ally interconnrcted a.t regular intervals. Remote-controlled coupling disconnect.ors are only install<\d between the tracks on lines on which a single-track. two-w;-w emergenn· OJH'rcl!.ion must bP possible if a contact line fault should occur
75
According to the 13OStrab, the minim:urn conf;act w'ire height on lines in the open is 4,7 m. On the basis of experience gained with modern oversi7,ed road transports, most urban comrrnmities now install overhead contact win1s at heights of 5,0 to 5,5 m in the open, and approx. 4,0 rn in tunnels clue to the restricted space available. The stagger of the contact wire at the supports is usually ±0,40 m. To prevent grooves from being formed in the collector strips from localised wear, the stagger ratio of the contact wire should not be less than 10 mm/m [2.3] as the collector strip moves a.long it. The grad'ient of the contact wire: should not exceed 5 mm/m where the track gradient changes from the level to an uphill or downhill grade, and should not exceed 10 mm/m on uphill or downhill grades. In an attempt to minimise the overall line width, a central support structure is used wherever possible, i.e. the poles are located between the tracks. In local-area lines, the contact lines are mainly fed at both ends via recti.fi,er substations, ensuring adequate distribution of the peak currents when trains are accelerating and braking. The contact line disconnectors and section insulators should be located in the immediate vicinity of the substation to keep the feed cables to the cont.a.ct line sections as short as possible. The contact line disconnectors located at the contact line section insv,laton, do not need to be remote controlled. The double-end feed method has proven to be so reliable that there is no necessity to install contact line section insulators with disconnect.ors at the middle of each feed section. Other section insulators can be inst.ailed where it is desirable to maintain services on one track in case of a fault, c. g. a contact line breakage. Section insulation installations of this kind should be equipped with remotecontrolled contact line disconnectors to achieve a faster response in the event of a fa.ult. Occasional over'C'urrent relay tripping cannot be avoided when trains are nm at sight. For this reason, all contact line circuit breakers should be equipped with devices capable of distinguishing between operating overcurrent and sh01·t-circ'llit currents (see clause 11.3). vVith the ever-increasing deployment of traction vehicles able to focd braking e11ergy back into the network, voltages exceeding the nominal traction \ oltagc will occur frequently, meaning that the insulation of the contact line installations must be designed to cope vvith these increased voltages. To reduce energv loss('s and thus lower operating costs, an increase of the ovediea.d ccmtact lin<' volt ag<~ to 750 V is recommended. Transmission losses can be reduced by 5 % if the voltage is increased from GOO V to 750 V [2.1 ].
2.2.3
Require1nents due to track-related factors
2.2.3.1
Main-line, long-distance traffic
Electric lrm..r;-tlzslo:11,u: m:i.lway ndworks hav<~ their O\\'ll t.rack n'S<)n cs allowing free choice of pol<' lornt.io11. To adti<~vc 1m'clta11ical scparnt.ion of !It<' m crltcad contact lines of d011hl<'-l 1,wk li11cs. ! It<' pol<'s arc plac<)d ou t:l1<' o\l!.sid<· <)d!-',('S of the track. This
76
_____
2 Requirements and specifications
way, the German railway company DB can use a track spacing of 4,50 m for highspeed railway lines. However, separate poles may also be required on lines with more than two parallel tracks to achieve easier mechanical and electrical separation of the contact lines of the individual tracks. In this case, pole gaps between the rails are needed, leading, for example, to a track spacing of 6,40 m between main line tracks and overtaking tracks of DB railway lines. In tunnels, the overhead contact line supports can be located above and between the tracks. The track spacing is also then relevant for overhead contact line designs. The track spaci:ng usually used by the DB for train speeds up to 200 km/h is 4,00 m and for train speeds up to 350 km/h it is 4,50 m. The SNCF uses a track spacing of 4,20 m for high-speed lines. The super-elevation, which may be as high as 180 mm, the track geometry and the location of switch-points or turnouts are other important factors in the structural design of overhead contact line installations.
2.2.3.2
Urban and local-area traffic
Urban and local-area railway systems and trams often run on normal roadways without reserved space for the track. In such cases, existing buildings and structures and/ or poles specially set up at suitable positions are used as supports, and the contact line installations are designed accordingly. On lines without poles between the tracks, track spacings of between 2,80 m and 3,30 m are used on straight sections for vehicle widths of 2,20 m to 2,65 m, respectively. Poles between the tracks are frequently used on lines running on their own reserved roadway. In this case, for 2,65 m wide vehicles on tramways and urban railways, a track spacing of at least 3,60 m should be used if no safety space is required, or at least 3,90 m if a safety space is needed. Transport systems that use contact rails should always have their own track reservation.
2.2.4
Requirements due to the railway line location
2.2.4.1
Main line long-distance traffic
The demands on and design of contact line installations of main lines for long-distance traffic is very strongly influenced by the desired running speeds. The running speeds, in turn, determine the geometry and geographical location of the railway lines, especially the cur-ve radii and the associated super-elevatiou. When nr.w lines are built, the planned speeds dr.t<)rmine the radii and associated superelevatiou right from the outset. However, on existing lines, it is often necessary to increase tlw p<\rmitted running speeds to achiev
Tra:ins with f;'il/;zng bodies permit. a further inc:reas(~ of the rnnning speed by 14: % if passive tilting mechanisms arc used or by as much as 30 % if active tilting mechanisms arc nse
2.2.4.2
Local-area traffic
In local-area traffic, the operating speeds range from 80 to 100 km/h. The design of the contact line installations will not be determined so much by the train speeds as h~· the larger currents needed due to the lower traction voltage. Cun-e radii are also smaller than on main lines, the terminal loops of tramways in urban areas may have radii of 18 m. Line gradients up to 110 °/oo may also occur for adhesion-only vehicles hut on newly-planned lines, an attempt is made to limit gradients to 50 °/oo.
2.2.5
Requirements relating to the gauge
2.2.5.1
Main-line long distance traffic
The clearance gauge is of great import.a.nee in contact line design since no components of any kind are allowed to protrude into this area. The independent development of railways in various· regions in the past has led to different clearance gauges. They have been harmonized to some extent with the aid of the International Union of Railways (UIC) which aims to achieve interoperah1lit:i; of European railways. According to these agreements, the GA gauge (Gabarit A) must be maintained on all lines. This condition is met throughout the DB's network. For combined road/rail tran.sports, piqgybad: loads etc:., the larger gauges GB and CC have been defined on the basis of specific model loads on special wagons. The GB gauge is t~esignecl to accommodate tlw transport of standard shipping containers. Iu the DB railway network there are only a fow narrow sections not able to provide a G n gauge clearance. This means that nation-wid<' container transport is possible. To permit transportation of containers with a width of 2 ,G m instead of tit(' :2 .5 rn normally used up to now, the gauge variant GB 1 has been defined. A11othn \ ariant, GB2, has been defined for the 11·1gyybad: lro:nsporlal.'i.on of trni 1c'r trucks 011 special lmv wagons with a floor height of (L2, l!L Nonna! t.rncks and trailer trncks ( 11.rl1111lated lm-r·i.es) are tra.nsportcd 011 special wagons ou CC'ttain corridor lines . The (;(' gauge shown in Fig1ue 2 . :3 has h<'<'ll sp<'cificall_\' ddi11<~d for this p111posP. Th<' CC gatl!-',l' is also n)qt1in~cl to enahl<' t lw t1S<' of crn11fo1t al>i<· t!o11.!1lc-t!cd:cr 1mss1·n111·r 111a11011s 011 liiglt-spe<'d
I 78
2 Requirements and specificat~()llS
other tracks
through-going main-line tracks
8
3)
4900
1860
1860 3900
~ - - , / A - - - space for signal or line equipment between line tracks or through-going main-line tracks
2500 2200
2200
1700
1600 1275
1700 1200 1600 1275
375 TR
Figure 2.3: Infrastructure gauge GC in curves with radii~ 250 m, dimensions in mm. 1) Space for platforms, ramps, shunting facilities and signal systems. 2) Space for structural elements and facilities where these are required for railway operations. 3) see Table 2.3
railway lines. For this reason, all new railway lines for high-speed traffic in Europe will be built with GC gauge clearanC(\. In the specifications stated in the European Council Directive 96/48/EC [2.5] on the znternperalnlity of the trans-European, high-speed rail .systen1,, this gauge is recommended. Hovvever, only the GB gauge is mandatory. Figure 2.4 shows a comparison of the gauges GA, GB and GC. Table 2.3 shows additional dimension information 011 the spaces for tlw overhead contact line gauge. Figure 2.5 shows the Australian infrastructure gauge for electric main-line railways in the state of Victoria. According to t li<~se specifica.tions, different gauge dimensions apply to bridges, w,dls, O\'<'rhcad contact Jin<' polC's, lighting poles, signal pol0s a,nd platforms. C<\tH~rally, t111111ds
;111•
kr'p! to th<· 111i11i11111111 p<'rn1issihl<' cross-s<'ctionnl
,m\aS,
to limit
2.2 Requirements resulting_from the track, line and opera.ting conditions
79
7700 1100
~ I additional gauge
5700
Shinkansen, space for /
pantograph included
for pantograph
I
2000
3050 2500 2200 1900 1825 ru I ~I
E!_
600
~I 0
i51
J2
9TR
1545
Figure 2.4: Comparison of European infrastructure gauges. Table 2.3: Dimensions of the regulation infrastructure gauge for overhead contact lines in curves with radii 2:: 250 111.
Powet supply
Ratc)d voltaµ,t!
Minill llllll
lwight.
Half the minimum width b1 ) i11 the' operating height zone of the pantograph, above RH
::; 5300 // I )
I
5300 to 5500
k\
AC DC I)
I
5500 to 5900
I
5900 6500
to
Devel of c:or11crs
!.I)
I
c[ I)
llllll
400
F> 2'i
:i200 :'i:340
lcJ30 1500
1-140 1510
1470 15,10
1510 1580
300 ~\:\5
,147
< 1,5
:)()()()
;\
.'io:\O
1:315 13:_rn
1:325 l:HO
1:355 L:370
1:195 1-110
250 2:i()
:3S0 :350
ditll('llSiOilS u.
Ii.
1
S('('
Fig Ill(' :2 :1
2 Requirements and specifications
80
3000 4)
5750 4 )
A 1550
A
1550
1550
()
Jg 3660 B
0 e! C2 C1 5500 5)
cQl o
1550
,12
.,c
3800
5260 1)
1
3800
.,c ()
Jg Ql
:0 :::,
u
0
4000 3)
0 e!
3000
cQl
0
C1 C2
B
A
2400 1070
~4000 2) All dimensions in mm 1) permits operation of single stack container (3.05 m height) on standard wagon (1.25 m floor height) with 1500 V or 25 kV power 2) 4450 for interstate rail traffic, 5500 where standard overhead poles are located between tracks 3) piers between tracks shall have 3000 min clearance For concrete sleepered or slab track, clearances may reduced to 3000 min subject to Public Transport Corporation approval. 4) 6825 for interstate rail traffic 5) required for road vehicle parallel access A B C1 C2 D
new bridges. retaining walls. (other than platforms) overhead electrification structures, lighting structures signal structures, verandah eaves signal structures on interstate lines platform (passenger and goods), rail bridge girders, signal trunking
Figure 2.5: Infrastructure gauge for electric main-line railways in the state of Victo-
ria/ Australia.
construction costs. For this reason, overhead conductor rail systems are sometimes used in tunnels. Figure 2.6 shows the GC gauge with the gauge for overhead contact lines in a tunnel suitable for train speeds up to 60 km/h. It has a cross-sectional area of just 39,6 m 2 . When overhead contact lines have to pass below structures, an attempt is usually made to maintain the standard contact line height throughout. If the clearance below the structure is too low, first the system height is reduced. If this is insufficient, the contact wire height is reduced to the permitted minimum height. If it is not possible to achieve even this minimum, then construction measures will be necessary, e.g. the bridge must be raised or the track lowered
2.2.5.2
Local-area traffic
In local-area transportation systems, a much larger variety of clearance gauges is found than in main-line railways. This is a result of the separate development of individual local-area transport companies and the lack (up to now) of interoperability requirements. In Figure 2.7, the larger gauge of the Berlin underground [2.2] is shown to the left, the gauge of the Buenos Aires i\i!etro in the cr.ntre, ~tnd the gauge of the London Underground to th<~ right.
81
2.2 Requirements resulting from the track, line and 01~<1E~1.ting conditions
----------------.:::..:::.
space for overhead contact line installation (overhead conductor rail/ soffit rail)
standard infrastructure gauge for railways with overhead contact
complete space available for civil engineering measures
-------------- ---r--- -
space available for installations
1-
GC gauge /
_J
/
I(/) I~ .Y u
I£;
I I I
/
I I I I I I I I
I I
I I I I
I \ I
I I I I I I I I I
60 2l
2300 1i
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II
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0
co
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C\l
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I
1200 3)
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C\l C\l
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11
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11 11 u = 60 S =±0,00
I I
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/
/
\
'' -670
_sz___
/ / / /
''
/
-'/
/
/ /
space for cable duct
space for cable duct
-l slab tack
Figure 2.6: Tunnel with circular cross section aud infrastructure gauge GC and overhead contact raiL 1) half width of hazard zone; 2) safety margin; 3) escape route; 4) CWH = contact wire height
82
2 Requirements and specifications
a)
b)
tunnel outline
4350 4100
0
l!)
450
1225 tunnel outline
16001
j Q)
,§1
6
~
0
0)
c
~ I'-(\j
0 0
I'--
1775
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~ I track distance
31 00 a.:
Q)
Q)
l!) (\j
track distance 3550
~ Q) C C
x,
~I
x
~!
2
2950 I
I 2730
I
Figure 2. 7: Standard infrastructure gauge of the larger underground gauge in Berlin [2.2] (a), of the Buenos Aires Metro (b) and of the London Underground (c).
The increasing importance of combined operations, i.e. the use of the same track by long-distance trains, local-area trains and trams, as is the case in Karlsruhe, Germany, for instance, illustrated in Figure 2.8 needs to harmonise the gauges To enable the use of platforms by trams as well, solutions with four or three rails can be d1visaged. Figure 2.9 shows the gauge of the trams in Melbourne/ Australia. This gauge is considerably wider than the one specified by the German trnrnway operntwn regulations, BOStrab.
~_:_3__Clima.tic comljtio11s
83
DB contact wire heigh! vmax. 6700
- l
/
I
'I
S.~z_62~0_1______- _
·,
min. passage gauge for pantographs DB-contact wire lleigl1l
v 4800
~'v-'v.. fl2_0_() _ , , /V min;-4_9!5Q.
:---~--+---+---' I I I I I I
/
0
6..0 0
c.c0. (1)
ai>c (1)
E co 0. ~
Cl)
uE
I
3650 gauge boundary specifically designed for urban mass rapid transport railways
I
I
max. 5960 (151
',
I I I I I I I I
O Ol
0 a,~
>
(1)
D
(
C
co
0.
3320 (3250)
, metropolitan rail- I ' way gauge B 80 DI GFT6N
I wagon gauge I
31 0
I
11---1-3 00 I
L
\Z.~~O-~
I I I ~75
I FO _v._ _1ooo
----~~---/ ·~
--1--2_3_0_0--~-,__4_50
-i I I
2650
l
2.3.1
I _J
~9-q,5.0£Q _____ ~~J pLa!J2r_r:n__ 1
~~~ 11
,r=='·=·=1:_g'::u=i:rlr=d=-ir=o=n='\1~'+¥1':=70=1:=_l/=:::'.'./_j: '.... ___
3
2.3
I
F'igure 2.8: Infrastructure gauges of trams and metropolitan railways within the standard infrastructure gauge of the German railway company, DB AG.
Climatic conditions Te111peratures
In the design of rnntact line s,·ste111s, the dirrwtic conditions applicable for the respective territory have to he observecl. The valid tt'm1wratm<' liu1its in Central Europe are Ji,,1,_{J/i,('St f('.'ffl,J!(TU/:11:n: of t It<' ambient air 4()°C - lowest o:1T1Jne11,/, /.e'lll,JJen1J11:U'. -;3()°C . OutdorJ'f' /cm,1wrn.tun:s above :35°(' on:nr v<~ry rarely 111 C<'lltrnl Emop<', th(' a11nual av<~rages li<' lwt w<~<'tl 8°(' and 1D°C. Iu Frnn""<\ th<' ilV<'rag<' ,,du<'s m<' apprnxi111at.dy l[>°C 111 l{w;sia, tl1<~ low<'st regio11al outdoor t<'111p<'rnt11r<' is to lJ<' <·xp<'d<'d around -G0°C. Eq11ip111<'nt of rn1t door S\ st<'111s i11 th<' housings (c . g . local rn11trol l'aciliLi<'s) should not
,0°c
s1df<'r ill('\ ('lSihl<' d,llllil/.!,(' to l1111d.io11s IH'tW('('ll :F>°C a11d -!ilffOl'ding to EN (i()r)'.,rn Tll(' ,ii)()\(' st;1l('lll(~!llS ;q>ph· for ;il!itud<'S llj) (o []()() Ill ,dJ()\(' ~;(';) level.
2_ Requirements and specifications
84
170
a) -"' 0
~
5900 1)
b)
5300
~
B
B
0 Ql
-~
1520
1520
£'
4420
cQl
0
2137 1837 0
0
0
I'L()
B
C
C
-sj-
L()
B
line across . top of rails 797
:
12271
1377 : 1537 :
All dimensions in mm 1)
maximum heigth of contact wire, minimum heigth of contact wire 4030 2 ) only straight tracks A safety area
A
minimum clearence required for traffic signals
B
minimum clearance required for any permanent construction
C
minimum clearence requierd for temporary construction subject to proir arrangement with the Authority and with special operating precautions
Figure 2.9: Gauge of the Stuttgart tramway (a) and the standard gauge of the Melbourne/ Australia tramway (b).
2.3.2
Wind velocities
For the DB, the design of overhead contact lines up to 200 km/h is uniformly based on a wind speed of 26 m/s. In regions with a higher average wind speed, higher wind speeds are to be taken into account in the design of the overhead contact line systems. The design of lateral displacement of the contact wire under wind action should ensure that reliable pantograph operation remains possible until the design wind velocity is reached. If additional specifications are made in relation to the maximum wind speeds, these form the basis of design in regard to the stability of the overhead contact line system its elf. From approximately 190 000 measurements recorded over 25 years in five German provinces, it is knmvn that the wind speed is always greater than 1,8 m/s at outdoor temperatures above 35°C [2.1]. On the basis of the standard EN 50 341-3-4 applicable to overhead power lines when the standard contact lines Re 250 and R(: 330 were designed by DB the wind velocities listed in Ta.ble 2.4 can be applied. For the overlwad contact lines Re 250 and Re 330, a wi11d speed of :33 m/s ,vas appli(:d for a h<,ight 11p to 100 111 ;-1liove ground and at
2.3 Climatic conditions
85
Table 2.4: Wind velocities according EN 50 341-3-4 for Region I and II in Germany. Height above ground in m
Region I 1 l
10 20 30 40 50 60
24,3 27,7 29,6 30,9 31,8 32,8
vw:l) in m/s
Region
n2 J
27,6 31,5 33,7 35,1 36,2 37,3
1) Region I: see Figure 2.10 2) Region II: see Figure 210 3) 10-rnin-meanvalue of wind velocity 10 m above terrain surface
Figure 2.10: Wind regions of Germany [2.6].
!wights ovn 100
Ill
Table 2.5: Wind velocities vw in m/s and terrain coefficients in France. Wind velocities 10-min-mean value of wind velocity 10 m above terrain surface 5-sec-mean value of wind velocity 5 m above terrain surface
I
Region 1 l II III
28,6
33,8
38,3
37,8
44,7
50,7
0,80 1,00 1,35
0,80 1,00 1,30
0,80 1,00 1,25
Terrain coefficient Basin with surrounding hills Plain, plateau Seashore, narrow valley 1) Regions see Figure 2.11
Figure 2.11: Wind regions of France.
above ground, a wind velocity of 37,1 m/s was used.
In EN 50 125-2, wzncl ass'11:mptwns arc contained which should be observed in the design of contact line installations. Ju particular, specifications are to be maclr on the expected extreme wind velocities, their durnti0t1 and frequency, depending on the location, the h<~ight above ground and the terrain forn1ation.
111 F1a11ce, thn'e unnci rr._qwns (\xist wli<~re tht' ,vind pressure taken into account in the d<~sigu n~sults from ,vind V<)lorities of 28,G 111/s, ~3:3,8 m/s and :38,3 111/s. Beyond this, nmxi11111111 wind \docities ar<'. spccifi<'d Ii\ tli<' S:\"CF that, arc µ,n\aU•.t than the norrnal
-------------- - - - - - - _?
n_(xp1irements and specifications
wind velocities by a factor of 1,32. A further classification is made aceording to the terrain formation. Protected land, i.e. basins with surrounding hills, is assessed with a factor of 0,8. Normal terrain has a factor of 1,0. Exposed termin includes seashores, cliffs and narrow valleys. Exposed terrain has factors het,veen 1,25 and 1,35 depending on the wind region. Table 2.5 contains the individual wind velocities valid for the SNCF overhead contact lines for different conditions.
2.3.3
Ice accumulation
The accumulation of ice on the wires and conductors of overhead contact line systems will cause an additional load on these systems. Iviore details are given in in clause 5.1.4. Whereas in Germany, it is required that ice loads are taken into account, this is unnecessary for the SNCF. In Russia, in regions with extreme ice loads on automatically tensioned overhead contact lines, such a significantly increased sag has occurred that railway operations have been impeded temporarily.
2.3.4
Active substances in the air
Aggressive dust, vapours, gases and extreme levels of humidity can cause rapid contarn,ination of insulators and increased wear of components in contact line installations, particularly when these substances are combined. These active airborne s'ubstances may occur in the vicinity of production facilities which emit such substances and near the sea. These factors must be accommodated in the design of contact line systems. These substances affect the insulation co-ordination, described in detail in Section 2.5.3.
2.3.5
Lightning voltage surges
Lightning striking contact line installations can cause flashovers at the insulation leading to damage. From measurements made by DB (German railway) [2.2], it is known that one lightning stroke per 100 km of contact line in a year can be assumed in Central Europe. The probability of lightning is highly variable and also differs according to the location. Lightning intensity is measured by the keraunfr level, which is the number of clays with thunderstorms per year. A direct lightning stroke on an overhead contact line will cause lightning voltage surges. The voltage peak of these smTes can be estimated by the following empirical equation Usmax
= 82 · Jg.
kY
kA
The probability of lightning currents exceeding I 8 can be seen in Figure 2.12_ Indirect lightning voltage surg<~s occur \Yhen an overhead contact litw li<·s in the electric field between a cloud and the c•arth as lzght11:ing discharges_ \,Vhen a tl11111drrstonn approaches, a field of this kine! inclucc)s charg0.s in the ovrrheacl contact line_ The negative charges are drained to earth through the discharge resistance of thr· nHrnerous parallel contact, line insulators and t.he positiw cfong<·s ,tr() k<•pt hv th<' fidd <·mitt,
2.4 Specifications dueto the P.<1:ntograph ________
0,98 0,95 0,90
t
0,70
---- 0,40
0,20
£ 0,10 ]§ 0,03 2l 0,01
S2
(1_
87
I
\ \ \
\.
''
''
\
"
-........
- -,_
0 .0
E
0,001 50 Lightning current
100
\
0.2
Q)
kA
fs ---
150
Figure 2.12: Probability of exceeding for lightning currents [2. 7].
:t
0 0
~
---
'
40 80 120 160 kV 200 Lightning surge voltage Bi -
a
Figure 2.13: Frequency of indirect lightning surge voltages per km of electrified line and year.
cloud. If a cloud then discharges in the vicinity of an overhead contact line, the charges are released in this line and are propagated as a travelling wave along the overhead contact line. The indirect lighting impulse over voltages are lower in magnitude than a direct lightning stroke. They also rise more slowly and have less steep flanks than direct strokes. Figure 2.13 contains information on the expected indirect lightning impulse over voltages per year and their magnitude. In overhead contact line installations, impulse voltage limiting can be achieved by overvoltage protection devices. The most important overvoltage protection device is the valve-type arrestor. Since, only limited protection is possible with overvoltage protection devices, they are not used for economical reasons unless an extreme frequency of lightning exists.
2.4 2.4.1
Specifications due to the pantograph Design and functions
The pantograph has the task of transferring the power frorn the contact line to the electric traction unit. This transfer of power has to be safe and reliable both in a stationary condition for au:ciliary and convenience power a.nd for motive pmver for the operating traction vehicle. The pantograph consists of a main frame, arm, pantograph head and drive. Using tlw DSA-3;30 S pantograph with a total mass of 109 kg as an example, the design is explained briefly. This high-perforrnance pa:ntognLph is a single-arm unit [2.4] clcsigrwcl for :350 km/Ii. Tlw ·rn,ain fran1,e has a mass of 52,7 kg including the l?jting rlr-ive and du:1n.pen; . The lower arm nnd t li<' control bar has a mass of 34,G kg, the 11pper arm and head 9,J kg . The t\vo rnll<'ct 01 strips with holders have a mass or 2,9 kg each. T'hc collector h<·<1d, rnnsisting of rnll<'d,01 strip holdcr, rnll<'ctor head g11idl<· lrn .\C 2:"j k\' 1000 _:\ and for DC :J k\' :2l00 .-\. Figme :2.1-l slwws
2 Requirements and specifications
88
Maximum height (adjustable)__/il~ /
Upper operating position
0 0 0
0
CJ)
N
LL~ 8
Lower operating position
0 0
L{)
~
Lowered position / 0 L{)
0
6
L{) (".)
N
Required clearance
(".)
800
• I
2223 2553
--1
0 0
(".) ~
6 0
co
I. Design speed Voltage/current Static contact force Drive Collector strips Service life at v = 250 km/h, Re 250 Travel of individual springs Total mass Materials. main frame other elements
380-650
0
L{)
0 0
CJ) ~
6 L{) ~
.I
350 km/h 25 kV/ 1000 A 50 to 140 N adjustable Compressed air lifting drive Carbon on strip holder made of aluminium alloy 100000 km 40 to 60 mm 109 kg Stainless steel Aluminium alloy
Figure 2.14: Pantograph DSA-350S [2.4].
2.4 Specifications due to the pa.nt.ograph
89
Q)
CJ)
C
!!! CJ)
O CD
~
C 5'.
~~
11 0
ro
0
l'--
CD
N
Ol
N
II
i'
o E
+i ·cE§i.E en .Q1
~
CD
~ .gi
1!
~9~..____o . I 1450
I- · - - - 1'1150 ------i
I ,.
31100 1950
0
CD C')
a)
b)
1650
I.
1650
. I
Figure 2.15: Pantograph RBS 70 (a) and DBS-54 (b) [2.8, 2.9].
the rn.ain characteristic data of this pantoqraph. The pantographs DBS54 (DB) and RBS70 (DR) as shown in Figure 2.15 are exa!11ples for such for conventional designs. The ba.sic requirements on the interactwn of the pantograph with the contact line arc explained by Figure 2.lG. A.s a basic requirement, the collecto·r head !1lust always protrude beyond th<~ most unfavourable posit.ion of the contact wire clue to lateral movements of the pantograph and the contact line expected during 01wration. The smooth operation of the system is only possible when the contact win~ docs not leave the wo'fkfo.g ,,·an_ye of the collector he/1.d during travel. Iu uonual operatirn1, it. is essential that the contact wire travels on th<~ collect.or st.rips. The~ pa.11tograpl1 !ta.s a low<'t ,rnd npp<'l 11 orking position . The rang<' bet ween these two
90
2 Requirements and specifications
Space without clamps
I·
for incoming and ' leaving of contact wire
- 600
·- 600
I
-~
Space without clamps ·1
for incoming and leaving of contact wire
J
·i;----------------~
- 1050
-1050
Lateral stagger f the contact line 400 400
Contact horn
Collector strip at least 1030 Working range of the Jbantograph head 1450
1
)Radius Rs of soldered collector strips 6400mm
Figure 2.16: Characteristic values of the geometrical interaction of the contact wire and the pantograph (specified dimensions valid for the DB).
positions is the working range. The highest and lowest working positions lie between approximately 2800 mm and 300 mm in relation to the upper edge of the main frame.
2.4.2
Properties of collector strips
The collector strips are part of the collector head and contact directly the contact wire to transfer the power. The collector strips should have the following properties: low electric contact resistance, high melting point, good thermal conductivity, low dead weight, high compressive strength, high elasticity and low coefficient of friction in relation to the copper contact wire. Carbon collector strips, i.e. made of electro-carbon or graphite with a binder, have proven particularly favourable in relation to the copper contact wire. The DB and other European Railways operating AC systrms have completely replaced the metal collector strips used in the first half of the century with carbon collector strips. Today, the upper limit of the permissible operating current in carbon collector strips for single-phase AC railways is 500 to 700 A per collector strip. The upper limit of the perrnis..,ible operating current for a pantograph with two collector strips lies at around 1400 A. In DC r8,ilways with lubricated copper collector strips, the value of the upper permissible operating current is 1250 A per co!lc)ctor strip . If higlwr ctuTents are required to transfer the power to the traction uniL the munlwr of pant,ographs per vd1ick must be increased.
91
2.4 Specifications due to_Q1e pantograph
Table 2.6: Current capacity of collector strip in a stationary condition on a contact wire Ri 100; collector strip 42 mm wide made of BH 424, contacted by a soldered strip, load duration > 1 h, contact force 30 N. 6.P I '19Fa 1?cw Rt..oc oc 10-sn w A
50 100 200
0,3 0,4 0,45
25 33 43
30 45 60
~
1
4 18
Rt,r 19Fa
dew 6.P
transition rnsista.nce temperaturn of tJw stt ip holdet ternperat.urn of the co11Lact wire power loss
However, this has a negative effect on the contact behaviour. In high-speed trains, the power requirement for convenience and auxiliaries reaches up to 1000 kVA. This power has to be safely transferred through a pantograph on a stationary vehicle. To avoid the contact wire melting, the currents in a stationary vehicle have to be held below the permissible limits. The expert group for pantograph/contact line interaction specified in leaflet UIC 5AG (release 1992) that for example, 100 A per collector strip is permissible for the pantograph of the ICE. In measurements made in 1993, the heating of the collector strip was determined as shown in Table 2.6.
2 .4.3
Contact forces between the pantograph and the overhead contact line
2.4.3.1
Basics for static contact force
The contact force governs the interaction between the pantograph and the overhead contact line, so static, aerodynamic and dynamic contact components are discernable. The static contact force is the force exerted by the collector strips due to the force applied by the pantograph drive on the overhead contact line, measured at a stationary traction unit. To achieve the most consistent working conditions, this should be equal throughout the entire working range of the pantograph during both upward and downward movements. In practice, the friction in the knuckle causes differences between upward and downward motion. According to TSI Energy [2.18], Pantographs, the following static cnntact forces are recommended FKo = GO to 90 N for AC 15 kV and 25 kV, - FI
''
IiI
I
I
92
,.,- 2 Requirements and specifications
400
4,0 ---,----,--,----,----,
kW
i
2
350
L,, 300
1
30 2 .5
_-1----+--+---t+--Jl Cf)
<]
2,00
(/)
Q
I
\ Downwards
UpwLs\\
1,50
a,
a,
(/)
I
m
ct
cc
E
Ct
-+----+--+---J~--j
(/)
iii ~
1.5 ~
150
'\
,
2,0 ~
0...
\\
1 00
0
200
1,0
100
u>
~ -1--7"-+-F--+---t---J
~ 0,50
50
it;
0
0 0
20
40
60
80
N
100
Static contact force - -
Figure 2.17: Static contact force of the pantograph DBS 54 relative to the working height.
2.4.3.2
0
+------+---+--+--->----<
150
250 Running speed
350 km/h 450
v-
Figure 2.18: Aerodynamic resistance Rst (1) and power losses 6.P (2) of running pantograph DSA 350 S depending on the speed according to [2. 7].
Aerodynamic contact force
The sum of the static contact force and the component resulting from running speed and dependent on the aerodynamic effects, is designated as the aerodynamic contact force. This is exerted upwards vertically and measured when the collector head is held still and not touching the overhead contact line. In the high-speed range, it is intended that the aerodynamic contact force increases only relatively slowly with the speed. The aerodynamic effects on the pantograph on the front of a train in the direction of travel is greater than on those installed on the rear of the train. The pantograph at the rear end of a locomotive is therefore operated at high-speeds. The aerodynamic resistance of the pantograph has to be distinguished from the aerodynamic contact force. It is exerted by the wind in a direction opposing the running direction. The main part of the aerodynamic resistance occurs at the collector head. Figure 2.18 shows the overall aerodynamic resistance dependent on the wind velocity for pantograph DSA 350 S. The aerodynamic contact force and the resistance force in singL·-arm pantographs depends on whether the knuckle is leading or trailing. Design of the pantograph can control the resistance forces and aerodynamic contact forces.
2.4 Specifications due to the pa.utogrnph
Static
l------t
contact force
+I
Force exerted on the overhead conlacl line by the by t11e collector strip(s) due to the action of the pantograph drive
Vertical component of the aerodynamic resistance, measured al lhe collector strip when U1is is not touching the overhead contact line. This depends on the aerodynamic effect at the current speed and therefore also on the shape of the traction unit head
Aerodynamic component
-
93
I
Aerodynamic contact force
+I
Component of force caused by the dynamic properties of the overhead contact line and the pantograph, the track and the running of the traction unit
Dynamic force component
I
Dynamic contact force
= contact force
2.4.3.3
Figure 2.19: Components of the contact force.
FK
Dynamic contact force
The sum of the aerodynamic contact force and the dynamic components 'from the interaction between the overhead contact line and the pantograph is designated according to EN 50 206-1 as the dynamic contact force. In particular, this depends on the speed, the dynamic properties of the overhead contact line and the pantographs and their number and spacing. It also depends on the running behaviour of the traction unit and the quality of the track. Irregularities in the overhead contact line, e.g. discrete masses such as section insulators, create peaks in the dynamic contact force. They should be avoided if possible. The quality of the contact between the overhead contact line and the pantograph can be assessed by dynamic contact forces. To avoid arcs and also to limit the uplift of the contact line and wear of components, the contact forces should, according to the leaflet EN 50 119, l;e between System
Speed in km/h
AC AC DC DC
< 200 > 200 '.S 200 > 200
Contact forces in N Minimum l'viaximllm positive positive positive positive~
300 3GO 300 ,H)()
EN [>Cl 119 rc\quires that, in singk-phas<' AC railways and at speeds above 200 km/h, tl1c' rot1tac-t forC('S should uot exceed 2,50 \. At sectiou insulators the contact force may
94
2 Requirements and sp~cjfications
--------
increase up to 350 N. In DC railways, a permissible \·alue of 400 N is specified. As a lower limit, it is specified for both types of power supply that the contact forces should be greater than zero under all conditions. Figure 2.19 explains the individual contact force components and their relations.
2.5
Specifications on reliability and safety
2.5.1
Standards
The many and correlated factors to be obsen·ed in the design construction, operation and maintenance of overhead lines are the object of international, regional and national standardisation. Significant, currently valid standards to be observed in the design construction and operation of contact lines for electric railways are contained in the Appendix on standards. The standardisation of contact lines for electric railways is subject to constant development. A study of the standards of contact line systems and their components showed that some hundret different regulations and standards currently exist for this subject. Important standards for designers and operators of overhead contact lines are IEC 913, EN 50119, EN 50121, EN 50 122 and EN 50 163.
2.5.2
Loading and strength
During operation, contact line systems are subjected to electrical and rnechanical loads resulting from electric voltage and currents and climatic environment. All elements of the overhead contact line system shall withstand these effects electrically and mechanically by a factor k higher than the load. This factor is a safety factor in determining insulation co-ordination and the partial factor in mechanical design. If the condition loading · k
< strength
is complied with, the basic design requirements are met. The presence of electricity in the vicinity of railways poses a hazard to life, installations and equipment . Potential hazards may be: the overhead contact lrn,e-rml voltage, the operating current and the shoTt-czrcuit current, the electric _fidd, the magnetic field, rail-earth potentials. incfoced longitudinal voltages and capacitive charges. These hazards must be limited to acceptable limits b~· adequate design of installations in compliance with the rcle\·,utt standards.
2.5 Specifications on reliability and_ safoty ____ ___________ _ ------·----~--
95
Table 2. 7: Allocation of the rated volt.age and impube volt.age to the nominal voltage and overvolt.age category according to EN 50 124-1. Nominal voltage 1 l Highest Impulse voltage Rated pennaneut voltage withstand level for voltage2 l overvoltage category kV V V V
Ucrr AC 460 3 )
DC 600 750
1000
3)
1200 1500 2400 3000 6250 15000 25000 50000 I) 2
3 4
)
) )
AC/DC 530 720 900 1150 1440 1800 2880 3600 6900 17250 27500 55000
630 800 1000 1250 1600 2000 3200 4000 8000 18000 27 500 55000
III 6 8
IV
,I)
12
8 10 12 20
15 18 40
40 75 145 250
60 95 170 300
Conductor-earth voltages but conductor-conductor voltages for IT networks Highest system voltage for nominal voltages to IEC 38 and EN 50163 For train preheating equipment and point heaters Applies to overhead contact lines
2.5.3
Insulation co-ordination
fn-S'ulation co-ordination is the choice of the electrical strength of the electrical equipment, dependent on the voltages occurring in the contact line net,vork. The criteria for the necessary electrical strength is the design level, which depends ou the nominal voltage and the use of the equipment. The use is designated by the ovcrvoltage category. Correct choice of the design insulation level ensures that the equipment will withstand the necessary voltage. vVithstand voltages are characterized by th<' wave shape and magnitude of represenlative overnolta_r;es which the insuiatiou will withstand with a defined probability.
In contact line systems of electric railways, the insulation co-ordination is performed as follows: Drt('r1t1inatio11 of the ·1,mpulse voltage withstand level in relation to the nominal voltage and the ovcrvoltagc category. Contact lines and foeder line.s of derLric railways are allocated to ov<\n'olt.agc category IV according to E\ 50 l2Ll-1. Circuits which are directl,v co1111ectcd to the contact line installation l>ttf. ar<' protecLcd by direct or indirect, o·uc·n1ol/,(l,(;c profedwn demces. are ,1ssign(•d t.o m·<'rvoltag<~ cate-
96
-·······-··-·-·-· ___________ _1 Requirements and specifications
Table 2.8: Pollution severity levels and specific minimum creepage distances for insulation design IEC 60 815 system voltage as phase to earth voltage. Specific 1ninimum creep distance AC mm/kV
Specific minimum creep distance DC mm/kV l)
Light 1
28
32
Medium 2
35
40
Heavy 3
43
50
Very heavy 4
54
62
Pollution level
11 Recommended empirical values 21 see also EN 50 119, Table Al
Example of typical environments 2 l
Areas without industries and with low density of houses equipped ,vith heating plants. Areas with low density of industries or houses subjected to frequent wind and/or rainfall. - Agricultural areas. - i\Iountainous areas. All these areas shall be situated at least 10 km to 20 km from the sea and not exposed to winds directly from the sea. Areas with industries not producing highly polluting smoke and/or with average density of houses with heating plants. - Areas with heavy industrial density and the suburbs of large cities where the high density of heating systems causes contamination. - Areas with high density housing and/or industries subject to frequent wind and/or rainfall. Areas close to the sea or exposed to relatively strong winds from the sea. - Areas exposed to wind from the sea but not too close to the coast ( at least 10 km to 20 km distance). Areas generally of moderate extent subjected to conductive dusts and industrial smoke producing very thick conductive deposits. - Areas generally of moderate extent, very close to the coast and exposed to sea spray or to very strong and polluting offshore winds. Desert areas, characterised by no rain for long periods, exposed to polluting winds carrying sand and salt, and subjected to regular condensation.
2.5 Specifications _ci_1i_ reliability andsafoty
-
---- -----
---- ---------- - - - - - - - - - ' - ' -
Table 2.9: Minimum air gap for overhead contact lines to EN 50 119. Impulse voltage EN 50119 withstand level draft 2000 kV
static
dynamic
12 15 18 40 60 75 95 145 170 250 300
100
50
100 150
50 50 -
-
150
100
220
150 -
-
-
gory III. The allocation of the impulse voltage withstand level is made according to Table 2. 7. Determination of minimum air gaps as a function of the impulse voltage withstand level. A distinction may be made between permanent and temporary situations. In the case of section insulators, the distance between the active components may be reduced to 100 mm for insulations up to AC 25 k\' unless special conditions are applied. Determination of the mimmum creepage distances in using the design voltage from Table 2. 7 and the degree of contamination according to Table 2.8. This is illustrated by the example of a 15 kV overhead contact line: For an overvoltage category IV and AC 15 000 V, an impulse voltage withstand le\·el of 95 kV is to be found. This results in a minimum air gap of 150 mm and 100 mm for temporary proximity, e.g. the movement of a passing train. The nominal voltage AC 15 000 V is allocated to a rated voltage of 18 000 \·. With a pollution level 3, Table 2.8 yields a minimum creep distance of 774 mm. vVith the simultaneous effects of electric loads and electrolytic pollution, conductive paths occur on the surfaces of insulating materials, causing creep paths. Insulating materials are classified by the comparative tracking inde:r (IEC 66c!). For overhead contact lines, only insulating materials of categories I and II are penuissible. vVhen testing insulating materials, standards EN Gl 302, IEC 60 112 and IEC GO 587 are to be observed.
:
:' '
I
2.5.4
Protection against electric shocks
2.5.4.1
General protection against electric shocks
If an electric current flows through a hurnan body or the boch of an animal, a pathophysiological effect d<\Siguated as a.11 dcr:lrirnl shock or c/1:dr u·al acculent can oc-c-111.
98
2 Requirements and specifications
Dimensions are minimum values in m
I
Public areas
--?
,,,,
Electricians and persons instructed in electrical or railway technology (restricted areas)
I Standing surface
~
Figure 2.20: Clearances to accessible live parts on the outside of vehicles as well as to live parts of overhead contact line systems from standing surfaces accessible to persons for nominal voltages in excess of AC 1 kV /DC 1,5 kV up to or AC 25 kV or DC to earth (according to
«-'1,-
/ 0,5
0
lD
EN 50122-1).
It can be caused by direct or indirect contact with live parts. In design, construction and operation of contact line installations, measures are therefore required to prevent electric shocks. These preventive measures refer to protection against direct and indirect contact and are stipulated for contact line systems with nominal voltages up to AC 1000 V and DC 1500 V inclusively and systems with higher nominal voltages. The protective measures specified in EN 50 122-1 are explained below.
2.5.4.2
Protection against electric shocks by direct contact
Protection against electric shocks by direct contact can be implemented by protective clearances or protective obstacles.
Protection by clearance Standing surfaces to which people have access shall have the minimum clearance as protection against direct contact with live parts of contact line installations or live parts of vehicles as shown in Figure 2.20. These clearance have to be met under all operating conditions. In the case of protection by clearance, compliance with minimum height of overhead contact lines, booster and feeder lines above rails is required. At road crossings with a 15 kV overhead contact line, for example, the minimum clearance between the road surface and the lowest point of the overhead contact line is 5,5 m. Furthermore, under all conditions, a distance of 2,5 m should be maintained between overhead contact lines and the branches of trees and bushes. Protection by screening or guarding Protectfon against direct conb1r-t can be made by screening energised parts to prevent contact using items such as solid walls, solid wall doors, gratings and grating doors made of conductive mat(~rial Gratings should have a maximum mesh size of 1200 mm 2 . This mesh size is l<)([lliH d up to a 1tc,igl11. ()t al. least 1,8 rn if the energis
2.5 Specifications
Oil
~~liability_ aud_safety ___
---------------
99
Co11Lad wire Catcnary wire 3 Pantograph 4 Limits of the pantograph zone 5 Limits of the overhead contact line zone without catm1ery wire 6 Limits of the overhead contact line zone with cate11ery wire TR Top of rail S 11 Length of the collector strip with contact horns to DIN 43174 S1 Side movement zone of the pantograph S 2 Distance for a broken pantograph at the side (clesign-dependa11t) Sa Electrical minimum air gap to Table 2.9 y Width of the pantograph zone from the centre of the track :c Width of the overhead contact line zone z S11 - HP Sa Height of the extended pantograph above TR to DIN 43174 S4 Electrical minimum air gap to Table 2.9 S5 Vertical clearance for a broken pantograph design-dependant) S1r Height of the pantograph zone above TR Pa Height of the extended pantograph above TR HP Highest point of the overhead contact line TCL Track centre line 1 2
-----,---y
Cf)
I
Cf)
o_'°
Q_
I
y
Figure 2.21: Overhead contact line zone and pantograph zone to EN 50122-1.
than the standing area. Barriers should have a minimum distance of 0,6 m to live parts. Standing surfaces above live parts shall be solid and have to project by at least 0,5 m from the live parts on all sides. Anti-clirnbing devices are usually unnecessary.
2.5.4.3
Protection against electric shocks by indirect contact
Indirect contact is contact by persons or domestic animals with conductive parts that are not normally energised but which may become energised under fault conditions. The parameters z:, y and z of Figure 2.21 depend on national asp0.cts. The dimension :i:; amounts to 4 m at DB [2.10]. The width of the pantograph zone depends on the design and width of the pantograph S1i, lateral movements of the pantograph S1 , the dectrical clearance in air S 2 according to EN ;j() 119 and the safety clearance S:3 for the de-wired or broken palltograph S; 3• The dimension y follows from Figure 2.21 to be
(2.1)
~-----·-
100
-----
-~_!:{eq_1:1:irements and speci_ficJ.tions
----~·----· ---·-·--
rr\y m ----,---y
= 2,0
= 2,0
Pantograph zone
E
E
C')
r-.:
0
co
II
II
Overhead contact line zone
CL
I
uf
TR
1 )x
= 5,0 m inside radii
Figure 2.22: Overhead contact line zones for DB.
for R < 1000 m
For DB's contact line design Re 200 in curves > 250 m it results for contact wire heights between 5500 and 5900 mm y
= 975 + 345 + 150 + 530 = 1470 + 530 = 2000 mm
(see Table 2.1)
The height of the pantograph zone above top of rail (TR) depends on The height of the fully developed pantograph above top of rail according to DIN 43174, The clearance in air according to EN 50119 and The safety clearance for the broken pantograph at this height. The dimension z results from Figure 2.21 to be (2.2)
For DB's contact line type Re 200 at single poles with individual cantilevers it is obtained z
6500
+ 150 + 1:350 -
7300
= 700 mm
The parameters :r, y and ::: define the pantograph and overhead contact line zones for DB as presented in Figure 2.22 according to [2.10]. A particularly serious hazard occurs vvhcn components of the electrical equipment in the vicini 1 y of the railway become energised at the contact line potential, as a result of a broken or displaced overhead contact linr; or energised pantograph. Overhead contact line and pu:ntoqraph zones are, therefore, defined so that their limits will not be exceeded if an ov<)rlwad rnntact line or an (:n(:rgised pantograph were to break or de-wire. In this zorn\ cout.a
(
2.5 Specifications on_ 1elia.bili!Y ai1~_ s,1f~t.y
-
101
------------------------------
In Figure 2.21, HP is the highest position above rail head of an energised conductor under all operating conditions. The limits of the overhead contact line zone extend vertically downwards below the rail head to the surface of the ground or bridge. According to EN 50122-1 for AC 15 kV, the overhead contact line and pantograph zones depicted in Figure 2.22 apply. For third rail systems, the limits of the current collector wne are to be determined separately for each system. In third rail systems, no contact line zone is defined. The non-energised elements of electrical equipment are primarily protected by railway earthing. Railway earthing means the direct. connection of conductive parts with the rails. In DC railways, the direct connection of protective, conducting parts to the rails is to be avoided in order to reduce the hazard of stray current corrosion. For this reason, overvoltage protection devices, also known as voltage limiters, are installed between parts to be protected and the rails. By this arrangement, connection between the conductive parts and the rails would be made only if a fault occurs. In this way, the fault current is drained by bridging this previously open gap. As an alternative, all structures and poles of the DC railway can be insulated from earth and then connected directly to the rails. Instead of railway earthing of conductive parts in the pantograph zone, a screen can be provided in case of DC railways. This screen should be installed between the overhead contact line and the component and it should be earthed to the rails. The screen should have a width at least equivalent to the pantograph zone and extend longitudinally to the overhead contact line by 0,5 m over the component to be protected. Installation of double insulation (see also clause 4.6) is also an alternative for protection against indirect contact.
2.5.4.4
Protection against electric shocks caused by the track potential
In electric railways, the tracks are used as the return line for the traction return current. When trains are moving, track-earth potentials are created clue to the transmission of the electric power. They reach peak values at moving trains and at substations. Trackearth potentials are also designated in the relevant standards as rail potentials. They assume time and position-dependent values. Due to traction currents, which increase with the power of the traction unit and the improved insulating properties of modern permanent way installations such as the insulated rail or concrete slab permanent way which is rigid and ballast-free, protective measures are necessary to prevent electric shocks from rail to earth potential. The permissible rail potentia.ls and touch voltages differ between AC and DC installations. More details on this subject including design of protective rneasures an' to he found in chapter 12.
102
2 Requirements and specifications
Table 2.10: Environmental properties of modern transport resources [2.11, 2.12) Property Specific energy requirement CO2 emission NOx - emission CO - emission Hydrocarbon emission Soot-emission Areal requirement at equal performance, new constructions Noise level at 25 m distance
Unit
Car
Train
Aircraft
kWh/100-P km kg/100-P km 1 l g/100-P km g/100-P km g/100-P km g/100-P km
48,7 12,29 133 209 27 0
10,3 4,75 3,8 0 0 1,0
62,8 17,0 88 20 8
%
285 73
100 92
170
dB(A)
100-P km means that the data are related to I Person travelling 100 Ian. Notes: Car with petrol engine. For the ICE, emissions in the supplying power plants are taken into account. Over half of the space used for electrified railway lines is an ecologically valuable living space because the air along the lines is not polluted. I)
2.6 2.6.1
Environmental compatibility General
The climatic effects which have to be taken into account in the design and construction of contact line systems are described in detail in 2.3. Clause 2.5.3 addresses the problem of pollution layers. Other aspects of the interaction between the contact line installations and the environment are explained hereafter.
2.6.2
Environmental relevance of electric traction
The transport of persons and goods is undoubtedly a social necessity because it provides the basis for a high mobility of individuals and products, an effective division of production activities and a use of rmv mat0.rials not available in the domestic market, an increase in accessihlr markets. The transport process requires the lowest specific energy when performed on rails. Beyond this, transport by electric traction vehicles is the most environmentally friendly means of moving people and frrjg,ht. Table 2.10 compares importnnl properties which characterise environmental aspects of transport facilities. The en\ irnunw11Lal prnp<~rt.ies of modern aircraft and cars are cornpared \\·ith those or the Cr•1111c111 [CE t 1ai11.
2.6 Environmental conq>atibility
2.6.3
103
Land Usage
Those areas '11,SCd for installation that are concreted, asphalted, covered with gravel or otherwise surfaced can be designated as consumed land. Subsequently these areas are no longer available for other purposes. Existing railway lines have already consumed land areas. The land consumption is only increased insignificantly by the electrification of a railway line. Additional areas can be necessary for foundations. If the poles are set on areas which have already been consumed by the constrnction of the railway, e.g. on railway land, no additional land area is required for the construction of contact line installations. During construction of overhead contact lines, it may be necessary to use land temporarily for provisional roads, for construction and excavation work. After completion of the installation, these areas are returned to their initial state. By the construction of overhead contact lines on existing railway lines, the clearance gauge is extended by space for the pantograph zone. This and the overhead contact line zone, require no additional land. The land usage for new twin-track railway lines is only 36 % of that for a four-lane motorway [2.13].
2.6.4
Nature and bird protection
When electrifying railways, the relevant regional or national directives and laws with regard to nahtre and bir·d protection have to be complied with. Contact line systems are often rest and landing places for various species of birds. This is a cause of potential danger to the birds and also to the operation of the overhead contact line installation. The danger posed to birds by contact line and cantilevers plays a lesser part. Particular dangers are tension insulators and the risk of collision with the contact line equipment. In areas where resting and landing birds are often found, the installation of bird protection devices has reduced the potential hazard significautly.
2.6.5
Aesthetics
The assessment of the effects on the environment within thc approval procedures is known as an environm,cntal impact study. Such a study is required prior to the construction of ne,v lines and extension of existing railway lines. It is difficult to make an objective assessment of the effect of a contact line on the appearance of the landscape. The layout of the railway line, the height of the overhead contact line poles, the design of cantilevers, overhead contact line, equipment, reinforcing feeders and return lines interact in a cornplex 1:1amrer. Assessing the effects of the electrification of a railway line on the landscape will always be subjective. An objective assessment of the aesthdic infiuc11ce on the landscape is attempted with the aid of comput<~r programs for the thn·<·-di111<~1tsional display of objects on th<' ground [:2 :23].
I
I.
i I
!
2 Requirements and specifications
Table 2.11: Physical properties of contact wires Units Property Usual Basic Cu units units N / mmUltimate 106 N/m 2 355 strength a330 2 9 2 Modulus of kN/mm 10 N/m 120 elasticity E 10-6 K-1 Coefficient of 17 thermal expansion o: 10-3 K-1 Coefficient of 3,93 resistivity 0:20
Contact wires CuAg0,1 CuMg0,5 360 350
510 490
EN 50149: AC-100 EN 50149: AC-120
120
120
EN 50149
17
17
EN 50149
3,81
3,85
EN 50149
0,01777
0,01777
0,02778
EN 50149
S/m
56,3
56,3
36,0
EN 50149
kg/m 3
8,9
8,9
8,9
DIN 43140 [2.14]
Ws/(kg·K)
380
380
380
EN 60865-1
W/(K·m)
377
375
•)
Resistivity
1220
Conductivity
f2 · mm 2 /m S · m/mm
2
Origin Application
10- 6 n. m 10
6
K;zo
kg/dm 3
Specific mass 'Y Specific heat c Coefficient of thermal conductivity >.
2.6.6
10
3
[2.15]
Electric and magnetic fields
In the accessible vicinity of contact line systems, the greatest expected electric fields of AC 25 kV railways is 2,7 kV /m. On lines electrified with a nominal voltage of AC 15 kV in Germany, the expected values at the edge of the railway line lie at around 1,6 kV /m. The magnetic .fields in the vicinity of the railway are dependant upon the current and, therefore, on time and location. They can reach peak values up to 80 A/m for short times. Both the electric and the magnetic fields in the vicinity of electric railways are believed to be completely harmless to humans. If monitors or other sensitive equipment are operated in the \·icinity of electric railways, interference can occur. Detailed information is contained in chapter 13.
2. 7
Physical characterisitics of materials in contact line installations
As already explained in 2.5.2, the components and structural elements of a contact line installation generally have to possess an adequate mechanical and electrical strength. Exact knowledge of the physical properties of all applied materials is essential for the correct design of coutact line installations. Tables 2 l l to :2 13 list Lit<· in1portant ph\sic,d d1,1r,H·t<·ristic•; of rnat.<'rials as a basis
Table 2.12: Physical properties of standard conduct.on-;. Property Units Conductors BzlI Al Usual Basic Steel units units 2 172 Ultimate N/mm 106 N/rn 2 strength cr 687 390 650 589 10·() N / mModulus of GO 180 113 kN/mm 2 elasticity E 192 10-ci K-1 23 Coefficient of 17 11 thermal expansion a 10-:i K-1 3,81 4 Coefficient of 4 4 4,5 resistivity a20 n. mm-·) I rn 10- 6 n. m 0,02773 0,02826 Resistivity 020 0,0287 0,138 0,14 2 6 Cond ucti vi ty 35,38 7,25 S · rn/mm 36 10 S/rn •)
K,20
Specific mass ry Specific heat c
Coefficient. of thermal conductivity ,\
kg/dm 3
103 kg/rn 3
8,9
2,7
Ws /(kg· K)
380
910
W/(K·rn)
59
Origin Application DIN 48 200: Gl-wire Bz III; steel I Bz II: 7-wire; steel II DIN 48 203: 7-wire [2.lG) DIN 48203
DIN 48 203 EN 60865-1 DIN 48 203 EN 60865-1 [2.16) DIN 48203, EN 60865-1
7,8
DIN 48 200
481 480
[2.15), EN 60865-1 [2.16] EN 60865-1
67
[2.15] [2.16]
222
for the design of contact line installations. For these tables, it should be noted that the symbols which designate the individual properties are not uniform in the subjects involved. E.g. in mechanical engineering, strength is denoted with a and in concrete engineering with /3. The numeric values the rninirnum tensile .strength a, the modulus of elasticity E, the linear thermal e:rpan.sion coefficient a, the temperature coefficient of resistance n 20 , the .specific electric resistance P'2o, the .specific electric conductivity K, 20 , the density 1 , the speci.fic heat c and the thermal conduction capacity /\ can be seen from the tables. The values indexed with 20 apply for a t,ernp<)raturc of 20°c.
Apart from the specified physical prope1ti< s, the tables ctlso contain tli<'ir origin. For physical values for which d<'via.t ing specifications arc Lo h(' lo11t1d iu litcrnture, the 1
106
_____ ---------------~_Requirements and specifications
Table 2.13: Physical properties of materials in contact line installations. Units
Property
Ultimate strength a Modulus of elasticity E
Third rails Al Steel
Usual units
Basic units
N/mm 2
106 N/m 2
kN/mm
9
10 N/m
2
10-6 K-1
Coefficient of resistivity a 20
10-3 K-1
Conductivity 1-,, 20 Specific mass 'Y Specific heat c
700 ... 1080
70
23,1 12
Dmm2 /m
10- 6 Dm
3,82
0,03268
55 30
[2.17] (2.19]
10 ... 14
[2.17]
11,7
DIN 17122, [2.19]
4,7 2,81
(2.17], DIN 17122 (2.20] v6v 04.740.6
5
0,1206 0,207 0,222 0,228
Sm / mm-
')
106 S/m
30,6
150. 10 6 2. 109
l)
2)
8,29 4,5 4,83
kg/dm 3
10 3 kg/m:'l
2,7
Ws /(kgK)
920
7,87
7,9
470 W/(Km)
880
199 0,8 .. . 1,8
72 ~ 2)
50
[2.17], DIN 17122 (2.21] vov 4.740.6 [2.22] [2.17], DIN 17122 vov 04.740.6 (2.21]
2,2 ... 2,5
477 Coefficient of thermal conductivity ,\ 1l in moist soil
Origin Application [2.17] DIN17122
210
Coefficient of expansion a
Resistivity [!20
Concrete C45/55
240 290
2
Rails Steel
(2.17], DIN 17122 [2.15] (2.19] (2.17] [2.19] (2.19]
in air
origins are also indicated. The units in Table 2.11 generally are the customary units in the first column of units. For practical calculations with llnits, this often causes errors. For this reason, the customary units have been converted into basic SI units and are indicated as the basic unit or a multiple thereof in a second column. The specified numeric values of the physical properties apply for both columns of units. For the physical values in which no specifications are made in the first column of units, the basic unit is also used iu practice. For example, the electrical conductivity of contact lines made of Cu\Ig0,5: :3G S. m/mm 2 = :3G. 1() 6 S/m.
2.8 References ...
2.8
107
References
2.1 Bencard, R.: Qucrsclmittswahl von Freileitungen bei zufallig variablen Belastungsstromcn mid Urngebungsbcdingungen nach thcrmischcn and okonomischen Kriterien im fel1lerfreien Betrieb (Selection of conductor cross section for overhead power lines with randomly variable currents and ambient conditions based on thermic and economic criteria in normal operation). Ingenieurhochschule Wismar, 1985, dissertation thesis. 2.2 Wilke, G.: Neuerc Uutersuchungcn zur Uberspannungsbekampfung in clektrischen Bahnanlagen (More recent investigations to avoid overvoltages in electrical railway installations). In: Elektrische Balmen 16(1940)10, pp. 161 to 170. 2.3 Masch, W.; Eberhard, M.: Beanspruchung elektrotechnischer Betriebsmittel durch auf3ere Uberspannungen (Loading of electrotechnical equipment by external overvoltages). Lectural paper TU Dresden, 1984. 2.4 AEG /Dornier: Hochleistungs-Stromabnehmer DSA-350S (High-performance pantograph DSA-350S). 1994. 2.5 EC 96/48: Council directive on the interoperability of the trans-Emopean high-speed rail system. 1996. 2.6 EN 50341-3-4: Overhead electrical lines exeeding AC 45 kV: Part 3-4: National Normative Aspects (NNA) for Germany. 2001. 2.7 Ha1precht, W.; I
f 108
------------------------------ - - - - - - - - - - - -
2 Requirements and specifications
2.13 Strebele, J.: Zur Umweltvertraglichkeit raumbedeutsamer Bahnanlagen (Environmental compatibility of railway installations important for regional planning). In: Die Bundesbahn (1986)9, pp. 701 to 705. 2.14 Bausch, J.; Kieflling, F.; Semrau, M.: Hochfester Fahrdraht ans Kupfer-Magnesiumlegierung (High-strength contact wire made of copper magnesium alloy). In: Elektrische Bahnen 92(1994)11, pp. 295 to 300. 2.15 Technische Tabellen, Groflen, Formeln, Begriffe (Technical tables, units, formulae and terms). 1996. 2.16 Nibler, H.: Fahrleitungen ans Heimstoffen for elektrischen Hauptbahnbetrieb (Contact line made oflocally produced material for electrical main line operation). In: Elektrische Bahnen, 17/18(1941/1942)10, 12 and 1, pp. 186 to 191, pp. 258 to 259 and pp. 12 to 16. 2.17 Mier, G.: Herstellung and Anwendung von Aluminium-Dritte Schienen (Production and use of aluminum conductor rails). In: Schweizer Aluminium-Rundschau (1984)3. 2.18 EC/ AEIF: Technical specification for interoperability. Energy subsystem. Draft 2001. 2.19 Hiitte: Des Ingenieurs Taschenbuch, Band I. 28 (The engineer's hand book, Volume I, 28th edition). Wilhelm Ernst & Sohn, Berlin, 1955. 2.20 Dubbel: Taschenbuch Maschinenbau (Mechanical engineering hand book, 11th edition). Springer-Verlag, Berlin - Heidelberg - New York, 1970. 2.21 Tackmann, K.; e.a.: Ermittlung des Widerstandes je Kilometer for die Fahrschiene S49 (Determination of the resistance for unit length for a running rail S49). In: Messprotokoll der DR, Berlin, 1964. 2.22 Markwardt, K. G.: Elektrizitatsversorgung elektrischer Bahnen (Power supply of electrified lines). Transport, Moskau, 1984. 2_23 GroB, M.: Graphische Datenverarbeitung in der Freileitungsplanung - Innovative Methoden mittels Sichtbarkeitsanalyse (Graphical data processing used for overhead line planning, innovative methods based on visibility analysis). In: Elektrizitatswirtschaft 89(1990)6, pp. 260 to 271. pp. 270 to 271.
I _\
3 Traction contact line systems and overhead contact line designs 3.1
Terminology
Initial attempts to use the insulated rails, or sliding collectors along a contact wire inside a conduit running alongside the track (Figure 3.1) to transmit the power to electric railway traction vehicles were unsuccessful. Resilient overhead lines and relatively rigid conductor rails designed to eliminate electrical hazards have now become common practice. The contact line system designs are adapted to the running speed of the vehicles they supply. Conductor rails are placed either as a third rail near track level parallel to the running rails, or as soffi/; conductor rails above the track. As a result of the wide variety of requirements and the long period over which the contact line designs have developed. different terms have evolved for the same object or meaning. For this reason, the most important terms defined in EN 50 119 and EN 50122-1 are to be used in the follmYing chapters. They are: Contact lines are a system of electrical conductors used in conjunction with a sliding current collector to supply electrical energy to vehicles. The contact line system is considered to include insulators and these are classed as being part of the electrical system in contact with high voltages. Overhead contact line systems include: all overhead contact line conductors and wiring, including the catenary wire, contact wire and return current conductors, earthing conductors, lightning protection conductors, feeder and parallel feeder lines if these are installed on the same supporting structures, - .foundations, supporting slrncturc.s and any other components which serve to hold and support, align and insulate the contact wire and conductors, and switch-gear, monitoring and protective equipm.ent installed on the same supporting structure as the lines.
Figure 3.1: Couduct.or rail located i11 a coudnit. in I3uclapest tramway (Si<)tt1c11s 1891). 1
_11_0___________________ 3 Tract.ion contact line systems and overhead contact line designs
Conductor rail systems are contact lines comprising conductive rails placed at the side or under the vehicles as a means of transmitting energy to the collector. Overhead contact lines are contact lines located above or at the side of the top line of the vehicle gauge for supplying vehicles with electrical energy through roof-mounted current collector devices. Overhead lines are electrical lines whose bare conductors are supported above ground by means of insulators or other suitable means. Contact wires are that part of the overhead contact line system serving to establish contact with the current collector. Overhead contact line zone and pantograph zone are zones within which an overhead line and an energized pantograph will, within reasonable probability, remain in the event of contact line breakage or de-wiring of the pantograph. Overhead contact line type is the description of the overhead contact line in terms of the characteristics and properties of its design, e.g. stitched catenary supported. Overhead contact line standard design is the designation for a specific form of execution of an overhead contact line, e.g. the design Re200 of the DB (German Railway). Line feeders are overhead conductors which are installed adjacent to the contact lines on the same supporting structures and serve to supply energy to successive feed points. Parallel feeder lines are overhead conductors which are installed adjacent to the contact wires and are connected to these at certain intervals in order to increase the effective conducting cross-sectional area. Bypass feeder lines serve to ensure unbroken energy supply while by-passing specific switching sections, e.g. stations on a single-track stretch of railway lines. Supports are the components carrying and aligning the conductors and associated insulating elements of an overhead contact line installation. Return circuits include all conducting components which form a conducting path for the traction return current in normal operation and in case of faults. The return circuits include: running rails, return current rails, return current conductors, earthing wires, return current cahle.s and all other components conducting return currents. Track return .system., are systems in which the running rails are used as return traction current conductors and as conductors for fault currents. Earthing conductor., arc nwtal stranded conductors which bond the supports to earth potential in order to protect people and equipment in the case of insulation faults. Longitv,d'inal .span lenql;h, or span is the term used to designate the distance, in runningtrack direction, between two successive supports. Tensionzng .section lengf;h is the term used to designate the distance between two consecutive terminations of att owrhead contact line. Autorn,atic f;ensirm:in_r1 dcvue is t,lw device used to automatically maintain a constant t,<'t1sil< fotTt1L1< t li11<' within a sp<~cifi<\
3.2 Overhead contact liue types
I_
conductor rails
I
I aluminiums!flel conductor rails
traction energy contact lines
I
overllead contact lines
I
trolley-type contact line
I steel conductor rails
111
witllout stitcll suspension
overllead cconductor rail
I
lcatenary-supportedJ overllead lines
I
I
I
witll stitch suspension
vertical arrangement
llorizontal registration
conductor rail profile
rail with contact wire clamped to it
Figure 3.2: Contact line systems for electric railway traction.
to compensate for contact line length variations resulting from temperature changes. H a~f tensioning section length is the term used to designate the overhead contact line length between a mid point and the tensioning equipment. Mid point is the term used to designate the point roughly in the middle of a tensioning section where a means of fixing the position of an overhead contact wire in longitudinal direction relative to the running rails is installed. They are used to ensure that conductors do not migrate towards one end of the tensioning section. Figure 3.2 provides an overview of the different contact line systems. The following chapters describe the types and applications of overhead contact b:nes, conductor rails and so.ffit conductor rails.
3.2 3.2.1
Overhead contact line types Basic characteristics
For safety reasons, only overhead contact lines are permitt<-\d for operation at voltages above AC 1000 V and DC 1500 V. For high running speeds, above 100 km/h especially, energy transmission becomes an iucreasingly challenging task. Because of this, overhead contact lines have undergone continuous developttwnt through a wide variety of designs, b<\giuning wit.It simple trolle;1;-type overhead lines for tramways in 1881 up Lo the pn!scn t-dm· /,:1,gh-.'ipccd ovc1hcad contact lines. Tlw decisive i'cl<'Lots in this devdoprncut, process \V<·11s;lt ion a11d t 11<' !Tpe of suspension. 1
112
3 Traction contact line systems an1 overhead cont,_~ct line designs
------------------------"--·
b
Table 3.1: Geometrical data of grooved contact wires. Designation according to EN 50149
Nominal crosssectional area mm 2
AC-80 AC-100 AC-107 AC-120 AC-150
80 100 107 120 150
Dimensions (as shown in Figure 3.3) mm r a b C d
5,6 5,6 5,6 5,6 5,6
8,0 8,6 8,6 8,6 8,6
3,8 4,0 4,0 4,0 4,0
10,6 12,0 12,3 13,2 14,8
0,4 0,4 0,4 0,4 0,4
Figure 3.3: Contact wire cross section.
3.2.2
Wires and stranded conductors
3.2.2.1
Types of wires and stranded conductors
The pre-tensioned wires along which collectors travel are called contact wires. Together with the associated messenger or catenary wires, droppers and stitch wires they form the longitudinal contact line equipment. Tables 5.1 and 5.2 show the mechanical specifications, Tables 2.11 and 2.12 the physical specifications, of contact wires and stranded wires commonly used in Europe. The main purpose of the contact wires is to act as a contact slide ensuring uninterrupted transmission of electrical energy to the collectors on a vehicle's pantograph. In order to achieve a more uniform wear of the collector strips, the contact wire is aligned at alternating angles to the track axis in a zig-zag arrangement. This type of geometry is not used for trolley-bus overhead contact lines. Vehicles of this type are equipped with trolley collectors and contact shoes in order to avoid de-wirement, which might occur if a pantograph were used as such vehicles do not run on guiding rails. 3.2.2.2
Contace wires
Contact wires which have grooves on either side of the top section to enable them to be clamped by clips, are called grooved contact wires and are abbreviated "Ri" (for Rillenfahrdraht) in Germany. There are different contact wire types and cross sections to suit the different fields of application. A fiat wire profile has proved to be favourable for trolley-bus operations, as the contact shoes mounted on the trolley-bus poles also cause lateral vvearing of the contact wires. The preferred cross section for overhead contact wires is circular (Figure 3.3). The contact wire cross-sectional area selected depends mainly on the current required, the voltage stability and the tensile forces to be applied. For direct-current traction systems with operating voltages of up to 3 kV, it is usually necessary to install parallel contact wires so-called twin contact wires or double wires if high traction power is required. The current installation technology means that the cross-sectional area of overhead contact linc:s has to limited. According to EN 50 149 the maximum cross section is AC-150. Ia international practice lGl nun 2 and 170 mm 2
3.2 Overhead contc~ct, li1w type~_
--
--------
____________________________
____::_::_:::
100 ~ ('-0 I I % IACS Cu "-.j\ -- - ' - Cu-Cr-Zr Cu-Ag\ ~----80 -
---
~
\
>,
60 -
5
t::::, D
0 Cu-Mg ,
Cu-Cr-Zr-Mg \
\
40
\
-
\
C
0
u
20 0 200
Cu-Ni~,\ Cu-s/n~, I I 400
600
Tensile strength -
MPa 800 ~ mixed crystal lattice
~ deposition alloy
Figure 3.4: Conductivity of copper alloys, plotted in relation to their tensile strength and expressed in relation to the conductivity of electrolytic copper.
?-strand
19-strand
37-strand
Figure 3.5: Stranded wire cross sections.
contact wires are used sometimes. The standard EN 50 149 lists the requirements and characteristics of electrical traction contact wires. Thanks to their high conductivity, tensile strength and hardness as well as their ability to withstand temperature changes and corrosion, hard-drawn electrolytic copper and copper alloys have become the established global conductor wire material. Upon exposure to air, copper forms a hard but conductive oxide layer which does not prevent the current from flowing. This is the reason why copper, as opposed to aluminium, which forms an oxide layer of poor conductivity, is suitable as a material for sliding contacts. All attempts to use aluminium as contact wire material have failed. Alloy additives such as silver (0,1 %) or magnesium (0,5 %) serve to further improve the mechanical or thermal properties of copper wires and thus permit the application of higher tensile forces. These properties are especially important for high-speed traffic. Except for silver, the alloying metals reduce the material's conductivity (cf. Figure 3.4). The use of cadmium as au additive is uo longer permitted in most of the Europea,n countries because of the associated environmental pollution risks. Copper-clad steel contact wir-es with a bronze or copper content of 45 % -were installed in Germany along lines such as those from Nuremberg to Augsburg, near Dessau and in Silesia in the 1940's. Up to the tim(' when the copper on the contact surfaces had worn away, these wires proved to hav<~ similar mechanical characteristics to copper wires. After this, they vvore away verv quickly and impaired operating reliability [3. 1]. Nevertheless, copper-dad steel contact wires an! currently used in .Japan [3.2]. Contact wires arc worn away by th<' collectors sliding along them (cf. clauses 9.G.3.3 and 14.3.4) [:3.3]. Th<' con1hi11atio11 of contact materials among other factors, used for collectors and contact wires, aff<'c(s the rate of wear of these compoll(~nts. The low<~st rates of wear are ad1ieved using a combination copper contact wire with carbon wllcctm· str1.1;s. Steel and rnpp<~r rnllcdor strips lead to considerably higher rates of wear. Since t.l1e resulting reduction of tlw cross-sectional area of the cont;-wt wire reduces its c111r<·nL-c,111ying cap,wi(\· alld i11nc<1s<'s the t,·nsil<' stress if the fore-<' ,1pplied is not r
114
__ 3 Traction contact line systems and overhead contact line designs
the original cross-sectional area. The criterion for determining when this wear limit is reached is the cross section measured at the points which are subject to the most severe wear. The basic requirements for near-uniform wearing of the contact wires and, as a result, for a long service life, are optimum overhead contact line and collector interaction, which depend on the design and on running speed (chapter 9) as well as accurate installation and adequate maintenance (chapter 14).
3.2.2.3
Steel wires
Galvanized steel or high-grade stainless steel wires are used for pole earthing and the wind stays of the steady arms, respectively. Steel wires are used also for head spans and catenary wires.
3.2.2.4
Stranded conductors
In overhead contact line installations, stranded conductors are used both for suspension and tensioning purposes and as electrical conductors. The most common stranded wire structures are shown in Figure 3.5. A wrought copper alloy, CuMg0,5, also called Bz II, has come to be widely used. In Central Europe, the majority of catenary vYires, headspan and cross-span wires, stitch wires and droppers, which all carry heavy mechanical and electrical loads, are made of this alloy. Stranded wires of electrolytic copper, E-Cu, are mainly used as electrical connectors between the catenary wire and the contact wire, to connect consecutive tensioning sections of the contact line system and as s,Yitch-gear cables. E-Cu conductors are often used to increase the current-carrying capability of the contact line systems of DC railways. Galvanized steel conductors were also used as catenary wires, head-span and crossspan wires in early contact line installations. The main disadvantage of simple steel conductor is its susceptibility to corrosion. Flexible, high-tensile strength stranded steel conductor with bitumen protection is used for the tensioning wheel ropes \\·hich are subject to high mechanical loads. Electrical parallel feeder lines, bypass and other feeder cables, which are only subject to loading dne to their dead weight, are made of aluminium conductors. Although aluminium has a lower conductivity and tensile strength than copper, it is cheaper and extremely corrosion-resistant after the protective oxide layer has formed. In Russia, copper catenary wires comprising copper-clad wires with individual strands of copper with a steel core are ·widely used. The Cerman raihvay company, Deutsche Bahn, has only experienced negative results with copper-clad steel wires since damage to the thin, outer copper layer by the dips used during installation work led to rapid corrosion of the steel cores. Up to now no European standards exist on copper-based conduc.tors. Therefore, National Standards still apply. The most important specifications and technical delivery conditions for conductors ancl stranded wires are laid down in DIN 43 138 Flexible copper and copper alloy conductors DIN 48 201 Part 1, Copp<~r stranded conductors DIN li8 201 Part 2, Dronze strnnded conductors
1
1
- \
3.2 Overhead cont,act liue_types_________ _
115
0
Cl'.)
_O__:__O_
Figure 3.6: Single point suspension.
EN 50 182 Couductors for overhead lines. Round wire concentric lay stranded conductors, conductors made of aluminium, aluminium alloy and steel.
3.2.2.5
Synthetic ropes
Various types of synthetic ropes made of polyester acrylamide fibres are used for anchors in plastic cantilevers, bridle-and-pulley suspensious and cross spans. Ths ropes fulfil mechanical and insulating functions. Standard pr EN 50 345 centails details.
3.2.3
Trolley-type contact lines
3.2.3.1
Definition and application
The term trolley-type contact line is applied to systems that do not have a continuous catenary wire and thus have a very simple structure. In comparison to catenary-type overhead contact line installations, the contact wire sag of systems of this kind is large, and the distance between supports must be kept short in order to meet the requirement that the height of contact be as nearly constant as possible. The rnnning speed of these systems, 80 km/h at the most, restricts their application to tramways, trolley-buses, industrial railways and turn-outs and sidings of main railway lines.
3.2.3.2
Single-point suspension with fixed a11chored contact wire
vVith s1:nglc-JJoinl s·us7Jensions, the contact wire is fixed only by a contact wire clip directly mounted on a cross-span wire or cantilever support (Figure :3.6) _ In spite of the short support spacing of a.pproxirnately 30 ttl, a sag of up to 0, ! 111 is observed at the span U!11ters of tlti~; Lype of contact line due to the lack of a rned1a11isrn to compensate for tempcrat t1rc'-dcpc~11deut, cont,;-tct wire length Yariatio11s. As it rnoves along the contact wire, a pa:11,/;01rrnph-t.:1nw ('.()l/ccloT is subject to large vertical oscillatious, while trolley collectors arc s11hj<)ct. to both horizontal and ,·c,rtical oscillat,ions. T'lw sudden change of clircctio11 i11 vc'rtical 1uovc1ue11t as a pantograph passes the trollc!v wire support can c,\llS<' the p;-111tog1,1pli to lio1111ce, or c;u1 l
116
3 Traction contact line sy~tems and overhead contact line ~~-~ign~
b)
Figure 3. 7: Pendant-type suspension of an overhead contact line for trolley-buses. a) overview, b) Detail A
oscillations. For these reasons, the running speed of such systems is limited to only 40 km/h. This design is used mainly on light-duty tramway lines.
3.2.3.3
Pendant-type suspension with and without automatic tensioning
The pendant-type suspension (Figure 3.7) was developed in order to avoid the disadvantages of the system described above. In overhead contact lines of this type, the contact wire is clamped, with an offset, to freely swinging dropper wires fixed to the supporting points. This improves the elasticity of the arrangement, and the rate of reversal of the vertical movement of the pantograph as it moves past the supports is reduced. Skew pendants are used to reduce the undesirably high sag of the contact wire. At the supports, these pull the contact wire alternately to the left and to the right. As the length of the contact wire varies due to changes in temperature, its weight causes the lower end of the slanted pendants to rise or fall correspondingly, thus compensating for the changes in sag to some extent. This measure allows the distance between supports to be increased to 40 m. To avoid lateral wear of the contact wire and prevent the collectors of trolley-buses striking the clips, slanted suspensions are designed in a parallelogram or trapeze shape (Figure 3.7), enabling the contact wire to assume the desired position even if the pendant rotates. However, the resulting zig-zag path of the contact wire leads to uneven movement of the trolley-collector. The maximum permitted running speed is less than 50 km/h.
3.2.3.4
Bridle-type suspension
With this type of overhead line design, two dips connc'.ct the contact wire with a bridle wire which is free to move in a longitudinal direction in a slub:n_q rno'unt or pulleysheave fixed to the cross-span or cantilever support (Figure 3.8). At the termination poles, the contact wire is joined to a tension adjustment medianism which compensates for contact wire length variation. The reduction in n1c1xi11rnrn mid-span sag achieved in this way allows the support spacing to 1><' itl(T(\itsed to 5:"i ni. \T<'V<'rtheless, the lack of
3.2 Q~erhcad contact line types _
pull-off lever
pulley sheave
117
stitch rope
rp/ ----~-L_.
Ct;
contact wire clip
J
Figure 3.8: Bridle-type suspension.
1400
rubber spring components
Figure 3.9: Elastic support.
elasticity and concentration of masses at support points are disadvantageous and cause increased wear at these points, limiting the running speed to 60 km/h. 3.2.3.5
Elastic supports
Elastic supports or elastic cantilevers are designations given to a cantilever design
with an elastic mounting using rubber spring components (Figure 3.9) that damps contact wire movement as well. Either single contact wires or twin contact vvires can be mounted in the contact wire clips. If elastic supports are the only means used to support a contact wire, their spacing should not exceed 15 m. It is possible to use this form of suspension for running speeds of up to approximately 100 km/h. An additional catenary wire clip permits the installation of a catenary wire and thus extension of longitudinal spans to 30 m. Elastic supports are mainly used in tunnels where the space for the contact line installations is limited.
3.2.4
Trolley-type contact line with stitch suspension
The trolley-type contact lines with stitch sv,.spension is a simple contact line design, where the contact wire is joined to the support with a st'itch-wire (also known as a bridle) arranged in a triangular shape (Figure 3.10). The first overhead contact line installations of this type, which had suspensions based on patents dating back to 1895 support
a)
I
1/3 /
I
1/3 /
-1---__'.~~i ___ --1
!------------·-·· - - - - - 1 b)
~ 1-----1------- -------------1-~ -1 3/5/
1-
I
Figure 3.10: Overhead coutact line with stitch wire suspc11si011. a) L0ttg-dista11ce li11cs b) Local lines
118
and 1907, only had short stitch-wires without droppers. They were installed with a lateral pull, similar to slanted pendants that provided a certain degree of automatic compensation for thermal expansion and contraction of the contact wire and reduced wind deflection. In addition, stitch wires can compensate for elasticity variations along the contact wire, which in turn improves the transmission of the current. Depending on the stitch wire lengths, the number of droppers between contact wire and stitch wire and on the tensioning method, it is possible to achieve running speeds of up to 80 km/h with support spacings of 65 m.
3.2.5
Overhead contact lines with catenary suspension
3.2.5.1
Basic design
Overhead contact lines with catenary suspension are characterised by one, or in some cases two, supporting catenary wires located above the contact ,vires. The catenary wires support the contact wires by means of droppers. Because of their relatively simple design and favourable running characteristics, overhead contact line installations of the catenary design have become commonly used world-wide. They permit larger support spacings than trolley-type contact lines and reduce contact components wear, they are also being more frequently installed in urban mass transit transportation systems. It is possible to classify overhead contact line equipment according to the design of the tensioning system used. A distinction is made between completely compensated contact lines with either combined or separate contact wire and catenary wire tensioning mechanisms and semi-compensated contact lines which have fixed, uncompensated catenary wires and compensated, i.e. automatically tensioned, contact wires. Usually a single contact wire is used for single-phase AC railways. For DC railways with heavy current load requirements, the associated large currents often make it necessary to use t\\·in contact wires. Supports may be individual poles, flexible cross-span arrangements or rigid portals (cf. chapters 4 and 7). To suit the different applications, various catenary type contact line designs have evolved, differing mainly in the arrangement of the individual conductors and ·wires, in the design of supports and in the permitted running speed.
3.2.5.2
Contact lines with droppers at the supports
The simple catenary-s'upported one·rhead contact l'ine designs used on early <~lectrification projects were semi-cornpensatcd and d1arncterised by a dropper connecting the contact wire to the catenary wire at or in the imnwdiate vicinity of the support (Figure 3.11). Additional droppers \\·ere i11stall<\d at. spacings of 8 to 12 m along the longitudinal span. In comparison to trolll'v-tvpc~ ov<\rhead contact lines, this syst(itn permitted the use of larger support spacings. Due to the fixed anchoring of thr. catenary wire at tlw ends and the rigid conuc'ctio11 of t.lw c,mtilev<\rs to the poles, thcrrna.l expansion aud contraction of the ca,kn,u\· \\'ire• st.ill lc•d to consiclcrahle variations in t.he height of the contact win\ in this desigll \\'lt<'t<·r1s tlH' (,\l,<~11,nY win' nuder tensile force in
3.2 Overhead contact line types ___ .. _____________________
---------·-· _ _ _ _ _ _ _ _ _ _ _1_1_9
support
1---,
dropper spacing
system height
catenary wire
I
dropper
longitudinal span i-----s-up_p_o_rl-sp_a_c_in_g_ _ _ _ _ _ contact wire
T:Ir1
1717T 63,0m
Figure 3.11: Contact line with droppers at, the supports.
Figure 3.12: Contact lines with offset droppers at the supports.
combination with the droppers ensures elasticity along the span, the elasticit:,· at the supports is inadequate, leading to great elasticity variations along the span.
3.2.5.3
Contact line with offset support droppers
The contact line with offset support droppers avoids the disadvantages described in clause 3.2.5.2, by eliminating the droppers in the immediate vicinity of the supports were eliminated and droppers at a distance of 2,5 to 10 m from the support points were introduced between catenary wire and contact wire (Figure 3.12). To reduce temperature-related changes of the contact wire height, completely compensated contact lines are used. In this case, the contact line is anchored approximately at the middle of the tensioning section by means of mid-point anchors then put under tension at both ends by tensioning equipments. These comprise tensioning-wheels or block and pulley arrangern.entcs with counter-weights to wind or unwind the wires as they expand or contract because of temperature changes, thus ensuring near-constant tensile forces. Instead of having cantilevers rigidly arranged to the poles, as is usually the case with semi-compensated overhead contact line installations, cantilevers usi11g this design are fixed to the poles by mea11s of hinges which allow the cantilevers to follow the longitudinal contact line movement, which increases in proportion to the distance from the mid-point. Applications of this type of contact line design include main-line railways with running speeds up to 120 krn/h, e.g. using the DB's Re 100 standard desigu, as well as tramways. Versions of this overhead c-ontact line system with increased tensile forces a.nd dropper spacings of approximately G m are also in use on high-speed lines, <'. g. in France.
3.2.5.4
Contact line with stitch suspension
The ten11 shid1. urire is used to cfosignate a connecting d('uieut inserted between the cateucu-_v wir<' ,llld the contact ,vire ( Figure 3.13). In sr,n1,i-r:m11,7w11.s11.led overhc(l,d contact lznes, it serves to rnrnpeusaU· contact wire height diffor<'llC"<'S i>d.we<'tt the mid-span and th<) sttpports. \\']1<~11 1.<~1t1p
120
pull-off support
stitch wire Bz II 25 mm 2 F = 2,3 kN
push-off support
J
i-------'--"--'"'-'--'-'----_,•-1
calenary wire Bz II 50 mm 2
F
= 10 kN
E -10,0m
E 0
U") U")
II I
TR
s
0
I
I I
contact wire Ri 100 /F
0 OJ_ ~
10 kN
I
I.
max. 80,0 m
Figure 3.13: Re 200 overhead contact line with different stitch wire lengths.
where the stitch wire is fixed to the uncompensated catenary wire, in conjunction with the change in catenary wire length and tensile force, causes the contact wire at the support to be raised and lowered similarly to the height changes at the middle of the span. The spring effect of the stitch wire achieves a considerably better match of the elasticity at the supports to the elasticity at the mid-span. It is the latter effect which is the main reason for the current use of stitch wires in completely cornpensated overhead contact line installations. Depending on the desired running speeds, the individual standard overhead contact line designs of DB are fitted with stitch wires with lengths of 6, 12, 14, 18 or 22 m and with one to four stitch-wire droppers. DB's standard designs Re 160 and Re 200 have a special characteristic in that the registration arm is joined to a dropper fixed to the stitch wire. In the Re 200 design, the different spring effects of short registration arms on pull-off supports and long registration arms on push-off supports is taken into account by the use of either 18 m or 14 m long stitch wires with four or two droppers, respectively (cf. chapter 4). At pull-off supports, the lateral force exerted by the contact wire is directed away from the pole. At push-off supports it is directed towards the mast. The stitch wire tension is selected with the objective of reducing variations in elasticity along the line. Stitched contact lines require careful adjustment; this can be facilitated by the use of appropriate special tools (cf chapter 14). Propert..:i designed stitch wires considerably improve the running characteristics of overhead contact line installations ( cf. chapter 9) and by allowing longer support spacings, result in lower investments. Together with high tensile forces on the cont.act and catenary wires, the use of st.itch wires is one of the characteristic- features of modern, long-wc~aring, hu;h-speed overhead
3.2 Overheadcontact _line types
121
a)
I
~
catenary wire
~
----------
I
---~
dropper
1
I
I
b)
I
catenary wire
Figure 3.14: Inclined overhead contact lines along straight track. a) semi-inclined b) fully crooked catenary wire
_ ; ? '_ _ _ _ _ _ _
-----------------contact wire / / track centre line
I
\ \
I
I "-
Figure 3.15: Inclined overhead contact line in curves.
contact lines. It is possible to achieve running speeds of up to 400 km/h with this type of overhead contact line installation.
3.2.5.5
Contact line with inclined suspension
In many overhead contact line designs, e.g. standard designs Re 250 and Re :330, the catenary wire is located vertically above the contact wire. However, along straight stretches of track, the catenary wire can also be aligned with the track centre line and the contact wire can still be arranged in the usual zig-zag arrangement. The lateral position is then affected by the alternating lateral pull. This principle is applied in DB's standard designs Re 100 to Re 200 along straight stretches. This design is also called a contact line with semi-inclined suspension (Figure 0.14 a). In inclined catenary overhead contact lines, both the contact wire and the catenary wire are off-centre. These are pulled to opposite sides of the center line along straight stretches hut both cm the same side in curves, whereby the catenary wire is further off-centre t ban the contact wire. Depending on the catenarv wire arra.ngement, this design is also called a se·mi-lwT'izonf;a,l contact h:11,e e.rr11,1.7nn.ent.. This <~nables adjustment. of the cont act ,vire position to match the track curvature and the nse of longer support spacings. Figure 3.1[> shows the arrangement of the catenary and contact wires in a curve. Overhead co11t;-1ct lirw installations of this tv1w ar<' rdativdy rare and an' used mainlv on molmLai11ous strct.dws ,vith tight bends. Tlw adjust111e11t of the contact line equipment in
.. --~T_i:action contact line s.yster!1~_ an
a)
/4 J
b)
c)
'l!Jt 'l f ~'l /
lilted
position
II I
contact wire
Figure 3.16: Contact line system with elastic dropper elements. a) Arrangement in contact line; b) Dropper with lever element: c) Dropper with spring element
such designs requires considerable effort. If higher tensile forces are exerted on the catenary wires and contact wires, the advantages of inclined overhead contact line suspensions become less pronounced. Some examples of contact lines in which a stitch wire is arranged on the side opposite to the contact and catenary wire offset are known, such as the one built on the Leipzig-Halle line in an unsuccessful attempt to achieve longitudinal span lengths of 100 m [3.4].
3.2.5.6
Contact line with elastic dropper elements
Elastic dropper elements are used to equalize the elasticity along the length of a span. A design [3.3] involves connecting the droppers to the ends of levers which, in combination with the catenary wire being given a defined twist, achieve additional elasticity effects (Figure 3.16 a) on the contact wire suspension. The length of the levers is increased adjacent to the supports in order to compensate for the otherwise lower elasticity there. Spring elements directly forming part of the droppers (Figure 3. 16 b) are used for similar purposes. Due to the higher material, adjustment and maintenance effort required designs of this kind are still seldom used, however the Swiss railway company SBB [3.5] employes such overhead contc1Ct line designs. 3.2.5. 7
Contact line with auxiliary catenary wire, compound contact line
A cornpound contact l1,nc has a second ca.tenary wire, called the cm:rifrary r:atenary wir-e between the main c:atenarv wire arnl the contact wire. It is joined to the main catenary wire and the contact. win·s hv means of droppers which lidps to eliminate
3.2 Overhead contact line types
123
~ I
I
Figure 3.18: Semi-horizontal contact line.
Figure 3.17: Contact line with auxiliary cat<'nary wire compound contact line.
Figure 3.19: Fully horizontal contact line. a) top: horizontal contact line for trolley-buses, support spacing -'15 m; bottom: horizontal contact line for trolley-buses, support spacing 60 m; b) top: horizontal contact line for trolley-buses, support spacing 35 to 55 m: bottom: horizontal contact line for trolley-buses, support spacing 50 to 75 m
variations in elasticity (Figure 3.17). This overhead contact line design was first used by Siemens in 1912. Currently it is used for DC 1,5 kV owrhead contact lines in France and for high-speed railways in Japan (cf. clause 4.8.2.3). However, the good running characteristics of this type of installation are offset by the increased material requirements and significant higher installation effort.
3.2.6
Horizontal catenary overhead contact lines
In horizontal caf;ena:ry contact lines, the individual suspension wires and contact ,,vues are in a more hori:;mntal position relative to each other. Th<'S<' s_, stems arc not as strongly deflected by wind enabling lower structure heights and longer support spacings (Figures 3.18 and 3.19). However, they require greater pla1111i11g, installrttion and maintenance effort than comparable , ertically oriented catenan -supported
124
__ ____
-~_'!'_r:~_c:tion c:ontac:t line sy~t<:!EllS cl:fl(! overhead c:ontac:t line designs
b)
a)
pressed-in stud
cap nul rubber or Klingerite washer
insulated fixing
80±1,5 170
Figure 3.20: Conductor rail used by Berlin metropolitan railway (S-Bahn) in the past, steel conductor rail in according with DIN 43 156. a) profile cross section; b) fixation with plastic cover
(Figure 3.19). In earlier designs, which have direct connections to the supports, larger contact wire height variations occur when the temperature changes (Figure 3.19 a). In modern designs which have a suspension similar to a horizontal stitch wire and no cross-span wire at the support points, the contact wire clip positions are arranged in such a way that they all rise and fall to virtually the same extent as the temperature changes (Figure 3.19 b). Mechanical calculations for horizontal registration contact lines were first carried out and discussed in a doctoral thesis in 1927 [3.4]. Apart from demonstrating the advantages described above, horizontal catenary contact lines lead to automatic compensation of thermal expansion and contraction and achieve almost completely uniform elasticity. As the temperature changes, the contact wires rise or fall to an equal extent along their entire length. Other known applications include long stretches of tunnels in Russia. The maximum running speed is 100 km/h. Typical criteria for the use of this design include special installation conditions or requirements with respect to clearance above ground or wind loading.
3.3 3.3.1
Conductor rails Third rail installations
Conductor rails are the oldest form of electrical traction current supply lines for electric railways. They are used mainly to transmit energy to the electric traction vehicles in underground and urb,u1 railway systems. Of 102 direct-current railways for public mass transit systems operated with nominal voltages of up to 1000 V surveyed in 1982, 80 % used conductor rails for energy trausmission. In systems ,vith nominal operating voltages above 1500 V, overhead co11tacL lines dominat<>, having a share of 87,5 %. For 1101uinal voltag<\S above 1500 \", only <)X[Wrime11tal c:oudnctor rail systr~ms are known.
3.3 Conductor rails ________
b
C
a
------------ ----------=-12:::::'_5
d e
TR distance to track centre line 1570±3
Figure 3.21: Conduct.or rail of the Berlin metropolitan railway. a conductor rail support b clamp c porcelain insulator d conductor rail fixation e wedge f insulating cover of impregnated wood
Conductor rails are virtually rigid conductors which are installed at the side of the track on insulated mounts outside of the vehicle gauge in such a way that energy transfer in normal operation is possible while persons are protected against accidental or intentional contact. With conductor rails, current collection may be from the top, the side or the bottom of the rail. Whereas the easier-to-construct top contact design is still used in France, England and the USA, the design in which the bottom face of the conductor rail is used to transfer the traction energy to railway vehicles is the main type used in Germany, Russia, Austria and other European countries. The Hamburg metropolitan railway (S-Bahn) is one example of a system which uses side-contact conductor rails. Protection against contact with the live rails is achieved by installing insulating conductor rail coverboards with electrical, thermal and mechanical properties suitable for the respective climatic and operating conditions. The conductor rail covers are mounted 011 insulators fixed to the conductor rail fixation parts or on the conductor rail supports. Figure 3.20 shows a mounting of this type for an steel conductor rail. In the Berlin metropolitan railway system, the conductor mil supports are usually spaced at 5,2 m intervals. The actual spacing depends on the type of sleeper used and on the track superstructure and may be as large as G m. The design of a Berlin metropolitan rnilwm· conductor rail system with steel conductor ra1:ls is shown in Figure 3.21. This type of conductor rail system had been developed for the VVannsee line anrl was still in use eyen after 1950. The onh· major change was the replacement of wood as the coverboard material by a ,yeatlwring-resistant insulatinµ, material Figure 3.22 shows a system that us<'s alu'ln't:nium,-st,eel cornposite rnnrhu:tor· rn,1,ls [:3.G]. The conductor rail supports and the insulating fixing for the aluminium-steel composite third rail can be seen. The fixing is dC'sigued to pennit longitudinal rail rnovc'meut. These rails arc also covered by plastic rurntldings with uwchanical, thenmd and electrical properties to suit the rcspcctiH' e11,·iro11111c11tal conditious. Figme 3.2;3 sho\\'s the design of a s, stcui with sick ccrnt act and hollow aluminiurn. 1'.:drarlr:d n[,'ils as used b_,· Lh<' Harnh11rg 11l<'t rnpoliLan railwm· [:3. ,] .
l ,_,
'r:
3 Traction contact line systems and overhead contact line designs
200
~
E
0)
ro lf)
I
~
ti 0 ro
Figure 3.22: Conductor rail support with aluminium-steel composite rail.
----
1471 10
"' <.\! :::::
0
;'?
"'
/6
0
lf)
TR / 9
3.3.2
track gauge
Figure 3.23: Conductor rail support of the Hamburg metropolitan railway. 1 aluminium-stainless steel coextruded composite conductor rail; 2 high-grade steel contact surface; 3 contact shoes ,vith E-Cu collectors; 4 insulating coverboard; 5 maximum vertical working range of collectors; 6 standard vehicle gauge; 7 cast aluminium mount; 8 support with conductor rail insulator; 9 top level of running rail; 10 distance bet,Yeen contact surface and track center line
Types of conductor rail
Until the beginning of the second half of the 20 th century, only steel conductor rails were used. The rails ·which were being installed to the mid 1950s had a specific resistance of between 0,125 and 0,143 S1mrn 2 m- 1 . Since then, the specifications have been changed and the grade of steel used, often termed "iron", must haw a specific resistance of not more than 0,119 S1nun 2 111 1 . In order to increase the power of DC railways in mass public transport systems, alum,mi,urn-steel composite rails are being used more frequently for new lines and line conversions. Table 3.2 lists the essential parameters of several types of conductor rails. Up to now, steel conductm ·rails have been commonly used in Central Europe [3.8]. As an example, technical deliven· specifications for this type of conductor rails are given in DIN 17122, titled. St<:c,I c·o11ductor rails for electrical railways. The electrical ,md tlienwtl prnpc~rtics of co11cl11ctor rails an' discussed in chapter 11.
/ 1
3.3 Conductor rails ...
Table 3.2: Coucluctor rnil parameters and their values (resistance per unit length for new rails at 'i?air = 20 °C ). Material Soft steel ("iron")
Aluminium composite
R'
used in
1n'
A
kg/m
mm-
n/km
40 60 75
5100 7600 9200
0,0225 0,0154 0,0128
Berlin, Munich Vienna New York
6,4 15,7
2100 5100
0,0148 0,0069
Barcelona Berlin
')
U)
0
Figure 3.24: Cross section of an aluminium-steel composite conductor rail.
Aluminium-steel composite conductor rails are being used increasingly because the specific resistance of the alloy used, Al 99,75 MgSi, is approximately 3,4 times lower than that of steel and also because it has comparably good mechanical properties [3.9]. The aluminium composite conductor rails used for electric railways have the same cross section shape as the steel conductor rails. Whereas the hollow aluminium rails with a cross-sectional area of 2100 mm 2 are produced by a continuous extrusion process, the 5100 mm 2 rails are roll-milled solid profiles. Composite conductor rails have contact surfaces of stainless steel with a tensile strength of at least 500 N/mm 2 [3.10]. The aluminium-steel co-extruded composite rails have a steel-aluminium bond which is as strong as a welded connection. The stai,nles8 steel contact surface has a high wear resistance and thus a long service life. Figure 3.24 shows the cross section of an aluminium composite conductor rail.
3.3.3
Construction and operation of conductor rail installations
Conductor rails have a high mass per unit length. Table 3.2 shows that the weights of steel conductor rails are in the region of 40 kg/m. The mass per unit length of solid aluminium cornpos1.te conductor rails is 15, 7 kg/m. In order to facilitate constrnction work, steel conductor rails are supplied in 15 m lengths and al11mini111t1 composite conductor rails in 18 rn lengths. For a temperature range betwee11 80°C a11d ;300C equal to 110 K, a steel rail of the former dimensions would cxperi(~ncc a tl1r.rmal expansion of 23,3 mm ·while the l<'.ugth of the latter composite conductor rail \\'ould var,v by 4G nun. As a result of this therm.al e:1:pan,,c;ion and contraction, a compern,atiou joint is required every 45 to GO m. A unn.pen..sation joint is a coucluctor rail joint ruade with tlw aid of fish-plates iu order to allow for length changes owing to t011qH'ratmr. variations. A lonqii'/1,rfrnal 7not('(·twe J1:1:1.n11 is installed i11 the llliddlc of a section of rigidly jointed conductor rail s< d.io11s lid\\'<'<)Il t\\O cornpeus;-lt ion joints l'l1is co111JHiS<)S a st.eel rod 1
128
3 Traction contact line systems and overhead contact line designs
2250 I
350 I
I /
/
I
II
conductor rail fish-plate
L/
r--co
1.20
II
--
U) U)
150
600
r---
I'--
C\J
cenlre of conductor rail fixing
TR
I
Figure 3.25: Conductor rail ramp of a bottom-contact conductor rail installation.
which is inserted at the corresponding conductor rail support into one of the holes which are made in each conductor rail clamp. The bottom end of the rod then protrudes into a recess in the conductor rail joint. The rigid joints between consecutive conductor rails are made either by welding or with fish-plates. Joints may be bridged by bonding cables. The specifications require that the electrical equivalent conductor rail length of a joint must be less than 5 m of conductor rail. In the Berlin metropolitan railway system, fish-plates are also used to connect the conductor rails. Where the fish-plates are bolted to the rails, a zinc coating is sprayed onto the conductor rail. This type of fish-plate joint achieves electrical equivalents of 2 m conductor rail length per joint. The e.1:pansion gap in steel conductor rails is 20 mm long <:J,t an installation temperature of 15°C. The expansion gap is bridged electrically using copper leaf-type bridges with a cross-sectional area of 600 mm 2 or very flexible conductors. Due to the given track geometries, extended gaps in the conductor rails will inevitably occur along a railway line. Such conductor rail gaps are sections of track without conductor rails and must be shorter than the shortest distance between the collector shoes of the shortest operable traction vehicle. In contrast, conductor rail separations are sections of track without conductor rails and which are longer than the shortest distance between the collector shoes of the shortest operable traction vehicle. A conductor rail ramp is required at each end of a section of conductor raiL This is a sloped end-piece to the conductor rail that serves to ensure safe landing and take-off of the collector shoes in a vertical direction. A ramp of this kind is shown in Figure 3.25. In order to enable power to be switched on and off for individual feed sections, tracks or groups of tracks in normal operation, conductor rail disconnectors are required. This disconnector enables the conductor rail installation to be separated longitudinally and laterally into isolated sections. Figure 3.26 shows the design of a conductor rail disconnect.or of type SHB 4000 [3.11]. This disconnector is designed to operate at a rated voltage of DC 1500 V and a permitted continuous current of 4000 A. It is meant to be used for isolating conductor rail sections without load, however it can break currents of up to 400 A. In the course of normal operation, conductor rails wear away. Specifications for steel conductor rails used b,v the Berlin metropolit,u1 railway stipulate the following conductor rn.t.l wear that must not be exceeded [3.12]: - along suburban li1ws 10 %, ;dong li1ws in Lii<' cit\- Ct'lllT( al('cl 15 1¼1, 1
3.4 Overheacl_f9!1iluctorrail installations_________________ _
129
0 0
Figure 3.26: Conductor rail discounector SBH 4000 [3.9].
- aloug dead-end sidings 20 %. vVea,r is determined by measuring the height h (c-f. Figure 3.20) of the conductor rail cross section. Figure 3.27 shows the reb:ttion of this measurement to the cross-sectional area for conductor rails of cross section shape J-\ ;JlOO.
3.4
Overhead conductor rail installations
It is also possible to arrange traction pow<'r conductor rails above the \C:hicle gcwgc. 111 this case the system is called an overhead r:on.ducfor rn,,i,l [3.13, 3.1-1]. The llS<' of rigid conductor rails rnounted cl.bovc the vehicle' gauge in tunrwls, so-call<'d soffit r:ont!w:tor rm.ls, reduces the amount of space required lwuws<'. the nominal height of the overhead conductor rail ouly needs tu cxu·(~d th(~ t<~quired minimum contact liu<' height hy tit(~ st1111 of the track i<'Y<'l to!(:tallc<'s and installatioH tolerances, and the vertical space required for the S\'S(t'llt h<'ight is small iu rn111pariso11 to that of a catenary-type coutact line installation. This results in lower <·osts wlwn h11ildillg 11c'\\' t11t111C'ls a11d eq11ipping <'xist i11g t unrwls \\'itlt dectrical (rn('t,ior1
,,.,,~---
3 Traction contact line systems and overhead contact line designs
130
1,00
5100 5000
0,95
mm 2
0,90 "(
C
4500
.Q
0Q)
0,85
(/)
A/An
(/)
(/)
e ()
OJ
0,80
C
c
~
4000
Q)
a:
0,75
95 100 Conductor rail height h -
90
mm
105
Figure 3.27: Remaining crosssectional areas of worn A-5100 conductor rails of steel.
0 0
LO
.8
24 6
0
co
"I
II
E
OJ
·a3 .c
>-
:0 E Q) (/) (/)
Figure 3.28: Cross section of soffit conductor rail as used in Hanover.
Figure 3.29: Support for soffit conductor rails as used in Hanover.
The Hanover metropolitan railway, for example, uses bottom-contact, upright copper rails of Siemens design as overhead conductor rails. These are installed without thermal expansion compensation joints. The conductor rails are mounted along a sine-wave shaped locus so that thermal expansion or contraction will enlarge or reduce the lateral offset. The cross section of the respective copper profiles, which are mounted on supports at four-metre intervals, is shown in Figure 3.28. Figure 3.29 shows the type of support used. The conductor rail joints il,re made using fish-plates. This installation (\llahl<~s unint<\n11pted rnrrent flow at rnnning speeds of up to 100 km/h [,3. 1:3].
3.4 Overhead co11d11cto1rail im;tal_h_tt_,i(_>_n,_s________ ---·-------·---------------=1~3:.:!:1
Table 3.3: Characteristics of overhead conductor rails v+-----+-aluminium alloy 2214 mm 2 co
with clipped-in contact wire, in relation to the support spacing, according to reference [3.15]. 12 Support spacing rn 8 10 Maximum sag between supports mm Recommended maximum running speed km/h
__.-----copper contact wire
3,1
7,5
15,5
160
120
80
Figure 3.30: Cross section of an overhead conductor rail with clipped-in contact wire.
zig-zag 250 l 250
a) E E co 0
tunnel ceiling
tunnel ceiling
/
/
/
//
/
/
b) 0
l()
zig-zag 250 250
C\J
~ - tracl< contro line
1--
pivot axis 1200
Figure 3.31: Supports for overlwad coudnctor rails. a) for DC 1,5 kV a11d DC :3 kV Ii) for AC 25 kV
/''
I
132
3 Traction contact line system~_il!!.<:! overhead contact line designs
Figure 3.30 shows an overhead conductor rail design which uses a 2214 mm 2 cross section aluminium extrusion profile mounted on supports at approximately nine metres distance and into which a standard grooved contact wire is clipped when the system is installed. At a ternperature of 40°C, a combined conductor rail of this type with clippedin contact wire of type AC-107 is electrically equivalent to a copper cross section of 1288 mm 2 . In 1994, more than 100 km of overhead conductor rail were being operated by the S,viss Railways and the railways of various other countries. These overhead conductor rail systems have been proven to be suitable for running speeds of up to 100 km/h [3.14]. Figure 3.31 shows supports for this type of soffit conductor rail installation. Reference [3.16) reports that the overhead conductor rail ,vith clipped-in contact wire, as approYed by the German federal railway administration, has a short-circuit current capability of 45 kA. It can be used at running speeds of up to 120 km/h by vehicles fitted with a frame-type pantograph pan head (Table 3.3).
3.5
References
3.1 Nibler, H.: Fahrleitungen aus Heimwerkstoffen for den elektrischen Hauptbahnbetrieb
(Contact line made of locally produced material for main line electric operation). In: Elektrische Bahnen 17 /18(1941/1942)10, 12 and 1, pp. 186 to 191, pp. 258 to 258 and pp. 12 to 16. 3.2 Nagasawa, H.: Verwendung von Verbundwerkstoffen fiir Fahrleitungen (Use of composite material for contact lines). In: Elektrische Bahnen, 90(1992)3, pp. 92 to 95. 3.3 Borz, J. W.; TschekulaJev, W.E.: Oberleitung (Overhead contact line). Verlag Transport, Moscow, 1981.
3.4 Siiberkriib, M.: Technik der Bahnstrom-Leitungen (Technology of overhead contact lines). Verlag von Wilhelm Ernst & Sohn, Berlin - Miinchen Diisseldorf, 1975. 3.5 ~chwa.ch, G.: Oberleitungen fiir hochgespannten Einphasenwechselstrom in Deutschland,
Osterreich und der Schweiz (Overhead contact lines for high-voltage single phase currents in Germany, Austria and Switzerland). Verlag Wetzel-Druck KG, D- 7730 VillingenSchwenningen, 1989. 3.6 AEG: Stromschienentrager fiir elektrische Bahnen (Conductor rail support for electrical railways). 05.89. 3.7 I-faupt, R; Freiclhofer, H.: Elektrische Energieiibertraguug mit Aluminium-Verbund-
stromschienen bei der Berliner S-Bahn (Electrical energy distribution by means of aluminium steel composite conductor rails used for Berlin city railway). In: Elektrische Bahnen, 50(1979)4, pp. 96 to 100. :J.8 DIN 4J 15G: ElektrisclH! Balmen, Stromschienen, Mafk und Ketmwc\rt,e (Electric railways, conductor rails, di1rn~usions awl charn.ct,t)ristics). March 1!)78.
3.5 References ------------------------------ --------------::1"-'.=3~3
3.9 Ja,11e/;schke, K.; Freidlwfer, I-I.; Mier, G.: Eiufiihrung vou neuen Stromschienenanlagen mit Aluminium-Verbundstromschienen bei der Berliner S-Bahn (Introduction of new conductor rail installations with aluminium steel composite conductor rails at Berlin city railway). In: Elektrische Bahnen, 80(1982)1, pp. 17 to 23. 3.10 Alumiuium-Walzwerke Siugen GmbH: ALUSINGEN-Verbundstromschieneu (ALUSINGEN composite conductor rail). Edition .June 1979. 3.11 Siemens AG: Stromschienen-1\·ennschalter SHB 4000 (Disconnector for conductor rail SHB 4000). 3.12 DR-M 24.71.010: Abnutzung von Stromschienen (Wear of conductor rails). 1980. 3.13 Rosenke, D.; Uyanik, A.: Neuentwicklung einer Stromschienenoberleitung for 1\mnelstrecken (Development of an overhead conductor rail contact line for tunnel sections). In: Verkehr und Technik (1985)5, pp. 136 to 138. 3.14 Lor/;scher, M.; Urs, W.; Furrer, B.: Stromschienenoberleitungen (Overhead conductor rail lines). In: Elektrische Bahnen 92(1994)9, pp. 249 to 259. 3.15 Data of Furrer
+ Frey,
1997.
3.16 Syre, P.: Zulassung einer Stromschienenoberleitung durch das Eisenbahn-Bundesamt (Approval of an overhead conductor rail contact line by German federal railway administration). In: Elektrische Bahnen, 94(1996)11, pp. 326 to 328.
134
3 Traction contact line -sx:s!ems and overhead_ contact line designs
4 Design of contact lines arid
cross-span equipment 4.1
Overhead contact line equip1nent
4.1.1
Basic design
Figure 4.1 illustrates a typical overhead contact line design with individual poles on both sides of the tracks. This is the preferred design for main line traffic at all usual voltages and for urban transportation also. The components such as contact line, cantilevers, poles, traction power feeder lines, return current conductors and rail bonds are shown in this schematic diagram. Figure 4.2 illustrates an overhead contact line equipment supported by flexible crossspan elements as an alternative to individual pole design. Other types of cross-span equipment adopt cant?:levers across several tracks and portal structures. The structure of an overhead line equipment can be seen in Figure 4.3. It consists of individual spans, which are designed according to the application of the contact line. The contact line is divided into individual tensioning sections. Terminations or tensioning equipment are found at the ends of these sections. The tensioning equipment maintains the tensile forces in the contact wire and the catenary wire approximately constant at varying temperatures. A midpoint anchor, which fixes the contact line equipment and 3
5
~
4
/
5
/ 6
""·
~
1 Pole 2 Cantilever 3 Catenary wire 4 Contact wire 5 Insulator 6 Power traction feeder line 7 Bonding of poles 8 Rail bond 9 Track bond 1O Pole number 11 Return current conductor 12 Stitch wire 13 Dropper
7
/~~========-~~ Figure 4.1: Ovf'rlH·,1d rn11Lad li11<'S
011
individ11a.l supports nsinl--', <·onndc poles.
4 Desigr~ of c:ont.act, lines and cross-span equipment
136
1 Bolt-mounted lattice pole 2 Bolt-mounted double channel pole 3 Head-span wire 4 Catenary wire 5 Contact wire 6 Support in head-span 7 Current carrying connector 8 Upper cross-span wire 9 Lower cross-span wire 1O Insulator 11 Section insulator 12 Pull-off 13 Switching transverse conductor 14 Switching drop line 15 Disconnector 16 Switch line crossarm 17 Electrical switch mechanism 18 Pole number 19 Pole earthing 20 Pole foundation 21 Cross-span tensioning spring
Figure 4.2: Overhead contact lines supported by head-span structures.
.
~,-
half tensloolog lecgth verlapping
midpoint 1
1
half tensioning length
2345678
0
0
0
0
0
0
tensioning mechanism span length
catenary wire
system height stitch wire
dropper
contact wire
Figure 4.3: Design of a contact line section and a span.
·~ ·tt· registration arm reg1s ra 10n arm dropper with steady arm
4.1 Overhead contact line equipment ________________________________ ___________ 137
Table 4.1: Overhead contact line equipment designs. Design
Properties
Application
1
Simple overhead cont.act line equipment. without continuous catenary wire, fixed tennina.tiou or flexible tensioning
Contact wire height changes with temperature, limited span length and current carrying capacity
Light rail systems (tramways) with low electrical load, sidings on mainline railways, speed up to 100 km/h
2
Vertical contact line equipment without stitch wire, tensioned contact wire, ca.tenary wire fixed or tensioned
Contact wire height independent of temperature, span lengths up to 80 m are possible, current carrying capacity can be adapted b)· selecting suitable catenary wire and contact wire cross sections, large variation of elasticity between mid-span and support
Tramways with high electrical load, main-line railways at speeds up to 120 km/h, two parallel contact wires are often employed with DC traction supplies
3
As (2), but with stitch wire, automatically tensioned contact wire and catenary wire
As (2), however lower elasticity differences between midspan and support
lVIain-line railways with high electrical loading and speeds up to 350 km/h
4
Vertical contact line with auxiliary contact line automatically tensioned
As (3), however higher current carrying capacity and more uniform elasticity
Main-line railways with very high electrical loading and very high speeds
Number
provides along track stability is located at approximately the mid point of the tensioning length. An overlap section provides the transition between two adjoining contact lines sections. These are also known as an overlapping block or parallel spans both contact lines are suspended in parallel. The contact line must be designed to satis(y the static, dynamic, thermal and electrical requirements for each application. The influence and effect of the individual parameters on the contact line performance can be found in the relevant sections.
4.1.2
Selection of the overhead contact line design
Selection of a t;ype of overhead contact line requires knowledge of the operating p:uametcrs and must take the requirements described in chapter 2 into account. The selection can be performed as described in chapter 3. Table 4.1 contains applications for typical ovcrlwad contact line designs. An overhead contact line type is defined by the design and thus by the configuration of its components for a given applicatio11- It, follows that the overhead contact line should nlso be configmcd to provide a minimum opcrn.tional life cycle cost. The verification of tltc' suitability of a design of overhead nmtact line for a given purpose can be performed h,· tliP simnlation of the intmaction bc~twee11 tlw overhead line and tlie pantograph or ll\ canying ont. a track test.
138
_ _ _ _ _ _4_D_e_si""'-g_n o_f_~!?ntact. lines and cross-span equipment
Table 4.2: Continuous current carrying capacity of overhead contact lines for AC 16,7 Hz. Cross section of catenary wire/ contact wire mm 2 1
50/100 ) 50/1001 ) 70/120 1 ) 120;1202 )
Range of ambient temperature t
oc
-30 -30 -30 -30
:St :S t :St :S t
S +40 :S +40 :S +40 :S +40
Permitted final temperature of contact wire
Temperature range
Current carrying capacity with RL without RL
K
A
oc 40 70 70 80
420 560 670 850
70 100 100
llO
700 900 1270 1425
RL = reinforcing line feeders (240-AL1/EN50182) 1) Contact wire Cu AC or CuAg AC 2) Contact wire CuMg AC
4.1.3
Selection of conductor cross sections and tensile forces
The contact wire and catenary wire cross sections are to be kept as small as possible for economic reasons. They should be dimensioned to satisfy requirements at the lowest cost. The traction power supply system, the traffic timetable and the route profile determine the magnitude of the current flmving through the overhead contact lines. Subsequently the conductor cross sections are rated with parallel line feeders included in the design, if necessary. The electrical rating of the contact line is described in chapter 11. Table 4.2 contains information regarding the continuous current carrying capacity [4.1] of overhead contact lines for frequently adopted combinations of catenary wire and contact wire for a contact wire wear of 20 %. The mechanical rating is aimed at the maximum possible span lengths that can be implemented by adopting high tensile forces and wide pantographs. This reduces the number of supports and therefore the investments. The selection and stress analysis of the catenary wire and contact wire will be discussed in clause 5.1.3. The lateral contact wire position permitted by the useable pantograph width limits the span lengths for overhead contact lines for speeds up to 200 km/h. The determination of the span length is performed using equations (5.47) and (5.49). The elasticity of the overhead contact line system at mid span depends mainly on the span length l and the tensile forces in the contact wire H cw and catenary wire HCA. e
l
Hcvv
He\
mm/N
m
kN
kl\'
(4.1)
The factor kE is dependent upon the d()sign of the contact line. A value of kE ;::::; 4,0 is valid without stitch wires and kr;; ;::::; :3.:> with stitch win~s. The elasticity profile along the span can be calculated using computer progr;-1ms [4.2]. Materials and tensile forces have to lw scded,c\d for high-spe1cd overhead contact line systems in such a manner that the waor' prnpw1ahon 'IJelocity c is sufficieutlv high as a characteristic dynamic variable [4.:3]: c
3,GJ"C\\ = :3,G {JC\\
r·
kI I I/ II
I
(T('\\'
()cw
He\\
m~'\\ ----1-k-.'/-1-11- (4 2)
\-/-11-11_11_ 2-+--k,L,-'/-1-11-l-+--~-,
4.1 Overhead contact line equipment._________
139
------------------~
where tensile stress in contact wire, specific density of contact wire material, tensile force in contact wire and, mass per unit length of contact wire.
aew Pew Hew m~-;w
As a reference value based on empirical data [4.3], the maximum operating speed v should not exceed 70 % of the wave propagation velocity. A tensile stress of approximately 172 N /mm 2 is obtained from equation (4.2) for a copper contact wire at an operating speed of 350 km/h. The suitability of a contact line for a given speed can be established from the Doppler factor according to (9.56) L-Y
(c-v)/(c+v)
The Doppler factor should be equal to at least 0,15, or more adequately 0,20. For v = 350 km/h, it follows that c - 473 km/h for a = 0,15 and c = 525 km/h for et = 0,20. As a result, it is necessary to use contact wires of a corresponding strength. The contact wire lift at the supports and at mid span has to be limited for highspeed traffic, to values that occur with standard overhead contact line systems. Due to the higher contact forces of the pantograph and the dynamic uplift component, lower elasticities are necessary to ensure that the lift does not significantly exceed 100 mm. The elasticity should therefore be small and evenly distributed for high speeds. The requirements of limited span length and increased tensile forces follow from (4.1). The latter can be achieved by increasing cross sections and tensile stresses. The cross section of the contact wires should however not exceed 120 mm 2 to avoid discontinuities during stringing. There has been a demand [4.3] for an overhead contact line design type Re 330 with an ela,sticity e - 0,4 mm/N at mid span. This objective was achieved by the limitation of the span lengths to 65 m, the employment of a high-tensile contact wire with a 120 mm 2 cross section and a tensile force of 27 kN together with a catenary wire cross section of 120 mm 2 and a corresponding tensile force of 21 kN. This can be verified by insertion into the relation (4.1). For details see chapter 9. Parallel feeder lines are arranged in parallel to the overhead contact lines when the selected cross sections alone cannot guarantee the required current capacity and voltage stability. See clause 11.1 for information regarding the layout of feedC'r lines.
4.1.4
Selection of span lengths
Long span lengths ar<' desirable in view of investm,cnts as low as possible. Contact wires that are displaced bv wind frnm their still air position have to gmu antC'e continued S<'('llrC power Lrnusfor. D<'tcrminatiou or spa:n lenglh must rousid<'r t lw ,viud loading 1wr unit length for tlH' cout,11ct wire l~vcvv and the cateuary wire /;~\'<,, in accordance with chapter S for the a11Licipated n:gion(J,l wind vr.locity. The height of the overhead contact lin<'s ahove Lit<~ suno11uding terrain togd,her 1,,vith rnaxirn11tn regional wind V<'locit,· ddcrtni11<'S the' wind Y<'locity to Ii<' appli<'d.
140
_ _ _ _ _4_D_e_'s.....,ig,_n_o_f_co11tact lines and cross-span equipment
90
m 80
t .c
.0-
70
,-
50
r, liT
0) C
..92 50 C
rr Jr
CTl Q. (f)
40
bf-1, [F I
30
r
L_
µ -!J
I
:J
r- r
c- j
~,
,-
./
- r
---- DB with wind speed 26 m/s - JBV with wind speed 30 m/s
~
rr- ~
_ff
REB with wind speed 25 m/s
,·,
v-../- J-
I
J
I
.- -.:5
--~ ~I I
,_
I
-- -- ... -- ----- CP with wind speed 12 m/s
,_,I
,J
_,,-J
I
IJ__ r
__r
IJ-' u _/\ SNCF with wind speed 29 m/s + 1,-· .J
u
" "SNCB
~
20 180 275 375 450 525 650 800 875 100011001235135015001700190023002800 m 3800
REB DB JBV CP SNCF SNCB
Russian Railways German Railway AG Mainline Railway, Norway Portuguese State Railway French Stale Railway Belgian State Railway
RadiusR - -
Figure 4.4: Span lengths relative to track radius at European railways.
The contact wire lateral limit position under wind eper, which is dependent upon the pantograph working range, decisively influences the span length, in addition to the contact wire stagger at the supports. Pantographs with a narrow working width require shorter span lengths, Small track radii R also lead to a shortening of the maximum practicable span lengths. The relationships between stagger, wind load, tensile forces, curve radius and span lengths are considered in clauses 5.4 and 5.5. A radial force is created at the support due to the deviation in the contact wire (see clause 5.1.3.2), which, for example, should be within the range 80 N < FH < 2500 N for the DB lightweight steady arm. If a minimum radial force is not achieved the result is a loose fit and excessive wear of the steady arm linkage hook on the drop bracket. If the radial force exceeds the permitted value creating excessive bending of the contact line, this can lead to damage of the steady arm. It is possible to alter the deflection of the contact wire at the support, and to influence the contact wire radial force therefore by choice of the span lengths and the stagger. As explained in clause 4.1.3 the span length influences the elasticity in accordance with the relation (4.1). The span lengths should be adjusted correspondingly to ensure that the minimum dropper length /H min is observed on contact line equipment with reduced system heights. Figure 4.4 illustrates the span lengths of several European railway systems relative to track radii. Shorter span lengths are necessary at SNCF, SNCB, CP and JBV as a result of narrower usable pantograph widths. DB and REB can install greater span lengths as a result of the wider usable pantograph widths of respectively 1,45 and 1,4 m and thus reduce investmc\nt.
4.1.5
Selection of system height
The task of the dropper is to connect the contact. wire and catenary wire elastically. To achieve this, a minimum dropper length is needc'd. Droppers that are shorter than 0,G Ill hdum~ inflexibly esp<~cially ;,1,t, liigli sp<'<'ds. The n•gular system, he1,ght and the
' i,
4.1 Overhead contact line equipment____________
distance between the conta.ct wire and the catcnary wire at, the support should allow the installation of droppers with lengths l11 rni 11 2 0,5 m at the centre of the span, on overhead contact line equipments for speeds higher than 120 km/h. If this is not possible, shorter flexible droppers, and finally gliding dropper8, have to be employed. These transfer the contact wire lift inflexibily to the catenary wire and therefore generate force peaks in the contact force profile. The minimum lengths of flexible droppers / 11 min are dependent; upon running speed. At DB the lengths are: 'V < 120 km/h l11 mi 11 = 300 mm; 120 km/h < 'V < 250 km/h l11 min = 500 mm; 'V > 250 km/h lH min - 600 mm. Observance of the minimum dropper length is irnportant frorn the point of view of dynamic behaviour. Shorter droppers increase the probability of dropper failures, especially at higher speeds and larger contact wire lift. In the case of a catenary wire sag of 1,12 m at the centre of an 80 m span for contact lines with catenary wire BzII50 and contact wire Cu AC-100, according to (5.24), a system height of 1,62 m could be selected in conjunction with a minimum dropper length of 0,5 m. The system height should not be lower than 1,40 m for high-speed overhead contact line systems due to the influence of the system height on the contact forces (see clause 9.5.3.2). System heights in stations are usually greater than those employed on the open track. The installation of section insulators with larger system heights requires special care to avoid electrical clearance problems between crossing catenaries of different electrical sections, especially under dynamic uplift conditions.
4.1.6
Design of contact lines
1n
tunnels
In addition to the general requirements, there is a need to minimise the installation space for t'/J,nnel overhead contact line equ,'lp'ments in order to reduce the overall tunnel cross section as far as possible. As a first approximation, clue to the lack of sunshine, low ternperatures and low air movement, the continuous C'U,rrent loading u1,pacdy of overhead lines in tunnels may be taken as similar to the current loadiug capacity 011 open track [4.4], assuming the same conductors. Large movements of the catenary vvire, cuntact wire and auxiliar:v lirw feeders can oc-ctu during short-circuits, and can lead to contact with the tunnel walls. As this 1novernc1it. occurs only after the short-circuit has becu disconnect<>d [4.5], att.c)ntion need not be paid to this problem during the design of the overhead contact. li11<' The contact wzr·e heiqhl should be kept as low as possible to rcd11n· tlw tu111wl noss section and the associated construction im'<~stnwnts. I-Imvc~ver, contact wire gradients me uot penuit.ted ou high-speed tracks, so that tlw sarnc c-ont;wt. \\ ire heights prevail, as fou11d 011 the• open track. To kc\ep the tun:f!,d cross scdwn low, a low svstcrn height should IH' prm idcd \Yi thin the Ltlllll<'l; t.his n'.q11ir<)S shorL<)l' spa11 l<·11gt Its. Dcpcnclcut
4 Design ofcontact lines and cross-span equipment
upon the operating speed, alternative contact line equipments are possible, e.g. overhead contact lines with elastic supports (see clause 3.2.3.5) or overhead contact rail systems (see clause 3.4) with short support intervals, which result in lower expenditure than arrangement of contact lines on poles on the open track.
4.1. 7
Adoption of contact wire pre-sag
For some designs of overhead contact line equipments, the contact wire is not strung at a constant height above the top of rail. e.g. with design Re 200 for DB and the TGV overhead line for SNCF, the contact wire is provided with a contact wire pre-sag of, for example, 1/1000 of the span length, so that the contact wire is nearer to the track at the centre of the span than at the supports. The provision of pre-sag is based on the premise that the overhead contact line has a lower resilience at the supports than at mid span, and the pantograph therefore lifts the contact wire at the supports to a lesser degree than at mid span. In order to achieve an almost constant pantograph operating height during the passage of a train, a pre-sag is provided at mid span, which should compensate for the difference in lift at the support compared to that at mid span. The dynamic components of contact wire lift, however, increase with increasing speed and the pantograph is pressed downwards by the pre-sag at mid span. Tests [4.6] performed during the development of the overhead contact lines for the new track sections at DB showed that a pre-sag is not necessary for high-speed overhead contact line systems, and is even detrimental from the viewpoint of running characteristics. A pre-sag can definitely provide better running quality for overhead contact line systems up to 200 km/h with their relatively large elasticity differences along the line, whereby the static behaviour in the interaction between the overhead line and the pantograph is predominant.
4.1.8
Selection of dropper spacing
The catenary wire supports the contact wire via the droppers (hangers). Dependent upon the contact wire tensile force, the dropper intervals determine the contact wire sag between droppers. To limit this, the dropper intervals should be less than 12 m. The dropper intervals are also chos<,n with the objective of allowing contact between the contact wire and the track aft.er a contact wire failure, thus activating the tripping of the section feeder circuit bn)aker. This safety requirement is also satisfied even if the dropper intervals are less than doubl<' the contact wire height and the contact wire fails at mid span between th0 two droppers, since the droppers at the fault point also fail, allowing the contact \\·ire to nrnkc contact with the track, c-r<)ating a short circuit. After consideration of thes<' aspects. dropper intervals between 5 and 12 m are used. The layout of the droppers in c:01nbinaLioll with the stitch wir0s ensures a high degree of dast.icity adjacent to tlw s11pporL Fig11re 15 illustrat,(~S the dropper layout for the liigl1-spced overhead co11ta
, I \
4.1 Overhead cont.acl:_li_11_c_e_,.q~u~ip_u_1<_m_t_ _ _ _ _ _ __
143
1::-r
E co_ ~
5,0 rn
""9,17m
5,0 rn
Figure 4.5: Dropper layout for G5 m spans with design Re 330.
1=65 m
4.1.9
Use of a stitch wire
Elasticity differences exist in the contact line between the support and mi
= (Cmax
-
Cmin) /
( ernax
+ emin)
·
( 4.3)
100%
where emax and ernin represent the maximum and minimum elasticity in a span. Specifications for the degree of non-uniformity are provided in Table 9.2, dependent on the operating speed. Figures 4.6 and 4.7 illustrate the influence of the contact line parameters on the elasticity of overhead contact line systems based on the standard DB designs Re 160, Re 200, Re 250 and Re 330. The lengths and tensile forces of the stitch wires are the results of optimisation processes, whose objectives were to achieve, as far as possible, uniform elasticity near the support and at mid span. The varying elasticity behaviour for pull-off and push-off supports with design Re 200 were considered, which then le;-1.d to diffon)nt wire' lengths and tensile: forces for the stitch wires. Approximately equal elasticity values exist at the pull-off and push-off supports of designs Re 250 and H.e 330. Th<· degree of nonuniformity values for I lie four designs Re IGO, Re 200, Ifo 250 aud H<<300 ;-m' 2G %, lG %, 10 % [4.G] aucl 8 %. By comparison, tlw TGV-Atlautic- ov<·rli<)ad ('Oittact line system without stitch wit<'S shows a degree of no!l-lllliforrnit.y of 11 A (;-{: [ 1.··n 0
4.1.10
0
Selection of tensioning section length
T'lw tc\rnpcrnJ,urc) mug<' of th<' overhead contact. line <'({t1ip1tt< 11t., I.lie~ possihl<· horizontal tensil<~ fore<~ change, tit<' operating range of tlw tc·nsioniug rnedi,11iis111 n11d t 11< p<·rwit,ted tolcrnuccs for I.lie c-rn1t,wt \\"ire stnggc)r and cont ;\cl. wire' lieigltl d<'t n111i tt<' t It<' l1·11..'ium1.nq 1
1
.'i/'.r:/,um. l1·11._1;!h.
_ _ _ _ _4_D_e_s----"ig,_n_of_ contact lines and cross-span equipment
Re 160
12m
Stitch wire Bz II 25
Catenary wire Bz II 50 HCA= 10 kN
Hy= 2,0 kN
12,5
Contact wire Cu AC-100; Hew 10 kN
~-H-_ _ _ _ _ _ _ _ 80_m_ _ _ _ _ _ __
Re200 18m Stitch wire Bz II 25 2,3 kN
14m Stitch wire Bz II 25 1,7 kN
Catenary wire Bz JI 50 Dropper HcA =10 kN Bz II 10
bl
t---
cl:,
-
11,5
-
-
Hy
-
- ---~----'-4'-<,:----Contact wire Cu AC-100, Hew =10 kN
80m
Re 250 18m
18m Catenary wire Bz II 70 HcA = 15 kN Dropper / Bz 1110
E 00.
Stitch wire Bz II 35
Hy= 2,8 kN
~--1-
::::9,17 m , m
1 - - - - - - -65-0- - - - - - - - -
Contact wire CuAg AC-120 Hew= 15kN
Re 330 .
18m
18m
tf:;1
Catenary wire Bz 11120 Dropper /·/cA = 21 kN Bz 1110 /
E co_
Stitch wire Bz II 35
Hy= 3,5 kN
::::
7m 65,0m
Contact wire CuMg AC-120 Hew= 27 kN
Figure 4.6: Overhead contact. li1w system designs Re l(i() to Re 330 of Dc~utsche B;:i,hn.
4.1 Overhead
contact,
line ~.9uip111<:_~tl:_
Push-off support Pull-oft suppor1 Mid ppan 1,2 r - - - - - - - - - , - - - - - - - ~ - - = - - - - - - - - . - - - - - - ,
m~
',
1,0 1 - - - - - - - l - - - - - •,-"'----1------="'~16~
--·--r----Re 200
q O6 1 - - - - - - 1 - - - 1 - - - - - - - 1 - - - - - - - \ - - f - - - - - - - l 0
~
~
LU
---
'
~~
~100
0,4 t - - - - - - - 1 _ _ , _ - - - - - - - - 1 - - - - - - - - . , . _ + - - ~ - - - 1 ··-...." Re 330
0,3 0,2
'-------'----------'-----------'-----_J
Figure 4. 7: Elasticity profile for standard DB contact line designs.
::: 1850 in central position Catenary wire (21 kN) Contact wire (27 kN)
f".-!==
0 0
(0
: ~; ~-30°C I
I
=::J
1: -
600 ====i:==i==i:::::=1 8001---l--~~+-J 1000 l--
+25°C
2400 ~::;,..J---==J=-1=:d 2600 I--+--+--+--+--; 2800 3000
~~;::o,,+-._d-~~ ~~-L-,::,~--1~
3200 ~ ~ ~ ~ - k - i 3400 l--'~~'!,c--1'-sc-l 3600 ~--1-~"'-'~+".-i 3800 1--+--+-'.'.""'-"J~ 4000 I--+-+-"'">,-~,· 4200 l--+--+--4--'~,-'C 4400 ,_,___,_,__,_,.., +80°C ,---,--,-~ +80"C 4600 '--+--+--+---'--' 300 500 700 I 200 400 600 Distance from midpoint anchor (rn) Weight stack
...J
~
~
TR QJ
E t-0
GOf<
Figure 4.8: Operating range of the te11sio11i11g d<'vin~ for design He JJO.
146
t
4 Design of cont.act lines and cross-span equipment.
800 m 700
V
-J
.c
600 OJ C
~ C C
2
0
ro I
400
/
/
/~/
500
/,
0
iii
,
/
//
~., /
-
L = 11,8/ - 61, 1 for cantilever length LA= 3,7 m - - L 10,8/ - 60 3 for cantilever length LA= 2,5 m
300 200
I
200 265 345 446 571 715 900 111814191818m 35 40 45 50 55 60 65 70 75 80 m Track radius R - - Span length / ----
Figure 4.9: Influence of cantilever length and track radius on the tensioning section length.
The operating range of the tensioning mechanism restricts the permitted length variation L given in 5.5. The example in Figure 4.8 shows the variables that determine the operating range of a tensioning mechanism using weights. The calculation based on the installation height, the length of the weight stack, the dimensions of the arrangement and the clearance above the ground gives an operating range L = ±l,68 m. Higher tensile forces require longer weight stacks and therefore reduce the operating range. A gear ratio of 3:1 has shown itself at DB and other operators to be the optimum with regard to operating range and length of the weight stack. Gear rations between 2:1 and 5:1 are employed for installations at various railways. The greater density of cast iron lead compared to concrete reduces the dimensions of the weight stack and, therefore, reduce the installation space. This space-saving design for tensioning mechanisms is required especially in tunnels (see clause 4.1.12.3). The determination of the tensioning section length also has to consider the loss of tensile force in the contact wire, especially in curves as a result of restoring forces, in order to allow optimum passage characteristics over the whole temperature range. The tensile force loss should not exceed 8 % (see clause 5.5.2). Overall, the change in the tensile forces should be less than 11 %. Practical trials show that to maximum horizontal tensile force changes 3 % are added from the tensioning mechanism, designed as a wheel tensioning device, and 8 % as a result of movement of the cantilever in the contact line system. Figure 4.9 shows the relationship between cantilever length, track radius and tensioning section length. Length changes in the contact line induce a swivelling movement by the cantilever, which in turn causes a. displacement of the contact \Yire stagger at a right angle to the, track (see clauses :3.1 and 5.5). The swivelling movements of double cantilevers at the oYerlaps are an additional criterion for the d(~termination of tensioning section lengths. These become closer due to their opposite movement in tlt() m·(~rlaps. Tlw minimum electrical clearance between components in tlw two adjace11t nmtact lines and their support devices in insulated over-laps in accordance with cla us<' -L I .11 a re also to be considered in extreme positions.
I
( I
'
! I
4.1 Overhead contact; line equipment
__ _
147
a)
l·L ( +)
b)
1-)_ ( +)
a
a
a4
e)
b13
~--'~ a
ul
b14 a
0
a12
aH
a13
f)
(-)
b1 · 0,45
b
b1
( +) LO
b + 0,45
st
(-)
b1
b ( +)
Figure 4.10: Dcsiµ,w.; o[ overlaps
0
b1 - 0,45
Ott
b
strai1-',ht line.
a) si111-',lc-spa11 overlap with (,crtuiuatiou portal sL111dtm~s; b) t.wo-spa11 overlap uuly as 11oni11snlatinµ, overlap; c) t.wo-spau overlap; d) three-spa!! ov<~rla.p; (~) l<>m-spau m <'1 lap; f) fivespan overlap
----~-··------------
148
4.1.11
Design of connected and insulated overlaps
Overlaps with parallel contact lines, which are designed as electrically connecting or insulating transitions, are arranged between the tensioning section lengths a.nd negotiated without interruption of the energy supply and without loss of the contact quality. Insulated overlaps are called air-gap section insulations and separate the contact lines electrically. A differentiation is made between designs with one-, two-, three-, four- and five-span overlaps. Figure 4.10 shows the designs of contact line overlaps on straight track. The pantograph contacts two contact wires at the support in two- and four-span overlaps. The disturbing force-peaks that occur in this case favour the application of one-, three- and five-span overlaps, whereby the transition from one contact line section to the next occurs at the centre of the span. Contact lines for speeds up to 200 km/h use three-span overlaps. In the central span, the pantograph has contact with both contact wires over approximately one third of the span. The contact wire of the terminating contact line is raised at the supports by approximately 0,5 m compared to the negotiated contact wire. As a result, the pantograph has contact with only one contact wire at the supports. The supports of the terminating contact lines have low elasticity due to the deviation in the contact wire and the large lateral forces occurring as a result of this. Reduced span length and higher contact wire tensile force permit the contact wire to be lifted by only 0,15 m on overhead contact line equipments for speeds greater than 200 km/h. The direct linkage of the contact line to the tensioning devices increases the deflection forces at the supports, as a result of the high tensile forces, and thus reduces the elasticity further, with negative effects on the contact forces. The contact line is, therefore, led to the following poles and the contact wire is raised there by 0,5 m. This design lea.els to .five-span overlaps. The same conditions occur with all designs of overhead contact line system with small track radii and short span lengths. In these cases, five-span overlaps are employed as well Optimised m·erlaps with good interaction characteristics especially at high speeds have been developed through experimentation. It was recognised [4.8] that the contact wires should be lifted at the centre of the transition span in three-section overlaps for the contact line types Re 100 to Re 200 by between 60 rnm and 80 mm, and for five-span overlaps hv .1() mm, relative to the nominal contact wire height, so that a roof-shaped contact wire profile is formed. Then the contact line transitions are no longer noticeable on the mrasmemcnt charts for the contact forces. The contact line overlaps constitute~ critical points, especially a.t high speeds in tunnel sections. Figuw cl . 11 shows an overla.p a.rea in a t1111nr.l for a high-speed overhead contact lirw system. Overlaps that arr 11sed for dectrical insulation can he found, for example, at the boundaries of stations ( Figm<> -L 12). Closed disrnnned.ors arc\ used to shunt these during 11m111i1.I open\.tion The m<·rlaps a.r<' 01w11 dmiug uonnal dpera.tion only in stations \\'ii Ii S
4.1 Overhead contact li1w cquipmcllt
///rLJj_
149
Length of expanded area 231,0 m
'Lll'.I
U) 'Sj"
I
U) U)
U)
c:i
44,0
c:i
4'1,0
U)
t---
c:i
®
@
,_
_:;.
'1'1,0
'14,0
© -'i' T..tc!_rlin~ a~
-~4=~----1~~k4~-=======~r=rse:--=-=--=--::::--=-=-- -=--~'~===~r~~~--- -=-A 1rr-c1. ax~ =--
---l'::~'.:::S?;ee.:--::.:~:::::.,.'...--_:::--l-:::-"'_ _ _ _ _ _~u~) j___;o;,$_1-----------~f-L.J_ _..'.:::::~:::'.:'.''..__JL__ c:i
c:i
F'igure 4.11: Overlap in tunnel with expanded area. 0
open track
l--0
~(la~ overlap
station
1--0
F'igure 4.12: Overlap with disconnector.
signal is located at a distance "a" to the first pole with double cantilevers from the overlap. After the distance "a", the approaching traction unit draws less power from the overhead contact line system, so that even in an disconnected overlap, no contact wire burn-off is created b,v potential dif-fon•uccs lid,\ een the switching sections for the station and open track. The distance "a" is d<'p<•nd<'nt upon the operational use of the line (see chapter G).
4.1.12
Design of overhead contact line equip1nent and its con1ponents
4.1.12.1
Configuration of overhead contact line equipment
Ovcrlwad contact line equipments are nmtually ant.omaticall~- tensioned at both ends, as described in clause 3.2.:3.3 and illustrated in Figure 4. J:3. Tensiunin_q seci'ion lengths short.er than 750 tt1 that are crnt011ia.tically t.cnsion<'d at one end and rigidly ,rnchored ,ti. th<\ other, occur howe,er iu station areas and cit special points on the open track. Single-ended, rigidh· ;-rnchon~d tensiouing scct.iou l< 1Lgtlts offor advaut.ages especially ill tlw area of poiuts and in trnw:itiotts hd\\<'<'ll open track and a tttntwl. In these cas<'s, 11tievc1L loadillg of the m:idpoint a11.1/w1 can O(Tlll. This tnav \)(' caused by the longitt1di1Lal displacet11e11t of tltc con(a.d litt<' dtt<' to dif!<\rent a1nbient. (,<\ratures hdw<'<\ll the Ltttttl<'l and open track T\·pic,d dc~sigtt d<·tails aud <·01t1p()tte11ts have been dn·< lop<·d L
1
_______ 4_D_e_.s_,ig,,_,n_o_fcontact lines_and cross-span equipment
Length of half tensioning section
Length of half tensioning section Overlap
:c;:
,;:750 m
750 m Midpoint anchor
1
2
3
4
5
6
7
8
9
Figure 4.13: Design of a double-ended automatically terminated and single-ended fixed tensioning section. Intermediate insulation in the mid point anchor
/ Z-type anchor
ho•fwm~pdM
T , c m i o e t i o ~ Mid poiot eccho,
A,cho, fooodetio,
Figure 4.14: Midpoint with hinged tubular cantilever.
4.1.12.2
Midpoint anchors
The midpoint anchor fixes in accordance with Figure 4.13 two-ended automaticallyterminated overhead contact equipments. The midpoint anchor restricts the travel of the catenary wire and contact wire during temperature variations and after the failing of contact wire, catenary wire or contact line, Two types of midpoint designs are considered, those with a hinged tubular cantilever and those in cross spans. For cantilever designs, a midpoint anchor manufact 11n~cl from bronze or steel cor1
4.1 Overhead c:o!ltact li11e ~~[t_ti[)ItwnL
--- _ _ _ _ _ _ _ _ _ _ _ _ _ ___:::.:15::_:::l
Figure 4.15: Wheel tensioning design Re 250.
4.1.12.3
Automatic flexible tensioning
The tensionzng ·111.eclw:11:1.s·111, has th<' task of maintaining the magnitude of the tensile forces in the contact line, and therefore the position of the contact win\ as ccmstant as possible aft.er length changes in the contact wire and catenary wire as a result of temperature! vari,1tions. The efficiency, measured as the ratio of the actual to the iutcmled tcnsil<~ force, should IH' ;-1s high as possible, so that the horizontal t<,nsilc forccs Hew and He!\ do not vm_v by mon~ than 3 % [4.9]. Designs with t:e:11,,c:icm:1:n,q vw1,yh/,,, ;-u1d geo:r wheels or vuJlcy blocks.. as wdl as hydraulic or r.lcc-tro111ed1a11ical designs. cH<' e111ploy<~d as tensioning mcd1a11isrns The wheel tcnsion<'rs consist of a tensioning whee~! with two rop<' drn11ts 011 a <·ornrnon ax!<~ and n blocking d<•\ ice'. Tl1<' owrhcad contact. line cquip111c·J1t to he t<~nsioncd is att,adt<,d to lite sJtt;-dl split drnJll I,\· m<'ans of flcxihl<' st.c<~l rop<~s. \\ ltil<' the weights of th<· tensioning J11ass('S cw! 011 t It<' lmg<' drn111. The lo.t:ch-·1,n dr·,,u·r'., lock aft<'! a wirr frncltm' [H<'\'(•J1ti11g tit(' rnJtn<'t(' or cast iron m'igltts fro111 i111p,H't i11g \\'it.It t Ii<' ground stopping fmt ltn distortio11 or t It<' ('011t.;wt !in<' aud cffoidi11g t lw d;111g<~r or dropper l>1eakilg('. Tltis is t 11(' d<'< isi\<' ,l) ()JI liiglt-sp<'<'d 1>\ 1Ti1<·,1,Hill <' L<'rn,io11ing <'JtSlJl<'s 11t,1i1tt ('11;11w(' <>I pl,11111(•d t ('11sil<' 1'01 ('<'S <'Y<'Jt \\ !!<'11 difl<·ri11.~ !(·11.~t 11 ('l1iu1ges occur i11 tll<' coJl1,wt \\it!' ;11111 (·;1\(•11;11, ,,i1c•. I l1is 111<'tl1od <1lso ,tllo\\S dil!!'l!'ltl l<'nsil<' forcrs I
lI
I II'' I
1'
152
______ 4_Design of cont,1(:tli11~~s atl(l crns~:::-':'Jlcl:1:.1 equipment
Figure 4.16: Tensioning device in tunnel of new DB high-speed lines.
to be specified for the catenary and contact wires. The tensioning mechanisms for the automatic tensioning of DB's high-speed overhead contact line systems in tunnels are arranged one behind the other with a spacing of 2,5 m with matched weight stacks as shown in Figure 4"16" A combined tensioning of the contact wire and the catenary wire as shown in Figure 4.17 has the disadvantage that after rupture of the contact wire or the catenary wire alone, the vvheel tensioner does not always latch-in as a result of the articulated lever. This can result in the intact part of the contact line being tensioned with a doubled tensile force. The pulley tensioner operates 011 the J)'IJ,lley hlock principle" The weight force is transmitted to the contact line via several pulley wheels as a horizontal tensile force, as shown in Figure ,-L 18. The efficiency of th tensioning devices is approximately 97 %" Furthermore, pulley tensioners cause large distortions and adclitiona,l dropper failures after darnage to the contact line as there is no safety latch-i11 to restrict the travel after a faulL Some railway c01npa11ies usP auchor rop<)s to a.void this disadvantage (Figun~ 4"18). Tlte h:1;dro:{f,/,u; tenswner [4.10] coutrols the tensile force iu the coutact lines by means of tll(' drnt1µ,r' in volu111e of a µ,ns at1d fltticl i11 a cdinder. Tl1is <·a11ses an axial movement
adjusting ring
I
Figure 4.17: ,Jointed tensioning device with articulated lever. I
'~
,__ -Pole I
tensioning weights
I I I
i
Figure 4.18: Pulley tensioner with andtor rope. nitrogen
oil position at low temperature
(].) i
0
0. 0)1 C
"i61 c·
movement piston
-;~ontact/ino
E, 22'
position at hiuh temper.Jture
Figure 4.19: !!ydraulic t.c11c,icn1i11g d<'vicc
154
Figure 4.20: Tensioning spring (Siemens 8WL8037). a)
b}
clip
thimble crimp connector dropper wire / stranded type
bracket
contact wire dropper clip contact wire
Figure 4.21: Insulated termination.
Figure 4.22: Dropper (a) and conducting dropper (b).
of a piston, which adjusts the tensile force in the contact line as illustrated in Figure 4.19. The tensile force as required according to the specific condition of a contact line, is set by adjusting the gas pressure in the cylinder when installing the equipment. This device reacts only to changes in the ambient temperature. The electromechanical tensioning device [4.11] compensates tensile force changes resulting from temperature-dependent contact line length changes via an electrically driven spindle, whose reaction threshold can be adjusted. The electromechanical tensioning device requires an electricity supply. Only the wheel and pulley tensioners have become accepted for mainline railways. Urban transportation systems also use spring-type tensioning devices for Yery short tensioning section lengths. Tensioning springs according to Figure 4.20 are used for local area traffic installations at tensioning section lengths up to 180 n1. 4.1.12.4
Fixed terminations
Fz:i:ed terminations in contact li1tr systrrns srcme catenary wires and contact wires directly to poles. The insulation is loutt<'d at a. distance from the pole (Figure ,1.21) taking into consideration a mini11111111 C'bmm<·<~ to permit climbing the pole h_v authorised [H~rsonnd.
4.1 Overhead contact, line equipnwnt
Figure 4.23: Sliding (left) and rigid droppers with unrestricted lift (centre and right)
4.1.12.5
Dropper
The drnpper· supports the contact wire and is attached using thimbles and ,arious types of dropper clips on the catenary or stitch wire (Figure 4.22 a). The dropper is designed to conduct current as shown in Figure 4.22 b, especially in systems ·with high short-circuit currents. Consequently dropper wire ends are also terminated and bolted to the dropper clips using cable lugs. In overhead contact line sections with a ·reduced system height, where the minimum length of flexible droppers cannot be utilized. sliding droppers compensate for length variations between contact wire and catenary wire as shown in Figure 4.23. The East Japan Railway (JP East) employs stiff droppers with unrestricted lift (Figure 4.23 centre and right) to attach the contact wire to the auxiliary contact line. Examples of other designs are height-a#u,stable droppers with bolted connection clips, twin droppers for twin contact wires and lever-type droppers.
4.1.12.6
Electrical connections
Permanent and switched dcr:t:ru:al mnnections arc used in the overhead contact line systl<' darups. Switched rnnneclum.., m<' 11iad<' with the on~rhead cotLt.act. liuc <'l<'r (i
15G a)
L2 L3
L1 b)
Arcing horns
650 390 100 \''
--
\' I I /
Insulating runner
Figure 4.24: Fundamental diagram of a light weight section insulator (Siemens 8WL5545) with continuous copper by-pass runners and composite insulators (a) and with insulating runners for urban transportation systems (b).
4.1.12. 7
Electrical sectioning
Electrically insulated sections are necessary to subdivide the contact line installation into different electrical sections or circuits. Dependent upon the operating speed, section insulators are used for this purpose in stations and at speeds up to 160 km/h. On main line tracks and at speeds above 160 km/h insulated overlaps are provided in the overhead contact line. On mainlines, electrical insulation points are bridged in the basic electric circuit by a disconnector. except in situations with a substation feeder conm'ction. Passage through a section insulator with overlapping copper runner elements (Figme L24 a) does not interrupt the power supply to th<~ electric traction vehicle. Designs without overlapping copper rumwr clements as sliown in Figure 4.24 b save weight and are used ma.inl:v in urban transportation s_vsterns . Insulated runners or rods guide the pantograph along section insulators without overlapping copper runner elements where it is csseutiaJ to pn'.H:lll. 11101nentary connection of different electrical circuits. This is ;-t n:quirement in syst<'.ltlS where sections are fed from different phases or niltages and 1w1yhe a req11ircrn<·11t at tlw ends of systems to pn:Y<)tlt <·rn111e<·1.ion het,,·('<'11 two cliff<'t<'lll. rnihrn,· <'i<·<·!1 ic;il s, st<·111s. Tlw clearances
4.1 Overhead co11t.acL line <~quipHwnt
157
Figure 4.25: Light-weight section insulator with continuous copper runners (Siemens 8WL5545).
between the copper runner elements at the two ends maybe different for the ,arious ra.ilway administra.tions. They can be smaller than required between energised components for other situations. By agreement with EN 50119, the clearances at DB are 100 mm instead of 150 mm. Figure 4.25 shows a section insulator ·with overlapping runner elements.
4.1.12.8
Design of neutral sections and phase separations
Neutral sections separate neighbouring sections of contact line in such a manner that the sections are not shunted by the pantograph (s) cl uring the passage of an electric traction vehicle. Neutral sections are employed as boundaries of areas with different ener:qy supply system,.'>, e.g. bet,Yeen DC 3 kV and AC 25 kV 50 Hz or AC 15 kV 16,7 Hz, of feeder sections with cli.fferP.nt pha..ses. e.g. foeder sections in AC 25 kV networks, which are supplied from different phases of the national public power grid. This neutral section design is therefore also known as phase separation. or fr:eder sections that can have different phases, e.g. to isolate overhead contact line sections that are feel from decentralised converter stations, or continuously earthed overhead con tac I line sections e.g. under structures against energised overhead contact lin<' sections .\:<'11tral sections within
or
158
-
Neutral zone 25 kV phase 2
25 kV phase 1 a)
Overlapping section
D< L
Overlapping section
0 L
ICE
:::--::- :-
: : - ~ ,c,
~
I
Neutral zone Phase 2
Phase 1 b) O>L
Overlapping section
D
Overlapping section
L
Figure 4.26: Variants of neutral section design, (a) D L. D length of neutral section. L distance between pantographs.
TCV-Nord line (Figure 4.27) [4.12], while the AVE line \fadrid-Seville is an example of the second principle (Figure 8.6). Short neutral sections can be employed for speeds up to approximately 160 km/h. This design consists of two section insulators with an intermediate earthed section (Figure 4.28). This neutral section should be negociated ,vith the main circuit breaker switched off, whereby the length of the insulating rod prevents the pantographs shunting adjacent overhead line section. Its length is therefore to be selected in conjunction with the operating speed and the spacing between the contact strips of a pantograph. If the main circuit breaker was not switched off, the pantograph would draw an arc from the energised contact wire to the intermediate earthed section, due to the uninterrupted power flow, and trip the feeder circuit breaker. The shunting of asynchronous overhead contact line sections is, therefore, impossible in this case. Neutral sections are required as phase separations with a neutral gap, when indi,idual feeder sections are connected to different phases of the national electricity supply grid. These sections are then to be negotiated with the pantograph in contact with the contact \\·ire, but without power, with the main circuit breaker in the traction whide svvitchecl off The current does not ,UT across to the neutral section, which would cause damage to the contact line system Figure 4.27 illustrates a phase separation sectwn with a neutral zone as used on the TGV-:\Jord line in France. Neutral sections between diffel'<~ut ro:1Jway t:racf;'ion supply systems, e.g. a DC and an AC system, must be negotiated consti1tg with the pantograph lowered. Nevertheless, precautions are to be ta.ken iu cas(' a p,uitoµ,rnph is inadvertently in contact with the contact wire. On 1.lw 1\[adricl- SeYillc sn;I ('llL all anxiliarv contact line with a neutral 1
4.2 Cross-spall equjpu1ent
a)
IJ~-1
f
159
y
CD
® gJ 0 31,5 m
-~
31,5 m
361m
31,5m
1:1J-20(
-200
T +
Track axis
__L_4,50 m bis 9 m
I
L t
Track axis -
200
200
/ /
+
/
b]]EL2
b)
Insulator
~-lllllll--------T-
----1
1,8/0,55
EL1
Neutral contact line
I
I
12,00
2,00 1 40 - - - - - ~~1.2~--31-,8-~I_,4_o_3_7---1-:·--3-1,-8- ~ I -31
----It~ -------;;.><-:i
1,80/0,55
-1-----
~
r7~-~ -..n 1,8/0,55-
-111111
--
1,80/0,55
Energised contact line
----+--~I 1,40 11,40 I 1,30 ------1===-3_1-=_,8-=_-=_-_-j
-31,:i-
If-___
I ,
1
1
I
11,30
11,40
1,401
~~2- - -I- - 3 - 1 , - 8 - - - - - - -
Figure 4.27: Phase separation on the French high-speed line TGV-Nord, a) plan view, b) longitudinal profile.
and an earthed section (Figure 8.G) was, therefore, installed in parallel to the l'Ilergis(~d contact line. Neutral sections should not be installed immediately before signals. in tight rnrYes or on steep ramps, where trains starts occur or where slowly movittg traction ,ehic:les may come to a stop. If this should happen nevertheless, then the neutral section can be connected to the contact line located in the direction of trawl to enable the gapped train to pull out of the ll('utral section under its own poweL
4.2 4.2.1
Cross-span equipment Introduction
Ornss-sp11:n e1rui11·1neu!. pn>,·id<'s ,\ fixt.11r<' for the ov<\rhead coutact. lit1<· ~,11pports ,rnd thus carries ltorizrn1L,d and \('It ical !'on-<'s. Crnss-spau (\(p1iplll<'1tt. cornpris<'s all co111po11ents
,..,...,..,.,...
______
4 Dcsio11 _b__
160
---------------
or contact.
li1ws aud·-- cross-span
··--·-·--·-·-·-~-----
Figure 4.28: Short neutral section with signalling.
on one pole, between two pole or on support posts in tunnels for the suspension of overhead contact line systems. Differentiation is made between single and multiple track cantilevers, .fie1:ible head spans, portals and curve pull-offs. They are matched to the local conditions, the line speed and the requirements for the electrical and mechanical separation of the overhead contact line sections. Open track sections mostly employ single cantilevers, while one of the other designs is often used at stations.
4.2.2
Hinged cantilevers
Swivel-mounted cantilevers, which can follow the temperature induced eontact line movement are used to carry automatically tensioned contact line systems. The design of a hinged cantilever is shown in Figure 4.29. The cantilever can be divided functionally into the contact wire and catenary wire support. The contact wi:re S'U,J)J)Ort includes the registration arm the drop bracket, the steady arm with contact wire clip, the \\·indstay and the registration arm dropper or the registration arm strut. The catenary wire support comprises the cantilever tub(\ the top anchor, the contact line wire support clamp and the clictgonal tube, if am·. The cantilevers are att,adwd to the poles or soffit posts by means of insulators nnd swiv(~l brackets that permit swivelling mowments. Distinction is macle between pull-of/ snpports where the ('.Cm tact wire stagger is pulled towards the support and vush-o!f ;;11,pporls \\"IH~n\ tlw ('.Ollta('.t \Vire stagger is pushed to the side away from the suppm L. The steady u:nn is an impo1ta.nt dt\11w11t in the contact wire support. Steady arms 111a
4.2 _Cniss-spau equipment.
161
Top ancl1or
Catenary wire support clamp
/
Cantilever tube
!__ Registration arm dropper \~~:~off~u~~: ________ /----------
-·--
~--------~---- -- :::t~---1
~--~
Contact wire height
~-~
_
-~indstay
Contact wire steady arm b) Push-off support
~er::=~-= ·-~ _
Contact wire height
_
Registration arm
I ,,
--------iii
-~-~
~ - :
Drop bracket
Figure 4.29: Design of a cantilever with pull-off (a) or push-off (b) contact wire support.
b)
a)
Re istration at~~ fv/
~'kc------: FH IF
a Regist
)
,0
M
s
Figure 4.30: Forces on a pull-off registration arm, m0111
are <'mployecl to minimise point masses in tlw overhead contact line 1:200 llL Th<~ <·011tart \\'ire exerts ,\ 11101t1<~11t 1\/ = u · F\ - Ii· F 11 011 the rq!,istra1 ion m111 hing<'. wh< r<\ Fv is th<' V<'rtiral crn1t ,\d. wir<' force corn1>011<·11t aud F'i, is t Ii<' horizontal contact \Yin' !'ore<' co111potlent. II" 11 · !•\. > /1 1 • F 11 (Figm<' -l.:30a), a 111olll<'t1t. \\-itl1 dmn1wmds rntaLioll r<'s11lts at the l('!-',i~;t mt ion an 11. which is <·011tll<'rnc!.<'d In ,1 d1 op1wr. [11 th<' cas<' iu Figur<' -L30 with o · !-', < h2 · F 11 a 1110111<·11t wit Ii 11pwmd rntilt ion r<'stilts, \\ hid1 can lH' crn111t.<'rad,(~d Ollly I>\ n st111t l)('(\\('('ll tit(' r(•gi~;t1,1t.ion illltl ,rnd tlH' (',ltllii('\('t ttilH· ,is ~d1mv11 in Figu1<' 1
162
4 Desi" u
- - - --- b___
or contact lines and cross-span equipment -~---
---------
-·---
·---·-·------------
Upper swivel bracket
11-
/
Top anchor
_,='Zl======~==========:>====--c.
Cantilever tube
' Insulator Registration arri strut Registration arm
/ Steady arm /
\
/ /
\
/ /
/// Drop brac~et for large contact wire uplift
Lower swivel bracket
___CWH sz Contact wire
Figure 4.31: Cantilever with registration arm strut.
4.31. The dimension b is dependent upon the dynamic uplift for which the support is to be designed, whereby registration arm struts are often needed for uplift movement greater than 150 mm. The element between the catenary wire 8'11,pport clamp and the pole is known as a top anchor. In straight line sections and curves with large radii, the tensile force resulting from the weight of the contact line exceeds a compression load possibly resulting from deflection forces and wind influences on the wire. In these cases. a top anchor design with a rope is possible. On inner curves, the pressure force that results from the sum of the wind load and the curvature can exceed the tensile load from the contact line weight, so that a buckling resistant tubular design becomes necessary Tubular top anchors are frequently employed as standard for high-speed overhead contact line systems. This provides the same design for all cantilevers and ensures a high resistance to shortcircuits. Several railway companies employ ca.trnary wire supports which separate the functions for catenary wire suspension from the conrn'ction of the top anchor to the cantilever tube. It is then possible to modify the: s_vstem height and the stagger of the catenary ,vire at any time. The top anchor t uhe is tlw11 loarled by bending (Figure 4.32) and has to be designed accordingly. I-hngerl cantilevers can be mant1fact11rcd fro111 steel tubes with fittings fro111 1wdl<'ahle cast iron, alllminium tubes with< ,,st fit t illgs f"rnI11 i\lllrniniu111 allo\s
4.2 Cross-span eq_t1ipmm1t.
163
Top anchor
/
Catcnary wire support clamp
'
Cantilever tube
Figure 4.32: Ca.utikver with a cateua.ry wire suspension clamp movabh) on the top anchor.
Figure 4.33: Cantilever at a contact line height rcdw:tion section with auxiliary catenary wire support.
stainless steel tubes with fittings of copper or from plastic tubes or rods with fittings from copper alloy:, or cast alutt1it1ill111. The latter design is maiul_v used in urban transpnrtation with 11011tinal Yoltag<'s up to 1,G kV, where the plastic tubes take care of the insulation as ,vc:11. A nxluction of the s_vs!.<'llt height cau become necessary to lead cu!lt.act liu<'s uudct bridges. Auxiliary wires provide the suspension of the catenary wire ill tlws<' s<-ct.ious. An allxilia.ry registratioLL LttlH' as showu iu Figure '-l.33 then guid<'s Lil(' caL<•11c1n wire. The hinged cantilevers ar<) aU.adH'd to individllal poles, soffit posts 01 t111ttl<'l walls. Poles with t.,vo or a 1uaxiu111111 of three cantilevers on 01w side of i.h<' pol<' an' tH'ccssary for clesigu reasons i11 points an~as. _:\Lt<'11tio11 sltollld lw paid to tit<· opposillg ( 1avd of th<· nwtil<'vc~rs ,tttd possi hlv Lo d<'ctri< al d<'arn11u's bl'twe<)ll the· rn11t d<·\·c•r fi Lti !lgs.
1G4
4 Design of rnn1.,1c:t li11<'S and cross-span Pq11iJ)me11t
I
:;-:-- .,,.,..,._
Figure 4.34: Cantilever across two tracks.
4.2.3
Cantilevers across several tracks
If poles can be erected only on one side of a line, cantilevers reaching across several tracks offer a solution. A cross-arm attached to a pole by means of a wire anchor then supports the drop posts with cantilevers attached as shmvn in Figure 4.34. The nwltitrack cantilever does not transmit mechanical vibrations bet;ween the adjacent contact lines. It fulfils the requirements of decoupling of vibrations and increases the operational security by separating the contact line equipment of acljac<'nt tracks mechanically.
4.2.4
Head-spans
4.2.4.1
Application
Head-spans that 1wrmit the arrangement of poles in the
an'<'l adjacent to the track are
used for wiring raikay installations with more than two tracks. Spac<' between the tracks for th0. erection of individual poles is not rn~cessary .. \ restriction 011 the distance between the pole aud tire track centrdinc, as in case of linritwl nurtil<'Y<'r lengths is not necessary. \Vith !wad-spans, the indi\·id11al contact litt<' s:s,·st<~tns i11fl11c't1<"<' <'aclt otlter during the passage of pant.oµ;r,\phs and l<'ad to 1ttore t111fm011r,\lil<' n11dact h<'l1;1\·iom l\foreover, IH',\Cl-sp;\l!S do 1rot satisfy 1II(' l<'q!lir<'ltt<'Ilt !'or 1111·1//11111111I s1·,,11.rnlion of t lw main
4.2 Cros~~s1>,rn (\<111ipment
lG::i
a
. Energised upper cross-span wire / - - Head-span wire support
f=artllcd upper cross-span wire Head-span wire
Cross-span wire // dropper ·· .. ~
Lower cross-span wire
I
Contact wire support
Figure 4.35: Head-span design.
through-lines from each other and from other tracks. The\' are. therefore, employed mainly s)·stems with operating speeds lower than 200 km/h. sinc-C' the investmC'nt for head-spans is lower than for individual pole designs. 4.2.4.2
Design principles
The head-spo:n wire carries the vertical forces of the OH'rhPad cunt act line supports by means of head-span wire droppers (Figure 4.35 ). The nu111be1 of head-span \\·ires ancl their cross sections depend on the load being carried. Usualh· at least t,vo head-span ,vin~s are provided in main lin<' installations, according to [-11]. for scc-urit)· reasons. The head-span \\·ire sag fci is sp(:cified in rdation to the hC'ad-spa11 lc•ngth a in th<' ra ngc a/5 to a/10 in accordance with clause TA.3. The 'UJJper n-oss-spm1, w·iff'. carries the horizontal forces resulting from the caterwn· wire support. Ea:rt;/wd uppr.r r:rn8,'h'i/Ja:n wines are used ,vhen'HT possible•. In cutTes lateral forces from both the eatenarv wires and the contact wir<'s ca11se th(• support insulators in the head-spans to becom<' inclined. Ern:rgised upper noss-span wir<'s an' us<'d ror track radii fl < 800 Ill du<' to the otherwis<' violation of thC' 1nininu1111 clearanu)s li<'tvV<'<)ll the ea.rt hed upper st<'ad_v wire and the ('twrgised ins11lator caps. This design itl pr()\ id<'d not tHd\ in the lower, but also in the upper cross-span wire . Tlte lower rToss-s11an n1in< h<'ars th<' horizonL;-d foffcs frollt the cont act wir<'s. \\ hereby rToss-spo,n wire s1n·inys c-0111pe11sat<' fm t.<'111pcrnt1m·-d<·p<·11cl<·rtt l<·11gt lt variations in 11111 cross-span wires. A s11fficie11I ly lar.L;<' pr<·-t<·11sirn1ing <'\:<·rt<'d IJ\ t lw noss-span wire sprilli-1,S COlll!J('llS,\t('S t It<' Willd ['()!'('('S.
16G
4 Design of COlltact linr~s
a)
b)
Head-span wire
Head-span wire clamp
Upper cross-span wire
~ Head-span wire dropper Upper cross-span wire /~
~
Cross-span wire clamp
, , ., , , // ,'(,
., ,i222?2.f7222L,(.22{illr, ·,, , '/.?22272tc2221?2// d222c22 ·/ ·"V/A
·
\
Cross-span wire clamp
Figure 4.36: Head-span wire supports arranged at an earthed upper cross-span wire at centre (a) and off-centre (b).
4.2.4.3
Detailed structural design
The head-span wire supports transfer the vertical forces from the contact line equipment into the head-span wire. The cross-span wzre clarnp is attached directly to the headspan wire clamp for head-span wire supports at the centre of the head-span structure in the case of an earthed upper cross-span wire. If the support is arranged off-centre, droppers are used to connect the head-span wire clamp to the cross-span wire clamp (Figure 4.36 b). At DB and other railway operators thr following various cross-span configurations are employed: catenary wire support with a snsp<~ndecl insulator for earthed upper cross-span wire (Figure 4.37 a to c) and catenary wire support without i11s11lator for an energised upper cross-spcrn wire (Figure 4.38 a to c) with interrnl'diate insulation in the upper cross-span wire, each for earthed upper cross-span wit<' with direct attachment of the caterntr\- \dre damp at the insulator for distances up to 350 m from the midpoint anchor ( Fig1m) -LTi a), installation of a S\vinging stn, p IH)t \\ een 1he ca tenary wire damp and the insulator from 350 m to 500 m from tit<' 1uidpoint ( Figure 4.:3, b) and a guide wheel at the catewu·y \\'ir<· suppon at distauces greater thau 500 m from the midpoint (Figur<) 4.37 c). and for energised upp<)r cross-span \\·in· \\-ith installation of a ',winging strap h1•t \\-<'<'ll the cateuarv \Yire aud noss-spcHl wire up to 250 111 from th<' midp()illt (Figm<' -L38a) and a guide wheel at tlw <"atctmn \\it<' support !'or distances great er than 250 m from the midpoint anchor ( Fig11t<' -l .);--\ h) Tlt<'S<' arrnng
4.2 Crnss-span cquiprnent
167 b) ............,
a) ................./. Head-span wiro j
. . . . . . . . . . . . . . . ..
Upprn
; Head-span wire j
cross-span wire earthed
Upper
. . . . . . . . . . . . . . ..
cross-span wire earthed
Catenary wire clamp
Swinying strap ',/catenary wire clarnri //
Lower cross-span wire
c)
I
J
l ............ , ..,,,t,;",,Head-span wire """'•-«n,,
Upper
cross-span wire earthed
View"A"
A
Lower cross-span wire
Parallel groove clamp
Figure 4.37: Catenary wll"e supports with au earthed upper cross-span wire with direct, att.achment of the cat.enary wire clamp at the insulator (a), by means of a swinging strap (b) a11d with pulley
(C).
Contact wire
length into consideration. Pull-off type steady arms are used as contact wire 811.pports in a head-span for the negotiated contact wire (Figure 4.39) and steady arms above the cross-span wire for the non-negotiated contact ,virc. The upper cross-span wire serves to anchor the catenary wire at the ·m.uL110·1:11,t in a cross-span strncture as shmvn in Figure 4.38 c, adopting insulators for this pmpose. Z-type ropes bet-ween the contact wire and catenary \Yire on both sides of the midpoint prevent the migration of the contact line after breakage of the catcnarv wir<' .
4.2.5
Portal structures
Steel or aluminium strnc-tures serve as portu.Ls for mounting m'erlwad collt.,1c-t. lin<' supports and are designed as a latt.in~ beam or solid girder st.rncture (Figm<' L HJ) Due to the bending ; t!sistant design of the portals, a smaller loading is irnposcd 011 the poles and foundatio11s Lhan with iwad-spa.ns, which nrnst wit hsL\lld higlt ltorizollLc\.l loads from the
1
1
168
_________ 4 Design of contact lines a.uclf':1:2_S_s--,~pau equipment
1
a)
b)
Heedspao w,rn View"A" -c!,:
~ s s - s p a n wire energised
Upper cross-span wire energised ,
=
/
Bridle wire
/
----1:: /
Intermediate insulation
A Catenary wire
Swinging strap
Contact wire c)
p::.d-spao wi,e View"A"
Upper cross-span wire energised /
-A
Figure 4.38: Catenary wire support with energised upper cross-span wire with strap (a), with pulley (b), and with midpoint anchor (c). Cross-span wire yoke
Cross-span wire drop bracket
.I
Lower cross-span wire
/ Tube
1
Figure 4.39: Pull-off contact wire support in head-spans.
4.40: Lattice portal strndm<' with drop posts at DB. Figure
4.3 Traction pow<\r li11<'S
169
/
Figure 4.41: Pull-off pole.
Galvanised a11d coaL<\d steel lattice or hollow box profile st,r11ct mes arc predominantly used for portal structures. However, ma.iutcnauce of corrosion protection is more costly than vvith lwad-spaus. Therefore, lightweight and less maiutenauce-inteusiv<~ aluminium struc:tm<\S are employed for mass transit systems.
4.2.6
Contact line pull-offs
Pull-o.fJ:c; in contact lines locate contact wires and catenary wires laterally, without the need for supporting cantilevers Figure 4.41 illustrates a pull-off.
4.2.7
Cross-span equipment in tunnels
Cantilevc~rs in redo:n_1}'ular t'Unnels are mounted on the tunnel walls with and without recesses or on the ceilings using so.ffit posts. The supports are arranged between the tracks in mined tunnels with round cross sections. The cantilewrs are mounted singly on soffit posts as shown in Figure 4.42 pennitting the c0111plete mechanical separation of the contact lines.
Unistrnt8 are provided in the tunnels
the new DB lines to attach soffit posts and supports for the feeder lines, as well as all other equipment such as tensioning devices and switching lities. The overhead contact line planner defitws the spacing and arrangement of th<' unistruts in the tunrwls. The detailed pla.nnittg of the t11nncl ovetlwad line should therefore he completed before construction of the tuuncl starts.
4.3 4.3.1
011
'I'raction power lines Definitions
Th<' Lenn "tract.iott power lines" (TPL) it1d11d<'s fccd<'r lines. parnlld feeder lines, - hv pc1ss lines and r<·L11rn curn~ttt lines ilS di~;c11ss<'d ill cla11s<' :LI .
170
_ _ _4_D_es_·ign_ of contact lines and cross-span equipment
/ / / Catenary wire
I .~ iil - I i5 cu I t= _J
\ 300
2900
\1I
I
\ \
I I
/ ~ Vehicle I clearance gauge
/
/
/
/ / /
Contact wire
/
I I
b)
Catenary wire
E lO
U)
I
E
q
- iiltr "g? I C
i-='1
~ ~
E lO
LD
--J--
Feeder line
Figure 4.42: Supports in circular tunnels for DB's contact line Re 250; a) cross section; b) plan view.
1400
,-,---------------------
/// Five-slrano armor rod
Top of
=.,___.__,_,,___--...-- Lino post insulator
Figure 4.43: Line-post arra.ngm1l(~ll1 of TPL,
4.3 'I'rac:tiou pownr lines
a)
171
Top of Polo - -
b)
Figure 4.44: Su::;pension insulator arrangement as single susperrnion ( a) and double suspension (b).
Tip of crossarm
4.3.2
Figure 4.45: Termination of traction power line at a crossann.
Routing and supporting of traction power lines
Overhead line poles aud drop posts also carry the TPL (traction pow<'t li1t<'s). Diff<'.rentiation is made between the att,achnw11t of conductors \(J ln11· 110,c;l 1:11..,ululm·,c; (Figure -1.43) or 8'1/,,':iJWn,,swn ins·11,lu/;(rrs (Figure lA4 a all(! b). Lin<' posr i11stilators p<'rmit the TPL to be moll11ted oil the pole top without a separate l<'s l)('COllt<'S 11c•ccss,1n. \\'ll('t<·li, 1·11/de 11of!u·11.i/.,; srn/11111~ pt r1\ idr· 1ll<' I 1;i11sit io11 from 111<' 11,l< I irn1 pm1,·1 0\<'I IH•,1rl li11!' lr1 111<' r nlilc· Su,111· nn1·,/1,, !iltJlr·1: 1l1r· 1 ,11,lc• ;igainst 0
172
______:i__Design of contact. lines and cross-span ecp1ip_rne__r~~
Figure 4.46: DB's Signals El 1 (a), El 2 (b) and El 3 (c).
Figure 4.47: DB's Signal El 4 (a), El 5 (b) and El 6 (c).
undue overvoltages. The relevant standards related to electrical loading, compatibility with other cables and permitted bending radius have to be observed during the installation of the cables in cable ducts.
4.4
Signals for electric traction
Requirements arise frorn the operation of overhead installations with respect to signali8ation of de-energised, earthed and disturbed sections, of neutral sections and of unwired tracks. The significance of the signals for electrical operations is explained using DB's practice [4.14] as an example. The driver of the tra.ction vehicle recognises the necessary actions related to the signal location of signals installed alongside or above the track, called El signal. The El signals consist of square blue panels with a black and white border, mounted on one corner, a.nd displaxing white switch 8ymbol8. Figures 4.46 and 4.47 illustrate the El signals used by DB. Signal El 1 identifies the latest location at which the main circuit breaker of the electric traction vehicle has to be switched off, and signal El 2 the earliest location at which the main circuit breaker rnax be switched on. Both signals are permanently erected and illuminated at night. Th<)V are located before or after neutral sections and coupling posts. The signals at neutral sect ions ran not be ehanged and continuously show El 1 at the start of the neutral section, on the war side El 2, and at the end of the neutral section El 2, and on the rear sid< El L In case of switchable neutral sections e_ g. at coupling posts s,vitd1able signals are arranged as well. If t.he rnupling post. is dosed the signal EL 2 indicates to the driver at the IH'.giuning of H< 11tr;-1I s<~ctio11, Lha.L he should not switch off the circuit breaker. !11 cas<) of a open coupli11g post tlw signal EL 1 indicaL<'S, that, the 1wutrnl section is dfoctive and i.lH! circuit l>11·ak< 1 is to llC' opeuc
1
1
4:.~_giw.rds Lo picvcttl, rn:cid(!llLal cottt,u:t.
173
El I is arra11ged din!ctly 1111de!r El 2 for short 11e\11tral se!ctions. The driver of the traction vehicle recoguises from this signal arra11get1t<'t1L that. the~ main circuit breaker has to be swi td1ed off at the location of tltc signal aucl t.lw 111ai1t cirrnit. breaker may be switched 011 agai u after passing tlw sigual. Signals El 3 to El 5 mark overhead contact, litH! sections that may not f)(\ passed with the pantograph rn.ised. Sigua.l El 3 is lo('.ated as an annunciator signal at least 250 m before tlw following signal El 4. Signal El ,.1 is located 30 m before\ tlw track section that, is t.o be passed with lowered pantographs. Thercfon~ ti}(' pantographs must he in the lmvcnxl position at signal El 4. The pantographs may be raised again after passing signal El 5, which is located 30 m beyond the section to be passed with the pantographs in the lowered position. Signals El 3 to El 5 are not installed penwu1ently but erected during construction work and in c111ergu1cy. Signal El G is permanently installed and means "End of overhead contact line" and therefore "Stop for electric traction vel1idcs" with raised pantograph. It is located 10 m before the end of the passable overhead contact line section.
4.5
Guards to prevent accidental contact
Provisions shall be made at overhead contact line installations to protect people against dangerous voltages. Sufficient protection is achieved by adequately designed clearances or by arrangement of guards. Active parts of the overhead system such as pantographs, contact lines, cantilevers and cond He tors shall have a lateral clearance from lrnilclings of at least 2250 mrn, if only electrically f!xpert staff, electrically instructed staff and staff instructed in railway operations are present in the building, and 2750 mm, if they are accessible to the: pni>lic. If this is not possible, then guards to JJTC'lwnt acculcntial access such as lll<'Sh, steel plates or plastic panels are to be~ provided to pr<'V<'lll, nnauthorized apprnad1. Guards c;rn ,dso he 1t101111l.<\d 011 stnwtun)s such as bridge!s and footpaths, to ensure observanc<' of t!iC' 111i11i11uu11 dearann~s in accorda11ce' witlt clause 2.5. Tl1<· low<'st coutact wire !wight abme' roads nossittg railways must be at l<'ast f>,G n1. rr tit(' tle'Ce!ssan- contact wir<' height (';\!lllOt I)(' achi<'V(\d. then vrofilP. _(J(I,t('8 ,\l'('. to IH' e'n'ct<'d 011 both sides of the track in acrnrda11ce' witlt Figmc 8.2°L
4.6 4.6.1
Components and elements Overhead line disconnectors
01wrl11:I/.II !z1u: dzsr:0·11:11,111·/m·s at<)
load 1:11J1Tr11pl1Ts ,\ll(I arc 11on11,dh· 1no11tit<'d 011 pole
crnss-,11t11s. Titc'\' cousist of a fix<'d arid a 111(/\ i11g co11tact. as sltow11 in Fig11r<' 4.48. wl1icli <",Ill ')(' op<'li\Lcd (''('dtirn.lh· ()l llldllllillh In lll('clllS of ;1 lir1k,1gc . ( )u,rl1c•;1d li11c' discrn111c·ctors isolate· cit <
174
a)
b)
220 760
160 Up
to DC 3 kV
Up
to AC 25 kV
Figure 4.48: Overhead line disconnertor for DC 1,5 or 3 kV with fixed connections for load c1urentH up to 2000 A in mass transit systems (Siernens 8WLG114) (a) and overhead line diHconnectors for AC 15 and 25 kV with composite: insulators for load cmrents up to 1700 A (SicmenH 8WLG127) (b).
4.6 Compoucuts c_tnd clc11wuts
Figure 4.49: Enclosed overhead line disconnector on a bracket at the pole shaft.
under operational currents. The disconnector shown in Figure 4.48 b can be used for 15 switching cycles with nominal current. After leading these number of cycles the arcing horns should be checked and replaced in case of severe burn off. Short circuit currents cannot be interrupted by these devices. The opened overhead line disconnector provides a visible air gap with a defined insulation capacity. Designs with an earth contact are employed on loading tracks. The installation of an overhead line disc:onnector ou a bracket at the pole shaft can be used alternatively, An enclosed disconncc:tor as shown in Figure 4.49 avoids damage to conductors suspended above.
4.6.2
Insulators
4.6.2.1
Purpose and loadings
In.sulafo·1·s sqrnrate <'ll<~rgiscd components of the contact wire aud traction power lines from <~ad1 other and frn111 earth. They withstand the mechanical loading resulting from th<' enngiscd sys!.< 111 n11d shall. therdore, simultaneously satisfv both cl<'ctric-al and lll< drn.nic-,1l n~q11ir< lll< 11ts (s<·<· S<'ction 2.5.2). \·\'hil<\ i11s1tlat.ors ar<' s1tlij< ct<·d rnd_, to tensile s(,r<\ss in susp< 11
1
1
1
1
1
1
1
1
1
1
17G
4.6.2.2
Insulating materials
Porcelain, glass, cast resin and glass-fibre reinforced plastic \\·ith or without polymeric sheath are employed as 'ir1,s11,lating materfols for insulators in overhead contact line systems. Porcelain insulators consist mainly of hard pon:elain of group C 120 in accordance with EN 60 672-1, which is cornposed of china clay, felspar and aluminium. Formerly used quartz porcelain is no longer employed for high-performance insulators. The quality of the porcelain is largely dependent upon the uniform and preferably constant mineral composition and upon the manufacturing process, especially management of the firing. Porcelain is employed for long-rod insulators, for line post and for cap-and-pin insulators. Pre-stressed glass can also be employed as the insulator for cap-and-pin insulators. Alkali-lime-silicate glass is employed which, after shaping is cooled down gradually. This promotes the avoidance of undesirable internal stresses. Plastic insulators of various designs manufactured from cyclo-aliphatic epoxy resin and polyurethane cast resin (CEP and PUR) [4.15], from PTFE (Teflon) and also silicone rubber [4.13] are also employed. UV resistance and stability against climatic impacts are required of plastics for outdoor applications. Plastics allow a higher degree of shaping flexibility in comparison to glass and porcelain, which permits a high le\·el of dimensional stability and the casting of fastening elements. However, lower leakage current resistance counteracts this adrnntage. Composite insulators with glass fibre reinforced cores manufactured from cast resin and sheds made from various materials, e.g. PTFE or silicone rubber are suitable for higher voltages and high mechanical loads. While porcelain and glass insulators are brittle materials that are impact sensitive, this does not apply to plastic insulators. Composite insulators are vandalism-proof and facilitate transport and installation due to their low weight.
4.6.2.3
Designs and applications
For long-rod insulator·s manufactured from porcelain as shmn1 in Figure 4.50 a) the insulator bodies consist of glazed porcelain material, and are proYidecl with cast connection fittings at either end. Metal caps and insulator bodies are cemented with leadantimony, Portla,ncl or sulphur cement. Lead alloys are elastic, but heat sensiti,·e; Portland cement sealant is rigid and heat compatible; s 1 ilphur cement sealant is elastic, but less heat compatible. Long-rod insulators have shown themselv<:'.S to be suitable for regions \\·ith high air pollution. Cap-and-pu1, znsulcdors are manufactured either from porcelain or glass. The individual insulating caps are pro,·ided with a pinball and a cap (Figure 4.G0 b). The shape of the individual insulators can be adapted to the specific applic-atiou 1-uicl the required creepage path. The annual failure rate for cap-aud-pi11 insulators isl· 10-s and thus approximately ten-times higher thau for long-rod insulators [,LEl A u1edianical fracture of the insulator string does not occur witl1 everv fault, since th<' socket cap and pinball maintain the lll<'c-Lrnical strength of Llw darnaged insulatms. Cap-and-pin insulators
177
b)
a)
c)
Malleable cast iron cap Porcelain body
Pinball CJ)
=--~-1-----------== r---+----+----+--, ,~ ,'--------,----'----,-----'.~
lI) lI)
lD
~
Figure 4.50: Long-rod insulator with eye-cap (a); cap-and-pi11 i11sulator (b) and composite insulator (Siemens 8WL3078-2A) (c).
behave less favourably than long rods when contaminated. Their creepage path should therefore be apprnxirnately 10 % longer than with long rods. Cap-and-pin insulators are standardised in IEC 60 305. The testing of insulators for contact lines is performed in accordance with IEC 60 383. Line post insulators arc subjected to horiz:ontal bending loads. Porcelain designs with supports sho,vn in Figure 4.51 a are mainly used at DB at the top of poles for the support of traction power lines. Loop ·1.11..':iulaton-; (Figure 4.51 b and c) and insulating rods (Figure 4.51 d) with nominal streugt !is up to 75 kN are used at lower electrical voltages. Two s<'rially co1111ectc~d insulators with au intermediate neutral section as shown in Figur<' LrJ2 an~ freq11e11tlv employed in DC syst.<~11Ls. The double insulation protects staff worki11g 011 au e11<'rgis<'d system against si1t1ultancous contact with active and earL11ed compon<·11!.s. After damage, at least om' of t.h<' two insulators contiuucs to fulfil its task. 0
4.6.2.4
Electrical and mechanical rating
l1ts1il,1tu1s arc Lo I><' rated d<~cl.ricallv iu a<·rnrd,111c<~ \\"ith the conditions given in clause 2.:->:l ()/" tlics<· v,ducs. <'S[><'ciall:v tlw cr<~cpag<' pat.Its applindJ!e to the application site (T,1hl<' ·J.(;) ,111d Lit<' pmvi<' :2 ,->) <1n' 111a11d,1Lon·. Tli<' S<'l
178
a)
4 Design ofconta.ct linesaud cross-span equipment
b)
c)
0 0 0
I
20,2
12,5
20
-~--
_j t
Figure 4.51: Line post insulator with support for AC 15 kV (a). loop insulator for DC 1,0 kV (b) and DC 2,4 kV (c) and insulating rod for DC 1,5 kV with clevis and eye connection (d).
Figure 4.52: Cantilever with double insulation for local-area traffic with insulating catenary wire clamps, insulated swivel clip holder and loop insulator.
insulator technical data satisfies a.11 requirements. It is not usual to emplo:v insulation with the multiple sets as 11sed in overhead power line design for overhc ;-HI cont.act liues. I-Iowr.vm, sorne raih\·a, companies set higher individual rating factors. 1
4.6.2.5
Selection and application
Tahl<:s L3 and 1.S prmid<' ,rn m<'rvi<~\\. of sta11da.rd rnihr,n- i11s11l;-1tors f01 AC 13 k\. lGJ Hz aud in DC urlrntt t 1rn1:,plllL1t io11
4.6 Comp01w11ts and de11ients
179
Table 4.3: Porcelain insulators for main line applications. Insulator desig11
Application
Dnming
Electrical 1>ara1net.ers
Mcdianical 1mrarnet.<\rs
Eye end cap insulatm
Top. tu be• / reg1strat10I1 arm
@::
Oll)Dl)l)l)!J~ II
Creepage path -18-1 mm Rated volt.age 15 kV
Failing load 100 kN Working force up to 16 kN
Eye end cap insulator
Top tube
•1'[~
Crcepage path 760 mm Rated volt.age 25 kV
Failiug load 130 kN Working force up to 27 kN
Eye end cap insulator
Coutact line/ head-span
~&
Creepage path -18-l mm Rated volt.age 15 kV
Failiug load 100 kN \Vorkiug force up to 16 kN
Eye end cap insulator
Coutact Jim!
®1]]ffltit)t~
Creepage path 760 mm Rated voltage 25 kV
Failiug load 130 kN Working force up to 27 kN
Tube ell(l cap Cantilever tube i11sulator
~ittt1tm
Creepage path -120 mm Rated voltage 15 kV
Working bending moment up to 1,13 kNm
Tube end cap CaHtilever tube insulator
~ijij~·Dl I 'Vt .
Creepagc path 760 mm Rated voltage 25 kV
Working bending morrwnt up to 2,8 kNm
i i
•
Table 4.4: Composite insulators for main line applications. Drawiug
Mechauic:al para111eters
Insulator design
Application
Eye encl cap insulator
Coutact line/ head-span
Eye and tubf' encl eap insulator
Top t11lw
~L#~m
Creepage path 1215 mm Rated w;ltage 25 kV
MDCL 1,9 kN STL GO kN
Tube encl cap insulator
Cantil<·ver tube
~~
Creepagf' path 1215 Rated ,o!tag<' 2-5 k\
Illlll
lVIDCL 1,9 kN STL GO kN
Linc post. iusulator with flanges
Tnwt i< >Il po\\ <'I JiIH'S
~
Creepage path 12L5 Rated ,oltage 25 k\
llllll
i\IDCL 1,9 kN STL 20 kN
~
Electrical parameters Creepage path 1230 Rated rnltage 25 k \
Illlll
SIVIL 135 kN
SML Specifi<'d i\focltanical Load (IEC Gl 109) i\IDCL Maxi1nu111 D<)sign (';1ntilncr Load (JEC' Gl 952) STL Specified T<'nsile Load (IEC GI D52)
Tit<' tued1,.rnical rating rnttst allow for n1axi11111111 fon-<'s tliat n•s1dt frnttl <'x!.n•t1w loads. Tl1<' nicd1a11ind rnt.ing is hasc•d OIi tltc• 11on1imd strength. :\crnrdi11g t.o E>J :iO 11 :J t II(' 111it1it1111111 t <'11sil<' stn•11gth oft ]I(' i11sub1t rn 110!. IH' l<'ss than :J:i % of t.11(' sp<·cific•d tc•11silc• st rc•11gt li oft l1<' rnnductor s_Yst <'lits i11 \\ l1id1 it. is l!s<'d. The 111<1xi11111111 worki11g tensil<' lond 011 t lw i11s1tl,1tor shall 1101 <'X( c'ed .!() I,{ of Lite !lliuimum tc·11sil<' st.r<'11gt l1 oft lie· i11sul;1to1 1·11(' 111a:--;:i11111111 \\otki11g l)('11di11c; l<@I sll('II 110!. exceed I()(){, of (II(' n1i11i11111111 l1<•11di11g [(lad endiug lo,1d 111<1.\ ;iddit i()1r;1II, I)(' li111it<·d l1\ ;i11\ df'II<'< t io11 c ritnia d<'fi1wd i11 111(' S\ ~;te111 design
180
4 Desi_gn of contact lines and cross-span Pcp1iprnent
Table 4.5: Insulators in urban transportation systems up to DC 1,5 kV. Insulator design
Applicati<>ll
Eye encl and threaded tube cap insulator
Top tub<~
Eye encl and tube damp cap insulator
Cantil<1ver tube
Loop insulator
Contact line/ conductors
Loop insulator
Contact line/ conductors
Insulator body
Line post insulators
GRP-tube
Cantilever
GRP-rod
Cantilever
Drawing
~ ~~ 0
D
••
Electrical parameters Creepage path 130 mm Rated rnltage 1,5 k\'
M<~d1ani<:al parameters
Creepage path 130 mm Rated rnltage 1,5 k\.
Failing load 70 kN
Creepage path 130 111111 Rated rnltage 1,0 k\.
SML 70 kN
Creepage path 90 mm Rated rnltage 1,0 k\"
Sl'vIL 30 kN
Creepage path 240 mm Rated voltage 3,0 k\.
Failing load 50 kN
Creepage pa.th 2 570 nun Rated \·oltage 1,5 k\"
Dia.meter 26 mm, 38 mm, 55 mm
Creepage path 2 5 70 mm Rated voltage 1,5 k\"
Diameter 10 mm, 26 mm, 38 mm, 55 mm
Failinl:', load 40 kN
GRP Glass-fibre Reinforced Plastic
4.6.3
Clamps and connection fittings
4.6.3.1
Purpose and rating
Clamps and connection .fittings generally provide the rnechanzcal and sfr'lf,c:tural connection of components and provide electrical connections in the contact line systems and within the cross-span structures. They have to withstand both operating currents and short-circuit current loads in the energised part of the overhead contact line system. In addition to the mechanical stresses, short-circuit current loads occur in the passive part of the overhead contact line system, at rigid and fl(:xible terminations and also in cross-span equipment. The rating and selection of clamps is to be executed in accordance with EN 50 119. Anchoring da.111i)S or wire connectors shall be capabl<' of securing conductors and wires with a minimum of 2,5 tirnes the working load or with 85 % of the specified tensile strength of the-: conductors. The lower value shall he used in each case. It shall be ensured that no residual defonnatins which ca.n impair th<'ir function at 1,33 times the working load.
4.6.3.2
Materials
!vfatenals Lo h(! used fm' r:lo:111.11s arnl wn,ner:lum. jfrftru;s d<'IH'lld on thC' requirements of nmd11cLiviL\·, le.nsil<: stret1,L',tli and louµ,-(
4.6_ Componeuts aud clcrneuts
181
Table 4.6: Material properties fix clamps aud fittings [4.16]. Tensile strength N/mm 2
Electrical condudivit.y at 20°c m/(fhnm 2 )
Ek!ct.rolytc copper
200 to 300
GS
Crimped connect.or, focder damp (E-clamps and C-clamps), protective sleeves
Coppernickel wrought. alloy
290 to G40
15 to 18
Conduct.or crossing clamp, contact wire clamp, contact wire splic<\ parallel groove clamp. sliding dropper clip, dropper clip, dead-end clamp. bolts, nuts, stud bolt, double C-clamps, bridle \\·ire para.Ile! clamp, dropper strap, body for contact wire encl fitting, for section insulators and for contact wire and catenary dead-end damp, compression joint
Copper-tin alloy
440 to 590
9
Double U-clamps, bolts
Copper zink cast alloy
440 to 490
15
Contact wire clips, double contact wire clips, parallel groove clamps, stitch-wire clamps
Copper alluminiurn cast alloy
460 to 720
5 to 8
Contact. wire clips, contact wire crossing splice, sliding dropper clip, bridle wire parallel clamps, feeder clamps, concluetor clamps, dropper clips, cone-type dead-end clamps
Alluminium
115 to 130
37,7
Alluminiurn wrought alloy
215 to 320
30
Sheet metal, crimped connector, winding tape, tubes, straps, cable dog, hollow section, pin, stud, bolt, hook end fitting, swivel clip holder. dropper clip, wedge-type dead-end clamp, suspension damp, cone-type cleacl-end clamp
Alluminiurn cast allov
230 to 310
25 to 30
S\vivel clip holders, hook clips, eye clip. spade ('lid fittings, drop brackets, cat.cnary \\ ire support clamp, hook end clamp, hook end fitting, eye damp, reducing socket, cl<'vis end fitting. tongue end fit.ting, swivel lnac:k<'L S\\·ivds, dog. \\ asher, \n,dge-t.ype dead-er1
2,5
Dog, head-span wire damps, noss-span wire clamps, c:atenary wire suspension clan!;>s. crossspan d10p lnac:kct damps, d<•,Hl-<·nd clamps, hook end clamps, wedge-type
lVIatcrials
iVIalkabk cast iron, ga!V,llliSZ(!(!
~
400
Application exampks
Pin for clevis end fitting
Stainl<'ss s tc\d
500 to 700
8,3
Treaded rnds, bolts, rmts, washers
St<'<'I
3G0 t.o SJO
8.3
Tht<',Hl<'d rods, bolts, llll1S, washers, angle sect ions, flat b,1rs. hollow sect ions, nossanns, swinging st raps
'---···-·-----·------~---- -
-·
182
4 DPsigr1 of co11t.acf. lim,s a11d c:ross-spaH('.C[UiJlrnent
Copper and copper alloys fulfil the requirements of the energised parts of the overhead contact line system best.. These requirements include high mechanical strength and conductivity for damps and compression sleeves for connecting copper contact wires and copper a.nd bron:;;c catenary wires. These materials also offer long-term durability. Clamps and connection fittings for fixed and flexible dead-end devices consist either of galvanised rnalleahle cast iron, copper alurnini'/1,m alloys or aluminium cast alloys, which completely satisfy the requirements of mechanical strength and long-term durability. Table 4.6 contains electrical and mechanical properties of materials important for jointing elements. Clamps for electrical connectors and switch lines must have low resistance and long term durability. Clamps made of copper and bronze satisfy these requirements. In the case of cantilevers three product families can be distinguished: For aluminium cantilevers cast and forged aluminium clamps and connection fittings are used. For plastic cantilevers clamps and connection fittings of copper aluminium alloys are used. For steel cantilevers malleable cast iron clamps and connection fittings are used. Other combination between materials for tubes rods with materials for fittings are possible. Only under fault conditions do they conduct short-circuit currents and have to withstand these without deformation and adverse effects on their crystalline structure. Cantilevers made of aluminium are corrosion resistant, they do not require special corrosion protection and therefore have only low maintenance. Steel and malleable cast iron components require separate corrosion protection. The joining of conductors and fittings made of copper or bronze with those made of aluminium is provided for by copper-clad bi-metallic sheets to avoid electrolytic corrosion. Aluminium and copper layers are compressed together and result in a bimetal copper clad sheet. The aluminium layer is faced towards the aluminium fitting and the copper layer towards the copper or bronze fitting. In this manner, a copper aluminium bi-metal casing forms the transition from a bronze or copper catenary wire or a contact wire to a wedge type dead-end clamp made from G-Al SiTMg wa. The properties of the clamps and connection fittings can be matched to requirements by selecting the appropriate composition of the alloy. Aluminium is used for corrosion resistance, silicon for casting ability in production and magnesium for strength and thermo-annealing properties. A.luminium components combine corrosion resistance and good electrical conductivity with a favourable price, low weight and reduced cost of maintenance. Components made of copper or alurniui11111 show resistanc() against corrosion. Copper is prefered in very adverse climate awl i11 comlJiuation with glass-fibre reinforced tubes or rods. Alurnininm fittings ;-ne combined \\·ith ,tl1!11ti11i1m1 tubes. lvlalleahle rn.st irnn r:0711,71011.ents lwhm<~ !C'ss bwomablv clming short-circnits; the galvanising requires additioual coat.iug, which h;-ls lo be r<)ll<'W<~d c1t regular intervals depending upon environ mental co11di holls.
4.6_ Compou
--
183
Insulator in head span Parallel groove clamps
Stitch wire
Feeder clamp
Figure 4.53: Example for installation of fittings.
Contact wire splice
Figure 4.54: Clamps for fastening the dropper to the catenary wire and contact wire; left: bolted clamp, right: mating clamp.
4.6.3.3
Overhead contact line equipment
Figure 4.53 illustrates schematically the installation positions of damps and fittings within the overhead contact line eq'u,iprnent. Drnpper clip.s comwct tlw c-ateuary wire to the dropper and the dropper to the contact wire (Figure -!.54 lPft and right). The thim,ble with crimped coI11iector is used as conductor termination.<'. g. for drnppers, as shown in Figure 4.55 and 4.22. The contact wire splil'.c shown in Figme 4.55 guarantees the electric-al and longitudinal
Figure 4.55: (I
Tl1i1nl >le wil
Ii ni11qwrl ("(lllll('("I I II (Id"! sid<~
illljl<~lllll!CI Ill ,ISSl'ltii>i<•d (rig/ti sid<'
ll!
or l<'l"t
picl Ill I') 1l11ipp<'l. I ltillll>lc cLlld
i<'fl picllll<'). <<>Ill ;icl \\ i1 I' spii<<' ( l igltl pictlll"<').
184
Figure 4.56: Double U-clamp (left), parallel groove clamp (right).
Figure 4.57: Feeder clamp for the attachment of the electrical connection to the catenary wire (top) and for the attachment to the contact wire (bottom).
mechanical connection between two contact wires, e.g. after damage to a contact ,dre. DB and other railway operators do not permit the installation of contact ,,·ire splices for installation of new overhead contact line equipment on continuous main lines. Double U-clam,ps (Figure 4.56) connect the catenary wire mechanically and electrically with the stitch ·1.mre. Parallel groove clamps as shown in Figure 4.56 are used to co1111ect two contact wires. These can be the parallel clamped contact wire at the section insulator, contact ,,·ires and conductors, the Z-type anchor and the contact wire at the m:id11oint anchor. They can also conm'ct conductors to each other, e.g. the clamped bronze cable ar the catenary wire support in a head-span structure. Parallel grom·e clamps are unsuitable for tension loaded co11ductors or contact wire connections. Feeder clarnps as show11 in Figure 4.57 provide short circuit proof c-01111ectio11s to contact wires. They provide ekctrical connections to the catenary and the contact \\·ires. Wedge-type decul-end clo:rnps as shown in Figure -!.58 provide the mechanic-al termination of conductors and wires aud are attached to fixed or movable anchors by means of straps. Wedge-type dead-end damps arc easily installed and can be reused. Conedesign dead-end clo:mps are also used to an( hor conduc-tors and wires (Figure 4,58). They are easy to handle as wires do not nec)d to be bent.
4.6_ Componcnt,s and clements
Figure 4.58: Wedge-type dead-end clamp (left), cone-type dead-end clamp for contact wires (right). Top anchor
Eye clamp
~"'
Catenary wire suspension clamp _,.,./
Spade end fitting Insulator
Cantilever tube \
~'{'.iindsta~
CWH _'\] -
" Contact wire clip Lower swivel bracket
Figure 4.59: Components of a hinged tubular cantilever.
4.6.3.4
Hinged tubular cantilever
Figure 4.59 provides an overview on the components of a hinged t'/1,bular cantilever. Swivels as sho,vn in Figure 4.60 fix the hinged tubular cantilewr to the swivel bracket at the pole and permit the swivelling motion of the cantilever. The devis encl fi:tting as in Figm<: 4.G0 fixes the catenary win'. clam,p to the top anchor tube; a wedge-t;1;pe deadend do:mp as shown in Figure 4.58 fulfils this function with a win) rope top anchor.
Figu1·e 4.60: Swiv
4 1Jesig11 of contact lines andcro.ss-span equipment
186
Figure 4.62: Composite insulator.
Figure 4.61: Spade end fitting.
••
...
...J:·· \ .
7~· -.,;'.
-
__;j. .~ - /•
~~,;' @ J~'.1
'
'
//
\
Figure 4.63: Catenary wire support clamp, can be moved along the cantilever tube (left) and top anchor (centre), connection of the cantilever tube with the top tube (right).
The spade end .fitting as shown in Figure 4.61 connects the top anchor tube to the insnlator eye cap. The insulator with eye cap and tube cap (Figure 4.62) connects the cantilever tube directly to the swivel hinge. Catenary Wffe support clamps support the catenary wire at the hinged tubular cantilever. They allm-Y the catenary wire to align parallel to the track axis irrespective of the cantilPver position. They ;-1lso often connr.ct the cantilever tube and the top anchors in cantilevers. Catenary wire support clamps can be shifted along the cantile,·er tube (Figure ~!.63 a) or top anchor tube (Figur0 -1.63 h), cir.pending upon the design. Figure 4.63 c shows a catenary ·wire support clamp. which can be shifted along the top anchor tube and supports the catenary wire onlv. The cat(".nary wire and contact \\·ire are often insulated from the cantilever in urban transportation systr.ms. Catenary wire support damps with cast resin bodies of this design support the catenary wire. An 1.11.s11.ln!:r:d steady a:rm provides the insulation of the contact wire. The hook encl .fitting (Figure 4.G4) contH'<·ts ill<' n'gistration ,um to the cantile,·er tube by means of an eye clamp, which is dcsigtl('d ror con11ectio11 to various tube diameters. The registration arm is supported hv ,\ 11·111..'ilrnJ-ion arm. rlroppr:,, which is attached to tlte tegistration nnn by tll<'att:, of.-\ /11w/, r/111 (Figtm' -LG,"i C<'ItLr<') .-wd a dropper cla111p 011 tit<' stitch wire 01 I)\ ,\ IH>ok 011 1IH' <;1t<'lti\l\. wir<' clarnp Th<' eye rl1p (Figure
I Pi 7
Figure 4.64: E,<' da111p wit.Ii hook <~IHI fit.ting 011 t ]I(' rnnlil<~vcr tulH'.
Figure 4.65: Ey<' cla1np (ldt ). hook dip (c<~llt.rc), a.11(1 drnp lnadH't ( l<'f't sid<' ul right pict.1m~) with lightweight stmdy anu (right. side of right. picture).
Figure 4.66: Ligl1l\l'<'igli1 sl<·;1d1 ;11111 (1<·11)
,lll(I
<0111;)('1 11i1c·
,c!,l
sl11d (1igltt.).
188
-
_,,.,,'
___________________.,_,_____of_ cont,_11~,~--~nes and cross-span equipment
/ Figure 4.68: Line hanger for contact wire in curves.
Figure 4.67: Glass fire reinforced plastic cantilever across two tracks in urban transportation systems. Pole
Pole
Swing ng strp Catenary wire pulley suspension Cross-span wire clam Cross-span tensioning spring s an wire Cross-span eye clamp
Cross-span drop bracket
Cross-span wire yoke
I
Cross-span Steady arm eye clamp
Figure 4.69: Important clamps and connection fittings in flexible head span structure.
4.65 left) attached to the registration arm supports the winclstay_ The contact wire steady arm is attached to the drop bracket (Figure 4.65), which is designed for various tube diameters _ Steel tubes are used as steady arms at speeds up to 100 km/h, and aluminium profiles for speeds above 100 km/h, as shown in Figure c!.66. The contact wire dip (Figure 4.67), which is attached using a C-pin on the grooved stud, is used to guide the contact wire at the steady arm. Figure --L67 shows a glass fibre reinforced plastic contilever that has been tailored to suit the requirements of urban transportation systems.
4.6.3.5
Head span structure
Figure 4.69 illustrates schematically the installation positions of important clamps and connection fittings in a head span. The head span wi're clamp shown in Figure 4.70 attaches the support to the head span wire. The cross-spar,, win· clarn.p as shown in Figure '1.70 co11nects the cross-span wires with the contact line supports Tlw cu11rn'ction upwards is the ll('ad span wire clamp. The
4.6 _9ompouents
nn_d d(\lllents "
189 ·-----·· ------.::......
Figure 4.70: Head-span wire clamp (left), cross-span wire clamp (right).
Figure 4. 71: Catenary wire support clamp (left), swinging
strap (right). catenary wfre s'IJ.spension clamp (Figure 4. 71) c,uTtcs the catenary wire m head span structures directly or by means of a dropper. Swinging straps (Figure 4.71) provide the connection lwtween the cross-span wire damp or insulator and the catenary wire damp for caten,i.r_v wire snpports in a clist,u1c(' range from 350 to 500 rn from the midpoint anchor in the cmtt,act line t,<)11sio11i11g section. The catenary wire pulley s'IJ.spension provides mohil<' snpport for the catc11ar_v wire (Figure 4.72 left) at the support in the upper cross-spat1 wire for supports thc\t arc located 11101c that1 500 m from the midpoiut anchor of the rn11tact liue section. Cmss-sJJll'il, eye clamps (Figure 4. 72 right) ,U-<' 11s<'d for th<' attac:l,mcnt of the steady ann to th<' lower cross-spau wire. Oross-SJJ(l:/1, teuswnhu; Sfff'l:/1,gs a::; shown iu Figure 4. 7:3 co111pe11sat<' for length changes in the cross-span wir<'s in cross-span strnctmcs and shoHld alwa,\'S be provided as a geucral ml<' . Two parnllcl crnss-spau tc11siotti11g springs ,tt<' used for cross-spau \rin' tensile forr<'s gr<',\l<'l t lta11 G kN
190
-~
4 Design of contact. lines and cross-span equipment
Figure 4. 72: Catenary wire pulley suspension (left) and cross-span eye clamp for the attachment of the steady arm to the lower cross-span wire (right).
Figure 4. 73: Cross-span tensioning spring.
4.7
Systemisation of the overhead contact lines and their components
The components of the overhead contact line system fulfil various functions. The classification of system components with the same functions into groups result in a functional grnup structnr-e. It serves as a means for the complete survey of the overhead contact line system and for the computational 1m1.tcrial selection during planning of implementation. Further sub-groups grow from the forn1atio11 of main functional groups as shown in Figure 4.74. The basic principle of the subdivision forms, as far as possible, the f-iow of mechanical loadings from the ov<~rlu~a.d c·ontact lin<\ equipment ov<~r the cross-span components and the pole to the fou11clM.iotL The overhead cor1,tact frne 1:11,.c;tallatwn ca11 lw classified into sewn main functional grnups that consist of sen~ral snb-fu1tction groups (Figure 4.74). Ir 01w assigns the overh<'ad t onta('(, lin<' i11sLdlatio11 to the high<'st level and the main f't111('Lional groups to the' S<'
4. 7 Systernisa.tion _of the overlieadco11ta.ct lir1~~ ~~II(~ tJ1~i~_com poneuts
191
Overhead contact line installation 1
'
Foundations
'
'
I Supporting structures
11
Cross-span equipment 13
12
contact I Overhead line equipment 14
t
t
Traction power line 15
I andOisconnectors accessories 16
t
Earthing, return circuit, special fittings, plates 17
Figure 4. 7 4: Main functional groups in the overhead contact line installation. Overhead contact line installation 1
' '
Foundations 11
Single cantilever 131
Support structures 12
t
Cross-span equipment 13
Multiple track cantilever 132
Head-span structure 133
Overhead contact line installation 1
t
'
Overhead Others conlact line (see 14 Figure 4 71)
'
t
Portal
Pull-off
134
135
i
Cross-span equipment 13
' ' '
Functional group 131 single cantilever Module 001
Catenary wire support 1311
'
Contact wire Fixing supports of registration cantilever at pole 1313 1312
Module 002
Module 003
Top lube 13111
t
Cantilever tube 13112
'
Diagonal tube 13113
Catenary wire support clamp 13114
Figure 4. 75: Extract from t.wo-climensional functional group structure.
Functional group 132 multiple track cantilever
Module 001 multiple track cantilever Design A Module 002 multiple track cantilever Design B Module 003 multiple track cantilever Design C
Module004 Single cantilever Re 250, R>3000 m, MVK<3 4 m, pull-off
Figure 4. 76: Functional group structure with functional modules.
as shown in Figure 4. 75, as an extract from the overall structure. Functional modules are contained in the functional groups, which arc [ontH)d in accordance with the respective overhead contact line system design . :\ thn'<'-dime11sio11al structure (Figure 4.76) is created from the tvvo-climensional strncturc by lhe formation of functional modules for clifforcnt overhead contact line designs . Dependent upon the application, the required functions arc assigll<'d to tlw fu:11,ctum,al nwdule8. It is therefore possibl<~ to assign a complete cantilever to 1.h<' third level, as shown in Figure 4.75, a11d to select it in this level. The catcwuy wire support, t.he contact wire support and the fastening fittings of the individual c;-rnl.i le\ ()LS belong to the fourth level. The fifth levd contains the functional group's top ,rncltm, rn.ntilcver tube, diagonal tube and catcuary wire support damp for the catcnat,\ \\·irC' support. Tlw sumllest unit i11 t.h<) fu11ctional module is fornwcl by all dc!ll('tll.. s1wh ;1s ;1 bolt, nut. or split pin. Th<' <'l<~nwttl s an• grouped into !'1111< tirn1al 111od11l<'s .. \ lt11wt io11;d tttodule
192
Figure 4. 77: Tensioning equipment for the contact wire on the T\mis tram system, weights arranged inside the pole.
can equally consist of sub-functional modules and elements. The possibility therefore exists to define any type of design using this functional modular group structure. It forms the basis for computer based material selection during planning. Material logistics at the construction site and condition related maintenance can be based on this structure as well.
4.8 4.8.1
Implemented contact line systems Mass transit systems
Light rail system Tunis. The railway system operated by Societe du Metro Leger de Tunis (SMLT) vvith DC 750 V stretches over 76 km comprising four lines on dedicated tracks. The main tracks on open stretches and in the metropolitan area are equipped with a cate1rnry type overhead contact line. The catenary wire CuAg 95 is fixed-tensioned; the contact wire CuAg AC-120 is weight tensioned at 12 k\1 [ ,1. 1 7]. The standard contact wire stagger is ±0,20 m at the supports. Tension wheels are used as the tensioning device, the tensioning weights run inside the poles (Figure -L 77). Galvanised steel tube cantilevers provide a system height of 1,60 m and a standard contact wire height of :\7E5 m. The cantilevers han'. insulators between the contact wire and the stead,· arn1s, catenary wire and top pole bracket on one side, and between the top pole bracket ;-rnd pole on the other, thus providing double insulation. A loop insulator prmides insulation in the top tie anchor (4.8.1).The spans have a maximum length of 60 nL TlH' tensioning s<:ction lengths of the overh<~ad are limited to 1200 m and those oft li0, trnllc',. wire equipment with single trolley wire to 1000 m. A simple trollr:y 11111 e rnntatt line without ;-) catenar_\· win: supplies the vehicles with power in the clepot are.a (Fi12,1m' '"1.79) .
4.8. lz1tpl<\rne11(«>cl
cottLi1c( li1w sysL<\IllS
·st
193
· ~· ......:
-
Figure 4. 78: Pole with pull-off and push-off support and double insulation system.
Figure
011
4. 79:
ov<'rl1<'nd
<
1111ill.ipl<· t.1
;l('k
Tunis tram
Troll<\Y
rn1Lict
lin<)
wire 011
<·;1.11Lilev('rs iu
T111tis i\il;i1 i11<' d<'pot.
194
4 Design of contact lines and cross-span equipment
Figure 4.80: Pole with a tensioning device
Figure 4.81: Pole and foundation on light
on an open line section on light rail in Portland.
rail in Portland.
Overhead contact line for the light-rail TRI-Met in Portland, USA To connect the airport and the Hillsboro suburban area by rail to the Portland central light-rail system two extensions with 29 km and 8,8 km, respectively, were installed as part of the 53 km network. The light-rail contact line \\:as used and is operated by DC 750 V. This contact line design takes care of the specific climatic conditions with a temperature range from -30°C up to 50°C. The extension to the Hillsboro suburban area is equipped with a vertical contact line equipment having a contact wire Cu AC152 mm 2 (300 MCM) tensioned by 15 kN together with a catenary wire with 162 mm 2 cross section (250 MCM) tensioned by 15 kN at 60°C (Figure 4.80). The extension to the airport is equipped with a horizontal catenary. The maximum span length is 64 m, H-beam steel or steel tube poles are used (Figure 4.81). Overhead contact line for the light-rail system Bursa, Turkey In the city Bursa a new 80 km long light-rail system has been erected including a depot. According to the local and climatical conditions the overhead contact line was selected for the line operated by DC 1,5 kV. The ambient temperature range is between -40°C and +45°C. The contact line is adjusted to the running speed of 70 km/h and consists of a contact wire CuAg AC-120 and two catenary wires Cu 150 connected by current resistant droppers made of BzII25 (Figure 4.82). Glass fibre reinforced plastic (GFP) cantilevers are used. In the tunnel sections elastic supports are adopted to support the contact line. In the depot area a trolley wire contact line with bridle suspension has been installed. The poles are made of hot-dip galvanized H-beam steel sections set on in-situ cast concrete foundations. The maximum span length is 64 m, the maximum length of a tensioning section 1500 m. New tramway in Oberhausen. 8tadtwerke Oberhausen AG (STOAG) [4.18] recommenced tramway operations on the line between Sterkrade and Landwehr in 1996, after an interruption of 28 years. The 8 km long line provides a connection between the town centre and residential areas. lt runs partly on dedicated track. The tramway achieves maximum speeds of 70 km/Ii and is op<\rn.ted with DC 750 V.
,.J..8 Implemeuted contact line systems
Figure 4.82: Pole and cantilever on north line on lightrail-system in Bursa.
195
Figure 4.83: Glass fibre reinforced plastic cantilevers in Oberhausen.
One or two catenary wires are employed, each consisting of 150 mm 2 Cu-conductors, corresponding to the current loading in the respective line section, and a contact wire CuAg AC-120, each tensioned with 10 kN. Current resistant droppers Cu 25 mm 2 connect the catenary and contact wires. Glass fibre reinforced plastic cantilevers (Figure 4.83) support the contact line. Tensioning equipment is used to tension the catenary and contact wires separately. The tensioning weightsfakes are not directly visible; since they run inside the poles or in underground cavities (Figure 4.8,:1). Hong Kong metro system. The !Vlass Transit Railway (MTRC) is a modern metro system and forms the transport backbone in metropolitan Hong Kong. MTRC operates a network consisting of several lines supplied by DC 1500 V. The lines nm mainly in tunnels. A catenary wire could not be installed on the K wun-Tong line clue to low ceiling heights in rectangular and round tunnels. Elastic supports carry t;wo contact wires CuAg AC-120 (Figure 4.85), which are weight-tensioned at 24 k:'\. Four parallel feeder lines each with Cu 150 provide current in the tunnel in addition to the contact wires. Hing
!I \1ii \i, ~
_ _ _ _ _ _ ____:4~D__::e:.::._si,gn o~~.ct lines and cross-span equipment_
196
Figure 4.84: Tensioning device with tensioning weights running in a cavity.
--~~
-------
----------------
I
'
i \\ 300mm
Figure 4.85: Elastic tunnel Pan1agrapt1
support.
"-"""""
________
"
__________
197
__:::::.:_
Figure 4.86: Cantilever for double contact wire in tunnel at Lai King station on MTRC.
Figure 4.87: Overlap of tunnel overhead contact line on MTRC in Hong Kong. with the contact line. Figure 4.87 illustrates the contact line overlaps, each consist of two catenary wires and two contact wires.
Conductor rail installation for the Bangkok Mass Transit System (BTS), Thailand In the city of Bangkok, having more than nine million inhabitants, the installation of approximately 200 km of city mass transport lines is planned to improve the infrastructure during the next 20 years. A 23 km loug section, called the Green Line, has been commissioned, vvhich is equipped with a third rail and operated by DC 750 V [4.19]. The conductor rail installation adopts aluminium steel composite rails of the type 40 70G (Figure 4.88) and conducted at the bottom face. The conductor rail is equipped with a weather resistant plastic cover. The application of disconnect.ors along the line ,vas waived with exception of the depot supply, thus achieving a clear line co11ncction. Duri11g standard operation all feeding sections of the conductor rail are rn111tccu~d via the DC 7G0 V sub-stations. I11 cas<' of failure of one sub-station the adjaci1tg feeding sections can b<' coupled by nwans of a ciICuit break<)r per track. The use of cirCllit breakers results in a higher fiexil>ilit:v all([ selectivity during operation and ;-woids cost-effective i11terloc-king of discon11cctors. In order to lwep Uw stray currents at, a low lcYl<' l<'vd th<' rails wen~ w<-ld<'d iu t.h<· lrn1git11dinal directioll and the individual
4 Design of contact lines and cross-span equipment
198
Figure 4.88: Station with conductor rail used in BTS Bangkok. Parallel feeder line AAC 240 ______.,._----,;~.,;:::
E 0
Catenarywire Bzll 70 mm 2 HcA=15kN Earth wire AAC 240
a:,_
Stitch wire Bzll 35 mm 2 Hy
~
= 3,5 kN
- ' - - - - - - l - l . _ - ' - - - - 1 - - ~ - - - L - - - " . - - - - 1 . . . - ~ 1 --
E
9,0 m
65,0 m
-'-,-m-'--l--- Two contact wires CuAg AC-120 18 0 Hew = 2 · 12 kN Dropper Bzll 16 mm2
0
(')
LO II I
TR
~
0,30m
0,30m
Track centre line
-~-
-1Contact wires
Figure 4.89: Layout of the overhead contact line for the DC sections Madrid-Atocha and Seville-St.Justa.
rails and the tracks were bonded by copper conductors correlated to the requirements of the track release system. Within the stations remote controlled short-circuiters with a relay in closed circuit reset arrangement are installed which connect the running rails to the structural earth when the permissible touch voltage of the rails is exceedPd.
4.8.2
Main line systems
4.8.2.1
Overhead lines for DC 3 kV
DC 3 kV sections on high-speed line Madrid-Seville. The Spanish government decided to build the hi,qh-speed l'/.ne Madrid-Seville with standard-gauge tracks and AC 25 kV 50 Hz single-phase pmvcr supplies. This required the conversion of the widegauge track and the installation of a new DC overhead contact line for the encl sections to the stations Ivfadrid Atudta and .S<'.,·ill<~ St. Justa. The new DC overhead line system
4 .8 Im plemenLE,cl~ontact line systems ______________________________ _
199
Figure 4.90: Partial view of a portal with DC overhead contact line before Atocha station.
Figure 4.91: Contact line support 011 the Moscow--St. Petersburg line, to the left before the reconstruction (Photograph: Matzner) and to the right after the reconstruction.
needed to cope with both high currents and speed, with two pantographs raised on the AVE traction units. The layout of the contact line system [4.20] as shmvn in Figure 4.89 is derived from the design provided in the AC 25 kV sections. The maximum span length of 65 m guarantees optimum running characteristics. Two contact wires, each tensioned to 12 kN; one catenary wire, Bz II 70, and a parallel feeder, 240-ALl, provide the necessary current capacity. Alumznzmn l/:inged cantilevers support the overhead contact line on open track. Steel portals support the contact lines in stations using drop posts, as shown in Figure 4.90. DC 3 kV overhead contact line for the Moscow-St. Petersburg line. The October Railway (OEB) operates the line between Moscow and 81. Pf'./crslm:1:q at DC J kV for S!H:!<)ds lip to 200 krn/h. This line is one of the most used trncks in Russia. The layout of the cantil<'.Y<'r prior to th<' rern11struction can lie seen in Figure 4.91. A suspension insulator at.t.aclws the cate11ary wire to the cantilever, which consists of c\ll).!,l<' sect.ions Two s!<),1<1\-arrns µ,uide th<'. <·011tad, wires witl1 a sp,1cinµ, of -10 mm.
200
_ _ _ _ _4_D_es----"ig~(:)_f contact lines and cr~)ss-span equipment
Figure 4.92: Portal structure on the Moscow-St. Petersburg line near Tor:(janoje (Photograph: Matzner).
· Catenary wire CuCd 160 HcA = 27,5 kN
=..L---~-- Two contact wires CuAg AC-150 E co_
Contact wire pre-sag 60
lD "1"
II
I
TR
60,0m
Hew= 2 · 15 kN
m
J
,~--------------~
6
0,20 m
Track centre line
I-
~
-
0,20 rn
-
Contact wire
Figure 4.93: Layout of DC 3 kV overhead contact line for the Direttissima Rome-Florence in the southern section.
The overhead contact line was upgraded for speeds up to 2.50 km/hj Figure 4.91 shows a support of the two contact line sections installed by Siemens as an alternative for reconstruction. This sect.ion has proved its quality during operation. The cantilevers are mounted predominantly on concrete poles on open track, which also support telephone and signalling wires. Pulley-wheel tensioners compensate for temperature induced wire length changes to both cat.enary and contact wires. The insulators used are adequate for AC 2,5 kV operation as well. OEB also uses portal structures in addition to flexible head-span equipment in station areas. Concrete poles support the lattice portal as shown in Figure 4.92. The lower cross-span wire fixes the contact ,vire supports on the portals. Direttissima Rome-Florence. The 2;33 km high-speed line operated by the Italian 8tate R.ailway (FS) c-ornpld.ed i11 19~)1. th<' Direttissirna Rorn<~-Flou~nce, is operated
4.8 In1E~elllellLed coutact _liue systems - --~
201
Figure 4.94: Tensioning devices on the southern section of the Direttissima near Orvieto (Photograph: Puschmann,
Bjorn).
at DC 3 kV and a speed of 250 km/h [4.21]. On the southern section of the line, the contact line system consists of one catenary wire and two contact wires. Stitch wires are not present in this design. The catenary wire is tensioned at 27,5 kN and each of the contact wires at 15 kN (Figure 4.93). Pulley-wheel tensioners with two pulleys compensate for temperature induced wire length changes to both catenary and contact wires in this section (Figure 4. 94). The contact line system on the northern part of the track consists of two copper contact wires Cu AC-150 each tensioned at 15 kN and two 160 mm 2 cadmium-copper catenary wires each tensioned at 15 kN. Two stitch wires at the supports ensure more uniform elasticity along the span. Tensioning equipment is used to tension the catenary and contact wires separately. Three span overlaps provide contact line changeovers. Portal str-uctures support tensioning devices above the contact line. Pulleys guide the wires out of the portal. Hinged tubular cantilevers support the contact line. Steel wire ropes are usually adopted as top ties. Drop posts made of galvanised lattice steel mounted on the portals support the cantilevers. Portals are predominantly employed (Figure 4.95). A hinged joint is used to attach the portal to the foundation (Figure 4.96). This transmits only vertical and horizontal forces to the foundation but no moments. DC 1,5 kV network at SNCF in France. The French State Railway (SNCF) operates (status J'viarch 1999) a 5833 km track network at DC 1,5 kV. Compouricl contact lfr1,e eq·uipment, ·which consists of a catenary ·wire, auxiliary catenary wire and two contact wires, as shown in Figure 4.97 a, predominates on main lines. Stitch wires arc not employed. Secondary lines are equipped with a simple or \·ery light catcnary system as shown in Figure 4.97 b. The span lengths are 63 rn on straight track. Pl!lley-wheel tensioners with a gear ratio of 1:5 are mainly used. Single I-I-beam steel poles carry tile contact and catenary wire supports.
202
4 Design of contact lines and cross-span equipment
Figure 4.95: Portal with cantilever and drop posts on the Direttissima Rome-Florence near Valdarno in the northern section (Photograph: Puschmann, Bjorn).
4.8.2.2
Figure 4.96: DC 3 kV line RomeFlorence,· attachment of the portal to the foundation (Photograph: Puschmann, Bjorn)
Overhead contact lines for AC 15 kV 16,7 Hz
Overhead contact line designs Re 100, Re 200 and Re 330 at DB. Design DB Re 100 is employed for speeds up to 100 km/h [4.22] (Figure 4.98), it consists of a catenary wire Bz 50 and a contact wire Cu AC-100, each tensioned at 10 kN. Stitch wires are not employed at this operational speed. The system height is 1,4 m at single supports and 1,8 m in flexible head-span constructions. DB employs design DB Re 200 (Figure :!.99) for speeds up to 200 km/h, with a stitch wire tensioned to suit the support. Catenary wires Bz 50, contact wires Cu AC-100, stitch wires Bz 25 and droppers Bz 10 form the contact line system. An 18 m stitch wire at a pull-off support allows almost the same elasticity to be achieved as with a push-off support with a 14 m stitch ,virc. The degree of non-11,m,formity of elasticity is 16 %. The design DB Re 330 (Figure 4.100) [4.23] permits speeds up to 350 km/h. Employing a catenary wire Bz 120, with 21 kN tensile force and contact wires CuMg AC-120, with 27 kN tensile force, reduces the degree of non-uniformity of elasticity to 8 %. The 18 m Bz 35 stitch wires with 3,G kN pretension, ensures a low variation of elasticity. Separate tensioning devices compensate for length variations in the contact wire and the catenary wire. Low maintenance alumin'iun1. hinged cu.nt'ileve1·s support the overhead contact lines (Figure 4.101). Concrete poles are prd<'tT(~d for single supports.
203 ---------------------------------------=--=-
a) Catenary wire Bz 116,2
E lD 0
Bz 104 or Bz 143 Twin contact wires Cu AC-107 or Cu AC-150
LC?. -r'-r-r'.-r'-T--,--'-r-.--'--r--r'-T--,--'-r-r'.-r'-,-----r-'-c,----,---Lr-r½---r-'-,.-,--'c.,-,r'-,------r'--,-,---,-,-,-,.,.-r.- Auxiliary catenary wire ~~~.__,__,__--'-+--~~~~~~~~~~~~~~~~~~.._,_~~~
I
5
TR
0
b) Catenary wire Bz 65,4 or Bz 116,2
E lD 0 (')_
63,0m
E lD
r----_ lD
II
I
TR
5
0
o,~ml
f-----
T r ; centre
•
~---------------i,,='7{f=-o-·~ Contact wires
m
•
Figure 4.97: Layout of the SNCF DC 1,5 kV overhead contact line system, a) normal or reinforced overhead lines for main lines and b) very light and normal overhead cont.act line for secondary lines.
E
Catenary wire Bz II 50 HcA = 10 kN
0
-st_
__ _
--'-----+-~--'--------'----"----''----'-----'-----'--+----+---
E 0
__________________,___, 80,0m
Contact wire Cu AC- 100 Hcw
5,0m
LD_
U}
I
TR
s
o
Figure 4.98: Layout of DB overlwad coutact. liue design Re 100.
10 kN
204 18 m
E co_
Catenary wire 87 II 50 HcA
0
Contact wire Cu AC-100 Hew
10 kN
10 kN
E 0 lD
lf)
80m
II I
TR
~ 0,40 m
Track centre line
0,40m
-~
Contact wire
Figure 4.99: Layout of DB overhead contact line design Re 200. = 21 = 3,5 kN
Catenary wire Bzll 120 HcA
E 0
Stitch wire Bzll 35 Hy
cq 1---+--
~----+----+-~-----<--~-~-~~-~..,,....,~--18, m 65,0m
E
kN
Dropper Bzll 16 Contact wire CuMg AC-120 Hew = 27 kN
0 (')_
lD
II I
TR
s U
Track centre line O,~
-~ -
~ Contact wire
I ~
Figure 4.100: Layout of DB overhead contact line design Re 330.
Portals are necessary for the wiring of long turnouts and crossovers with large radii and transition speeds up to 200 km/h. They allow for the mechanical separation of the contact lines and carry cantilevers in crossover areas. Simulations and tests have validated the superior dynamic properties of this design of overhead contact line. Design Re 330 was first employed on the new Berlin-Hanover high-speed line [4.24]. Standard ov_~rhead contact line at OBB. The Austrian Federal Railway (OBB) renewed the Otztal-Haiming section on the Innsbruc:k-Bluclenz line in 1994. A low maintenance design was achieved using rectangular concrete poles and aluminium cantilevers. The contact line consists of a 70 mm 2 copper catenary wire and an Cu AC-120 contact wire. OBB implemented the contact line mainly as half tension lengths. These are tension lengths \,·ith a maximum l<)ngth of 750 m and are equipped \\·ith fixed anchors on one end and weight tensioning ou the otl1er. T!te bwont of th<' standard contact line
4.8 Implemellt,ed contact, lj11e ~systems
- - - - 205
Figure 4.101: Pole with cantilever and tensioning device for contact line Re 330.
E 0 t.D
Catenary wire Cu 70 HcA= 10,8 kN Stitch wire Bzll 35 Hy = 2,8 kN Contact wire Cu AC-120 /-few= 15,3 kN
E 0
65m
(')_
tD
TR 'v
;!
;I
~-tre_l~-e-=----===:::--=t=~tf---= o
Co,tacl wi,e
o
Figure 4 .. 102: Layout of OBB standard overhead contact line for new lines.
s_ystew is illustrated in Figure 4.102. Th() parallel foecler line, consisting of ACSR 260/23, is supported on line post insulators at. the pol() top (4.103). ()BB uses a fiexible head-span design for supporting the contact line in stalions. Enen;'i.'ied uppe·r cToss-s7Jo:n win:s and catenar_y wire supports with dropp<'tc, arC' u1aittly usc~d. The cross-span win~s are attached to the rectangular concrete pol<'s usi ttg springs . Sing!<) cantilevers for platform areas are shmvn in Figure 4.104. Overhead contact line designs S20 and S25 at JBV. Th(~ Nmweqio:n Jernbane111·1 I.-I'! (.JB\') op<'litl<' ,\11 .\C' lr> k\" l(i., Hz n<·twmk wit.It m<'rhei\d c-011(.act line designs
206
Figure 4.103: Pole with OBB cantilevers on the Otztal-Haiming section.
Figure 4.104: OBB, single cantilever in platform area.
S20 for speeds up to 200 km/h and S25 up to 250 km/h. The S25 system was employed for the high-speed Oslo-Gardermoen iine with line speeds up to 250 km/h. This contact line system with stitch wires is shown in Figure 4.105 [4.25]. Low maintenance cantilevers permit adjustments of the stagger to adapt to track position changes by means of a catenary wire clamp moveable on the top tube. Single poles are most common on the open track. ·wheel tensioners with a gear ratio of 1:3 as shown in Figure 4.106 separately tension the contact wire and catenary wire. Five-span overlaps are the standaxd design The portal structures with solid-wall poles in station areas as shmvn in Figure 4.107 an' based on a modular system that permits adaptation to various cross sec:tiou widths.
4.8 Implemented
C()I_1t.act;
line systems ____ .
________________________________207 _:_:_
Catenary wire Bz II 70 HCA= 15 kN
E cq_
0
~ - - - + - - r - ~ - - ~ - ~ - - ~ - ~ - - ~ - - t ~ - , - , , - + - ~ - + - - Contact wire CuAg AC-120
__ j _______
18
6_._9_,1_7_m_ _ _ _ _ _-__ 1
5,0 m
5,0 rn
·, m
•
Hew
15 l
65,0 rn
Traci< centre line
~ Contact wires
Figure 4.105: Layout of JBV, S25 overhead contact line design.
Figure 4.106: Tcnsio11i11g device for .JBV design (Photograph: Pcdcrscu, Tltorlcif).
j,
,...,.._ _ _ _ _ _ _
_
Figure 4.107: Porta.I structure with cant.ilev<\rs and drop verticals for S25 design. ( P ltotogrnph: Pedersen, Thorlei f).
. 4 D<·sigr_1_
Catenary wire copper-clad steel 50 Hc 11 6,75 kN
E 0
C'J ~ , _ _ - t - ~ - - Contact wire Cu AC-107 Hew= 13,5 kN Contact wire pre-sag 60 mm 60,0m
Track centre line
-~--~ Contact wire
I
.i.
Figure 4.108: Layout of overhead contact lines BN 160. Overhead contact line design BN 160 for the BLS group in Switzerland. The Lotschberg-Bahn (BLS-Group) improved the infrastructure and power supply on the Bern-Neuenburg line. This included the development of the new overhead contact line design BN 160 [4.26] shown in Figure 4.108. The overhead contact line consists of a 50 mm 2 copper-clad 8teel catenary wire tensioned to 6,75 kN and an Cu AC-107 contact wire tensioned to 13,5 kN. The cantilever tubes are manufactured from stainless steel, aluminium alloy or galvanised steel, and the fittings from aluminium alloy. The catenary wire support clamp and steady arms are mounted on horizontal tubes to simplify adjustment work. The registration tube is held by a strut on the cantilever. In station areas, the cantilevers are connected to the poles using brackets. The provision of this insulation arrangement permits maintenance work to be carried out on poles, parallel lines and the track area lighting, without the need to disconnect the overhead contact line. The cantilevers can be attached to drop posts on portal structures in multiple-track areas. On the open track, single poles are the most common and they allow electrical and mechanical separation of the contact line equipments. Separate poles for each support (Figure 4.109) in overlaps avoids large torsional moments on poles . 4.8.2.3
Overhead C\.mtact line for AC 25 kV 50 Hz
High-speed overhead contact lines on the Madrid-Seville line. The MadridSeville high-speed line of the Spanish State Railway (RENFE) was completed in 1992 between r\!laclricl and Seville. The overhead contact line design with a catenary wire, Bz 70 and a contact wire Cu AC-120, is similar to the DB design Re 250. Differently from German practice, return current conducton, are mo1mtcd on the poles to improve the current return. T'hc turnouts and crossovers are wired with intersecting overhead contact lines. Neutral sections separatP the sc\ctions suppli('d by iucliviclual substations in the case of AC 2G kV f">O Hz tr,1ctioll pow<'I supply.. Tli<'\ an~ also used to separate
iI
LK l111plc•111c•11tc•cl cc11!1;icl li1H' S\'Si<'IIIS
:2( )()
Figure 4.109: l)ol<~ pair i11 ov<\rlap:-; of Liit.:-;d1ling-Bah11 (Swit,:,,;<\rla11d) (Photograph: Wii,ckcrlig, Walter).
Figm·c 4.110: \L1d1id S<·,illc· l1igl1-sp<'<'d li11<'. 11c•11l1;d sc•c-liC111 l)('l\\<'<'11 Sllj>i'I\
l)(' a11d
1\C pow
210
________ 4__:D_e_sig~C>L Cot!~_act lines and cross-span equipment
.C:::.: Return current cable or feeder line ACSR 288 mm2
~ Negativ Feeder ACSR 288 mm 2
E
Catenary wire Bzll 65 HcA= 14 kN
0
~
TR Track centre line
0,20m
0
Contact wire
I Figure 4.111: Design of overhead contact line on the SNCF Paris-Tours line.
sections supplied by DC 3 kV and AC 25 kV (Figure 4.110). Overhead contact line on TGV sections at SNCF. The French State Railway SNCF operates a 8237 km network with the single-phase AC 25 kV 50 Hz traction power supply system. From previous experience, SNCF have developed overhead contact lines for high speeds. On 18.05.1990, a TGV train travelled at a world record speed of 515 km/h on the Paris-Tours line. This overhead contact line design is shown in Figure 4.111 [4.7]. Figure 4.112 illustrates a single pole with cantilever and a support for the .AC 25 kV negative feeder. The design of the contact wire registration permits a contact \\·ire lift of up to 400 mm [4.27]. While concrete poles are predominantly used in German>·· Austria and Russia, H-beam steel poles are widely employed in France. The wheel tensioner with a gear ratio 5:1 provides length compensation for the contact wire and catenary wire. The overhead contact line in crossover areas is registered tangentially, that is without crossing between negotiated contact wires. This is due to the long length of the crossovers and the narrow pantograph width of 1450 mm. Portals carry the catenary supports in this case (Figure 4.113). Overhead contact line on Tokaido Line in Japan. The Japanese Railway (JR) moved from the Cape gauge of 1067 mm used for railways in Japan and adopted the standard gauge for the construction of the Shinkansen. The Tokaido high-speed line, which is operated with a traction power supply system at AC 25 kV 60 Hz, permitted a speed of 210 km/h when it was commissioned in 1964. The compound overhead contact line equipment with an auxiliary catenary ,vire, developed for this, ensures uniform elasticity (Figure 4.114). The steel c:cttenan· ,vire with a cross section of 180 mm 2 is tensioned with 25 kN, the copper cadmium auxiliary catenary wire with a cross section of 150 mm 2 and the hard copper contact wire with a cross section of 170 mm 2 are each tensioned to 15 kN [4.28]. One steady arm fixes the contact wire stagger aL 150 mm and another fixes the cm.Tiliar·y cafenary wire. Both steady arms a.re aLt ached to tlw registration arm. The conract wire height is 5,0 rn. The cate11an· win' ca11 he' 111ovc~d a.long tlw top tube to suit the track
I
4.8 Impler~1~:_ntccl contact lir1e systems
211
\
Figure 4.112: Single pole with pull-off contact wire support on the SNCF Atlantic line.
Figure 4.113: SNCF highspeed line, portal for the installation of supports above cn>ssovcr~;
___ 4 _Design of contact lines and cross-span equipment
212
Catenary wire
E
St 180
HcA= 25 kN
lf)
Catenary wire Cu 150 H H
4=3=~.L::.:..::::t.:::_:-::_:-r-:..::::..=-.t::_-.:_-:i;~~===~±=t._::t--__,__ 4 ·10,75m
E
--------------------1
0 0
TR
Contact wiro Cu AC-170
15 kN
Hew=
15 kN
tContact wire pre-sag 50 mm
50,0m
l{)
0,15 m
Track centre line
0,15m
I-
-~-
-1Contact wire
Figure 4.114: Design of the overhead contact line on the Tokaido high-speed line, Japan.
Figure 4.115: Tokaido line, cantilever in Tokyo station (Photograph: Keindl).
geometry. In case of push-off supports the catenary wire can be moved between the pole and the cantilever encl. The pull-off support permits the movement of the catenary wire along an overhanging section of support tube. An adjuster plate with drilled holes is located on the top tube to retain the catenary wire clamp and for the connection between the cantilever tube and the top tube (Figure 4.115). Damping elernents inserted between the contact wire and the auxiliary catenary wire are designed to lirnit oscillations in the contact line system (Figure 4.116). The contact wire is attached to the 11uxiliary cateuary wire by means of rigid droppers with unlimited uplift. vVhile single pol(\S are pn,d0t11imu1t 011 the open track, portals support the contact lines in station areas. The tl'11sio11i11g s<\ctiou lengtlis n.re 1500 1t1. Fiw-span overlaps provide transitions betwee!l th<~ individual tension lengths. Contact line type Re 200C on Harbin-Dalian line in China. This important railway line connects th<' citi<'s of Harbin, Clmngdmng, Sh<'tlg\·crng and Dalian all having mm<~ 1.lirrn oue million i11liahitants. This litw is <'s1wciallv st1il
I
I
213 1:8}rnplement.cd cont.act, line systems
Figure 4.116: Tokaitlo line, damping device between contact wire aud auxiliary catcnary wire (Photograph: Keindl).
Figure 4.117: Overhead contact line design Re 200 C for the line Harbin-Dalian in China (Photograph: Goldammer).
Figure 4.118: Cautilcver of the ov<\rltcad co11tact li11e Re 200 C iu Slwuyaug (Photograph: C:olda11111tcr).
I !
:\, i
i!
214
___________4_ D(!Sign of conta.. t lines and cross-span equipment
Figure 4.119: Poles in front of the main station Kuala Lumpur (Photograph: Rister).
due to a transport of seven million tons of freights and 25 trains per clay and direction for passengers having headways of 8 to 10 minutes [4.29]. The design of the adopted overhead contact line type Re 200 C is based on DB's overhead contact line Re 200 and takes care of the local clirnatical conditions. This is especially true of the temperature range between -40°C and +80°C being 20 K more than that of DB's Re 200. The main tracks are equipped with a contact wire CuAg AC-100, the secondary tracks with contact wire Cu AC-100 both combined with a catenary wire Bz II 50 (Figure 4.117), the tensile force being 10 kN in both cases. The 14 m long stitch wire is tensioned by 2,3 kN. Cantilevers and fittings made of aluminium alloys guarantee a long life cycle period (Figure 4.118). On the open line directly embedded slackly reinforced concrete poles are used and in stations steel poles or concrete poles set on concrete foundations cast in-situ. In parallrl to the overhead contact line equipment a reinforcing feeder AAC 240 and a return conductor AAC 240 as well are strung. The return conductor is arranged closely to the reinforcing feeder to achievl' a close inductive coupling such that a high portion of the return cwrent flows in the retmn conductor. This reduces the reactance considerably. The elcc:trornagnetic field within the contact line area is very narrow clue to the return conductor. This reduces the rnagentic field strength in th<) range of ueighbouri!lg cable installations and, th(Tdon\ the interference. Guiding or rd11rn conductors p(~rmit,s a si111pl<' ,111d lm\·-rnai1tl('I1.--rnce tract ion <·,uthing of the
4.9 References ___ .
cantilevers, poles and other parts of the overhead contact line. The permissible current carrying capacity of 1270 A for this typr. of contact line secures a high power transmission for the transportation of a high nurnbcr of trains and high loads in the future as well. 25 kV overhead contact line SICAT S 1.0 for the line Kuala Lumpur main station to airport in Malaysia For the rail connection of the new airport to the Kuala Lumpur downtown area the Express Rail Link Sendirian Berhad (ERL SB) erected a new railway line in 2001. The 25 km long line is negociated by nine trains per hour in both directions with IGO km/h. The line has been equipped with the Siemens overhead contact line design SICAT S 1.0. The contact and catenary wire commonly tensioned with 24 kN are supported by cantilevers made of aluminium alloys arranged at individual H-beam steel poles (Figure 4.119). The span length of G5 m is adjusted . to the climatical conditions. Tensioning devices with a gear ratio of 1:3 are used to keep the tensile forces constant. Within the Kuala Lumpur main station an overhead conductor rail was installed (Figure 2.19) which is not prone to breakage and, therefore, avoids cost-effective earthing measures.
4.9
References
4.1 DB: German railway directive Gbr 997: Oberleitungsanlagen (German Railway Directive 997: Overhead contact lines). German Railway, 1997. 4.2 Brodlwrb, A.; Senmw, M.: Simulationsmodell des Systems Oberleitungskcttenwerk und Stromabnehmer (Model for the simulation of the interaction between overhead contact line and pantograph). In: Elektrische Bahnen 91(1993)4, pp. 105 to 113. 4.3 KieBling, F.: Projektstudie ,mr Entwicklung einer Oberleitung fiir hohe Geschwincligkeiten (Studies for development of a contact line for high speeds). Siemens AG VT 3 Overhead power lines, 1992.
4.4 von Li11gen, J.; Schrnicf/;, P.: Wanneiibertragung und Strombelastbarkeit von Hochgeschwindigkeitsoberleitungen im Tunnel (Heat transfer and current capacity of high--speed overhead contact lines within tunnels). In: Elektrische Bahnen 94(1996)4, pp. 110 to 114. 4.5 Bauer, K.-H; KieBli11g, F.: Die Regeloberleitung in den Tunneln der N<\ubmrntrecken der DB (The standard overhead contact line within tunnels of German Railway's new high-speed lines). In: Eisenbahnter-hnische Runclschau 3G(1987)11, pp. 7UJ t.o 728. 4.6 Kie/31ing, F.: Vortrag auEi.sslich den Siemens Bahusymposiums (Cout.rihut.ion to Siemens railway symposium). Erlaugcn, 1985. 4.7 Clwrnhron, B.: La co1Hluite du projet TGV Atlantique ct !es travallx de gt11i< civil. In: Revue G<-'nfaalc) des Clwrnins de Fer (198G) 12, p. 5G7. 1
:LS Barwr, IC-H.; I
216
4 Des~snof COiltactEnes a1~cl C!OS~'l:-Span equipment
···-··---··
4.9 Siiberkriil.>, I\!I.: Tedmik der Bah11strom-Leitu11gen (Technology of overhead contact lines). Verlag vou Wilhdm Ernst & Sohn, Berliu, Miinchen, Diissddorf, 1971. 4.10 Breclwell Willis & Ch [Ad.: Constant tensioning uuit for electrified railways and rapid transit syst
11.11.: Die Regelfahrleituug der D
4.23 Kief31ing, L-<'.; Semrau, M.; Tessuu, M.; Zweig, B.-W.: Neue Hochlei:;tungsoberleitung Bauart Re :3:30 der Deutsdwn Ba.hll (The new bigh-perfonna1wc" overhead contact line type Re:330 of German 8ailwa,y). 111: F,]ekt.risdw Uah11cll 92(1994)8, pp. 234 to 240.
4.9 Refer:enc~es
... ---
217
4.24 I<'ll:iip.fer, S.; Christoph, L.: I-Iochgesd1windigkcit.sstrcckc Berlin Hannover 1998 in Betrid> (Ha.1111over I3m·lin high-speed line operative iu UJ98). In: EiseubaJmtechnische Rumlschau (1997)46, No. 9, pp. 531 to 532, 535 to 540. 4.25 Thorese11, Th. E.; qjer/;se11, E.: Ncuc Obcrlcitu11gc11 d<'r :'-Jorgcs Statsbaucr (New overhead contact, lines for Norgcs Statsbaner). In: Elcktrischc Bahncu 94(1996)4, pp. 115 to 119. 4.26 Kodwr, !VJ.: Das neue Fahrleitungssystcrn "BN lG0" cln Bcrn-Ncueubmg Dahn (The new overhead contact line system "BN IGO" of 13<)rn-Nc1wulmrg Railway). Information lnodmre of I3LS. 4.27 L11ppi, .T.; La.111011, .J.-P.: Histoire de la cat.enairc 25 kV. In: Tievuc Generalc des Chcmius de Fer (1992)3, pp. 35 to 52. 4.28 Wa/;,
218
4 Desigr~_c:if contact lines and cross-span equipment
-----~~-
5 Calculations for overhead contact line equipment 5 .1
Assurnptions concerning loads and stresses
5.1.1
Basic principles
Electric traction contact line in:-:;tallations are subjected to rnecha:n1,cal, eled'!"ical and climatic loads and stresses. To ensme reliable transmission of electrical en<~rgy to the traction vehicles, the contact line in:-:;tallations must with:-:;tand all loads and stresses within specific limits, and remain compliant with the requirements of relevant standards such as IEC 60 913 and -3, EN 50 119 and EN 50122 and other national ones. Conductor rails or third rail systems have large cross sections and it is important to take into account expansion and contraction with temperature changes when calculating the dimensions of such con-ductor rail installations. Other climatic factors play a comparatively unimportant role in these systems. Relative to this, calculation of the dimensions of overhead contact line systems is more complicated. Overhead contact hne systems comprise both the live longitudinal contact line equipment and the lateral and vertical supporting structures that suspend the contact line equipment. This chapter deals with calculations for determining the mechanical dirnensions of the contact line equipment. Contact wires and contact line equipment are subjected to vertical and horizontal forces which displace these elements. These forces are referred to as "load.c;" in this chapter. According to the definitions of EN 50 119, the following loads on overhead contact line systems must be considered: dead weight of all conductors, wires and other elements. maxirnurn pennissible tensile force on conductors and wires and their accessories. wind loads on conductors, wires, poles and cantilevers. additional or superimposed loads in the form of installation loads and ice loads. transient load.c; which may be caused by breaking or reduction of forces acting on wires and ropes.
Dead loads
5.1.2
The de.ad load 011 overhead contact lin<~s results from the 'self' or ·dc~ad · W<'ight of wires, conductors, insulators, clamps, stitch ,vires and fittings. Tlws<' are described as a whole by the 'mass pe'r unit, lcn_qth, n1', calrnlated relative t.o the meau support sp<'c:ing. Expn~ssed in general terms, the force due to gravity acting ou a c
-,/
(,
I
-- ///. _(J
(5.1)
220
··-·---·---------5- Calculatic)tts!~_()verhcad contact line equipment
Table 5.1: Mass per unit length and load per unit length of new, unworn contact wires, coudnctors and catenaries. nun-
kg/m
G' N/m
80 100 120 150
0.71 0,89 1.07 1.34
6,98 8,73 10,48 13,10
10 16 25 35 50 1 ) 70 95 120 240 625
0.090 0.143 0.218 0,310 0.-1-16 0.596 0.845 LOGO 0.670 1,732
0,88 1,40 2,14 3,04 4,38 5,85 8,29 10,40 5,57 16,99
G' N/m
G'
G'
l\'/m
N/m
A
Design a tio11
711 •)
Copper a11d copp<'t a.lloy cables AC- 80 AC-100 AC-120 AC-150 Conductors of E-Cu and wrought copper alloy Bz II
Aluminium conductors Designation Contact line equipment Contact wire Catenary wire Droppers Clips Stitch wires Sum value used in planning 1) seven-strand
Re 160/2002 ) 8,73 4,35 0,11 0,19 0,15 I: 13,53 ~ 14,00
1
Re 250 2 l 10,48 5,85 0,20 0,40 0,85 I: 17,78 ~ 18,00
Re 3302 ) 10,48 10,40 0,20 0,40 0,85 I: 22,33 ~ 23,00
2) DB standard contact line system
where g is the ru:r:eleration due to gravity. Table 5.1 shmrn the masses and loads per unit length, of commonly used contact wires, conductors and contact line equipment. The load per unit length of a contact wire of cross section area Acw and with a specific mass of ,cw is calculated using the following equation: G~.:;w
= -lcw ~:< :w /102
Acw
N/m
')
rC:v\l
(5.2)
llllll-
Stranded conclu.clm s 111-tv<' i11dividnal strands up to 3 % long<'r than tlw actual conductor length. The dead load due to fittings, droppers and other fittings may differ from one span to the 1wxt. In practical design a.11d planning ,vork, the self weight of these co111po11cnts is del('.l111i1wd for a typical span length, and
5_1_ Assumptio11s coucen1ing loads and stresses
221
Table 5.2: Material properti<~s of conduct.on-: in accordance with DIN 48 201 and contact wires iu accorda11cc witlt EN GO UHJ. Nominal ('.["OSS-S(\('.f ion
Sp
Nnmlwr of
(T(lSS-S(!cf.iOII
strauds
•)
•)
Jlllll-
llllll-
Co11duc:t01s 10 1G 25 35 50 50 70 95 120 240 400 625
10,02 15,89 24,25 34,36 49,48 48,35 65,81 93,27 116,99 242,54 400,14 626,20
Dia111d.er 111111
7 7 7 7 7 19
19 19 19 61 61 91
4,1 5,1 6,3 7,5 9,0 9,0 10,5 12,5 14,0 20,3 26,0 32,6
Contact wires Cu AC-100 CuAg AC-100 CuMg AC-100
100 100 100
12,0
Cu AC-120 CuAg AC-120 CuMg AC-120
120 120 120
13,2
Cu AC-150 CuAg AC-150
150 150
lcl,5
5.1.3
Tensile forces and their co1nponents
5.1.3.1
Tensile forces acting on conductors and wires
The tensile .fmn's acting ou and withiu conductors and wires of overh<'ad cont.act lines are determined b_v structural design principles. The tC'usil{' forces 011 co11tact and cat
222
_ _ _ _ _5_C_'c_lkulations for overhead contact line equipment
Table 5.3: Factor kumip for contact; wires in accordance with EN 50119.
wire type
Maximum operating te1111>craturc G0°C 80°C 100°c
Cu CuAg,0,1 CuMg0,5 C11Sn CuCd
1,0 1,0 1,0 1,0 1,0
Contact.
0,9 1,0 1,0 1,0 1,0
0,9 0,95 0,90 0,95
Table 5.4: Factor k1oad for contact wires in accordance with EN 50119. Design of overhead contact line CW and CA automatically tensioned C\Y automatically tensioned, CA fix
= contact wire;
CA
Wind and ice load
Wind load
0,95
1,0
0,90
0,95
0,77
0,80
= catenary wire
equation: Fper
= 0-perA
(5.3)
EN 50 119 states that the maximum permissible tensile stress under operating conditions should be calculated as follows a per
= a min · 0,65 · ktcmp
· kwcar · k1oad · h'cff · kc1amp · kjoint
(5,4)
where the abbreviations in equation ( 5.4) indicate: O-min minimum tensile strength; ktemp factor which gives the relation between the maximum operating temperature and permissible tensile stress, examples of these values are given in Table 5.3; kwear factor which expresses the permitted maximum wear, e.g. kwear is 0,8 for a maximum permitted reduction of the cross section to 80 % of its nominal value; k1oac1 factor which expresses the effect of wind and ice loads, the recommended values are given in Table 5.4: keff factor used to describe the characteristics of the tensioning equipment, in normal designs, keH can be assumed to be 0,95 in the calculation; for designs of greater accuracy and an efficiency of more than 0,95, it is permissible to assume keff = 1,0; kc1amp factor used to describe the characteristics of the tensioning clamps; if the force that can be transmitted by the clamps is greater than 95 % of the nominal tensile force on the contact wire, this factor can be assumed to be 1,0 and kioint factor which describes the reduction of the tensile strength due to welded, brazed or soldered joints, this is normally 0,95. If no such joints are used, a value of 1,0 is assigned to kinillt in the equation. The operating tensil<\ stress may not <)xceed G5 % of the nominal tensile strength of the contact win~.
5.1 Assumptiousc<~uc:ernin_gloa.ds_a.nd stn)SSCS.
Table 5.5: FacLor ki.e,np for cat.cnary wires in accordance with EN 50 119. Type of c:atenary wire Cu Al-alloy CuAg Cu Mg-steel
223
··-······---·-···-···-·-------
Table 5.6: Factors !.:wind and kice for catenary wires in accordance with EN 50 119.
maximum opera.ting tc1nperatt1n\ G0°C 80°C 100°c
Type of tensioning
1,0 L,0 1,0 1,0
automatic tensioning
1,00
fixed at both ends
0,95
0,9 0,9 1,0 1,0
0,80 0,85 0,95
up to IJW
kw ind above 100 km/It
0,% O,DO
X:icc
0,95 0,70
Example:
What is the maximum permissible operating stress of a contact wire of type Cu AC-100 in a DB-standard overhead line installation with fully compensated contact line equipment and with welded joints? From the tables, it is obtained: O"min = 355 N/mm 2 , in accordance with EN 50149, ktemp 1,0 for ·i9rnax = 70°C, from Table 5.3, kwear = 0,80 at a maximum permitted wear of 20 %, k1oad = 0,95 in accordance with Table 5.4, keff = 0,95 efficiency of the tensioning wheels 2: 0,9, kc1amp = 1,00 because the tensile force transmissible by the dead-end clamp 1s greater than the nominal tensile strength of the contact wire and kjoint = 0,95 because welded joints are used.
In accordance with equation (5.4), the maximum permitted tensile stress is calculated to be 150,4 N /nun 2 . For the wire under consideration, the permitted operating tensile force is therefore 15 kN. This value is higher than the value of 10 kN as obtained by using equation (5.3) and the maximum permissible tensile stress according to the former DIN VDE 0ll5. Hence the safety margin against breakage, calculated using equation (5.4) is 2,36 and that calculated using to equation (5.3) is 3,55.
Analogously, acc:orcliug to pr EN 50 119, the following applies to wires used in overhead contact line installations: Clper -
Clmin ·
0, 65 · ktemp
· kwind · kice · kcff · kc1amp · k1oad
(5.5)
For equation ( 5.5), factors A\emp may be taken from Table 5.5, kwincl and kice from Table 5.6. Factors kerr and kc1a,np are defined in the same way as for contact wires. The factor k 10 ac1 is used to describe the effect of individual loads on the catenary wires, e.g. section insulators. If no other vertical forces act on the wires, the value k1oac1 - 1 is used. For vertical loads which act on cross-span ,vires for example, the factor k10 ac1 0.8 should be used in the calrnla.tions. What is the maximum permissible stress in a 50 nun 1 cat<)t1,uy wire of Bz II in a DB-standard overhead li,w installation in accordance with EN 50110 with a wind velocity of 26 m/s?
Example:
From the tables, it is obtained:
=
578 N/rn11? in an:orda11ce wit.It DlN 48201, 1,0 in il.
224
5 Calculations for ov~r_!l<~c~d cont;act line equipment i+1
i-1 V; ---NN;
H ----+-----NNi+1
kwind kice kc1amp
=
1,0 in accordance with Table 5.6, as
Figure 5.1: Effect; of different suspension point heights on the support reaction fon:es.
vwincl
= 93.6
km/h < 100 km/h,
= 0,95 in accordance with Table 5.6. = 1,0 and 0,8 because a section insulator is installed.
k1oad
Using equation (5.5), the maximum permissible stress is calculated to be 285,5 N /111111 2 assuming ktoacl = 0,8. If the factor k1oacl 1,0 1 more frequent!>' the case. the maximum permissible operating stress would be 356,9 N /mm'2 . Depending on whether the catenary wire is subjected to vertical loads or not, the corresponding maximum permissible tensile force on this conductor would be 14,13 kN or 17.66 kN respectively. For ktoacl = 1, a failing safety margin of 1,62 is obtained. This must be compared to the value of 1,96 calculated in accordance with former DIN VDE 0115. For k1oad = 0,8, the respective safety margin is 2,02.
5.1.3.2
Components of the tensile forces acting on conductors
Vertical components of the tensile forces Where deviated through a change of direction the tensile (axial) forces acting on conductors and wires introduce vertical and horizontal load components. Let H be the horizontal force acting on a wire or conductor. The dead weight G acting on a conductor of length L is calculated using the weight per unit length G' of the conductor, G - G' L. In overhead contact line design, it is possible to substitute the support spacing l for the conductor length L with an error of approximately one in a thousand. Thus the w<~ight is:
G
(5.6)
G' l
The components of the reaction forces on the supports of one span are calculated using the halcrnce of moments ,vith the dimensions shown in Figure 5.1.
where ,\'V, is a relativc height in rclntion to a c:omrnon reference height. The entire ,c'1tical react,ion fon-e on a support is I; -- G' (Ii+ /i-ti) /2 + H [(.VNi - NNi
1)
/Ii+ (VNi
SN;+ 1 )
/
(+i]
(5.7)
If the neighbouring supports are higher than the s11pport under consideration, the reaction fore<~ is red11< <'d If the'\ an' lom'L t ]l(' r<',1Ction fore<' is inCT<\ased.
5.1 Assump~o~1~_concerning loadR and st,reRseR __
i-1
i 11
C
C
-b
-
direction or line
+b Ii
ii11
225
Figure 5.2: Horiwntal component FH of the tcusile force H acting on the conductor due to the alternating lateral offset b of the wire (termed stagger).
Horizontal components of the tensile forces Changes in the direction of conductors and contact wires cause lateral forces. The changes in conductor direction occur because of:
wrves in the track - lateral offset to achieve stagger in contact wires and cables - lateral deffoction towards anchoring points or tensioning equipment Along straight (tangent) stretches of track, the horizontal components are the result of the stagger and the anchoring geometry.
Stagger ( contact wire zig-zag). From Figure 5.2, the following relationship, with alternating signs, can be deduced: tan a
= (bi -
bi+1) /li+1 ~ sin o: -
F11
i/ H
The approximation tan a ~ sin c:1: applies for small angles. For example, the error 1s 1,5 % for an angle of o: = 10°. The force Fl-Ii -
H [(b; - b;-1) /li + (bi - bi+1) /li+il
(5.8)
is the horiiontal component of the tensile force on the conductor required to pull it away from the centre line. For the situation that bi - b and bi-l = bi+i - -b and li+ 1 = li l, as is the case along a straight stretch of track, the equation is simplified to F11 -
(5.9)
4H b/l
Example:
In DB standard overhead contact line im,tallations for up to 200 km/h running speeds, the values b = 0,4 m and H = 10 kN apply. Assuming a pole spacing of 75 111 the horizontal component of the conductor tensile force is calculated to be 213,3 N corresponding to 2,1 %. 1
Fixed anchoring or automatic tensioning. Using the same approximation as before, the horizontal component of the force clue to a lateral offset z towards an anchor or tensior1:1:ng ·mechanism., as shown in Figure 5.3, would be
F 11
H sin n'.
~
H tan n
and correspondingly
(;)_10)
I!
226
5 Calculations for overhead contact line equipment
i+1
'·~ . . .
z;
a
.
Figure 5.3: Horizontal component of the conductor tensile force due to anchoring or tensioning equipment.
Zi+1
i-1
i+1
Figure 5.4: Horizontal components of the forces acting on a mid-point anchoring pole due to lateral anchoring offset.
If all l values are equal and all z values are equal and the half-width of the pole is ignored, the simplified equation is (5.11) .A.long a level track without super-elevation, the distance z = half the pole width + l'vIFE, where MFE is the distance between the pole front edge and the track centre line. In the following explanations, the dimension MFE at pole number i is designated lAi· For a mid-point anchoring pole, the following equation applies: (5.12) This is simplified as follows if the distances z are equal and the support spacing is uniform: FH
= 2 H (lA + half pole width)/l
(5.13)
Example:
For a mid-point anchoring pole as shown in Figure 5.4 with a distance lA-;::::; 4 m, a pole spacing of 65 m and a contact wire tensile force of 10 kN acting horizontally on the anchor rope, the horizontal component acting at right angles to the track centre line is calculated to be 1,23 kN.
Curved track. On bends and curves, the horizontal components of forces acting on the conductors of overhead contact line installations are clue to the pulling of the line along the curve, the stagger and the anchoring forces. From Figure 5.5 the following formula can be deduced for a curved track with curve radius R:
5.1 Assumpti()~l~ concerning loads
and stresses
_ __________________ _
227
\ \ \ \
\ \ \ \ \ \
I;._
\ \
--'
\ Track centre line
-
I
-
T
b,
t:,L,
Figure 5.5: Horizontal components of conductor tensile forces in a curve.
Figure 5.6: Change in t.he lateral offset of a contact wire by flb due to the change in position of a cantilever of length l_:.._ i, initialized by thermal expansion or contraction by fl Li.
The curve pull-off force, which is often also termed the radial load, is the sum of the horizontal components of the conductor tensile force in the t,rn adjacent spans, (5.14) and, in the case of uniform spans, the equation is simplified to
FH
= Hl/R
(5.15)
To take the additional lateral offset into account, a further component is adclPd: (5.16) At an anchoring pole, for a pull-off in a curve, according to (5.12) and (5.1-!)
and for the mid-point pole with automatic tensioning of contact and catenan wire (5.18)
Thermally caused changes in the lengths of wires and conductms will induce changes in the stagger and the related horizontal ('.Omponents. _-\ d1ang(' ~b in t lie stagger may occur due to the tlienn.-11 expansion or contraction of the contact. and c,1t.enary wire by 6L as shown i11 Fig11n~ 5.G. By applying the equation i - ilh,)2 + flL/, an approximation or cha.ug<' in stagger, ignoring the square terms (Jf ~/;, is gi\<'tt by:
rt (/.\
(5.19)
228
/A,
5 Calculations for overhead contact line equipment
i I I I I
/-/
I/-/
Figure 5. 7: Resetting forces 6..Hru acting on a cantilever of length lA i due to change in position by a distance 6..Li.
Resetting forces (also known as cantilever drag). The change !:::..Li, in the position of the cantilever leads to the curve or pull-off forces exerting a moment around the cantilever's axis of rotation. This moment is opposed by a moment due to the difference of the horizontal components of the contact wire forces. This difference is termed resetting force. Part of the horizontal tensile force is exerted on the pole. This resetting force is calculated applying the approximation sin O'. ~ tan a, which is permissible for small angles, and as shown in Figure 5. 7, to obtain the equation (5.20)
In relation to the catenary wire, lA is the distance from the track side face of the pole to the center of the catenary wire clip. The sum of the resetting forces within half an automatic tension length must not be greater than (0,07 to 0,08) · H [5.4]. If the temperature drops, the contact wire tensile force increases by the sum of the resetting forces with increasing distance from the tensioning device. If the temperature rises, the contact wire tensile force decreases accordingly. \,\,rhen planning contact line installations, it is important to ensure that the tensile forces in contact wire and catenary wire are as nearly equal as possible on both sides of the anchoring mid-point support. The resetting forces at each support within half a tension length can be calculated by applying equation (5.20). The maximum contact wire tensile force change in the vicinity of the mid-points is of interest. This can be expressed in terms of the sum of the resetting forces. For the last span before the mid-point anchor, the total change in longitudinal force on the contact wire is n-1
!:::..HR -
L F1-1i l:::..Li/lAi
(5.21)
i=I
Along straight st:r-etches of track, the resetting forces acting at individual supports are the result of the contact wire and/or catenary stagger in accordance with (5.8). However, as the lateral forces along a straight stretch act in opposite directions from on<' support to the next, the resetting forces virtually cancel each other, Here too, the individual resetting forc<~s ,tre calc:ulatecl using (5.20). Along r.·urves where R, /, and l,\ are constant, the resetting forcr~s will be calculated using (5.14), (5.20) and inserting 6L; i In: ,6.t?. This results in: 6HI(,
= 1. /2 0' 6d H /(R !,,)
(5.22)
5. l ~ Assumptious coricerning _loads aud stresses
" " " · - - - - - - - - - - - - - 229 --
In the last span before the mid-point anchor, tlw difference to the horizontal tensile fore<~ in the centre position is (5.23) The cantilevers of an overhead contact line dcsign<:d for ·19min - -30°C and Dmax = 80°C (difforcnce 110 K) have to be adjusted in such a way that they assume their mean or nominal position at a temperature of 25°C.
Example:
For a copper 100 K overhead contact line with an automatically adjusted tensile force of 10 kN in a curve of radius 250 rn, 10 spans of 38,6 m and cantilevers of 2,5 m length, the reduction or increase of the horizontal tensile force due to a respective temperature increase or decrease of 6.rJ 50 K is calculated to be 912 N. Using the calculation according to [5.5], which is considerably more complex, a value of approximately 820 N [5.6] is obtained. With a reduction of the tensile force by 912 N, the sag in the span before the mid-point support and of the catenary system will increase by 28 mm. The contact win~ sag between two consecutive droppers spaced 12 m apart will increase by 1,6 mm.
The resetting force calculation presented here is an approximation, because there is an assumption that (a) the cantilevers will be aligned correctly at a specific ambient temperature and (b) the steady arms are also able to pivot about their end joints. Additional resetting forces arise due to friction in the cantilever joints and the tensioning equipment. Measurements carried out on a standard overhead line of DB type Re 250 have shown that these friction-induced forces in a tensioning mechanism are roughly equal to 2 % of the horizontal force.
5.1.4
Wind loads
The wind load8 on the individual elements of overhead contact line installations depend on the vVill(l velocity, the shape of the area exposed to the wind and the wind direction. If no specific other data is given, the following equations assume that the wind direction is normal to the overhead contact line. \Alim! forces act in a, horizontal direction. If the area exposed to the wind is Aw, then the force <~X<\1ted by the wind, called wind load in the following, is given by the equation: (5.24)
Fw - cw· q · Aw
where the wind pressure q 1s related to th<' wind velocity vw as expressed by the cq11ation
r: ')•) ( c.l.~c.l
(1/2) · ''/ · v~v
According to EN 50341-:3-4, the drnsity of air at :20°C is 1 -- 1,2:iO kg111 applications tlw following equation is th<'rcforc acl1incd:
= ·u~v /
(j
l,G
:i
Ii\\
Fm practical
(5.26)
230
5 Calculations for overhead contact line equipment
Table 5. 7: Wind loads per unit length and aerodynamic drag factors of components of overhead contact line installations. Component
cw
Double-channel poles UlO0 U120 U140
8 m long 8 m long 12 m long Lattice steel poles 600 X 800 L 100 x 10 12,5 m long 800 X 1000 L 120 x 11 16,0 m long Concrete poles NB3R 9,5 m long Contact wires din mm Cu AC- 80 10,6 Cu AC-100 12,0 Cu AC-120 13,2 Cu AC-150 14,8 For twin contact wires: 1 ) as._6-d: cwct = ewe · 1,6 a> 6-d : cwct = ewe · 2,0 Stranded conductors A in mm 2 din mm Cu 10 4,1 (dropper) Cu 16 5,1 (dropper) Cu 25 6,3 (stitch wire) Cu 35 7,5 (stitch wire) Cu 50 9,0 (catenary wire) Cu 70 10,5 (catenary wire) Cu 95 12,5 (catenary wire) Cu 120 14,0 (catenary wire) ACSR 185/30 19,0 ACSR 240/40 21,8 ACSR 300/50 24,5 AAC 240 20,3 (parallel feeder lines) AAC 625 32,7 (return lines) Contact line system Cu AC-100 + catenary wir<:' 50 mm 2 Contact line system Cu AC-120 + catenary wire 70 mm 2 Contact line system Cu AC-120 + catenary wire 120 1111112 1)
1,7 1,7 1,7 2,8 2,8
Wind load per unit length in N/m for vw = 26 m/s vw = 37,1 m/s narrow wide narrow wide side side side side 116 180 140 220 134 180 170 220 170 210 210 260 270 280
300 300
550 630
590 660
0,7
180
360
1,2 1,2 1,1 1,1
5,37 6,08 6,13 6,88
10,94 12,39 12,49 14,00
1,2 1,2 1,2 1,2 1,2 1,2 1,2 1,1 1,0 1,0 1,0 1,0 1,0
2,08 2,59 3,19 3,80 4,56 5,32 6,34 6,51 8,03 9,21 10,35 8,58 13,82 11,5 13,1 13,7
4,23 5,26 6,50 7,74 9,29 10,84 12,90 13,25 16,34 18,75 21,08 17,46 28,13 23,0 26,2 27,4
a is the distance between the parallel contact wires. The drag factor is related to the area of a contact wire exposed to the wind.
5.1 Assurnptionsconcerning loadsand.stresses
231
The aerodynamic coefficient of resistance or drag factor, cw, depends on the shape and surface characteristics of the body exposed to the wind (cf. Table 5. 7). The wind load per unit length on cables and wires of a diameter d is expressed by the equation:
F tw
2 2 = F w / l = (l I 2) · 1 · vw · cw · Aw/ l = (1/ •2) · 1 · vw · cw · d
(5.27)
Table 5. 7 shows typical wind loads per unit length and the drag factors of the essential parts of overhead contact line installations.
5 .1. 5
Ice loads
In the following discussions, the weights acting due to ice, hoarfrost or snow are all collectively termed ice loads. Maximum ice loading may be a rare event. From observations of ice formation, calculation values for ice deposits on suspended conductors have been derived and used from standards pertaining to overhead power lines. The ice loads can be classified according to two main types: Ice formation clue to precipitation. In this case solid clear ice is formed (density approx. 0,9 A/ni) by S'Upercooled rain or drizzle at near-freezing ambient temperatures. Wet snow or sleet (density 0,4 to 0,6 A/m 3 ) also belongs to this category. Ice formation in clouds or from freezing fog. Hoarfrost is formed by supercooled water droplets. Hoarfrost formation is typical for altitudes above the cloud base altitude. Hard hoarfrost (density 0, 7 to 0,9 A/m3 ) and soft hoarfrost (density 0,4 to 0,6 A/m 3 ) occur. Combinations of the various types of ice load may occur. If the characteristics of ice loads are not known from local observations, then the values given in transmission line standards e.g. EN 50341-1 are used. In particular, EN 50341-3-4, valid for Germany states that, for overhead wires and conductors, an ice load per unit length, G\e of
c;ce
5
0,1 d
G'.ce
d
N/m
mm
(5.28)
must be assumed. The equation can be used for contact wires and conductors of a diameter d in overhead contact line installations. Note that operating experience of the German railway companies has shown that larger ice loads are stripped off thr lines by the passage of a pantograph or they drop off due to heating of the wire!-:l. Thus the DB takes the ice load per unit length 011 components of overhead line equipment as being
icc --
( -,, 7
·) r: ~,O
+ () , ()r.
l
;J(,
(5.29)
232
5 Calculations for overhead contact line equipment
y
support
V+dV
Detail
dx
S+dS
X a
X
II 2
s
V
Figure 5.8: Sag in a single overhead conductor.
5.2
Sag
5.2.1
Single trolley-type contact line
5.2.1.1
Supports at equal height
This section considers the sag of a conductor under a specific load per unit length and with contact wires with automatic tension control, that is, subjected to a constant tensile force. Clause 5.3 deals with fixed anchoring at both ends which induces change in tensile force from superimposed loading or temperature changes .. The first case investigated is that of two conductors with supports located at equal heights. Let S be the tensile force acting along the conductor. The \·ertical component of Sis termed V, and the horizontal component is termed H. Since the bending stiffness of the contact wires and conductors used in contact line installations is relatively low, only the tensile forces acting along these conductors must be considered. It is assumed that the conductor has a pivot at the support but is anchored to prevent longitudinal movement. The equilibrium of forces acting on a wire segment of length D..L, as shown in Figure 5.8, is shown to be: for horizontal forces
H+dH
H=O,
~
dH=O
where, by integration H = const, and for for vertical forces V +di. - ii' - G' dL = 0, ~ di. = G' dL \i\Tith dL = d.TJl + (dy/d.1:) 2 and the relation dy/d1: = F/ H, which is deduced from Figure 5.8, the differential equation of the sag curve is found to be
d 2 y/ch 2
(G'/H) J1
+ (dy/ci.1:) 2
(5.30)
The solution of this is generally known as a catenary curve .II -
(H/G') cosh (G':r/H)
(5.31)
5.2
233
as is explained in detail in [5. 7], which can be ratified by inserting the solution (5.31) into the differential equation (5.30). However, in overhead contact lines, the wire length L is only 0,5 to 1 °loo longer than the support spacing l. For this reason the assumption dL ::::::: cfa: can be justified with the result, that the differential equation for the wire sag is simplified to: (5.32) The solution is the parabola equation y
= (G'/H) · (x 2 /2)
(5.33)
Let the sag in relation to the support point be y 1 , cf. Figure 5.8. At any point at a distance a from the support, this is
Y1(a) =fa.= (G'/2 H) · a (l - a)
(5.34)
In comparison, for the sag y 1 as a function of the distance :c from the mid-point of the span, it is obtained: (5.35) The maximum sag is to be expected for a
Ymax - frnax
= l/2
or for :r - 0. This would be equal to
= (G' /8 H) · z2
(5.36)
The sag y 1 at a distance a from the support can also be expressed in terms of the maximum sag .fmax as follows: YI
= fa = 4 f rnax a (l - a)/l 2 = 4 .fmax a (1
- a/l)/l
(5.37)
Example:
The maximum sag of a contact wire type Cu AC-100 subject to a constant tensile force of 10 kN at l = 40 m is
frnax
8,73 N · 40 2 m 2 m · 8 · 10 000 N
= O, 175 m
The same contact wire in a catenary overhead contact line installation with a dropper spacing of 12 m would have a sag of approximately Hi mm between two droppers.
5.2.1.2
Supports at different heights
If the lwight of two consecutive supports of a conductor differs by h, it is possible to apply the dimensions shown in Figme 5.9 and the two partial longitudinal spans l 1 and as well as the~ relationships and/ - 0,5 (/ 1 + /'.!.) und h - f 1 - h
/.2
l ='.2Hh/(G'l)+l attd l'.!.=-2Hh/(G'l)+I 1
5 Calculations for overhead contact line equipment
234
y support catenary wire
Figure 5.9: Sag in a line with supports at different heights.
Figure 5.10: Sag in contact line equipment.
where l1 is the span relating to the higher of the two supports and l 2 relates to the lower support. The maximum sag in relation to the higher of the two supports is then Ji, which is calculated by the following expression after l1 and l2 have been eliminated:
Ji= !max= G' z2 /(8 H)
(h/2) (1
+ H h/(G' l2 ))
(5.38)
The sag fa at a distance a from the higher of the two supports, which is higher than the other by h, is then equal to fa= G' a/(2H) (l- a)+ ha/l
(5.39)
If, as a simplified approximation, (5.39) instead of (5.36) is applied for the maximum sag in equation (5.38), the equation for the sag at any distance a from the higher support is fa= 4 fmax a (1 - a/l)/l
+ h a/l = 4 fmax a (1 -
a/l
+ h/(4 fmax))/l
(5.40)
In overhead contact lines, the height differences are generally small, so that the square terms in h can be ignored.
5.2.1.3
Catenary suspended contact lines
In this context, the term contact line equipment is used to describe a system where the contact wire is suspended from a catenary wire by means of droppers in such a way that specified distances between the c:atenary and the contact wire are maintained by the lengths of the individual droppers [5.8]. The following relationships can be deduced from Figure 5.10:
d Ve A G~A · dLcA dycA/d.T - VcA/ HcA
cl Vc:w
= G~w · dLcw
cw / Hew
dycw /ch= 11
and
The indices CA and CVV indicate the valu<~s for the c:atenary or messenger "·ire CA and for the contact wire CW respectively. Bv differentiation and substitution in the corresponding differential <~quations, tlw following expressions are obtained: 2
HcA d YcA/cl.r 2 = C~:A · dL(' ,/cl.r
') I ') flew cl-yew dr
I
.
- Cnv · d /,c·w /d.1
and
(5.41)
5.2 Sag
__ _____
_
235
By inserting the total mass per unit length of the entire contact line equipment G~HL = + Gc:w and applying the approximation clLeA ~ clLew ~ clx, equation (5.41) results in
Ge:!\
GIOHL Integrating this equation twice with respect to
HeA YcA + Hew Yew = G~Hll, :i: 2 /2 + C1
.1:
;r;
(5.42)
produces the relationship
+ C2
The integration constants are derived from the boundary conditions shown in Figure 5.10 and are
Y~A (0) = 0 YcA (0) = Yorn,
and and
Y~:w(0) 0 -+ C1 = 0 , Yew(0) = 0 -+ C2 = HcA Ymr1,
which leads to the equation
HeA YcA
+ Hew Yew=
-y/
Gom, :z:
2;,2
(5.43)
HcAYom,
If an additional ice load is placed on the contact wire and the catenary wire, the weight per unit length G~rrL of the contact line equipment increases to G~HL,ice = G~m, G(ce, where the term G(cc is the weight per unit length of the ice deposit. As a result, the catenary sag will change by:
+ Hew Ycw,ice =
HcA YcA,ice
2
G~HI, ice J: /2 '
+ HcA YOHL
(5.44)
The contact line equipment is designed in such a way that the contact wire without ice load will have virtually no sag. The catenary wire ·with its tensile force of HcA has to then support the weight of the entire contact line equipment, so that the catenary wire sag can be described, as a good approximation, by the expression (G~mj HcA) · (:x: 2 /2). From this, the following relationship can also be considered to apply : YcA,ice
= Gu111, :1: 2/ (2, HeA) + Yew,ice + Yom, I
(5.45)
The sag of catenarv wire and contact ,vire under ice load, YcA,icc and Yew,ice can then be deduced individually from (5.44) and (5.45). Thus: YcA,ic:e - (:i:'-'/2) (G~-ir 11 ,/HcA
+ G~ce/(HcA +Hew))+ Yorn,
and
(5.46) (5.47)
Similarly to (f>.:3-1), if the sag is expressed in relation to the supports and the variable replaced by Lil<' \itti,1.hlc' u, the following
J'
//1 CA,ict' - (u(/ - a)/2) (G~)lllj Hc:A +
c;cj(Hc:A +Hew))
aud
//1 c:w,ic(' - (n(/ - n)/2) (G;n,/(Hc:J\ +Hew))
The ·marimu'/11. 1:0-11,/11.cl w'/1·1, su._q wit.Ii it<' load will occur at position o. = //2. For this position, the l'ollowi11g is olit.,tiued: (5A8)
236
5 Calcuh!.t.ions for overhead contact line equipment
------
Example:
How much will the contact wire of a standard, main-line overhead contact line equipment sag under ice load between two supports? Without ice load, a contact line equipment of this type should show little sag. Half the ice load stated in EN 50 341-3-4 according to (5.29) is to act on the contact line equipment :
G\ce = 2 · 2,5 + 0,05 (9 + 12)
= 6,05
N/m
Furthermore, if HcA =Hew= 10 kN and l
5.3
= 75
m. The result is then
.fr,iccmax
= 0,213
m.
Physical state change equations
The lengths of conductors and contact wires used in overhead contact line installations will vary both because of thermal expansion and elastic strain from tensile force. A conductor of length L will expand (linear expansion) by (5.49)
when its temperature is raised from {) 0 to 19x, where a is the coefficient of thermal expansion. Tables 2.11, 2.12 and 2.13 show the coefficients of thermal expansion of materials typically used in overhead contact line systems.
Examples:
In all following examples, the change in length of a conductor due a temperature change from 19 0 = -30°C to {)x = +70°C is to be examined. For example, if the values of a given in Tables 2.11 and 2.13 are used, 6.Lw = 0,0185 m for an iron conductor rail of length 15 m; 6.Lw = 0,0425 m for a composite steel/aluminium conductor rail of length 18 m and 6.Lw = 1,275 m for a contact wire of length 750 m. For this reason, iron or composite steel/aluminium conductor rails have to be fitted with expansion joints at 45 to 60 m intervals with supports that will not hinder expansion and contraction. Contact and catenary wires are equipped with equipment to compensate automatically all length variations with the objective of maintaining a constant tensile force. When a linear force is applied to a conductor, its length will change as a result of elastic strain. Provided the applied linear force does not lead to the elastic strain limit being exceeded, the conductor will regain its original length once the force has been removed. The change in a conductor's length due to elastic strain can be calculated if the modulus of elasticity (Young's modulus) E is known. When the force acting on a conductor is increased from H 0 to H:i:, the length of the conductor changes by 6.LE
= (H:i: - Ho) L/(E A)
(5.50)
Examples:
If a 750 m long, Cu AC-100 contact wire, is subjected to a tensile force of 10 kN its pre-tensioned length will increase by 0,58 m. A booster feeder line of aluminium with a cross section area of 240 mm 2 will stretch by 0,045 m within a 75 m section if the~ load i:-1 increased from 0 to 10 kN.
Further, the conductor may be suhject<~d to additional loads, e g ice loads. These additional loads ·will change tlw axial tensil<' loads of co11ductors that are installed
237
5.3 Physical c;t,ate change equations _____ ·--·-·--··--·---------
without automatic tensioning regulation. The following equation is used to determine the length of a sagging conductor between two supports of equal height: d:r
dL
J1 + (dy/cb:)2
From (5.33) it can be deduced that dy/d:r = G' -1.;/ H. Since (C' :r/ H) 2 << l for conductors used in traction overhead contact lines, we can express the preceding equation as dL - (1
+ (C' :c/H) 2 /2)ch
By integrating this over the conductor span length, we obtain the wire length
L = l + (G'/H) 2
3
· ({
(5.51)
/24)
or, if this is expressed in relation to the maximum sag
L = l + (8/3) · (./ 2 /l)
f
according to (5 .36) (5.52)
Example:
The length of a catenary wire supporting a contact line equipment with 14 N/m and subject to a tensile force of 10 kN stretched between supports 75 m apart is 34,5 mm longer than the distance between supports.
If the weight per unit length changes from state O to state x, for instance due to ice loads, the tensile force in a wire without automatic tension control will also change accordingly. This variation is described by (5.53)
The change in the length of a conductor without automatic tensioning when subject to a state change from state O to state :r: is equal to the sum of the changes in length due to thennal expansion and due to elastic strain. Thus,
or, if the individual terms are expressed in full,
Since L
~
l for overhead contact lines, the simplified version given below can be applied
(5.54) Equation (5.54) is the e
5 Calculations for overhead contact line equipment
238
-------
Table 5.8: Sag and tensile stress in a 240 mm 2 aluminium conductor without automatic tensioning, in relation to temperature. Span in rn 67
65
f
79
oc
rn
-30 -20 10 - 51) 0 10 20 30 40 50 60
1,05 1,19 1,32 1,48 1,44 1,56 1,67 1,77 1,87 1,96 2,05
(J
N/rnm 2 13,7 12,0 10,8 20,0 9,9 9,2 8,6 8,1 7,7 7,3 7,0
f
69
f
(J
m 1,14 1,28 1,41 1,57 1,54 1,65 1,76 1,86 1,96 2,06 2,15
N/mm 13,3 11,9 10,8 20,0 9,9 9,2 8,6 8,2 7,8 7,4 7,1
2
73
71 (J
m
N/mm
1,24 1,38 1,51 1,67 1,63 1,75 1,86 1,96 2,06 2,16 2,25
13,0 11,7 10,7 20,0 9,9 9,2 8,7 8,2 7,8 7,5 7,2
2
f
(J
m 1,31 1,48 1,61 1,77 1,73 1,85 1,96 2,06 2,16 2,26 2,35
N/mm 12,8 11,6 10,6 20,0 9,9 9,3 8,7 8,3 7,9 7,6 7,3
2
f
75 (J
f
m
NI mm~·)
m
1,44 1,58 1,71 1,87 1,83 1,95 2,06 2,16 2,27 2,36 2,46
12,6 11,4 10,6 20,0 9,9 9,3 8,8 8,3 8,0 7,6 7,4
1,54 1,68 1,81 1,97 1,94 2,05 2,16 2,27 2,37 2,47 2,56
(J
N/mm 2 12,4 11,3 10,5 20,0 9,9 9,3 8,8 8,4 8,0 7,7 7,4
1) with 7,03 N/m ice load corresponding to ice load according to (5.28), limitation of maximum tensile stress to 20 N/mm 2 .
5.8 apply. The values given in this Table, calculated according to (5.54), are used in clause 6.11.5 as a basis for proving that railway power supply conductors conform with clearance requirements. The fixed contact wire of a tramway overhead contact line will be used to illustrate how equation (5.54) can be applied. For practical applications, transformation of the equation (5.54) to obtain the required tensile force parameter Hx, yields (5.55) For a tension length with n spans of different lengths li, we can substitute the ideal, or equivalent span length as explained in [5.7] (5.56) Example:
Determine the tensile force acting at -20°C in a trolley-type overhead line section with 10 spans and an equivalent span length of 45 m, comprising an Cu AC-100 contact wire which has been installed with a tensile force of 8 kN at +10°C. According to Tables 5.1 and 2.11: A= 100 mm 2 ; E 124 kN/mm 2 ; cv = 17 · 10- 6 K- 1 ; G~ G'.i: 8,73 N/1tL By inserting these values and the temperat,mPs into equation (5.55) it is obtained:
H~ (HL -
8000
+ 124 000 · 100 · 8,73 2 · 4ti2 / (24 · 8000 2 )
+ 124 000 · 100 · 17 · lO-(i(-20 which reduces to:
Hf (H:i;
13 078 N)
= 71),74 .
1()'
1
N1
10))
= 124 000 · 100 · 8,73 2
·
4C> 2 /24
5.3 Physical state change equations
239
This cubic equation of H:i: can be solved by iteration: H:i: = 14 000 N results in H;, (H:i: 13 078 N) = 180 · 10 9 N:l H:i: 13 500 N results in (H:i: - 13 078 N) = 76,9 · 10 9 N3 H.1: = 13 550 N results in H:z:2 (H:z: -13078 N ) = 86,7 · 109 N·'l H:z, = 13 515 N results in H; (1-l:z: 13 078 N) = 79,8 · 10 9 N3 At -20°C, the tensile force is thus 13 515 N. A rise of temperature to +40°C causes the tensile force to drop to 4452 N. The corresponding sag values arc 0,16 rn at -20°C and 0,50 m at +40°C. The difference is 0,34 m.
H;,
This example illustrates the large tensile force variations occurring in contact ·wires with fixed terminal anchors. The change in tensile force increases with decreasing support span lengths. The overall tensioning section length has no effect on this phenomenon. It is possible to reduce the tensile force variation by incorporating a spring. The extension of a spring is
6.Lcw
= (H:i:
(5.57)
Ho)/ccw
where ccw is the spring constant. The length changes clue to the summation of various factors, such that the total can be expressed as:
Lx
Lo
= 6.Lw + 6.LE + 6.Lcw
By applying (5.48), (5.49), (5.53) and (5.57) a similar formula to the equation of state to (5.55) can be formulated for a tensioning section which is tensioned by a spring n
H; ( (Hx - Ho) (1
+ (E A)/(ccw
L li)) +EA G~
2
l;4 /(24 HJ)+ EA o:(d.1: - do))
i=l 2 = E A G':z: 2 l'eq /?4
(5.58)
~
Example: A spring with spring constant ccw = 10 kN /m is arranged in the tensioning section as described in the preceding example. The tensile force at -20°C is then also calculated using a cubic equation of H 1 : and is found to be 9566 N. For +40°C, the tensile force is found to be 6050 N. It is conclusive that the introduction of a spring reduces the change both in the tensile force and in the sag. In semi-compensated contact lines with fixed catenary wire termination, equation (5.54) is used as the basis for determining the tensile stresses and the sag of the catenar)· wire. According to [5.8], the following applies to the maximum catenary wire sag for a given state :c:
fcA n1ax
l2
•.,,
L7 011L:i:
+ C....,'0HL H.cw /Jc_]'1 CAO 7
Iu the case of ice loads. which are expected at tempe1at11n~s arouud -f>°C ,
+ c;C(:
(5.59) G~rnL:r:
=
rnust lw tak<~ll into consideration. fn ,dl other cases, G\)111 r = G~)IILO - G~:,\ + Gc:w· If li1t1its arc specified for the value fT 1, 1ax, tli<· t<~nsilC' !'off<' ff<:.\ 11 in the catcnary ,vire at stat.<· 0 has Lo IH' determined by G~JIIL
soh·illg Lll<' ,1lim <) <'q11i\tion 1111111<·ri(';ill\-.
240
5 Calculations for overhe;:~d contact line equipment
Figure 5.11: Defiectiou of a staggered contact wire along a straight-line section by the act.ion of wind.
Deflection due to wind
5.4 5.4.1
Deflection due to wind on tangent track
The force exerted by wind on the wires and conductors of an overhead contact line deflects them horizontally, they produce a blow-o_ff. Directly proportional to the wind load, the deflection is inversely proportional to the tensile force on the wires. The acceptable deflection (blow-off) of the contact wire is limited by the operating range of the collector head on the pantograph. The design of the overhead contact line equipment must ensure that the lateral deflection is kept within permitted limits and that the pantograph cannot run off the contact wire - an occurrence also termed dewirement. For conductors with a circular cross section of diameter d, the wind load per unit length is
F~
= (1 / 2)
· 1 · vR, · cw · d
(5.60)
The aerodynarnic drag factor cw is taken from Table 5.7. Similarly to (5.34), the deflection of a single wire by wind, e.g. the contact wire of a trolley-type overhead contact line installation, at a point x to the right of the reference support, as shown in Figure 5.11 is described by
Yw(x)
= F~ · :x: (li
- :x:)/(2 H)
(5.61)
The coordinate system in Figure 5 .11 was chosen to correspond to the definition of a positive lateral offset as being on the right-hand side of the track centre line as viewed in the direction of increasing support numbers. Contact and catenary wires are connected to the supports with alternating lateral offset, called ''stagger". The lateral offset when wind loads act on the system is the result of the superposition of both the factors yw(:x:) and (5.62) The complete equation describing the lateral position is e
(F~ :r / (2 H) + (bi - b.i + 1 ) / (F{vUi :r)/(2 H) + (h1+1
(li :r) + bi+ 1 bi)/li) · .r + bi
/ z) •
(5.63)
By differentiating and equating the differential to zero, the position with the greatest lateral offset cau be found:
5.4 Deflection due to wind _ _ _ __
241
I
I
1/2
contact wire offset ew;(x), wind blowing from inside of curve
/
.¥:---+-----""";;;..,,.....a:::.-+.;.--+--"'------"""''--+¥,_i
+
position of contact wire e 0 w(x) in slill air 1 line connecting two consecutive support locations on track
b, +1 . centre line y11 (x) contact wire offset ewa(x), wind blowing from outside of curve
Figure 5.12: Deflection of contact wire or catenary wire along a curved track.
which means that the maxirnum defl,ection due to wind action is Cmax
(bi - bi+i) 2 . H /(2 F{1y l;) +(bi+ bi+i)/2
= F~ l; /(8 H)
(5.64)
This applies to the case where the wind load per unit length F{v is greater than 2 bi - bi+ 1 I H / l;. If this were not the case, the point with the mathematical maximum deflection due to wind would be outside of the span under consideration. For the case that occurs most frequently in practical applications, where bi - -b and bi+i +b, it applies J
Cmax
= F{A,r t2 /(8 H) + 2 H ti /(F{v 12 )
(5.65)
5.4.2
Deflection due to wind and contact wire stagger 1n curves
5.4.2.1
Contact wire offset in still air
Along curves, the o.ffc;et of the contact wire rnust be calculated relative to the position of the canted (super-elevated) track centre line. In the (:r:, y)-coordinate system shown in Figme 5.12, b has been assigned in such a way that, facing in the direction of increasing chainage, offsets to the right of the centre line are consiclerecl to be positive and offsets to the left, negative. In this coordinate system, the track centre line can be desc-rihrd by the equation //H
(:i:) -
-J R
2
-
(:i: 2
-
li/2) 2 + R
.%
The absolute value of the offset l/I< from a line rnm1rc-ting the track centre line points at the two neighbouring supports i aud z + 1 is calculated by:
(lJ2f-
+ (/?
- //F.)
2
= H2
to IH'
u,, = ll -- ll J1 -- (li/(2 R))2
5 Calculations for overhead contact line equipment
242
As
(ld (2 R)) « '.IJK
1 and Jl - .1: ~ 1 -
J; /2,
which is simplified to:
t;
= /(8 R)
By applying (:r - ld2)/ R following is obtained:
<<
l in '.IJR(x)
=
J1 - (x - ld2) 2/ R 2 )
+R
lU(8 R), the
(5.66) The curve is approximated by a parabola. The error in this approximation for the offset '.IJK is 0,2 % for a curve of radius 180 m and a support spacing of 33,4 m. Taking the stagger bi and bi+I at supports i and i + 1 into consideration, the position of the contact wire in still air in the coordinate system of Figure 5.12 and equation (5.62) is (5.67) The differences in span length in terms of the distance between points on the track centre line and between the length of the contact wire between support points are not taken into account in this case. The contact wire offset relative to the track centre line is calculated as the difference between (5.66) and (5.67):
Ys(x) - YR(.T) (bi+1
bi) x/li
In the middle of a span at li "c-value", is
+ bi -
x (x - li) / (2 R)
(5.68)
= l/2, the lateral position, which is often termed the (5.69)
For the most frequently occurring case, in which bi
= bi+i = -b, this is simplified to
c=l 2 /(8R)-b
(5.70)
where b is to be taken as the absolute value. The c-value is positive for {2 / ( 4 R) > b.
5.4.2.2
Contact wire offset under wind load
When the contact; un:n' o.ff:'wt v:ndff wind load is to be determined, a distinction is made between where the wind blows from inside the curve and where it blows front outside the curve. Similarly, with (5.34) and (5.Gl) the lateral offset of the wir<' whcu subject to a. wind load is expressed by the eq11atio11
(5.71) Tlw positive sign appli<'.s Lo ,viud act.ion from i11sid<'. wind a.ction from outsid<· l Ii<\ n11 V<'..
or Ll1<~
<·11rv<
1
•
t lic
11< g,lt iv<' sign to 1
5.4 Deflection due to wind ___________
243
When the wind blows from outside the curve, the contact wire offset from the track centre line is Ys(.1:) - YR(:r:) - Yw(2:)
ewa
(bi+ 1 - bi) :i: / li
+ bi
-
=
.1: ( :x:
li) · (1/ R
+ F{,.; / H) 2
.
(5. 72)
To determine the position at which the maximum lateral offset occurs, the state dewa(x)/dx = 0 is considered:
(5. 73) This leads to the following equation for the maximum lateral offset of the contact wire under wind load:
As R approaches oo, equation (5.74) is transformed into (5.64) and for the most frequent practical cases where bi= bi+I = -b, equation (5.74) results in
(5.75) When the wind blows from inside the curve, the contact wire offset from the track centre line is
+ Yw(.1:) = bi) x/li + bi - x(x
Ys(:x:) - YR(:x:)
(bi+1 -
li) · (1/ R - F{,.;/ H)2
(5.76)
Here too, the position at which the ma.1.:imum lateral o.ffset occurs is determined as
(5. 77) which then leads to the following equation for the maximum lateral offset of the contact wire under wind load:
For the case bi - b;+ 1 ewi,max
5.4.3
(1/ R
-
-b, and taking the sign into consideration, it follows that
F{v / H) t2 /8 - b .
(5. 79)
Deflection of overhead contact line equip1nent due to wind
If the equations (5.G l), (5 . G5), (5.G7) and (5.G8) are applied indiYiclually to the catenary ,.vin\ or contact wire, different. lateral offsets axP obtained for the effects of differing ,vind and t(\11sile forces . When the catenary wire and the cor1tac-t wire are deflected 0
differently by wind a('tion, they (~xert force components upon <'ach othn because they arc connect.eel via tli<' dropp<~rs.
5 Calculations for overhead contact line equipment
----,
catenary wire at the support catenary wire, deflected by wind, at the middle
Y wind load on overheadijcontact line equipme~t
PW,CWCA
SH wind force on;=;> overhead contact line equipment
track centre line
"
I
I \
I I
contact wire, I deflected by wind, FW,CWCA ~~_. at the middle I re ~f the span l-·1 I ecw ,rack centre line
ecw
e
CA
catenary wire \
,,,-,·
F, / , W.CWCA,,'
\
',
,,
I /2
X
Figure 5.13: Slanted deflection of the Figure 5.14: Force coupling component acting overhead contact line equipment in cases through the dropper between the contact wire and where the contact wire is deflected for- the catenary wire under wind load F~ CWCA· ' ther than the catenary wire and the droppers transmit coupling forces onto the catenary wire.
The method applied up to nmv in practical calculations ignored this fact and calculation of wind defiection of an overhead contact line equipment was based on the assumption that the entire overhead contact line equipment is deflected by the same offset when exposed to wind loads. The force exerted by the wind was calculated for the complete overhead contact line equipment. It was used in the respecti\·e formulae and the sum of the tensile forces on the catenary and contact wire was taken to be the tensile force (cf. equations (5.67) and (5.71)). Depending on the real parameters and conditions, this method leads to offset value results that could be either lower or higher than the real values If the contact wire and the catenar:· wire assume different offsets under wind load, the droppers are pulled into a slanted position and transmit a part of the wind load to the element experiencing a lower deflection. In the following text, a method based on [5.9] is described, in which it is assumed that interaction \·ia the droppers occurs between contact and catenary wires along the entire length of the span. The forces acting bet\\'een the contact wire and the catenary \\·ire due to the action of the wind are linear fqrce distributions, that is, forces per unit length which are assigned the designation F{u·wcA . As an approximation, it is assumed that the dropper lengths along the span are all equal to a specific average. This rrwans, as can be seen in Figure 5.13, that all droppers in this span have the same deflection angle to a line plane perpendicular to the track. This assumption is permissible for system heights greater than 1,4 m. A parabolic function is assumed to describe the horizontal deflection of the catenary wire clue to the force per uuit ](\11gth F{v,r:wcA (~xened b,· the contact wire. Expressed
5.4 Deflection clue to wind _ __
245
in relation to the half-span shown in Figure 5. U, this is Y
= Fw,cwcA :r: 2/ (2 H) c
I
( 5.80)
To calculate the complete deflection of the catenar~' wire and the ecmtact wire due to wind loads, the following loads per unit length must be taken into account catenary wire , FWC/\,tot (5.81) = F''WC/\ + F'W,CWC/\ contact wire F{vcw,tot = F{vcw - F{v,cwcA (5.82) In these discussions, it has been assumed that if the tensile forces on the catena.ry wire and on the contact wire are equal, the contact wire will be deflected further than the catenary wire because the former has a larger diameter. In such cases, the catenary wire reduces the deflection of the contact wire by wind. In equation (5.80) the contact wire stagger has not been taken into account. The difference in the lateral offset due to the different deflections of the contact wire and catenary wire at the middle of the span is assigned the term 6e It is calculated by:
6e
= ecw - ecA
(F{vcw - F{v,cwcA) l
8Hcw
2
( F{vcA + F~v ,cwcA) l
2
8HcA
(5.83)
Furthermore, from Figure 5.13, the following can be obtained: 6e/(2 SH/3)
= F'{v ' cwcA/G~w
where SH is the system height. This can be resolved to give 6e 6e
2F{v,cwcASH/(3G~w)
(5.84)
By equating (5.83) to (5.84), the equation is obtained describing the length-related
force coupling between contact wire and catenary wfr·e under ·wind loads: F'
_
F{vr HcA F{vT Hew w,cwcA - Hew+ HcA + (lGHcwHcA SH)/(3l2G'cw)
( 5.85)
An accurate and realistic calculation of overhead contact line equipment deflection is possible with computer programs that use Finite Elem.ent Analysis (FEA). The application of FEA to this problem is demonstrated using several examples. Figure 5.15 shows the relative positions of the contact wire and catenary wire of a standa.rd overhead contact line equipment He 200 with a support span of 80 m as detennined using FEA. Examples:
Determirw the wind deflection of the contact wire aud the cateuary wire of the standard overhead contact line equipments Re 200 and Re 3:30 used by the DB. The specifications of the Re200 design are: G~:,,· 8,73 N/m, Hew = He,\ = 10 kN, b1 = -b-i.+ 1 0,4 m. For vw 26 m/s and taking iuto account the wind loads on the dips, clamps and droppers according to Table 5.7, is obtained F{v 0111 = 11,5 N/rn. The individual components derived a.re F{vcw = 6,5 N/m and F{vc, = 5,0 N/m. The span bdwct,u supports is l = 80 m.
5 Calculations_ for overhead contact line equipment
246
------------
- catenary wire
contact wire
-Figure 5.15: DB standard overhead contact line equipment Re 200 subjected to wind load, results of a Finite Element Analysis.
Table of results, examples: Deflection of overhead contact line equipment types Re 200 and Re 330 clue to wind, as calculated by conventional approximations, by finite element analysis and by applying equation 5.85, all values given in metres. without dimension b Approximation FEA (5.85)
Design
Component
Re200
contact wire catenary wire contact line equipment
0,520 0,400
contact wire catenary wire contact line equipment
0,268 0,345
Re330
0,481 0,437
0,488 0,432
0,460
0,302
with dimension b Approximation FEA (5.85) 0,597 0,400
0,570 0,450
0,570 0,434
0,363 0,406
0,358 0,402
0,547 0,282 0,342
0,277 0,335
0,352 0,410 0,369
The calculation is carried out using the coupling force F~,CWCA in accordance with equation (5.85) with and without taking the dimension b into consideration. The results of the calculation are shown in the table of results for this example. The deflection of a DB standard overhead contact line equipment Re 330 by wind was calculated using following specifications: G'cw = 10,48 N/m, Hew 27 kN, HcA 21 kN, vw = 37 m/s and the corresponding values in Table 5. 7 F~cw = F{vcA = 13,7 N/m, bi= -bi+I 0,3 n1. For F{vmIL a value of 27,4 N/m is assumed; l = 65 m. The results are also shown in tlw table. It can be seen that the results obtained using (5.85) correlate well with the results obt,;i,ined by applying the finite element analysis.
The Re 200 example illustrat<\s that if the deflection of contact wire alone b? wind is taken into account, tlw ddl<~ction values ("alculated are larger than those obtained if the complete overhead co!lt ,1ct lit1<' ('
5.5 Longitudinal_spans and tensioning sect;ionlengt.hs
247
having less effect 011 a cateuary wire thau on a contact wire subjected to the same tensile force. The results of fiuite element analysis and the results obtained using the approximation according to equation (5.85) coincide closely. The Re 330 example also shows a good correlation of the values obtained by FEA to those obtained according to equation (5.85). In this case, calculating the winddependent deflection of the contact wire alone, leads to low deflection values. This is because the tensile force on the catenary wire is lower than on the contact wire, ,,·hile both are exposed to the same wind load. In the table of results obtained for these two examples, the values are given with an accuracy of three decimal places in order to show the differences between the individual methods discussed here. In practical applications, two decimal places are sufficient because of the large number of assumptions made.
5.5 5.5.1
Longitudinal lengths
spans
and
tensioning
section
Relevance of span and tension lengths
Longitudinal span lengths and tensioning section lengths have a considerable effect on the investment cost of overhead contact line installations. At the sr1me time, they also affect the quality parameters such as uniformity of elasticity and contact force performance. When planning overhead contact line installations, the use of the longest possible span lengths and tensioning sections is the most effective way of reducing costs.
5.5.2
Maxi1nun1 possible spans
5.5.2.1
Significant parameters
So far as the geometrica.l interactions are concerned, the rna;cim'um poss1,ble span length is the distance between two supports where it is certain that the contact wire will not move out of the range of operation of the collector strips on the pantograph, after considering the anticipated Yehicle motion and the effect of given wind conditions. Using this definition, the maximum possible span length depends on: the operc:.~ing range of the pantograph collector head, the wind speed assumed when designing the system, the lateral displacem,ent of the pantograph at the point of c011Lact at operating height, and on the overhead contact line type, especially on the tensile forcc~s acting on the contact ,vire and the catenary wire. The parameters ,vind speed and overhead contact line type, incorporating parameters such as wire dia111eter and tensile forces, have been discussed in the pn~ceding clauses. In the follcl\ving sections, th<' vehicle-rdated effects on permissihl<' longitudinal span l<\ngths of ovm-lwad cont.art line installations are amtlysed.
248
5.5.2.2
_ _ _ _ _ 5 Cal_£t1lations for overhead contact line equipment
Working range of pantograph head
The pantograph head working range that ensures a safe contact between the collector strips and the contact wire, in accordance with Figure 2.16, is determined by the design of the pantograph head. This is accepted as being larger than the length of the collector strips because it is assumed that the contact wire rarely runs outside the collector strips right up to the limit of the working range. For example, the DB standard pantograph head used for speeds up to 280 km/h is 1950 mm wide. The pantograph head working range is 1450 mm a,nd the collector strip length is 1030 mm. When discussing the geometrical interaction between contact line and pantograph, the lateral movement of the vehicle and its effects on the pantograph position must also be considered. There are two basic conditions to be assessed: The first condition refers to still air. In this condition the geometric contact wire position without wind load as expressed by the stagger at the supports and the offset at mid span should not leave the collector strips. The sway of the vehicles must also be considered. In the second condition, the action of the maximum design wind is assumed in addition to the aspects of the first condition. Under this condition the contact wire may use the pantograph beyond the collector strips and defined as working range. Parameters, especially span lengths, have to be selected such that these conditions are met. However, it should be noted that in the case of contact lines for train speeds above 230 km/h, it might be necessary to limit the span lengths to achieve a target elasticity and improve the dynamic interaction between pantograph and contact line (see clause 9.5.5.2). 5.5.2.3
Lateral movement of the vehicle
The effect of the lateral movement of the vehicle at the collector's working height depends on contact wire height and collector working height. the rolling coefficient and rolling height at the collector interface. the geometry and characteristics of the wheel sets and of the bogies, the height of the pantograph knuckle and the pantograph flexibility and structral tolerances, the track gauge, curve radius, cant deficiency, the lateral track shift and deficiency in cross level and tolerances. In particular, the lateral displacement of the collector head at its operating height is a specific characteristic of the vehicle. All DB overhead contact line installations for running speeds of up to 200 km/h are designed to allow kinematic displacements of the centre of the collector relative to the track centre line, as shown in Figure 5.16. For highspeed rail traffic, it is desirable to design the overhead contact lines to accommodate vehicles which are standardized throughout Europe. In this case, conformance with the limits of the indiviclua,I parameters in accordance with UIC code 606-1 is required. Figure 5.17 shows the relatio11ship betwee11 the kinematic displacement of the collector
5.5 Longitudinal spans and tensioning section lengths _
249
350 - , - - , - - - - , - - , - - - - - - , - - - - , - - - - , - - - r - - - , - - - - , - - - , - - - - - , - - - - - . - - - - - , - - - - - ~
mm
400
500
600
700750
1000
1500
2000
2500
m
3000
Radius R - - - - - - - -
Figure 5.16: Lateral offset of the collector head used by the Deutsche Bahn as a basis for calculating the limits of the contact wire positions, for a contact wire height of 5,30 m, as a function of the curve radius. a) 450
mm
1iJ
1---
.c
0
o ..
350
0(.) (1)
:S 300 0 ill (/)
'§ 250 cii
.
~
~
---1--r I
I
·
,__ ICT a(q)=2 I I
------
in accordance with EBO reference Jehicle
-- -
- --==
--- -
-AC:::::
i:::--
---1-
K""icT, a(q) 1 _
\
-
ai
j
i-
I---
(1)
-- ---:.--
-- -
400
~
-
" ICE 1
BR11°
200
5
5,2
5,6
5,4
5,8
m
6,2
6
6,5
Contact wire height b)
450
I
mm
1ila,
400
.c
0
0 ..
:5
350
I--300
0
ro
'§
-
250
cii
-
--
I---
1---i - -
-
- --
-
I---
--
-
I - - -I - - -
i - -i - -
--
-
ICT a(q)=2
1-
/
I
l,_.£--
- --
reference vehicle
I---
~
/ICT, a(q)=1
-
"'-
ai
j
- -"'ICE 1
200
5
5,2
5,4
5,6
5,8
6
6,2
m
6,5
Contact wire height
Figure 5.17: Lateral offset of the collector head of selected vehicles for R R 1000 m (b) as a function of the contact wire height.
= 250 m (a) and
5 Calculations for overhead contact line equipment
250
mm
8zu/
400+---r--,--,---,------i-~~~-r----+ 100 500 1000
1000
2000
m
3000
R
Figure 5.18: Limit positions of the contact wire with deflection by wind, as specified by the DB. a) limit position in accordance with No. 9 Ebs 02.05.06 b) limit position determined from Figure 5.17, track fixed laterally c) limit position determined from Figure 5.17, track not fixed laterally
centre of various vehicles and the contact wire height for curve radii of 250 m and 1000 m. The vehicles indicated by the abbreviation ICT are equipped with automatic in-curve tilting mechanisms.
5.5.2.4
Contact wire limit position with deflection by wind
By subtracting the kinematic displacement/of the centre of the pantograph head from its working range, a range is obtained within which the contact wire may be positioned. In Figure 5.19, the permissible contact wire limit positions including wind deflection, combine the interaction of the operating range of the pantograph head and the kinematic displacement, for both maximum speed and low speeds, about the centre of the pantograph head relative to the plane through the centre of the line connecting the railheads and perpendicular to this line, (also known as the canted track centre line). The limit position on the inside of the curve is deduced from the working range limits at maximum speed and the limit position on the outside of the curve from the working range limits at low speeds. Relative to the track centre line and with a collector head operating width of 1450 mm, the contact wire position limit at the outside of the curve for wind loads is 725 mm. For the inside of the curve, the contact wire limit position is deduced, as shown in Figure 5.19, from the track radius-dependent collector head position limits according to Figure !i. 18 and the value 725 mm, which is half the collector
5.5 Longitudi11al_spa11s and tensiouiug_ section leugths
251
Section A-A
r- /a ?±~--. I
I
I
a3
-~-f
(1)
C
I
;1 ~I
(.)
TI/ ~I
I
contact wire (position at still air) contact wire (deflected by wind)
-~
Figure 5.19: Determination of the permitted contact wire limit positions, with and without wind action.
a1 a2
a3 d e f
limit position with wiud action limit position in still air operating range of collector head at maximum speed operating range of collector head at low speeds range of permitted contact wire position with wind load collector head position at maximum speed collector head position at low speeds lateral offset of the collector head at maximum speed
head working range. In still air, the contact wire should interface with the pantograph head in the range of the collector strips. On standard pantograph designs used bv the DB, the collector strips are 1030 mm long. Because of this, the stagger at the supports is limited to ±400 mm. It is not possible to fully exploit the maximum offset at the supports that is theoretically possible with the whole working range of the pantograph head. On the outside of the curve, contact wire positions up to 515 mm are permissible, on the inside of the curve, the track radius-dependent values are permitted as shown in Figure 5.18 which have !wen derived from the lateral pantograph sway in accordance with Figure 5.17. The track radius-dependent position limits for the contact wire, shown in Figure 5.18, are applied when planning overhead contact line installations for DB. The data in Figure 5.18 is based on DB standard 9 Ebs 02.05.06. The offsc~t corresponds only to the \Vind deflection of the rnntact wire if the contact wire is 011 th<~ track centre line at
5 Calculations for overhead contact line equipment
252
the centre of the span, that is, the distance of the contact wire from the track centre line at this point, the c-value equals zero. In other cases, the contact wire position limit is the sum of the c-value and the deflection due to wind. Figure 5.19 indicates how these factors are related. The SNCF specifies a uniform limit position of 350 mm for all curve radii. This is to accommodate pantograph heads with shorter effective widths than on DB. 5.5.2.5
Determination of longitudinal span lengths
Conductor displacement due to wind is the decisive overhead contact line factor governing longitudinal span lengths. If the permitted contact wire position limits with wind action are known, the equations shown in clause 5.4 can be used as a basis for calculating maximum possible longitudinal spans. For straight track, the maximum possible longitudinal span length is derived using the designations in accordance with Figure 5.11 and equation (5.64) with bi = b1 und bi+I = -b2 to give: 2
=
~ (2 eper -
+ b2 + V(2 eper -
+ b2) 2 -
+ b2) 2 )
(5.86) Fw In practice, this equation, which applies to the contact wire alone, can be extended to the contact line equipment. In this case lmax
b1
b1
(b1
Hmr1 =Hew+ HcA is used in place of H and
F~om,
= Ffwcw + F~cA
in place of F{v- Whether or not this approximation is acceptable depends on the ratio of the contact wire deflection by wind to the catenary wire deflection by wind. If a more accurate calculation of the maximum permissible span is desired, the mechanical interaction (by droppers) of the catenary and the contact wire must be taken into account as described in clause 5.4.3. For the case that the dimensions b are all equal, i.e. b1 = b2 = b, as used in practical applications, (5.86) can be simplified to: lmax
=2
: , (eper
w
+ Je~er
-
2
(5.87)
b )
Example: What is the maximum longitudinal span that can be used for a DB standard overhead contact line installation for running speeds of up to 200 km/h? From Figure 5.18, the position limit value eper = 0,55 m and the wind load per unit length is 11,5 N/m from Table 5.7. The horizontal tensile forces on the catenary wire and on the contact wire are 10 kN each. For the offset b value of 0,4 m lrnax
V
)
N · m ( 0 55 111 +o 55 2 m 2 - 0 42 m 2 = 80 3 m = 2 20000 11,5 N ,<
'
<
'
'
5.5 Lougitudiual spans and tensiouing section lm1gths
-------------
- - - -253 -
In the case of an 8 % reduction of the tensile forces near the mid-point support, a maximum span length, i. e. support spacing of 77,l m would IH\ permissible, if the reduction is 11 %, the maximum permissible support spacing would b(~ 75,8 111. As illustrated in Figure~ 5.12, the maximum possible longitudinal span length in a curve depends 011 wllC't.llC'r the wind blows from inside the rnrvc or out.side the curve. For practical applications, only the case where the wind blows from outside the curve is of significance. If e - eper is inserted in equation (5.75), the equation for the maximum possible longitudinal span length in a curve is
lmax
=
8 ( eper
+ b)
F'
/ ( ;;
+
1)
(5.88)
fl
Example: What is the maximum longitudinal span that. can be used for a D13 standard overhead contact line for running speeds up to 200 km/h 011 a curve of radius 250 m? For this calculation, a reduction in the tensile force by 8 % must be taken into account at the mid-point support, i. e. the tensile force is 20 kN 1,6 kN = 18,4 kN. In accorcla11ce with Table 5.7, the wind load per unit length is 11,5 N/rn. In accordance with Figure 5.19, for b = 0,4 m and Cpcr = 0,47 m lmax
=
8 (0,47 m
+ 0,4 m)
11,5N/m ---/ ( 18400N
+ -1- ) = 38,8 rn. 250m
If the offset values b at consecutive supports along the curve are not equal and the values bi = b1 and bi+I - b2 are applied to Figure 5.12 or equation (5.74), it can be shown that an equation for determining the maximum longitudinal span length can also be applied to contact line systems, provided that the substitutions (5.81) and (5.82) are applicable to the case. The following equation, first described in [5.5], applies in cases where the wind blows from outside the curve:
l,nax ==
(5.89)
Table 5.9 contains values describing the relationship between longitudinal span length and curve radii as specified by the DB and by the SNCF.
5.5.3
Calculating tensioning section lengths ( tension lengths)
The standard EN 50 119 calls this parauwter the "tensum lenqth" and ddincs it as the "length of conductor between two anchoring points". Gcncrnlly, hovvcver, a contact wire or contact line <)quipirwnt is tensioned by pulling it away ill both clir<'ctious from an anchoring point located roughly at. tit<' centre of a L<\llsionit1g sect.ion.- Ju order to lw abk to describe t!H' physical problems invol\"<'d, the section hct.m'
254
_ _ _ _5_Calculatl_ons foroverhead contact line equipment
Table 5.9: Relationship of longitudinal span length to the curve radius, as specified by DB and the SNCF.
Radius
Longitudinal span length
m
2:
2000
1800 1600 1500 1400 1350 1300
1200 1100
1050 1000 900
850 800 700 650 600 500 400 300 2.50
180
Ill
DB
SNCF
80,0 79,8
63,0 63,0
77,5 76,2 74,7
58,5 73,2 71,6 69,7
54,0 67,7 65,1
49,5 62,5 59,8
45,0 56,1 52,4 47,9
40,5
42,5
31,5
36,0
38,6 33,4
Tension lengths affect the installation investments. The number of overlaps decreases with increasing tension lengths, which means that installation investments decrease accordingly. Use of the longest tension lengths possible without forfeiting conformity with the specified quality parameters is one of the main goals in designing an overhead contact line installation. The tension lengths that can be achieved depend on a large number of factors as discussed in clause 4.1.10. The main factors are: the working range of the tensioning equipment; the variations in the horizontal tensile forces acting on the wires due to the reaction forces and also acting on the number of spans in a half tension length, the stagger and the distance between the pole and the track centre line; the operating tensile stress that can be achieved, depending on the tensile strength of the conductor material; the variation of the lateral offset or stagger of the contact wire at the supports due to thermal expansion and contraction of the conductors, whereby the cantilever lengths and the nominal temperature also have an effect; the curve radii; · given, i.e. expected, wind speed; o\·erhead contact line teuqwrature range, as well as mechanica.l design of the tensioning mechanisms. Clause 6.5 contains fnrtlwr disc-11ssious co11cerning the choice of tension lengths.
5.6 Referenc;~c;
5.6
____2c.__5,5
References
5.1 KieBli11g, F.; Seumw, M.; Tess1111, H; Zweig, IJ.-W.: Nell(: Hochleistungsoberleitung Bauart Re 330 der Deutschen Balm (The new high-perfonrnuice overhead contact line type Re 220 of German Railway). In: Elcktrischc Dahncn 92(1094)8, pp. 234 to 240. 5.2 Bausch, J.; KieBli11g, F.; Semra11, ]\II.: Hochfostcr Fahrdraht ;n1s Kupfer-Magncsiumlegierungen (High-strength contact wire made of copper magnesium alloys). In: Elcktrische Bahnen 92(1994)11, pp. 295 to 300. 5.3 Gourdon, Ch.: Die TGV-Oberleitungsanlage der SNCF (The TGV overhead contact line of SNCF). In: Elektrische Bahnen 88(1990)7, pp. 285 to 290. 5.4 Siiberkriib, M.: Teclmik der Bahustromleitungen (Technology of overhead contact, lines). Verlag Wilhelm Ernst & Sohn, Berlin/Miinchen, 1971. 5.5 Naderer, G.: Die Fahrleitung, Bauweise und Speiseleitungen (The overhead contact line, design and feeder lines). In: Elektrische Bahnen 11(1935), pp. 65 to 75 and pp. 112 to 117. 5.6 Krumpolt, J.: Optirnierung von Oberleitungsanlagen elektrischer Balmen (Optimizing of overhead contact lines for electrical railways). Diploma thesis. TU Dresden, Institut Elektrische Bahnen, 1996. 5.7 Fischer, R.; KieBling, F.: Freileitungen, Planung, Berechnung, Ausfiihrung (Overhead power lines, planning, analysis and design). 4th edition, Springer-Verlag, Berlin, Heidelberg, New York 1993. 5.8 VEM handbook: Energieversorgung elektrischer Bahnen (Power supply of electrical railways). Verlag Technik, Berlin, 1975. 5.9 Wfassow, I. I.: Fahrleitungsnetz (Overhead contact line network). Fachbuchverlag, Leipzig, 1955.
256
5 Calculations foroverhead contact line equipment
--------
6 Planr1ing of overhead contact line systems 6.1
Objective and process
The objective of the pla:n:11:ing task is to create planning documentation for a specific electrification project based 011 specified conditions, such as technical requirements, line parameters and customer requirements. These documents permit the erection and operation of an overhead contact line system to ddined operational specifications for a specific line. The ovethcad contact line system planning process consists of the following phases: preliminary design study, design planning, project implementation planning, preparation of review documents. The overhead contact line system forms part of the planning work for new lines or reconstrnctio11 or electrification of existing lines. The design study exami11es various options for the overhead contact line system and also identifies any additional infrastructure works required on features such as track layout, tunnelt>, lJridges, etc. The compatibility of the electrification with other technical equipment such as signalling, is also examined during this phase. The prelim,inar:IJ de.<;·i,gn .study produces technical solutions, including the design of the overhead contact. line system, adaptation of the track layout, strnctural alterations to tunnels and bridges, and an estirnate of the irnplementnt.ion time and investments. A summary report of the design study is tlwn provided to railway companies for incorporation into their overall planning. Design pla11:nin.1J commences with the preparation of an overlwad contact line system circuit diagram based on data provided in the prdiminar_v design study (Figure G.l). It contains the feeders, circuit groups, insulated st1bscctions, discomiectors ( electrical switd1es) and traction power lines. The next stage is identification of rot1te constraints that irnpact upon tech11ical aspects of the overhead cont.ad, wiring. This is based on track layout, bridge structure, tumwl, sig1mlling and tclecornrn1rnicatiot1 system doc-u111cutctLio11. Tlw wrn:n,g at these constraint strnct.11res is also ddined dt1ring this early phclS<' Tlw wiring of the int<)rmcdiatc sections is ddirwd dming the tl('Xt stage. Suppor( ing equip111<'nL such as singlt) track caut.ilcv<'rs. 1rntlti-t.ra.ck nrntilcvt)ts, h<'ad span st.rnd11res or porLlls, ar<' assigned Lo tlw OV<'rlt<'ad cotit.acl. line system s11pport points. Tit<· pole locations are assigned 011 t.lw h,,sis of Litt· sp<'cificatio11s and local rnnditions. Tit<' d<)sig11 stt1d_,, including all planuiug doc11t11<'11Ls, pol<' locations and ovrT!inul con/,11.cl l111c sysf/'.lll lr11;o·u,/ di,\grarn, is th<'II disl1ilH1tt•d \\'itli n11 <'xplrn1a(on report to all i11Lnt•stt•d p,1rt.i('s for co111nH~11L \ sil(' i11~,i)('c(io11 ()r Ill<' li11<' !iv ,di projt'ct pi11licip;i11ts is tll(' lirsl pl1;1s<' of 11rojr:I'.!
258
-------·-··-···-·····---------
6 Planning of overhead cont.act line systems
Design planning Prepare overhead contact line system circuit diagram
I
Identification of constraints such as points, sub-sectioning, structures, railway crossings, etc
D
Preparation of the wiring design wilh the mast locations al constraints
D Preparation of the wiring design with the mast locations in between constraints
Explanatory report, overhead contact line system layout plan
~-D--Project implementation planning.
Figure 6.1: Design planning process.
implementation planning for the electrification of existing lines. This inspection assists
with the identification of all installations that may clash ·with planned pole locations. Items to be considered include underground services, culverts, drains, permanent way profile, signal visibility and neighbouring buildings. A report is made of all information gathered during the inspection and conclusions drawn for planning of the overhead contact line system. For new lines, the design plan is agreed and confirmed, at a joint meeting, by all project participants. The departments responsible for planning of track, civil engineering, bridge works, tunnelling, signalling, telecommunications, 50 Hz power supply, point heating equipment, substations and disconnector remote control systems must take into account all proposed pole locations during their subsequent work. After fixing the pole locations along and across the track, a transverse profile survey is carried out at each pole location in order to establish foundation requirements and pole lengths. Detailed verification is required that adequate clearance exists between live parts of the m·erhead contact line system and other assets. Pole locations and lengths must be assigned in such a manner that the required minimum clearances are provided. After the owrhead contact line system layout has been determined, the materials are selected frorn a set of standard drawings for the chosen overhead contact line system design and in accordance with static load calculations. 1\Iaterial selection and the calculation work are simplified by the combination of standardised components into standard modules. A \·iable project must ha\T(~ a prn7ect implementatum, plan, which includes the following: (1) An e:rplan
civil engineering aspects of the' proj<~ct,
G.l Objecti\lc alld process
259
Approval of the design study by the respective customer entities
D Projecl implementation planning Agreement of the overhead contact line system layout with all specialists participating in the planning by means of a joint inspection on foot or by discussion
D
I Internal review
D
SuNeyof transverse profiles
D Fil foundation to transverse profile, determination of pole length and verification of clearances
I I
Subsoil investigation
D Design of foundations
r-'\
D
I Static analysis I D Iquantity Material and I determination
'-,/
Project documents: Explanatory report, overhead contact line system layout plan, circuit diagram, earthing plan, overhead contact line system adjustment plan, cable location plan for pole disconnector remote control system, transverse profile plan, longitudinal profile, overhead contact line system height reduction plan, project specific structures with drawings and calculations, polygon calculations for head-span structures, complete material lisL
D Checking and approval for construction by the customer
D Material procurement
D ( Start of construction )
Figure 6.2: Project implementation planning process.
(2) Overhead contact line system layov,t plans to a standard scale 1: 1000 or 1:500, (3) Tra:nsverse profiles for opcu track and stations, (4) Longitwlznal profiles for 11011-olivious routing of traction power lines, (5) Longi{'U,dinal profiles for overhead contact line system, he'i,11ht ncdu.clum.s, (G) Prn_jed-spcc,Ufr s/,r1u:/u:res wit.It d1awi11gs aud calculations, (7) Ca:ntilevr:r- aud droJJJH'.l frn,r1th 1:11Jt·11,lations, (8) Polyyon calnda/um.., for h<'ad-spau structures, (9) Ea:rthznq plu:n.., for st.a lions, ( 10) Cahle layout JJlm1.s for the control cables of disc:on1wdor remote• control system, ( 11) Cmnp/e/,e J)(J.T/,,, list. cottsisti ttg of' polr: and fou:ndatum. tables, ovcrlu·o,d wn/,11,ct line syste'f/1, to.hi!' aud ,1 !isl of ol li<'r rnat.criaL _:\11 i11t.crnal r<'\'i<'\\' pruc<·ss (Jr i11l<·rnt<'.diat.<· and fi11al results dt11i11g p1oj<'cl itllplemenlnt.i011 plalll1iu,t2, ,m>ids <·rrms ;111<1 lit11s addit.io1rnl costs and li111<' d<·L1\,; \[ntcrial pm-
!. Pl,~nning, of overhead contact line systems
260
curement and construction work commences after checking and approval of the project by the customer. The process of project implementation planning is illustrated in Figure 6.2. In order to shorten the project implementation schedule it becomes necessary to approve parts of the documentation before all documents are completed. This particularly applies to the civil engineering portion of work relating to poles and foundations and includes parts (1), (2), (3) above and the pole and foundation tables from (11). Construction supervision ensures that implementation is carried out according to the design. Where obstacles arise, necessary deviations are implemented after agreement with the project engineer and other affected parties. Variations from the implementation plan, which arise during the course of the construction work, are to be carefully and continuously recorded in the project documentation. After completion of the work, the revised documents will give an accurate picture of the installed overhead contact line system. These documents provide the system operator with the basis for operations management and maintenance.
6.2 6.2.1
Fundamentals and initial data General
Overhead contact line system planning and construction work are based either on the standard specifications for a specific design of overhead contact line system or on functional specifications. The latter provide the contractor with the flexibility to develop an overhead contact line system that is tailored to the project. Both variants require the compilation of planning data that represents the technical reqv,irements. This data set serves as an initial guide for all those involved in the project and ensures a rapid and correct planning process.
6.2.2
Technical require1nents
The technical requ'irernents are listed in a data summary. The data summary presented in Table 6.1 includes the planning parameters of DB standard overhead contact line system design Re 200 as an example.
6.2.3
Planning documents
6.2.3.1
Introduction
The plannuu; doc:·11:111,ents represent the line, whether newly installed or existing. They form the basis for the design of the overhead contact line system and include information relating to existing installations and the topography. Document form and contents vary for new, existing and pre-electrified lines that are to be modified. These variants arc~ treated sepa.rat<'I\' lwlow.
------ _ _ _ _ _ __:2::c:6c:c:l
Table 6.1: Example of technical requirements fr)r the DB, He 200 standard design.
Technical requirements General data Rated voltage in kV / frequency in Hz Traction power supply system Speed on main lines / secondary liues Desigu for maiu lines / :;econdary line:; Pantograph Static: cont.act pre:;sure minimum / maximum in N Dynamic contact pressure minimum / maximum iu N Coutiuuous cunent carrying capacity without parallel feeder at °C / A Line information Position of the line (e - exclusively, i - iuc:lusively) Gauge in mm Specification for gauge Line length in km Number of tracks Minimum track curve radius in rn Climatic information Ambient temperature (average value of the annual extremes) in °C Temperature workiug range of the overhead tontact line system in °C Temperatme for the central position of the cantilevers in °C Average relative humidity in % Climatic: zone (coastal or inland) Environmental pollution by industrial areas yes / no Altitude H of the line above sea level in m Wind speed vw in m/s Construction tolerances Distance between top of rail and top of foundation or pile ('e' dimeusion) in mm Distance between track centre and pole front face ('TP' dimension) in mm System height SH in mm Contact wire stagger at :;teady arm with no wind in m1t1 Contact wire height at support in nun Contact wire gradient d1ange Constant-tension section length in Ill
Re200 15 / 16,7 central 200 / 100 Re 200 / Re 160 UIC 608 Appendix 4a or b 60 / 90 40 / 200 70 / 560 A-to\\n (i) - B-town (e) 1435 DS 800 01
63 2 900
15 / +37 -30 / +70 +20 max. 50 inland 110
0 < H < 50 26
±30 50 ±30 ±30 ±10 < 1 1000 ±1
6 P~anning_of overhead contact line
Technical information for overhead contact line system Contact wire type / tensile force in kN / max. wear in % Catenary wire type / tensile force in kN / fixed termination or automatically tensioned Stitch wire provided / type / tensile force in kN / length in m Dropper type Tensioning of contact and catenary wire, separate!_\· or jointly Transmission ratio of tensioning device Maximum half tensioning length in m Reduction of tensioning length in curves / specification Maximum / minimum span length l in m Determination of span length l in dependence on radius R or on the wind speed vw Contact wire pre-sag fp in m Maximum contact wire gradient at overhead contact wire height reductions Maximum gradient in transition spans Standard contact wire height CWH / minimum contact wire height CWHmin/ maximum contact wire height C\VHmax in m System height SH on open track / in station in 111 Minimum clearance catenary wire to contact wire in mid span in m Contact wire lateral displacement (stagger) at supports on straight track / in curves in m Maximum permissible displacement under wind action (eperm) in m Cate nary wire lateral displacement (stagger) in m Dynamic uplift at support as quasi-dynamic uplift in rn Use of windstays Power frequency flashover voltage in kV (50 Hz dry) Creepage path for insulators at terminations / intermediate insulation / cantilever insulation in mm Distance between the contact wires in overlaps in mm Number of overlapping spans Tensioning weights concrete / steel Use of neutral sections Length of neutral sections Point wiring: crossing or tangential Lines Feeder line, aerial Feeder line, underground Bypass line Parallel feeder line Switch line Return conclnctor type / aerial or underground conductor / insulatPd or not insulated Insulators Insulator for anchor, switch lines a!ld illtm1twdiate illsulation typ<) / material Cantilever insulator t.VPP / matl~rial Hazards, 11on11al/ Yandalis1n-enda11g<'n~rl
1) Ebs. Design sta!ldard for DB's o, <'t ltr)ad coll tact lin<•s
Cu AC-100 / 10 / 20 Bz II 50 / 10 / automatic yes/BzII 25/1.8-2.3/14-18 Bz II 10 separately 1:3 750 m yes / Ebsl} 80 I 33.4 l
= f(R)
in accordance with Ebs 1:500 1:800 5.5 / 4.95 / 6.5 1.8 / 2.0 0.5
± 0,4 / 9 Ebs 02.05.06 0,55 as contact wire Ebs R> 1200 m 110 485 / 485 / 485 450 3 or 5 concrete no crossing EN 50182, 243-ALl N2XS2Y EN 50 182, 243-ALl Cu 95 EN 50 182, 243-ALl / aerial conductor / not insulated
Ebs 02 . 05.15 / porcelain Ebs 02.05.15 / porcelaill normal
6.2 Ftmdamc1d;als_aud initial data
--------- __________________;2cc,6=3
Cantilevers l\,latmial : aluminium / steel Design in S(\Ctions accessible f01 public cotn)sponding to : Ebs / other Connection to pole: movable / fixed
Poles Standard spacing TP from front face of pole to track centre in m Minimum distance track side of pole to track centre TP 111 ; 11 in m l'viaterial : steel / concrete / wood l\founted or inserted steel pole Standard for steel pole Single poles, head-span structures or portals Termination poles : with / without pole anchor (guy) Standard for c011crete poles / steel poles
aluminium Ebs fixed / fixed 3,70 2,55 steel/ concrete mounted Ebs single poles with pole anchor (guy) DIN 4228/ EN 50 341-3-4
Foundations Standard spacing track side of foundaticm to track centre in m Type of standard foundation Type of foundations for difficult soil conditions Reinforcement : yes / no / if necessary Anchor bolt material Rating of pile foundations / concrete foundations in accordance with Earthquake risk Subsoil report available
3,70 (concrete pole) piling special foundation if necessary steel EN 50341-3-4 no yes
Railway earthing measures Earth conductor : yes / no Connection of pole directly to rail : yes / no Type of connection
yes flexible conductor
110
Safety clearances For short duration distance of energised parts to railway earthed parts in accorclauce with EN 50119 in nun For long dmation distance of energised parts to railway earthed parts in accordance with EN 50 119 in mm Minimum height of contact wire at railway crossings in rn
150 5,50
Electrical disconnect.or remote control Cable type Location of control unit, Use of trough d1a1mels · yes / no
NYY-J signal box Lh yes, where possible
Headroon1 Overhead contact line systeltl lluder structures in m Overlapping sectious uuder st 111ctmcs in m
5,90 6,20
6.2.3.2
100
New lines
Aft('r <·ompilaLion of tl1<) t<'dl!lical r<'.quirc111ents, fmther planning for a new hne requires info, 111atiou on the /nu:k layout, topo1rmphy, system, con,,sf'ro:ints and sozl conditwns. Detailed docm11entat ion oft !tis ittformatiou would be provided in the following format:
The surucyo·r's l(l,yo11I JJlo11. wlticlt shows Uw track la_vrn1t to a sndc of 1:1000 or I SOO, S<'pilt,ll,t'I\ for ()j)<'ll t til<"k and sli1lio11s. Tltis d1awiug is prm·idcd either in i\ll,dog111· [,11r11 ilS i\ p,,p<'I d!i\\\'ill,l!, ()!' i11 digit,;tl rorn1;1t. \\ !t('I(' ( II<' lilt tn is to hr
264
6 Planning_ of overhead contact line systems
preferred. A list of co-ordinates for track layout and gradient over the route. The permanent way transverse pro.file, as designed, for each pole location. Signal position layouts. The signal designs to be used follow from the technical specification of the signalling system. The dimensions of the signal, of the tread of steps and access ladders form the basis for verification of safety clearances between signals and energised parts of the overhead contact line system. The track insulation layouts, which provide a basis for the specification of the railway earthing. Cable layout plans and information related to underground services, v\'hich may impinge on pole foundation positions. A list of railway crossings to permit a check of the necessary thoroughfare clearance based on the kilometre distances and crossing angle. Bridge drawings showing mileage, headroom, bridging width and crossing angle. The pole locations, the contact wire and system heights under the structure and any necessary alterations to the structure can be obtained from this. Subsoil condition information, which forms the basis for foundation type selection and foundation dimensions. The soil conditions also give an approximation of the earthing resistance. If no soil documentation is available, then probing or other site investigations must be carried at selected locations during the project implementation planning phase. All parties involved in future planning, e.g. for the erection of buildings after the electrification, conversion of tracks and the extension of station platforms, are to be consulted during the design of the overhead contact line system. This reduces subsequent alterations and thus planning and construction costs. Information regarding tracks to be wired together with loading gauge details and details of specific routes allowing out of gauge loads. Electrical sectioning plan, showing the arrangement of electrical switches, insulated sub-sections and sub-section insulators. Information related to traction power supply lines; -such as bypass lines. parallel feeders, feeder lines and return conductor cables, which are shown on the overhead system layout and longitudinal plan. The planning of the overhead contact line system disconnectors for local or remote control, which requires information on the control location, the route and the cable type. Endeavours should be made to achieve co-orclina.tecl cable laying, An agreement between the customer and the contractor on the scope of the pro]ect to avoid duplication of work and misunderstandings. A project schedule to control the project engineering and aide achievement of the construction start elate. A joint review of the documentation is carri(xl out by planning engineers from both the customer a.nd the contractor. Agreement is reached 011 the necessary provision of missing documents and the\ rc\sulting effocts this drlay will hav<' on the planning process and the co11strnctio11 start date.
6.2 Fundame11tals a1_1~l i11itial d,ita
6.2.3.3
265
Existing lines
The dectrificatiou of e:r:isting lines is often accompanic\d by some track layout corrections. Tltc overhead contact line syst<)rn planning for such sections is carried out based on Uw documentation listed in sub-section G.2.3.2. Scaled layout drawings are required for line section without track layout changes. These drawings need to show signal locations, cable positions, supply and drainage piping, railway crossings, bridge on·rpasses and underpasses and information related to tracks to be equipped ·with OYerlwad contact line systems.
6.2.3.4
Alterations
Conversions to overhead contact line system8 are often preceded by track alterations similar to section 6.2.3.3. This work usually needs to be carried out in a number of stages. Staged construction conditions require additional information: Track layout is designed for each conversion stage. Station alterations often require several intermediate track 8tage8. Each of these requires track layouts and information related to the construction programme. An inventory or revised plan for the existing overhead contact line 8ystem. Invalid and outdated drawings may require that the overhead contact line system be resurveyed. J\Ieetings between parties involved in the project before and during planning assists co-ordination with other affected projects.
6.2.3.5
Tracks and topography
Track layout and topography are important bases for overhead contact line system planning. Track layout is shown in the layout plan. If an up-to-date layout drawing is not available, then the track layout and terrain profile must be surveyed prior to commenC(\!IlC:mt of planning. The most common form of track and terrain surveying is the terrestrial survey, during which the track layout and the track profile are recorded ,,, it h the aid of theocloli tes. Track layout drawings and transverse profile drawings at the pole locations are then created. PhotogrammetTic r-ecording8 [6.1] can survey tracks and railway profiles more rapidly. Stereo-infrared cameras record the line from a moving railway V<'hicle. Digitalisation of the spatial recordings is performed with the aid of a projector. An accuracy of 10 mm can be achievecL Aerial photos are suitable for the simultaueous n•cording of track layout and trans,erse profile. The flight [6.2] with a stereo camera. and tlw subsequent digitalisation, prm ides t.l1rec-dimensional dra·wings from which lungitudinal and transverse profiles can lw produced. Tlw accuracy is dependent upon t lie experience of the analyser and \"C').>,<'L;-lt.irn1 on Llw gro1md. i-\n accuracy of ±GO 111111 ca11 lie achieved. 'Ten ain smveving with the aid of ,1 c;to/)(l,l Poszt10111·ru; Sys/cw. ( GP8) is already an c•st;ililisll<'d rnet.l1od for ov<~rlread t.rn.ns111ission line planning . 1t is ('ltlployed on new mil\\;)\' li11<'S frn s111v<\Ying the trnC'k layol!I. and till' pole loc,it.ions prior Lo track const 1 ti< I iun I'll(' fit st. r<'ndiug ohs<'IV(~s a k11ow11 p()i11t \\'ltil<' t.11<' sN·o11d n~,iding recei-vC'S
266 Substation
cii
cii
D
D
Q)
Q)
.l!!
cii
.c
D
.c
C
JI!
C
0
Q)
(\J
Switched sub-section open line I
---
l:H -I-II 1:HI II
I I
I I
.0
.c
C
.Q
u25
I I
~
0
0
(\J
0
.0
C
C
['?
.Q
c .Q
'?
.0
•
----~--------
.£!
um
0----~~-------
i ___
:I- st . -1:
ii-
ation
I I
-Ii
11 II
-------- ------
--~---L -----------
L _________ -------------------- ---~- --open line feec1er section Station feeder section
I
-----1
Ii--1-----ii i-----1---111 -1:1 II II II -1~
open line feeder section
- -----~
Figure 6.3: Feeders and switched sub-sections at DB.
the co-ordinates of the relevant location from several satellites. More than 24 such satellites are currently in orbit around the earth, of which only several are available at any one time for a particular recording position. Correction programs [6.3] calculate the co-ordinates for the track layout and interesting terrain points based on the world co-ordinate system WGS 84 using the recorded data. By conversion, co-ordinates based on the Gauss-Kruger co-ordinate system with an accuracy better than ±10 mm can be obtained. The topography together with track, structures and crossings are also shown in the planning documents, as these features influence the type and dimensions of the supporting equipment, poles and foundations.
6.2.3.6
Circuit diagram
The planning work also includes the production of the overhead circuit diagram, which is designed to suit the requirements of network and railway operations as well as protection and overhead contact line design. A schematic track layout plan with signals, point connect.ions and important structures forms the basis for this planning. The substation supplies branch feeders with traction power by means of circuit breakers. On double track sections, often only three feeder branches are provided by DR (see Figure 6.3). These feeders are provided to the station where the substation is located and the adjacent track sections. \Vhere a single-track line runs parallel to a double track line, all overhead contact lill(\S aw fed from a single branch feeder; where two double track lines run in paralld, each line is fod from a separate hnu1ch feeder. The feeder branches are each snbdivid<~d longitudinally into s,vitdwd sub-sections. Overhead lines in stations and 011 the 01w11 track are fod b,· separat<'ly switched subsections. The electrical bouudari<'S hctmien Llie switd1<\d sub-sections <·oiucid<\ with the operational boundaries h<)tw<~<'11 t IH· op('ll trn('k i111d st;1tio11s (s<'(' ( li1us<' IO}i ). Switclt<'d suh-s<'ctio!ls ill sl;1tio!ls ill<' s1il>di\id<'d into <'ll'ctti(·,ilh S(!parnhl<' swifchzng
6.3 Contact, wire sta.g,g<)t ancl hori;r,c)ntal forces
137,8
137,9
I
I
?;
I
~ electric
PH RC
~
= point heating = return conductor line
station boundary
;;g/; l,m 137,820
Figure 6.4: Extract from a line diagram with switching instructions for a typical statiou.
groups. Ma.in lines for passenger and freight traffic and secondary tracks each form separate switching groups. Sub-sectioning of switching groups on main tracks provides benefits for maintenance and repairs in long stations. The design of electrical sectioning of the overhead system should always be carried out in consultation with the relevant train operations department. Figure 6.4 shows an extract from a single-line diagram with switching instructions for a typical station. The normal disconnector position is to be defined in the overhead line switching diagram. Switch1;ng sectfon boundaries are designed as insulating overlaps in through tracks and arranged such that no traction vehicles can stop with raised pantograph within the insulating overlap when the signal is in the stop position. Electrical disconnectors can connect the overhead lines at the overlaps. Switching sections and switching groups ca,n be interconnected with electrical switches. Auxiliary loads are feel frorn the overhead line via disconnectors. Overhead line switching and disconnector id
6. 3
Contact wire stagger and horizontal forces
The c011t;--1c-t wire Yi<~W<~d iu t.h<' contact plmtt' is not strung paralld to th<' Lrnck n~utn' line. This is to avoid 111wv< 1t W<'at of th<' carbon rnlleclor strips 011 th<~ pa11tographs and t.o g1i;t1antce c-onti1111011s <·outad, iu curves and under \\·iud action. Inst.cad, it is st rnng with au 11,l/,1'TnuJ,in1J lall'ral 1hs1,la1:c'f!l,en/, along th< trnck, also k11ow11 as a zuvag or slu,_rJ_tJ0 and ;~;H). s<'<' Figur<· G.G, for tit<· rnn·<' sit11,ttion see \·'i_~lil<'S (j <'-\ ,\ltd (j () 1
1
1
, 268
/il
Switching post D-town South
•··············· ••••;•,!
SS G-town
substation (SS or SP) railway station line branching
Figure 6.5: Extract from a line feeder diagram.
-
---- -
- -
-----
..._
-
--
Figure 6.6: Contact wire stagger
011
straight trade
Q:! Contf~ct wire stagger and horizontal force:=; .c 0)
Catenary wire _ stagger
C Q)
-
+
-1
1=
Ol
iii .c C 0
:ffi ai U) C
.c 0) C
Pole inclination
_J ___,, _ _ _ _ _ __
~ Q)
0
0..
Plane of top of rails
0
Measuring bolt
D Ol
C
§ (f) cu Q) E
__L,, 1
,.,,,,,,.,,
Distance TP track centre pole front surface
:::J (f)
:£.
u
cu i=
Figure 6. 7: Designation of dimensions at overhead contact line supports.
-:: ieperrnl
--- ----== C .:::-.,,.:::_
e:errn\ - -
--_:J -
_::. -=-~-
---=-
~-------_-.-.....-...:
Figure 6.8: Contact wire stagger in curves with large radii.
At DB, with overhead contact line system types Re 100 to He 200, the catenary ,vires on straight track are located at the supports vertically abme the cen'.,re line of the track and in curves, vertically above the contact wire. Hm,c'v<:r, the catenary wires 011 overhead contact line systern typc!s He 250 and He 330 are r\tTc\llgcd vertically above the contact wire both on straight track and in curves. \ Vli<'ll specifying contact WU'e sta_r;ger in curves, the wind displacement of the contact wir<' is taken into account for both tlw inside and 011tside of the curve,, The ruaxinrnrn co11t i\('(, wire position displaccntellt within a span s!tot1ld lie less titan or equal to frnax (S('(' Figllr
270
__________________ G_Planning ofo,erlwad contact line systems
Table 6.2: Span lengths, contact wire staggers at midspan (dirncnsion "c") and at support (dimension "b") for DB overhead contact line system type Re 200 relative to track radius, for wind speed of 26 m/s in accordance with DB Ebs 02.05.06.
Radius fl
Span-
DillH)!lSiO!l
length
u{)''
{
bi
Ill
Ill
mm
00
80,0 80,0 80,0 80,0 80,0 80,0 80,0 80,0 80,0 80,0 80,0 79,8 77,5 76,2 74,7 73,2 71,6 69,7 67,7 65,1 62,5 59,8 56,1 52,4 47,9 42,5 38,6 33,4
--100 --100 --100 --100 --!00 --100 --!00 --!00 --100 --!00 --100 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00 --!00
20000 10000 7000 5000 4000 3500 3000 2700 2400 2000 1800 1600 1500 1400 1300 1200 llOO
1000 900 800 700 600 500 400 300 250 180
-JOO
--!00 --!00
Dimension "c"
b2 mm
IIllll
+400 +320 +240 +170 +so 0 -60 130 -190 -270 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400 -400
0 0 0 0 0 0 0 0 0 0 0 +40 +70 +80 +100 +120 +130 +150 +170 +190 +210 +230 +260 +290 +320 +350 +360 +370
In curves with smaller radii, the contact vvire is only staggered to the outer side of the cun-e. The varying contact wire stagger ou urban transportation S_\-stems should, far as possible, also achieve even wear of the contact strip. \Vinci displacement should also be taken into account, as on main lines. It is convenient to commence the configuration of the contact wire stagger in curves, since the lateral position is ddined by the track radii. In transitional curves, a. change
./ ·J
/. ·
Figure 6.9: Contact, wire stagger i 11 c\lrves with :-;mall radii.
6.3 Contact, wire -
0,90
m
-- -------------------
- - -271 -
- - - - - - - - - - - ----_-------------------------------- a) -<:_
-
8 pcrm _. ...._ ..-- _. __________ c 1 = 0 Wind displacement for v ;:::--26-07/s --------------:::: ------------____ _ --:.,;:.--c. ___________________ ------::::...---
0,60 0,50 0,40 - -
-----
0,30
0,20 ..-- _. Contact wire in still air 0,10 .,.0,00 - '--- Track centre line -0,10 -0,20 -...... ...... ~ eperm -0,30 ...... -0,40 -0,50 + - - - - - - - , - - - - - - - , - - - - - - - - , - - - - - - - , - - - . - - - - - - - , - - - - - - , - - - - 4,50 0,00 9,00 13,50 18,00 22,50 31,50 m 36,00 27,00
--- --
1,20
- - --
b)
-- -- -.r<::-::.-~----=-:_-::-_~ __
m 0,90 0,80
--
-
......
......
--....
.,.- <--e
'
g:;g __ / / / £;:-__~_9~r:!_l:-__-:::_::__-::-__ ---.. , '- , g:;g ,_______ / __.-::___ ---------------- ----w-----..r - -------------- ---------------/ ....
7
perm
0,50
0,20 0,10 0,00 -0, 10 -0,20 -0,30 -0,40 -0,50
C
~/
- - - - - ------;::-.,,..-
/
4.
-- /
/
~
/
-::::..-
--
-- --
-
-
-
-- -
___ -
' ......
......
.......
eperm
--
'
'
.......
/
' ' ' m
- 1 - - - - - - - - - - - - . - - - - - - . - - - - - , - - - - - - - - . - - - - - , -I - - - - - - - , - - - - - . - - - - - - - - - - - ,
0,00
5,99
'
11,98
'
17,96
'
23,95
29,94
'
35,93
'
41,91
47,90
Span length I -----------
Figure 6.10: Contact wire stagger in a span, (a) for c 1 = 0 mm with l = 36 m and (b) for c2 = 320 mm and l = 47,9 m for DB overhead contact line system type R.e200 with a wind speed of 26 m/s.
of the contact wire from the inner to the outer side of the curve can become necessary. The distance between the contact wire in still air and the centre perpendicular to the plane of the top of rails (canted track centre line) at the centre of the sp,rn, also known as dimension "c" (Figure 6.8), serves as a method of checking the contact wire position with side-wind. Table 6.2 shows the band c dimensions and the span lengths for overhead contact line system type Re 200 for a wind speed of 26 m/s. The calculation of w1.nd displa.cem,ent given in chapter G guarantees a correct contact wire position in the span for deviating dimensions. Table 6.2 contains the contact wirP stagg<~L at st1pports, for overhead line type He 20(L The determination of tlw spall length is based on static contact wir<' sfa111w1 plus wind dl
_ ______ 6 Planning of overhead contact line systems
272
I
.. --~--·-~-~·---
-"----·~---eporm
Figure 6.11: Contact wire stagger in overlaps_ Support C
Support A
Support B
Figure 6.12: Determination of distance k at support B
The distance between the contact wires in overlaps is fixed depending upon the type of overlapping section, i.e. air gap insulated or uninsulated tensioning overlaps, and the operating voltage. The span lengths and the contact wire stagger at the supports (Figure 6.11) are determined from consideration of maximum wind speed and the permissible lateral contact wire position emax· The distance between the contact wires at DB is 450 mm at insulated overlaps, and 200 mm at non-insulated overlaps. In 25 kV systems, SNCF employs a distance of 500 mm in insulated overlaps and 200 mm in non-insulated overlaps. Radial forces occur in contact and catenary wires because of the change of direction of the overhead line at supports. The radial force FI-I of the contact wire should remain within a specified range, e.g. at DB within the range 80 :\ < FH < 2500 N for a light-weight steady arm. A shortfall can occur as a result of an insufficient contact wire deviation at the support. This condition may be tested by using equation (6.1) and Figure 6.12 (see also chapter 5).
(6.1) with FI-I
Hew k l 1, l2 l~,
z;
contact wire radial force in N contact wire tensile force in N distance between the examined support and the line connecting its neighbouring supports in rn (Figure 6.12) span lengths in lll contac·t win~ length lwtween the supports in m
Sufficient acc11nic_,- may lw ad1ievwl by letting l' I . Th<' dist ,rnce /;; can either be calculated or deri,<~d fron1 a, distorted scale overhead li1w la:,011 t 01 a CAD layout plan. For span lengths / 1 = I 2 = GS m and a contact win~ stagge: on straight tracks of b = 0,30 rn, with a rnntact wir<' teusil<~ force Hc1vv - lS k\T. a crn1ia.ct wire rndial force F11 = 27(U) :\ r<'sults. Tl1is is gn•,1ter tlrnn the mini1111m1 t,1di,d f<>rce F 11min = 80 N.
6.4 Detenni11aLiou of spm~_l~)l1);,ths
273
90 m
80 -
····-
·------ 1 - - - - ·
.
---
----.-- ---- -~--------- - - ~
170
-
-~
_,,,-/' '!"'.,...,.. ;:_,:,._.,,.-,.,..
:-;~ -·~
-
/
40 -
V
l.----
/
/4
V
-
-
-
.,..,:-1/
.,:;-
30 0 0
0 0
C\J
C')
0 0 lD
0 0
(0
---- ------· ,-
---
~
/ .,L_
v?
i---
0 0
I'-
0 0
CX)
g 0)
0 0 0
0 0
0 0
~
C\J
Track radius
0 0
C')
0 0
sj'
0 0 lD
- - -
-- -
Span length for Span length tor Span length for
0 0
(0
0 0
I'-
·-·--
0 0
CX)
- - - -
-
26 m/s
V
v = 29,8 m/s v = 32,1 m/s
0 0
0)
0 0 0
C\J
0
0
~
C\J C\J
om o C\J
R ------
Figure 6.13: Span length dependent upon track radius for overhead contact line system type Re 200.
The radial contact wire force can be increased by reducing the span length or increasing the conta.ct wire stagger at the support. It is possible to exceed the permissible value through excessive deviation of the overhead contact line system and a wind force acting in the same direction as the radial force. The radial force must therefore be checked in conjunction ,vit.h the wind load. The detennination of radial forces also forms the basis for examination of pole torsion in accordance with clause 7.5, which can arise when two cantilevers are installed on one pole.
6.4
Detern1ination of span lengths
\Vhen de.fining pole locations, for reasons of economy, one should exploit maximum permissible span lengths as far as possible. Pantograph width, track layout and prope1ties and wind speed determine the span lengthi:i (see clauses 4.1.4 and 5.5.2.4). Short useable pantograph contact strips, track curw\s and high wiucl speeds reduce span lengths, Figure -1.4 illustrates the relationship b'.'tweeu pantograph width at various railway companies and span length. Figm<\ G.13 shows the dependency between track radii aud span length using th<\ example of DD overhead cont.act line system type: Ifr 200 for wind speeds of 2G m/s, 29,8 m/s and 32,1 m/s, iu ac-rnrdaucc with Ebs. Span l('llgL!ts fm overlwad contact line system type Re' 100 are also shmvn i11 Figure 6.13. (h<~rlH'ad contact li11c! s_\·st<~ms Be 250 ctll(l [{e :BO are us<~d for high-speed lines with track rndii gre,1t.er than :3000 111. Tlwse sys(,c~111s C'mploy a 111axi111u1t1 span length of GG tn Lecat1s.:2.-1 descrilH~s the definition or Sj)i\11 l<'llg( Ii ill ddail.
__Q Pl_,1:1~~1i11g_9£()verhead c:ontact line systems
274
C:
f
14
I
13
I
0
I
8: 12
I
::J
..':: 11 0
I
~ 10
§ z
I I
9 8
0 0
0 0
0 0
0 0
0 0
C')"Sj"l.[)(Df'-
0
0
0
g g gC\I
0 OC\I~
0
~
C\I
0
gC\I
0
0
C\I
C\I
~
~
0
0
0
gC\I C\I 2 g C\I
m
0
g C')
Track radius R - - -
Figure 6.14: Dependence of the number of supports n per half tensioning section length upon radius R for overhead contact line system type H.e 200.
6.5
Tensioning section lengths
Tensioning section lengths are defined as the length of overhead contact line from tensioning device to the other. The overhead contact line system including steady arms and cantilevers moves in the direction of the tensioning device with increase in temperature. A component of the longitudinal contact wire force acts through the cantilever in the direction of the pole due to rotation of the cantilevers. This causes a difference in the tensile forces of neighbouring longitudinal spans. This force is also known as the restoring force. The tensile force differences in individual spans are added to each other in curves and lead to the greatest differences in the span at the midpoint anchor. To limit the tensile force differences near the midpoint anchor, DB reduces the tensioning section lengths on curved track. as the curve radii decreases. In total, a horizontal force reduction in each of the half tensioning section lengths of approximately 11 % is permitted in the catenary and contact wires, ·which distributes itself to 8 % on the overhead contact line system and 3 % on the tensioning device [6.4]. The maximum number of supports n is dependent upon the track radius Rand can be determined for a standard contact line system of type Re 200. with HcA = 10 kN and Hew - 10 kN, wind speed v = 26 m/s and a cantilever length of 3,5 min accordance with Figure 6.14. One determines the half tensioning section length in a curve by determining the span length as a function of the track radius and considering the wind speed. The half tensioning section length L is therefore dependent upon the achievable span length l as illustrated in Figure 6. E>. The foll0vving numerical value equation is valid for DB [G.5]
L
=
7·l
+ 190
L lt1
(6.2) Ill
Equation (G.2) is valid for on!the,.td co11tact !in<' svste111s with rated forces of 10 kN in tlw catenary wire c111d co11Lwt wirP, a wi11d sp<'<'d of 2G rn/s arn! ,1 lateral displacement of O,cl m. Thus, tl1<' nrnxi11111111 li,df tc•11sio11i11µ, sc-ct io11 l<'ngtl1 is 7GO n1. Using [G.G], an npti1nisc•d J(•];itio11sl1ip lH'im'('ll 1l1<' li,df te11sio11i11g sect.ion length and s11pport spacing is ,wl1i<'\<•d !(11 ;i 11,wk to p\' t;iking ,-tch,rntage
275
900 m
800
i'1
,.
,. ,.
,.
,. ,. ,.
,. ,.
,.
;
700
E -.J
.c
Ol C
600
..Q? C
0
t5 500 Q)
(I)
Ol
sC
0
iii
400 L = 7-1 + 190 [6.5] 2 L = 11,8 I - 55 [6 6]
C
.2:!
m 300 I 200 40
30
60
50
70
m
80
Span length
Figure 6.15: Relationship between the longest permissible tensioning section length and the span length.
1000 . , - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - , - - - - - - - , - - - - - - - ,
m 900
Number of spans for condition 1 and 2
9
10
11
- t - - - - - - - + - - - - , f - - - - - - - - - + - - - - - - + - - L ~ . , . _ ' _ , _ _ - - + - - - - - - J . . - - - - ---!---
_,.,
___
i'1 E 800
/ 2 -l------1-~<---
------------
.,,.,."
,.,.' ---~---+--------+-------+-------,-----~·~--- -
-.J
DB
NCF
1 Distance track centre line/tmci< side of mast 2 0 m
m I
400
2 Distance track centre line/lraci< side of mast 3 0 n 1
300 - f - - - - - - - - - , - - - - - - - - + - - - - - - + - - - - - - - + - - - - - - + - - - - - - f - - - - - - - - - , 600 1400 ill 3000 200 1000 2200 2600 1800 frack raclius R
Figure 6.16: 'lbtsio11i11g s<~dio11 kt1gtli as a fnuct.iou of radius.
6 Planning of overhead contact line systems
276
Switching section boumjary
F=u
t~-J/
IOI ~l[L,
PS Station
Overlap
Open track
o-1 BS
Figure 6.17: Arrangement of insulated overlapping sections relative to signal locations and points. BS = blade start of point
of the permissible restoring force for the same overhead contact line systems. The numerical value equation applies
L
=
11,8 · l - 55
(6.3)
It follows from this that permissible half tensioning section lengths of 750 m are also achievable with span lengths of 68,6 m and a greater number of spans. The largest achievable half tensioning section length is of significance for planning of overhead contact lines. Based on equation (6.2), whose validity is also assumed for SNCF, half tensioning section lengths are calculated and shown in Figure 6.16 relative to the radius of the track for DB and SNCF. The span lengths were determined for DB in accordance with (5.63) and Figure 5.11. They apply for the standard overhead contact line systems for speeds up to 200 km/h. The values in Table 5.9 are valid for SNCF. According to [6.6], the achievable half tensioning section lengths, which result when the permissible tensile force losses of 8% were found for different cantilever lengths lA, are fully utilised. These results are also illustrated with the necessary number of spans in Figure 6.16. Half tensioning sect.ion lengths larger than 900 m are not achievable. The tensioning section length is also dependent upon the working range of the tensioning device and the temperature range of the overhead line. See chapter 5 for more details.
6.6
Overlapping Sections
The subdivision of the overhead line into switching sections as described in section 10.-5 requires switch:iny sectwn boundaries between stations and open track The insulated overlapping sectwns planned there must be protected by signals. L e. a traction vehicle stopping at a. stop signal with its pantograph raised max nut be located within the insulated overlap spans betwc~en the entry signal and the entn point. The distance a shown in Figure~ G l, defines the positioning of the overluppwq span relative to the signal and reprcs<'nts the distance lwtween the signal and t]l(' first pole of the spans with two cantil<\v<~rs. Distance a applies as follows for: Standard lines ,vith 1· 11 1x < 2:30 km/It Sul>urhan rapid trnnsit sysl.<'tlls i;
1()() Ill 2()() l ll
6.7 Contact_liuc,tl>O_v<\ I><>ints _
Lines equipped with CIR-Elke (CIIl-Elk<~ stands for: Computer Int,cgral,<~d Railroading to increase the performance of heavy-duty network ) High-speed lines with '/J 111 ax > 230 km/h
277
410 m 500 m
For standard lines operated at speeds up to v 200 km/h, the distance ltotal between the signal and start of the first point of the station is dd.ennincd as shown in Figure 6.17. The distance l1.otal between the signal and point start rnust therefore be at least 205 rn for contact line type Re 200 with l - l 1 - 65 m for a threc-spall overlap. This ensures that an approaching traction vehicle with raised pantograph has already reached an adequate speed when it passes the overlapping contact wires, guaranteeing that spot heating of the contact wire caused by current flowing between the switching sections via the pantograph does not lead to a contact wire burnout. Overlaps on double-track lines are arranged in parallel to each other. Owrl1c!ad line poles are to be positioned at least 10 m from signals. Various types of on'rlaps arc described in clause 4 .1.11.
6. 7 6. 7.1
Contact line above points Introduction
Pole locations and contact win~ stagger at track points or turnouts can be configured only within tight limits. The wiring of points requires special care, since large contact forces between the contact wire and the pantograph can occur there. Wiring is aimed at optimum pantograph passage on the through-track and safe passage for all other directions. Examination of an individual track point can serve as the basis for the wiring. Hmvevcr, only consideration of the track point as part of a crossover, a station yard la~·out and the loca,l conditions, such as track spacing and the posit.ion of points to each other, results in satisfactory vviring.
6. 7. 2
Designation and drawing of track points
The term track point is used here as a general term for 110'1,nts. rlou/Jlc-slip c,ossovr:rs and shp sw'itches. Oiffen)ntiation is also made between through-tracks and lna11d1ing tracks as in [G.7]. A through-trad,; is the designation allocated to the straight track at single points. At curve points, it, is the straight track iu t lie associated basic form, or the track with the higlwr operational prioritv or heaviest, lrntd. l11 Figtm'. G.18, the abbreviations have th(' ttt<'clllings PS 11oint. sto:rt. PC point r:r:.ntrc and PE pmnf end. If a circle is dra\\'ll from the start oft he point wit.Ii the radius of Lil<' hra.rwhing track, then th<' end of tlw point in the hrnn< h track is located where the L111g<'.11L of the circle rcadH'.s I : n and tlic point <"<'nit
G Plannjr1~o_f__()~~lwad contact line systems
278
----------~--
--
p
Blade
a
'-~ "& Check rail
Branching track PE"
~
'
~~
Figure 6.18: Layout of a point.
a)
~ Q)
PE
~ :5
PE
gi E
(/)
PS PC n Units of measurement
b)
PC n Units of measurement
Figure 6.19: Illustration of simple points with point diamond apex in track layout plans.
of the point PS does not correspond to the start of the switchblade BS for geometric reasons. The tangent representation as shown on Figure 6.19 a is used to illustrate poinr.s in layout diagrams in simplified form, which cannot however be used for point wiring. The wiring is made possible only after entering the radius into the track point drawing in analogue and digital diagrams (see Figure 6.19 b). The parameters branching track radms R and point branching angle 1 : n determine the type of point and point pa.ssage speed for t lw branching track. Simple points can he passed as follows: Branching track radius R = 190 ll l lip to speed V= 40 km/h, ;100 l tl 11[> to speed '/) Branching track radius R = 50 km/h, 0 ()() '/) Branching track radills R l ll llp to s1wecl 60 km/h, Branching trac·k radius R ·7GO ll I 11 j) lo speed '/!= 80 km/h, Branching tra.ck radius R= 1200 Ill ttp Lo speC'd '/!= 100 km/h, Branching track radius R 2:i00 111 ttp 10 sp<\ed v = 130 km/h Considerablv high<:r spe.c~ds ,m~ possi h!(' ()11 t 11(' 1.11 rough-track. Clothmdal poinf.c; as wdl permit higll(~r sp('
6. 7 Contact liun above points
279
't:.
i
E 0 0 0 0 ~
II
er:
E 0 0 0
\\
set II 0::
Figure 6.20: Cmvaturc at a clothoidal point.
PS
Knowledge of the track point, de.':iigr1,ahon and then track point type identifier arc essenUal prerequisites for wiring of points in practice. The track layout diagram contains only the standardised point desi_qnation. The conventions at DB arc
60 - 2500 - 1 : 26,5 fb
l l
l
Supplementary designation: Point diamond movable,
Angle of the tangent 1 : n with 1 : 26,5, Radius of branching track 2500 m, Rail type UIC GO. The branching track has a constant curvature with the aforementioned point form. In addition, clothoidal points ·with variable radii on the branching track arc used on high-speed tracks. Track changeover speeds up to 200 km/h can be achieved in this manner. A typical clothoidal point designation would be
GO - 10000/4000/oo -1 : 39,1131
l l
l
Angle 1 : 39,1131 Radii R 10000 / 4000 / oo m Rail type UIC GO.
Figure 6.20 illustrates the cmvature of the annotated clothoulo,l pm:nJ,. The followings speeds are possible on the branching track of dothoidal points for track c0111t< ctions UIC-60-3000/1500/oo - 1:20 fh Hp to speed v = 100 km/h, UIC-G0-4800/2450/oo - l:"G,5 f!J up to speed v = 130 km/Ii, UIC-G0-10000/4000/oo 1::3:J,5 fb Hp to speed v lGO krn/li ;-wd UIC-GO-lG000/6100/ oo - 141,5 fl; Hp to sp<)ecl ·n = 200 km/it 1
011:1·ued 7;oi11L-; provicl<' track cl1c1ttg<~m'er operations in curves. They ar<' forn!<)d lJ\ turning th<' point triangle arol!nd Lit<' point e<)lltre point. by the angle n \\'ltil<' rdaining the t;-wgcnt [<111gth / and LIL<~ poinl ;-utglc nw as shown in Figiue G.2L ff Lit<' rnn<' <"<'ntrns of the thrnllgh and !Jrn.ndting lnwks with radii R 1 aud H1 , u•sp<'cl,i\r'h-. lie 011 opposing sides of Llw point. ;-1ft,<'r p<·rforn1ing the rot.at.ion, then one• n-fns Io 111<' point as n umfn1:ry fki:un· IUJ"'ll(/'11,f ns sl1om1 i11 Figtm~ G.2 l li. Tli<' c11n<' c<'lll tcis uf si111iL1r flexllr(' poitt!S [i<' Oil (Ii<' S,1111(' side• of I II(' S\\itclt (Figlll<' (j '21 c)
GP!a1tuiug~ol_gy~rhead contact line systems
280
PE PE b) :~
---===~R~ad~·1~us~R~~~~~~~ Radius R 2 ,
I I I I I I I
c)
I I I
',---===::::=====--~:=:;::::--~------Figure 6.21: Design of a contrary flexure turnout (b) and a similar flexure turnout (c) from a simple point (a).
PE
Table 6.3: Heights of rail types. Rail shape
S -!l
S 45
S 49
S 50
S 54
S 64
UC 60
R 65
Rail height H in mm
138
142
149
152
154
172
172
180
If the point data are not known, they can be determined from the track layout in the following manner. The objective is to find the PS, ,Yhich serves as the fixed point for the wiring of the point and the longitudinal placing of the poles. The measurement of the rail section height provides the rail type as shmvn in Table 6.3. The camber process in accordance with equation (6.4) and Figure 6 22 assists the determination of the branching track radius R.
R = l§/(8 · hr) The start of the point can he localised on site with the rail type, the branching track radius and the dista.nce a between the point blade and the start of the point as shown
Figure 6.22: Dei.(~rmina.ti()t1 oft lw branching track rndi1rn 11sin~ th<· c;unhP1 fir witl1 1lt<• length of the • I
d1()nL
6.7 Contact li1w above poin~s
281
Table 6.4: Distance a bet.ween start of the point; PS and the start of the switchblade. Switch
EW EW EW EW EW EW EW EW EW EW EW
60 60 60 60 60 60 60 60 60 60 60
Lyp<'
for rail shape UIC 60
300 - 1 : 9 300 - 1 : 14 500 - I : 12 500 - 1 : 14 760 - 1 : 14 760 1 : 15 1200 1 : 18,5 2500 - 1 : 26,5 4800 / 2450 - 1 : 24,257 - 6000 / 3700 - 1 : 32,5 - 7000 / 6000 - 1 : 42 -
Distance a PS BS in mm 805 805 805 805 805 805 805 2005 2402 3102 4723
in Table 6.4. A check of the point position and longitudinal placing of the poles into the station or out onto the open line is performed after determining the start of the entry or exit point and making a mark on the rail web with the marking PS.
6.7.3
Principles of overhead contact line wiring at track points
Intersecting and tangential overhead contact line system wiring is possible for the overhead wiring of points, dependent upon the type of point and the pantograph width. The negotiable contact wires cross the point when 1.nter·secting point wiring is provided. The contact wires are fixed vertically to each other at the contact wire crossing by means of a crossing bar. The contact wire that is not being negotiated is also lifted by the crossing bar and crnssover dropper, so that locally fixed positions are created for the pantograph switchover from one contact wire to the next. Tangenbal sw'l.tch wiring locates the contact lines in parallel to each other, in the sa.me manner as in overlaps. The contact lines do not intersect in the negotiable section of the parallel contact wires. Tangential switch wiring can be realised only when the points are slender and the pantograph vvidth permits the paralleling of the contact wires.
6.7.4
Fitting-free area
The pantograph is in contact with both contact wires iu the area of the point for a short period. The contact wire of either the brallc-hing track or that of th<) through track nrns up the side of the pantograph. A risk of rnllisiou between the crnttact strip aud any obliquely i11stalled fittings is present due to the dvnamic uplift. E:x:amiuations [6.8] hav<' localis<'d this r<'asou as a sou1-c-P of faults and lun<' !(,ad to th<' declaration of a ./itl1:1u1-fn:!'. area. The fit.tiug-fr<'<' an~a is fonnc)d llltd<'r consideratiou of tlw dynamic uplift of the pautogrn.pli and t.h<' latc)rnl mm<~m<·rit. or t It(• \<:hie-I<',<'. g. at DB vvith a width of J;-J() rttllt as sliowll i11 Figmc G.2T.
G Pla1111ing of overhead contact line systems
282
Filling-free area for contact wire run-up and run-off
Centre perpendicular to lop of rails (canted centreline)
Pan-head profile displaced vertically and horizontally 450
Q_
CWH ist ::i Lateral displacement I of the ,~ontact wire at the support 400 I 400
0
(0 (')
-,-
Collector strip width 1030
___________________,
,___
600
600
I 250 75 75 250 Pan-head operating range 1450 ----------·~·1--------------l---'------"'.---"'------------""'\,-<-l---Emergency range
Total width of I pan-head 1950
Emergency range
I 1_ _ _ _ _ _ _ _ _ _ _ 10_5_0_ _ _ _ _ _ _
_1._________ 10_5_0_ _ _ _ _ _ _ _,
All dimensions in mm CWHexist: existing contact wire height Uplift in accordance with EN 50 119
Figure 6.23: The fitting-free area at DB. a)
correct
b)
---
still permissible
--~? I
c)
incorrect
©
\
Approaching contact wire on branching track 0 Through track contact wire - Centre perpendicular to top of rails @
Figure 6.24: Approach conditions for contact wires of contact lines above switches.
The fitting-free area to the left and right of the track centre line, measured from the centre perpendicular from top of rails is to be kept dear of feeder fittings, contact wire fittings, stitch wire fittings and insulators, taking into account deflections caused b_v wind, wedge-type dead-end fittings and butt connections or contact wire splices. Railway companies in Svvitzerla.nd, Norway and Russia also define a fittzng-free area.
6.7.5
..
Arraugement of intersecting contact line wiring at points
To achieve a satisfactm_\· quali!.v or 1wrforn1,111<-<' of the ovr\rheMl wiring above a track poi11t, the followi11g rnl<'s appl\·
6. 7 Contact'. li_1w above points
(1) Contact wire toud1,ing is to be anticipated at a certain distance between contact wires. At DB the distance amounts t.o 1,05 rn lwtw<\Cll the centre line of the negotiated track and tlw approaching contact wir<'. corresponding to the width of the pantograph. From this point onwards, both contact wires - those of the through track and the branching track - must be located between the two track centre lines. The leading contact wire prepares for the contact wire mu-up by means of an inclination of tlw pan-head, as shown in Figure G.24 a. The zero position of a contact wir-e is permissible; i.e. the contact wire is located at the centre perpendicular to the plane of top of the rails (Figure G.24 b). If the leading contact wire were to be located in the opposite half of the contact strip to the approaching contact wire (Figure G.24 c), then a risky contact wire approa.ch would occur, which is known as a pantograph trap. This could lea.cl to an overhead contact line failure. (2) Only one contact wire should be negotiated at supports. to avoid hard spots. (3) For branching track contact wires uplifted by up to 150 mm at support I (Figure 6.27), the bend angle of the uplifted negotiated contact wire at the common support may not be more than 5° on through tracks and 15° on branching tracks. Larger bend angles can be permitted for branching track contact wires that are uplifted at the suppmt by more than 150 mm. They are considered non-negotiable. ( 4) The contact wire crossing is to be arranged as far as possible from the supports. The branching track contact wire can then be raised at the support to a height where the pantograph cannot reach as a result of the d;vuamic uplift on the through track. (5) The distance between the contact wire crossing and the centre perpendicular from the plane of top of rails on the through track should be smaller than the distance between the contact wire crossing and the centre perpendicular front the plane of top of rails on the branching track. (G) The span length between the point supports I and II is to be selected so that the contact wire positions in the through and branching tracks rernairt within the permitted limits under wind conditions. (7) The _fi,ttfr1,g-free area ensures a safe transition bet,Yeen the contact lines and 11111st be obeyed. (8) Irrespective of other criteria such as ,vine! displacement and the restriction of span lengths, the pole spacing should not exceed Go m. These criteria shall ahvays lw olis<'n<~d at speeds abo,·e lGO km/h. A rn1t1prnllliS<' is possible for requirements ('.2), (:3) attd (4) at lower speeds. Th<' crit<'ria ll<'<'d l)(' observed only if the point geometry p<'rlllits: this can heco111e impossible at radii of l :200 tu and less with contact win\ t<)ttsil<' fon-es greater than 10 k:\. Th<' use of points wi!l1 radii gn~ater than 1200 m tlwrdon' lwrnlll<'S It<'C<\ssary for high-speed litt('S
·-· -~_Pl,uming of overheacl contact line systems
284
Figure 6.25: Markings in distorted track layout diagram of the points.
--ll-+--1--
CWH
'57
Centre perpendicular Centre perpendicular of the through track of the branching track
6. 7.6
Figure 6.26: Profile clearance between supports II and the pantograph (see Figure 6.27).
Definition of supports for crossing contact wires at track points
The definition of the contact wire layout and the supports can be performed either locally on the track or in a layout diagram. The distances to the fitting-free area and to the profile clearance of the supports when traffic is present on the neighbouring track are measured locally. A magnification of the track layout laterally to the centre line, e.g. with a ratio of 1 : 10, is very helpful when wiring of the overhead contact line at a point is performed in a drawing or, when using a CAD program, on the screen. The verification of the contact wire qeornetry undr.r wind conditions, while observing the fitting-free area, can also be performed safely using a cha.gram. The fitting-free area should be identified in the magnified track layout diagram as shown in Figure 6. 2:J. The locations of th() profile dimension Br, the start of the overlapping section Br·. the c011L1ct wire crossing B 1 and the position of the support I B 1 should also be 111arked TlHi profile dimension BF guarantees a collision-free passage of the pantograph at support II as shown in Fignre G.2G and is 1,22 rn at DB It results from the sum of th(• hori1/otttal movement of th(' pantograph AF and half of the pan-head working rang<' S/2 Tl1c posit.ion \\·her<) tli<~ spn!ad is equal to BF is to he marked in the poi11t la,o:1t di,,g1;11n
G.7
Contact li1w above P?lr1ts
28-5 Support II
Support I
I
PE
I I PS
Througl1 track contact wire
/
/
Granching track contact wire
Figure 6.27: Preferred position of contact wire crossing at switches.
It results front the sum of the horizontal movement of the pantograph 6F' and half of the pan-head working range S/2. The position where the spn\ad is equal to BF is to be marked in the point layo'/1,t diagram. The overlapping section begins when the distance between the centre lines of the through track and the branching track is equal to the fitting-free area plus 600 mm. At DB, Bu = 1,05 m as shown in Figures 6.23 and 6.25. An overlap of the contact wire is to be expected from this track centre line spread in the direction of the start of the point. Both contact wires are to be routed from the start of the overlapping section to the contact wire crossing position BI< so that they are located between the track centre lines, including wind conditions. The contact wire of a track can lie on the centre perpendicular from the plane of top of rails during ,vind conditions (Figure 6. 24 b). The contact wire crossing is conveniently positioned when the track centre line spread Br< is as shown in Figure 6.27: (6.5) For this, bI
1
1
286
----~ G Planning of overhead contact line systems
Support I
x
1- - -..
Range for support II on branching track
Fi~:~:l "°' ~
I
I
-1mM~mn~mm1!Mlfl.MmflH/W11tttttf1I1Il1111l111JJW111JJli!l.1Jj.WJd:±tt1f111lLJ1llllllj~~w~ 1
-------=::
'PS
I
0,55
Figure 6.28: Routing of the contact wires above points. Support I
Preferred position of contact wire crossing
Support II
X
PS
Figure 6.29: Position of contact wire crossing.
accordance with the rules described in section 5.3. Values lsKs and lsKz are not equal since the different contact lines are not equal. The profile clearance Bp for pantograph passage on the through track relative to support II on the branching track and Yice versa (Figure 6.29) is also decisive for the values lsKs and lsKZ· At support II, it is beneficial to place the thro'Ugh track contact wire near the track centre line, to ensure that the contact wire is positioned in the overlap area is between the track centre lines. The possible range for support II on the branching track is determined by a parallel to the centre line of the through track at a distance equal to the profile dimension Bp, by the permitted lateral position bz of the contact wire at support II of the branching track, by the distance lsKz, and by the possible cantilever length lA from the centre line of the through track This range is marked in Figure 6.28. The position of support I on the through track is determined by drawing a straight line from support II through the contact wire~ crossing point, which lies at position BK at a distance of bs/2 from the through track, until the permitted lateral position bs of the contact wire on the through track is reached. The lateral position of the contact wire at support I on the branching track can then be defined with bmaxz - 0,55 m relative to the track centre line of the brand1ing track. If one furthermore returns from this point with a straight li11e through the crossing point to support II on the branching track, one obtains the rn11wnie11t stagg<'.r tlwre for the contact, wire. If this lies within tli<' predetermined rang<~ as shmrn iu Figm<~ Ci.29, the solution found in this manner nm be wwd as the basis fo1 fu1 t lier
PE
·~ 0,55 m
Support I
Support II
F'igure 6.30: Contact wire ranting above a point.
wind displacement If this is not the case, it must be decided from a judgement of the situation, how the crossing point or the position of support I must be altered so that a practicable solution will be possible. The wind displacement must be checked after the provisional definition of the supports and the lateral positions of the contact. wire. If non-permitted lateral positions result, it would be appropriate to shorten the span lengths between supports I and II or to alter the lateral position of the contact wire at the supports. These measures are however limited by the restrictions defined by the fitting-free area. The span length between supports I and II should not be more than 65 m to restrict the dynamic impacts on the contact line and therefore to achieve convenient. transition characteristics in the point area. The span lengths should be reduced in front of the point, while observing the specified maximum difference of the span h!ngt.hs. An example at the end of clause G. 7. 7 illustrates the crossing-type contact line w-irm.g of points.
6. 7. 7
Height of contact wires 1n points area
The contact wire on the through track is positioned below that on the branching track and is laid parallel to the track for speeds up to 250 km/h in the area of the c·rn.ssing bar. It is arranged there 10 nun higher than the nornmal contact wire heu;ht for speeds u > 250 km/h [G.9]. The inrreas<'d cont.act wire height starts and ends at the droppers adjacent. to the crossing bar. The nmtact wire on the branching track is adjusted at the crossing 20 mm higher than tltC' through track contact ,vire. Th<' c-o11t,c1ct wire remains at this height at the Collowing dropp<'.rs in the dirrction of thl' point. <'Ile! on the lmu1ching track contact. !in<' 11p to support II Drn-1.11s<' of this, tlw contact \\ ire iu the overlap mra is approxirnnt.<'IY .\() rnrn higher on the liranching track t.hatt on the through track. Figure G. :31 ill11strntcs Ille variation of the umtacl win'. lu:zy!t.f 1elative to the nominal l1rigltt or tit<' c·( )Iliad wire. Sta1ti11g front tltr contact wit<' crossing, Ll1<' co1tt c1d wire 011 tit(' IJ1 ancl1ing trnck overli<'ad li11<' in ill(' dirN·Jio11 of 1]1c' sL1ri ol Lit(' poi1tts is liftl,d 11p to ill(' 111':-::t s11pport \ritli
288
______ 6_ Plan_11ing~()f_overhead CC)11t;act line systems
150
Branching track contact wire
mm
I I I I I I I I I I I I
X
I
s
u
I I
: 30
30
I
Through~k contact wire for Re 250 : 0
-------------
I I
10
:o I
I
I
,_ _ _ _ _ _x_ _ _ _ _
~:
~-1I of
i:o
&',
OI~ ;:g1~
~I
CID
0:
8:t
I
km
X----
1
I I =1
t:
I
&: ~,
c75:
Figure 6.31: Contact wire height variation in point area.
the shape of a quadratic parabola by a further 120 mm. This gives a height difference of 150 mm relative to the nominal contact wire height of the negotiated contact wire on the through track contact line. With a dynamic uplift of:::; 100 mm, the pantograph cannot reach the raised contact wire at support I (Figure 6.31) for the branching track. In addition to an exact contact wire height, the dynamic uplift of the negotiated contact wire is transferred to the overcrossing contact wire by crossover droppers before it is negotiated. Convenient transition conditions in the points area with limited contact forces are the result. Only one contact wire may be negotiated at one time at support I with a speed v > 160 km/h. The distance :i: between the contact wire crossing and support I should permit a raising of the branching track contact wire, which guarantees that the raised support in the branching track is not reached, even as a result of dyna:rnic uplift of the contact wire on the through track. A contact wire that is raised up to 150 mm above the contact wire height of the through line is considered negotfoble in the raised state. Support I on the branching track is to be configured with a maximum lateral contact wire displacement b = 0,55 m and a bending angle a :::; 5° for main lines and a < 15° for secondary tracks. Only contact wires that are raised by more than 150 mm are considered non-negotiable in the raised state and can therefore be configured with b > 0,6 m and a larger angle than respectively 5° or 15°. This results in the position for the termination of the diverging contact wire (Figure 6. 30). The verification of the contact wire height increase y at support I is performed according to (,5.22) with the contact wire tensile force Hew in k::'-J (6.6)
with
y
G~:w ./;
H(·w
contact ,vire height increase at support I in m, specific load of the~ urntact wire in N/m, distance lwt.m'<~11 contact wirn crossi11g and support I in rn and t<>nsile. forn' of Lli<' co1tt.ad wire in N
G 7 Cont.a.cl, lirw alioV(: points
289
Table 6.5: Necessary distances
:i:
awl the specified points design. Type of Tensile force of c:cmtact wire contact wire Hew in N Cu AC-80 10000 Cu AC-100 10 000 CuAg AC-120 15 000 CuMg AC-120 27000
Specific load of contact wire G~:w in N/m G,98 8,73 10,48 10,48
between the contact wire crossing and support I Dista!lce :r
Specified points design
lll Ill
18,G lG,6 18,6 24,9
E\\ E\\ E\\" E\\
G0-1200-1:18,5 60-1200-1:18,5 60-1200-1:18,5 60-2500-1:26,5
/1= 47 50
X
18 50
....
8.50
..
PE
/
Support l!
Support l
Figure 6.32: Wiring of EvV 60-1200-1:18,5 with the fitting-free area that is valid for DB for contact line type Tie 250.
The muuttll!lll distances x for nusmg the contact wire to Li0 nun are contained in Table G.G. This height increase is possible only ,dwn t.he points geornetry permits. The points design to be used nrn be found in Table G.5. The next step is the e:w,minatfon of the lateral contact ·w11e forces at the supports, which must lie within the range 80 N < F 11 < 2500 :\J for lzyhtweu;ht steady arms. Finally, th<' opposiu12, fraud of the co:ntile'Ue:r.s and th<' frc•c·dom frum rnntact at the temp<'rature ra1112,<' lirnits is to he cxm11i11ed.
6.7.8
Exan1.ple for point wiring
Poiut EW G0-1200- l · 18,G lll \\ ill1 f !w fit,tiug-frec) an•a that, is valid for DB is to lie wired for oV<)rlt<\ad cout.,wt. li1w sysl,C)lll type H<\2GO witl1 C11:\g AC-120 (Figm<' (i.:$:Z). A wind speed 11w 2G rn/s is appli< alil<' for I It<' pc1i11t local.iou . Tl!(' dist,;111cc r \I hdw<·<·11 the intersection i\ of t.l1c! 0111.c•r l101111
290
_______________________6_Pla11r~~Yi.
(Figure 6.25) and the next midpoint anchor of the contact wire on the through track is 450 m. The existing point is located in a track connection that consists of points of the same type. The distance between the track centre lines is 4, 7 m. The processing steps are: D,istort the points: The track layout plan is to be magnified by the factor 10 as explained in section 6. 7.2, in order to add the branching track radius. This also achieves a clearer representation of the lateral position of the contact wire. Mark the fitting-free area: Draw the fitting-free area in the points layout diagram parallel to the track centre lines at a distance of 0,6 m and with a width of 0,45 m. Draw the locations for Bp, Bu, BK and B 1: The profile dimension is 1,22 rn at DB. The start of the overlapping area lies at Bu 1,05 m. The position of the contact wire crossing follows for overhead type Re 250 according to equation (6.5) at the track centre line spread BK = 0,5 bs + 0,66 bz = 0,5 · 0,3 + 0,66 · 0,3 = 0,35 m. The contact wire crossing lies at the position where the track centre line spread is 0,35 m and is spaced 0,15 m from the through track. The mark B1 for support I with a distance x = 18,5 m rounded to the next half meter results from the minimum distances between the contact wire crossing BK and support I in accordance with Table 6.5. Determination of support II on the through track: Support II is to be positioned on the through track such that the contact wire fitting does not move into the fitting-free area because of temperature-dependent length changes. Profile clearance should also be present relative to support II on the branching track and from the branching track relative to the support on the through track. This is at least the case at a distance of 4,5 m from the intersection point A at position Bp. It is added half of the distance between the cantilevers at support II with 0,6 m and obtained initially the pole location with ls Ks, rounded to 5,5 m. It is expedient to place support II on the through track so that the contact wire stagger is zero. Determination of support I on the through track: A straight line is drawn from support II on the through track through the contact wire crossing to marker B1. The contact wire support point I is obtained on the through track with a stagger of 0,2 m for the span length li = 47,5. Determinat'ion of support l on the branching track: Support position I for the branch track follows at the location of the already determined support I on the through track at a contact wire stagger of 0,55 m relative to the branching track. Determination of support II for the branch:ing track: A straight line is drawn in the direction of the end of the point from support I through the contact wire crossing. Support II is obtained for the branching track at the intersection A with the line B-C with a contact wire stagger 0,10 m. Position C marks the permitted stagger of 0,3 m for support II on the branching track and a profile clearance Bp. Support II on the branching track can lie only between the position B and C or on a parallel line in the case of a larger profile dimension BF. Examination of the wiring parameters: The examination of the span length shows that the resulting span length l 1 47,5 m is less than the limit span length of 65 m. Undesirable contact forces in the area of supports I and II are not to be expected. Support II on the through track may not nt0V(! into the fitting-free area. Its travel for this effect is examined . This is dependent upou tlw distance between Support II and intersection A of the <~xtcrnal boundary of' th<~ fit,ting-fr(~e area with the track centre
Q?
Contact. line al>ovnyoint.s
291
___ 40.00 [9~.-;-·--------1_1_5_0_0_0_ _ _ _ _ _ _ _ _ _ _1-,,___ _6_0_0_0_ _--i
19 00
10.00
N N
-
0 30
12
/ Support II
Support I
Figure 6.33: Corrected wiring of EW 60-1200-1:18.5 with the fitting-free area that is valid for DB for overhead contact line system type Re 250.
line of the through track, in the example support II is 450 m from the nearest midpoint anchor, the coefficient of expansion a = 17 · 10- 6 K- 1 and half of the temperature range (for overhead contact line system type Re250 619 = 50 K). The travel Lw for support II on the through track is Lw = L · a · 679 = 0,38 m. The movement of the contact wire fitting at support II on the through track is with 0,38 m much smaller than 6.LsKs = 4,5 u1. Travel at support II on the branching track can be ignored for the shorter overhead line length on the branching track. Both contact wires at marker Bu must be arranged in accordance with Figure 6.24. This is the case for the cielccted contact wire Ktaggers. The requirement that only one contact wire is negotiated at support I is satisfied. The distance x between the contact wire crossing and support I is 18,5 m and corresponds to the value in Table G.5. E:carn.'inat,ion of the wfrui rhsplacement: The examination of the wind diKplacement gives the dashed line shown in Figure 6.32. The contact wires on the through and branching tracks move r;111diing liuc is fotllld at position C. Tit<) sp,111 il'11gt 11 /, 1 i11c l<'ilS<'s I():)() 111 wii.11 Lil<' displ,1cc•111<'11I nfsuppmt II
6 Planning of overl1:_ead c:ontct~t line s_ystems
292
Support I
Support II
54,0
55,0
51,5
54,5
1--------1--------.i--------·-----1--------60-3000/1500-1 20 tb
Track centre line Fitting-free space - - Contact wire route
19,3
-200
PS
500
60-3000/1500-1 .20 tb Support II
Support I
Figure 6.34: Typical wiring of a transition connection with the fitting-free area valid for the Norwegian main-line railways.
track from position D to position E. Support II on the through track is also displaced 50 m on the span length. The contact wire crossing position is displaced slightly in the direction of PE and lies 0,15 m from the through track centre line for the selected variant. This satisfies the requirement 0,5 bs. The crossing position lies at a distance of 0,20 m compared to the branching track centre line. The branching line contact wire does not violate the permitted range emax in the area of the contact wire crossing. Examination of the horizontal forces: The observance of the horizontal forces of the contact wire at the supports I and II can be examined with the aid of equation (6.1). The following horizontal forces in N at the supports for the selected wiring lie within the permitted range 80 N < Fr-I < 2500 N. Through track Branching track
Support I
Support II
159,5 379,5
128,2 317,2
Figure 6.33 shows the described contact line -,.,iring of point EW 60-1200-1:18.5.
6.7.9
Tangential point wiring
The tangential wiring of points consists of the parallel routing of the overhead contact lines in the overlapping an!a with contact wires approaching the pantograph from above and not from the side. The French National Raihvay (SNCF) employs simple tangential wiring consisting of two overhead lines for lovv priority tracks. Dependent upon the type of points, the range P is det<)tt11i11ed c1nd thus the location of pole B as shown in Table G.G and Figure G.~~~L
293
Table 6.6: Dirnew,io11 P defined the area of location fen- support B (Figure 6.35).
Type of point
EW EW EW EW EW EW
Support B
Support A
I
,_ I
-
0
~-
0
lZ2J
60-1200-1:18,5 60- 760-1:14 60- 500-1:12 60- 300-1: 9,4 60- 300-1: 9 60- 190-1: 7,5
-
---
Point angle tann 0,054 0,067 0,083 0,106 0,111 0,133
Dimension P mm
± ± ± ± ± ±
4,00 3,30 2,30 2,00 1,80 1,50
Support C
-
PS
Area for support B
I
--p---1 . . p ... PC
Figure 6.35: Simple tangential point overhead line wiring without auxiliary overhead line.
Triple tangential wiring consisting of three overhead lines is employed on high-speed lines. An additional overhead contact line, also known as an ;:tuxiliary overhead line, takes on the task of guiding the pantograph in the area of the points as shown in Figure G.36 in a similar manner to the pantograph guidance in overlaps. The non-intersecting wiring of the contact lines in the area of points used with tangential overhead equipment does not require a crossing bar and thus reduces the contact line mass in a dynarnically desirable manner. This mass reduction is however cancelled out by the very unsatisfactory negotiation of two contact ,vires at the support. The tangential wiring of points requires corresponding length developments to be able to raise am! lower the contact wires. These conditions are not present with the employed points ( Fig me G. 3G) iu many eases. The investment and mainteuauc<' costs are increased by the provision of au additional overhead line at the area of the point and adjnstmeut efforts arise during faults. SNCF t\1t1plovs pantographs with a total width of 1430 mm and a contact strip width of 800 rnn1. Bv rnrnparisou, DB employs pantographs wit.Ir a total width of 1930 mm and a working widtl1 of' 1-130 mur. Tang<'ntial wiring of points is no! possible at DB (6.9], dire' to I Ji,, diffou nt pcwtogntplr geomd.ry. Exp<\tir.11cc ,llso shows that tangential wiring is !101 ll('('('SSi\l\' 1
GPla.1111ing of overhead contact line systems
294 36-9
40,5
45,0
1
---- 0,37
j_Q,44
0,2§!_
c5
- -- -
36-10 36-12 _ _______3_6_,o_ _ _- - i
.... ___1-1_~2_ __ _
>
0,10[_,,,__
_
I0,52
0,261
j
i
i
0,24
0,15
Negotiated contact wire Non-negotiated contact wire Track centre line
I
1-----------
0
0
0
~I~ ~ 0 II Q)
II
Q)
II
G)
Catenary wire
_j_/__
1-----.-1- - - - - ' - - - l _ _
'.'.3-1;
l'::II ________ _
Portal
I (')
2
I
__!__ _ __
~I
~I
Q)
Q)
~ I Negotiated contact wiW I
I~
Cg)
Catenary wire
: ---__,__l_ _ __j__/_ _ _~ - -
~0------------0+-----I I:3I I
~I ~I
~I~
£ I !!_
Negotiated contact wire
~1~_1_ _ _ _ _ _ _ _ _ _ _~71_ _ _ _ _ _ _ _ _ _0)71 ______
~L~~---------_J_,---____________
®
Catenary wire 0 10
0
LC)
0
~
~10 II
Q)
11
C\l_
II
~
g_1 ;:? ~
ci
II I ~ II Q)
1--
-----
~I
£1
~I Negotiated contact wire
111 Q)
Figure 6.36: Tangential point wiring with auxiliary overhead line for a high-speed point tg 1:65 on the SNCF Atlantic line.
6.8
Route obstacles for wiring
6.8.1
General
Ro'U,te-related constrm,nts for overhead ccmtact line systems are points, signals and signal visibility, railway crossings, building structures that inihwnc<' pole locations and ekctrical sectio11io11g.
6.s nouteo1istac10-s for· wir:ing
6.8.2
Points
The locations of overhead line poles at points are correlated to certain positions. The possible locations of supports in point areas are handled in clause G. 7.6. During planning points can be displaced with the consequence of necessitating alterations of pole locations. Then, adaptations of the wiring are atternpted by changing the neighbouring span lengths. If this is not successful, moving of the supports in the point area is possible within certain limits, which avoids renewed wiring of the affected point. Observance of the minimum clearances between the support requirements at points and crossings and the supports needed for other electrical switching groups must be examined. The required minimum clearances can usually be realised with small support movements. The supports allocated to the individual tracks need not be located opposite to each other at track connections between main lines.
6.8.3
Signals and signal visibility
Signals require a minimum clearance between the signal pole and the overhead contact line system pole. This is 10 m at DB. Minimum electrical clearances of 1500 mm from energised components of the 15 kV overhead contact line system and earthed signal components are also to be observed. Unhindered line of sight for the traction vehicle driver to the signal is a safety requirement for railway operations. The overhead line poles are to be located in such a manner that they permit uninterrupted signal visibility of 300 m to the approach signal and 500 rn to the main signal. A verification of the signal visibility must be made. Short duration covering of the signal by overhead contact line components such as cantilevers, steady arms and insulators is permitted and does not require verification of visibility.
6.8.4
Railway crossings
Grade level crossings permit speeds up to 160 km/h on main lines. Safe use of railway crossings by road traffic is to be guaranteed during the planning of the overhead contact line system. The necessary drive-through headroom and, if necessary, the profile c:leara.nce for heav,· load transports is to be provided (see clause 8.G). The poles adjacent to the crossing are to be arranged symmetrically to the raihvay crossing. The contac;: wire supports are to be placed in such a manner that the contact wire sag permits the passc(qe of vehicles under all th<)rrn,d and dynamic effects, including ice loads. Th<' span length influences the maxirn111t1 sag at the centre of the span at the railway ('J'OSsing. Railwav traction power lines that intersect with crossings arc to be suspended at, such a h<'ight that. the millimum r:leo.rn.nc:rcs /;o enc·1:1J·isfd parf;s of the overhead contact line and thr traction powrr lim~s. uud<'r tit<' 111,1.ximurn sag experienced at the highest ('Ouductor teinperatme, is observed in ,Kr·ordanc<' wit.Ii clause G. 11.1. If th(' standard heights n'qllir<'d for th<' contact wire aud t.ractio11 pmvcr lilies cannot IH' l'1dlill<'d. t.llf't1 J>rofifr, 1111,/.c:s nr<' to IH) prmided at hot It sides of tl1e rail\\'ay nossing (S<'(' ("L\l!S(' 8Ci 1)
6 Planning of overhead contact line systems
296
Table 6. 7: Air gaps according to EN 50 119. DC 0,75 kV DC 1,5 k\ DC 3,0 kV Air gap Static in mm Dynamic in mm
100 50
150 50
100 50
AC 15 kV
AC 25 kV
150 100
270 150
Contact wire Minimum dropper length Minimum contact wire height
Top of rail TR Liftin reserves
Figure 6.37: Minimum clearances applicable in case of reduced overhead contact line system height.
According to BO Strab, clearance from the road surface to the energised parts of overhead contact line systems on urban transportation lines, operating at up to DC 1500 V and AC 1000 V, is to be at least 4,7 m. This headroom can be reduced to 4,2 m under structures. Signs in accordance with the road traffic regulations warn of the headroom restriction. The height indication on the warning sign is to state the actual clearance less a safety margin of 0,2 m.
6.8.5
Engineering structures
Space is often not available under existing bridges and other engineering struct-ures for the installation of catenary-suspendecl contact lines without restrictions and special civil engineering measures. Bridges and structures from obstacles for wiring overhead lines, since the pole locations cannot be selected freely and the wiring must be tailored to suit the individu2,~ structure. The arrangement of overlapping sections under bridges is difficult. Compliance with minimum clearances between energised parts of the overhead contact line and the structure and between the contact line and the top surface of the rails must be verified during the design of overhead conta.ct lirw systems under bridges or other structures. The overlap to the nearest energised pa.rt of the overhead line can be determined from the bridge data, such as headroom, width. crossing angle, inclination of the bridge in parallel and laterally to the track and the profile of the underside of the bridge. The air gaps sp<\cified by E>i GO 119 are listed iu Table G. 7 For DB a clearance of ~mo rnm is valid for th<' static r:leo.1unce between the energised parts of tlw ov<,rhr~nd contact, litt<' s\·st<'lll ,rnd t lt<' strnd.mc• If t lu, miuirnurn clearance
6.8
Ro~1te obstaelcs for
wiri~1g
Bridge superstructure
~
Bridge span
Transition span
Centre spans
Transition span
Standard span
Figure 6.38: Arrangement of transition and centre spans at overhead contact line system height reductions.
S as shown in Figure 6.37 for standard contact wire and s~·stem heights cannot be achieved, then as a first step, the catenary wire can be lowered by reducing the span lengths. A limit occurs when the minimum dropper length is reached at the centre of the span (Figure 6.37). If this is not sufficient, a bridge reconstruction can be avoided by lowering the contact wire to the minimum contact \\·ire height. The contact wire height should not be lowered below 5,15 m, considering all influences, with regard to freight transports with loading gauge violations. If a further reduction of the system height is necessary, then sliding droppers with an installation height of approximately 70 mm can be employed instead of standard droppers. HoweYer, this will result in a reduction in the overhead line elasticity. Uneven wear of the contact ,vire can occur as a result of the uneven elasticity. Sliding droppers are therefore only suitable for speeds up to 120 km/h. Further possibilities for reducing the installation space for overhead contact line systems exist in the employment of double or triple contact \\·ires without a catenary wire. Only small uplifts occur due to the reduced elasticity of such m·erhead contact line systems. For low bridge structures, the catenary wire can be earthed in the area of the structure, anchored to the structure or lowered to contact wire height and routed through the structure as a second contact wire. Under extremely cramped conditions, neutral sections can be inserted into the contact line on each side of the bridge structure. The earthing of the contact wire achieved in this manner permits the restriction of the clearance between the contact wire and the structure to the dynarnic uplift plus a mechanical safety clearance. It is however necessary to operate the traction unit main circuit breake.r ea.ch time such a bridge is passed. If such special constructions are not sufficient, it. is theu necessary to lower the track, raise or reconstrnct the bridge. \rVhcn mini1tllllll clearances between the bridge and energised sections of the overhead contact liuc cm\ e!llploycd, Hashovcrs caused by birds und<'r the bridge or the formation of icicles in winter occm frequently and lead to overhead line disturbances. The catenary wire sl10llld lw protected by a shrink-on insulating sle(\\'f' to en oid this. Wear of t.lu· r:0·11Jru:/, wire is to be ronsiderc~d during wrification of the clearance. Wear of 20 % 0I1 th<' couiact wire reduces the load of tlw contact \\ ire OIi the catenary wire ;111d l<'ads io vat<'d catC'nan· wire position. Saf<'t\ d<'arnnce may not be viobd<·d 1111d<'1 ! liis rnwlition.
~6 Planning of overhead contact line systems
298
Table 6.8: Gradients for contact line height reductions [6.6]. 'Vn1ax
km/h 100 120 160 200 250
Maximum gradient in transition spans 1 )
Maximum gradient i 11 centre spans 1 )
1 l 1 1 1 1
1 1 1 1 1
: : : : : :
400 500 600 800 ( two spans before the bridge) 1200 (span before the bridge) 1000 ( two spans before the bridge)
: : : : :
200 250 300 500 750
1) see Figure 6.38 I= 45m
a= 15 m
~I-
Contact wire
--------/
__ ,,---,,,,
~l ~i I :;j
_§
'
________________ :~-~-=--'-------------------------.§'i+'
i)
Contact wire with ice load
£
Gf
TR (top of rail)
Figure 6.39: Determination of the clearances in the bridge span of a reduced height overhead contact line system.
Once the heights and supports for the contact line under the bridge have been determined, then the layout of the contact wire gradient in the neighbouring spans may proceed. Differentiation is made bet,veen transition and centre spans (Figure 6.38). Dependent upon the permitted speed Vmax, the maximum gradients in the transition and centre spans are to be observed for the DB overhead line types as shown in Table 6.8. The lowest point of the contact wire in any of the transition or centre spans ma,· not be lower than in the bridge span. Example:
Reference data (Figure 6.39):
Length of bridge span l Headroom of bridge LH Bridging width U Crossing angle between str11ct,urc~ aucl track (1 Distance between the ovii 1
45,0 m
6,1 m 15,0 m goo 15,0 m Re'. 200 11,0 N/rn
6.8 Route ~)!>stacles forwiring ...
Standard system height SHs Standard contact wire height CWH Speed of travel v
1,8 m 5,5 m 200,0 km/h
Wiring with standard contact wire height, spanlength 45 m: Catenary wire sag at midspan of span under the bridge fcA = l 2 · G~m)(8 · HcA)
= 45 2
m
2
·
14 N/m/(8 -10000 N)
= 0,35
m
Determination of the catenary wire sag fx at point a = 15 m fx = 4 · fcA ·a.· ([ - a)/l 2 = 4 · 0,35
lll ·
15 m · (45 - 15) m/45 m 2 = 0,:H
Ill
Determination of the existing clearance Sv to the bridge
Sv
LH - (CWH
+ SH
fx) = 6,1 m - (5,5 m
+ 1,8
m - 0,31 m)
= -0,89 m
Reduction of system height: System height when using flexible droppers with a minimum length ln min = 0,5 m lnrnin
= 0,35
Sv = LH - (CWH
+ SH -
SH= few+
m
+ 0,5
m
= 0,85
m
fx) = 6,1 m - (5,5 m + 0,85 m - 0,31 m)
0,06 m
Since Sv < S, a reduction of the contact wire height follows in the next step. Reduction of the contact wire height: A minimum clearance to the bridge is given with the contact wire height at 5.2 m
Sv = LH
(CWH
+ SH -
fx) = 6,1 m - (5,2 m + 0,85m - 0,31 m) = 0,36 m
Since Sv > S, the specified minimum clearances can be achieved. The employment of sliding droppers is not necessary. Determination of the contact wire gradient in the neighbouring spans:
The contact wire heights for the neighbouring supports are to be determined with reference to the permitted gradients set out in Table G.8. The objective of v;.1rving the contact wire gradient is to produce a sinusoidal form for the contact wire height giving a constant vertical acceleration of the pantograph, especially in the transitions to the horizontal. The system height SH is to be raised uniformly along the contact wire height to achieve a continuous increase of the elasticity. A longitudinal profile as shown in clause G.11.3 depicts all relevant data for the overhead contact line system height reduction to scale. At speeds higher than 2:30 klll/h, increased contact pressmes in overhead line height reduced sections caus<\ the dropp<\l damps to tilt, whicii can lead to ovnlwad line disturbances. This is also one of tlw reasons for the a,oidance of plaun<'d contact, line wire height reduetious at speeds greater thau 230 km/h. I?azlwu.y /Jr·idges also form rnnstraiuts to pole positiouiug. HiglHT wind loads require shorter span lcugths . Poles arc positi01wd a.how bridge pins for mchit<~ct.11ral and technical reasons. These r<\
300
G Planning
Figure 6.40: Pole foundation on bridges.
6.8.6
Electrical separations at stations and on open track
Electrical separations form constraints for wiring. This applies especially to insulating overlaps, which are arranged between stations and the open track, and to phase and system separation sections. The position of overlaps is determined in the early stages of overhead contact line system planning, taking into consideration signal locations, station entry points and the circuit diagram. Insulated overlaps separate the overhead system into open track and station sections. Section insulators are also constraints at positions specified in the circuit diagram. They influence wiring especially at point connections. Overlaps and section insulators are not to be located in track sections at platforms.
6.9 6.9.1
Layout plan Objective and information
The track layout plan, which contains the track layout and information described in clause 6.2.3, is us
6.9.Layout.plan
301
traction power supply lin<~s and cables, discom1ectors with number, op<~ and short circuit indication device, disconnector lines with co1111ection and intermediat<\ insulation, areas with co11tact line height rcductio11s, clearances at level crossings, signals for electrical operatio11s and comments and u~rminology. The ad_justn1,enf; diagram shows the muting of the overhead contact line system to a distorted scale_ The stagger of the contact wire and th<' system !wight can be seen in addition to tlw type of support. It assists re-installation and re-adjustme11t of the contact line after fault situations. The earthing diagram shows all items of equipment for the return curre11t circuit, such as longitudinal and transverse rail bonds, transverse track bonds, react.a.nee coil joint bonds, diagonal bonds, z-bonds at points, return current cable and conductors and the protective earthing, such as all bonds between rails and poles and - conducting parts of equipment, which lies within the zone of the overhead contact line system, but does not belong to it. The contact hne layout plan is used to show the earthing system on the open track The layout plan with a scale 1:500 or 1:1000 should have an easy to manage format, if possible with the height of an DIN AA sheet. If the wiring of the open tra.ck and the station is distributed over several sheets, then the overlaps of plans are to be arranged so that no repetitions occur.
6.9.2
Overhead contact line system symbols
All components are represented in the overhead contact line system layout plan using overhead contact line sym.bols. T~1.bles G.9 to G.lS illustrate the symbols emplo)-ecl by DB for the contact line, cross-span elernents, poles, soffit posts, traction pcnn'r supply lines, discormectors, traction current return circuits, protective earthing and other equipment.
6.9.3
Contact line equip1nent supports and pole locations
T'lw 1·0·11.t.ad lm,e c1rmp111,e11t s'tlJJfJo·,ts, ddincd as at.t.aclittient local ion of th(~< orttad. wire fit.ting 011 the contact \\'ire. can lie dct(~rn,incd frn111 t lie rnttlad wire layo11t.. [11itially tit<' cot1t.,1ct. wir<' layout at rn11strni11t.s is ddincd and t lie ittt <'rtt1<'diatc' sec! ions follow witlt I ltc has(~ data as in d,uts<' G.J. Th<' local /:rad: ln1;011/., t lw conditions ott tlt<' SlljH'I st rnct llr<' and 1<'qlli1 cttH'1tts for lll<'cli<111ical S<'{li\lilf io11 of' t l1c• m<'ill<'ad c-0111.ac( lit!(' S\S{<'lll d<'l<'rlllitt<' 1lt<' I \'j)(' of Slip-
302
6 Plm111ingof overhead contact line systems
Table 6.9: Overhead contact line system symbols. Designation Track with overhead contact line system Track without overhead contact line system Track with planned contact line system
Symhol
-
-
fixed termination
.-+--
Overhead line system with tensioned catenary and contact wires automatic-tensioned termination fixed termination Overhead line system with tensioned catenary wire and twin contact wire automatic-tensioned termination fixed termination
Planned termination
Midpoint
Midpoint anchor at head-span structure
6
--- -------
~
fixed termination
Designation
--- 6
Overhead line system without catenary wire automatic-tensioned termination
Overhead line system with catenary wire automatic-tensioned termination
Example.
~
.___ ~
"4--tl--
~
~
~*(iii>
)(
)(
-· -
- - -
Midpoint anchor in tunnel with anchor to the ceiling Midpoint anchor in lunnel with anchor to the wall
Symhol
A\
7t
A
Lt
Crossing overhead lines pro vided with a cross-contact bar (negotialed crossing)
~
(Xl
~
Overhead lines cross double point with clamped contact wires
<>
~ ~
~
Electrical connection between catenary wire and contact wire
----.~e ----x
X
Overhead lines cross without touching (without cross-contact bar, nonnegotiated crossing)
Electrical connection of two lines
Example.
(Xl------
_::::::::::--;-
----<>
C r,
0
6
6
Section insu1ators
-u-
~
Intermediate insulation in contact wire and/or calenary wire or cross-span wire
-¾-
~
Bracket between two conlacl wires (compression and tension)
~
Contact wire-conductor connection without insulation
--{)-
:)- -
64*~- 6
Contact wire-conductor connection with intermediate insulation
-lf-- -
'f-- - - -
~N I )\!( I
Overlap
t
\I
t
i
t
ITT 78 /\40
-
8''l/0 640 Cl
Con\acl wire stagger
-
~
6.9 Layout plar.1 ....
Table 6.10: Transverse support element sym- Table 6.11: Symbols for poles and soffit bols. posts. Designation Cantilever for one track on pole
Two cantilever on pole
Cantilever across two one tracks
Pull-off for one track
Pull-off for two or more tracks
Symbol
I
II
~ -----
Support in tunnel on wall with one steady arm Support in tunnel on wall with two steady arms
!l
6
/1
t
y
Portal
Support in tunnel on wall without steady arm
6
J
---
Twin cantilever support on a wall
Symbol
Double-channel pole
Head span suspension
Tensioning portal structure with intermediate pole
Designation
Example
0
8
--t-~+· jo •
·I
I • I I I•
Double-channel pole on bracket
0
6
6
0
~
~
Lattice steel pole
•
Lattice steel pole on bracl
.,
• • J.
J.
@
~
~
@)
~
()
~
Concrete support pole
Concrete tension pole
Wooden support pole
Wooden tension pole
00 H-bearn pole
---!!
Example
@
~ ~
Anchor
1
l
1
l
I
/
0
~
~
-l Pole with wheel protection
1
~
\ /
6 \
So/fit post in tunnel on a wall without steady arm Sotfit post on ceiling in tunnel with one steady arm Soffit post on ceiling 1n tunnel with two steady arms
!
6 I
6 I
~
I
I
b
304
G Pliu111ing_ofoverhead_contact_line systems
Table 6.12: Symbols for traction power lines. Table 6.13: Symbols for disconnectors. Designation
Symbol
Traction power line
---
(e g 2 reinforcing line
Example of application
feeders E-AL-240) Planned traction power line (considered in design) Traction power cable, e g 15 kV cable
---
# [-AL-240
Designation
Symbol
Example of application
DisconneGtor - open
'6
_6_____
-fl [-AL-240
Cu 95 - - - -+----2
Disconnector - closed Disconnector. - with earth contact
(e g Cu 95mm2) Traction power line
D1sconnector
6
I
cross arm Single suspension
EHL
I
with strap *) Double suspension
EHL
Disconnector - with hand operated
6
D1sconnector - motor-driven, for 1000 A,
6
V-suspension
0
locally controlled
6
I
D
Disconnector
V
V
mechanism, square key
--
DH
DH
I
/\
- with hand operated ~ mechanism, triangular key
- motor-driven, for 1000 A, remotely controlled
Traction power line termination at pole
~
Termination at traction power line cross arm
~
~z:_ Disconnector
~
- motor-driven, for 1700 A, remotely controlled
Termination at cross arm for switching lines*) Double termination at traction power line
--.i
e
- OT
r
~
cross arm
~
T
Disconnector - motor-driven, for 2000 A, remotely controlled
Double termination at cross arm for switching
-#I
e
Disconnector
~OT
- motor-driven with short
lines*)
circuit indicator *)
Intermediate anchoring at traction power line cross arm *)
-
T-
~ ~
T
~
= Des1gnat1on and symbol used by former Deutsche Reichsbahn
Switching transverse line cross-arm ~) Control cable (e g 3 core 1,5 mm 2)
0
0~
---1-t5__ _ .3
Circuit breaker
*)
Designat on and symbol used by former Deutsche Reichsbahn
6.9 Layout plan
305 ------------------------- ------------
Table 6.14: Symbols for traction return cir- Table 6.15: Miscella.neous symbols. cuit and protective earthing. Designation
Symbol Example
Designation
Rail longitudinal bond ')
Earthing plate
I\ Rail bond*)
'
I \
J
3
::J
=i
Track transverse bond*)
$
Electrical complementary
f
signal with/ witr1oul
between rail and equipment ") Rail bond for single-rail insulated tracks *)
Central switching section
r
d
3
j
Right rail insulated*)
£
boundary
0
£
Substation boundary *)
Connection line connected to right rail *) Connection line connected to left rail*)
r r r t= 0
0
Insulated rail joint in the left rail, insulation runs in direction
£
r
0
-
Maintenance boundary X
X
X
Current transformer
Location of railway X
earthing fixture Location of live-
X
line tester
of increasing stationing *) Insulated rail joint in the right rail, insulation runs in direction
L
0
of increasing chainage *) Insulated rail joint in the lelt rail, insulation runs in direction
-
X
*)
0
-
X
...J
0
....
X
Insulated rail joint in the right
Voltage limiter
ffi
*) -~ Designation and symbol used by former
Deutsche Reichsbahn
fixture (only for rescue train)
7
of decreasing chainage *)
T '
~
~
rot
ct ~
Location of earthing
of decreasing chainage *) rail, insulation runs in direction
i.:::--:;;g
E:--3
Pothead
0
a UwfUw2
Left rail insulated *)
£
Example
Ja.
Transformer
directional arrow Connection line
Symbol
~
Designation and symbol used by former Deutsche Reichsbahn
306
6 ~I_anning of overhead contact line systems
porting element such as single cantilever, portal or pull-off. The location of poles must consider the type! of superstructures, underground cables and pipes, trough channels, traction power lines strung on the overhead system poles, with minimum clearances from objects and the subsoil conditions. In case of double track lines, facing pole locations are the objective. The supports associated with points can lead to staggered pole locations at switch connections. The poles in curves on single-track lines are to be planned, if possible, with the poles on the outer side of the curve. The span lengths, which designate the distance between the adjacent cantilevers at their central position, are to be entered in the layout diagram. The layout of the overhead contact line system, the contact line supports and the poles are to be represented in the layout diagram using the symbols shown in clause 6.9.2.
6.9.4
Single poles
The arrangement of single poles along the track is determined by the required location of the contact line equipment supports. Standard lateral distances between the track and the track side of the poles (dimension TP) should be used where ever possible. Thus allowing the use of standard cantilevers ·with resultant investment savings in erection and maintenance. The standard distance results from summing the half-width of the track sub-ballast footing, the width of the trough channel to be laid in front of the pole, if any, and from construction tolerances to be considered. For example, this standard dimension TP is 3,7 m for DB high-speed lines. The maximum structural dimensions of cantilevers limits the distance of poles from the track. The vehicle gauge envelope, with extensions in curves, limits the proximity of poles to the track. The minimum clearance between pole foundations and the track is determined by summing the half-width of the vehicle gauge envelope CC being 2,5 m, the construction tolerance of 0,05 m and the margin for the curw effect on the inside of the curve. The vehicle envelope gauge must also be considered during the arrangement of poles between tracks. In stations where overhead contact line systems are to be separated mechanically, pole aisles between the tracks may be necessary and these will affect planning of the track layout. Poles in the station area and in front of platform approaches should not hinder passenger movement. Pole anchors and flexible tensioning devices are to be avoided in these areas clue to risk of accidents. Overhead lines on spur tracks are to be continued beyond the spur track and, if possible, anchored at the next O\·erhead pole. It should be noted that poles can be providc\d only 20 m beyond the end of the track or outside the standard g;-u1ge:. Various snnhols are used 011 ov<'rheacl diagrcuns to represc!nt registration arms in tunnels and pole's. such as lllid-point, pol
G.9 _Layout plan
6.9.5
307
Head-span structures
The distance between !wad-span poles and the track is variable. The use of head spans requires that all overhead contact line wiw supports to be arraugd, at the bead-span arc located a.t the same l011gitudinal t.raek co-ordinate. Pole aisles, such as required for single poles, are not ll(n~ssary. Head span lengths arc not limited from the technical point of view, but should be restricted to approximately 80 m for practical reasons. Crossing loading platJonns with head-span structures should be avoided. Head-span poles permit the t.crmination of overhead contact lines. It can however be expedient. to provide separate termination anchor poles in order to shorten overhead lines or to avoid sharp bends and intersections.
6.9.6
Multiple-track cantilevers
Mu,ltiple-trnck cantilever.s span a maximum of three tracks. The contact wire supports to be accommodated are to be arranged at the same co-ordinate. The overhead lines supported by multiple-track cantilevers are considered mechanically separate from each other. As with head-span structures multiple-track cantilevers can be positioned more flexibly prependiculary to the tracks.
6.9.7
Portals
Portals have a similar function to multiple-track cantilevers. They perrnit greater umnbers of tracks and widths to be spanned, but are restricted to a maximum leugth of about 45 m for structural reasons. Portals can also be arranged obliquely to the track centre-line, in the same way as head-span structures. Portals offer advantages at point crossovers of high-speed lines, since they can accommodate overhead c-ontact line supports that cannot be carried by single poles and simultaneously allow mechanical separation of overhead contact lines.
6.9.8
Tunnel supports
The selection of tunnel sv,ppm-t., is determined by the tunuel cross-sectiou and ceiling height. The type of support 01 head-span equipment. such as elastic S'llfJl!Or-ls or cantilevers is selected to suit the m·,tilahle headroom and the requirerrwnt.s sp<'cified for the overhead contact li11<' svstr111 Th<' arrangement of the supports lict.wee!l t l1<' tracks or 011 tlw t11n11cl wall iufluc!UC-<'s their d<'sign.
6.9.9
Electrical connections
Elcctr·i,w.l co·n:11,eduYns pro, id<' a <·111r<'llt-<·;-1rryiug bond het.wceu the! c-011!.,w( \\ 1n· attd Llw cateuat'\' wir<', bctwcC'll Lwo m·c•rlic,1d crn1Lc1ct. line li1t<'S or bet \\('<'ll ,111 o,·<·1!1<'ad co11Lact. lin<' li11<' ,llld 7Jarn.lld /1:l'.d('fs_ Tli<'\ prm id<' dditt('d rnttll('<"I iuns IJ('I W<'<'II t rossing <>,cti1ead lines M. poi11ts 01 IH'l\1'<'<'11 It<'goti,tl<'d ,l!ld 11011-11<·goti,1l<·rl O\('IIH·,Hl <01Iiact
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earth rail
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earth rail
Station
t ----------±----....._ _________
insulated rail
track reactor Poles
d) insulated rail
earth rail
insulated rail
track reactor - - - Traction return current of track /T Rail current / R
Figure 6.41: Track release circuits (a) with single-rail insulation, (b) double-rail insulation, (c) transition from double-rail to single rail insulation and (d) special reactance coil joint.
lines such as in overlaps or neutral sections. In the event that the catenar~- wire is interrupted under bridges, the provision of an electrical connection before and after the structure serves to distribute the current load. The same applies to the installation of additional electrical connections near earthed structures, such as signals and interlockings. The installation of further electrical connectors is expedient in sections with high electrical loads drawn by electrical traction vehicles, for example on steep gradients. The Z-connecting betwe<)ll tlw c:atenary wire and the contact wire fulfils the function of an electrical conn
6.9.10
Return current circuits and protective earthing
1\!tf)asures for the t.nwl iu11 ·1!'/:11:rn r:unr:11.t ri.rcui.ts and thP vmtec/.11:e crL·rtlu.ng of struct11n•s nrnst be ddi11<'d iii deli1il d1i1 ing I li<' plcrnui11g or tit<' O\"
\
6.9 Layout plan
Bonding to connect x) insulated rail xx) not insulated rail
309
Feeding
Figure 6.42: Track release circuit of a point.
The details are to be included in the planning documents and especially the earthing d'tagram. The specifications resulting from the various designs of the rail insulation relative to the sleepers are to be taken into account. It is possible that either both rails of a track are not insulated relative to the sleepers, one rail is insulated and the other not insulated or both rails are insulated relative to the sleepers (Figure 6.41 b), corresponding to the requirements of the track release system. The extent to which insulated rail joints are provided in the rails, is dependent upon the design of the track release circuits. In the case of track release circuits with frequencies of 100 Hz or 42 Hz, as employed on DC systems, the insulated rail joints provided, must be bridged using reactance coils. In particular the insulated r-ail Joints in points and in stations should be considered during the design of the traction return current circuit (Figure 6.42), since single-rail insulation is mainly used there. \Vhen audio frequencie8 at 16 kHz or 10 kHz are employed for the track release circuits, S-shaped rail bonds form the boundaries of the individual track release sections. In this case insulated rail joints are not provided on open track. Track release circuits can also be used for rail failure detection, consequently the rails can only be used for railway earthing in accordance with theses systems.
It is the planners task to design in detail the measures necessary for a safe traction current retu7"n aud rnilway earthing. The fundamentals are specified in EN 50122-1 (6.10] and German railway directive [6.11]. All rail joints are to be documented during the inspection on foot and to be provided with longitudinal connectors consisting of copper cables. The bonds between the rails of the individual tracks and between parallel tracks are also to be configured. The rail and trnek bonds rnust generally consider the track release circuits. Ia audio frequency track circuits, snch bonds arf~ found at the ends of the track release circuits. Rail and track bonds ar<' to be recorded in the layouts using appropriate symbols. The configuration of the 1d1l'fn current wn:nectfons to the substations is an i1npo1tant aspect. The rail and track bonds at tlt('.SC locations are to be designed to suit the total currents. The specifications of tlw track release svsteu1 c1rc to I)(' c-011sid<'t<'d during th<' iutcrttteshing of' st.ations or points. One rail i.-; oft.en d<'fi1l('d ,ls Uw <';-ltt h rail in this area, which can ltowevc.r cha11g('. from Oil<' rail to anot!1n. Tlw bonds !wt\\"('('!! the i11cliviclual rails c\t(' to lH' configlln'.d COtT('S[)OIHling t.o the a1 r,utg<'lll('tlt ol t lt<' <'.arth rails. In priuciple, t lw prnt.ective cart.l1i111-', can IH' nutd<'. di1 <'< U\· to tit(' <';111 li mil in AC systems . 'l'l1<' n11ntlH'r or <',ullt 1,onds is r<·stricl.<'d h\· sp,1ci11g i11t<·1\rtls (II <1pp10\:i1n;ll<'h· :iOO tu .,1 1
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310
·---- -·----·--· ___ ---········-·-··-- 6 Planning of overhead contact line systems
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G.9 Layout plan
311
with track rd(:asc systems that arc also used for rail-fracture detection. All strnctures to be incl ud(~d in the earthing arc Lo be connected in this case by means of parallel return feeders. Direct railway earthing cannot he used a.s a protective measme 011 DC systems, since this would involve stray currents. The measures to be adopted in this case arc dependent upon the op(~rating voltage. Necessary connections to the rails are made by mea.ns of voltage limiters, which establish a couclucting connection after a threshold voltage is exceeded, especially in the case of short-circuits. Connections between the tracks and components to be earthed on AC railway systems are to be carried out with galvanised steel cable, galvanised wire or flexible copper conductors. On DC railways, these connections must satis(y the current capacity requirements. They are therefore normally implemented as copper conductors. In especially important and critical situations, e.g. on railway platforms and loading roads, two earthing conductors are to be laid in parallel. Individual measures for earthing and traction current return routing are to be co-ordinated with the signal engineering designs. The appropriate measures are used to create an earthing diagram, which is contained in the layout diagram for the open track and is established as a separate document in stations.
6.9.11
Signals for electric traction
So far as signals for electric trachon are necessary according to clause 4.4, their locations are to be entered in the overhead layout plan with the graphical symbol shown in Table 6.15. The operator's regulations serve as a basis for this. Co-ordination with the operations department 1s necessary.
6.9.12
Establishing layout plans
The overhead contact hne system layout should contain all important information from the track layout within a distauc<~ of 15 m from the centre line of the outer track. The interaction betvveen the ovnhcad contact line system and other equipment can be recognised frorn the described sy!llhols (Figure 6.43). The acHu,.c;trnent: plan can he 11scd iu stations as a clear representation of th(' contact line system routing (Figure G 1-1). II has lwcn prepared to a scale of 1:;>00 lougit.11clinally to the track and l:GO trn.1ts\ <'ts<'.IY to the track. Iu stations, tlw n·n:uz/ dw.111n.111. shows tlw circt1it of th(' overhead co1tLarl li1t<' S_\stcm. 1t is t1scd for swild1:1.·11.,r; op1'.111.!um.s in tit<) overhead li1w uctwmk aud t<'{ll"('S<'llts the staudmd state of disrn1111<>tt(J1~; (Fii-',lll<' G.-t::i). _ T'hc e1i:rt/1:1.nr; duu;rn:111., 011h ,ippropriat.c for stations, contains th<' <'l<'s !.11<' id<)1ttification of Lit<' mu( i1tg, t.vp<' n11d <"01111<·<·( i()11 points of ( It<) <"outrnl cahl<' for t Ii<' r<'1110(,c control of ( lw m <'rlt<'ild !ill<' dis<
36-5
36-3
Track centre line
CJ7 CJ7
CJ7
Steady arm with standard lateral position of the contact wire
36-6 Steady arm with contact wire position deviating from the standard lateral position 36-2
36-4
Figure 6.44: Adjustment diagram (partical view).
6.10
Transverse profile diagram
6.10.1
Objective and information
The transverse profile diagram shows the arrangement and type of supports, the headspan equipment, the poles with the traction power supply lines and geometrical dimensions in a section through the railway permanent way. It assists the determination of necessary material, installation and maintenance.
6.10.2
Types of poles and their classification
The selection of the poles for the individual locations is also included in the planning of overhead contact lit1(\. Differentiation between several types of poles iu the overhead contact line system, such as sus71ens·io11, pole, midpoint anchor pole or knn:lnation pole, is made corresponding Lo their function in accordance with EN 50 I rn. The project engineer prepares an overvi('w of the pole types to be used, basc:d 011 t IH· d1antcteristic data of the type of m'<'rl1<\ad co11tact line to be planned and the sL1t ic analysis, from whid1 th('. pol<~ will I)(' S<-i<·
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6 Pla11ni!1g of overhead contact line systems ----------------
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Figure 6.46: Earthing diagram (partial view). 8
N
4
3
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4
8
6
5
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8
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3
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Figure 6.4 7: Pole types for DB's standard contact line type Re 330.
contact line. The numbers represent the following type of poles: 1 suspension pole with single cantilever; 3 and 4 suspension pole with twin cantilever in overlaps; 5 midpoint pole; 6 midpoint anchor pole; 8 termination pole. Poles can be mounted on top of the foundation (Figure 6.48 a), inserted into the foundation (Figure 6.48 b) or put over a tube (Figure 6.48c). The pole length depends upon the design of the connection between pole and foundation, which is to be determined during the planning work. The distance between the track centre line and the track-side a)
b)
TP
c)
TP
TP
Figure 6.48: Iuterface between pole and founclatiou, (a) bolt-mounted pole, (b) inserted pole and (c) p11ll-ove1 pole.
6.10. Transvmsc~ pm file dia&r,1H1
315
face or tlw pok is desiguated the dimension TP. The difference in height between top of rail and the top surface or the foundation is the dimension e and the pull-over or insertion length is th() E-dirnem;ion (cf. Figure G.48).
6.10.3
Pole geometry
The pole geometry shows the pole with cantilevers and lines in a profile transversely to the track and it assists the definition of the pole type. Figure 6.53 shows typical pole geometry for contact line type Re 330 with their identifiers.
6.10.4
Transverse switching lines, disconnectors on poles
Across track feeders connect disconnect.ors to the overhead contact line system. These feeders run directly to the contact line system overlaps, where the transverse switching is located directly adjacent to the overhead line to be connected (Figure G.49 a). Overhead lines on tracks that are not located directly at the pole carrying the disconnector are connected to the disconnector by means of across track feeders and drop feeds. (Figure 6.49 b). Across track feeders are often found in stations with flexible cross-span structures. The arrangement of the drop feeds must take into account the effect of wind and contact line movement. These feeders must be allowed for when selecting poles. Disconnectors with their feeders are fixed by the location of switchable overlaps. The positioning of the overhead contact line system disconnect.ors on the poles for the connection of circ'Uit groups in stations can be chosen within certain limits. Short cable routes between the disconnector and the control location, common use of cable troughs and glands are also taken into consideration.
6.10.5
Determination of pole lengths
The dimension TP is to be defined before the determination of the pole lengths, i. c. the pol(~ location in the transverse profile. Pull-on, inserted and mounted poles are to be classified in the transverse profile as shmvn in Figure 6.48. Finallv the vertical distance is determined between the top surfaces of the driven pile, tube or concrete foundation and the top surface of the lowest rail on the nearest track, the e-dimension. An earth covering 0,5 m thick is to be prmidecl for conCT(~te poles that are pulled over a tube welded to the driven pile. The drin'n t11lw must rise into the pok by at least 0,50 m. The foundation for holt,-rno11nted and insert('d poles 11111st project at !(~ast 0,2 m above the terrain level. The pole length follows fro111 thcs<' rnnditions. The ntilway profile existill,l!, ,1t the location, the ccn1tad, wire aid s,·st.('!lls ll('igh(,s, a pole extension Ce ahme the cantilever swivd hing<~ and any tu1.ction pm\<'! lines that lllllSt lw installed are also to lw taken into accot1nt. The pole length is illust rnt('d i11 Figm('. G.GO for connct.e pol(~S with driven pile fo11ndations and i11 Figm<' (i.;J l fo1 IJ0IL-11101111L<·d pol<'s ,, itl1 block f011ndatio11s, each in a I.rack ClltV<' 'T'h<' pol(' 1<'11µ.,t Ii for /! 1/,/1-()()('.'f' (()'/1('./!'/(' /!OIi's is 1 ii<' Sl!l11 or the
316
-----------
6 Planning of overhead contact line systems
Paralleling disconnector Supplementary feeder line
Across track line
1
2 Figure 6.49: (a) Schematic diagram of disconnector lines between disconnector and overhead contact line, (b) across track line between disconnector cross-arm and opposite pole.
pull-over dimension E, distance between the top surface of the foundation and the top surface of the rail e, contact wire height CVVH, supplement for superelevation 2/3 'U, system height and pole overlength U e. Example:
The pole length Mltotal of a concrete pole for DB contact linetype Re 330 is to be found. e = 1,15 has already been determined from the track profile. The track superelevation is 0,15 111. overlength U e 0,30 m system height SH 1,80 m contact wire height CWH 5,30 m supplement for superelevation 2/3 'll for n = 0,15 m 0,10 111 pole length NilTR above TR 7,50 m difference e between TR and top surface of pile 1,15 111 pull-over dimension E 0,50 m Lot.al pole length A1l1ot.al
9,15 rn
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Figure 6.50: Arrangement of concrete poles with driven pile foundation in embankment locations and curves.
FL
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Figure 6.51: Iustallatiou of an H-profile pol<' witl1 nH1<:r<'l<' foundation at an emhank1u<'111 local iot1
I
/ 318
G Pl~1.1n1ing of ove_rliead co__r~c1ct line systems
Top tube length 45 (0 26, 0 42) 45 (0 26, 0 42) 55 (0 55) 55 (0 55) Reference dimension - - - - - - H _ , . __ _ _ _ _ __::_.::_::_--=--::.._:__ _ _ _ _ _ _ _I ,_ _ _ _ _ __
--100
r\\'0
Registration arm length
"'s\'<}'l
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Figure 6.52: Dimensions for manufacture of a DB cantilever with pull-off contact wire support.
The pole length is to be increased to comply with a raster size of 0,25 rn, therefore to 9,25, to reduce the number of pole sizes. The e-dimension is to be corrected correspondingly and implemented at 1,25 m.
6.10.6
Cantilevers
A cantilever calculation program is used for determining the cantilever type with respect to tube lengths and configuration. A dimensional check is performed after erecting the pole. The cantilever calculation and manufacturing are executed taking into account any deviations that may arise during the construction phase. General contact line system data, specific weights, su 1>port data and route data are necessary for the determination of the cantilever type and calculation of the net element lengths. The general contact. line system data consist of the cl(~signation of the tensioning section, system, type of insulation, temperature range, cantilever type, tensile forces in catenary and contact ,vires, and other wire and cab!P types. Tlw following support data is also necessary: pole number, pole type, span leugth, contact wire height, contact wire and catenary wire stagger, distance between tn-1.ck side of pole and track centre line, pole inclination, track radius and line gradi()IIL The tc)stdts an) presented in a graphic or talrnlar form with the dirnc\nsions for (II(' 111;,u111f';,wt111e of the cantilever (Figure 6.52).
G.10 Transverse profile\ diag_r:am
319
Table 6.16: Concrete pole types of type He 330 for wind speeds of 33 m/s, radiu8 greater than 2000 n1. Pole pattern
Tube diamel.er of driven pile tube
RI R2
21 22 23 24
NB NB NB NB
R3 R2
Pole pattern 21 with - Overhead contact line - Return conductor - Parallel line feeder at pole head
Pole type I 2 2 2 2
Pole types 3, 4 Hild G NB NB NB NB
Pole pattern 22 with - Overhead contact line - Return conductor - Parallel line feeder on inner side of pole
Pole type
Pole type
5
4 4 4 4
NB NB NB NB
8
3 3 3 3
NB NB NB NB
Pole pattern 23 with - Overhead contact line - Return conductor - Parallel line feeder on inner side of pole - Feeder line
5
5 5 5
Pole pattern 24 with - Overhead contact line - Return conductor on inner side of pole - Feeder line
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6.10.7
Pole and foundation selection
The selection of the pole type its configuration and mechanical strength is carried out for each individual pole site. Selection tables provide assistance for typical applications or static calculations for individual pole locations (see clause 7.5). Table 6.16 shows the selection of pole types for Re 330. Th(' pole type designation NB 3 refers to the ;-1,pplication of a. concrete pole of type ;3 as shown in Figure 6.47 for new lines.
Exa1nple:
A concrete pole is to be found for the attachment of twiu cantilevers in an
ne
overlap usiug DB catenary system ;330 011 a curve with a track n-1,diufi R = 4000 1u without s11pcrclcvatiou. Tlw pole carries a.11 parallr a r:ulius I? 4000 111.
320- - - - a)
6 Plan11i11g_ofoverl1ead contact line systems
-~---------
b)
c)
r1 I I I I
d)
e)
/
Figure 6.54: Important types of foundations, (a) block foundation for bolt-mounted poles, (b) block foundation for inserted poles, (c) driven pile foundation. (cl) driven tube foundation, (e) direct embedding of a concrete pole.
The foundation type is determined from the soil properties, construction resources and the pole design. Steel and concrete bolted-base poles require concrete block or round foundations, or driven pile foundations with anchor bolts (Figure 6.54 a). Poles may also be attached to structures such as bridge decks. Concrete foundations with core holes accept inserted poles of steel or concrete, which are embedded in concrete or stone chippings after erection (Figure 6.54 b). Concrete poles can also be embedded directly in the ground (Figure 6.54 e). They can also be mounted on steel or concrete driven piles and cast in mortar (Figure 6.54 c). Steel or driven pile tubes can also be used to support concrete or steel poles (Figure 6.54 d). Foundations are selected according to the application. soil type, and bending load in accordance with tables or, in individual cases, with the aid of static calculations (see clause 7.5). Transverse profile diagrams combined with longitudinal profiles enable a clear representation the geometric dimensions and materials to be used (Figures 6.55 and 6.56).
6.10.8
Head-span structures
Head-span structures accommodate both the weight and registration of the contact line system. The earthed or energised upper cross-span wire is to be configured in accordance with the cross-span wire lateral forces. The upper cross-span wire is earthed in track radii greater than 800 m and energis0d in track radii smaller than 800 m. The type of catenary wire supports follows accordingly. The arrangement of the sectionalising determines the intermediate insulation in the lower and in the energised upper crossspan wire. Cross-span tensioning springs are used to compensate for the temperaturedependent conductor length variations and the associated conductor stresses. Track height differences up to 0,5 m can be accommodated by \cuying the system height. Lowered eross-span wires are required for larger track height differences (Figure 6.57). DB provides at least t,vo hearl-s1w:11. wires for safety n:;:tso11s. Four head-span wires are som<~times used, dqH'11di11g upu11 tl1<· numh<~r or supports and l<~11gth of the head-span
G.10 Transverse _profile _cl_i_ag='·_n_u_n_________
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t.O
o_
209) 2,438~ ~()\) 2,438 : ~
r
0 C\J
C\J
I
0,40
0
0
0
0
oi
oi
0
co
l
0
co
l{)
I
i,-j
I
3,10
•
3,10
I
•
~
I
•~;;-_rttt---::/7==il=-=-=~==::l==-=~·::::;.J::::====--it__:'._=-=--~=--=-;=t=_:::_=_:Jl·==;".::=~---H1~~P_t1
~,_-. .--------~ I 0
li)
/
R=3000
'
3,35
c5
R=2995,3
4,70
3,35
it--r----...1----'--
-
/II
0
li)
6 /II
of---
-C)
\ Function module
I
1
Number
) Pole
Unit
inclination mm/rn Function module
Number
Unit
Number of pole
No A161
Foundation
A1000-A11
1
Foundation
A1000 A11
1
Pole
8 2200- 821
1
Pole
B 2200 - 821
1
Catenary wire support
C 1100-C1
1
Catenary wire support
C 1100-C1
1
Contact wire support
C 1200 - C1
1
Contact wire support
C 1200- C2
1
Cantilever attacl,rnent
C 1300 - C301
1
Cantilever attachment
C 1300 C301
1
RC beam
G 2210-G2
1
RC beam
G2210-G2
1
RC support
G2110-G3
1
RC support
G 2110-G3
1
FL support
E?130-E1
1
FL support
E 2130- El
1
Railway earth
G 1000- GS
1
Railway earth
G 1000- GS
1
No. A161
Figure 6.55: Tta11sv<~rsc profile of a double track liue with individual poles.
322
6 Planning of overhead contact line systems
--------------------------
Pole No. 162
Line A-town to B-town
I
I Station 37 -fl 58 Sheet No. 87/11 J
Kmx.,
- X - - - X - - - X - - - X - - - i X - _ _ x.___ X - - - X - - X - - X - - X - -
_
XX--XX--XX--XX--XX--X)( I
.
r \_.;
I I I 11 I
r-XX--XX-- XX--XX--XX--XX-- XX--XX--
I/. v\
...
r
1\
'\
I
'·
\
\~.
"
\__,
\\
I
lO
co
lO
--
f'-.
~-
TR
v
1
~-
_,r-
-r--
·----
... --
5,00
- - X X - - X X - - RL
Function module
C'J
(0
---
- - x.___ X---- FL
co co
co
-
f'-.
co
(0
l!)
f'-.
0 Number
Unit
Anchor foundation
A 3000-A45
1
Anchor
D 1600- D3
1
Tensioning weights
D 1130- D5
1
Overhead line connection
D 1520- D4
1
Overhead line anchoring
D 1521 - D1
1
Tensioning mechanism
D1110-D12
1
Fastening components
D 1160- D104
1
Tensioning weight guide
D1140-D18
1
Figure 6.56: Longitudinal profile of contact. line tPnuina.tion.
1
'
6.10 Transverse profile diagram ________
323
=
+
- -~ I
(/)
u
E
0
lf)
ti)
I
s0
m
u
C
Cll
u5
0 Q
.9
(/)
>
1:
0)
u
m
u
E
lO_
E
lf)
.c
OJ
en>, f'.2--
TR
I
OJ
0 .0 Cll
'
0
C
Cll
u5
E
0 0
VI
I
s0
Figure 6.57: Accommodation of track height differences, (a) by means of different system heights and (b) by means of lowered cross-span wires.
structure. The head-span wire sag is dependent on the span width of the head-span structure and the relationship between sag and span width of the head-span structure, which should lie within the range 1/5 to 1/10. The poles are to be fitted into the track profile in the transverse profile diagram and the pole lengths determined. The polygon shows the lengths of wires for the headspan structure and permit prefabrication in the workshop. Disconnectors, across-track feeders and jumpers together with intermediate insulators in the head-span wires are contained in the profile diagram. Configuration programs provide a representation of the geometry of the head-span structure with material requirements (Figure 6.58). This type of representation simplifies the installation and provides material data for reconstruction of a head-span structure after damage.
6.10.9
Portals
The modular design of portal.s with standardised end and intenncdiatc frames as used by the Norwegian Long Distance Hailways (JBV), (Figure 6.59) pennits simplified configuration. These lattice frawc,vmk portals carry the supports in stations and on winding open tracks, to avoid push-off contact wire supports. A maximum of 9 tracks can he spa11nccL .Jl3V li,1s (~mplov<~d portal types 12 and],] since 1997. These have different. angle sections and can IH' selcd<'d as shown itt Tahl<' (i.17 Porbd LypC' 12 is <'lllplo_v<·d to span two
.. -- . -~---- _()_rlanning of overhead contact line systems
324
Length of head-span wire Bz65 19 96 m Length of lower cross-span wire Bz50 = 17 04 m Length of upper cross-span wire Bz50 = 17 04 m Maximum sag of head-span wire fq 2 29 m
167-27 HEB300 /12,25
167-28 HEB300 /11,75
~ ,_ _ _4_,5_0___+_ 3,06
4,99
RL
(J)
C\J
C')
5,03
FL
i_iil. C\J
5 87
11)
q
11) ~
0
ci O
II
0
0)
11)
lD lD
0
0)
II
20,16
-65
-65
Ill
-15
-15
o
I
-20 -20
ill
I I
II -40
IV
I
lD
-17011 -220 -170 -220
A
I I L ~:,~
0 C')_
_,_3_,1_9___,__4_,9_0_ _ _ _ 1,_71---+____ 4,_40 ____ --I~
--r+----+-i···~t~ Figure 6.58: Transverse profile in stations with flexible head-span structure and disconnectors, across-track feeders and jumpers at the Portuguese State Railway CP.
6 Intermediate frames
1-----
End frame
Q)
C
Bracket arm Solid wall pole
~
c
Q)
u
_,::
u
(1J
i'.::
:c
Ol
.c ii3
ii3
.c
>
0(1J
.c E Q) 17i (/)
~
3:
c0
0
Figure 6.59: Portal at Norw<~gi,1n Long Distance Hailways JBV.
Lattice steel pole
6.11 profiles - - Longitudinal -~--~ --------
------·----~-----·--·---------- --.-------
Table 6.17: Portal types at Norwegian .JBV.
325 -----------
Portal type Portal length in m Number of tracks
12 11
14 33
2
28
43
>2
tracks with cross-span widths up to 33 m, and portal 14 for more than two tracks with cross-span widths of 28 m to 43 m. The portal bridge length results from the spacing of the pole centres, which are determined from the track system and rounded up to the nearest whole metre. Bracket arms are mounted on the portal to support standard cantilevers. Track height difference are accommodated by varying the system height at the cantilever or changes in the height of the bracket arms on the portal. The radial loads in curves and the portal length determine the pole types to be used to support the portal. Where the radial loads are less than 6000 N and the portal lengths shorter than 30 m, a double-channel pole is used on one side of the portal and a lattice steel pole manufactured from angle sections on the other side. Lattice steel poles are used on both sides of the portal where the radial loads are greater than 6000 N and the portals longer than 30 m.
6.11
Longitudinal profiles
6.11.1
Contents
Longitudinal profiles indicate height contours in areas such as overlaps, contact line system height reductions and increases, above and below obstacles, traction power supply lines and dropper arrangement.
6.11.2
Dropper arrangement
Dropper lengths are calculated by computer software using the following parameters: contact wire stagger b at the support, longitudinal line gradient, track superelevation v,, track radius R, system height SH, tensile force in catenary wire and contact wire, employment of stitch wires and the specific loading per unit length. The dropper s7Jating i11 the spans is dependent on the overhead contact line system and the span lengths. The arrangement of the stitch ·win\ drop[J<\rs, can be obtained for contact line system Re 200 from Table G.18. Spacing of 9,S 111 between the droppers results for a 75 t11 span (Figure G.60). Tile drnpp<)t calrnlation during the design phase assists the assessment of rnaterial f!Tor:·11:1·en1.1·nts els in Lit<' ("clS<' of cantilevns. Th<' ex,Kt. dropp<)r lengths c·a11 IH' calculated
___ GP!anning of overhead contact line systems
326
Table 6.18: Arrange1rn~nt of stitch wires and droppers at the supports . , 200 . type Re Stitch Span wire length length
inm
Number of stitch wire droppers per support
mm
Distance Stitch wire Stitch wire dropper to dropper to support stitch wire dropper in m mm
Number of droppers in remaining span length
Support A l = l 2'. l 2'._ l 2'. l 2'.
80 79,8 71,6 65,1 42,5
18 18 14 12
4 4 2 2
2,5 2,5 2,5 2,5
3,5 3,5
1)
1)
1)
1)
14 18 14 12
2 4 2 2
2,5 2,5 2,5 2,5
2)
1)
1)
1)
2) 2)
6
6 6 4 5
Support B l = 80 l l l l
2'. 2'. 2'. 2'.
79,8 71,6 65,1 42,5
3,5 2) 2)
1)
6 6 6 4 5
1) No stitch wire 2) Only two stitch wire droppers arranged symmetrically to support point
and manufactured at the construction site after measuring the position of the contact line support fittings.
6.11.3
Contact wire height reductions
Longitudinal profile diagrams show contact wire height reductions in accordance with the calculation in clause 6.8.5. They illustrate the contact wire gradients and system heights to a distorted scale, longitudinal scale 1:2500 and vertically to the track 1:10 (Figure 6.61). The exaggerated scale highlights the effects of sag, system height and minimum clearances. The contact wire sag under ice load is depicted over four to five spans adjacent to a bridge structure, to verify that the minimum clearance criteria have been met between the top surface of the rails and the contact wire,
6.11.4
Traction power line longitudinal profile
Longitudinal profile for traction power lines contain the clearances to strnctures and other equipment. Similar by manner to the longitudiual profile representation, the line longitudinal profiles are drawn to different S('.ales, 11sually with the sea.le 1:500 along the track and I: 100 vntical to th<' track. Figmc G.G2 illustrates an <~xtract from a longitudinal profile.
6.11 Longitudinal_ profiles ___________ _
- - - - - 327
Pole B
Pole A
b= +0,4
b= -0,4
(push-off)
(pull-off)
/y =14 m
Catenary wire Bz II 50
Hr =10kN Dropper
Bill
10
E cq
lo
0 0 0
Stitch wire Bzll 258 c5 Hy =1,7 kN
----- ... 2.5
LO
0
0
c5
c5
LO
0
C')
C')
0.
0
0
c5
c5
0
0 0
0. 0
§j §j
Stitch wire Bzll 25 H =2 3 kN Contact wire Cu AC-1UO ' 0
0
j
Hew= 10 kN
...
Droooer dimension Dimension I I inm Dimension1 II) in m Dimension I ll inm
95
""' """'
iHy1 1 006 0.936 1.028
95
9.5
""' iH1
1.305 1.035 1.127
...
95
...
95
... 9.5 ...... 9.5 -135,2 _ ..
.
75m iH2 1.051 0.781
0.873
iH3 0.907 0.637 0.729
iH4 0.873 0.603 0.695
iH5 0.949 0.679
iH6 1.136 0.866
0.771
0.958
IHy1 iHy2 0.991 0.884 0921 0.814 1.013 0.906
Figure 6.60: Dropper spacing and lengths in span type Re 200 for droppers not capable of carrying currents.
6.11.5
Minimum clearances to overhead lines and traction feeder lines
The required minimum clearances bet-ween live parts of the overhead contact line s,vstem, such as contact lines, supports, clisconnectors, third party objects and to the standard gauge are dependent upon the operating voltage. The existing clearances have to be detennined taking acoouut of temperature, ice loads and wind. If traction power lines are attached to the contact line structures, then they are a part of the contact line system. The minimum clearances according to EN 50 119 or to the operators stipulations like German railway directive 997, valid for DB since 1997 and an~ applicable, as summarised in Table G.19. !\li11inrnm clearances in open terrain according to EN 50 341-1 and EN f>O 341-3--l: apply to traction power lines that are not att.ac-hC'd to contact line pole, but t.o d<~dicatcd poles. rfah!e (i 2()
Sllllllll
_ __ ________ ___ 6 Planning of overhead contact line systems
328
-------------------
---11,0
m
(])
6,30
UI
=i
t,
6,20
m 6,30
6,10
6,20
2
if)
6,10 6,00 5,90
(0
C'l_ 0 lD 'St_
C\J_ 0 lD
II
II
II
5,80 -
~ u ::r:
5,70
C/)
~-,~
_:~_
LC)
I
~~
C')
0
lD
lD
II~ II
~
~ ::r: u
5,90
II
~ 0 V5
Cf)
6,00
lD lD_ lD
lD 'St_
5,80
I u
5,70
co
5,60
II c5
II c5 II
::t:
:s: ::r:
5,40
lD
-st.o
II
0 C\J_
co
::t:
5,50
II
'J
C\J.co
5,60
Ol ~- 0 lD C\J_
\ I
II
~ ::r: u C/)
6,10
5,50
II
Ci ~
0 (/)
5,40
5,30
5,30
5,20
'
5, 10
- _,
5,20 \
I
'
-
/
5,10
5,00
5,00
4,90
4,90
4,80
l l~j 6
co
6
co 60,0
4,80 0
6
6
co
co
65,0
65,0
C\J
~
6
6
co co 55,0 45,0
C')
6
co 55,0
'St
lD
~
~
6
6
co
65,0
~
'
OJ
70,0
Pole number
OJ
70,0
Span length
I
Figure 6.61: Extract from a contact wire height reduction for DB type Re 200.
6.11.6
Traction power lines
6.11.6.1
Introduction
Traction power lines such as feeder lines, auxiliary feeder lines, bypass lines and return current conductors are all part of the electric traction system. They are mostly installed on the contact line poles. Required minimum clearances to earthed equipment is in accordance with the line voltage and the climatic conditions. 6.11.6.2
Line attachment to poles
Traction power lines, are a.ttached to linepost or suspension insulators at the top of contact line system poles. If several conductors of traction power lines are attached to the same contact line support, crossarms are fixed to the pole shaft. Crossarms ensure that the minimum clearance is maintained between the line and the pole or other objects. Section supports from rigid points in the line and are equipped with dead-end insulator sets. Dead-end supports are found at the beginning or end of a line section. Table 6.19 shows minimum cbu-ance to objects within the raihvay property and Table 6.20 clearance applicable w!.en traction povver lines are routed across terrain not owned by the railway opera.tor.
6.11_ Longitudina( profiles
""-~---
-------~-~~-
329
22.0 1'e0
C\J
l!)
0
(\J C\J.
II 0
0)
l!)
(\J
II 0
0)
id id
-
20.00
E
V
ru II
C\J
II 0
1xAl625!.
0)
C\J_
II
id
C\J
l!)
0
0)
E
"-
(")
-al en
Ql 0)
D
Ql
0)
C
C
Ql
·s
~ 'g
0
I
0)
i'il E id "-
a)
0)
20.00
E
V
19.16
co
0 0
C\i
II
II
0
0)
a
~ E
i'il
E
15.97 Line (\J
co
(')
12.15
10.50 .__________
4.0
Pole
Pole
5 40
26 25
--
--7.35
28.85
...
2950
26 90 30 90
197-8an
197-10n
197-1 0an 85 80
197-12 19 90
I
f maxao Maximum line sag at conductor temperature 80°C
Figure 6.62: Extract from a power line longitudinal profile.
6.11.6.3
Clearance verification
The routing of a traction power line and its arrangement at the supports determines the geometry of line and supports. Temperature variations, wind actions and ice loads cause conductor positions which may not violate the minimum clearances between the conductors tlwmselves and between conductors and other objects. Acceptable clearances must be verified in case of specified most-unfavourable conductor temperatures and loading. As an exampl<\ a maximum conductor temperature of 80°C is assumed at DB for feeder, auxiliary feeder and bypass lines. ·wind action wit.It th<' specifi<~d pressure causes swinging of t./l(' conductors nwasured by th<) anµ,le ·P front t.h<' Yntical axis. Then the coefficient k Celli he dd.ennin<~d from EN GO :341-:3--1 [G.12] T,1hl<' :i. l :3/UE.2 \\'liic:!t is
6 Planning of overhead contact line systems
330
Table 6.19: Minimum clearances from various objects to energised components of the contact line system to German railway directive 997 [6.11], voltage AC 15 kV. Object Direction Clearance Basis Kr. from Object in m 1
2
Standing surface for electrically skilled staff, electrotechnically instructed persons and railway system instructed persons Standing surface for general public
downwards sideways upwards
all
1,50 1,50 3,50 l) 2,75 2 ) 5,00 2,25 3,50 4,50 0,18 0,60 0,15 3 ) 0,22 4 ) 1,50 5 )
all all
1,00 0,60
downwards sideways upwards upwards all
10
Platform Obstacles with plate-webbed mesh (mesh width < 30 mm) Structures such as platform roofs, superstructures, tunnels, buildings, Signal or lighting poles, working platform parts of signals, which are negotiable, Barriers open Structures that are not ascend, such as signal vane, obstacle on ascents Windows in buildings for electrically skilled staff, electrotechnically instructed persons and railway system instructed persons Windows in building for general public
11
Road surfaces on crossings
upwards
12 13 14
Catenary system another circuit group Feeder line Return current cable
15
Across-track feeder Contact line system - Across-track feeders in same circuit group
all downwards upwards sideways all all
3 4 5 6
7 8 9
16
all
sideways
sideways
2,25 3,57
5)
EN 50122-1
997.0101 pp 10
997.0101 pp 13 997.0101 pp 11 Ebs 02.05.19 Sh.2 997.0101 pp 13 997.0101 pp 13
997.0101 pp 14 997.0101 pp 14 997.0101 pp 14
7)
2,75 5 ) 4,07 7 ) 5,50 1,50 2,00 0,50 1,25 2,00 0,10
997.0101 pp 14 valid from 01.01.97 997.0101 App. 2 pp 207 997.0101 pp 10 997.0221 pp 5
1) outside DB property, 2) DB property, 3) for Re 75 to Re 200, 4) for Re 250 to Re 330 , 5) may be reduced to 0,6 m under certain circumstances, 6) up to component, 7) up to track centre
used to calculate the required minimum clearance at midspan. Only the sags according to 40°C conductor temperature need to be considered in case of wind action. Verifi,cation of clearances between adjacent conductors as well as to the ground and any objects under and close to the line is required with sags and conductor position occuring under th<~se temper;-ttmes and c:ouclnctor loadings. The clearances between the r<:turn cmT011t conductor and the termiuatcd contact line equipment are verified as ,rn <'x,u11pl
6.11 LongitudiILc1l profiles------~
331 . -----·------ -------------·-------------=---
Table 6.20: Minimum clearances to traction power lines and their fittings for AC 15 kV and AC 25 kV. Object
Direction
Clearance inm
Loading platforms Ground surface ILegotiable Climbable trees Buildings with: Roof pitch > 15° Roof pitch :S 15° Air-inf-lated hall, thatcliecl roofs Antennas, lightning protection
vertically vertically vertically all
12,0 5,5 2,5
No 1 2 3 5
Standard EN EN EN EN
50122-1 50122-1 50122-1 50341-1
3,0 5,0 10,0 2,0
Table 6.21: Recommended electrical clearances in mm according to EN 50119. Supply voltage DC DC DC AC AC
0,75 kV 1,5 kV 3,0 kV 15 kV 25 kV
Static condition
Dynamic condition
100 100 150 150 270
50 50 50 100 150
closest proximity, both in still air and in the swing condition. The German railway directive 997 [6.11] require minimum clearnnces of 500 mm in vertical direction and 1250 mm in horizontal direction between attachments of return current conductors and live µarts of feeder lines. Furthermore, a clearance of at least 300 mm has to be obeyed during short-term approaches of the return current conductor to live components. An appropriate selection of the conductor type and its tensile stress can ensure the compliance with this requirement. 1~1ble 6.21, corresponding to EN 50 119, Table 5.9, specifies the cleara,nccs under static and dynamic conditions depending on the supply voltage. For AC 15 kV a value of 100 mm applies. A minimum clearance of 3,0 m to buildings and of 2,5 m to trees or bushes under any condition shall be maintained according to EN f>0 122-L For return current conductors the same requirements apply as between the standing surface and conductors for live conductors according to EN 50 122-1. Under the conditions applicable to DD's overhead contact line 11ctwork a c:011cluctor temperature of 60°C is assu1t1<:xl in still air for conductors 240-ALl sagecl with 20 N /mm 2 tensile stress a11d a temperature 40°C i11 swu11g rn11ditio11 with a swing angle of G5°. The return cun<~11t eonductor nta\ sag below the conta<·t wire h<'ight at the vertex of the sagging curve. Tlte spc~cific clearance between ac(iY<' compo1ie11ts of overhead c·o11Lact lines hav<~ ( o lw
6 Planning of overhead contact line systems
332
------------------~-----------"---
Detail
i---
1 I
-~!------: 6--: -"'
I
Pole A
I I I I
I XI
m
Pole B
:
I I
I
a
Return conductor line centre line
Detail 1--
Return conductor line
:
I
<(
A _,
~
I I I I I I
m
Co/Jt. Set Ii
~
/Je -Q
Track centre line
I I I I
:
-----
l
:
Return conductor line :
a:
+-+--T----I-,:j f)C/i
-"'
Ore(j
I
'
-----
oleA
:
I I I I I
y
----
DA
--
--
I I I I
Co/Jt. : Set;,, i
I
'f)e1 I
I I
I I
a
Figure 6.63: Top view onto terminating contact line and the deflected return current conductor. Where: T PA distance between track side face of pole A and the track centre line in m, T Ps as above for pole B, DA pole diameter A at the height of the return current conductor suspension, Ds as above for pole B, b contact wire lateral displacement of the terminating contact line system in m, kR distance of return current conductor centre line to attachment of the contact line system at pole A in m, kR = DA/2 + T, T cross arm length in m, l span length between pole A and B in m, a distance from the centre line of pole A to the verification point in m, whereby a measures to the end of the live side of the insulator.
The verification of minimum clearances is carried out with the following steps: Determine the point a of the smallest clearance between the return current conductor and the terminated contact line, Determine the position of the verification point, i.e. at position a, Determine the position of the return current conductor centre line at position a, Calculation of the return current conductor sag .fac at point a, Calculation of the spatial clearance RRc-cA between the swung return current conductor and point a. Figure 6.63 shows the arrangement of the return current conductor and the terminated contact line in the plan view. Figure 6.64 shows section AA. The sag of the return current conductor .faL at point a, viewed from support A, for return current is obtained according to (5.34) and (5.36),
.foe= (G'/2H) · a(l - a) -with .facmaxAO
= (G' /SH) · (2
4focma:dO ·
a(l - a)/2
4 · .facmax40 · (1 - a/l) · (a/l)
G.11 Longitudinal pt~~fi~_:c; ____________________________________ _
RC
333
y
z
,
C/\
cw
YRC-CA
TR
Figure 6.64: Section AA of the deflected contact line with return current conductor at point a. Where (all dimensions in m): RCA deflected return conductor, RC centre line of return conductor, RCR position of rest of the return conductor, CA catenary wire, CW contact wire, RRc-cA spatial clearance between the return conductor line and catenary wire, ZRC-CA vertical distance between the return conductor line and catenary wire, ZRC-RA vertical distance between the return conductor line centre line and the deflected return conductor line, YRC-CA horizontal distance between the return conductor line and catenary wire, YRC-RA horizontal distance between the return conductor line centre line and the deflected return conductor line, ZRC-TR vertical distance between the return conductor line centre line and TR, (TR = top surface of rail) !Re sag of return conductor line at fJ = 40°C at point a, 1PR deflection angle of the return conductor line in degrees.
Distances
znc-RA
and
YR.C-RA
4 · .f'Rcrnax,10 YRC-ltA
= 4 · fncrnax40
follcnY at point a (Figure G.64)
· (1 ·
-
(1
a/ l) (a/ l) cos
(6.7)
a/!) (a/l) sin
(6.8)
The sag of the return cunent conductor .foe at point a is calrnlatcd for differing support point height,s from (5.37) •
.foe -
I
G ·a
I - u. H 2
+ h · a/l
-
.
-1.fiicmaxlO ·
("
1
.6.hnc is the height difference between the suspension points of the rct,un1 current conductor at pole A and pole I3 It follows for ZJlc nA and t/nc--H_.\
6 Planning of overhead contact line systems
334 Pole A
X
Return conductor line centre line
Pole B
Catenary wire
tf
CA a
Contact wire
z a
ZcAA-TR
Z CAB-TR ZRCB-TR
TR
Figure 6.65: Side view of the terminating contact line system with return contact line. YRC-RA
=
4 · ]RCmax40 · (1 - a/l
+ 6hRc/(4fRCmax40)) · (a/l) sin
The spatial position of the catenary wire at the verification point a and with reference to pole A, it follows according to Figure 6.65 from YRC-CA
=
ZRC-CA
=
kR
+ (DA/2 + TPA - b) · a/l
(6.9)
and ZRCA-TR - ZcAA-TR - (zcAB-TR - ZcAA-TR) . a/l
+ 4fcAmax40. (1 + LlzcA/(4 · fcAmax40) - a/l)ajl, D A/2 + T. T = 0 and kR = D A/2 for the attachment
whereby kR current conductor directly to the pole. The spatial distance RRC-CA
=
j Y~C-CA + z~C-CA
>
of the return at point a is
(6.11)
he
It must be greater than the minimum clearance RRC-CA
RRc-cA
(6.10)
s:
s
Example: The clearance between the return current system is to be found at point a. 1. Initial data: Type of return current conductor Tensile force of return current conductor sH Span length l between pole A and B Position of verification point a Suspension points of return current conductor Maximum sag fRcmaxrlO Traverse length T of return current conductor Maximum sag fcA,na,dO of the cal.euary wire for type Re'. 200 seen from the higher support point Pol<~ type rnncret<'. pole NB 1
conductor and the anchored catenary
240-E-Al-DIN 48 201 20 N/mm 2 65 m 25 m from pole A equal height 1,87 m 0,55 m 0,739 m
G.12 Project . clocurnentatior1____________
335
The geometrical layouts correspond to Figures 6.62 to 6.65 with zcAA-TR = 6,70 m, ZCAB-TR = 7,30 m, ZRCA-TR ZncB-TR 7,10 m, DA/2 = 0,15 m, TPA = TPn = 3,60 m. 2. Calculation of the distances YRC-CA and zn.c-CA /RC = 4 · 1,87 · 25 ( 1 65 kn
0,15
YRC-CA ZRC-CA
+ 0,55 = 0,70
25) 65 = 1,770 rn
= 0,70 + (0,15 + 3,60 = 7,10
111
0,40) · (25/65)
= 1,988
m
6,70 - (7,30 - 6,70)25/65
+ 4 · 0,739 · 25( 1 + 0,60/ (4 · 0,739)
(25/65)) / 65
= 1,099 m . 3 calculation of the minimum clearance between catenary wire and return current conductor RRc-CA = Vl,988 2
+ 1,099 2 -
1,770 = 0,502 m
.
With the minimum clearance S = 0,30 m to be observed, it follows that S < Rnc-cANo violation of the minimum clearances occurs if the construction tolerances are observed. If the minimum clearance is violated, it is possible to increase the installation height of the return current conductor or to employ a longer outrigger. The return current conductor is normally installed at the height of the catenary wire. The return current conductor is attached to a traverse or a pole when terminating catenary systems are routed to the anchor or with a centre-point anchor cable. In this context, clearance verifications for feeder and auxiliary feeder lines are to be performed for other objects. Clearance RRc-cA is to be rechecked if the local geometry is altered.
6.12
Project docu1nentation
The pro_ject documentation ind udcs all information necessary for approval, material procurement, implcme11tatio11 of coustrnction and inspection. These are in detail List of contents, List of changes,
Approval8 for constructi.on. E:r:planatory 1·eports ,vith i11strnctions for erection, Overhead line diagrams, adj11st.mlc length diagrams for disconncc-tor r<\111ote <·ontrnl, Trn,11,.,vcrse pro.file d·ia1;ru:m.'i, :-rnd1 as track tra.11svcrsc prnfile diagrams, polygons for noss-spa.11 sl rncl,mes. Longitudinal profiles, such il~ ( 011b1<·L lin<' h<~ight reductions, line height diagrams, Project, rdat<~d st rnd1m•s wii 11 drnwi11gs and cak11latio11s, if 11cccssar.,·, and the /\!/o,/1:-rials l1.sf i11cl11di11g t ii<· poll~ and fotl!ldation I.able.
336
6 Planning of overhead contact line systems
The objective of the explanatory report is to establish the planning fundamentals and assumptions made for the project, in order to inform the examiner and subsequent construction manager of the configuration constraints. Information losses can thus be avoided during handover of the project for construction. The explanatory report contains the technical requirements, planning documents, technical explanations for the equipment and approvals for project implementation. The technical requirements for the configuration of the overhead contact line system can be found in Section 6.2.2. If the configuration is based on a standard design, then the technical requirements are defined in advance and it is sufficient to state the type of overhead contact line system. The planning documents corresponding to clause 6.2.3, upon which the configuration is based, are to be cited. Reports, such as inspection reports and other meeting reports, which contain information relevant to the system layout, should also be listed. The technical explanations relating to project equipment are subdivided into poles, cross-span elements, overhead contact line system, traction power supply line, return current system, railway earthing and protective measures and profile clearance. Special structures with calculation notes and drawings, as necessary. The description of the subsoil based on an existing subsoil investigation and the type of foundations should be included in the technical explanations to the construction project part. Any special foundations are to be listed in the construction project part. The overhead line diagrams follow the explanatory report. Earthing diagrams, adjustment diagrams and transverse and longitudinal profiles are to be attached to the project as needed. The material list, which includes the pole and foundation table at DB, forms the basis for the erection of the overhead contact line installation and subsequently for the spare parts inventory. It is expedient to use data bases to administer all project data, which can also assist the operator to perform maintenance and to achieve more rapid fault repairs.
6.13
Computer supported configuration
6.13.1
Objectives
Computer supported con.figuration methods are being increasingly used. These either
use programs to support individual configuration phases or for an integrnted process with a computer. There are advantages in using interactive modules. The structure and method of operation of interactive configuration with computers is explained using the example of the SICAT MASTER® [6.13] program system developed by Siemens. Configuration work based on the SICAT MASTER® process allows all work processes to be executed interactively with the computer. The main points are the Processing of the win:11,.r1 and related calculations, Preparation of diagrarn,.s, Selection of materials and Redundancy-fr0.e ir11plen1,enlatum and administration of changes.
I I
6.13_Computer supp01tcd configuration
337
---------------- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SICAT MASTER
I
Project administration
I
Track geometry
Wiring
Layout diagram
Transverse profile
Selection of components
( ___ Po-le_l_is-ts_~J
Contact line Contact line equipment and feeder line longitudinal profile
equipment
Cantilever lists
I
Project administration
Figure 6.66: Modular SICAT MASTER®.
structure
of
The processing of systems for both stations and open track with different technical requirements and parameters is possible.
6.13.2
Structure and modules
The SICAT MASTER® program consists of various modules (Figure 6.66) that are linked to each other systematically. Important modules are Acquisition, administration and provision of global data, Recording of the track layout, Contact line system circuit diagram, Wiring (Figure G.67), Contact linf' c!quipm<~nt height reduction (Figure 6.G8), lVIaterial t,·pes and quantities and El<~meut selection and out.put lists.
6.13.3
Data managen1ent
Confad l'l:11,1· sysl!'l/1. d1:sz_11n rlo,/,u ;utd vrojffl-syH:cifir: ylol)(Jl rlalll are held in the SICAT lVIASTEn01J prngr;u11 Th(' rntdig11rntiot1 co1111tw11c-(!s \\ it.l1 1lH' ddinitiou of the design-
6 Planning of overhead contact line systems
338
stcr
l,rallk
SIOLA II • Bes annun l:lllfc
•
/ Anzahl kopiertcr Bespanmmgsobickte :
~
I
r.---
Aru:ahl benotigter GleiqJfade :
, Spiege I
t
" +-
.
.t
r ;r
Spiegeln qucr zum Gleis
j
i
j
---···
:. r- Spiegcln lang• zum Gleis B-Mo8 spiegeln
I--···--
loi:!
II
Abbruch
!!
GP-lisle
+
Figure 6.67: Entry of contact line system elements m the distorted scale representation. ~I
t ,&.
+-+
+ f{r
....
"2l
13 '
(xO.yO)• (0.00. 0 00) · (d,cdy)•
(3943 92. i 580 03). obs• ·1240 64____
Figure 6.68: Interactive window for
cont.a.ct.
line syst
•
G.13 _Co111p11Lcr supported configuration
Overhead contact line point
Overhead contact line termination
339
Electrical overhead contact line element
Wiring point
Section insulator
Overhead contact line connector
Figure 6.69: Hierarchical structure of the overhead contact line elements.
specific global data. Project-specific system data is generated during the course of the configuration work. The system administers both data categories in separate databases. A new project database is created for each new project.
6.13.4
Hardware and software
The system runs on a PC platform. A standard high-performance computer for graphical applications is sufficient. CAD programs such as AutoCAD are recommended for graphic processing and for plotter outputs. The object-oriented programming language C++ showed itself beneficial for the development of the system. The contact line system is displayed as a complete system within the computer in an object-class hierarchy (Figure 6.69). The function group structure described in clause 4.7 forms the basis. An import/ export filter for DXF files provides the graphic system interface. This graphic format is widely used and can be imported and exported to almost all CAD systems.
6.13.5
Application
The strnctme of the program systern corresponds to the project phases shown in Figures G.l and G.2. The processing of individual consecutive modules compels the project engineer to use standard processes, which ensure uniform quality of the design. The flexibility and ease of use of the system results in considerable time and cost benefits, especially clming alterations to the project specifications, such as track layout and signal locations. All configuration clocurncnts and a rompletc database of the systems, which can be used for maintenance, arC' availahk at rnmpktion of the configuration work.
6 Planning of overhead contact line systems
340
6.14
References
6.1 Grunder, H.; Waeckerlig, W.: Informationen ,mm Gebrauch von photogrammetrischen Aufnahmen / Erfassungen im Eisenbahnbetrieb (Information for the use of photogrammetric survey / survey during railway operation). In: Brochure Grunder Engineers / Furrer and Frey, 1994. 6.2 Grunder, H.; Kocher, M.; Waeckerlig, W.: Rechnergestiitzte Fahrleitungsprojektierung beim Umbau des Bahnhofs Spiez (Computer based planning of overhead contact lines for conversion of Spiez railway station). In: Elektrische Bahnen 91(1993)4, pp. 125 to 130. 6.3 Geissler,G.: Einfiihrung in die Vermessung mit GPS-Systemen (Introduction into the survey using GPS). Information brochure of Engineering company for geodatic systems, Munich 1994. 6.4 Sueberkrueb, M.: Technik der Bahnstromleitungen (Technology of overhead contact lines). Verlag von Wilhelm Ernst & Sohn, Berlin, Munich, Dusseldorf, 1971. 6.5 German Railway: Ebs Regelwerk (Standard design book for overhead contact lines). 6.6 Krumpolt, J.: Optimierung von Oberleitungen elektrischer Bahnen (Optimizing of overhead contact lines for electrical railways). TU Dresden, Institut Elektrische Bahnen, diploma thesis 1996. 6.7 Berg, G.; Renker, H.: Weichen (Points for railways). VEB Verlag fuer Verkehrswesen, Berlin, 1976. 6.8 Deutsche Reichsbahn, Reichsbahnzentralamt Muenchen: Vortrage bei den Unterrichtskursen mit Erfahrungsaustausch iiber Konstruktion, Bau und Betrieb von Fahrleitungsanlagen (German State Railway, Central Administration Munich: Lessons on experience exchange concering desgin, construction and operation of overhead contact lines). Conference May, Munich, 1942.
6.9 Kief31ing, F.: Projektstudie zur Entwicklung einer Oberleitung fiir hohe Geschwindigkeiten (Studies for development of an contact line for high speeds). Siemens AG VT 3 Overhead power lines, 1992. 6.10 EN 50 122-1: Railway applications - Fixed installations. Part 1: Protective provisious relating to electrical safety and earthing. December 1997. 6.11 DB: German railway directive Gbr 997 - Oberleitungsanlagen (Overhead contact lines). 6.12 EN 50 341-3-4: Overhead electrical lines exceeding AC 45 kV. Part 3-4: National Normative Aspects for Germany (NNA). 2001. 6.13 Burkert, W.; Puschmann, IL System zur interaktiven Projektierung von Oberleitungsanlagen (System for interactive planning of overhead contact lines). In: Elektrische Bahnen 93(1995)3, pp. 104 to 109.
7 Cross-span structures, poles and foundations 7 .1
Loading assumption
7 .1.1
Introduction
Contact lines are subject to different loadings. Dead loads from conductors, fittings, insulators and supports act permanently and can be determined accurately from technical data and dimensions. The conductor tensile forces also act. However, they depend on the conductor temperature in case of non-automatically tensioned installations. Where not installed in tunnels or other protected areas, contact lines are exposed to the weather and occasionally experience heavy additional loadings from wind action on conductors and structural components as well as from ice accretion on conductors. These loadings can be determined by statistically evaluating records of long-term weather observations. \,Vind and ice are randomly distributed variables; their frequency of occurrence can be described by probabilistic laws [7. I]. During erection and maintenance, contact lines can be subjected to additional loadings that must be withstood by the structures to ensure personnel safety. Specification of design loads includes an additional factor for construction and maintenance loading.
7.1.2
Permanent loads
The dead loads of structures, fittings and conductors act vertically and the loads resulting from coriductor tensile forces act horizontally in case of level attachment points. Dead loads are independent of the conductor temperature and result from the dimensions of the installation. During the life cycle of an installation they vary only because of the contact wire wear. The conductor tensile forces are more or less constant in the case of automatically tensioned contact and catenary ,vires. In the case of fixed terminated wires and conductors, they depend on the conductor temperature, which varies as a function of the ambient temperature, current loading and ice loads, if any. Structural design must consider the maximum tensile forces generated. The vertical loads result from (see clause 5.1.3.2)
Vi= G'(/1 + li+1)/2 + H[(NNi - NNi 1)/li + (NN1 - NN1+1)/li+iJ
(7.1)
where Ii and /;+ 1 arc the span lengths adjacent to the support, NNi is the height of the supports all(! H the horizontal conductor tensile force. 'flw lwrizontal condw:tor tensile force results from conductor tensile stress and cross s<'.ct.ion Th<)V also dctc•rn1iw'. the horizontal loads at tlw supports according to the gc)Oilldri< <()llditious Tlic detenniuation of thcs<' cornpon<'ll!.s is d<)1-dt with in clause
7 Cross-span.structures, poles and foundations
342
.5.1.3.2. For a support with adjacent span lengths li and li+J ,vith the track radius R it follows (7.2)
The ,·alues bi stand for the horizontal stagger at the supports.
7.1.3
Variable loads
7.1.3.1
General
Variable loads due to climatic conditions are added to the permanent loads. All contact lines are exposed to wind in the open. In many regions. including Central and Northern Europe, in Russia, Northern China, Japan and North America, ice accretion on conductors occurs in addition to wind action. Extreme climatic conditions result in maximum loadings of contact lines.
7.1.3.2
Wind loads
Wind loads are determined from wind velocities which vary in time and location. In particular, wind velocity increases with the height above ground according to: V11
= V10
·
(h/10)°'
(7.3)
where h is the height above ground, a the roughness parameter and 1,· 10 the reference wind velocity 10 m above ground. Meteorological wind velocities may be evaluated according to standard [7.1] which applies to transmission lines and distinguishes between four terrain categories: Category A: extended water surfaces in wind direction. flat coastal areas and deserts. Category B: open terrain with very few obstacles, e.g. farmland with few trees and buildings. Category C: terrain with numerous small obstacles like hedges, trees and buildmgs. Category D: suburban areas with more or less densely arranged buildings and/ or many trees. For these terrain categories; the exponent a may be taken as 0.12; 0,lG: 0,22 and 0,28 respectively [7.1]. Equation (7.3) applies to the mean values of wind velocities averaged over 10 min or 1 h periods. Refer to [7.2] for deterrnining design wind velocities by region. In practice, design of contact line installations refers to standards for transmission lines and civil engineering. Figure 7.1 depicts the wind regions and reforenc-e wind velocities for Germany according to [7.3]. Germany is dividr.d into four ,,·incl regions. The wind velocities are related to a 10-min averaging period and a GO year return period. From these basic assumptions, the design wind velocilu:s vn. are dc)rivrd. vVhen designing, difforentia.tion is mad<\ lwtween loadings which u1w-;t 11ot. lim<) au:,· effect on train
Figure 7.1: Wind map for Germany acc. to ENV 1991-2-4. Reference wind velocities Region 1 24 m/s Region 2 28 m/s Region 3 32 m/s Region 4 33 m/s
operation and loadings under extreme conditions where no damage to the supports may occur. This applies especially to areas where extremely high winds occur, for example due to hurricanes. As an example, DB AG (German Railways) designed the contact lines for their classical network such that an unrestricted operation is guaranteed up to 26 m/s. In coastal areas, where high wind velocities have to be expected, 29 m/s is used. For high-speed lines, routed partly on high viaducts, a value of 37 m/s is used. From the design wind velocity VR the aerodynamic wind pressure is given by .
qo
= r /2 · VR2
(7.4) 3
where I is the air density being 1,25 kgm- in most cases. The wind pressure determines the wind loads on the structural components such as conductors, cantilevers and poles. The wind load on a contact line span with length l on each of the adjacent supports is Fw
=
(Jo ·
1
cw · l/2 · d · sin \JI
(7.5)
where cw is the drag co(dficieni being 1,0 to 1,2 for conductors (see Table S.7), cl is the conductor diameter and / the span length. The angle \JI is relative to the line, for \]I = 90° the wind clin)ction is perpendicular to the line. The wind load, according to (7.fl) acts squarely 011 the conductors. To detennine the total wind action 011 a support, the ,vind loads from the adjan·11t spans an~ summed geometrically. 'The wiild load 011 supports, esp<'ciallv 011 tlw poles, acts in th<' din!<·t.iou or tlw wind nt th<' C('tlt n· of grmit.,· of I It<· pol<' and is giveu by: F\\
I' == 1/o. (·p ..·\
(7.G)
7 Cross-span structures, poles and foundations
344
Table 7.1: Wind velocities in m/s for design of DB AG's contact line installations compared to values of design standards. Operation DB Southern and Central Germany North-German plains Coastal area Elevations above 100 m
26
EN 50 341-3-4 poles conduct.ors 26 30
ENV 1991-2-4 24
2!)
28
-
-
32
43
37
29
34
32 37
where A is the total projected area of poles or pole sections. The drag coefficient cw depends on the pole design. In the case of lattice steel poles it varies over a wide range depending on the solidity ratio, i.e. the portion of area filled with steel sections to the total area (see [7.2]). For practical applications of contact line design the values provided in Table 5. 7 may be adopted. :rviany standards contain information on wind velocities and corresponding wind forces. The European standard ENV 1991-2-4 for wind action and EN 50 341-1 combined with EN 50 341-3-4 are considered relevant in this case. It should be mentioned that according to EN 50 341-3-4 the wind pressures on poles and conductors differ by the factor 0,75. This is due to the reduced wind reaction of conductors to gusts. Only gusts with a duration of more than 30 sec cause an equivalent force on supports compared with poles where gusts of a few seconds cause full reaction. Therefore, Table 7.1 also lists data used for verification of operational reliability in Germany. In the European standards for overhead contact lines, specific wind loadings are specified. 7.1.3.3
Ice loads
Ice loads with different characteristics occur on conductors and poles. With a few very exposed installations excluded, only the ice accretion on conductors may lead to operationally restraining conditions and additional loads, especially those ice accretions from precipitation characterized by high density and strong adhesion. Rain freezes on conductors at temperatures around 0°C and, depending on the duration of the adverse weather condition, cylindrically shaped ice is formed. The ice is clear or opaque, has an approximc1,tely circular cross section and adheres to the conductor with high density. Such an ice accretion can prohibit the pantograph from contacting the contact wire. In the case of automatically tensioned installations, the sags increase considerably and impair operation. As with wind loads, ice loads also follow statistical rules that are disn~ssed in detail in [7.2]. In establishing design, ice load references are often made to th<' requirements for overhead transmission lines. Following the German standard [7.4] the design ice load would be
C'.cc
= (5 + O,ld)
iu N/1n
(7.7)
7_._2 Transverse support equipment and
rs>!~£____ ..
345
where d is the conductor diameter in millimetres. For Germany. the n\turn period of this ice load can be assessed within a few years [7.5]. DB AG designs their contact lines using half of the value resulting from (7.7) because of the current heating of conductors and the ice cleaning effect of pantograph operation under the contact wire. Nevertheless, ice accretion has occurred widely throughout DB AG's nct\rnrk for extended periods and caused significant impairment of operation. In the case of autornatically tensioned contact lines, this is due to a considerable increase in sags and not to mechanical overloads.
7.1.3.4
Simultaneous action of wind and ice
Simultaneous action of wind on ice-covered conductors increases the mechanical loading on conductors and supports and should be considered when ice formation is reinforced by wind action, see [7.2]. In the case of contact lines, the action of wind and ice is taken into account when necessary, by combining ice load with a wind load reduced to half of the loading without ice (see clause 7.8.2.3).
7.1.4
Loadings due to erection and maintenance
During erection and maintenance of a contact line, additional loadings occur due to linesmen, to temporary anchoring and fastening of tools and because of conductor stringing operations. These additional loadings must also be considered when designing an installation. Poles, cantilevers and cross-arms should be checked for a vertical load of 1,5 kN, caused by the linesmen, acting at the most unfavourable position.
7.2
'Iransverse support equipment and poles
7.2.1
Transverse support equipment
7.2.1.1
Types of support equipment
Grouped under this heading are cantilevers of varying designs including cantilevers across several tracks, fie:r:ible cross-spans and rigid portals. Section 4.2 illustrates contemporary designs of these components and describes their functions within the overhead contact line. In general, they are used to support th(' contact line equiprnent, to fix the lateral position of contact and catenary wire aud to transfer the loads acting on the overhead contact line equipment to the poles reliably. 7.2.1.2
Swivel cantilevers
The most frequently used design for individual s11pports in au overhead contact line installation arc swivel 1·m1,tilevers made of t11hular S(~ctions. Tlwv are fixed to poles, buildings or other strnct11n\s and pivot on a vertical axis. Cantilcv<'rs rigidlv fixed Lo pol<'s an~ 110 longer used for llC\\' installations. Howe\<'!. tliev can still be found in st'n ic<'. Figtm' + 28 dt\picts a cantilever design using a 111/1·1wn; w?:r1: sw'i'uel clarnp
346- - - -
------------
_______________________ 7 Cross-span structures, poles and foundations
Figure 7.2: Cantilever for two trolley bus contact lines
which is fixed to the cantilever tube. In addition to supporting the catenary wires, this provides the connection with the top tube or top anchor rope. With this design, mainly tensile forces occur in the top tube, to a large extent permitting the use of ropes instead of tubes. Mainly axial forces form the loadings of the structural cantilever elements in this type of design. The cantilever shown in Figure 4.31 uses a catenary wire clamp which is moveable along the top tube. Consequently, bending moments occur in the top anchoring element requiring an adequate rating. Mechanically effective cantilever elements may consist of steel tubes, steel or copper alloy wires, aluminium tubes and bars or tubes made of glass fibre reinforced plastics, which also serve as insulators. The design and geometry, as well as the magnitude and direction of acting forces form the basis for determination and analysis of the cross sections of the elements, together with the materials used. 7.2.1.3
Cantilever across several tracks
If supports can only be installed on one side of a multi-track line, cantilevers across several tracks are a viable alternative. Several designs of multi-trnck cantilevers are used in service. The design shown in Figure 4.33 uses a cantilever arm made of two U-channels connected face to face or a square tube. As shown in the Figure, the cantilever arm is fixed to the pole by a hinge and carries drop verticals with swivel cantilevers attached. The vertical loads are supported by rope-type gu~·s arranged obliquely between the cantilever arm and pole. Cantilevers across several tracks constructed of plastic (GRP) tubular sections arranged in parallel, are often adopted for mass transit installations. These cantilevers are used to support the bridles of trolley contact lines (without a continuous catenary wire) or trolley bus contact l7:ne8. (Figure 7.2). Rope-type guys, arranged obliquely, are also us<'d in these cases to carry the vertical loads. In contrast to main line railways the plastic c:mnponcnts are utilised to provide insulation making separate insulators superfluous. Frequently, these installations are supplied by DC 600 V or DC 750 V. Cantilevers across several tracks must carry the H'l Lind cuid horizontal loading oft he contact lm,e equipment. Their length should b(~ lilllit.ed to ,tpproximately 10 m because of erection and maintern-u1u~ difficulties.
347
Figure 7.3: Lattice-type crossbeam made of aluminium (Photo: Mtiller-Gerlach).
7.2.1.4
Flexible transverse support equipment
Flexible support equipment for contact lines can have benefits in areas such as stations having more than two parallel tracks because space to install poles between tracks is not needed. The individual supports can be arranged within the cross-span as desired. This is advantageous especially for the wiring of station ends with many points. These types of flexible cross-spans have reached lengths up to 80 m. In practice, they should be limited to 40 m because of operational and maintenance issues. Figure 4.34 shows the principles of arrangement. The vertical loads, resulting from the loads of the individual contact lines, are carried by head span ,vires and the horizontal registration is held by cross-span wires. The upper cross-span wire carries the horizontal loads resulting from registration of the catenary wires and the lower those from the contact wires. The head span and cross-span wires connect the contact lines mechanically. Any movements are transferred between the lines. This is considered undesirable with high-speed traffic. Consequently, DB's Gbr 997.0101 [7.6] guidelines recommend separate poles for each track of DB's high-speed lines. These guidelines have generally been adopted system wide. The head span wires have a sag between one eighth and one tenth of the cross-span length. Design of head span equipment involves calculation of the head span wire loads and selection of dimensions. However, rating of c:ross-span wires is simple because their sag can be neglected.
7.2.1.5
Portal structures
In the case of portal strnctv:res, a rigid beam carries the individual contact liues. The beam is supported by poles 011 both sides of the line. Some designs use dniJ! vcrhcals with swivel cantilevers fixed to the crossbeam, ,vhile with othern the nossli<'atll carries tlw vertical loads and is used onlv for the lateral guidance of the ratemn\· ,vires. A lower cross-span wire is us<\d to rq!,istn the contact wires. Figme 4.39 shows a beam designed as a lattice ginlcr Portal structmes are used for lengths up Lo 40 in. For long portals, lattice steel design pnw<'s t.o h<' advantageous. For spans up Lo 2:J ttl I-I-beams 01 hollow st<)C! sections rnav lw lls<'d To reduce maiut<~n,wc<\ al111t1iuitr1u portals hav<'
7 Cross-span_ structures, poles and foundations
2
4
4
2
6
5
7
8
4
3
3
4
8
Figure 7.4: Tensioning section of an overhead contact line
been used for some mass transit installations (Figure 7.3). Crossbeams are loaded by vertical forces and by moments from drop verticals for cantilevers in their vertical plane. Additional bending in the horizontal plane occurs if mid points or tensioning equipment are arranged at a crossbeam.
7.3 7.3.1
Poles Types of poles
Poles used as supports of a contact line must perform various functions. Figure 7.4 depicts a tensioning section of a contact line outside stations (open-route). The contact line equipment starts at a tensioning pole (Type 4 or 8). This pole has to carry the loading from the cantilever and also the forces exerted by tensioning of contact and catenary wires. In some cases, anchors are arranged to counterac:t the tensioning force acting in line direction (Type 8) thus reducing the loading on the pole and its foundation. The intermediate poles (Type 3 and 4) within the overlap section have to carry two cantilevers arranged on brackets. They are loaded by bending moments and by torsional moments due to different radial forr.es of the individual contact lines. These poles require torsional stiffness. The suspension poles (Type 1) are equipped with just one cantilever and have to withstand loads created by contact wire and catenary wire stagger, radial forces in curves and wind loads. The mid pmnt pole (Type 5 ) is arranged approximately in the middle of the tensioning section. It is loaded by the contact line and the mid point anchors. There are section poles for termination of mid point anchors (Type 6 and 7) adjacent to the mid point pole, that are loaded by forces in line direction and frequently anchored. The poles in the next overlap are similar to those previously described. The poles for head-spans carry loads from the head span wires, cross-span wires as well as those from tensioning equiprnent a.ctiug in line direction if any. The height of these poles must take into account the sag of the head span wire. The poles carrying crossbeams are loa,ded by vertical and transverse loads only since the crossbeams are fixed to the pol<'.s by hinge joints, to avoid moment joints. Loads from cross-span wires, cantilevers and terminated contact lines have to be added to the loads from crossbearn,.'L Poles in contact line installations, in addition to being used for cantilevers, are also used for rad'ial r:onl,act l-ine ·registrat·ion and terminations without cantilevers. These poles have to lw ra.ted a('cording to the applied loads. Trnct'ion power l1,rw8 cue often installed on the overlwa.cl line pole::; resnlting, in different condnctor configurations and additional loads. The traction power lines are usually
Table 7.2: Loading condition for contact line poles. Variable loads
Designation of pole 1 l
Type of pole
Permanent loads
1
Suspension pole with one cantilever
dead loads of conductors, cantilevers and poles forces due to radial action and stagger
--
3, 4
Suspension pole with twin cantilever
as 1 torsional moment due to radial forces and stagger
- as 1 torsional moment due to wind action
wind loads
5
Mid point pole
as 1 - loadings due to anchoring of catenary
as 1
6, 7
Mid point pole
as 1 loadings due to anchoring of catenary
- as 1
2, 8
Tension pole
- as 1 - loadings due to anchoring of catenary
as 1
1) see Figure 7.4
supported with suspension or tension insulators. Figure 6.53 depicts some pole configurations as adopted for DB AG's high-speed lines in Germany. The power lines may be parallel feeder lines having the same potential as the contact line. Therefore, they only require a reduced clearance to the contact line. Supply feeders or by-pass feeders can be switched separately from the contact line. In accordance with German standards, they require a clearance of at least 2,0 m from the contact line. Pole types may be divided between suspensfon poles equipped with suspension fosulator sets, intermediate tension poles and dead end poles equipped with tension insulator sets. The dimensions of the pole top must be determined in correlation with the traction power line arrangement This ensures compliance with minimurn clearances as specified by relevant standards such as EN 50 341-1. In Germany, required clearances are 0,20 m for 15 kV and 0 ,35 m for 25 kV. The sag of traction power lines must also be considered at mid span.
7.3.2
Loading assu1nptions
Various types of external loads act simultaueously on the supports of ovedicad contact lines. Depending 011 thtional ]o,1ds 'Iii<' lo,\ds on pol<•c, n·s1ilti11g from
350
_··-·- -~------ __ __ J
Cross~spanstructures, poles and foundations
the contact lines are considered as normal loads. Table 7.2 shows commonly adopted load combinations. E.ueptional loads can also occur if traction power lines are installed on the poles. They account for less probable loading conditions, e.g. unbalanced ice accrebon on individual spans or loads resulting from component failure. When rating poles, the load combination resulting in the maximum stress has to be selected. Loads from tensioning of contact lines are high and act permanently. To accommodate this characteristic they are factored by increased partial .factors. The loads due to traction power lines have to be determined according to the application of the pole, e.g. following the assumptions in EN 50 341-L The wind velocities are specified in Table 7.1 and must be stipulated for each installation separately. For head span poles, crossbeam arrangements, midpoint anchor poles and tensioning poles, the loads have to be combined following prescribed principles. To cover all relevant combinations in practice is beyond the scope of this book. Poles must be rated for the given loading cases and the forces resulting from the loads occurring for a particular application. The design methods and varying design factors affect the results.
7.3.3
Structural design and materials
A large selection of pole types are utilized for contact line supports. Lattice steel poles acc. to Figure 7.5 are constructed with four leg members made from angle sections and cross bracing. Their strength can easily be adapted to the required loading condition. DB AG uses a pole family starting with dimensions 800 x 600 mm at the bottom and angle sections L 80 x 8 up to dimensions 1600 x 2000 mm and angle sections L 150 x 14. They are adopted for tension poles on line sections outside stations and support head-spans. Double channel poles (Figure 7.6) consist of two U-channels which are connected by flat steel strips at spacings of 500 mm. They are tapered in the vertical direction. Channels [100, [120, [140 and [160 are used frequently. The double channel poles are characterized by differing bending moment capacity on either axis. Therefore, they are used primarily for support sites without tensioning equipment along line sections outside stations. Many overhead line installations use steel poles nwde of H-beams, which are readily available ex-stock. Their disadvantage is their relatively high weight compared with their strength. In addition, the cleffoction, ,vhich often governs the rating, is higher for this type of pole compared to double channel poles and requires heavier beams than would be necessary in view of the loading itself Ivioreover, they offer a low torsional strength, which limits their use for poles ·with twin cantilevers. Tapered thin walled steel poles form an int(~resting alternative since their dimensions can be adjusted to the loading requirements. Frequently, these poles are used for mass transit installations in urban areas. They are proclucecl by rolling, drawing or welding enabling the manufactme of poles with specific cross-sectional dimensions, strength and torsional rigidity. S'vu:n r:011,r:ref;e ywles are also used for contact line installations (Figure 7.7) [7 7]. They are d1aractcriz<'d by ('.irc1tlar crrn-;s sccLio11s. ;1, hollow con\ and produced with a conical
-------------------- _ _ _ _3=-.,5:__;:cl
-- --
350
0
0 0
0)
--
600
F'igure 7.5: Lattice steel pole for overhead contact lines.
F'igure 7.6: Double channel pole.
increase of the diameter from the top to the bottom by at least 15 mrn/m. They are spun in two-part, horizontal casings that are rotated on their longitudinal axis. The spinning process achieves a high concrete strength of 70 N/mm 2 according to C70/80 and recently up to 100 N/mm 2 according to C95/105. The high density of the concrete protects the reinforcement against corrosion and prevents cracking. Concrete pole reinforcement can be fabricated adopting conventional reinforcement bars or pre-stressed, using high tensile steel wires. The pre-stressed poles have become more popular for railway applications. Pre-stressing of the steel wires is carried out before spinning. After the concrete sets, the pre-stressing strands are cut at the mould ends which then induces a compressive force in the concrete pole. During bending this pre-stressing must be exceeded before the concrete sees tensile stresses and subsequent cracking. Figure 7.8 shows the structure of a spun concrete pole. Over the past years different kinds of defects have been reported in spun concrete poles [7.8, 7.9, 7.10]. These defects included cracks along the separating joints of the nwttlcls, longitudinal cracks of differing lm1gth and width, transverse cracks and torsional cracks. Results of various investigations into the dd<'c-ts suggest that the faults were due to flaws in structural design including inadcqnate conncte thiclrness and reinforcement. cover, insufficient helical rciufon-cment and rnishandling during rnanufad.tue. i\Ioclifications to t.lic st;-rndan!s and qualitv ,tss111;u1c(' 11icasures Lak<'ll IJ:,' 111,uutfadurers irtdicat<\s Umt simi!m defects will not. n'-O
I
I'
352
7 Cross-span structures, poles and foundations
-···---···-··-·---··-------------'~-----'-'------------=-
Longitudinal reinforcement Helical reinforcement
Figure 7. 7: Spun concrete pole of an overhead contact line.
Figure 7.8: Structure of a spun concrete pole.
may be considered as long-lasting -~·omponents. Some railway oµerators, e.g. the OBB use concrete poles with a solid core, produced on vibration tables. The reinforcement is arranged into rectangular casings. Concrete is poured in and compacted by means of external vibrators. As a consequence of the lower concrete strength and the solid cross section, these types of poles are considerably heavier than spun concrete poles. When produced to best practice, concrete poles achieve maintenance free long life. For overhead contact line installations, they have proven benefits especially in connection with direct-planted foundations [7.11). However, for tensioning poles relatively massive cross sections are required. If stays cannot be used, they may look clumsT
7.4 7.4.1
Rating of cross-span supports Introduction
Cross-span suppcwts, such as cantilevers, flexible head-spans and portals are stressed by the loadings caused by the contact lines and other auxiliary lines being supported by the structure. Thr. task of rating a. polC:! includes determining the internal forces and moments and to rate the cornponents taking into account the relevant standards. The following section will deal with the most frequently used designs of canti.levers and _fl,exible head-span,,,. Other designs may lie rated by adopting the forces detailed here and using standard ci vii t•ugi1w<'ri11g static methods.
7.4 Ratiugof cross-spau supports __
-----------'V1< 3 FcA,W FcA,H .----v---v------l----------o,,' -
4
~'----------
Fcw,w ~
-
fcwH
Figure 7.9: Loading of a cantilever.
5
7.4.2
Cantilevers
7.4.2.1
Loading and internal forces and moments
The load carrying elements of a tube-type swivel cantzleuer are the top anchor, the cantilever tube, the registration arm and the diagonal strut. if any (Figure 4.28), supporting the cantilever tube towards the top tube and reducing the def-iection. On the cantilevers and thereby on poles, various load combinations act depending on the pole position, whether outside or inside the curYe. the type of support: pull-off or push-off, the wind action and the ice e.ffect, if any. The individual components of the load result from the vertical load due to the contact line according to equation (5.6a), the vertical load due to the ice-covered contact line. the radial load of the catenary wire according to equation (:3.10), the radial load of the contact wire according to equation (5.10). the wind loads on the catenary and contact wire according to equation (5.7), the dead load of the tube-type swivel cantilever, which is assumed to act approximately at half of the cantilever length. Figure 7.9 shows the forces acting on a cantilever. The ,,·incl action has to be assurn.ecl as acting iil both dirPctions alternatively. To sim-plify the analysis. the individual inputs are summed to vertical and horizontal components.
i
i
!!
(7.8) Fci\ Few
= Fc:J\,11 ± Fc;\,W Fcw.11
(7.9)
and
± Fc:w,w
(7.10)
The force F 10 P adi11g 011 the top anchor 1s, if the rn111ur negfocted
F;op - (Vi::w · /,\ - Few · h1d / h\ The forces iu the uuitile, <'r tube an' in sectiou 3
effe( r of t lw
force Fe.\ is
(7.11) ,j
(7.12)
I I,
7 Cross-span structures, poles and foundations
354
~-7'
~
6
7
Fcw
Vcw
Vcw
Figure 7.10: Loading of a registration arm.
and in section 4-5 (7.13) Without a diagonal strut, a bending moment occurs at point 4, where the registration arm is fixed (7.14) The diagonal strut modifies the system to one that is statically indeterminate. However, since the diagonal strut is, applied as closely as possible to point 4 (Figure 7.9) it may be reasonable to assume that the strut carries all the forces acting perpendicularly to the cantilever tube and transfers them to the top tube. Then, the force acting in the strut F 0 can be obtained from: (7.15) The bending moment acting in the top tube at point 2 is determined by (7.16) Figure 7 .10 shows the strain in the registration arm ca used by the load from the contact wire. Thus, \/cw is the weight force of the contact wire span supported by the steady arm with the dead weight of the steady arm, the fittings and the registration arm included. In the case of a push-off cantilever, the force For in the dropper is (7.17) and in the case of a pull-off support (7.18)
If Fcvv · hs 2 1 c::w · l,1_ 7 a compression force wou Id occur in the dropper leading to an uplift. which should be avoided when designing a cantilever. \Vhere necessary, a strut has to be provided instead of a slack dropper. The bending moment at the attachment of the dropper is (7.19)
7A_ Hating of cross-span supports 7.4.2.2
Rating based on Eurocodes
For ratings based on Eurocode (ENV 1993-1-1) [7.12] the design values of the actions have to be determined at first according to ni
n2
Lrc,/i1<,j +,q,1Q1,,1
Sc1 -
j=1
+
(7.20)
Lrq,i\Jio,iQK,i i=2
There, the following partial factors apply for permanent actions Go 111 ,: ,c 1,35 when the action is unfavourable, 1,00 when the action is favourable, for variable actions Qom,: rQ 1,50 and the combination factors for wind: \Ji 0 0,60 for snow/ice: \Ji 0 = 0,70. Note that the summation in (7.20) may not be understood arithmetically. Rather, the total of actions in the considered cross section or component have to be determined considering location and direction of action. The design values may be moments as well. The proof may be carried out using interaction relation in case of components loaded in tension or compression.
,c -
(7.21) In (7.21) Nsc1, .IVly,Sd and .Mz,Sd represent the actions in tension and bending acc. to (7.20) and Npl,Rd and Mpl,y,Rd, respectively, the plastic strength according to Np1,Rc1
(7.22)
A · or/'YMo
and (7.23) Here, ar is the yield strength of the material, A the cross section, ll'p 1 the plastic sectwn modulus and S the static modulus. In case of tubes S
= (2/ 3) (R3
r3)
( 7. 24)
where R is the external diameter and r the internal diameter. In r-ase of compression and bending, the proof is carried out according to Nsc1 Xrnin ·A· af/,M1
+
ky · A1y,Sd H:pl,y ·
ar/,M1
+
k'I, · ]\fz,Scl H-'pl,z ·
< l O
ai/,~dl - '
~I> (~I ')-)
Here, Xrnin is determined from (7.26) and ky;;, from
(7.27)
356 - - - - - - -----------
------ --~-
7 Cr·?ss-span structures, poles and foundations
---
Table 7.3: Charad,<\ristics of aluminium and steel tubes used for overhead contact lines Material Diameter, A I z Wp1 H1e1 tl1ickness mm-
10'1 mm'1
HY1 mm:l
rnm
3,5 3,5 4 4 5
247,40 313,37 477,52 640,88 1020,50
1,603 3,230 8,715 20,960 54,210
1,233 2,019 4,150 7,624 15,490
8,13 10,15 13,51 18,08 23,05
1,786 3,433 5,798 10,425 21,167
3,5 4 6 6 6
247,40 477,52 923,63 1206,37 1394,87
1,603 8,715 28,136 62,309 96,106
1,233 4,150 10,231 17,803 24,027
8,13 13,51 17,45 22,73 26,25
1,786 5,798 14,778 24,648 32,928
•)
Illlll
Steel
Aluminium
26 32 42 55 70
X
26 42 55 70 80
X
X X X X
X X X X
10:i
mm 2
If (7.27) yielded a higher value, kmax = 1,50 would apply. The undimensional slenderness >." applying to tubes is
"5 = and
>-/(rr · JE/ar)
(7.28)
follows from
¢=0,o(l+a(~
0,2)+"5 2 )
(7.29)
The imperfection coefficient a may be taken as 0,21 in case of tubes. The value µ, in (7.27) is obtained from !L
since
= "5(2 /3p
/3p !l
=
4)
+ (vVp 1/Mlc 1
1) :S 0,9
1,3 applies for tubes in cantilevers there is
L 4~ +
(TVp1/M1e1
-
1)
(7.30)
The data for TVp 1 and Hie! may be obtained from Table 7.4.2.2. The example shown in clause 7.8 demonstrates different procedures of verification. To guarantee serviceability for use, the deflection of components in cantilevers is limited to 1/100 of the member length. This limitation can be decisive in cases of cantilevers without diagonal struts. In case of a proof based on the pt order theory, the component of the force in the rcgistr;,,tion arm perpendicular to the cantilever tube ;,,ccording to (7.15) causes the deflection. Using nomenclature according to Figure 7.9 and the condition that /5 _ 1 is less than l,i--i the ·ma:nrn'u:m deff,ection follows from [7.13] to (7.31)
In the case of c,rntiln(?rs \\·itl1 a rnrnplica.ted, statically indeterminate design, it is recommended that cldorn1;-II io11 IH) calculatPd h\' means of a comnwrcially available computer program for t rnss st rncl.11r<'s that ca11 nm 011 a standard PC.
7.4_Hatiug_,c:ifcross-spau supports
357
V By
~L~
A Fsx =Hru,. h QA
~
wire
Headspan
V1
h UR
OB
,
Y2
Y1
h OR
B -h-- F Bx =Ha,
-
Vu
V;,
l-=!-X_1_ _,_
X2
x,
-~
Urmer cros span wire Lower eras span wire
-- -----
- FO
FO -
a
-
Figure 7 .11: Forces and sags within a head-span
7.4.3
Flexible cross-supporting structures
7.4.3.1
Introduction
Flexible cross-supporting .strnctures, called head-spans, carry the vertical loads, due to weight forces of contact lines and their supports, through the tensile force in the head span wires. The head span ,vires are bend at the points of attachment of contact lines. The task of head span rating is to design the head span wires and to determine the loads acting on the poles.
7.4.3.2
Loading, internal forces and sag of head span wires
The forces clue to the contact line are obtained from the adjacC'nt longitudinal spans by averaging the span lengths li on both sides of the head-span (7.32) The dead weight is equivalent to a vertical load of 220 to 250 N for each support. VimLi
Go111,;
+ 2:';0
(N).
'CJ111.1
GoHL1
(7.33)
In addition to thc' support loads, the dead load of head-span and cross-span wires, of section insulators and an (\red.ion load of conventionally 1000 \T lu--'l\ e to lw considered. These loads should be distributed to the individual 8Hpp01ts to sirnplif\· tlw analysis. Head-spa.n wire8 are 8trnng with a oag Ymax equal to 1/8 to J/l() or the lwad-sp,lll length a (Figure 7.11). Note that. t.he dfect. of t<'tt1pen1tun~-dep<'lld<'nt \i-lriation of length on tlw sa9 of hc(l,d-s7;m1. w1:n:s n1av lw 1wglect<'.cl. The calculat:io11 of forces and the oag of lwad-spau wires rna\ lw dc'l<'rn1itl('d graphically or by 11wa11s of' cqttivalcul 1110111ent.s. Th(' grn.pltind 1net,hod t
7 Cross-span structures, poles and foundations
358
The following Figure 7.11, represents a head-span supporting three contact lines along the tracks. The analytical calculation of head-span wires is explained below. The horizontal components of the conductor tensile force at points A and B are known as top reaction forces. Both horizontal components have the same value: (7.34) Since the sag Ymax is given, the horizontal component of forces in the head-span wire is obtained from the maximum equivalent moment Mrnax being Rax
=
(7.3.5)
A1rnax/Yrnax
The vertical components at the poles are obtained from n
VAy
+ Vsy = LVi
(7.36)
i=l
where n is the number of contact line supports. Starting with the balance of moments at A n
Vsy ·a=
L Vi ·Xi+ Rax · 6.h i=:l
the vertical component of support forces at pole B is obtained by (7.37) From (7.36) and (7.37) the vertical forces at A can be derived
vc\y
=
t= Vi - (t v;.
Xi+ Rax.
6.h)
Ia
(7.38)
i== 1
1 1
Following Figure 7. 11 the equilibrium at the support k yields to k-l
1:\y · Xk 1
= Rax · Yk + L (xk
.1:i) · ½
(7.39)
i== 1
At the position of the maximum sag the value Yk is equal to Yrnax· Then from (7.39) the horizontal component of the head-span wire force can be obtained
Rax
= ( 1/\ y
/;,-]
· Tk
L Vi(:rk -
xi)
)
/
Ymax
t=l
T'he vctlue
.IJmax
follovvs hrnn the sag a11d frorn the selected l<\ngths of pol<'S.
(7.40)
7.4 Hatingof cross-span supports
359
v~
,B
A:
-Y:a~
:I~
-
I I
~
I I
I I I I
SH
I
--'-
I
I
LSWH
I I
I I
---
hrn
I
hA
I I
SSH --
I I
I
I I
CWH
I I
I
I
I
I I
---
I I I
I I
-
-----
-
-
---
I 7-
- -
I
em
I I
eA
hB
e~-+
TR
FO
I
8 011
8 m2
-I
-
a
7.4.3.3
Figure 7.12: Determination of pole lengths within a head-span
Height of installation, determination of pole lengths
The contact wire height CWH above top of rail is the reference for determining pole lengths. The lower cross-span wire height (LSWH) is = 0,40 to 0,50 m above the contact wire. The system height SH of the contact line being between 1,40 m and 2,00 m is another parameter to be considered. The structural support height SSH of the support in the head-span has to be added. It depends on the design of the upper cross-span wire as live or earthed and varies between 0,80 m and 1,20 m. With the dimensions shown in Figure 7.12 the required height of the line connecting the points of fixing the cross-span wires at both poles measured at the point of the maximum cross-span wire moment is
hm
= C\i\TH +SH+ SSH+ LSWH +em+ (0,1 ... 0,15) a
(7.41)
The sag of the head-span wire forrning the last term in (7.41) is chosen between 10 and 15 % of the span. The dimension em results from the difference in height of the top of both foundations and the top of rail of the reference rail being (7.42)
The relation between the heights of head-span wire fixing and the value hm according to (7.41) is then (Figure 7.12) (7.43) From a stock list of available pole kngt.lis h\ and hll are selected and the sag Ymax has to he deten11i11cd finally frorn equation (7..-ll):
//max= h 111
(C\VI-I +SH+ LSvVH +SSH+ ('rn)
l
I
'
II
l
(7.44)
k!~
This rn.luc is 11s<'d to ndc1tlate Lli<' ltori1(:11tnl r<'a
,,
it
"i/
~
:1
r'i
11
:J
________________________ 7 Crnss-span structures, poles and foundations
360
7.4.3.4
Loadings and internal forces of cross-span wires
The cross-span wires are loaded by the pre-stressing force Fps, the radial forces of the contact line and the wind loading. The radial forces act in determined directions set by the support positions, while the wind loadings change their direction. The forces Fucs in the upper cross-span wire follow from n
n
k=l
k=l
n
n
k=l
k=l
L FcA,Hk ± L FbA,Wk · lk
Fucs = Fpsu
(7.45)
and
L FcA,Hk L FbA,Wk - lk
(7.46)
The forces FcA,Hk and FcA,Wk result from (5.10) and (5.17) respectively for the catenary wires. For force Fies in the lower cross-span wires it applies analogously Fies = Fps!
+
n
n
k=l
k=l
n
n
L Fcw,Hk ± L Fbw,w1c · l1c
(7.47)
and Fies= Fps!
LFcw,m k=l
L Fbw,w1c · lk
(7.48)
k=l
The forces Fcw,Hk and FcW,Wk result from (5.10) and (5.17), respectively. The crossspan wire springs are installed at the pole that experiences the lower load resulting from the radial forces. When determining the cross-span wire forces from the loadings of the individual contact lines, due consideration must be given to a situation where the radial forces and wind forces balance each other. E. g., the wind loads need not be considered for pole B if the radial forces that act on pole A are greater than the wind forces. 7.4.3.5
Rating of head-span wires, cross-span wires and supports
The head-span wires and cross-span wires haw to be rated assuming maximum forces detc~rmined using the equation (7.49) where ~/Q and ,Mi are partial factors, n is the number of parallel wires and A their cross section In most cases, at least two, for long-spans sometimes four Bronze wires with 50, 70 or !:Fi mm 2 cross section according to DIN ,18 201, part 2, are adopted. In case of the rating ;-tpplic-able for DB AG's installations rQ is 2,7, i\Il is 1,1 and 2 a 560 N/mm . For
7 .4 H atiug,of cross-span ~1:!_l_)J)_()_rt_s- -
,,
_____________________ - - - - - -361 -
_ _ _ _ _ _ _ _____;;;a'-----------_ _ _a_o_1_ _ ------------a_1_2 ______ .,.._ _ _a_·2_:i___ , 1
h
A[A ~
~-l /\-f
'!-~/
Ho,
; Fcw,_,1-1.,._1_a+1--"+------,H-12___ H_12_ _F._cw_,1-1_~-+:
V1
.
V2
---
--
--
---
c
1
--- TR
Figure 7.13: Cross-span arrangement of a trolley contact line.
The poles are loaded by the head-spans with the forces Hax, F~cs and Fies· Frequently, loadings from traction feeder lines, from termination of contact lines and from cantilevers fixed directly to the poles have to be added. The rating of the poles will be treated in clause 7.5. The approach given there can also be adopted for rating crossspan poles. The foundations can be designed by the methods described in clause 7.7. For the rating of head-spans, computer programs or table formats are used which systematically utilize the principles of rating as described above.
7.4.4
Horizontal registration arrangements
Horizontal registration arrangements and cross-spans can be encountered in the central urban areas of mass transit installations. They permit the support of trolley wire systems from walls of buildings or poles relatively far from the tracks. They also accommodate the arrangement of contact lines of crossing and branching tracks at large squares. The poles can be erected at locations far from the tracks where they do not interfere with the road traffic. Figure 7.13 shows a cross-span for a twin-track line. The loads 1/1 and Vi in accordance with (5.7) follow from the contact wires as well as the radial forces Fcvv,H 1 and Fcw,I-h in accordance with (E>.27). Since the radial forces act in the direction of pole A the tensioned wire O 1 has to be selected to carry the load Vi. The gradient of the wire can be chosen between 1: 10 and l: 15. The following applies
Viao1 / hi\
(7.50)
The transverse wire i11 !wt.ween the supports then must carry the load
H,:2 - Fcw.11 1
+ Ho,
cos
u,
~ Fcw,H 1
+ ,,·, ao1 / hi\.
(7.51)
The tensiollc-d wirC' supporting support 2 must carry the resultant fore<~ from H 12, l"c:w, 112 alld 1 2 «.nd hils to be ananged in the direct.ion of their lirw of action. Since the gradient or th<' teusil<' \\'ires is low, 011lv, it applies
(7.52)
7 Cross-span structures, poles and foundations
362
I
_..,,.__ _ _ Te-n-si-on-in_g_w_ir-es-~--A,, 3 3
5'
5
Contact wire -
/-
- - Transverse span wire -
,-
6'
6
4
________, .,__________ _ .( .., I' . 0
___
I 44'
/24
/4•2•
A2·
Figure 7.14: Horizontal catenary arrangement .
The gradient of the tensioned wire follows from (7.53) From the distance a 23 to the pole the difference between the height of support 2 and the attachment at the pole follows: (7.54) The rating of the support wires and ropes can be determined from the equation (7.49). The poles have to be rated for the forces H01 and H 23 respectively, which act at a height corresponding to the sum of contact wire height, the design height of the supports and the values hA and h8 . On tangent track horizontal registration, arrangements in accordance with Figure 7.14 are used. Where the distances between the individual supports do not exceed 20 m the stagger is distributed over several spans. Therefore, only vertical loads occur at the supports, the wind load excepted. Tensile forces and design heights can be approximated from the following: (7.55) taking advantage of the symmetries, n 1 should again be ~;elected between 10 and 15. The height at point 3 will be (7.56) The tensile force between 1 and 3 is
=
H13
H53 · Vlf 3 + by3/b13
(7.57)
and between 3 and 3' the force lfn
1
H, 3 · ln/ Jtf:i
+ l>'f:i
(7.58)
acts. The height of fixing at a pole finally is (7.59) The supports have to be rated with these forces and their heights of application. Frequently, several tensioning forces act at one pole. These forces have then to be combined geometrically. Details on calculation of horizontal registration configurations can be found in [7.15] and [7.16].
7.5 7.5.1
Rating of poles Introduction
The poles used for contact line installations can be classified as single pole, cantilever design even when lattice steel poles are adopted. The loading of the poles is characterised by the applied bending moments which must be restrained adequately. The rating of poles includes the determination of lengths, internal forces or moments and the selection or design of appropriate pole types.
7.5.2
Determination of pole length
Pole length determination must include allowance for support of overhead contact lines, the arrangement of traction power lines and the top of foundation level in relation to top of rail. For poles on open lines the height is determined by distance e between head of rail (TR) and top of foundation (TOF), contact wire height (CWH), system height (SH), distance between upper swivel bracket and suspension or termination of traction power lines (TPLH), required space for insulation of traction power line, additional length (AL) top of pole and the traction power line or the fixing of cantilever. AL is 0,10 to 0,15 in case of steel poles and 0,20 to 0,30 m in case of concrete poles.
Example:
Fore 0,70 rn, CWH = 5,50 m; SH= 1,80 m and AL= 0,10 rn a pole length of 8, 10 rn would result. Since pole lengths arc available in steps of 0,25 m or 0,50 m a length of 8,00 m is selected. Compensation is achieved by selecting the value e = 0,60 m for the construction of the top of foundation.
7.5.3
Loadings and internal forces and mo1nents
As st.ated previously, forc<)S front \,1riow; so111ces act 011 contact. line supports. Loads act.ing through the rn.11tilt•\t'ts i11cl11d<·· - loads frn1n contad lines, i1l(l11di11g d<·nd and wind loads ,\ltd
_ 7 Cross-span structures, poles ,1:ncl foundations
36-1
- dead loads of the cantilevers themselves (see 7.4.2.1). Loads acting at terminations include: - tensile forces resulting from the terminated contact line and - loads due to the dead weights of the tensioning equipment. At midpoints loads include: forces due to the midpoint anchors and - forces clue to the termination of the midpoint. Traction power line loads include: wind loads, - radial loads and - loads from intermediate or dead end terminations. At cross-span supports there are: - loads from head-span and cross-span wires. Loads from disconnect.ors supply lines and other equipment such as transformers and lighting equipment have to be considered when applicable. Dead loads and wind on the structural elements act in all cases. In accordance with the terminology used in civil engineering, loads can be classified as acting as permanent and variable actions. Dead weights and permanently acting tensile forces can be grouped under the first category; wind and ice loads under the second. According to the rules stipulated by European standards, the design loads of the actions follow from the permanent actions Fs,j and from combinations of variable actions Fv ,.i k
sd = L Fs,.i. rG + Fv,j. rQj
""'F L· V,J· · rvq I J· · WoJ·
(7.60)
j=2
j=l
where
l
and rQ are partial factors and \Ji 0 the combination factor. They are 1,35 for loads increasing permanent actions, ~(G 1,00 for loads reducing permanent actions, ~/Q 1,50 for variable actions, Wo 0,60 for ,vind, Wo 0,70 for ice. The moments and transverse forces at the top of foundation can be calculated in accordance with Figure 7.15. Loads perpendicular to the track result in the moment .\/\' and the transverse forces CJz, while loads parallel to the track produce the moment "t and the forces Qy- The force CJx represents the sum of the vertical loads. The moment J\Jx which represents a torque on the pole axis, may result from asymmetrical action of loads in relation to the pole axis. At the top of the foundation the vertical forces will he rG
i'G
11q
n1
CJxd =
L
'Yc;1, \ ~-
/;=]
+L
~(Qi
Vi
(7.61)
i=l
rc·prcsent t lw iudi\ idnal partial factors and \ 1, \ i tlw vertical loads, which result from ('qw1t io1t (,> 7) fo1 '-'·ires a11d coudll(:tors. Tll<' l
\\·here /ca· aucl
~,Q1
7.5 _Rating of pr~lf~s
z /er!Jen . ~....----- Y o trc1c1r 0'1cu1c1,
parallel to track
X
V; hyi
.,.,...Pole
~
--
Mz
Ox
Figure 7.15: Loads and internal forces and moments at an overhead contact line pole
Mx
the track result from n1
Qzd =
L
bc,kFH,zk
± ~/Q,kF\V,zk)
(7.62)
k=l
The forces FHk result from the contact lines and traction power lines in accordance with equations (5.10), (5.14) and (5.17). The forces Fw,zk are wind loads from equation (5.27) for contact lines. They may act in alternate directions. The forces in parallel to the track m1
Qyd
L (,c,iArsi
(7.63)
rQJF\\ .yi)
i.=l
are derived in most cases from terminations of contact line and traction power lines. Wind action only needs to be considered if no cantileYers are attached to the pole, e.g. poles for contact line terminations without suspension of cantilevers. The permanent maximum load is increased by a partial factor rG,i of 1,15. The bending moments, clue to the transverse forces and weight forces acting at distances Yi and 2.k from the poles central axis are 1111
11tc1 -
L hc:.i F,1,, i
'///.i
~iQ,iA\
\'i) . h, I
+ L '}Ci . \
i=I
I .
(7.64)
.lJ,
i=l
and Ill
!\!yd"·"·
L /,
I
/1.i
hc,1,,F111k
-,q.1.f\\',\/.) ·
/1zk
+ L ,·c1; /.:=l
· I 1.
· ~k
(7.65)
7 Cross-span_ structures, poles and foundations
366
I
9-----~ h ! \
I\\ \
I I I I I
\ \ \
0
-c:
::,
-c:
jox14
sf,
I
lo~,
Ox14/ /
Sy
,Ii('
' Sy Sz
1
2
Figure 7.16: Leg member forces of a lattice pole.
Figure 7.17: Bracing forces of a lattice steel pole
Loads due to terminations of contact lines and other loads may act eccentrically to the pole central axis and create moments lvlx around the central axis. For example, this applies to poles equipped with twin cantilevers, if the loads from the individual contact lines differ. If zk and Yi effect the eccentric load action, it applies n1
Mxd
=L
m1
bc,k · Fr-I,yk
± rQ,kFW,yk)
· Zk
k==l
+L
ho,iFH,zi
rQ,i,FW,zi) · Yi
. (7.66)
i==l
These internal forces and moments are used for rating of poles and foundations or for selecting them from available documentation of loading capacities. In the case of slender structures, e.g. H-beams, the deflections must be limited at contact wire height, in order not to impair railway operation.
7.5.4
Rating of cross sections
7.5.4.1
Introduction
The rating of cross sections applies the standards of structural design of steel and steelreinforced concrete structures for the individual types of poles including the selection of materials, e.g. the steel grades. Since the dead weights and wind loads affect the internal forces and moments, the determination of cross sections by itself is an interactive process. In the case of poles for contact lines, the loads clue to the overhead contact lines supersede the others, so iteration steps are limited. 7 .5.4.2
Lattice steel poles
The static system of lattice steel poles is formed by three-dimensional trusses. The individual members are esscutially loaded by axial ((\llsil<~ and compression forces and formed by angle sections . In the utse of comt11011l\· adopted desiµ,us with rectcrngular
7.5 Rating of poles
----"'---'-------------··----------------------------
367
cross sections, it is permissible to analyse the poles face by face by considering the faces as two-dimensioned truss-structures. In accordance with Figure 7.16 the leg member forces are (7.o7)
where lz and ly denote the distances between centroidal axis of the leg members. Compression forces receive a negative sign and tensile forces a positive. The bracing forces can be calculated according to Figure 7.17 based on [7.2] from (7.68)
and (7.69)
In equations (7.68) and (7.69) by,k and bz,i denote the pole width at the loading application points. ld is the system length of the bracings and byo, byu as well as bzo, bzu are the widths of the pole above and below the bracing being analysed. D.y and D.z are the increase of latitude. The factor m has the value 2 for single ·warren and 4 for double warren truss. Each structural member must be assessed to ensure that cross sections are able to withstand applied tensile and compression forces and that joint design is adequate. The introduction of European standardization requires consideration of ENV 1993-1-1 [7.12] which follows approaches different from previous design codes. For members loaded by the compression force Nd
Nd <
Xmin ·
Aetr · arfrYr
(7.70)
applies, where Xmin follows from 7.26, Aerr is the cross section, ar the yield stress and 'Yr the partial factor for material. In case of tensile forces
applies, where Anet is the net cross section of the member, au the ultimate tensile strength and 1 rvr 2 the partial factor, being 1,20 in this case. If only one leg of the angle is connected by one bolt then 0,9 Anet
(bi
<1) · f
(7.72)
follows ,vith b1 being the width of the connected angle leg, d the hole diameter and t the thidrness. In case of two and 111clt"e bolts, the 0,9 · Anet is found from (7.7:1)
7. Crns:-i-span structures, poles and foundations
where b2 is the width of the kg without the hole. The strength of a bolted connection having n 1 shearing cross s
N.sc1 ::;;
(7. 74)
n1 · O,G ar · As/1'P
The verification of bearing capacity for joints with n:i bolts is from Nbc1 ::;;
(7.75)
n2 · 2,5 n · a 1 · d · t/r'P
where o: is the lowest of the following values 0,75 · (ei/ d 0 - 0,5); a= 0,375 · (e2/do - O,~); { 1,0 · (e 3 /d 0 - 0,c)), where e 1 is the edge distance in direction of the force, e2 the distance of holes in direction of the force and e 3 the edge distance perpendicular to the direction of force.
Example:
The strength is to be determined for a member LlOO · 10, S235, buckling length 1,95 m, connected by 4 bolts M20 5.6 in both legs following the ENV 1993-1-1 approach. ENV 1993-1-1 approach: CTf = 235 N/mm 2 ; E = 210000 N/mm 2
a= 0,49 (buckling line c)
,\ =
>../(1r)E/ay) = l00/(1rJ210000/235) = 1,065
= 0,5 (1 + a(,\ -
X
= 1/ (1,279 + j(l,2792 -
0,2)
+ 5' 2 ) =
1,279
1,0652 ))
= 0,503
Nc1c1 = 0,503 · 1920 · 235/1,1 · 10- 3 = 206,4 kN Nzc1
= 0,9 (1920
388,5 kN
- 2 · 20 · 10) 355/1,25
N8 c1 = 8 · 0,6 · 300 · 314/1,1 = 412 kN
For e1
=
40; e2
Nbc1
=
60; e3 = 40 mm follows
= 4 · 2,5 · 0,884 · 20 · 10 · 235/1,1
· 10--3
0,884;
=
377 k:N
The compression loading limits the strength capacity of the pole. The permissible bending moment is given by multiplying the compression force by twice the pole width (see equation (7.67)).
In practice, pre-designed pole fmnil'l-C.s are used where the poles are characterized by their strength capacities in both directions. Figure 7.18 shows the permissible limiting moments according for lattice stc:el poles with base sizes of 600 · 800 mm and 800 · 1000 mm with different angle sections and pole lengths. Thereby it applies (7.76) or
fVf1c1/(J\.ifgr,y/1'P)
+ Jl/z/(1\/µ;
1
,z/1'1')::;; 1
The partial factor 1'P should to ll<' 1,1 in this ca'.,<'
(7.77)
7.5 Rating of poles
3G9
900 kNm
750
··1-->----"-
4;_,)& '.l&-
1
aa b,:., V+1a <5'
600.
v0
&cti. O;;
i
Ql
'J-7u'
()
,f2
<'el). :911)
Ql
D
~
.8
0 450 ·
m
:S ()
'5 C:
Ql
Q.
m Q.
300
cQl E 0 2 150
0
150
300
450
600
750
900
kNrn
1050
Moment perpendicular to small face
Figure 7.18: Permissible limit state moments for lattice steel poles.
7.5.4.3
Double channel poles
Double channel pole8 consist of two channels connected by stay plates, so that the channel spacing decreases towards the top of the pole. The spacing of the stay plates is approximately 500 mm (Figure 7.6). These poles possess greatest strength in the direction of their transverse axis. \i\Thile perpendicular to this direction only the bending strength of the individual channels is effective. Therefore, they are used where the loads act predominantly in one direction, such as in the case of suspension poles on open lines. The strength of such poles can be evaluated by treating them as Vierendeel-girders which are dealt with in [7.17]. At DB, poles with profiles lllO0. Cl20, Ul40 and exceptionally UlG0 are used. Figure 7.19 shows the permissible ultimate strengths. It has to be verified that
where rt' - 1, 1 according to the European stf~d st.ruct1m~ ;-wah·sis. Double c:hanud poles are connected to their foundations by 1\I:30 anchor bolts f01 UlO0 typt)S and l\L1G for Ul:20, UHO and U lGO types.
370
··---··--··-- ____ ··-·-·-·-- 7 Cross-span structures, poles and foundations
- -----
165
- r-- -- --------
150
135
-
25 120
~
Q)
E 105 0 E
~~
1""U 16o'
I'---_
r------......
U 140
~
-- ---
90
E
:.:J
~
I'--_ ......_
~
Q)
'ii,
.........___"
t--
c
1ii
........_______,__
75
U 120
......
......___
60
r---.....
.....
',
',
U 100
Y- -
-
45
s
5
6
7
10 11 8 9 Pole length above base -
12
13 m 14
Figure 7.19: Permissible limit state moments for double channel poles.
7.5.4.4
"' Figure 7.20: Designations in a cross section of an Hbeam section.
H-beam poles
Poles made of fl-beams in comparison to lattice steel poles and double channel poles require only a relatively low manufacturing input. They are especially suited for sites with limited space, e.g. in between tracks. However, their strength to weight ratio is low. They are weak in bending and suffer high deffoctzons at the same static loading capacity as fabricated sections. The deflection should be limited in the height of the contact wire in order to ensure the correct functioning of the overhead contact line. H-beams possess in relation to their transverse axis y y a considerable higher strength than related to their axis z z (Figure 7.20). To reinforce the weaker axis, two beams can be arranged in parallel and directly welded togd,her or connected by stay plates. Single H-beams possess a low torsional stiffness around their longitudinal axis. In case of poles with twin cantilevers, as pole type 4 according td Figure 7.4, the torsion of the poles has to be checked. It should not exceed 6° . According to recent design standards it has to lw prm<'tl. that
(7. 79) There ar is equal to the yield stress as well as Np1,11d
(7 80)
7.5 Rating of poles
371
T
11 11 11 11 11
11 11 11 11 11 JJ
u __ 620
-0-
-0-
'
I 0
0 'SI"
I -
-
-
-
I
-
-
f-
'
-0-
-0-
II
Figure 7.21: Design of base for poles made of H-bearn sections.
I
500
I
J\1ply,Rd
=
2 · Syar/,P
(7.81)
and
(7.82) are the internal forces and moments in case of complete plastic coHdition of cross sections. For H-beams the pt. order moments Sy and Sz may be obtained from
Sy
= b . t . (h I 2 - t I 2) + (h I 8
-
t) 2
2
. .5 /
(7.83)
and (7.84) In [7.18] these values can be fonud in tables. The dimensions b, h, I, and s nw he taken from Figure 7.20. Figure 7.21 shows the desigll of the base for poles nrnde from H-beams. In addition to the bending, the torsion must be verified. I-I-beams are weak iu torsion because they are open sections. The torsional rotation can be obtained according to [7.19] for a H-beam with a length h nwasured in degrees from 17
= Ii
· 1\lxf ( 1,3 .!1 · C) ( 180 /rr)
(,'
·17 0
mrn
N-rnrn
i\'/ lllll 1-')
.\
(7.8D)
7 Cross-span str\1ctuE~!s,_ poles and foundations
Table 7.4: Concrete for steel-reinforced concrete poles. Designation Nominal strength /lwN S(!rics :-:t1(!11gl h /Jws N/mrn C35/45 C45/55 C55/65 C75/95
2
N/mm
45 55 65 95
2
Value for calculation /Jn N/uun 2
50 60 70 100
27 30 33 42
where the torsional modulus J1, is
,ft
(2·b·t'3 +(h
2t)·s:J)/3
(7.86)
The shear modulus G is 8 · 104 N /mm 2 in case of steel. 7.5.4.5
Steel reinforced concrete poles
The external loads of steel rein.forced concrete poles result from the clauses 7.5.2 and 7.5.3, which can be used to determine the required equivalent working load. It is the horizontally acting total force at the top of the pole without wind load on the pole itself according to (7.87) where ]\![yd and ]\l[zd can be calculated from (7.64) and (7.65) respectively and h is the pole length. With this value, the required pole can be selected from manufacturer's catalogues or selection tables for pre-stressed or slack-reinforced poles. The cross sections must be designed in accordance with the relevant standards. The moments are determined from the equivalent working load and the wind load or from individual forces according to the 2nd order theory. For concrete poles manufactured in a workshop, EN 12 843 applies. Acrnrding to EN 12 843 concrete of class C35/45 is the minimum that can be used for concrete poles. For pre-stressed spun concrete poles high strength concrete classes C55/65 and C75/95 are also used. To determine the most unfavourable stresses the following loading cases have to be assessed: Loading case 1: perrnanent loads, - Loading case 2: normal loading and Loading case 3: loadings due to trn.nsport and erectwn. The vertical loads and the tensile forces of the conductors act as permanent loads. In the case of normal loading the wind load on conductors and on the pole must also be taken into account. The acceptable internal forces and rnonwnts for loading cases 2 and 3 rrrnst be determined for the ultimate limit st.al.(' of resistance using the theoretical values or the strength, which can lw ohtaiued h_,. di,iding the nm11.inal strength .BvvN of conr:r-ete according to Table 7.4 hy 0,7 aud ti\(' yield strength /-is for c·onnet<~ or reinforcement. sted by the pa.rtial factors and :s, n~spectinily, <1<·(ording to Table 7.5 liur)s 3, 4 ,rnd 5.
,<·
7.5 Ratir1:12 of poks
373
Table 7.5: Partial factors related to the limit state of strength Loading case 2 Normal load
Loading case 3 Transportation and erection loads
l'f l'f
0,80 1,20
1,00 1,00
l)
1,50 1,40
1,30 1,25
1,25 l's For deflection analysis acc. to the 2 order theory
1,10
For strength analysis Pres tressing acting favourably acting unfavomably
1 2
Concrete Spun concrete
3 4
l'c
I)
l'c
Concrete and pretension steel
5
nd
6
Concrete and spun concrete
l'c
2)
1,20
7
Concrete and pretension steel
l's
1,15
-·
1) related to 0,7 /JwN 2) related to 0,85 times the maximum internal moments. 1 - - - - -~s 1 ;....----r-~ Ys I
C
Q ~
/
e!
I
o..
E
ai a,
I
s::i
8?
u5
I
2.c
~~
/
I I
§ e! /, Ow '--____,___......,__--c-_ -2
-3,5 ·10 3
Concrete strain Eb
Figure 7.22: Stress-strain curve for concrete for calculation of the permissible internal moments and the limit condition of resistace (parabola-rectangle-diagram).
5-10-- 3 Steel strain ±: Es
Figure 7.23: Stress-strain curve for concrete steel and pre-stressing steel for calculation of acceptable internal moments and of deformations at limit state of resistance.
For concrete, a stress-strain curve in accordance with Figure 7.22. for concrete and prestressing steel with a bi-linear line (according to Figure 7.23) can be assumed where the modulus of elasticity Es may be used without any modificaticm. In the case of pre-stressed poles, no concrete tensile stresses are permissible under the action of penmtrH'llt loads as well as under action of -10 % of the rnn1t1<'11t due to 11onnal loading. The internal forc<'s aud mome11ts for the limit stat<' uf resistance is d<~tenniuecl adopting times the normal load taking into accouut the pole clefonmttiu11 (2 nd order theory). An unintended tilting of the unloaded pole of G mill/Ill should lw ass1u11ecL Th<' tilting takes also care of effects due to curvatme because of unequal heating . The effects of pole deformation may be neglected if the additional t110J1t('11t clue to ckforn1at.iot1 and tilting is l<~ss titan ;i % in the cross S<'diou at tllf' top of frn111clation or is less t.ha.11 10 %1 it1 case of the most 1rnfm·om,llilf' .sc•di011. r<'SJ><'< ti\<'h Fm this proof,
,r
7 Cross-spaustructures, poles and foundations
374
an estimation on the safe side suffices. These conditions are mostly met by overhead contact line poles. Improved engineering design of steel concrete poles, especially spun concrete poles, should eliminate possible damage such as has occurred at times in the past [7.10]. The following items have to be duly considered: A sufficient helical reinforcement is necessary to distribute tensile stresses at the surface. The helical reinforcement should consist of ribbed concrete steel and should be provided independently of the static demands. The reinforcement should be as follows: 5 mm diameter wire and a maximum pitch of 60 mm, with 4 mm diameter and a pitch of maximum 40 mm with diameters up to 3 mm and a pitch of maximum 30 mm. The wall of the concrete must be sufficiently thick, being at least 40 mm. The clearance between unidirectional reinforcement rods needs to be only half of the rod diameter, with exception of the overlapping section. It shall be at least as wide as the diameter of the maximum aggregate size. The concrete coverage shall be at least 15 mm above the helical reinforcement or 20 mm above the pre-stressed steel. The water to cement ratio is reduced below 0,4 during the spinning process. Spun concrete poles are produced using casings that can be divided along longitudinal joints in which the pre-formed helical reinforcement is arranged first and then supplemented by the slack or pre-tensioned longitudinal reinforcement. In the case of pre-tensioning, a head is put on each rod. Poles for overhead contact lines have sockets and other elements for connection of contact line components arranged along the reinforcing. After preparation of the reinforcement the concrete is poured in and the casing is bolted together. The reinforcement rods are pre-tensioned with stresses up to 800 N/mm 2 • The number of revolutions during spinning depends on the diameter of the pole and the casing. Centrifugal acceleration between 10 and 50 g are envisaged. After 12 to 15 minutes the spinning process is finished and the casing with the spun pole is stored in a heating chamber where, during a short period, steam is guided along the outside of the casings. The temperature in the heating chamber should not exceed 50°C and the poles should remain in the steel casings for 24 hours. Heat treatment at higher temperature was used in the past, however, this proved to be one reason for longitudinal cracks [7.10]. Poles manufactured to the procedure described above attain 70 % of their nominal strength during storage in the casing. Reliable production and good engineering is a precondition for long service of the poles without premature damage. 7.5.4.6
Deflection
Under loading, all supports are deformed since they are made of elastic materials. Relatively wide sµread la.ttice steel poles are rigid st.rnctures and only in the case of tall head-span poles will visibl(\ deformation occur. Frequently, these poles are raked opposite to the direction of loading, such thnt the pole stands vertieally after application of the load. Double channel pol<'s, ,ne also nda!i\·dv stiff in the direction of their main loadiug . Generally, verifi<'atio11 oft lte del'miu,11 i()n is 110!. n<~!·<~ssarv. In c011t rast, with
7.5 Rating of poles
·-- . -· ·-- .
· - - · - - 375 --
relatively weak poles such as H-beams, the limitation of the deformation may govern the design of the section properties. In general, the deformation in a height hp above the pole base of a pole with a variable section modulus along the vertical axis loaded by bending will be:
!7, = ~
hp
j !11Ji:)/I(:r) · :i:d:c
(7.88)
0
According to Figure 7.15 the coordinate :c counts from the point where the deforrnation has to be determined. Since the integral in (7.88) cannot always be solved analytica.lly, numerical methods, especially computer programs were developed to determine the deformation for poles according to (7.88). Reference is made to [7.2]. For poles made of H-beam sections, the moment of inertia I is constant along the beam and (7.88) can be solved analytically. According to [7.13] the deflection at a point a caused by the application of the force F at a height h above the foundation base is 3
a, ( -a,) 3-+ h h
Fh [ .fa= .6 Ely 2 and due to a moment
f, = ::: [I
- 2
3]
(7.89)
*+ m']
(7.90)
and due to the uniformly distributed load for a beam with a total length l
J, = 24q~Iy [3 -
7+ m ']
4
(7.91)
In the case of contact lines the following cases are of special interest: Deflection under wind load at the height hp of the contact wire. DB limits this deflection to 25 mm. Deflection under permanent load at the height of the catenary wire. DB limits this value to 1 % of the height of catenary wire. Deflection under maximum load at the height of the catenary wire. DB limits this value to 1,5 % of the height of catenary wire. Using the designation according to Figure 7.15 the following formulae ca.11 he used for the calculation of the deflection: At the height of the contact wire under wind load: 2 [ Fe Aw hew
.fcww
(/1,c \
hew /3)
Fr,:w/1.f:w(/11,: - hcw/3)
3 + Fcww · 2 h'cw /3 + Fpwhf-;w(h/2- hcw/3 + hfw/(12h))]
(
· 238/I
At the lwight of the ('atcuarv wire under pcrma!lent loads fcArr
-
[ Fc:i\112
h,Lj;{ + Fcwir · hi:w(hc:A
+ (\" · .1J1; + \ i-. · //1-:)hf:A/2]
· 238/I
hew /3)
+ F1:11h(, (h,,:
7.92
hc:1\/3) (7.9:3)
7 Cross-span structures, poles and foundations
At the height of the catenary wire under maximum loads .fcA(lHW)
+ Fc:Aw) · 2 · hf;A/3 + (Fcw11 + Fcvvw) · h}~w(hcA hew /3) + (Fm-1 + FEw )hi:A (hE - hc:A/3) + Fpwhf:A [h/2 - hcA/3 + h~A/(12h)] + (ilom, · Yk Vi-:· '.IJE)h~A/2] · 238/ I
[(FcAH
(7.94)
In equation (7.92) to (7.94) the values Fcw 11 , FcAH and FEH can be obtained from (5.10) or (5.11), Fcww, FcAw and FEw from eq. (5.17) as well as VoHL and VE according to (5.6). FEH, FEw and VE are related to the feeder lines supported by the pole. In these equations the modulus of elasticity for steel was used with 2,1 · 105 N/mm 2 ; for I the unit is cm 4 as used mostly in standard tables. The forces have to be inserted in kN, the lengths in m. The results have the unit mm. The example given in clause 7.8 demonstrates the use of these formulae .
7.6 7.6.1
Subsoil Introduction
Foundations of overhead contact line supports shall be designed so they transfer the various structural loads, that result from different loadings, reliably into the subsoil without unacceptable movement of the foundation bodies. Since the subsoil conditions at the support sites are critical to the selection and the design of foundations, they must be known sufficiently when rating the foundations. Subsoil investigations provide this information by classifying the encountered soil according to the standard series DIN 4022, BS CP 2001 or other National standards and preparing the soil characteristics needed for selection and design of foundations. Soil mechanical engineering classifies the subsoil which forms the crust of the earth, as undisturbed soil (loose rock), rock (solid rock) and soil .fill. Loose rock is a natural heap of mineral particles. Without applying any force, it can be separated into the existing particle sizes. In the case of rock, applying of force is necessary for separation. This classification is characteristic for civil engineering and differs from terms currently used in geology.
7.6.2
lJndisturbed soil
7 .6.2.1
Classification
Undisturbed soil has been f'mrned by an ancient geological process on earth, by chemical and physical weathering all(! deromposition of rock or it may have an organic origin. For the purpose of civil engi1H~<'.ring, undistmhed soil is dassified as inorganic- or organic, Inorganic subsoils <·cmsisL ol' twn main tq>es, no11-rnhesive, friable soils and cohesive soils, They are disti1:guisli<·d h\ p,Ht.icle sizc~s i\lost of the subsoils <~nco1111t<~rcd in the
7_.6 Subsoil
Table 7.6: Particle si½es of uon-cohcsivc and cohesive soils. Name
Symbol
Particle si½es in mm
Non-colw:-;iv<\ :-;oil:-;
blocks
y
above 200
Ra.Ilgc of sicv<'
stoucs
X
63
to 200
particles
gravel
G
2
to 6:3
c:oa.rsc gravel
medium gravel fine gravel sand coarne sand medium sand fine sand
20 6,3 2,0
gG mG
fG
to 63 to 20 to 6,:J
s
0,06
t,o
2,0
gS mS
0,6 0,2 0,06
to to to
2,0 0,6 0,2
fS
u
0 ,002 to
0,06
coarse silt, medium silt fine silt
gU mU fU
0,02 to 0,006 to 0,002 to
0,06 0,02 0 ,006
clay (finest)
T
Cohesive soil
silt
Range of fine particles
below
0,002
field are mixtures of different particle sizes and will be classified depending on the main proportion.
7.6.2.2
Non-cohesive, rolling soils
Non-cohesive subsoils are characterized by particle sizes above 0,06 mm. They include non-cohesive groups consisting of sand, gravel, stones and blocks (Table 7.6).
7.6.2.3
Cohesive soils
Cohesive soils are characterized by particle sizes less than O,06 rn m which cannot be distinguished by the unassisted eye. Cohesin' soils arc also distinguished by their grain sizes (Table 7.6). A rn:b:ed granulated 80it is cousidf!r<)d as Hon-cohesive if it contains less than 15 % by weight of particle sizes less than 0,06 mnL The non-cohesive comporwuts determine the characteristics of the mixed grarmlat,ed soil. Othervvise the soil is classified as a cohesive soil with coarse-part ide additives.
7.6.2.4
Organic soils
Oryanu: soils contain residues of dccornpos<~d plaILts and ani1nal orgauisu1s. 13csidcs pund,v 01gauic soils, mix<'d soils having clwrnc.<·ristics do~;c to clay il1tcl silt with substauti,d organic coutcllt are called ·111:w{ Sine<' th<' rnmpn\ssihilit, oft liese t,vpcs of soil is high they are ILOt suited as a subsoil to canv loads. D11<' to ! 11<' det<·rniini1tg ,,ffect of tl1e orga1tic cornpo1ie1tts Oil tli<· soil clliuacL<'ristics 11011-col1<'si,·,, ,111d rnll<'siv<' soils with lll11~;id,·1<'d ilS org;11tic soils
7 Cross-span structures, poles and foundations
7.6.3
Rock
The term rock includes all solid subsoils which form the hard and solid part of the Earth's crust. DIN 4022 classifies the different types of rock. For the loading capacity their degree of weathering is important.
7.6.4
Soil fill
Soil .fill is commonly encountered in artificially constructed railway embankments. For these engineered embankments, the soil material is selected carefully to achieve a compact and dense structure. The material gained from tunnel boring is often used in embankments. Foundations to be installed in compacted railway embankments should be designed to suit the soil density, which can be measured by probes.
7 .6.5
Soil investigation
The supports of an ov·erhead contact line extend over a long section, where varying soil conditions may be encountered. Soil investigations are aimed at obtaining the necessary information to enable a decision to be made on the best-suited type of foundations and their design. The soil investigation forms a basis for static analysis of foundations. For this reason, the extent of soil investigations and the depth of individual studies should be appropriate to the needs of the design. The depth of soil investigation depends on the type of foundation and the applied loadings. If good bearing soil is found up to the terrain surface, it might be sufficient in most cases to carry out soil tests to 1 m below the expected sub-base of the foundation. Since soil investigations are rarely carried out at each individual support site, the foundation design is based on available documentation and on specific assumptions. The adequacy of the assumptions must be verified during foundation installation. Soil investigations may not be waived when it is obvious that very low-bearing soils, such as mud, will be encountered. In such cases, the depth of good-bearing soil layers must be investigated. Inspection of line sections may serve to decide on the type of soil investigation. Preliminary information on soil may be obtained from the installation of the permanent way or for any other structures that the infrastructure manager may have. Soil investigation methods must use appropriate methods to obtain soil samples to determine the density of soil layers.
7.6.6
Methods of obtaining soil samples
7.6.6.1
Introduction
The methods of obtaining soil samples are stanclarized in DIN 4021. In the case of contact lines, it is sufficient to gain disturbed samples, since an investigation of soil characteristics in laboratory t<)sts is uot H~quired Tlw disturbed soil samples are used to st11dy the sequence ol'soil la_vers, l heir ho1111cl;ui()S. tlic type of layers, tlw distribution
7.G Sub:-;;oil
Helical auger lo collect the soil
Edge to cut the drilling Edge to cut the soil
Figure 7.24: Helical auger.
of particle sizes, the consistency, the ground water table and the organic components. For this purpose investigations of quality level 4 according to DI\f 4121, Table 1 are sufficient in all cases, however, they may not be performed on each line nor at each site.
7.6.6.2
Investigation boring
In the case of soils, non-lined investigations boring of 300 to 500 mm in diameter will yield suitable results for the definition of soil types, water table, the stiffness a.nd the density of the stratification. For investigation boring, low-duty boring machines with auger diameters of 100 to 150 mm are used as well. For lifting the soil, helical augers are adopted (Figure 7.24). These devices may be used to im·estigate less firm and watercontaining layers. Depths np to 12 m can easily be reached. The soil samples gained from the bore holes will be mixed up. The profile of layers can be seen where the soil adheres to the individual pitches of the auger.
7.6.6.3
Investigation by probes
Probe boring using a peuctrnmeter with a grooved rod to take distmbcd samples of soil are suited for soil iuvestigaLiou of sites along a contact line. This pcne.lnJ·111.der cousists of a grooved probe rod, ha,ing a longitudinal groove 1,0 m in length at its end. After driving the probe, a soil sampl<' is gathered iu the longit uclinal groov<' and recovered when hauled from the bor<' l10k Sands in the grouud water table urn not IH' n\covered since they are washed out Fm such tvp<~s of soils, prnbC's ell<' adopt<'d <'
.,I ,I
.1,'1
.. ··-~----·-·-···· 7_ Cross-span structures, poles and foundations
380
Table 7. 7: Data of driven probes according to DIN 4096, part 1. Device (DPL) Light-duty probe Medium-duty probe (DPM) (DPM-A) Heavy-duty probe (DPH)
Weight of hammer in kg
Falling height in m
10 30 30 50
0,50 0,20 0,50 0,50
Table 7.8: Guiding data for the correlation between number of blows and stratification density. Type of soil, Stratification Sand, medium density dense Sand-gravel mixture medium density dense
Number of blows n 1o Light probe Heavy probe
> 15 ::: 30
> 5 ::: 10
> 15
> 5 > 18
_I)
1) light-duty probe not suited
7.6.7
Probing
7.6. 7.1
Introduction
Depending on the application, probes may be either driven or compression types. The , soil penetration resistance is recorded during probe penetration into the soil. Probing complements soil profiles by quantitative findings on the stratification density and may be sufficient to obtain the necessary data for design of foundations in many overhead contact line installations. Probes are available in many types; those that are used for overhead contact line construction are discussed below. 7.6.7.2
Driven probes in accordance with DIN 4094
Dimensions of driven prDbes and instructions for use are given in DIN 4094. Under specified conditions, a rod with a cone-type end is driven into the soil the number of blows necessary for an penetration of 100 mm (n 10 ) being counted. This number represents a reference for the density of stratifaction and consistency of layers explored. Table 7.7 reveals some charactc~ristics of the various driven probes. For foundations of contact lines, the lmN-dutv driven probe (DPL) is used in most cases. The results of probing
7-(LSubsoil
381
Table 7.9: SPT probing in non-cohesive and cohesive soil. Standard P<\Ilet.ration Test. in Cohc8ive soil
Non-cohesive soil N11111lwr of blows n:w 0 to 4 4 to 10
10 to 30 30 to 50 > 50
7.6.7.3
Stratification
Number of blow8 n:io
very loose loose medium dense dense very dense
t.o 2 to 4 to 8 to 15 to 30 > 30
0 2 4 8 15
Consistm1c:e very soft soft medium stiff very stiff hard
Standard Penetration Test
The Stanclanl Penetration Test (SPT) was developed in the USA and is now used all over the world. Firstly, a shuttered borehole is drilled. Then a cylinder with 35 mm internal diameter at the end of a rod is inserted into the hole and driven to a depth of 150 mm by a hammer weighing 63,2 kg and falling from a height of 760 mm. The number of blows necessary to indent the probe by 300 mm is counted (n 30 ). The soil sample, pressed into the cylinder during indentation, can be recovered and studied. According to [7.21] the correlation between condition of strat~fication of non-cohesive soils as well as consistency of cohesive sods is proposed as shown in Table 7.9.
7.6.8
Evaluation of soil investigation
Soil investigations may be evaluated according to DIN 4022 and recorded in bore hole logs. Specifications for designation and description of soil types are given in DIN 4022 or BS CP2001. They will not be repeated here. For details see [7.2]. Information on assessment and classi.fication of rock and its weathering conditions can be found in [7.22]. The range between loose and solid rock is divided into six classes, which are distinguished by the degree of ,vcathering of the rock and the particle compound; they are named as follows: ·w 0 umvcatlwred rock, w I minor ,veathering, w:2 modcrn.tdy weathered, w: 1 highly weathered, w,1 complete!~, weathered, //Ir, soil. Rod: fm1,nduJ.wns, <'. g. ro('k anchors. can lw llS<'d ill weathering conditions of w 0 to w2. Grn1uHl water ,\tld soils can attack co11cretc, if t,lte,· ('011tain frc<~ acids, sulphides, sulplt,itcs, 1mtgncsit11t1 salts, a1t1111oniurn salts or gn',ts<' and oil. Grnund wafer danger to 10·11ndr: ('clll lw recognized IJ,v ;\ <' tak<'Il ,ltHI iuv<'stig,iU~d i11 Llie !alioraton T,li>i<' , IO s111111t1c1ti/.<'S illforn1;t! ion (>11 lw::unl,, of 1111111:11,r/ ·w11l1T lo 1·onud1'
382
-------- -
and foundations - - - - 7-Cross-span - - ~ -structures, - - - ~poles ~-----
Table 7.10: Assessment of degree of aggressivene::,s of ground water and soils of predominantly natural composition. Degree of aggressiveness very heavily aggressive slightly aggressive heavily aggressive pH-value below 4,5 pH-value 6,5 to 5,5 pH-value 5,5 to 4,5 Types of water: chalk soluble carbon acid (CO2) in rng/1 determined by the marble test ammonium (NHt) in mg/I magnesium (Mg 2+) in mg/I sulfat (Soi-) in mg/I Soils: sulfat (So~-) in mg per kg air -dry soil
7.6.9
40
40 to 100
above 100
15 to 30 300 to 1000 200 to 600
30 to 60 1000 to 3000 600 to 3000
above 60 above 3000 above 3000
2000 to 5000
above 5000
15 to
Soil characteristics
Since the design 0f foundations for contact lines closely follows overhead power line technology, the soil characteristics specified in the relevant standard EN 50 341-1 [7.23] and EN 50 341-3-4 [7.4] are used as a basis. Table 7.11 presents those characteristics which are also relevant for contact lines. For individual types of soil the unit weight, the angle of internal friction and the permissible soil pressure are listed. The use of these values requires compaction of soil after placing of fill material. The permissible soil pressure depends on the unit weight. The permissible pressure according to Table 7.11 applies to a depth of 1,5 m. The permissible at rises by the additional loading according to the increase in depth multiplied by the factor K, (Table 7.11). perm at
= perm a 1,5 + (t - 1,5)1'B · K,
(7.95)
In the case of ground water, the unit weight reduced by buoyancy according to Table 7.11, column 3 is considered.
7.6.10
Practical application
vVith respect to the most frequently adopted foundation types for contact line installations, namely concrete block and driven pile foundations, the soil investigations are aimed predominantly at bearing capacity in case of compression; depth of good bearing soil strata and their density of stratification and investigation of suitability of soil for pile driving to the depth of expected pile length. Accordingly the low-duty driven probe in accordance with DIN 4094 and the penetrometer with grooved probe (see clause 7.G.G.3) a.re adopted.
7.6 Subsoil
383
Table 7.11: Soil characteristic for design of foundations acc. to EN 50341-3-4. 1 Type of soil
2
3
Unit weight force 1'E (Values for design) natmally with humid bouyancy kN/m:3 kN/m 3
4
5
6
Angle of internal friction
Coefficent
degree
Permissible soil pressure at a depth of 1,5 m kN I m-·)
200 1 ) 300 1) 400 21 400 2 ) 400 2 ) 400 2 )
3.5
I{
Undisturbed sails Nun-cohesive suits 1 sand, loose 2 sand, semi loose 3 sand, dense 4 gravel, bolder, uniform 5 gravel-sand, uniform 6 bolder, stones, macadam, graded Cuhesi>ue sails 7 very soft· 8 soft (easy to kneed), purely cohesive 9 soft, with non-cohesive additions 10 firm (difficult to kneed), purely cohesive 11 firm, with non-cohesive additions 12 stiff, purely cohesive 13 stiff, with non-cohesive additions 14 hard, purely cohesive 15 hard, with non-cohesi,e additions Organic soils, and suds with organic additions Ruck with considerable fissuring or unfavourable stratification in sound, not-weathered condition with minor fissuring or favourable stratification Made up gr-o'll,nd and fill uncorupacted embankment
compacted embankment.
17 18 19 17 18 18
9 10 10
30 32,5 35 35 35 35
16 18
8 9
0 15
0 40
1 2
19
10
17,5
40
2,5
18
9
17,5
100
2,5
19
10
22,5
100
3
18 19
10
22,5 25
200 1 ) 200 11
3 3,5
27,5 30
400 21 400 2 )
3,5 4
9 10 11
11
18 19
5 to 16
0 to 7
1000
25
3000 6 to 10
10 to 25
5 5 5 6
1
15
20
12 to 16
--1
30 to 100
2
classification according to type of soil, density of stratification and consistence
l) permissible soil press11t<' ano1ding to DB's internal standard 3 Ebs 02JJ1 02 2S0 kN/lll 2 2) permissilik soil prcss11te au1,1di1tg to DB's internal standard 3 Ebs 02 01 .02 -100 kN/rn 2
384
___________________________ 7 _Cross-span structures, poles and foundations
J::
Ol C
~ ~
a::
0)
C
ii
2
Q
0 J::
ci Q) 0
E
a_
J, c5 I
Figure 7 .25: Soil investigation for a pile foundation.
Table 7.12: Nur,nber of blows for the low-duty driven probe for the example according to Figure 7.25. Depth Number of blows n10 4 2 2 0 to 1,0 4 6 8 10 10 12 13 1,0 to 2,0 12 16 14 20 20 18 22 24 20 20 2,0 to 3,0 19 24 24 22 26 23 23 24 28 30 3,0 to 4,0 30 32 26 30 32 38 40 42 38 40 4,0 to 5,0 36 40 40 46 50 53 52 55 54 56
A initial indication of the soil conditions to be expected can be obtained from the railway infrastructure manager and in the case of new lines, from the companies installing the permanent way or by bridge management. Further knowledge can be gained by inspection of the line observing height and slope of embankments, sections with surface rock, wetlands, drainage installations and the like. Based on the line inspection and on the type of foundation envisaged, the e.Ttent of soil investigations can be determined. Soil investigations should aim at reliable and continuous information about the soil conditions along the line. Investigations at each individual pole site would be an optimum from the technological point of view but expensive and time-consuming. With respect to the continuous character of railway lines, the soil investigation may be limited to areas of varying soil conditions and on sites for dead-end or mid-point anchor poles. Tested by the low-dnt:v driven probe more than 8 blows for 100 mm depth of penetration indicates bearing soil Probing should then be continued for auotlwr 3,5 m in case of suspension poles and -L:""i 111 i11 cas<\ of dead-end poles and stop1wd when a depth of 0,5 to 1,0 m below the point of pile is re;--1c:hed. Figure 7.25 shows llH' rn<'1,hod of probing at a dead-end pole site and Table 7.12 the 1111mber of blows achi<'\()d with the low-duty probe. Mon' than 8 blows were struck to read1 0,5 rn below !l1C' s11rl',1c<' TIH'refore, 1.lw probing was nrntirttH:d to a. depth of
7.7 Foundations
385
Ql
Figure 7.26: Designations for foundations for contact line poles. e = difference in height between rail head and top of foundation E = insertion depth of poles inserted into the foundation :r: = dimension between top of foundation and lowest level of transition to soil t 0 = embedding depth of foundation
G,O rr1. Bdmv l,G m the soil structure is medium to dense and below 3,0 m it is dense to very dense with a permissible soil pressure of 250 and 400 N/mm 2 , respectiwly. This data is typical and at DB standardized foundations are specified for these reference data. For design of a pile foundation the strata O,G m below surface may be considered as presenting good side-bearing capacity.
7. 7 7.7.1
1
F oundations Basis of design
The type of foundation depends 011 the pole type, the loading, the soil conditions and the available technology for foundation installation. Since there is a close correlation bet·ween pole and foundation design, the selection of poles has to be carried out taking into account foundation aspects. The foundations for contact line poles may be classified as compact foundations characterized by supporting the pole by a single foundation body. Loadings in these cases are n1c-1.inly monH:'nts and also horizontal and ,ertical loads. Thr structmal loads are tnuismitted to the subsoil by soil 7n·cs.s'11,re in the foundation sub-base or b,· latend C/1,rth reswtance. depending on the typ<~ of compact frJ11ndation. For design of foundatious, the transition to new approaches is under way \\·here the vcrific;-1!,icrn is no longer carried out for working loads but for limit loads and limit strength. This design approad1 also forms the basis of new European Civil Engineering sta!l(lcmls. The lirml strength of a fomufotwn is a criterion, which when exceeded means that the foundation will 110 longer fulfil its task or will faiL At the 111oment 110 such draft standards are m ailablc so conventional rnethods liased on working loads are still used. Tlie t<'qttin!uwnts and basis of design ha,c! IH'<'ll r<'lated to st,;-rndard E:"J iJO 110. The desig1121.t.ions gin'll in Figme 7.2G have been intrndt1< eel for merll('ad <·011tact line foundations, according to DB's pntd,ice.
7.7.2
Block foundations without steps
(,'1111.111'!!' /Jlod· /11undn.lw11s mII<' l!lld<1!iOll t.vpe.
7 Cross-span structures, poles and foundations
386
N
..c:
(J
Figure 7.27: Load carrying performance of a block foundation without steps.
p·to
the soil pressure on the base as well as the lateral earth resistance add to the limit strength. The earth resistance may be considered in accordance with the stratification density and the soil characteristics, only where the soil remains undisturbed. In the case of prismatic foundation bodies where the height is essentially larger than the width, the loading is mainly transmitted by lateral constraints (side-bearing). As a first approximation the contribution of the sub-base may be neglected. Using the described approaches, foundations consisting of concrete bodies with circular cross sections may also be verified. In accordance with Figure 7.27 the external loading is transmitted to the subsoil by the pressure between the foundation face perpendicular to the loading direction and the soil. If a linear increase of permissible soil pressure with the depth is assumed P·t
CTperm
(7.96)
as well as a pivot at a depth of two thirds of the foundation depth a parabolic pattern of soil pressure with depth results expressed by a
- 2 pt
+ 3 p/ t 0 · t2
(7.97)
The total reaction forces above and below the pivot can be obtained as 2/3 to
F0
=
b
I
2/3 to
crdt
2 (-2pt+3p/t 0 -t)dt
b /
0
/ 2 ·b·p 427t 0
(7,98)
4/27t6 · b · p
(7.99)
0
and /,
adt '2/:Ho
=b
/
'2/:l lo
(-2pf;
+ 3p/t 0 · t 2 )dt =
7.7 Foundations_ ______________________________________________ ----·---------·-·----------~38~7
Location I, II
Location Ill
Location IV
--------. Oz
'
N
N
.c::
Location I
?
.c::
O,Sm
~~---
0 0
Figure 7.28: Arrangement of block foundations.
The distance between both forces F0 and Fu results from the centres of pressure s 0 and su, which ar'e obtained from
I
2to/3
s0
=
F,b
u(2/3to - t)dt
=
pb F,
0
0
I
2t 0 /3
0
(4t 2
-
4/3to · t- 3t 3 /to)dt
= to/3
(7.100)
0
and
b
Fu
to
I
u(t
2to/3
b 2/3 t 0 )dt = !!__ Fu
J (4/3 t tu
0 ·
t
4 t2
+ 3 t 3 /t 0 )dt
2-to/3
11/48 t 0
(7.101)
The distance of the centres of pressure is then
s
(l/3
+ 11/48) · t 0 = 9/16 t 0
(7.102)
Moreover, it is assumed that the horiwntal loads are counteracted by friction in the foundation faces in parallel to the loading direction. Therefore
Qz(hz
+ 2/3to)
Since Qz · h./,
111y
= Aly
=
F;) · s
·-
9/16 · 4/27 p
ti· b =
1/12 JJ
ti· b
it is obtained
= pt6 · /J/(12 + 8 t, 0//1z)
(7.103)
For applications at DB hi 8,0 is assumed which applies to poles 011 open-route li•ies outside stat.ions. According to Figure 7.28 four conditions can lw distinguished concerning the location of a blork foundation: in a plain and th<' foundation edge is more than 0,8 m from th<' edge of embankment; i11 a plain and t.h(' f
7 Cross-spai_1_J,_~~t~_l_1:_ires, poles_ and foundations
3:::::8-=--8___________________ ----------- _
Table 7.13: Permissible moments for block foundations in kN -m: M p - 10:3 · b · to · K, (to)/ K 2 (to); Location I Location II Location III towards away from track track pl)
Width b (m) 1,00 1,00 1,00 1,20 1,20
0,125
0,1
0,1
0,1 t2
K1 (to)
t5
ta
K2 (to)
12,3 + t 0
12,3 + t 0
(to+ :r2) 2 12,6 + t 0
37,0 52,0 70,0 125,0 158,5
29,5 41,5 56,0 100,0 127,0
40,5 55,0 72,5 125,0 156,0
")
-
Location IV towards away from track track 0,1
0,1
12,75+fo
+ .r-1)2) 2 l'.3,05 + lo
13,2 + t 0
28,-5 40,0 54,0 97,0 123,0
39,5 -53,5 70,0 121,5 151,5
27,5 38,5 52,5 94,0 119,5
0
Uo
t5
Depth
to (rn) 1,60 1,80 2,00 2,30 2,50
1) pin N/(mm 2 -m)
- in the edge of embankment and - in the embankment. When determining the permissible loading, the effect of arrangement on the resistance has to be taken into account. In this case the equation (7.103) is transformed using CTperm = p · to and t t 0 + X1 with the result fi![y
= CTpermt 2 · b/(12 + 12xi/hz + 8t/h
2 )
(7.104)
In the first case t = t 0 and x 1 = 0, 2 apply and p - 0, 125 N/(mni-m) is assumed. In the second case t = t 0 + x 2 applies if the loading acts towards the track, otherwise t = t 0 as well as (:z: 1 + :r 2 ) instead of x 1 . The value pis assumed to be 0,100 ~/(mm 2 · m). In the third case t = t 0 + 1: 2 /2 applies if the loading acts towards the track otherwise t 0 = t 0 as well as (.1: 1 + :x: 2 ) instead of :i: 1 . Table 7.13 shows permissible moments for block foundations used by DB.
7. 7.3
Block foundations with steps
Block foundations with steps, also called gravity or slab foundations, are selected if the soil is not suitable for side-bearing foundations. High external loadings may require stepped block foundations as well. Therefore, this foundation t,pe is often adopted for head-span poles. In this case, the loading is mainly transmitted to the soil b,· the bas· the ,.veight forces of a soil body start i11g at t!H· fo11 udatioll base with an angle 1 t o,,·,uds the vertical
7.7 Fouudatious
389 _ ____,_ 0
R,Z
ffiMy
l--2-Figure 7.29: Load carrying performance of a block foundation with step. z
A
-Y
...
by/3 -
... I
b
Figure 7.30: Permissible range of eccentricities ey and ez of the total load Q 1: in a rectangular foundation base.
and ending at the f:lurface. This soil body has the form of a truncated pyramid; the volume of the foundation body itself being deducted. \i\fhen the moments Aly and 11fz act as loads the force Q resulting from the soil pressures in the base must. be within an ellipse according to Figure , .:30, if the safety margin against overturning should be at least 1,50. For rectangular base areas, this will be con1pliccl with if
(7.105) ,vlwrc r\ - M, /Qx a.ncl Cz - i1lz/Qx- The resulting force Q, 1 is the sum of all vertical loadings. The theoretical soil pressur<' in accordance with
(7.106) 1w1, not. cx.c<~cd tlu~ pcr111issibl<' values . \Yitlt the soil types often encount<\rccl in rnihvay c11, irn1111w11L fottndat.ions an'
_
Exa1nple: The p<~nuissibk IH!ttdi11g 111omc11t. is t.o Ii<) dct.cnui11<'d for ,t stepped block foundal i
________ 7Cross-spau structures, poles and foundations
390 2,65 I 2,25
0
N
c5
)
Figure 7.31: Example for a stepped block foundation
4,60/ 4,20
Table 7.14: Factor ,.,,n to take care of the effect of bank gradient on the strength of stepped block foundations. (For used symbols see Figure 7.32.) Slope of hank Distance Ratio of height of bank/ B n to depth of foundation G /to from 1,00 1,50 2,00 m to 1,10 1,07 1,04 0,25, 0,50 1,20 1,15 1,09 0,50 0,75 0 1,30 1,22 1,13 1,0 2 1,0 1,08 1,06 1,04 0,25 0,50 1,17 1,12 1,07 0,20 0,50 0,75 1,25 1,18 1,11 0,75 2 1,0 0,25 1,06 1,05 1,03 0,50 0,40 0,50 1,13 1,09 1,05 0,75 0,75 1,19 1,14 1,08 2 1,0 0,25 1,05 1,03 1,02 0,50 0,60 0,50 0,75 1,09 1,07 1,04 1,14 1,10 1,06 0,75 2 1,0 1,03 1,02 1,01 0,25 0,50 0,80 0,50 1,05 1,04 1,03 0,75 1,08 1,06 1,04 0,75 2 1,0 1,01 1,01 1,00 0,25 0,50 1,00 1,02 1,01 1,01 0,50 0,75 1,03 1,02 1,01 0,75 2 1,0 1,10 1,00 1,00 1,00 0,25 2 1,0 Weight force of the concrete body
QxB
= (4,60 · 4,20 · 1,25 + 2,65 · 2,25 - 1,55) 22,0 = 777
kN
Weight force of the soil body As
= 4,60 · 4,20 = 19,32
A 0 = (4,60
m2
+ 2 · 2,7 tan 27,5)(4,20 + 2 - 2,7tan 27,5)
QxE = [(2,7/3)(19,3
+ 51,9 +
J51,9 · 19,3)
= 51,9 m 2
:34,1] · 18,0 = 1053 kN
' !
7.7 Foundations
391
Figure 7.32: Stepped concrete block foundation installed in an embankment.
Total weight force Permissible moments: Eq. (7.105) yields: ez = bz/3
1830 kN
= 1,533
m; ey
= by/3 = 1,40
m Mzperm = 1,533 · (1053 + 777) = 2806 kN · m Myperm = 1,400 · (1953 + 777) = 2562 kN · m The soil pressure is obtained from (7.ll0) a= 1830/((4,60 - 2- 1,533) -4,20)
= 284 kN/m 2
and a= 1830/(4,60 · (4,20 - 2 · 1,40))
If aperrn
= 250
= 284
kN/m 2
kN/m 2 , then from eq. (7.111) at first ez
,respectively.
= 1,428
m and ey
= 1,304
m result,
yielding to Mzperm
=
2615 kN · 111 and Myperm
=
2248 kN · m.
If stepped block foundations are installed close to or directly in embankments, their loading capacity is reduced depending on the installation conditions and the gradient and height of the embankment. The permissible moments determined by the approach described above have to be reduced by dividing with the relevant factors K,n riccording to Table 7.14. The symbols used follow from Figure 7.32.
7. 7.4
Driven pile foundations
Driven pile foundations represent an economic alternative to concrete foundati,ms cast in-situ and are suited especially for locations with deep good side-bearing soil or ,vith a high groundwater table, which otherwise would require a costly shuttering of the excavation and drainage of ground water. A variety of steel piles selected according to the pole type have gained increasing importance. They are also suitable in case of narrow site locations. They requir<' vrry limited excavation and minimise soil distmbance and stratification in critical embankments. Steel piles adopting (sheet wall) profiles in accordance with Figure 7.33 can be advantageous for lattice steel, doublC'-channel and bolt-mountPcl H-lwarn poles. :\ concrete li<~ader on the piles accornnwdatt•s tl1<· h,tSf\ attachment of the pok \\'itl1 standard andtor holts. l'lte pile sections ,m• s<'lect<'d in acccmlm1cc with tlw lo;idir1g T110 ir1dividual
_? Crn~~~pan structures, poles and foundations
392
0 N
C
r--i
I
I
YI,
r
I
'
,(,,0-"
-
I
-
I
I
0
"
i
I
,,lb
!
I,
I
~
I
' If?
!j
Giil ~ Giil Giil
~
~~ ~~
~
Figure 7.33: Driven steel pile with a concrete header.
1,60
/
Concrete pole ,Adjustment of height Cast-in mortar Pole Adjustment of height
0
0 0
2
·o 0
CX)
Terrain surtace o
0 r--
/
Cast-in mortar
2 0
0 lD
- Prefabricated concrete part Residual soil part
Driven tube
Figure 7.34: Spun coucrete pole set on a
-- Driven pole
Figure 7.35: Spun concrete pole on a sheet wall pile with a tube wekkd Oil pil<~ top.
Figure 7.36: Spun concrete pol<) ius<:rt<)d into a driven ste
393
Table 7.15: Earth pressure coefficient
\i for profiles in banks according to (7.31]
depending on the angle of internal friction
° ° ° ° ° ° 0 0 0 0 0
° ° ° ° ° °
40
35
70,923 34,051 21,592 14,929 11,062 8,570 6,840 5,572 4,599 3,826 3,193 · 2,660 2,201 1,796 1,428 1,076 0,587
18,817 13,226 9,951 7,822 6,331 5,228 4,375 3,690 3,124 2,643 2,224 1,848 1,502 1,163 0,671
Angle of internal friction i.p in ° 25 20 15 10 30
8,743 6,982 5,737 4,807 4,080 3,492 3,000 2,577 2,204 1,866 1,548 1,231 0,750
5,075 4,319 3,723 3,235 2,823 2,464 2,143 1,848 1,566 1,277 0,821
3,312 2,926 2,595 2,304 2,039 1,792 1,552 1,299 0,883
2,321 2,099 1,894 1,698 1,504 1,295 0,933
1,704 1,564 1,420 1,262 0,970
5
0
1,291 1,191 0,992
1,000
profiles can be welded together to form a twin profile pile for transfer of high loads acting simultaneously in two directions. For concrete poles, driven tubes are used onto which the pole is fixed [7.11], (Figure 7.34). Since the diameters of the tubes have to be less than the inside diameter of the spun concrete poles relatively thick-walled and therefore, heavy and expensive tubes are necessary. As an alternative sheet wall profiles with a tube welded at the top can be adopted. These form a favourable combination of spun concrete poles and high-capacity driven pile foundations (Figure 7.35). After alignment the space between concrete pole and steel tube is grouted with mortar. The concrete pole protects the steel pile against corrosion in the air /soil transition area. Any other corrosion protection measures are unnecessary. As an alternative design, concrete and H-beam poles can be in.,erted into steel tubes with wider diameters (Figure 7.36). The space is filled with concrete or by griL In the case of steel tubes accomodating steel poles suitable corrosion protection is necessary. For verification of the geotechnical efficiency of a pile foundation the method, in accordance with [7.32] can be used. The method was developed for design of large-size piles in harbours an
7 Cross-span structures, poles and foundations
394
Terrain surface
E
><
MmaxZ
Earth bearing resistance
Deflection
Area of bending moment
Soil pressure
Figure 7.37: Basis of pile design according to [7.32].
assumptions was confirmed by many applications under test conditions without any failure of the pile foundations. The approach uses the earth resistance fw = 'YE · Ap, where the earth pressure coefficient Ap in flat terrain follows from
Ap
= tan 2 ( 45° +
(7.107)
where
x~
+ 3 · b · x~ = 6 · Qz,R/ fw
(7.108)
The transverse force Qz,R represents the sum of horizontal forces and correlates with the moment at top of the piles by Qz,R
= Jvlz/ hz
For pile foundations with loadings in direction of both profile axis the corresponding resultants must be used for Jv[z and Qz R· The maximum moment is '
iWmax,Z
= Qz,R(hz + Xz + Xm) - fw(b · .1:~/6 + .T~j24)
(7.109)
Often the second load decreasing term in (7.109) is deleted and in a simplified manner the following is obtained (7.110)
where xz is the thickness of the non-bearing soil strata. For the embedding depth into the bearing soil t 1~ = 1, 2t 0 applies in accordance \Yith [7.32], where t 0 is received from (7 .11 l )
7.7 Foundations_·_ _ _ _ _ _ _ _ _ _ __
_____________________________:3~9~5
which is solved numerically. The total pile length is
L = tc
+ Xz + 1; -
0,20 m
(7.112)
where it is assumed that the pile ends 0,2 m below the top of foundation. In practice, the pile length may be rounded to 0,5 m steps where up to 0,15 m rounding down is acceptable. In case of suspension poles, the minimum embedding depth tr,; should be 3,0 m, in case of intermediate poles of overlaps 3,5 m and 4,5 m in case of dead-end poles. If the poles situated in an embankment are loaded parallel to the track the design may be carried out by adding an ideal non-bearing soil stratum with the thickness z' = 0,945/n where 1/n is the gradient of the embankment. In embankments ·with a height greater than the piling depth in a level terrain minus 1,0 m the embedding depth is not taken from tE = 1,2 t 0 but from tc = 1,7 t 0, if the direction of loading is at right angles to the embankment. In addition to the geotechnical reliability the strength of the steel must be verified, where the bending stress for S235 in accordance with EN 10 025 should not exceed 140 N/mm 2 . Furthermore the displacement at the pile head can be obtained from
where h 2 is the ideal height of application of the resulting transverse force. The horizontal pile displacement should be limited to 30 mm or 0,005 times the pile length, where the lower value will apply. The pile design according this approach is shown in an example in clause 7.8
7. 7 .5
Anchor foundations
For overhead contact line poles, anchors are designed to react to longitudina.l loadings being permanently present in a given direction, e.g. loadings from terminations of contact or catenary wires which otherwise would lead to high loadings of poles and their foundations. As can be seen from Figure 7.38 anchor foundations are loaded by anchor forces in the vertical direction by the vertical component F;w and in horizontal direction by the horizontal component FAH· The resistance against being pulled out is created by the dead weight of the foundation and the skin friction against the surrounding soil: (7.114) with
volurn<' of fou11dation,
- unit weight of foundation, e.g. of concrete, - friction area, - skin friction value. Ti Tlw friction value T, dqlrnds on tlw material used for foundation and from the type of soil. Table 7. Hi lists d;-1 La for friction brtwcrn conn(\te ,wd soil.
7 Cross-span structures, poles and foundations
--
Direction of line
I
l
FAH
I
Iim
I
C\J
0
0
l[)
0
iii
Type of soil
~ - + - - - ·~-
.
I..
\
I-
Table 7.16: Friction values between soil and concrete.
.. I
Figure 7.38: Foundation for stay (guy) anchors.
sand, very dense sand, dense sand, medium dense sand, loose clay, hard clay, semihard
Friction value 2 T, in kN/m
20 15 10 5 12 6
The anchor foundation is sufficiently designed in view of uplift if
The factor VA is at least 1,5, if FAv is the working load. The horizontal loading is counteracted by the passive earth pressure, which may be assumed as increasing linearly with the depth
e = !'E · t · (Ap - Aa)
(7.116)
where !'E is the unit weight of the soil and
Ap - tan 2 (45
+ tp/2)
(7.117)
tan 2 (45
tp/2)
(7.118)
Aa
In these equations tp is the angle of internal friction (see Table 7.11). In total, the earth pressure of a body with the depth / 0 and the width h is then
E
0,5·,E·ti·h·(Ap-\,)
(7.119)
The stability is ensured if the resistance modified by the L1ctor vA is higher than the horizontal loading and an overturning of the anchor foundation could occur only at a loading moment multiplied by the factor u/\
(,.120)
7.8 Exampk
Table 7.17: Data of overhead contact line type Re 330 (DB). M0ssengm Cont.act \\·ire wire CuMg AC-120 Bz II 120 Mass per unit lengt,h 1,07 1,06 kg/m Diameter mm 13,2 1-1.0 kN 27 21 Tensile force Wind loac! 1 l per unit length N/rn 13,3 1-1, 1
Return
feeder Al240 0,67 20,3 4,8 17,4
Parallel feeder Al240 0,67 20,3 8,5 17,4
1) clamps and droppers considered accordingly
An anchor force FA of 40 kN acts at an angle of 50°. In this case FAv = FA· sin50° = 30,6 kN and FAv =FA· cos50° = 25,7 kN. The soil is assumed to be medium densely stratified sand characterized by 'YE = 16 kN /m 3 ,
Example:
Fic1 = 22 · 1,8 + 10 · 5,72 = 104,7 kN From (7.117) and (7.118) it is obtained
Ap - Aa
= tan 2 (60) - tan 2 (30) = 2,67
as well as according to (7.119)
E
0,5 · 16 · 1,8 2 · 1,2 · 2,67
= 83, 0 kN
The safety margin against pulling out is UA
= 104,7 /30,6 = 3,42
and against overturning
// = (104,7 · 0,5 + 83,0 · 1,8/3) / (25,7 · 2,0 + 30,5 · 0,5) = 1,53 The anchor foundation complies with all requirements.
7.8 7.8.1
Example Data of contact line
The desiqn of cantzleven;, poles and foundations will be demonstrated with the example or a pole for a high-speed line equipped with fk 330 type contact line and swivelling uuitilevcrs using the new European standards where applicable. Solll<' essential data of th<' contact li11(' arc given iu Table , 17 Tll(' following additional infor1u;1Lio11 also applies
7 gro~~~span struc.tures, poles and foundations
398
0
co_
---------
Fcw,w+Fcw,1-1
0
0
0
C\I_
0
C'J_
0
lD
""· CD
cri
CO
3,70
'
/ W,
Figure 7.39: Dimensions of and actions on an overhead contact line pole.
D
Contact wire height 5,300 m System height 1,80 m Stagger 0,30 m Track Radius 10 000 m Span length 65 m Wind velocity 37 m/s 2 Wind pressure: 37 /1,6 = 855 N/m 2 Weight force of contact wire per unit length 22,5 N/m The pole carries a termination for the return feeder. Dimensions and forces are shown in Figure 7.39. In the example only the numerical data is given in case of intermediate steps of calculation. Units are used as noted above.
7. 8. 2
Design according to recent European standards
7.8.2.1
Loadings
\·ertica.1 loads (see (5.6a)) rnntact line equipment: Cantilt•ver: Parallel feeder line:
Return feeder: Equipment of pole head:
VoHL l'c;AN
Vr.,, 1
,.cRC '
:22,5 · 65 G,7 · 65
(, ·- c·-;) ), I
.
)/)
:_
1465 N 1500 N 440 N 220 N 1000 N
7.8 Example
399
Horizontal loads (see (5.17)) Catenary wire: FcAw 14,1 · 65 920 N Contact wire: Fcww 13,3 · 65 865 N Parallel feeder: FFLW 17,4 · 65 1130 N Return feeder: FRcw 17,4 · 65/2 565 N Pole (HE-B260): Fw 1,7 · 855 · 0,26 · 8,5 3215 N Horizontal components of conductor tensile forces (5.10), R = 10 000 m, b = ±0,3 m Catenary wire: FcAH 21000 · 65/10 000 140 N + 4 · 0, 30 · 21 000/65 390 N 530 N 175 N Contatct wire: FcwH 27 000 · 65/10 000 500 N + 4 · 0,30 · 27 000/65 675 N Parallel feeder: Fpur 8500 · 65/10 000 55 N Return feeder: FkcH 4800 · 65/(10 000 · 2) 15 N Termination of return feeder: FRcL 20 · 240 4800 N In case of design according to European standard [7.12] for steel structures ENV 1993-11, the partial factors and combination factors for actions have to be specified. They are: Permanent actions
= 1,35
(if increasing the stress) 'YG = 1,00 (if decreasing the stress) Variable actions 'YQ = 1,50 Combination factor Wind W0 0,60 Ice Wo = 0,70 'YG
The dead weight of conductors, cantilevers and poles as well as the radial forces of conductors are considered as permanent actions, while wind and ice are variable actions. The combination factor has to be taken into account if ice loads are present. The loadings calculated above have to be multiplied by partial factors which are carried when calculating the internal forces and moments. 7.8.2.2
Design of pole
Shearing forces and bending moments at base of pole Qyd
Afzd
1,35 (530 + 675 + 55 + 15) + 1,50 (920 + 865 + 1130 + 565 + 3215) = 11 763 - 11,8 kN 1, 35 (1465 · 3,7 + 1500 · 0,54 · 3,70 + 530 · 8,2 + 675 · 6,4 + 5[> · 9,0 15 · 8,20)
+ 1,50 (920 · 8,2 + 865 · 6,4 + 1130 · 9,0 + 565 · 8,2
+ 3215 · 8,5/2) CJ7,c1 Afyd
86 220 Nm 86,2 kNrn 1,35 · 4800 - 6480 N = 6,5 kN 1,35 · 4800 · 8,2 53140 N 5:3,2 kN
7 Cross-span structures, poles and foundations
400
Vertical forces - increasing the stress Qx = 1,35 (1465 + 1500 + 440 + 220 - decreasing the stress Qx 1,00 (1465 + 1500 440 + 220 Calculation of strength Yield stress ur = 235 N/mm 2 ; r'Mo = 1,1 vVp1z = 1283 · 10 3 mm 3 (see [7.18]) lilp1y = 602 · 10 3 mm 3
= 6245
N
+ 1000) = 4625
N
1000)
= 6,3
kN
4,6 kN
Plastic strength, axial force (see (7.22)) Npl,Rd
= 235 · 11800/1,1 = 2520 kN.
Plastic strength, bending moment (see (7.23)) 235 · 1283 · 10 3 /1,1
J\;{plz,Rd J\lfplz,Rd
·=
3
235 · 602 · 10 /1,1
= 274 kN · m, = 129 kN · m.
From (7.21) it follows 6,3/2520 + 86,2/274 + 53,2/129
= 0,73 <
1,00
The strength is higher than the internal forces and moments. The suitability for use, namely the deflection, has to be verified without any partial factors. Verification of deflection The deflection perpendicularly to track is critical. The deflection under wind action at the height of contact wire is according to (7.92)
fcww
=
[o,920 · 6,4 2 (8,2 - 6,4/3)
+ 1,130 · 6,4 2 (9,0 -
+ 0,865 · 2 · 6,4 3 /3 6,4/3) + 0,565 · 6,4 2 (8,2 -
6,4/3) 238 + 3,215 . 6,4 2 (8,5/2 - 6,4/3 + 6,4 2 / (12 - 8,5))] · 14 9 1170 - 238/14 920 = 18,7 mm~ 19 mm< 25 mm The deflection at the height of the catenary wire under action of permanent loads is according to (7.93) fcAH
= [o,530 - 2 - 8,2 3 /3 + 0,675 - 6,4 2 (8,2 - 6,4/3) + 0,055 · 8,i\9,0 8,2/3) + 0,015 · 8,i3 - 2/3
+ (1,465 · 3,7 + 1,500 - 0,54 · 3,7)8,2 2 /2]
· 238/14 920
674 · 2:38/14 920 - 10,8 mm < 0,01 · 8200
= 82
mm
.
7.8 Example
401
0 0
CX) ~
8,t ~~----;::~~=--=;-,~ 0
co
C')
300
----
4
900
1150
r:1
1450
-H-------"---1
Figure 7.40: Geometry of cantilever.
3700
The deflection at the height of the catenary wire under the action of maximum loads is eventually according to (7.94) .fcA(IHW)
=
[1,450 · 2 · 8,2
3
/3 + 1,540 · 6,4 2 (8,2 -
+ 1,185 · 8,2 2 (9,0 -
+ 0,580 · 2 · 8,2 3 /3 8,2/3 + 8,2 2 /(12 · 8,5))
8,2/3)
3,215 · 8,2 2 (8,5/2 (1,465 · 3,7
6,4/3)
+ 1,500 · 0,54 · 3,7)8,2 2 /2]
· 238/14 920
2382 · 238/14 920 = 38,0 mm< 0,15 · 8200 = 123 mm
7.8.2.3
Cantilever
As an example, design of a cantilever made of aluminium is verified for a push-off support. Figure 7.40 shows the cantilever geometry. Length of tubes and dimensions Length Dimension Top tube 3700 mm 42 x 4 Cantilever tube 4285 mm 70 x 6 Diagonal strut 1657 mm 26 x 3,5 Registration tube 3951 mm 55 x 6 Two combinations of loads are verified vVind had, no ice load (loading case 1) Half of design wind load, ice accretion on catenary wire and cantilever (loading case 2) Vertical loads Contact line equipment without ice: Contact wire: Catenary wire with ice accretion:
I ()!IL I ·cw
1465 N 10, 7 · 65 "/00 N .IJc.\E = 5 + 0, 10 · l:-1 + 10,6 lc:\E - 17, 0 · 65 - 1105 N proportionate urntile,er dead weight I~, \N - 750 .\! prnportionate cantilner d<'ad weight. with i< <': \<·\Nice 8:>0 \l
17 N/m
7 Cross-span structures, poles and foundations
-102
- Horizontal loads Without ice (loading case 1) With ice (loading case 2): Catenary wire: Conductor diameter: dE = [6, 4 · 4/(1r · 7500) + 0,014 2 ] 0 ,50 = 0,0358 m ~ 0,036 m FcAw = 1,0 · 855/2 · 65 · 0,036 = 1710 N Contact wire: Fcww = 0,50 · 865 = 435 N The loadings have to be multiplied with partial factors. Verification of top tube 42 x 4, AlMgSil, F31 Internal forces at top tube (see (7.11)) Loading case 1: Ftop = ((1465 750)1,35-3,70 (530-1,35+920·1,5)2,16)/2,16 = 7200 N Loading case 2: Ftop = ((1465-1,35 + 750 · 1,35 + 340 · 0,7 · 1,5 + 100 · 0,7 · 1,5) · 3,70 (530 · 1,35 + 1710 · 1,5)2,16)/2,16 9195 N. Internal forces at diagonal strut (see 7.15)) Loading case ·1: Fn = ±(865 · 1,5 + 675 · 1,35)/ + (3,7 /2,16) 2
J1
= ±1115
N
Loading case 2: Fn = ±(435 · 1,5 675 · 1,35)/ J1 + (3,7 /2,16) 2 = ±790 N Internal moment at the top tube at attachment of the diagonal strut (see 7.16) and Figure 7.40) Loading case 1 (decisive) JYJ8 = 1115 · 3,7 · 0,6 · 3,1/(3,7 2 + 2,16 2 ) = 420 Nm Equation (7.21) applies to the strength in case of loading by axial forces and moments, if the shearing force is low. Npl,Rd can be obtained from (7.22) using err = 260 N/mm 2 Npl,Rd = 477,5 · 260/1,1 = 113 kN. The value l\llpl,Rd results from (7.23) and Table 7.3 J\;{pl,Rd = 5,798 · 260/1,1 = 1,37 kN · m. Then, it is obtained 7,2/113 + 0,42/1,37 0,37 < 1,0 . Therefore, the strength of the top tube is verified. Verification of the cantilever tube 70 x 6, AlMgSil, F31 Internal forces at the cantilever tube (see (7.13)) Loading case 1 (compression loading) FA (1465 + 750)1,35J,--i_+_(_3-,7-/-2,-1-6)-2 (865 · 1,5
675 · 1,35) / J~1_+_(_2-,1-6/-3-,7-0-)2 = -7840N.
Loading case 2
F.\ = -(1465 · 1,35 + 750 · 1,35 + '140 · 0,7 · 1,5)/1 + (3,7 /2,16) 2 (435 · I, 5 + 675 · l,~15) / J1 + (2,16/3,70) 2 Loading case 2 is decisive. Verification according to (7.25) ,vithout bending moments. sk - 4280 mm; 1 = 12,73 nun; 1\ 1280/22.7:3 - 188;
-
-8200N.
7.8_ Example_ - - - - -
------- ..
----····
J7o
X = 188/ (1r · 000/260) 3,65 according to (7.28) 2 , = 3950/17,45 = 226
X = 226/(1r · )70000/260) = 4,38 according to (7.28)
+ 0,21 (4,38 X = 1/(10,6 + J(l0,6 2 -
¢ = 0·,5 (1
0,2)
+ 4,38 2 )
= 10,6 according to (7.29).
4,38 2 )) = 0,049. With ky = 1,50 eq. (7.25) yields 2210/(0,049 · 923,6 · 260/1,1) + 1,5 · 915 · 10 3 /(14 778 · 260/1,1)
= 0,21 + 0,39 = 0,60 < 1,0 Therefore, the strength of the cantilever tube is verified. - Verification of the diagonal strut 26 x 3,5, AlMgSil, F31 Internal force in the diagonal strut: -1115 N. Bk = 1662 mm; ·i = 8,13 mm; ,\ = 1662/8,13 = 205; X = 205/(1r · J7o ooo/260) = 3,97 ¢
= 0,5 (1 + 0,21 (3,97 -
X = 1/(8,76 + )(8,76 2
0,2)
+ 3,972 ) = 8,76
.3,97 2 )) = 0,060 N8 c1/NRc1 = 1115/(0,060 · 247,4 · 260/1,1) 0,32 < 1,0 Therefore, the strength of the diagonal strut is verified.
7.8.3
-
Foundation
At the time of writing no final drafts for European .standard.s on foundatwns based on advanced design methods are available. Therefore, the conventional design procedure is adopted here where the loading is determined without partial fa,ctors. For this example, a driven pile foundation vvith a special H-hearn steel wall pile Psp370 (steel grade S235) is adopted. The data a.re: lVz
= 2290 · Hf1
rnm:i
fY
=
fil/v
= 804 · 10:l
111tr?
fz
=
Eff('.Ctive width o,:38
!IL
42 3G0 · 10:i 15 280 · 10:i
rnrn· 1
rnuf1
7 Cross-span structures, poles and foundations
-10-1
Site: Plain terrain, bearing soil: sand, 1,0 top of foundation Loading Qy = 8,0 kN Qz = 4,8 kN
J\17, ll1v
111
= 59,3 kN · m
below surface. Surface of soil 0,5 m below
hz = 59,3/8,0 = 7,40 m hy = 39,4/4,8 = 8,20 m
39,4 kN · 111
Resulting moment: !11R = )59,3 2 + 39,4 2 = 71,2 kN · m Resulting horizontal force: QR = J8,0 2 + 4,8 2 = 9,5 kN Effective height for action of force above bearing soil hR
= 71,2/9,5 + 0,5
1,0
= 9,00 m
.
Unit weight of soil 1 = 10 kN /m 3 ; angle of internal friction rp = 30° Specific soil pressure according to Table 7.15: ,\P = 3,0; depth of maximum internal moment (see (7.108))
t~ + 3 · 0,38 · t~ = 6 · 9,5/(10 · 3,0) = 1,90 This yields tm = 0,95 m Embedding length (see (7.112))
t~(to
+ 4 · 0, 38)/(to + 9, 00)
Therefore, Embedding length Total length of pile (7.112) Stress of pile, permissible
t0
- 4t~(tm
+ 3 · 0, 38) = 0
~
2, 75 m tE = 1,2 · 2,75 = 3,30 m L = 3,30 + 1,0 + 0,5 - 0,2 140 N/mm 2
~
4,60 m
+ 8,0(0,5 + 1,0 + 0,95) = 78,9 kN · m 39,4 + 4,8(0,5 + 1,0 + 0,95) = 51,2 kN · m 78,9 · 10 6 /2290 · 10·3 + 51,2 - 10 6 /804 · 10 3 = 98
59,3
lWz
A1y er
N/mn/ < 140 N/mm
Displacement of top of pile (see (7.113)) fz
=
8,0 · 10 3 /(210 000 · 4,2350 · 10 4 ) - (7,4 + 0,5
·
[(7,4 + 0,5
+ 0,65 · 3,30) 2 · 7,4/2 + 7,f3/6]
+ 0,65 · 3,30? /3 . 10 9
2,90 mm
.fv
4,8 · 10· 1/ (210 000 · l ,5280 · HY1 )
·[(8,7 5,20
+ 0,65 · :J,30f3j;3
(8,7
+ 0,65 · 3,:30) 2 · 8,2/2 + 8,il/6]
rtlltl
Tlw founclrttion con1pli(1s wich all the r<~q11ire11w11ts.
· 10 9
2
.
7.9 Rdet<\llC<\s
7.9
References
7.1 IEC 826, Loading and strength of overhead trarnm1ission lines. IEC Genf, 1991. 7.2 Fischer, R.; KieBli11g, F.: Fischer, R.; KieBling, F.: Freileitungen, Planung, Berechnung, Ausfiihrung (Overhead contact lines, planning, analysis and design). 4th edition, Springer-Verlag, Berlin, Heidelberg, New York 1993. 7.3 ENV 1991-2-4: Eurocode l: Basis of design and actions on structures, Part 2-4: Wind actions, CEN Bruxelles, 1994. 7.4 EN 50 341-3-4 : Overhead electrical lines exceeding AC 45 kV. Part 3-4: National normative aspects for Germany. 2001 7.5 I<.ieBling, F; RuJrnau, J.: Eislasten und ihre Auswirkungen auf Zuverlassigkeit und Auslegung von Freileitungen (Ice loads and their impacts on reliability and design of overhead power lines). IWAIS 1993, Budapest 1993. 7.6 DB: German railway directive Gbr 997.0101 - Oberleitungsanlagen (Overhead contact lines). 1997. 7.7 Bauer, K.-H.; I<.ieBling, F.: Fiihrung einer Bahnstromleitung am Oberleitungsgestange ( Construction of overhead traction power lines on contact line poles). In: Elektrische Bahnen 78(1980)10, pp. 257 to 260. 7.8 Brandt, E.; FieB, H.-J.: Analyse und Ursache von Betonmastschaden (Analysis and reasons for damage at concrete poles). In: Elektrizitatswirtschaft 85(1986), pp. 312 to 315. 7.9 Conrad, K.-H.; iu1.: Sanierungsverfahreu fiir schadhafte Betonmaste (Methods for repair of damaged concrete poles). In: Elektrizitiitswirtschaft 85(1986) pp. 89 to 94. 7.10 Wagner, C.: Ursache von Langsrissen in Betomnasten uncl daraus abzuleitende Produk-
tionsmafinahmen (Reasons for longitudinal cracks in concrete poles and consequences resulting thereof for production). In: Elektrizit~itswirtschaft 85(1986)2, pp. 95 to 97 7.11 Bauer, K.-H.; Stotz, W.: Rarnrnrohrgriindungen fiir Betonmaste (Driven tube foundations for concrete poles). In: Elektrische Bahnen 78(1980)10, pp. 260 to 264. 7.12 ENV1993, Bemessung und Konstruktion von Stahlbauten, Teil 1-1: Allgerneine Benwssungsregeln, Bemessungsrcgeln fiir den Hochhau (Design of steel structures, Part 1-1: General design rules, design for buildings). German edition, Beuth-Verlag, 1D9~L 7.13 Dui>l>el: Taschcnhuch Maschinenbau (IVIed1anical cngi11Cf!ring hand hook, 11th edition). Springer-Verlag, Berlin Heidelberg - New York, 1970. 7.1-4 J\/t;111a.1111, S.: Die grafisdw Bcst.i11111nmg dn Qtwr- uud 11 id1tscill~ingcu bci Fa.lulcitungen fiir 15 kV und lG,7 I-(7, (Graphical dd<~nnination of !wad span aud cross span wire length for AC 15 kV 16,7 [l7, rn11t.act lines). In: Signal tllld SdtiS Lo 11:>8 and 7(1%'.l)I, pp. 2f> to :l2
406
7 Cross-span structures, poles and foundations
7.15 Sachs, K.: Die ortsfesten Anlagen elektrischer Bahnen (The fixed installations of electric railways). Verlag Orell-Fi.issli, Zi.irich - Leipzig, 1938. 7.16 Siiberkriib, M.: Technik der Bahnstrom-Leitungen (Technology of overhead contact lines). Verlag Wilhelm Ernst & Sohn, Berlin, 1971. 7.17 Petersen, C.: Stahlbau (Steel structures). 3rd edition, Verlag Vieweg, Braunschweig, 1993. 7.18 Sclrneider-Biirger, M.: Stahlbauprofile, (Sections for steel structures), 21st edition. Verlag Stahleisen, Diisseldorf, 1996. 7.19 Hiitte I, Des Ingenieurs Taschenbuch, Theoretische Grundlagen (The engineer's hand book, Volume I, 28th edition). Verlag Wilhelm Ernst & Sohn, Berlin, 1955. 7.20 Grundbautaschenbuch (Soil mechanics hand book, 3rd edition). Verlag Wilhelm Ernst & Sohn, Berlin, 1980. 7.21 Terzaghi, K.; Pech, R.: Bodenmechanik in der Baupraxis (Soil mechanics in civil engineering p1:actice). Springer-Verlag, Berlin Heidelberg New York, 1961. 7.22 Heitfeld, K.H.: Ingenieurgeologische Probleme im Grenzbereich zwischen Locker- und Festgestein (Geological engineering problems within the transition between loose soil and rock). Springer-Verlag, Berlin Heidelberg New York;, 1985. 7.23 EN 50 341-1: Overhead electrical lines exceeding AC 45 kV. Part 1: General requirements - common specifications. 2001 7.24 Mohr, 0.: Abhandlungen aus dem Gebiet der technischen Mechanik (Basics on technical mechanics, 3rd edition). Verlag Wilhelm Ernst & Sohn, Berlin, 1928. 7.25 Frohlich, H.: Beitrag zur Berechnung von Mastfundamenten (Contribution to the calculation of tower foundations, 3rd edition). Verlag Wilhelm Ernst & Sohn, Berlin, 1936. 7.26 Paschen, R.; Bliimel, W.: Beitrag zur Bemessung von flachdimensionierten Einblockgriindungen im Mastbau (Contribution to the design of flat mono-block foundations for overhead lines). Elektrizitiitswirtschaft 82(1983)2, pp. 105 to 114. 7.27 Biirklin, A.: Berechnung von Mastgri.indungen (Calculation of tower foundations). Beton und Eisen ~:i9(1940), pp. 171 to 181. 7.28 Biirklin, A.: Neues Verfahren zur Berechnung von Blockfundamenten for Frei1eitungen (A new method for calculation of mono-block foundations for overhead power lines). Beton und Eisen 39(1940), pp. 210 to 243. 7.29 Sulzberger, G.: Die Fundamante der Freileitungstragwerke und ihre Berechnung (The foundations for overhead line supports and their calculation). Bull. Schweizerischen Elekrotec:hnischen Vereins 36(1940), pp. 240 to 243. 7.30 Wagner, W.: Statik der Starkstromfreileitungen (Statics of overhead power lines). VWEW-Verlag, Frankfurt, 1959.
7.9 References
407
7.31 Hiitte: Des Ingenieurs Taschenbuch, Band I. 28 (The engineer's hand book, Volume I, 28th edition). Verlag Wilhelm Ernst & Sohn, Berlin, 1955. 7.32 Blum, H.: Wirtschaftliche Dalbenformen und deren Berechnung (Economic design of piers and their calculation). Bautechnik 9(1932)2, pp. 50 to 55.
408
7 Cross-span structures, poles and foundations
8 Contact line designs for special applications 8.1
Introduction
Some railway installations require non-standard parts where the standard overhead contact line designs are not suited and modified ones need to be used. These systems include maintenance installations, loading facilities and crossings of different railway systems. Often, such line sections can only be negotiated with limited speeds. The design and implementation of the overhead contract lines for some historically and technically interesting installations are described in this chapter.
8.2
Maintenance installations
As a rule, the maintenance of electric traction vehicles is carried out at indoor depots. The overhead contact line is extended into the depot and designed so that it may be disconnected on each maintenance track. The dimensions of openings in the depot swivel gates to allow entry of the contact vvire take into account the necessary clearances required between live and earthed components. Covers of synthetic material at these openings are designed to prevent flashovers caused by birds entering the depot. Separn.tors for rolling doors permit closing of rolling doors (Figure 8.1). Depot trn.ck disconnectors are used to switch off and earth owrhead contact lines in depots and maintenance facilities. They are equipped with an earth contact. In the disconnected condition they can be barred and locked. The key, which can only be removed in the disconnected and earthed condition, enables opening of the entrance to the~ work platforms. In the case of installations with more than nm tracks, the overhead cont.a.ct lines of all tracks can be switched off by a master switch arranged outside the building. Figure 8.2 shows a typical example of such an arrangement used in DB's Munich depot. Using local control panels, the disconnect.ors supplying the individual maintenance tracks, can be controlled and their position can be monitored. The earthing of the contact line is carried out by means of a manualh operated earthin9 switch. Its s\\·itching
17
Figure 8.1: ~epara.Lm
ror
rolliuf-!, doors
410
8 Contact)ine designs for special applications ____________________ _
.::.::_::::__
Figure 8.2: Device to disconnect and earth the overhead contact lines in a railway depot
Figure 8.3: Contact line installation over a turntable, DB depot Freilassing (Photo: Nitzinger).
position is also displayed at the local control console. A gate arranged above the control console, equipped with six extractable keys locks, the earthing switch in its closed position and protects maintenance personnel from unauthorized and premature release of the earthing. It is only when all the entitled maintenance personnel put their keys into the gate track that the earthing disconnector can be operated and thus re-energize the overhead contact line. Figure 8.3 shows the equipment of a turntable in front of a circular engine shed in DB's Freilassing depot. The radial arranged contact wires supply the electric locomotives on all running tracks via both pantographs. Turning of the turntable is only permitted when the pantographs are lowered. The return current flows to the main tracks by cable connections. At German railway :CB, turntables are no longer installed. Modern locomotive depots have a rectangular layout and the distribution of the locomotives to the individual maintenance tracks is clone with a travelling platform, the locomotives with their pantographs lowered. The tracks are equipped with conventional overhead contact lines. Specifically designed contact line installations are adopted in plants for· washing and de-icing of electric traction units. To avoid any contact between the water and the live contact line when washing the vehicle roofs, the contact line must be interrupted. In such a section the vehicles an! moved by capstans or vvith the second p,rntograph which is 011 tside the washing area. This is tlw case with th<· high-s1w
8.3 Tunnel seals
Figure 8.4: Untensioned arrangement of an overhead contact line in front of a washing facility (ARA) Munich.
able to clean other high-speed trains like the ICE 2 and ICT the washing facility in the Munich depot has been re-fitted with a capstan in the centre section and an overhead contact rail in the adjacent section. Figure 8.4 shows the transition between the flexible overhead contact line and the rigid section in front of the depot entrance.
8. 3
Tunnel seals
Flood gate doors seal under water tunnel sections against flood waters. They are designed as drop gates which remain functional even in case of power supply failures. The report [8.1] describes two different designs for removing the overhead contact line from the working area of the flood gate doors. In Munich, the commuter rail system passes below the river Isar. In this tunnel the overhead contact line on both sides of the flood gate doors is rigidly terminated and the gaps between the two contact lines are closed by 6 m long conductor rails. The falling gate unlocks the conductor rails at one end using rollers. The conductor rail is released and pivots around a hinge at the far end like a pendulum. The overhead conductor rail then falls out of the clearance gauge of the flood gate door. These contact line sections are arranged iu the starting and braking section of the line and are negotiated at 40 km/h. Despite a stepwise transition in elasticity from the elastic contact line to the rigid conductor rail, the latter shows high wear and has to be replaced regularly. Another design was adopted for the urban mass transit railway which crosses the river Main in Frankfurt. Th(~rc dipping dev1,ces are installed to cut the overhead contact line equipment during the lowering of the flood gate doors after automatic disconnection and earthing of tit<~ COllt.act lines (Figure 8.5). Latching in of the tension wheel arrangements limits the daruage of the overhead contact line to the sections cut. As an additional security 111casure, auxiliary midpoint anchors before and after the Hood gate doors help to kc<'p Lil<' cout.act lines in position. A special device for unloading the ov<~rliead contact lin<' <'ttalJl<'s the installation of replac
8 Contact li1H~d<)Sig11s_for special applications
--112 --------- - - -
Figure 8.5: Overhead contact line with clipping devices at a flood gate door in Frankfurt (Photo: Liebig)
dismantle the contact line between splices during the annual functional checks of the flood gate doors. These installations have worked satisfactorily during train operations at 80 km/h and during the annual checks.
8.4 8.4.1
Separation between electrification systems Introduction
In chapter 1 the various historically evolved railway energy supply systems were described. Their geographical application is shown in Figure 1. l. The far ranging nature of international raihvay traffic means that electric trains must be able to operate beyond the limits of individual supply systems. The first transition sect ion in a mainline railway was established in Modane in France in 1930 [8.2]. The paper [8.3] refers to the type and frequency of traffic and the type of adjacent supply s:s,-stems to be connected as crucial to the design of the electrical instaJlation. The installation described below provides secure electrical separation of the overhead contact lines of the adjacent energy supply systems and the feeding of the traction units operating in both systems.
8.4.2
Syste111 separation sections on open lines
System separatum S!'.r:tums 011 open lines are negotiated b:s,r rn,u,lhplr- syslem traction units. At system separation sections between DC and _.\C syst(\ms, tlw p;-rntographs are changed usually heeans
1
1
1
8.4 Se1i,uati011 l>et.we(\I~electrificat.i(2I_l sy~t.ems
I I I I I I
Neutral zone
(3 kV)
0
Ear1hed zone
(3 kV)
Eartl1ed zone
Neutral zone
;
(25 kV)
(25 kV)
:
0
U> Insulating rod
Auxiliary contact line
; Mid point of ; system separation
O
1 I
U>
I>
Main contact line
Main contact line DC 3 kV AVE
AVE
Figure 8.6: System separation section on the Madrid--Seville line. -------::,---i==::=}
AC 25 kV
-------DC 1,5 kV
.,__..,___,,...,. J
R<1
n
Figure 8. 7: System separation section in the SNCF network.
The AC 25 kV /DC 3 kV separation section of the Madrid-Seville line shmvn in Figure 8.G is negotiated with a lowered pantograph [8.4]. Voltage transformers are arranged at the neutral section of auxiliary contact lines to trigger the s,vitching off of the supplying substation circuit breaker in case of inadvertently raised pantographs. If this device failed, the running of the pantograph into the earth section would result in a shortcircuit and s,vitching off of both adjacent power supply systems through the contact line protection. Section insulators made of synthetic material are used to insulate the different contact wire sections. They are also used for the passage of pantographs in emergency cases up to speeds of 280 km/h. Figure 8. 7 shows a system separation section of the SNCF between AC 25 kV and DC 1,S kV. It is formed by protective sections ,vith earthed parts designed as overhead contact lines equipped with a section insulator. It is designed with a power electronic diode, insulated track sections and an impedance bond for the separation of the return current s~·stems. Iu case of system separations between closely related power suppl~· systems with differing voltage levels, for example DC 1,5 kV to DC 3 k\ or 15 k\. AC lG,7 Hz to 25 kV SO Hz, neither pantograph changes nor dropping a.re required. However, as in cases of phase separation sections, the engine driver must svvitch off the main circuit break
8. Contact line designs for special applications
41--1
~------111--Ir~' Ir- _'..,.:;;-<..--------r:: 1>,'<'T 11 T 11 '<' I I I ~i >:: y
/
II
::- ___ - - 11 >o~~ 1-----il '<' y fllj
>o
1,s.
I I I I I
[®
1;f: ,('( ·
I I J I I : I I I
I I \ I I I I
~
I @@1 @@I ©@I
I --l I
®I
11
f
°
11
T
I
i
If
•
~ r-Y - - - - - - - - II y-<.. 6 jlr--- 7 T 111 -'<' T lr'<--L---r:: I~" I 6 If---[
11
I
I I I
T I
'f
11 @ I @ I @ I ,&,. '<@
17:>.
v.(I
,&,. '<@
X
>-,/'../f, 1
I I 17:>.
W
II
71
I I I I
©I @
I
17:>.
17:>.
W
W
Feeding
- - - . AC
®I -
DC
- - - Section with
switchover
Figure 8.8: Overview of a system change railway station in Russia.
8.4.3
Stations with two power supply systems
Multi-system traction units need a higher investment than single-system traction units. In the case of extended electrified lines on both sides of the system separation border and heavily trafficked systems, a large number of multi-system traction units would be necessary to guarantee the unrestricted operation in both systems. In this case, the use of stations equipped with both adjacent traction supply systems and single system trains is more economic. These system separation stations enable the arrival of trains hauled by traction units with one system and its departure hauled by traction units of the adjacent system from the same track as well as the necessary shunting trips for changing the traction unit. The adopted designs and circuit diagrams for stations provided with two types of traction power supply vary widely, since in most cases stations with existing track layout were equipped. There are stations with longitudinal and transverse separation of the contact line (Figure 8.31) without switching the contact line, as well as stations where the contact lines of several numbers of tracks can be supplied with both energy supply systems. In case of contact lines for one supply system only, the single system traction units negotiate the system separation sections coasting with dropped pantographs. Shunting locomotives with independent drives are used to return them to their home system. If a traction unit driver does not drop the pantograph before the system separation section, running into the earthed section triggers a short-circuit and causes the opening of the circuit breakers in the supplying substation. The number of tracks to be equipped with switchable overhead contact lines depends on the track layout and the operational usage. The section insulators arranged above track insulating sections divide the overhead contact line into individual switching sections that are fed by specific switching posts. In a simplified way, Figures 8.8 and 8.9 show switching diagrams for stations equipped with two power supply systems. When locking in the route for the trains, automatic switching of the power supply system is carried out. Because of thr dependencies of the positions of the points, the disconnectors and the signals, running from one switching section into an adjacent. one is only possible if both are fed by the same power supply system [8.5]. The insulation level of the overhead contact line corresponds to the system with the higher nominal voltage. A protection against stray current corrosion is continuously
8.5 Movable -bridges 415 --"''--------------------------------.::.= I
>=-
----------0----
s1021 j20-:;
-
810~
©S203 - - - D- - - - I
-----.-----~•~•--©---...-...----q>.-_.,. _________ AC ----------L-<(D ! DC _.,
I-
~E4
DD
fi-
u11c15u2 q)
/
T
J
1
_
-1-T kG 2,5
w% wcj~
__ g
/ ~~ 2 ,,---81-8 j' I
I I I I
~S2
+f 1-G1,4-
-
-
-
Earth
oD1-- - -tDD .J9 l QI
+
-
.-
6 W ~ , ~s1 ~E3
-•
0
-
-
-t- - -I -+
0 ~
,~~w± Ag sw
1·-----j-- ...-H-• II
-1-T -I- -I
I I
! l'.
-
-£
- -,
7
-~-t,----1
1
11 o--J
- - - - - - - _j, I I- I - - -I I I 1 2 ~5 L I r- r •- - - - - .7 , - ..._ - ---1 1/( I DC I I I I II I Sections with I I I I_ , I I I
__._I-©:::-../
I
tG~f-/
~£Ycr=11-1-Hr-r-
®1=---------------------------------=-T-17-
switchover
I I
J
Figure 8.9: Overview of a system change railway station Emmerich (Germany /Netherlands).
necessary for all poles at the station. Stations provided for two types of traction power supply systems permit mixed operation ofsingle-system and multi-system traction units. For slow trains, one-system traction units with engine changes are used while rapid trains adopt multi-system traction units. These don't require a time consuming engine change with shunting operations.
8.5 8.5.1
Movable bridges Introduction
A1ovable bridges enable an unhindered crossing of railway lines and shipping lanes without limiting the clearance height for shipping. When equipping these bridges with contact lines, the constraints of both traffic systems must be met. In the Netherlands, some movable parts of bridges were not equipped with contact lines but are operated in a coasting condition with the pantographs dropped. Overhead conductor rails similar to those described in clause 8. 7.3 on both sides of the bridges gradually guide the pantographs to their upper position and push them clown to their normal level aft.er passing the bridge, if the driver has failed to drop the pantograph. During this procedure the pantograph reaches maximum development, but this only exceeds the maximum cont.act wire height by a small amount. Bcca11se of their design, t.ltc pantographs used at DB ;.-u·c able to dl'vdop to 6,85 m ,1ho\"(~ Llw top of rail. If the bridg<'S arc sit.m1,U~d dose to stations or signal positions,
416 - - - - -
8 Contact line (18signsfm _spe<:.ial applications
stopping of coasting trains cannot be excluded. In such cases, a.n uninterrupted current supply to the traction units is necessary. Turning, folding and lifting bridges in Germany were erected many decades ago and many form monuments to the art of engineering. The electrification of such bridges, must be preceded by a thorough check of the bridge's loading capability. Some bridges cannot carry the loads from dead-end poles and from tensile forces of elastic overhead contact lines that would be more favourable in view of current collection. Such bridges are often equipped with overhead conductor rails. Such a design, together with the vibrations of the bridges would limit the running speed. Trains usually coast over these bridges with pantographs dropped. In this case, the overhead contact line serves as an emergency running surface for pantographs unintentionally left in the raised position and as a feeding possibility for starting traction units with pantographs at the contact wire. Paper [8.6] describes installations of overhead conductor rails on movable bridges when electrifying the line New Haven-Boston with AC 25 kV.
8.5.2
Contaf.:t line design
8.5.2.1
Folding bridges
Folding bridges with balance beams offer sufficient space for conductor rails. The transition between those parts of the contact line which are connected to the movable parts of the bridge and the adjacent fixed sections require special consideration and attention. In the case of folding bridges equipped with counter balance m~ights of the Scherzer system, the counter weights move on the opposite side of the pirnt into the gauge of the railway line. For the equipment of such bridges, runners or conductor rail overhead lines are used which are moved out of the operational range of the balance weights before the folding process of the bridge is started. Examples of existing installations are the folding bridges in Germany across the dead-end channel south of Papenburg; across the shipping lane in Emden; both on the line Salzbergen-Emclen-Nordcleich electrified in 1980; across the river Hunte close to the City of Oldenburg on the line BremenOldenburg electrified in 1980; across the river Peene close to the City of Anklam on the line Berlin-Stralsuncl electrified in 1988; across the stream Ziegelgra ben dose to Stralsund on the line Stralsund-Saf3nitz elecctrifiecl in 1989. In case of the Papenlrnrg folding bridge, the balance beam ,,·2ls extended and used as a supporl· for the con cl uctor rails. The counter balance weight of both bridges had to be enlarged corn'spondingl>·· A pair of rurmers simil2tr to those used for section insulators (Figure 8 . 10) prn,·idC's the connection to the elastic couta.ct li11f's ou both banks of the river where the dast ic merhead contact lirws ar<' t<~rminat<'cl. An elastic br,lck<'t nhow th<' rnrn1<·1s ,llld ,,hm·p Ill(' c0tt
8.5 Movabh\ bridges __
Figure 8.10: Folding bridge close to the City of Papenburg.
running level for the pantograph and dampens vibration. The elasticity is gradually reduced towards the bridge by additional contact wire sections clamped to the active one (8.7]. In the case of the folding bridges on the Bremen-Oldenburg line, portals on both sides are used to terminate the contact lines and support the folding parts of the conductor rails. They also support the corresponding drives and operating linkage on the side of the bridge where the balance weights are arranged. The four short overhead contact line sections arranged on the flaps of the bridge form an unusual feature. The contact lines are terminated rigidly at the dead-end portal in the middle of the bridge and flexibly at the weight casings by means of spring-type tensioning devices. The swivelling arms move at tvvo speeds. They start with a higher speed to keep the operation period below 30 seconds and are braked before reaching their end position to reduce momentum [8.8]. The folding bridge across the River Peene dose to Anklam and that across the stream Ziegelgraben dose to Stralsund, are equipped with conductor rail overhead lines on their movable parts and the adjacent bridge sections. Their swivelling cantilewrs are provided with a drive to turn the overhead contact line out of the reach of the balance weight (Figure 8.11) before opening the bridges. In view of the adverse dynamic characteristics of the overhead contact line, which is affected by the vibrations of the bridges and as a result of running tests, the maximum rnnning speed with raised pantograph was limited to 20 km/h for the Ziegelgraben bridge and to 10 km/h for the Peene bridge. However, usually the latter bridge is negotiated with dropped pantographs and the train in coasting condition. Tlw New Haven to Boston line electrified by Amtrak in 1999 crosses the Con11eticut Hivcr, Niantic River and Tha11us River 011 ba.scule bridges which have been equipped ,vith overhead conductor rails (Figure 8.12) designed for 145 km/h maximum speed [8.G]. ·ro enable bridging of the gap lwt,,·e<'ll movable and fixed parts of the bridge a 111malil<' <·011tact li1w unit, is used. [t, co111p1isc\S of a portal strnctme which moves on 1111111i11g 1,1ils 11101111lc•d 011 girdc•ts nrrn11g('d l)('tm·<'ll t.h<' pi11s . Tit<· 1110,;ilil<' contact line
8 Contact line dcsig,Hs for speciala.pplications
-118
Figure 8.11: Folding bridge across the river Peene close to Anklam.
unit is mounted on the portal structure and provided with a mechanism that enables to move the contact line out of the line gauge (Figure 8.12). Interlocks in the control system prevent the bascule span to be opened before the movable contact line unit is fully retratecL
8.5.2.2
Swivelling bridges
Swivelhng bridges rotate by 90° around a vC'rtical pivot supported on a pillar arranged in the middle of the bridge and open shipping lanes on both sides. Laterally latching runners, arranged at the moving part of tl1r bridge, form owrlaps with the counterparts of the overhead contact line arrang('d at 1he adjacent rigid parts of the bridges or on the river banks. The swivelling bridge across the riwr Hunt<~ dose to Elsfleth (Figur0 8.13) is an example of an installation which was electrified at, the time of the Br0.nwn-H11de-Nordenham line electrification in 1980 [8.8]. B<'l'ore starting the swiwlling opc~ration, the locks of the tracks and the bridge are liftr,d h\· 0JG m, the free ends of the bridges being lifted by 0,20 m only. Att,ached to 1hr' swivelling part of the bridge is a 200 mm 2 overhead contact line supported bv a t('ctangula.: hollmY galvanised str!el section. The overhead contact line can a<'.Cornrno
419
Figure 8.12: Bascule bridge with overhead conductor rails from Fmrer Haven-Boston-line.
+
Frey on New
··-
Figure 8.13: Swiv<~lling lnidg<' across Lite river Htu1t.e clos<· tu rl1<' Citv of Elslktli tt1rni11g iu a lifted position
. _ 8 Contact linedesigns for special applications
420
Figure 8.14: Swivelling bridge with rotating overlap with overhead conductor rails from Furrer + Frey on New Haven-Boston-line.
The Amtrak line mentioned in 8.5.2.1 crosses as well Shmv's Cove River and Mystic River on swivelling bridges. The movable parts are equipped with conductor rails. The transition from c:atenary system to the conductor rail is arranged on the fixed bridge heads. Rotating components are arranged to bridge the gap between fixed and movable parts at both ends. These motor-operated components allow for enough space for bridge operation. Inline horns guarantee the mechanical and electrical transition (Figure 8.14) [8.G].
8.5.2.3
Lifting bridges
In the case of a 17,fb,nr; bridqe the mOY<1ble section of tli<' bridge glides wrtically along pillars arranged at both ends. In the opened for the navigation position, the raised section of the bridge limits the clearance of ships, tlw tctllest n:ssels operating on the shipping larn~ and the maximum vvater level determine the requinxl lifting height. The lifting height of bridges varies from a fow meters up to 63 m as in case of the bridge crossing the river Maas in Belgium. The lifting bridge across tb~ I,at,tw.vk waterway within the Hamburg seaport depicted in Figure 8.15 was co111111issioued in 1~)",3 and is used for rail and road traffic in parallel whil(! th<· lift.eel section is IOG Ill long and raised hv aro11nd 4G nL In 108:3. this section of tit<' bridg<' was
8.5 Movable_bridges
421
Figure 8.15: Lifting bridge crossing the Kattwyk waterway within the Hamburg seaport.
Figure 8.16: Movable conductor rails of the Kattwyk lifting bridge showing train operation position (left) and "lifting of the bridge .. '(right).
the structural sted work of che bridge [8.9]. The elastic contc1ct line equipment is terminated on both sides 11 111 before the <'ncl of the rigid parts of th<' bridge and is continued by an 8 m long rigid onirhead conductor raiL This cond 11ctor rnil cuds :3 m before the transition from the fixed parts of the bridge to the mmablc part, since the balance weights of the lifting bridge reach into the cle;-mutn' of r!L<~ railwa, ,rnd road in the raised position of tl1e bridge The remaining gaps are bridg<'d h,· apprnxirnately 8 Ill long movable overhead <·ontact Jin<' sections, \\'hich ar(' ttt
1
1
I
I
8 Contact line designs for special applications
422
Pipe line cable undercrossing Disconnector Supplying conductor 15 kV/ 16,7 Hz
Section insulator -0---C_o_nt_ac_t_w_ire_-oLJ_ Contact line carriage (west side)
l
lifting section
Return conductor Running rail
~t~>--
C7
Pipe line cable undercrossing
Figure 8.17: Schematic connection diagram of the 15 kV AC overhead contact line at the
Kattwyk bridge. contact line on the lifting section. Three meter long conductor rail contact lines serve as transitions to the rigidly terminated contact line equipment on the movable bridge section.
8.5.3
Electrical connections and signalling
Electrical connections and signalling must co-ordinate the moving of the bridge with railway operation and mergining of the contact line. Before opening the movable part of the bridge, the voltage on the contact line is switched off and can only be re-energized after closing and locking the movable parts. Before and after the bridges there are isolation points or protective sections which are earthed after de-energizing the bridge section. The arrangement depicted in Figure 8.17 allows for the necessary switching operations and the continuation of supply to successive feeding sections via by-pass lines. These are often cables installed in the river bed or in pipelines. \Vhen adopting overhead power lines for this purpose the necessary clearance for navigation has to be observed and may reach up to 65 m. When planning the installation. the security of the traction return current via overhead power lines or cable must be considered. To ensure security of the return current during operation of a traction unit on the bridge, the movable parts of the Kattwyk bridge were equipped with contact blades for the return current. These use cables to connect the running rails of the indi\·idual parts of the bridge. \,Vhile in the open condition, a stop signal is displayed to trains approaching movable bridges, so a separate signal for the switching condition of the contact line is not necessary. A special case exists for bridges where pantographs traverse the overhead contact line at low speeds and with dropped pantographs at high speeds. For these situations adequate instructions are given in the service instructions for sections with speed reductions .
Figure 8.18: Level crossing between a mainline railway and a light-rail tramway in Markkleeberg close to Leipzig, Germany.
8. 6
8.6.1
Level crossings of lines fed by differing power supply systems Crossing between mainline railways and tramways
In Germany there are some level crossings between mainline railways and tramways. Examples are the following crossings railway Schalke-\i\Tanne with the tramway Bismarckstral3e in Gelsenkirchen; railway Huckarde Sud branch to Deusen in Dortmund and Dortmund city lightrail system; railway Leipzig to Altenburg and local tramway in lVIarkkleeberg close to Leipzig. Since only pantographs are used for the tn:urnvay vehicle, it was feasible to wire the lines crossing squarely with overhead contact line crossing equipment (Figure 8.18). The contact wire of the mainline railway contact line is arranged underneath the contact wire for the trarnwav system and provides more favomable rnnning conditions for che mainline. Using additional contact wires damped to the contact wires, the difference in !wight bet,veen th(~ crossing contact win'S is reduced and the traniw,-t_v pantogra.ph is g11ided to the level of the lower mciin lillc contact wire. To amid ,inv longitudinal movcrncllt ol tlw contact lines lwcause of L<'tnperntmc clrnng<'s. tll(' crossing is designrd
8 Contact_line designs for special applications
-124 ------------Lightrail tram
Main line railway
-l'"l;
1-+-l~ 1-'_L'
AC 15 kV
TDC 600V
Figure 8.19: Schematic connection diagram of the crossing between mainline railway and light-rail tramway at Markkleeberg close to Leipzig in Germany.
in the same manner as a midspan anchor. The running speeds are limited due to the additional masses in the crossing area and reach 50 km/h for the mainlines and 30 km/h for the tramways. An increase of speed might be achieved by improving the elasticity within the crossing section, for example by the use of springs for the droppers. When designing level crossings between mainline railways and local light-rail systems, the possibility of connecting the mainline system to the power supply of the lightrail system rrrnst be excluded. Consequently, the crossing overhead contact lines are equipped with protective sections or section insulators in all four directions (Figure 8.19). On the Markleeberg system, when the light-rail vehicles are operated, a disconnector feeds the 600 V potential into the common overhead contact line section. The short protection sections of the DB contact line are equipped with a continuously earthed middle section. End position contacts arranged in the barrier beams control the opening of the disconnectors when the barriers are closed. A neutral potential is achieved at the common overhead contact line section when the crossing is open for mainline operation. The traction units of the DB pass through the crossing in a coasting condition with their main circuit breakers open. If a traction unit driver forgets to open the main circuit breaker, arcing will be initiated at the protection section with the short-circuit leading to switching off of the feeding circuit breaker in the substation. The line gradients enable the vehicles to coast out of the crossing section without needing to engage the drive in any case. Using this configuration, there is no hazard to people or equipment. An alternative solution is shown in Figure 8.20 that enables the feeding of AC 15 kV into the insulated sections of the mainline ra.ilways and the central sections. In addition to the usual signalling of the level crossings, the coasting sections of mainline are protected by Ell "main circuit breaker open" signals before the crossing and El2 "main circuit breaker closed" signals after the crossing.
8.6.2
Crossings between light-rail and trolley bus lines
The only known level crossing ;)et;wee11 an electrified mainline railway and a trolley bns line is at Innsbruck [8.2]. So, the following S<'ctio11 will concentrate on the large number of existing crnssings helween light-'lnil s_vst ems mul trolley hns lines. The crossing components are designed taking into rn11sid<,rnt.io11 thC' pa.ntographs or current collectors nsed. The majority of light-mil S\sl.<'.111s 11s<' prn1togrnphs !hat t.011cli tlw contact \Vire
425
a2
--lt-----
15 kV
Train
a3
a1
e-----o---u
1
a4
Figure 8.20: Schematic connection diagram of the crossing between mainline railway and light-rail tram system at Gelsenkirchen in Germany showing the 15 kV operational condition.
Figure 8.21: Gliding shoe of a pole trolley current collector.
from underneath. The pole trolleys of trolley buses however, are equipped with gliding shoes which also embrace the contact wire laterally (Figure 8.21). A simple crossing of the contact wires is therefore excluded since it would lead to dewirement and damage to the collectors. To avoid costly adjustable configurations, the pole trolley gliding shoes should be able to pass under the level of the tramway pantographs without any obstacles. Depending on the angle of the contact ,vire crossing, two configmations are used. For crossings (Figure 8.22) with angles betwren 15° and 75° a crossing filler is us<:cl. Here the light-rail pantograph is guided across the gaps between the trolley bus contact wires by insulated gliding nmners. In the case of perpendicular crossings, often encountered at light-rail and trolley bus crossings within downtown areas of cities tlw gaps are more difficult to negotiat<:. In the configuration shown in Figure 8.2:1 the pantographs of the tramway vehicles pass Llir crossing section utilising tlw width of Ill<~ rnllcctor strips and the inertia of t.lH' pantograplt h<'.acl. Ev
8 Contact line designs for special applications
426
lig)1t-rail line
Figure 8.22: Contact line arrangement for an oblique crossing between a light-rail line and a trolley bus.
trolley bus
Figure 8.23: Contact line arrangement for a perpendicular crossing between a light-rail line and a trolley bus.
to the required insulation clearances, the interruption of the sliding path is so short that the collector strips will not be damaged. Since no switching is carried out with crossings between light-rail systems and trolley bus systems the crossing components have to be insulated with respect to the different potentials of the two trolley bus overhead contact wires considering the profile of the gliding shoes. A crossing planned between a mainline railway and a trolley bus system is described in [8.10].
8. 7 8. 7.1
Contact line design above level crossings Arrangements for standard height transports
Overhead contact lines limit the ma:i:inmm clearance for road traffic at level crossings with raiZwa.y lines. According to the German directive for road traffic [8.11] the height of road vehicles is limited to 4,00 m. Exceeding this \·alue is only permitted in the case of oversize f;ransports which havr. to be advised and approved by the traffic police. German mainline rnilwav s_vst,<'111 levd crossings exist only 011 lirn~s which arr. negotiated at a maximum SJH'l'd of l(iO k111/h. The standards EN ;::i0l:22-1, DI\ \T)E 0115-3 and
8.7 Contact
~11e designabove level crossings
DD's guidelines for overhead contact lines Gbr 997 require a minimum clearance of S,[>0 m between the contad, line or other lines support<'d liv the contact line poles and the road surface at nominal voltages above AC 1 k\. or DC l,S kV. This clearance shall be maintained under the most unfavourable conditions. All thermal effects, movements of the contact wire and other conductors and ice accrPt.ion on the conductors must be considered. The consequences are explained by means of an example. In order not to infringe the minimum clearance of 5,50 m the contact line has to with an increased contact wire height according to the following consideration: -· minimum clearance between overhead contact line and road surface provision for lifting of tracks -- sag at specified ice load - tolerance for erection contact wire movement downwards - sag between two droppers The contact wire height in still air is
CWH
=
be installed 5,50 0,05 0,07 0,03 0,05 0,02
m m m m m rn
5,72 rn
Since for DB lines with running speeds up to 160 km/h the standard contact wire height is only 5,50 m, compliance with the rninirnum clea:rance at level crossings requires increasing the contact wire height. Consequently, above le\·el crossings the contact wire height has to be increased taking into account the requirements on gradients and changing of gradients as described in chapters 2 and 5. When level crossings fall below the minimum contact wire height established above, the crossings have to be safeguarded by the installation of height limiting structv.res for road vehicles. These are accompanied by warning posts with additional signs "Warning against dangerous electrical voltage" and corresponding traffic prohibiting posts according to German directive for road traffic (St VO). Figure 8. 24 shows a height limitation installation with a pro.file gate, the lower edge of which is arranged 0,8 m below the contact wire. The maximum permissible height shown on the traffic post must be at least 0, 1 m less than that of the height limiting installation. Such provisions may be necessary if low bridges cross the railway. For examplr pedestrian bridges, close to the road level crossing reduce the clearance gauge for the overhead contact line.
8. 7 .2
Arrangements for oversize transports with permanently increased contact wire heights
If t.here is no restriction on the contact wire height caus(xl bv other structures, the permissible height for passing road whides can lw incn'ased b, lifting the contact line height where necessary. For example, for regular on~rsize transports with increased heights the 1na:C'i.rn:um. 7;osszble contact wire hcu;ht, at le,el road crossings is approxirnately 6,00 m on the DB rail system. This results from the ma:rinmm. devdo7m1.ent of the pu:ntogro.ph which is 6,[>0 BL According t.o urc leaflet 60? this is reduced bv contact wir<' uplift when pantographs pass by and tit<' additional dfocts consiclcrC'd in the cxa111pk~ above. Deviations from tit(' standard co11tact wit<' h<>igltt rc'.quir<' an inneased <'ffmt for cn~ction and rnaiutcnann'. for exalllpl<' hv tall<'r pol('s. incr<',1:-i<~d <'fforts for ,1dj11st111<'11t. 1111d incn'as<~d W<'at of tlw rnnt:HI wil<' '[ li<·1<·fon·. s11ch d<·\'i:1t.io11:-; should
.. ____ § Cont,~ct. line designs for special applications
-!28
H "·' Clearance of the contact wire from the upper surface of the road
h hF
= Clearance of the height limit from the upper surface or the road permissible height of the road vehicles
H-0,80m h - 0, 10 or H- (0,80 + 0, 10) m, respectively prohibition of vehides more than 4, m high (StVO sketch 265)
7
0::,
0
'
E red-white reflecting guiding plates according to German directive on road traffic (StVO)
0
Figure 8.24: Height restriction arrangement with profile gate according to DB standard 4 Ebs 19.01.01.
only be applied in approved cases. A further increase in the height for passing oversize transports is possible by deenergizing and earthing the contact lines within the line section of the road level crossing. The clearance between the road vehicle and the contact wire may be reduced to a fow centimetres whilst still considering the sway of the vehicles. The tolerable rna.mnv,rn, vehicle height, is nearly 6,00 m under the most favourable conditions. The de-energizing and earthing of the contact line requires specialized railway personnel and corresponding blocking of or breaks in train traffic. This procedure is only applied in the case of rare oversize transports reaching maximum heights.
8.7.3
Arrangement of gaps within the overhead contact line
Interruption of the conlact line above a level crossing is an alternative for enabling over-size transport crossings ·without restrictions 011 height. Before the gap in the wiring pantographs have to be dropped and then the train rnasted through the crossing. The level crossing of IlN 9 dose to Le Havre in Frauce [8.12] is such an example (Figure 8.25) The overl1<\ad coutac:t liu<>s are tenuin,\ted rigidly at gantries 011 both sides of the mad.
K 7 Contact li1w
tl_<:sLgn
above level crossi11µ,s
429
Figure 8.25: Contact line design used at the ovcr-si1/,C vehicle crossing of RN 9 close to Le Havre, France.
If the driver neglects to drop the pantograph before the level crossing, conductor rails will guide the pantographs into their highest position of development and back to the standard operating level aJter passing the gap. From the aspect of efficient electric traction such an installation is undesirable because the pantograph has to be dropped. the main circuit breaker opened and the speed reduced. However, there is the advantage of not limiting the height of over-size transports.
8. 7.4
Temporary lifting of contact line by movable cantilevers
8.7.4.1
General
If a level crossing is often negotiated by oversize transports which require frequent contact wire modification, it rna.y he more economic: to install special arfjustable height des(gns. An important criterion for the application of such special designs to increase the clearance at level crossings is a combination of high frequency and increased height of oversize transports for which other alternatives were uneconomic. The effort expended on such designs will be compensated by avoiding dismantling of the line and the accompanied line blocking for long periods. These special designs can be applied at level crossings of electrified rn.ihva_v lines with international rout.PS for oversi1,e transports, access roads to ports and production plants. At the crossing between national highway B 8 and the Oberhaus<'n-Ermnerich raihvay line at Wesel, Germany, an ov1:rhead contact line l-U'ting installation was installed in the 1960's and 70's. This enabled the regular transportation of bulk, 1w1chiuc parts from a nearby plant to th(' \Vesel River Rhein port [8.13] in G<'nwrny . Fom movable overhead contact line cantilevers on both sides of the double track line section were arranged at the double charrnel poles adjacent to the level crossing. (Figun' 8.26). Installed on guiding channel sections, the cantilevers and the c:o11tad line above the crossing could be raised by 3,00 rn. The operation was carried otl t b~, !Ilea.us of a steel wire rope mechanism driven by electric: motors and c:ontrnllecl frn111 a nearh,· barrier post. In the raised position, no electric: tra.cti<,n mts possible. The installiition was removed after the discontirmation of ov(~rsize transports. The B<'.rli11-St.ralsuud rnilway lirH'. crnsses au i11tcrnatioual r0tll(' for lwan-\\('ight and ov<'rsize vehicle t.rn11sporL1t.io11 <1t Bi<·scnl ha! st.at.ion. \Vll('fl d<·ct rih i11g I lt<' li11<' in 1988 a11d i11 vi<'w of ii propos(·d J()() tu111spo1 t crossings jH'l \<'ill \\ it 11 a lwighl ol 7,00 111
8 Contact line designs for specia.l applications
Figure 8.26: Vertically movable cantilever at a crossing in the vicinity of Wesel, Germany.
~
f~
/tl
Figure 8.27: Cantik~V()ts pivoting in a vertical plane at a level crossing in Biesenthal, Germany
431
Reinforcing feeder line
<;>---<;>--------,--------------------0---0---
G
-,;e 1 '
Reinforcing feeder line
Figure 8.28: Schematic circuit diagram for the station and oversize level crossing at Biesenthal, Germany.
it was decided that as an alternative to the erection of a bridge, a contact line lifting system would be installed and tested [8.14]. A total of six cantileYers are equipped and fixed to the poles by means of parallelogram-type linkages and corresponding supports which enable the cantilevers to pivot in a vertical plane (Figure 8.27). Each of the three parallel contact lines is lifted by a separate steel wire rope mechanism that is electrically driven and controlled synchronously. In case of a failure in the electric drives, crank-operated gears enable manual lifting and lowering of the cantilevers. The raising takes 20 s when carried out electrically and 1 min in case of manual operation for each direction. Therefore, passing of an oversize transport can be carried out during a break between trains. In the lowered position, the overhead contact line permits an unrestricted running speed. There is no signalling of the lifting condition either to the road traffic or to the electric rail operation. Measurements taken during the test period have demonstrated that there are neither additional tensile forces in the contact line elements nor permanent deformations. The almost doubled tensile force at the stitch wires in the raised position requires increased conductor cross-sections. The weights of the tensioning device do not move during the raising process. Guided by the parallelogram linkage, the cantilever provides the advantage of secure return of the overhead contact line to the initial position, even in case of ice accretion on the lines. An isolated power supply circuit (Figure 8.28 enables switching ott· of contact lines at the railway crossing and conducting the power via by-passing reinforcing feeder lines. A similarly designed installation for a double track railway crossing was installed at Jacobsdorf station when electrifying the railway line from Berlin to Frankfurt/O.
8.7.5
Ten1porary lifting or re1noving of the contact lines by n1anual procedures
Ir tlw clearance for passinµ, over-size transports is a rare c, C'.11L onl, 011e of the following 1
al L<)rnati, <)S can lw adopt.<)d ·
-- /tn,zs1,n,11 the rn11.!ad WU!'. /Jy 111,1:11.n:o of 1:r1:r:/:1,on rfru1,11's IJY ,1pp10'\.i1m1,tcly 1.00 m:
.,
I'
8 Contact. J~1~_designs for special applications
-132
If it is already known when designing the contact line that this alternative may be used, then its application can be eased by increasing the system height in the vicinity of the level crossing and by considering the resulting loading when designing the supports. Partial or complete dismantling: For the passage of machines used in open pit mining with heights above 10 m, the contact lines are dismantled and temporarily deposited between the tracks. Both alternatives require extended track occupation, de-energizing and earthing of the contact line as well as an increased commitment of personnel, erection tools and vehicles. Such methods, are only applied in very rare cases with oversize transports heights above 6,00 m, for example when transferring large machinery used in open pit mining.
8.8 8.8.1
Container terminals, loading tracks, railway lines in mines
and
checking
Swiveling contact lines
Container terminals will often not be electrified so that loading operations by portal cranes remain undisturbed. This results in a change of engines after finishing the loading operations and cost-effective availability of extra diesel or hybrid engines. The swivelling of overhead contact line design described below and applied on parts of or the total length of the loading track, permits secure loading and unloading of container trains and the exclusive use of electric traction. Installations as described in [8.15] enable swivelling in vertical planes of all cantilevers of an overhead contact line section around their pivots at the poles. Swivelling upwards as per Figure 8.29 a) or downwards as per Figure 8.29 b) of the cantilevers form viable alternatives. Because of the lateral displacement, the contact line is moved out of the clearance gauge of the track allowing unhindered loading operations. The geometry of the contact line changes during the movement. A separate operating mechanism is required for each pole. According to Figure 8.30 the horizontally svrivelling contact line consists of a trolley wire overhead contact line with bridle wires at swivelling cantilevers [8.16]. The contact line can be negotiated at 75 km/h. The tensioning equipment at one end of the overhead contact line section permits a lateral movement. of the overhead contact line initiated by an operating mPchanism at the other end This movement leads to a horizontal turning of around 85°, and moves the contact. line out of the loading gauge within a period of 2 min. Two-span overlaps accornmo
433 I
I I
a)
0-. '
I
"J'--,, \''
b)
'
\ \
','' h \
'
.,
'\ \
' \1
Figure 8.29: Vertically swivelling cantilevers for container i,tations. a) swivelling upwards, b) swivelling downwards
contact wire could be installed at a height of 6,30 rn allowing for rn,a,;z;zrn:um perrnissible contact wire V,plijt. The containers are then loaded or unloaded by hydraulically operated swivelling arms.
8.8.2
Circuit diagra1ns for loading and checking tracks
Before swivelling the contact line or carrying out loading operations within its reach, the contact line above loadzng (J'f checkinq tracks must be de-energized aud carthecL Frequently required switching and earthing operations, e. g. for overhead coutact line over loading and customs management tracks, can be eased by switching devices and operating equipment similar to those shown iu Figure 8.2. Figme 8.:31
8 Contact line designs for special applications
.
·---·--·---------------------~---~--~---
I Rnnning rails for the crane I Container portal crane
JI ------------------------------Travel track If
Trolley wire contact line flexibly tensioned
JI· Inter-storage area
a)
Flexibly tensioned with electric rope drive
--- ----------------------------------
Twin span overlapping
~-·' !
·----1
j_
60
60
60
60
r:11 1
l=r,
5500
3
2
4
5
n-3
n-2
n-1
n
b)
1!11~~~~~3JJi:::::::· Pulley 181 Bridle wire - - Contact wire 3
4 0 0 0
(0
I ~I QJ §I m
0
II~ 'St
/\
0
t3al I i= I
so
Figure 8.30: Horizontally swivelling overhead contact line for container terminals. a) contact line equipment b) Arrangement relative to the clearance gauge
the push bottom will the contact line be re-energized by the local area train operations manager.
8.8.3
Swivelling stopes and laterally arranged overhead contact lines
Trolley-type overhead contact; l-i:nPs, which are supported by poles mounted directly onto movable tracks of railways iu mines are known as stope-type contact lznes (Figure 8.32). A drmn arranged at the end of the track, called stope end blocking, compensates the required change of l<~ngth in mine ra.ilway service. Before moving the track clee1wrgiiing of the overlwad contact li11<~ is carried out by a circuit breaker and the contact litw is tlwn ea.rth<'d El<~d.ric mine lornmotives are equipped with additional r:urrenl r:nllec/:nn; (Figm<' 8 :H) a1T,\llg<~d lat.<~rnlly. They provide po,v<'r supply within
8.8 gc:ir1t.,~t11~:i terminals, loading_ ai1c(diecking t,rnck?, ~ail way linPs in rni11~_ -----------=4:-=3-=-5
15 kV 16, 7 Hz System separation section 3 kV 606
306
>-----'--------------11-- 2
-~-------------
316
616
Figure 8.31: Schematic diagram for tracks for customs management combined with a system separation section.
r r r ;I;;"""""
rl'~ Figure 8.32: Swivelling stopc supported h poles clamped to the track nf a railway in a rniuc.
Figure 8.33: Laterally arranged current collectm ou a mine loc-ot11otivc ( Photo: Hoffma1tn).
Figure 8.34: Marshalling installations (Photos: Hoffmann), Total view (left), cantilever for laterally arranged trolley wire (right).
the track section, equipped with separate shifting devices for marshalling operations where laterally arranged trolley wire overhead contact lines provide the required space for loading and unloading manoeuvres (Figure 8.34).
8.9
References
8.1 Liebig, A.: Oberleitungen an Wehrkammertoren (Overhead contact lines at flood gate doors). Elektrische Bahnen 95(1997)1/2, pp. 42 to 46. 8 2 ,S,'r:l1wach, G.: Oberleitungen for hochgespannten Einphasenwechselstrom in Deutschland,
Osterreich und der Schweiz (Overhead contact lines for high-voltage single phase currrnt.s in Germany, Austria and Switzerland). Verlag Wet7,el-Druck KG, D-7730 VillingenSchwenningen, 1989.
P.: Teclmische und wirtschaftliche Probleme an den Stof3stellen 7,wischen verse liiedet1<\n Bahnstromsystemen (Technical and economical problems at the transition h<'tw<·<~ll differing traction power supply systc~ms). HIV "Friedrich List" Dresden, 1962 . diss<·1tation thesis.
8 .. \ Kal1ler.
8 . 1 Buw11. E.: Kisf:nrir, H.: Systemtrennstellen auf der Schuellfahrstrecke Madrid-Sevilla
(System sc~p,natioll sections on the high-sp<\ed !in<~ Madrid-Seville). Elektrische Bahnen 1
8. 9 R.eforenn~s
8.5 F'roifo/d, A. W.: Prnjcktirnwa,uic koutaktnoi seti (Planning of overhead contact line insallatious). Verlag Trausport, Moskau 1984. 8.G Co:i:, S. G.; N1i:nl-ist, F.; Mart-i, R.: Deckenstromschieuen fiir Drch- 11nd Klappbriicken (Overhead cowlnctor rnil:-: on moveable bridges.). Elektrische Bahnen 99(2001), pp. 90 to 93. 8. 7 Scl1a.for, H.-D.: Elektrifi½iernug der Streckc SaJ½bergcn--Emden-Norddcich (Mole) (Electrification of the Sal½hcrgc)n· Emden Nonldcich (Mole) line in Germany). Elcktrische Bahncn 78(1980)10, pp. 265 to 269. 8.8 Koswig, .J.; Freidlwfor, H.: Oberleitungsanlagen bei beweglichen Bri.icken im Raum Bremen/Oldenburg (Overhead contact line installations on moveable bridges in the Bremen/Oldenburg area). Elektrische Bahnen 78(1980)10, pp. 278 to 282. 8.9 Hofer, R.: Die Ausriistung Europas gro/3ter Hubbri.icke mit einer 15 kV Oberleitung (Equipment of Europe's largest lifting bridge with an AC 15 kV overhead contact line). Elektrisc:hc Bahuen 85(1987)3, pp. 80 to 85. 8.10 Schmieder, A.: Niveaugleiche Kremmngen elektrifizierter Eisenbahnstrecken mit Obuslinien (Level crossings of electrified railway lines with trolley bus lines). Signal und Schiene, 34(1990)4, pp. 154 to 157. 8.11 Federal Republic of Germany: Directive on road traffic: BGBL Ip. 1565, ber. BGBl. I p. 38, last change 27.12.93, BGBl. I p. 2378. 8.12 N.N.: Dispositifs specianx i11staJles sur le domaine maritime du port du Havre. La vie du rail, 1986, 110. 1129, pp. 3 to 5. 8.13 Mam;, G.: Der elektrische Zugbetrieb der Deutschen Bundesbahn im Jaine 1966 (Electric operation at German Tia.ilway in 1966). Elektrisc:he Bahnen, 38(1967)1, pp. 1 to 15. 8.14 Schmieder, A.: Fa.hrleitungshebeeinric:ht.ung for die Durchfahrt. von Grof.haumtransporten an niveauglcichen Bahniibergiingen (Contact line lifting equipment for the passage of oversi½e tran:-:ports at level railway crossings). Die Stra/3e, 30(1990)6, pp. 20G to 210. 8.15 Patent docnmeutation 180 37 62, Class 20 k. 9/01: Anordnung v011 Faluleitunf!,ell m Verla.dezonen ( Arrn111:',ernc!11t of overhead cont.act lines in loading areas) . 8.16 Scl1111ic/f;, P.: Energievc!1:-:orl:',1mg fiir den elektrischen Zugbetrieb auf Collt,ainerbahnhi:ifen (Power supply for the dectrical railway operation on container terminals). Die Eisenbal111t.echnik, 21 (EJ7:l)"l. pp. 157 to 159.
9 Interaction of pantographs and
o·ver head contact lines 9.1
Introduction
The interaction of the overhead contact wire, with the collectors and the pantograph determines the reliability and quality of the energy supply. This interaction depends on the design of the pantograph and the overhead contact line system and thus depends on a large number of parameters. When train speeds are to be increased high-speed trials have shown the pantograph contact line interaction to be of extreme importance because energy transmission is one factor that limits the maximum speeds achieved [9.1]. Objective criteria, which can be calculated and empirically confirmed by ontrack tests; are required for the evaluation and prediction of contact characteristics. Considerable progress has been made in understanding the theory of contact behaviour and the respective findings have been supplemented by simulation processes and new methods of measurement. Simulation processes, particularly, are useful for developing new systems with increasing performance requirements because the extent to which field tests and trials can be carried out is limited. The system oYerhcad contact line-pantograph is supposed to supply energy to the traction vehicle via continuous electrical and mechanical contact, i. e. without interruptions, whilst simultaneously keeping the wear on the contact wire and the collector strips as low as possible. The energy transmission system, in this case the overhead contact line system especially, as it involves high investments, is expected to achieve a long service life with minimal maintenance requirements. Checking the contact behaviour of existing overhead contact line installations, as a method of assessing and surveying these, is also one way of detecting localized irregularities in order to eliminate them [9.2].
9.2 9.2.1
Technical principles Propagation of transversal impulses along the length of a contact wire under tension
Orn· nit.cria detc~nnining the interaction of pantograph and overhead contact wire, is the way impulses are propagated as wavc\s along tlw lc11gth of the contact wire . A useful 1110dd of the pnH"<~sscs iuvolvc d is achieved liy t1cati11g the contact wire as a tensioned stri11g ,viLhout bc~uding stiffn<'ss. TrcatuwnL of the contact wire as a flexible beam [9.3] is a h11t.lwr irnprnvem<'llt of the methods us<~
-!-10
-------··----~------
~Ji-_1:t~ract,ion of J)cU1t,ogrc1:phs and overhead contact lines
y
.. - -···· Ho I
a
H. --· 0
x
Figure 9.1: Equilibrium of forces acting on a contact wire element
assumed to have a negligible stiffness with a longitudinal stress a and a density 1 (Figure 9.1). When a wire, which is subjected to a longitudinal force H 0 = aA is deflected transversally, each wire element of length dx experiences a restoring force according to the following equation:
= H 0 sin (a+ da)
Fy With a force
rv
tan a=
8y/3x,
H 0 sin a~ H 0 da
(9.1)
we obtain da ~ d:r · (82 y/8.1: 2 ), which results in a restoring
(9.2) The mass of a wire element of length dx is elm = 1 A dx. The equation describing the motion of the element of length dx is transformed to
(9.3) From (9.2) and (9.3), the equation describing the motion of the tensioned contact wire is reduced to
(9.4) This equation is known in conventional mechanics as the wave equation of a taut wire or string. The general solution of this equation is given by all functions haYing the form _IJ
= f (.1:
Cp ·
(9.5)
t)
"·herein
=
Fh = JH /ml 0
(9.6)
1s the wave JJ'l"OJJagatwn speed. For an Cu AC-100 copper wire subject to a force of 10 kN. this value is found to be J10000/0,89 - lOG 1u/s, which is roughly equal to 380 km/h.
----··-··--½l
y X
Running direction
Figure 9.2: Traction vehicle with pantograph movmg along a contact wire
9.2.2
Behaviour of the taut contact wire when subjected to a constant force applied at a point rnoving along it
The objective is to describe the behaviour of the contact wire when a pantograph pressing against it with a consta.nt force F~ travels along it at a speed v (Figure 9.2). For this purpose, differential equation (9.4) can be supplemented to obtain:
32y
. 2 32'.Y
;:) 2 -
cP :=i ?
ut
ux-
F~ .
+ -6 r (;i: -
(9.7)
:i:o)
If the collector strip is located at point :r = 0 at the time t = 0, its location at the time
t is given by the equation :ro - vt In ( 9. 7), the term c5 (:z: - :c 0 ) is a Dzrac delta function with the characteristics c5 (0) 1 and c5(:t f. O) = 0. By applying the given boundary conditions, the delta function can be transformed into a Fourier series: 00
=L
c5 (:x: - :r o)
(\ · si
11 ( 117T i: /
I)
(9.9)
n==1
in which
C 11 = 2/l · sin(mr.i: 0 //)
2// · sin(nJTvt/l)
(9.10)
Bv inserting (9.9) arnl (9.10). (9.7) is tnmsformed to (J'2y :=i :)
' [J2'l)
2F.'
ex:'
ci u:r, + -r,1uL si11(w11.c//) · sin(n7T'ut/l)
-
1
uf-
(9.11)
··)
n== I
As ct solution approach for <·qu;.ll ion (9.11), the equation 'Xi
u(r, l)
L !111(!) - sin(m,.r//) 11
be 11sed. Ir U) l'.2) is iw;<'tl<·d i11tu (D.1 L), we obtain a <'
i1,,(!)
(9.12)
I
+ r·~, (mr/1)~
11 11 ( / )
('> 1/iJ~./) si1t(1rTtl'!//)
S(\<·01td-ordcr littear
diffnential
(9.L3)
9 Interaction ofyantog_E,~P}_is and overl-1._eacl contact lines
442
y
X
P0 =canst
Figure 9.3: Dd.ermining the contact wire uplift
The general solutions for equations of this form are
(9.14) From (9.13) and the above, we obtain
(9.15) The coefficients C 111 and C 211 are deduced from the boundary conditions y 11 (0) - 0 and Yn(0) = 0 as C 111 = 0 and from the equation
Yn (0)
(1 (n1r)2 ( c~ - v2)) (1rnv/l)
= C2n (n1rcr/ l) + 2F~l /
=0
(9.16)
as
C2n
=-
2F,'l 0 2( 2) 1 (mr) c~ - v
V
(9.17)
Cp
With this result, the solution for differential equation (9.11) is found to be:
y(x, t)
2 F~ l
= "-'7f2 (c2 I
p
_
00
) · L_ v2
n- 1
1 . n1r.T ( . n1rvt 2n sm -l- sm - l -
(9.18)
In this solution, we observe the fundamental resonance characteristic that comes into effect when the train's speed v is equal to the wave propagation speed Cr· In this case, the deflection of the contact wire would tend towards infinity. It would then be impossible to draw any current from the wire. The wave propagation speed is a physical limit to energy transmission between overhead contact wire and pantograph. This theoretical deduction has been confirmed in practice during high-speed trials. As the trains approach wave propagation speed, the wire uplift increases to unacceptable values and prevents further speed increases [9A]. The contact wire design and the tension applied to the ccmtact wire must be selected so as to ensure that the difference bet,veen the ma.1:inw,m operating speed and this limit is sufficient to ensure safe contact. Details on this subject are (:xplainecl in section 9.6.2. Practical experience has shown that the wave propagation spc:ecl should be between 1,4 and 1,5 times the train speed.
9.2.3
Contact wire uplift at high speeds
As an initial condition for dd.<'rrnini11g r:ontud 'tmre ·11,71hff; at high ti a.in speeds. reference [9.5] as::mmes that a.t th<' tirn<~ t = 0, cl <·rnwentrnt<'d, constant !'ore<' r~~ is act.inµ, on
443
point :c - 0 of a stationary contact wire (Figure 9.3). By multiplying equation (9.4) by the contact ,virc cross-section and adding the term q(.r, t), it is transformed to (9.19)
in which q(:r, t) is a time-variable linear load. The concentrated force F~ can be formally expressed as a linear load by the expression (9.20)
Here again, c5(:r) is the Dirac delta function and v,(t) is a step function of the type
v,(t < 0) = 0 ; ·u(0) = 0,5 ; '/1,(t > 0)
=
Since q(:r:, t)
0 for
:r-/- 0,
1
(9.21)
equation (9.19) will result in
a2v I at2 = cia2v I a:x:2
(9.22)
If we integrate equation (9.19) over x over any small int.en-al of
<
:S
and also take into consideration equation (9.20) as well as the fact that 8 y/8t must be a continuous function, we obtain -E 2
:r:
E,
2
2
H0
·
[
y
/(
E,
)
I(
t - y -E, t
)
l + 2 mew· / E 8 Yot(0 f;) = F0/ · ·u (t) 2 1
(9.23)
Due to the symmetry at the point, where the force acts, y'(E, t) must be equal to -y'( t). For the boundary condition E-+ 0, (9.23) is transformed to
y'(O, t)
-F~/(2H0 ) • 'u(t)
(9.24)
In the region :r > 0, only one wave y(:r:, t)
;lj(O, t) = -cry'(0, t)
= f 1 (:z:
cpF~/(2 H 0 ) · u(t)
cpt) can occur, and for this reason
F~/(2 nicp)·u(t)
(9.25)
By integration, this results in
y(0, t)
= F~cpt/(2 H 0 ) = ,{0 (-cp · t)
The solutions of this equation for
:i: -/-
(9.26)
O are
y(:1:, t) = 0 y ( :r, t) - F~ ( c:P I -
y(i:, t)
J~(cpt
:1:) / (2 H O)
+ ;1:)/(2 H0 )
(9.27) for --
Cpl
:S
:r
< 0.
Tlwrdon•, at any time/ > 0, tl1cre arc 111inor-sv111111<·tric:al, straiglit-liue wave fronts of grn.dic11ts FU(2110 ) awl +F;;/(2 H0 ) 011 tli(' 1 iglit-lwud and 011 tli<' left-hand side of
9 lul.<\ractiou of pant.og,r,ipl!s a!_1~!__~<>.!}1ead contact lines
444
the point at which th<\ force acts respc('.tiv<\ly. Starting at ti1m\ t at ,vhich th<\ fore<\ acts will lw lifted with a siwcd of'
0, the point
:i:
=0
(9.28) This lifting speed can be considen~cl as a signal that is g<\ncrated by the concentrated force Ft and moves along the contact wire with a propagation Ydocity Cp- At a point in a distance \:r\ from the point at which the fon·<~ is applied, the lifting motion will start at a time \:i:\/ Cp- At any time t > 0, a (·011tac:t wire s
q(:r, t) = F~(t;)o(:r) · ·u(t)
(9.29)
Instead of (9.26), the corresponding solution here is t
y(O, t)
j F~(r)dr
= cp/(2 Ho)·
(9.30)
0
and instead of (9.27), we obtain
t-Ja:/cJ y (:r, t)
cp / (2 H O)
·
/
F~ (T) dT
0
y(x, t) = 0
(9.31)
and thus
(9.32) The deflection of the point of force application, .r = 0, of a contact wire that is stationary at the beginning, is proportional to the total impulse transmitted up to time 1:. The defiertion .speed y(O, t) is proportional to the for<'.C currently acting on the wire. Some studies are ba.sccl on the erroneous assumption that the uplift or deflection is proportional to the contact force. Especially where high S[WPds arc concerned, this assumption leads to wrong conclusions (for more d<~tails, c.L [0.G]). It must also lw stated that the bend angle of th<' <·ont,act. win· is (\Xcv-t ly th<' san1e a.s would be ca.us<~d by a force~; c1.cting on tlw C<~ntr<• of th<~ contact wire m1c-horcd a.t. both ends . .md subject to a. constant tensile force under ('C[ltilihrium conditions Tlw r<\cH·ti\ e force is the sum of tl1<\ vertical <·omponents of th<' t<~11sil<> forC'<'S acting on this point.
9 . 2 Tcdmical p_rinciples _
445
y V
Running direction -
Figure 9.4: Hdkctiou of au impuh-;<) by a. co11ccutrated mass
9.2.4
How a concentrated mass reflects transversal i1npulses travelling along a contact wire
An impulse moving along a contact wire may be blocked, i. e. stopped, at a point .1: 0 in that the motion at this point is pre,ented or compensated by a force acting at this point. The motion at the point :i: 0 to be compensated can be termed y0 (t). It is described by (9.33)
if the wave coming from the left at this point is fi (:r 0 - cpt) and that coming from the right is h(:r: 0 + er/) [9.5]. /\crnrding to equation (9.25), a concentrated readi'lJC force
(9.34) ,vn 11 lcl' "v~
]--,. ,,,. U\., 1'l""clcrl ,,,__,' u d,l,
1·n "''""'"" --~r-· 1··1 1 th ;(' •,0·1·1t· u('"" ulii.:) j.1 ' 1 '• 11 ,it,, '·l,11\., 1.1,llcLil!t:l,el i C\\'
1 •. ·,··1·t·~::,cl '·"l'LS' ,L.Hl:'. " Ii ''l''"" ' ,_ '' lll ' 1·1·t'' 1eu c,,,,, !)cl
length of the contact wire ..\ corresponding reacti,e force would be exerted because of the elastic reaction at any point where the ·wire is damped. As a result of this reactive force, IW\Y reflected waves moving in the opposite direction to the original waves are generated. In mathematical terms. the reflection of wm·es in the contact wire is treated by applying the boundar>· condition y(1: 0. t) - 0 to equation (9.19), which leads to d 'Alernbert 's principle of the reflection of ,va,es by a fixed point. The method described above leads to thP iclC'ntical solution with the additional ad van tag<' that it can be applied relatively easily and more generally to any forms of reffoction. e. g. at points of concentrated masses, springs or droppers. The example below clen1onstratcs this by using a reflecting conccntrnted mass point. Assume that a conc:e11.trn.ted m.u..ss 11! is fixed rigidh· to the contact \Yirc at a point 1: - :z: 0 (Figure 9.4). As a rpsult of the wa,·e coming from the left, y 0 (t) - f(:r 0 cpi:), a reactive force F/(t). the n1ag11it ude of which is not .n·t kncmn. will act 011 th<' rn11tact wire and, in the opposit<' direction. on thC' mass. According to f'quation (~L:2S) the contact wire at point 1 .1· 0 will ,1d1iev<~ th<' speed
(SL35) l)('rn11se of the ct<:·tion of this lure<'. This motion \\·ill li<' sup<'ri111pos<'d 011 t ]!(' 111ot.io11 of !.11is point lwurnse of tit<' i11< otllillg wave~ Th<' total sp<'<'d of this poi11( \\'ill ( lwrd"ore !)(' <'([1lcll t 0
,;(!)
(0.36)
9 Interact.i()Il ()L1>aut(>f,raphs and overhead contact lines
446
This contact wire movement y( f;) at the point :i; - :r: 0 is of course identical to that of the point mass ]YI. It is desc:rib<~d by tlw differential <~quation
JYI jj - -F: (t;)
(9.37)
By eliminating the reaction force\ Fi' (t) from the two differential equations (9.36) and (9.37), the equation is obtained which ckscribes the motion of the point x 0 :
(9.38) which can be integrated immediately since the incoming wave y0 (t;) is known. By means of the overall motion y(t) of the point mass, which is now known, equation (9.36) can be used to calculate the reactive force
F:(t) = 2m~wcr (y(t) - iJo(t)) and therefore the additional speed component also
Yr(t)
= F:(t)/(2m~wcp) = :i;
Yo
and additional motion component
Yr(t)
= y(t)
- Yo(t)
This additional motion y1 (t) is imparted to the left-hand section (i.e. for .T < :r 0 ) of the contact wire in the form of a re.fiected wave y1 [t + (x - x 0 )/crl· The wave transmitted to the contact wire section to the right of the point mass, i.e. 1; 2: x 0 , is:
Yt [t
(x - xo)/cµ]
Yo [t
For an incoming sine wave y 0 (t)
y(t) = Yo(l
19j w)/(1
(.T - xo)/cr]
+ Yr [t - (x
1:0)/cr]
(9.39)
= y0 e)wt, the specific solution of (9.38) is
+ 19 2 w2 ) · eiwt
(9.40)
with
19 = IVI / (2 m~wcp)
(9.41)
The additional motion Yr (t) is thus calculated as
Yr(t)
= y(t)
- Yo(t)
= -:9019w(.i + ·t9w)/(l + ·1J2cJJ 2) · ejwt = :Oreiwl
(9.42)
and from this equation, the reaction force
F;(t)
=
2m~wcp.l/r(t) = -y 0 2j m~wcp·t9w 2 (j f;ofdw 2 (1 - j 19w)/ (1
+ ·l'.J 2 w2 )
·
eiwt
+ ·19cJJ)/ ( 1 + 19 2 w2 )
·
eiwt
(9.43)
can be calculated. The n,,Jfrct;-ion coe.ffit'ienf; is
r
= :9r/'Do
- -'l9uJ(.j
+ ,~w)/(1 + '!9°2w 2 )
(9.4'1)
From (9.43) it can be clc!dnce~d that tlH) amplitude of the :eaction force F/(t) will be ,00 1'vl w 2 at low frequencic~s. At higher frequencies, this amplitude will l,e~ !Jo M w jl) = 2 ,00 ·,n~;wcpw, and therefrn<~ proportional to cu. In this situation, the rdi
9.2 ~echnical principles
447
t
a)
t7
r =0.4, Y = 1,5
_ _ _ _ _ _---1'.c...::<=2::::::::::J=:::::::=:~;:;;:.__!:!_D_ _ _ _ _~ . ~
catenary wire
ty
------ dropper
contact wire dropper
F
T
_j_
-
-
Figure 9.5: Reflection of a wave front by a dropper. (G BA: primary wave, NA: transmitted wave, EF and EA: secondary waves, NZ: dropper) a) Condition shortly before the wave meets the dropper b) Condition shortly after the full wave has passed the dropper
A
E
~,_ ____,_ X
Running direction
9.2.5
How a dropper reflects transversal impulses travelling along a contact wire
In a catenary overhead contact line installation, the contact wire and the messenger ·wire are connected to each other by dropper wires which will reflect transversal impulses. The contact wire is subject to a tensile force Hew and the messenger wire is subject to a tensile force HCA. The masses per unit length are m'cw and m'cA respectively. The mass of the dropper is Jill. The wa.ve in the contact wire, y 0 (t x/ccw ), reaches this dropper, which is at position :r - 0, from the left-hand side (Figure 9.5) and will tend to impart a motion y0 (t) to the dropper. The droppers react to this wave by <.:arrying out a motion y(t), the catenary wire ,vhich is considered to be stationary, exerts a reaction force -2mcACCAY and the contact wire exerts the reaction force F~;w = -2m'cwccw(f;-:i;o)In addition, an inertia reaction force - l\lf:ij will occur. The equation of motion of the dropper is therefore [9.5]
F+
I 2 (rncA ccA
+ rncwccw I
)
Y• +
; Y = ?~ mcwccwYo
]\f '.
I
J
·
(9.45)
J
where ccA HcA/rn'ci\ and ccw Hew /m'cw are the wave propagation speeds along the messenger wire and the contact wire respectively. This (~quation is the same type as (9.38). For an incorniug sine wave y 0 (t;) - Do· eiwt, the specific solution is obtained
y(t) - 2 m~;wCcw / [2 (m.~;wccw
+ ·m~:A ccA) + Alj w] ·Do· eiwt
(9. 16) 0
vVith this, the 1·eflectcd wave along the contact wire can b(\ clcscrilwd as follows
.IJ,(/)
:v(i)
Yo(t)
- (2
111.~;J\ ccJ\
+ Mj w) / (9A7)
-!--18 - - ~
9 luL(ffactiouofpantogrnphs and overhead con!,act lines
Since the mass of the dropper and that of the clips at both ends is low, it is possible to ignore Jilj w i11 equation (9.4G) for frequencies which are not too low. \Vorking on this assumption, trH\ rr:fletlwn coe.ffic'ient ·r for the rdfoction of contact wire waves by a mass-free dropper is:
- (y,/uo)
r = rn~:/\(:cA/('ln~:/\cc:A
+ 111~:wccw)
JHcAmc:A / ( JHc:J\rn'c:A + JHcw·m~;w) .
(9.48)
if the sign which expresses the phase reversal is eliminated. Usually, a dropper is made of thin, highly-flexible wire that is subjected to a load equal to half the weight of the adjacent contact wire segments. If the dropper is lifted by a wave moving along a contact wire, this tensile force is reduced by m~A CcAY m~wccw (:i; - i;0 ). The dropper will become slack when the resulting tensile force is negative. If the distance between droppers is l. the initial tensile force on the dropper is 1n~wg · l and the dropper will become slack when
(9.49)
In conjunction with (9.45), the assumption J"\I slacking of the dropper is found to be
=
0 and (9.48), the condition for the
(9.50) The lower the reflection factor, the tendency oft he droppers to go slack clue to a contact ,vire wave is lower. The refiection factor or coefficient is a characteristic quality of an overhead contact line. For a DB standard overhead contact installation of type Re 160 with an Cu AC100 contact wire and type Bz 50 catenary wire. both subject to a tension of 10 kN, the reflection factor is found to be r = 0,41 [9.6]; for a standard design Re 330 [9. 7] with an Cu:\!Ig AC-120 contact wire at a tension of 27 k\" ,rnd a catenary wire Bz 120 tensioned at :21 kN, the value is r 0,47. The reflection factor is lower when thc catenary wire's mass a,ncl tensile force are lower in relation to the cemtact wire's mass and tensile force. Figure 9.G shows a schematic representation of how a wave is reflected by a dropper \'Z. in this case a straight-line wave front G .-\ generated in the contact wire by a rectangular impulse F' · .6J, for a factor r - 0.-L as well ctS the transmission of this \\·ave in the~ contact win) and the catenary \\·ire The uplift y(t) of the dropper NZ generates t.he wave front NA iu the eontact \\·in' se•ct.ion to the right of thc dropper (in the transmission region). In the catA~mu-~1 wire it ge'll('rntcs the wave front ZD. travelling to the right The \\'ct\e front ZC, ,vhid1 is s,·u1111<·t rind to ZD, rnoves to th() left. The reflected wave EF in t lie• contact wire will lie• s11perirnposc\d on tlw incoming wave front GA, leading Lo ste~cper contact wire slope• S('C't ion BN . TliP wave front \LA can be considered as a superp(Jsition of tl1e p1i11mn ,rnn• f'rn11L L3A a11d tltc wave• front EA. which is symmetrical \() l he· \\,1,·e~ front El·'
9.2 Technical principles
9.2.6
449
Doppler factor
Reflec/;ions of tran.':lvcrsal wave:-; by stationary passive masses or other non-homogeneous sections of the contact line equipHwnt do not lead to au increase in the amplitudes. However, amplitndc increases c:;-1.11 O(Tllr at a pantograph moYing tovvarcls the transversal waves which have been reflected by a dropper or a ste,uh arm [9.8, IJ.9]. The pantograph moves along the contact, wire at a speed v. Let us assurnr\ that tlw contact force acting between the coll(\C'tor and the contact wire is increas<\d by .6,.F(i due to son1e disturbance, e.g. due to an impulse ou the wire. The effect of this contact force increase is superimposed linearly on the other contact win\ and pantograph motion components. According to equation (9.28), the speed of the resulting motion is
(9.Sl)
!io - !::,F~/2 rn~w · ccw
This genera.tes a wave front moving in the direction of the pantograph travel. Due to the Doppler e.fj'ect of a moving source, the gradient of this ,,·aw front is
Yb = !io/ (ccw -
(9.52)
v)
This wave front is reflected with a factor r < l by the next dropper and then moves towards the pantograph with a gradient of
(9.53) and forces the collector to move vertically at a speed of
!i1 =
y: · (Ccvv + v) = :/Jo · r · (Cc\V + v) /
(ccw - v)
(9.54)
since the wave meets a moving receiver object. The factor kcw + u) describes the motion of the receiver objecl. According to equation (9.28), the inertia of the collector causes a sudden steep increase of the contact force by 71
;\} -1
I --
? ~ ·1·1·' ''CW .
c·· C\V . .·11:, I -- -·'F.' l O . ·1·/c··•
(9.SS)
whereby o - (ccw
u) / (ccw
+ 1·)
(9 ::iG)
is the DopplP:r factor for the iutewctiou of the overhead coutact line and pantograph. The pnntograph of mass Jls is suhj<'ctecl subsequently to au impuls<) of
1Hs:IJ1
= AIs ~F( / (2 111cw< cw)
- 11/s · !::,F~; · (r/ n) / (2 111 C\\ r·c\\')
I (9• . •)r ,_,)
fron1 which it can he dedtH'<'d
!::,F'I
(r/n) · ~1~;
(9.G8)
If r/n > 1, th(' contact foll'<~ i11cr<'i\S(' !::,F[ is great<\!" than tlH' migi11,d inc1<'i1S<' ~Fr_\. Fig me rJ.G shows th(' r<'stdl of sllcli ,rn C'ff<'ct for a simple uts<· 11,1111('!, " t <'nsioned crntlcH·t wire origi11allr st ,\t ioll,ll\ ,It t i1tt<) () ,\IHI liavi11µ, a disco11tin11it, i\t 1]1<' point :r,.
9 Interaction of pantographs and overhead contact lines
-150
F'
F
r/a< 1,0
C.
XO I I I I I I I
r/a =
~i:o Hr l : : :i
1,0
...___
__,
11 f---,------,--,----,----,---------,--,---,--,--.,-------,+-,:.11
1,0m :
1
0
/Cr
4,0
I I I I I I I I
r/a >
2,0 1,0
3,0
20 ·
1,0
1,0 Xr
Distance -
0
Figure 9.6: Contact force F' of a mass of 1kg that is pressed against the contact wire with a force of F6 and moves towards a dropper at a speed v = 160 km/h. The wave propagation speed is 106 m/s
For mechanical waves, 'the reftection factor of this discontinuity is r. A pantograph of mass lvfs is assumed to be moving towards the discontinuity at a speed v, keeping in contact with the contact wire, but not exerting any force upon it. A force F~ suddenly occurs after point x 0 has been passed. From x 0 onwards, it will uplift the contact wire. The upward motion of the contact wire precedes the pantograph at the wave propagation speed ccw and is reflected by the discontinuity. The reflected wave front travels towards the pantograph and is reflected by this, whereby additional energy is imparted to the wire due to the pantograph's motion. This procedure is repeated over and over until the pantograph reaches point :rr· In Figure 9.6, it can be seen that each consecutive force increase will be greater than the initial one if r / a > l. The amplitudes of the system will increase until point Xr is reached. If, r / a < 1, the contact force variations will decay. The ratio r / o: is called the ampl~fication coefficient
,v = r/a
(9.59)
,v
As the Doppler factor a is a function of the train speed v, the condition 1 defines the limiting speed v 0 , below which the consecutive force amplitudes are not amplified: v °'
= Ccw (1
r) / (1 + r)
(9.60)
The speed so defined is always lower than the wave propagation speed cc:w along the contact wire. The reftect'ion coeffr:cient r is deduced from equation (9.48) to be: r
1 / ( 1 + /(Hc:wm,~:w) / (HcAn1,'cA))
(9.61)
Example: If the characteristic values of a DD standard catenary system Re 250 [9.10] are inserted in equation (9.60), the result obtained with Hew = HcA = 15 kN: rn'cw = 1,08 kg/m; me::\ 0,59 kg/n1; ccw 422 km/h and r = 0,425 is Vn (Re 250) = 170 km/h. This value is far lower than tlte
{
9.2 Technical pri1_1_ci~les
9.2.7
1
Natural frequencies of an overhead contact line
An overhead contact line is a mechanical system which can oscillate with a large number of degrees of freedom and has nurnerous natural frequencies. Figures 9.15 and 9. lG show the spectra of an overhead contact line. According to [9.S], an overhead contact line suspended between equally spaced poles will exhibit sym,1netrical and anti-s:vmmetrical oscillation modes. In the former, two point·, spaced symnwtrically rdative to a reference point will oscillate in phase. In the latter case, they will oscillat(\ at opposite phases. In the symmetrical mode, there will be an oscillation peak (ant in ode) at the axis of symmetry (i.e. the reference point) and in the anti-symmetrical rnode, there will be an oscillation node. In an overhead contact line comprising an even number of pole intervals, the axis of symmetry is at the support point. With anti-syrnrnetrical oscillations, the wavelength of the basic natural frequency is equal to twice the mast spacing. If we assume the oscillation to be a stationary wave, the frequency can be calculated as
v
Hz
l m
I
Hcw,cA
rncw,cA
N
kg/m
(9.G2)
where c is the mean wave propagation speed along the overhead contact line. With symmetrical oscillations, the section up to the first field dropper is also taken into account. This means that the frequency is given by the equation:
l/2 --: c/(2 l + l1) = J(Hcw + HcA)
I
(mew + mc;A) / (2 l + li)
(9.63)
in which l 1 is the distance between the two droppers nearest to the support. In this simplified model, the frequency of the first harmonic is double the natural frequency. For all other frequencies, it will be necessary to take into account the respective oscillation modes (c.f. [9.11]). For an overhead contact line of standard design Re 250 with l = 65 m and / 1 10 m, the natural frequencies are found to be v 1 = 1,02 Hz and 1/2 = 0,96 Hz, as can also be seen in Figure 9.15.
9.2.8
Dynamic characteristics of typical overhead contact line designs
Table 9.1 shows the dynamic characteristics of the DB standard overhead contact line designs Re 160, Re 250 and Re 330. The wave propagatwn speeds are between 382 km/h and 572 km/h. They are the main component determining the Doppler factor, which is 0,41 for Re 160 at lG0 km/h and 0,2G for Re 250 at 250 km/h. Overhead contact lines havi11g the same dynamic characteristics as tlw Re 1GO design ca11 also lie op('rated at higher speeds, which is the case for the He 200 standard design. The' r<'flcction cocffici<~t1Ls of all three designs are almost <)quaL It is uot possibl(' to choos(\ the caL
9 fotnra.c(;ioll of [lillltographs and 0\f(:r!~~~~~~mtact lines
-152
Table 9.1: Dyna.mi<: d1a.rad,<\ristics of DB stall(hnl ov<:rlH:ad contact line installations [9.G, !).9, 9.10] lJHits
Cont act, line desig11
Rel60
He250
Re 330
Cu AC-100 10
C11A1--', AC-120 15
Cui\lg AC-120 27
Bz; 50
13z; 70
kN
10
E,
Bz 120 21
km/h
382 20 0,413 0,41 (160 km/h) 1,01 0,74/0,76
427 10 0,425 0,26 (250 km/h) 1,63 0,96/1,02
572 8 0,465 0,27 (3,30 km/h) 1,72 1.06/1,15
Contact wirn te11silc for cc
kN
Catena.ry wire tensile fore<: vV,ffe prnpagatio11 speed Non-u11ifo1mity Reflection coefficient Doppler factor
% 1 1
Amplification factor Natural frequencies
1 Hz
0,75 ~ - - - - - - - - - ~ - ~ - - - ~ ~ - - - ~ 7,5 Re 16
-,
I I
l
/'----Re 250
/
'----Re 330
/ R 250 V /
/ (1 88)"'1
/
/
050
100
200
300
Running speed
400
v--
500
km/h
600
Figure 9. 7: Doppler factor a and amplification fac-
tor ,v
The Doppler factor· and the ampl,Uication coe.ffi,ctcnt are functions of the train speed 8s shown in Figure 9. 7. The amplification coefficient tends tm,·Mcls infinity asymptotically as the speed approaches the wave propagatwn speed. Because of this, it is not possible to operat<~ trains at speeds near to the wave propagation speed. Experience in practic8l applications has shown that it is possible to operctte on)rbrctcl contact lines at amplifiC8tion factors of up to 2,5. In the course of test rnns for experimental purposes, it has also been observed that <~nergy transmission is still possible at amplification factors of np to 5,0 (cf clause 9 5.2.2).
I I
9.3 Simulation of interaction of overhead coutact. line:-; aud pautograpli:o .
9.3 9.3.1
453
Simulation of interaction of overhead contact lines and pantographs Purpose and objectives
Use of empirical methods in the dev<~loprnent of new on~rl1ead rnutact li1w designs, which were common in the early period of electrical traction systems, is uo longer feasible for systems intended to supply high-speed vehicles. The practical experience required for further empirical devdopmr.nts is not available for the effects occurring at such speeds. At the same time, the interaction of contact line\ systems and pantographs becomes more pronounced with increasing speeds, so that a useful design strategy can only be achieved using various models of the overall system comprising the two components, overhead contact line and pantograph assembly. Computer sim:ulation 'models are an obvious choice for modelling the interaction of these components. Such mathematical models can be used to illustrate the effects of parameter variations and to evaluate the interaction of different subsystems. The objective of dynamic simulations is to determine the time-related behaviour of the moving contact force e:rerted by the collector strips on the contact wire and of the associated lifting of the contact wire. In this process, it must be possible to analyse the interaction of multiple contact points simultaneously, e.g. when studying the use of individually sprung collector strips or multiple pantographs. To enable validation of the models used, it must also be possible to calculate other characteristics that are easier to measure than the contact force, e.g. the motion of the contact line system [9 .12]. To adequately take into consideration all relevant characteristics, a model must be able to simulate the following characteristics of the overhead contact line equipment: all types of contact wires, catenary wires, stitch wires and droppers, including their material characteristics and installation conditions, different overhead contact line equipment, e.g. stitched catenaries, with a'UJ'l1iary catenary wires 01 with uneven dropper spacing , the dynamic characteristics of all supports, i.e. of the steady arms, cantilen:r supports and masts, discontinuities such as section insulators, overlapping sections, reduction of contact line height and contact line installation above points and complete tensioning lengths. The pantograph and collector model must take into consideration the following ess<'ntial parameters: different types of pantoqrnph ·m,rx:ha:nisrns and their respective cl1aract<'ristics. e.g. single-arm pantograpl1s. twi11-arrn pantographs, and different types of contact d('lll('llts, c. g. pau heads, individual rnllcct<>r s( rips. The parameters of suhs,vst<~1t1s should be casv to change 1wrn1it ti Ilg the optimization of parameters. Fmthennor<'. the qu,ditv of tlw rnodds of th<' pantograph and of the <·11d<'11t s, s(c'111s, ,tpcdi!('
9}nteractiou ofpantographs and overhead contact lines
-154
Ff
m 1 = 10,5 kg
< ?
m 2 = 8,53 kg
I m 3 = 10,57 kg
t %/
Figure 9.8: Three-mass-model of a pantograph type SBS81. m = partial masses; c = modulus of elasticity of the springs; d = damping; FR = friction force
%
1///%
/
Figure 9.9: Six-mass-model of pantographs with individually sprung collector strips (Symbols as in Figure 9.8)
of oscillating and coupled to each other at the point of contact. Pantographs having multiple collector strips will have multiple points of contact short distances apart. The simulation is used to establish the coupling between the partial models via the contact force and the position of the contact point.
9.3.2
Model of the pantograph system
The pantograph point of contact with the overhead contact line forms the coupling point between the two systems. A suitable simulation of the beha\·iour and interaction at this point is required. The contact force and the vertical motion of the contact point must be calculated. If a plane model of the system is used, the force is considered to always act on the same point of the collector strip. The spatial effect of lateral contact wire shift can be taken into consideration by assuming a linear lateral shift of the point at which the force is applied to the collector strip. A simple model involves repn!sentation of the pantograph by s-ubstztute ·musses which are coupled to one another through springs and danqwrs . The oscillation beha\·iom of such systems is descrilwd hv a s_vst<~m of second-order differenti,'ll equations. The number of equations is detcnnined h:v tlw number of sul>stit11te masses. i.e. by the number of degrees of fn:edom of t ll(' sYsL<'lll. i\lodPls with three substitute ltlasses are usually used. They perntit tit<' us<' of rn,1ss<'s tu n'[Jt"(~S<'rrt tli<~ l()\n~r lnune. th<~ upper
455
Y=
(i:)
'!'
Figure 9.10: Analytical pantograph model
frame and the collector-strip pan. Figure 9.8 shows the data of a DB pantograph type SBS 81 as represented in a three-mass model [9.13]. The relatively small number of substitute masses means that only selected pantograph oscillation modes will be taken into consideration. For instance, the flexural oscillations of the upper frame members are not covered by this type of model, nor does a model such as the one shown in Figure 9.8 take into account individually sprung collector strips. A six-mass-model of the type shown in Figure 9.9 is used to study pantographs with individually sprung collector strips. Here the masses of the collector strips are depicted as separate part-masses located on the respective supports. The excitation force along the collector strips is subdivided linearly among the two respective part-masses corresponding to the position of the contact point. In reference [9.14], an analytical model was developed for single-arm pantographs with pan-mounted collector strips. This pantograph model, which has four degrees of freedom (Figure 9 .10) not only takes the vertical motion of the pan springs and the angular motion of the middle and lower joints into consideration but also the bending of the upper frame section. The parameters inserted in the mathematical model are derived from the geometry and material data of tl1e pantograph components. Unfortunately, none of the analytical models are applicable universally, as every small change in the design, e.g. introduction of individually sprung collector strips, ·will require new calcula.tion algorithms. Models of any desired accuracy can be obtained by applying .finite element rnocielling. In reference [9.15], calculations have been presented where the pantograph of the ICE was modelled using finite element methods with 480 degrees of freedom. The calculation effort required for such solutions is high and there is very little improvement. in the precision of the model. For this reason, the authors of the paper [9.15] only used a simple three-mass model to optimize the pantograph design It is also possible to model pantographs using measured, frequency-dependent dvnamic apparent masses and dynamic dast.icity (Figure fU l, from ref [9.1]). In this case, th(, excitation and the response of the pantograph are taken into consideration in the cakulation as superimposed individual resprnis<'s at the ohs<~rn~d frequencies. In !his 111odd, the use of freq11e11n·-d(•pe1}(l<'nt ca!ndc1t io11 nlgorit hrns is ,lit ;-\(lvanU1ge. In
~Jr1teraction9.tI~ilntClg:aphs and overhead contact lines
-1-56
-1Q:'l,J/m
200 - --------·N/(ms ·2 ) 100 70 40 20
1 co
10 7
c
4
en en
E
8:?
co Q_ Q_
<(
2
0,7 10 3 N/m
0,4
2
4
6 7
10
20
40
60
Hz
Frequency------
Figure 9.11: Dynamic apparent mass of pantograph designs SBS 65 and DSA 350
the other models, excitation patterns can be determined by carrying out harmonics analysis. In addition to the measurements mentioned above, the phase responses of the dynamic apparent masses are also determined to take into account the inertia of transmission at the individual frequencies.
9.3.3
Contact line system models
9.3.3.1
Basic considerations
Frequently, simple contact line system models are nsed \\hen analysing pantograph behaviouL A model which was used for optimizing the high-speed pantograph for the ICE is described in reference [9.13]. In this rnodeL the contact wire is treated as a taut string Qf zero mass stretched between the dropp<'rs. The contact wire masses are assumed to be concentrated at the dropper positions. The droppers are modelled as dampers at the contact wire suspension points and t lie' steady arms as springs and dampers. The CcHenary wire is not taken into ac-connt in this model. The model does not permit the m·erheacl contact line in~ tallatiou to h<~ <111alysed per se because it does not consider tlie d:vnamic behaviour or the mt P11cu, wires ;-we! stitch wires . The contact force functions ded11C'.ed using such simplifi<'d t110dds therefore do not describe anv rc'sponses due to the catPnary a.ad stitd1 ,rir<'s ;-uid at<' 1tot wrv usefol for predicting IH'haviour aJ, high spe<'ds
457
Iu the following, fom couta.rt, li1w syst<~m models will be presented that take into consideration all essential paranwt
9.3.3.2
Modelling with the aid of the finite-element method [9.16]
In case of the .finite elernent method the overhead contact line equipment is subdivided into differential elements which are linked by coupling mechanisms easily described in mathematical terms. This leads to a system of differential equations which permits modelling of the overhead contact line installation to be created with any desired level of accuracy. However, since the elements selected must be small enough to permit the study of the dynamic processes, systems of more than 2000 differential equations would need to be solved for a complete tensioning length. The moving excitation point means that the system description matrices are time-dependent and must be re-formulated for each point of contact. The solution of these problems requires complex calculation procedures. Models of this kind are successfully used for calculating stationary processes, e.g. for calculations of elasticity [9.17]. They have also been used for dynami<.: calculations, e.g. as reported in references [9.18] and [9.19]. However, to reduce the calculating tirne in these cases, the wire between the droppers was not further broken down into individual elements but substituted by rod or string elerrn~nts. This achieves good model detail but can lead to errors, particularly when modelling effects of parameters in the higher frequency ranges.
9.3.3.3
Analytical solution in the frequency area [9.14]
Analytical solution in the frequency area is based on a contact line system of infinite length, which is supported by jointed supports at finite spacings. The individual sections are allowed to oscillate independently. The associated Lagrange's erruaiwn8 ctre solved by means of a Ritz approximation method. The accuracy of the solution obtained is determined by the order of the approximation approach. An order of 90 was used in calculation examples for three longitudinal spans in [9.14]. Computer calculations for a complete tensioning section would take a long time. Fourier solutions of higher orders are used to model the rnupling between the wire and the pantograph Lo calculate the contact forces. This further increases calculation complexity and cornp11t.er loads. The model has been used for opti111izing pantograph parameters. Any modification of contact line system panu11ct<~rs is very cornplicated.
9.3.3.4
Method using frequency-dependent finite elements
The method using fre1ru,enr:y 1fr111"11dcnt finite dc'//1,en/;s is basl'd on a 111odel as d<'Scrilwd i11 section 9.3.:3.2. lt was iul rod1wf'd willi the objectiw of r<'duc-ing 111<' order of the rn;d,ric<'s tl(!<'d<'d i11 !lie <11t,dYsic; oft It<' liigh<'1-frcqt1<'IW\ prn<<'SS<'S. wliil<· rdai11ing tit<'
9 Interaction of pantographs and overhead contact lines
458 elements:
tension pole
~
springs
•
masses
suspension pole
conductors
Figure 9.12: Equivalent model scheme describing the oscillation of a catenary contact line installation
universal applicability of the method [9.7]. The tensioned string equation is solved analytically at the element level so that it is not necessary to subdivide the sections of the contact wire between the dropper locations. For the entire overhead contact line installation, frequency-dependent matrfres are derived which account for additional elements e.g. steady arms, clips, cantilevers etc. as individual masses or oscillating elements. This enables any type of contact line system to be modelled. To begin with, the natural frequencies and the corresponding natural vectors of the overhead contact line are calculated. The reaction of the contact line system to excitation by the pantograph can be determined by superimposing the independent responses at individual natural frequencies. In this method, the majority of the effort involves calculating the natural frequencies and vectors but this only has to be done once for a given overhead contact line configuration. An iterative approach is used to calculate the reactions to a force acting on the analytically modelled contact \\·ire sections. 9.3.3.5
Modelling on the basis of d'Alambert's wave equations [9.5]
The contact force deflects the contact wire and this deflection is propagated along the contact wire at the wave propagation velocity. It is reflected by discontinuities such as droppers and is also transmitted to other wires by these components (also refer to clause 9.2.5). At the point of contact, the pantograph will respond to impulses in a specific way. This model is based on d 'Alambert 's wave equation and available as a computer model and can be used as a catenary system model [9.3]. The motions of the elements of the catenary system are obtained by superposition of the individual waves. The realistic representation of the dropper wires as string elements. which can only exert tensile forces, is a major advantage here. However, the significance of dropper wires going slack and the consequent affect on the contact force is assessed differently by various authors in their respective publications. The calculation effort for this model is high for complex contact line systems and increases even further if \·,nving dropper spacings have to be taken into considnation.
9.3.4
Overhead contact line installation frequency-dependent finite elements
9.3.4.1
Mathematical description
111odels
using
As an example of a metlwd ul simulating the interaction of pamngrelplis and ov
~.~
~.~
v,t_~-H
t_r;_ _ _m_·_ _ _
H
-,~ 0
r-;=--
I
X
0
Figure 9.13: Differential element of conductors with degrees of freedom z1 and z 2 at the boundaries
described in greater detail [9.12]. From a dynamic aspect with respect to oscillation characteristics, a vertical contact line installation can be modelled by a plane substitute system comprising individual masses and springs as shown in Figure 9.12. The conductor elements interconnect the mass nodes and are described by their mass per unit length m' and their tensile force H0 . Their stiffness is considered to be negligible [9.16]. All other elements can be modelled by spring elements and masses as oscillating finite elements. The excitation can be applied at any point along the contact wire, either along a wire element or at a dropper position. The motion transmission behaviour of the wires is described in terms of the frequency [9.20]. In this sub-clause, only the most important relationships can be presented. The approach is based on a conductor element as shown in Figure 9.13, of length l stretched between coupling points 1 and 2 and characterized by a tensile force and a specific mass per unit length. The equation of motion of taut strings (equation 9.4) applies to this element, expressed here as:
,.. H II my- oY
(9.64)
0
in which jj = fJ 2 y/fJt 2 and y" - fJ 2 y/fJ.rc 2 . To solve this equation, it is transformed into a frequency function using the assumption y = z · ei wt.. In the frequency area, this leads to a time-independent differential equation of the second order
Hoz + f/
12 mw z
= (')
(9.65)
Using the solution
z(x, w)
= A sin /3.T + B cos f3:.r
J
with /3 = w / ccw = w / H0 /'m' and the boundary conditions z z = z2 for :r = l, from which it can be deduced that
B - z1
and
=
z 1 for x
0, and
A = z2 / sin (3l - z 1 · cos f3l/ sin f3l
the general solution is obtained
z = z1 ( cos /3:r - cot (-3/ sin fh) + ,: 2 sin /3:i: / sin (3l
(9.66)
The sum of all forces d11e to inertia and reaction forces yields the~ node force .fr
f. =
'z
r:r + 11(
• z
(9.67)
'/,
By separating the para1ncters and applying the transfor functions .Yi and .Yk, we obtain l /
·'/' 1
=
2
--w ·
~'
I
L__, 111 :,,: /,:
/ (I
_!Jilfk
d.r
9 Interaction _()f pantographs and overhead contact lines ________________ _
460 ~::.__
\Vhen the substitute masses are introduced, this is transformed to
Then, the elements of the mass matrix can be determined from l
m'
mik
j
.9i.9k
d:r:
(9.68)
0
Analogous to this, the 8pring elasticity coefficients are described by l
ft=
L
zk ·
k
Ho
J
g~g~ dx
0
and
which leads to the following equation describing the spring elasticity coefficients at the coupling points l
cik
= Ho j
g~g~dx
(9.69)
0
Expressed as a matrix equation, the equilibrium of forces at the nodes is
F
= (-w 2 M
c) Z = C(w)Z
(9.70)
This form of modelling with masses at the connecting nodes and elastic springs between the coupling points permits additional elements to be introduced by adding further springs and masses. Then it can be used to calculate the behaviour of any desired network of masses, inelastic strings and elastic springs. The system of equations is solved with the aid of natural vectors. This, is done by determining the natural frequencies using (9.71)
and then the natural vectors of the system corresponding to these natural frequencies ·will be
(9. 72) The natural frequencies are cakulated using a complex numerical iteration algorithm. The frequency determinant must be solved many times in order to find the zero values by iteration. These have to be as determined as accuratel:v as possible, since this is the precondition for finding the I1atura.l vectors.
461
Forces exerted externally arc taken into consideration by th0 discrete equation of motion (9.73) which has to be solved individually for each natural frequency. The motions at the individual frequencies are then superimposed to obtain the overall reaction. To solve this equation, the motion is substituted by the modal node reactions Yn (t)
which leads to the expression (9.74) In this, the excitation vector will be
-
1
m,n
~ L.., i
Foi-lV-i
(9. 75)
with the modal mass
and the weighting function which corresponds to the locations of application of the excitation forces between the nodes i and k (9.76) in which /3n = w 11 / Cp and Cp is the wave propagation speed of the respective conductors, that of the contact wire being usually used. This approach permits simultaneous excitations of the system at multiple points to be taken into account. As a rule, this calls for the definition of the modal damping coefficient, which is a function of the frequency. However, for overhead contact line equipment ,rith ,·ery little damping, a corn,tant value of 1 % can be assumed for the damping coefficient at all frequencies.
Using the excitation force F as a basis, the respective differential equations need to be solved for all natural frequencies and the results for the individual frequencies are then s11perirnposed to obtain the overall reaction of the contact line system. The motion of ;-w_v desired point ca11 be detcrn1ined 11si11g equation (9.65). Due to the use of timeindependent system !llat.rices in the fr<)
462 9 Interaction of f~cl:ntographs and overhead contact lines ..::..::.:=-----------------------
~-----6_:_~_;_7____=)-~
Figure 9.14: Overhead contact line equipment of standard type Re 2S0, all dimensions in metres
1,0
Cf) Cf)
(ll
E
c
~
(ll
Cl. Cl.
(ll
0 ll)
:::J
~ ~
e!
eCl. 0
&!
II I
0,0 0
2
I
111 I
I
4
ii.
. ,1, 6
.!Ii..illlr
1111,
8 10 12 Natural frequency - - - - - - -
)\,
rll1,l1
I
14
16
18
Hz
20
Figure 9.15: Natural frequencies and the related modal masses for a Re250 overhead contact line type
9.3.4.2
Natural frequency calculation example
The method described above has been used to calculate the natural frequencies of the Re 250 contact line type as shown in Figure 9.14. Figure 9.15 shows the first 200 natural frequency values obtained. In this graph, the abscissa denotes the frequencies and the ordinate the reciprocal values of the modal masses expressed as a fraction of the maximum value. With this, the graph indicates a ,veighting of the effect of the respective natural frequencies on the motion behaviour. It is noticeable that the motion behaviour of this overhead contact line type is only slightly affected by the natural frequencies above 12 Hz. Figure 9. lG shows the natural frequencies of a similar contact line design but without a stitch wire. It can be seen from the comparison with F'igure 9.15 that this slight modification or the contact line structure results in a stiffer r<)action. The higher frequenci<)S an~ rnon~ pronounced.
!:l_:~ Si!uulation of interaction of overt10~_c2!1t,act lines and pantographs 463 ------~-~~----------..:.:::::: 1,0
(/)
(/)
(1J
E
c
(1J
ro
Q_ Q_ (1J
0 11)
:::, cij
>
~ ~ ~ cij 0
eQ0 11)
a:
,I
.I
0,0 0
2
11,I 4
11111 ..
6
.I
II
I, Ill,,
111.
111111
8 10 12 Natural frequency - - - - -
II
\ 14
16
18
id Hz
20
Figure 9.16: Natural frequencies and the related modal masses for a Re 250 overhead contact line type, but without stitch wires
9.3.4.3
Contact force calculation
The models which were presented for the contact line and pantograph sub-systems can be used to determine the motions of the components of the sub-systems resulting from application of an excitation force. The coupling characteristics at the point of contact are determined by the excitation of one sub-system due to the motion of the other sub-system. Thus the contact force calculation is carried out by iteration. Figure 9.17 shows the calculation procedure adopted. The contact line is described by the natural frequencies and the natural vectors. The initial values are obtained from the position of the contact line when at rest, which can be statically determined from conductor masses and forces as well from the length of the droppers. The contact wire is held at the specified height by the droppers at their positions and sags along the sections betweeu the droppers. The bending elasticity of the contact wire is also taken into consideration between the droppers to avoid discontinuities in the contact wire curve and associated contact force effects at the dropper positions. The contact force Bim:ulation is now carried out step by step. The train speed is used to calculate the position of the individual contact points for each step. The static pantograph forces 01 the forces acting in the preceding time step are used as initial values. For these excitation forces, tlw displacernents of the contact wire at all contact points are calculated for t.hc natural freq11encies and then s11perimposecL The pantograph 'Tnotion is dctenniued ill the sauw wa,. 'The contact force assumptions enc changed iteratively until the pantograph a.nd <·ontact wire displacements at each individual contact point 1u;1t.cl1. For pautognipli~; and a sing!<) contact point, 15 to 20 it<'rntioll cycles are needed ;t11d this is a.lso Lil(' ms<' !'rn i111iltipl<'. pallt.ographs which ar<' !"11rtli<'t thall 10 t11 apart..
9 Interaction of pantographs and overhead contact lines
464
--=::'...~------------------
Formulation of the matrices and vectors, determination of initial values for the pantograph and the contact line installation
Determination of the the contact wire stationary position as initial values for the differential equations
To be repeated for each lime/distance step
0)
f:? 90 2 0C1)
c0
0
0 -l--+-+-;-+-t-+-+-+--+-~-..-.t-+-+-+-+-+-+---+-+--'-l
Pantograph travel x -----
Determination of the excitation rosition, determination of initial values of the dynamic forces for all the pantographs
For each of the natural frequencies Calculation of the excitation vectors for all the pantographs Solving the diffferential equations for the natural frequencies Pantograph travel x - - Calculation of the displacements for the natural frequencies
Superimposing all the contact wire movements for all contact points
Figure 9.18: Pattern of the contact force F and the contact wire uplift (upward displacement) y for a pantograph design SBS 81 moving along a overhead contact line type Re 250 at 200 km/h
For all pantographs Solving the differtial equations for the pantographs Calculation of the pantograph displacements
r:o
ITT 11II11'.6'11
I
I
I U 11111 RI I I 11 :E0:ITI
LL 0)
f:? 90
-+-tcHHJ.,..,,_,lt-'t-
_f>
0
C1)
Comparing the pantograph and contact wire displacements for all contact points
c0 0
0+-+--+-t-+-+-+--IH--+----,---+--+-+--+-+--+--J-.....+-+-"--+-+--+--Jl-+-+--+---1
Pantograph travel x - Iterative correction of the dynamic force approximation
Storing results for each time step
A
,,,-----,,..,---.., Graphic plot
;\::
0..
~---------______,---
0
::i
End
Figure 9.17: Iterative contact force calculation
-50 Pantograph travel x -
Figure 9.19: As figure 9.18, but with a section insulator a.t point A
9.3 Si11!tilation of interaction of overheacI.<:~1~act li1_10:~-~1~~l_pantographs
465
---------=
Pantograph travel x _.,_
.e Q)
[:' 90 2 t5 (1l
c0 u
-11-;--/q,fW-ffll-flH+HII
0-f-l-lc-+--t-+-+-+-+--+--+-+-+-+-+-'+-t-i-l-f-+--<-l-t-+--+--+-+-+-+-+-t
Pantograph travel x - -
~
0-+----------------1
ci ::::i
-50
+-+--+--+-+-+--+--+-r-+--->---+-<-+-+----,....,.-+-+-+--+-+-+--+-+->--+-,-+-+-+--<
Pantograph travel x - -
9.3.4.4
Figure 9.20: Contact force curve of two pantographs moving along an overhead contact line of design Re 250, F 1 leading, F2 trailing
Examples for contact force calculations
Figure 9.18 shows the contact force graph and the contact wire displacement from its static position due to a pantograph model SBS 81 moving along a section of an overhead contact line of design Re 250 at a speed of 200 km/h. The band width of the contact forces is greater than the values obtained by measurements. But when assessing these results, it must be remembered that any measurement system will record dynamic effects in a dampened and therefore smoothed form. Figure 9.19 shows the effect of a discontinuity in the overhead contact line equipment, in this case a section insulator which has been simulated by an equivalent mass, all other conditions being the same as for Figure 9.18. The decrease of the contact vvire displacement and the disturbance of the contact force curve in the vicinity of the section insulator can be seen clearly. Figure 9.20 shows the results of a sirnulation of two pantographs travelling along a Re 250 contact line system at 200 km/h. It can be seen that the trailing pantograph moves far less smoothly. This pantograph may even experience a loss of contact force at th<~ last dropper of a span. The calculation examples prove that the model of the interaction of the sub-systems; overhead contact line installation and pantograph presented above, provides an adequate description while requiring an acceptable level of calculation effort, only. The approach cau he used to investigate how variations of pa.rameters or the individual :-mh-s\·stcms affect the contact behaviour.
466
9.4 9.4.1
. 9 Interaction of pantographs and overhead contact lines
Measurements and tests Introduction
In parallel to the theoretical study of interaction between pantographs and overhead contact lines, measurement techniques have been developed for assessing the quality of current transmission. For this purpose three aspects can be defined: assessment of the contact line alone, - assessment of the pantograph alone and - assessment of interaction of these two components. The compliance with safety related limits assumed, a high power transmission quality is achieved when the energy is transmitted: continuously without voltage or wrrent drops or losses. This means that a mechanical contact must exist at all times. If the mechanical contact is lost, arcing occurs initially. An electrical arc is environmentally disturbing, causes interference and increased wear but ensures that the current flow is upheld and is thus of fundamental importance for energy transmission between moving contacts. If the air gap becomes to long and the current is interrupted, the \·ehicle drive is switched off and traction power is lost. The number and duration of arcs is a criterion for assessing the quality of energy transmission. without leading to unacceptable environmental disturbances. Arcing is associated with the emission of high frequency electromagnetic wa\·es which can interfere with amplitude-modulated radio transmissions at frequencies up to 30 MHz. At the same time, audible noise is generated, but this is generally blanketed by the general train noise. without causing wear of the components involved, i.e. contact wire and pantograph, to an extent which is economically inacceptable. Such wear can be due to arcing and/or too large contact forces. Arcing occurs when the contact force approaches zero and is lost completely. In contrast, the contact force must not be too great as this would also lead to the contact wire system being lifted too high and cause unacceptable wear. This means that the contact force is the definitive physical quantity by which interaction of the pantograph and overhead contact line can be assessed. In principal, the physical quantity used to judge the quality should meet some other general criteria: As far as possible, the respective characteristic quantity should pro\·ide a continuous, gradual scale of assessment which allows not just a ;'Yes/No'· decision, but also the evaluation of quality variation. It should be possible to measure the respective quantity and to carry out forecast calculations on simulation models in order to be able to compare measurements and calculated results. Measurements of the respective quantity should be reproducible and not affected by any random factors. lVIeasurcments repeated under comparable conditions should lead to comparable results. It must be possible to measure the assessment q11autity or q11autities 011 an active, live pantograph.
9AMeasmements andtests ______________
467
In earlier references [9.21, 9.22], the quantity and duration of the arcs, measured as voltage losses, were the physical quantities used to assess the contact behaviour. However, these quantities do not meet any of the criteria listed above. If no arcs or only relatively few arcs occur, this characteristic is completely unsuitable for use in system comparisons. It is not possible to simulate arcing and measurements have shown that it is not possible to reproduce the results in repeated test runs. Even under identical conditions on the same lines, repeated tests yield different results. The contact force couples the two mechanical systems contact line equipment and pantograph - both of which are capable of oscillating and which have various masses, coefficients of elasticity, damping coefficients and natural frequencies. The pantograph lifts the overhead contact line by an amount which is a function of the contact line elasticity. The fact that the elasticity varies along the length of the contact line, leads to periodic upward and downward movement of the pantograph head and the amplitude of this motion, depends on the lifting force itself. Mass inertia forces, which are a function of the rate of change of the vertical motion, are superimposed on this mean lifting force (see section 9.3). As speeds increase, the contact force is effected more and more strongly by the dynamic components. In order to keep the collector strips moving along and in continuous contact with the contact wire, the contact force values must remain within a certain range, i.e. the dynamic range. The variation with time of the contact force is the definitive characteristic quantity with which the dynamic behaviour of the system components and their interaction can be evaluated. In parallel to theoretical studies [9.23, 9.24] on the dynamic motion, the German Railway Research Institute, located in Munich, (Versuchsanstalt der Deutsche Bahn AG) developed a force measurement method [9.2, 9.25]. Since 1980, after a successful test phase, this measurement system has been used by the DB and other railway operators since 1980. In addition to the contact force, other characteristic quantities have been introduced as criteria for evaluating the pantograph and overhead contact line interaction: the overhead contact line uplift, the pantograph's vertical motions, the contact behaviour of the pantograph head or collector strips expressed in terms of the frequency and dm-rdion of power losse8 when trains travel without traction power (sec' [9.21, 9.22]) and for higher train speeds by monitoring arcing (see [9.26]). All these are secondary quantities and result from the respectiw reac:tion to the continuous variations in the contact force ·which couples the two oscillating systems: overhead contact line and pautograph. The uplift of th(' contact wire lw the pantograph is recorded eitlwr stationar:-dy by a rneasmiug unit install('d at a support (see clause 9.4.5.J) or mohih· bv an optical measuring system installed dose to the pantograph on a traction unit (see clause 9.4.5.2). Separate assc\ss,nent of the contact lin(~ alone is mainly c-anied out hv n\corcling the nm!ru:! wzn: t:11:t.!wl 11osifl011. and by calculating the wntact li n.r: elastir:'ity based on t.lw 11plif! rem, d<'d for an applied cont.ad. force. In addition 1l1e rn1nponent.s of the
9 Interaction of pa.11tographs_and overl1ead contact lines
-168
contact line are checked in regular intervals. Especially tlw position of the steady and registration arms as well as the clearances of live comporn~nts to structures and tunnel walls must be checked. Inadmissible, too high or too low contact forces result in increased wear of the contact wire. The wear is determined by measuring the resuiual contact wire dirnensfon . .Assessment of pantograph alone as a separate component is carried out on a pantograph test stand (see clause 9.4.4). There, the oscillation performance of the pantograph is tested within the range of relevant amplitudes and frequencies.
9.4.2
Contact force measurements
9.4.2.1
Basic principles
The contact force occurring between contact wire and collector strip cannot be recorded directly because of the moving contact spot. Due to the simplier possibilities of monitoring and because of developments carried out in the past very often the sum of the collector strip reaction forces, the so-called internal forces, is taken as an approximation quantity instead of the contact forces themselves. For contact force measurements sensors are installed directly at the connection of the collector strip socket and the collector strips themselves. The mass inertial forces acting at the collector strips and the running-speed-dependant aerodynamic forces of the collector strips are not recorded by the force sensors. To determine the contact force, a dynamic correction quantity has to be added to the internal force which is evaluated from the collector strip acceleration and takes care of the inertial forces of the collector strips ( dynmnic correction). Additionally, aerodynamic correction quantities depending on the running speed have to be considered, which are evaluated according to the procedure described in clause 9.4.2.3. To enable comparisons between results obtained with different pantographs or by measuring systems with differing arrangements of the force sensors and to judge them based on the same criteria dynamic and aerodynamic corrections cannot be waived. Conditions and requirements for measuring systems for contact forces are stipulated by EN 50 318 [9.27]. 9.4.2.2
Measuring technology
The recording sy"tem described in [9.25] is based on proposals made in [9.28]. Figure 9.21 shows a schematic presentation of the contact for-ce mea.mrement system, which has been used successfully by Deutsche Bahn AG for several years. The sensors arranged at the collector strips are the most important components of the system (see Figure 9.22). Pantograph heads equipp<\d with two collector strips need four sensors for monitoring the internal forces. Special cables connect the sensors ,vith the amplifiers which are arranged in a casing mounted 011 the pantograph base. There, the measurement signals are converted into a form that permits them to be transmitted from the high-vol tag<·'. potential equipment to earth potential equipment b:v means of an optical link a.nd galvanic d<·co11pliug. \,\!itl1in the trnctio11 1111it, tlw optical signals
9.4 Measurements and tests
Pantograph
Roof of traction unit
High voltage
- --!-Earth potential
(
469
Sensors
)
L _ t_
Power supply of sensors Signal adjustment
Optical transmitter
- - -
Insulators -
- - -
Optical receiver Line driver
Measuring car Normalising of measuring signals Calculation circuits
Analogous measuring quantities
220V-
Figure 9.21: Schematic diagram of the system used to measure contact forces between the contact wire and the pantograph
Figure 9.22: Force sensors of the contact force measuring system
received are converted back into electrical signals and passed to the measuring car [9.2] for further processing. For example, from these signals the individual forces, the sum of the forces and the location of the contact spot on the collector strip are dett·rmined, recorded and printed. T'he recording sensors arranged at the pantograph must comply with the follmving n)quirements:
they must have minim111n effect on the original dirnensions or mass of th<' pantograph head and not change the behaviour of the pantograph head in anv unacceptable way. the SC)nsors must be abl<' to 111casm<' sla/;ic and dynwnic: fon:cs; <'11viroumcnL-ll effe< ts, <' g . wid<' Yariations of arnlii<'nt t<:~1t1p<~ratures or strong
470
force sensor
force sensor
·-----------------:F2
(L'--)
Fz 2 8
;,-----
M(y)
= F2 ~
Q(y)
= F2 dM(y) = fz..
M(y)
Q(y)
(a)
dy
(b) ----
(c)
2
0, left side 0, right side
Figure 9.23: Shear forces and moments acting along a collector strip. a corresponds to a rigid fixing, b corresponds to a completely flexible support, c corresponds to the real collector strip fixing conditions, Q shearing force left side, Q shearing force right side
electrical and electromagnetic fields at traction currents up to 1000 A. should not have any negative effect; the vertical force components must be measured without being effected by other forces acting horizontally on the collector strips. Figure 9.23 shows the forces and moments acting on a collector strip. The strains in a bending bar-type sensor are determined by the moments acting on the sensors. Since the bending moment curve passes through zero at two points near the sensors and the locations of the zero positions depend on the stiffness of the support fixing, and the point of application of the contact force. This results in complicated relationships between the applied force and the measured values. Figure 9.23 illustrates that the relationships between the shear forces and the applied forces are less complex. The sum of the shear forces is equal to the applied forces and is independent of the contact force position and the boundary condition at the end fixing. To ensure reliable measurements, force sensors able to measure the shear forces independently of the moments are necessary. The shear forces cause shear stresses in the lateral sides of beam elements with maxima under an angle of 45° to the vertical axis. By means of special strain gauges, the deformatiou (elongation or compression caused by the shear forces) can be recorded from which a measuring value proportional to tlw ar-ting shear force ean be deduced. Strain gauge sensors are passive sensors and require a separate supply \·oltage and amplifiers. For example, a force variation of 10 N results in a variaLion of the diagonal bridge voltage of the strain gauge~ of oul,v GO
,,Y.
The sensors are at high-voltag!' pot<(nt.i,1! (:3 kV to 2G kV). In the vicinit\· of the con-
9.4 Measurements and tests
471
Figure 9.24: Arrangement of the signal processing unit with bushing insulator (right) and voltage transmitter
tact wire strong electrical and electromagnetic alternating fields occur due to the high alternating currents and electrical arcing. To minimize induced interference before amplification of the signal, adequate shielding of the electrical connection to and from the sensors must be utilised. It is also useful to amplify the diagonal bridge signal of the strain gauge sensors as close as possible to their origin. Therefore, the bridge amplifiers are integrated into a casing installed on the traction unit roof above the insulators (Figure 9.24). The casing is also required for downstream electronic devices. A multi-core, 4 m long cable is used for the connection between the sensors, amplifier and power supply. Due to the adverse environmental conditions at the pantograph, technical requirements of the input amplifier concerning common mode rejection and temperature stability are modified. For an ampl~fication factor of 500, a common mode rejectfon factor of 110 dB and a temperature drift of less than 1,5 µV /K must be achieved. To fully utilize this amplification, the sensors must be tuned in the installed condition such that the residual no-load bridge voltage will be a few m V only. An optimurn design of the input arnpli.fier assumes that signals of forces with high amplitudes ( up to 1000 N) can be processed without the amplifier going into overrange. The amplifier output signals are converted to frequency-analogous digdal signals and passed to an optical fibre link by meaus of light-emitting diodes (LED) necessary for galvanic decoupling between high-voltage potential and earth potential. The optical fibres are guided through a bushing insulator for protection against pollution and damage. At the eartlt potential end of the insulator, the optical signals arc rnnvcrtecl back into electrical signals by photo-sensors and passed to the testing and nu:a,.<;·11,n,ng car via cable. In the measuring car, th<' frequency-analogous electrical signals are re-converted to analogue 111eas11n~mcut signals b.r means of frequency /voltage couversion. The analogue signal;-; arc an aCTt1rnte r<:pr<'s<'t1tation of the shear fon:es occmri11g at the~ four force sensors nud of' the foff<'S acting at t It(' collector strips s11ppott
__ 9 Interaction of pantographs __and_ overhead contact lines
-1,2 ------------------X
F1
I
F2 I
J~
+ F2 Fl /
-- [ y
;
:
I
' F4
\ F3: F3 + F41
I I I I I
I I I I
Ys
I
I
I
: 1
I
F2 1 -1- F2
I I I 11
+ F4 F1 + F3 : + F3 + F4 F1 + F2 -1- F3 + F
""-
/
I
I
I I I I 11
~H~~---~-~~~~H~
t
2 1---~~-++~I,-I,-I.,..1lc+---,-1---,-1~1~l~I1.--,1-;..il
a,
_ _ L_LLiLUL
:i
b) I
I
I I I I II
~11--==l=~:.:r;~'P-!-'l"j---'--+==t=t=-t-ttil-H 2: I I I 1111 -a)-,--1-T1T1IT
Q)
u
0
LL
ys
---""''-----------~----
10 Frequency-
Contact wire displacement
Figure 9.25: Determination of the contact wire position on the basis of the forces measured
Hz 100
Figure 9.26: Amplitude of transfer function. a without and b with dynamic contact force correction. 1) Module of Frecorded / Fcontact
Due to the steady technical progress in the field of electronics within the last few years, highly efficient integrated modules have been developed. These modules can include the complete electronics for signal processing and can be miniaturised so they can be arranged directly at the force sensors. The electronic modules already supply a frequency analogue digital output signal which can be transmitted from the collector strips to the optical conversion unit arranged at the pantograph base frame almost without disturbance. 9.4.2.3
Measured quantities
Internal forces
Primary measuring quantities are the react'ion forces at the supports of the collector strips. If the forces acting on collector strip I are designated F 1 and F2 (Figure 9.25) and those acting on collector strip moment II are designated F3 and F 4 the analogue addition of the forces acting on the collector strips leads to the internal forces exerted by the contact wire.
as well as for a total force on both coll<~c-tor strips
1~ = Fs,
+ l~rt
9A l\foasurcmeI1t.s and tests _____________
The position where the contad force is applied can be determined from the relationship between the difference of the sum of the summed up individual forces on the left and on the right side to the total force: ., (F1 + F3) - (g + Fi) is = ks...C.--------. . F1 + F2 + F;3 + Fi
(9.77)
where } 5 is the distance of the contact wire from an imaginary central axis 011 both collector strips. The factor ks, which has the unit of a length, serves as a calibration quantity.
Contact force The relationship between acting contact force and measured internal force, valid under static conditions, is valid only for low frequencies in the case of dynamic processes (see Figure 9.26, curve a). The relationships between input amplitudes and recorded force and phase shift are functions of the frequencies. The relationships may vary greatly for individual pantograph systems and can be determined for example, on a pantograph test stand as described in clause 9.4.4. \Vhen measuring the collector strip acceleration i in the vertical (z) direction simultaneously and correcting them according to (9.78) with the mass inertia forces Fmsz resulting from the collector strip masses, the amplitude curve of the transfer function and, therefore, the measuring precision of the contact force, will be improved significantly (see Figure 9.26, curve b ). The contact force Fi< is obtained from
FI<
= Fs + F'msz = Fs + is · ms
(9.78)
where -:-s ms
is the mean acceleration [(i 1 + i2 + Z3 + i4)/4]; the related mass of the force sensors (msr + rns 11 ); ::: t, 2 ,3 ,4 the acceleration at the position of the force sensors and msr, rnsII the masses of the collector strips I and II.
To correct the recorded internal force, acceleration sensors are installed at the collector strips or at the force sensors already located there. The output signals of the forc<\ and acceleration sensors are separately available. Correction of signals is done by processing them according to the formula given by above signal circuitr_,· which enables linear filtering to the phase also in the limit and blocking state. Figure 9.27 demonstrates the difference in measured results of contact force' befor<\ and after applying dynamic- correction to intcrna.l force measurements. The pattern of the two curves coincides in principle. How(:V<'r, tlw contact forces show cousidNahl_,· more high-frequency signal con1ponents than tl1e internal forces. The lll<'asured pcuam<~tcrs and the valiws d(~rived along the t<'sted track sections are logged using graphic r<'.tord(~rs [9.2]. Figure 9.28 shows an example of such a recording. 111 addition to so111e gen<'ral i11formatio11 011 the tested stretch of the li11<' the record contains thC' following inforrnatio11·
9 Interaction of pantographs and overhead contact lines
200,------,-----,-----,----,
:o
t1
1------+----t---------t-------t
200,------,----~------,---~
t 1~o
1-t--.--;-1---rlt-------:--c--tt----c--,--1
(]_)
(l)
u
E
.£ 100 l-+-·fr/-lltttl,'V-'1 i"'rllfti\"atrl-rWl---tTHft:f
2100
0 co
0 co
1
§
50 1 - - - - - - - t - - - - - t - - - - - + - - - - - l
§
50 1-------1----+----+---------l
(.)
(.)
fooo
1800
fooo
2000
m
Distance-
a)
1800
m
2000
Distance ------
b)
Figure 9.27: Record of forces during a test run. a) internal force between pantograph head and collector strip, b) contact force, dynamically corrected 140,0 km/h 051,000 km m 6, 00
MP
0
,80
"
,40
~
I
I
T I
I
I I
I
_,_
I
fff,2 I
1
-
I
l
I
vertical pantowaph movement
,00 ,80
140,5 km/h 052,000 km
1,0 km
I
I
I
I
)'supports
V
I
- --+
-
-- ----
I
I
ms
100t 20 10
2 (1)
X
I
N
00 00
*
,, I
~~!
..
II., d .. ,. i,L "If'• 'II"
--I, F
__ '--
1
F2
..,,, F3 F4
,,,,IIIJ 11,,,/,
.
I
Fs1
vw, Fs11
\,I..,__
I
dynamic force gra llfl
.. '""' rr'""
,,
.. ,11
,,,
"'"
" ...II/ti~.
...,_
,_. ""-~
IL
·"'"
.,,,1 ,_
11,..l
J ~ µII-<,_
I
'""
.
~
.~
~
~· ,,
..I
---
,.
'r-
.,
"
~
~;·\~'~?r°V"I r{, strPiot stretch
left curve
Figure 9.28: Record of a contact force test run. F Contact force CWH Contact wire height tare Duration of arcs 0 Overlapping section
running speed, distance travelled (line kilometres), symbols for particular characteristic points of the overhead contact line such as overlap sections (0), midpoint anchors (MP), points (W), etc, vertical pantograph nwtfon, arcmg, contact forces: total force Fs, sum of forces on lea.ding colkctor strip F.s 1, sum of forces on trailing collector st.rip F.s 11 ,
----~
9.4 Measmernents and t~s_~fl_ ___________ _
the four individual forces Fi, F2, 1'3, F,1. the dynamic lateral contact wire position relative to the collector strips, as calculated from the measured individual forces, overhead line contact line supports identified by vertical lines in the oscillogram. The evaluation of the results focuses on the graphs of the dynamic forces and particularly on the total force 1~ and FK, respectively. A precondition for superior pantograph running performance is a uniform distribution of the cont.act forces on both collector strips. This can be seen on the graph of the forces F.s, and Fsrr. The system for testing contact force performance is also able to measure the following features: the vertical position of the pantograph top tube as an approximation gained from the recorded support tube angle, the horizontal for-ces acting on each collector strip in track axis direction (forces due to wind and friction), the vertical acceleration of each collector strip (for dynamic correction), the vertical acceleration of the foot of the pantograph as a quantity for assessing the effect caused by irregularities in the track superstructure. The vertical movements of the pantograph along the contact line equipment have a close correlation to the forces. A uniform pattern for the uplift characterizes smooth running of a pantograph with small dynamic force variations. \i\Tith the quantities described above, a comprehensive representation of the contact performance and the reasons for irregularities and disturbances can be given.
9.4.2.4
Correction of the aerodynamic collector strip uplift
Since the force sensors for recording the contact force are arranged underneath the collector strips, the aerodynamic uplift and downwards force., acting from the collector strips to the contact wire can not be detected by the force sensors. To be able to consider the running-speed-dependent aerodynamic force components, a speed-dependent correction factor must be added to the recorded contact force. The aerodynarnic uplift force component is determined by measuring the uplift force according to the UIC rules [9.29]. To carry out this measurement, a pantograph equipped with a contact force measmement device is fixed by two ropes attached to a collector strip, each such that the collector strips will not touch the contact ·wire dming the test run. The co~lector strips are fixed vertically (see Figure 9.29). The distance between the collector strips and the contact wire is approximately 100 mm. At the upper ends of both ropes, winding devices are arranged which are fixed to load cells. The load cells are used to record the forces transferred by the rnpe to the collector strips. Simultaneously, the internal forces underneath the collector strips are recorded by the contact force measuring system. The aerodynarnic cmnponent of !he. , ertical force (Fae,o) results from the difference of the force recorded via LIH) two ropes (Fiope) and the internal force ( f"') recorded by the contact force' mPasuriug systciu. Using this measuring prncedm<\ the aerodynamic components of the v<~rtical forces acting on the pantograph collc~rl.or strips arc detennin<~d relative' to tll(' rn1111i11g speed, the
9 Interaction of pantographs and overhead contact lines
-1,6
-----I---.-I------_
C::/ contact wire
_
I
Faero
-
collector strip
""-t-""---........::------""+..,___ pantograph head
string I
/
string II -
--
/
Figure 9.29: Determination of the aerodynamic force components acting at the collector strips of the pantograph by measuring the forces in ropes which fix the collector strips. a) units to measure the forces between collector strips and pantograph head; b) units to measure the tensile forces at the strings
running direction (knuckle in running direction/knuckle opposite to tunning direction) as well as on the arrangement of the pantographs on the train. The aerodynamic force component has to be considered when carrying out test runs with pantographs raised at the contact wire.
9.4.2.5
Evaluation and assessment of the measurement results
The dynamic contact force variations are superimposed on the static and aerodynamic forces and will vary to either side of the mean force of the latter (Figure 2.14). The overhead contact line with the running pantograph represent a moving system capable of oscillation. The force variations due to the interaction of overhead contact line and pantograph depend on the train speed, and on the design and relevant features of the t,rn systems involvecL As a result, the contact force variation measurements can be used to assess the quality of differing overhead contact line and pantograph designs. The follmving statistical criteria of the forces can be used in the assessment: the arithmetic m,ean and the route mean square value, the .sta:ndarcl de·uw,hon, thr deviation from the mean value, the e.clr'emc values (maximum and minimum contact force values). The analogous graphical force recordings obtained along the contact line installation do not nro\·icle am of these values except for the extreme vctlues. However, the required quantities C'clll lw obtaim'.cl b,v statistical methods. The evaluation of the cumulative frequency \·alues of lli('.a:'i11re1twnt S(\ri
477
or
value x, standard deviation s and the distribution the contact forces a.re determined. Tlw standard deviation cau be introduced as a direct criterion for judging the contact performance. From the ideal goal that the contact force should be constant, it follows that the lower the standard deviation the better the contact performance will be. The standard deviation aud tlw mean contact force can be used to establish limits for dynamic ranges whereby the following characteristics of the frequency distribution apply: G8,3 % of all co11tact force values are between x s and x s, 95,5 % of all contact force values arc between x 2s and x 2 s, 99,7 % of all contact force values are between x - 3s and x + 3 s. The values x + 3 s and x - 3 s arc the virtual limits of the rn:nge of dynamic cmdru:t forces. Therefore, the values obtained from the tmrn of mean values and standard deviation determine the total loading of the system components and their wear. The still acceptable minimum of the sum is caused by the rise of the electrical contact resistance and the beginning of arcing. In the case of low standard deviation, the contact force mean value can be reduced by structural 1neasures at the pantograph, resulting in a further reduction of contact line vvear without any contact interr'/1,ptions. The standard deviations obtained under the same boundary conditions can be used to compare the contact performance of va.rious overhead contact line and pantograph designs and then to optimize the rnnning performance by adjusting design characteristics accordingly. Figure 9.30 shows the statistical evaluation of a test run with the focus on the internal forces. In Figure 9.31 the dynarn.1.c range of the internal forces, which is x ± 3 s, is depicted as a function of the running speed for different DB overhead contact line types. From this Figure the contribution of the overhead contact line design to the contact performance can be seen. \i\fith contact line H.e 250, at 250 km/h contact forces and standard deviations have been achieved which equal those of contact line type Re 200 at 200 km/h. This is the limit speed at which the latter contact li11e type is used. Further improvements of pantograph design can contribute to reduce the standard deviation of the forces as well as the aerodvnamic component of the uplift force ancL therefore also the mean contact force and the total rang<' of dynamic forces. This improves the contact performance of the pantograph accordingly. Here it is essential that the value x 3 s should not tend towards zero wlwn the running vdocit,· rises. where x is the mean value of the cont,-u-t force and s the standard deviation. Apart from the mean and minimum valiw criteria for tlw contact fotC<\s the~ 1rnni11111t11 force s becomes the parameter hY which t.lt<) local wear cau lw assc\ssccl. Since the extreme values of the dynamic forces on-m rnainly at spots with in<\gtda.rities such ,,s u1ieve11 pattern of uplift, faults dming contact wir<\ i11stallilliotts. defocts in the <·out.act. wire' and singular masses (point loads) Th<'rcfor<', th('y 111ainl_, indicate tit<' posit ion of tit<' contact. wire and l Ii<' d<·, ia( ions frolll Llw sp<'rified position rM.lwr tkw t lie ( lt<·ordical bC'ltaviour or th<· ov<·tlt<',1<] cont ,1ct linC' d<'sigtt. Singular <':\.lr<'JIH' vahws or t Ii<·<
9 Interaction of pantographs and overhead contact lines
478
Dynamic contact force NEITECH · RE160 u . RE160 mod Section: 4
Deutsche Bahn AG Versuchszentrum 3 Munchen ZTV 314
Annex Order No . : 050599
Record No: 1874 Date: 5 . 07.1996 Line: STEINACH . OBERDACHSTETTEN Pantograph: 555 87 Collector strip: serial Collector strip: trapecoidal Height of carbon strip: 20mm Lok BR: 120 004 Arrangement of pantographs: _ <__ .> Air buffle: serial Measurement alternative: serial R e s u I t s: Fml= 70 N (Collector strip 1) Fm2= 65 N (Collector strip 2) Fl/F2= 1,05 ( ,95)
Static force Max force Min force Mean value Standard duration
Running speed: 132 km/h Line 5321 Stationing: Cesription of line
Fstat .. Fmax. Fmin ... Fm s
120 191 82 133 : 17,1
N N N N N
start at kro ... : 75.100 Curve
F[N] Q)
u
0
LL
200 150 100 50 0
100
200
300
400
500
600
700
800
900
Distance [m]
N
200
- - - - Re 160 -·--- Re 200 - - - Re 250
J
(
1000
Figure 9.30: Record of a contact force measuring run
x ± 3 s) = f(v)
SBS 65
/
,,'
extrapolated
/
'
/ /
100
/
-<-x
- - -
---~·- - - -=--:::_--------- -.... _ 0
150 V
200 -----
km/h
250
Figure 9.31: Dynamic range of contact forces of DB overhead contact line designs d<~pending on the running speed
9.4 Measurements and_test,s ____________ -·--· ·····---·····-··----
479
statistically defined range of dynamic forces. They can be identified as local faults in the overhead contact line. Evaluation of the recordings from regularly scheduled rnaintenance test runs on the overhead contact line netv\'Ork focuses on locating such faults. The faults in the overhead contact line are assessed and located by checking the analogue cont.a.ct force records which are available in the form of a graphical printout or a protocol (see Figure 9.30). The evaluated documents containing information on fault locations found can be forwarded to maintenance departments immediately after the test runs so corrective measures can be initiated. The evaluation of recorded measurements, including faults, has led to the following cone! usions: Any clearly pronounced discontinuity in the dynamic contact force record, as indicated by a contact force peak with an amplitude greater than 1,8 times the mean value, can always be clearly related to a particular cause. Increased contact wire ,vear is observed at every location of a fault, which occurs even at relatively low running speeds. In many cases, the cause of the fault is poor adjustment of the overhead contact line during installation. Corrective measures can be defined by checking the contact line adjustment. Other reasons may be local mass accumulations, faulty o,·erlapping sections and faulty contact line installation over points.
9.4.3
Measurement of the overhead contact line position and the thickness of the contact wire
The correct positwn of the overhead contact line as designed relative to the track is very important in view of running performance and operational security. An optical contact wire position measur·ing system is used for checking the wire position before acceptance of newly installed overhead contact lines. The system is also used for checking existing installations and operates without any contact (Figure 9.32). This measuring procedure records the contact wire position ·with a resolution of 1 mm related to the track position by means of four high-resolution diode line cameras (6000 or 8192 pixel) and a specifically designed evaluation computer. The measuring intervals are less than 3,2 ms. The system uses active lighting of the contact wire and can be adopted under virtually all lighting conditions. The use of four carneras achieves a high degree of redundancy. The cameras are arranged on a base frame with high torsional stiffness. The fra.me may be installed on everv kind of vehicle. In addition, sensors for measming and correction of the vehzde sway an~ arranged in between the car bodv and the axle bearing. The data recorded with this system is evaluated online and logged digitally as well as output graphicalh on a <·ornp11ter screen or a printer. Figure 9.:3:3 sltm\s a t:vpical printout of· the results. In addition Lo Lil<' patt.nn of tlw <·ontact wire position. ill \erti( al and t.ransw~rse direction, various se('o11dmv inforniat.ioll call lw displav<'d. for <'.'G\l11pl<' tlu~ line kilometres,
9 Interact.ion of pantographs and overhead contact lines
480 _ _ _ _ __
Z'Z
max Height
min Height
6500
mm
Contact wire '-J.
4950
I'
I I I
',
I
Camera 1 / Height
of roof
1/ / . _.,,,.
-·3500
-1000 L----11---~Measurement of distance -450
Figure 9.32: Measuring principle for recording the contact wire position
the location of poles, the location of droppers, the contact wire gradients, as well as the printouts from measurement systems for the contact forces, the uplift and the elasticity. The dropper and pole locations are identified and recorded automatically. The specified adjustment position of an overhead contact line is recorded during acceptance procedures of newly erected contact line installations and after re-adjusting existing installations. It would be useful to measure in every case the deviation, from the specified position. But for this purpose, the evaluation system would initially have to be provided with the entire contact wire position data, which would take considerable effort. A simple and practical solution consists of a graphical presentation of the vertical and lateral position relative to the track. In this kind of recording, deviations from the specified position can quickly and easily be identified. The compliance of the stagger with the specified limits can be checked at the same time. As contact force measurements have shown, sudden and large force variations are often caused by discontinviities zn the overhead contact line position. Also, for these aspects it is sufficient to inspect visually the contact force graphical records of the line section tested. Computer systems can also be used to detect and display automatically any abnormal sections recorded in the course of the test runs. By using a measuring device, it is also possible to monitor the dynamic behaviour of the contact hne immediately behind the contact point with the pantograph. If the initial position of the contact wire is known from proceeding runs, the dynamic uplift position of the ccmtcv·L line can be determined at any location by means of an evaluation computer. In principle, the syst<'.lll to tnonitor the contact wire position can a.lso be used to measure the thickness of the um.tat{ vnre because of the adopt.ion of high-resolution cameras. For this purpose, the optical n~sol11tion of the cameras must pnmit detection of the contact wire with a precisiotl of 0.1 ItlllL B.,· evaluating the \Yidth of the contact wire mirrored 1"1m:n:in.r; surface and tli<' sides of I lw co1ttact wire. tit<'. rc)sidual tl1ickness and initial
9.4 Mcas\geme11ts and tests
481
mm
mm
53001---t-----+-----+----+-----+----+-----+----+----t------+---1 0,6 mm/N
0,2 1---1-----1-----1-----l------+-----+---'"'----------'-----+------+-----+--l 200 N
%
-0, 1 ~ ~ - - ~ - - - - ~ - - - ~ - - - ~ - - - ~ - - - ~ - - ~ - - - - - - - - 132,5km 132,0km
F'igure 9.33: Typical print of contact wire po::;ition rncasmemcnts with lateral displacement, contact wire height and contact line gradient. a) Contact wire lateral position; b) Contact. wire height; c) Elasticity; d) Contact fon:c; e) Change of contact wire gradient.
1,5
I
+
I
mm -.7
t
I I
I
7--
T
1 _ .JI • lI + I
I
Cl
•_1 I
!
I I
I II
--1
I -- I-
-j -
5 05
_J I
l
J _ L
__ _I
I
I
I
.L __I_ J
L.
I
I
I
I
o~~~~~_J
3
5
I
__
I
el! ltl.fl@i+I
L0 _1_+ J ± Li_l. L
el Cl)
I
I I I , - i- -1- -1·
I+ I
lolol I I I - I
I I
J.
I_
_I
I
I
L .
I
I
I
I
I
I
L.. I
I
.1
L
I
I
I
.L
I I I l l __ ! __L 7 9
I
I
i- - I -
!
I
I
I -
_, __..
11
Number of span - - -
13
F'igure 9.34: Curnparison of optically 111· hand.
<·mi Lad
+
111c;1s11n·1tt<'td;s
•
n1cas11t<'1tH'1tts
by ltand with optical
system
482
9 Interaction of pantographs and overhead contact lines
diameter of the contact wire can be determined automatically. This is done by using the data from the four cameras and simultaneously calculating the contact wire position relative to the cameras. This enables continuous monitoring of the contact wire wear over distances of several centimetres, while measuring the contact wire position. This approach will allow detection of premature wear of the contact wire at critical spots and may initiate corresponding maintenance and adjustment procedures to extend the contact line life cycle. Figure 9.34 shows a comparison of contact line thickness measurements by hand and by the optical detection system.
9.4.4
Assessment of dynamic characteristics of pantographs
An oscillation test stand can be used to analyse and assess the dynamic characteristics of pantographs. For this purpose, the pantographs are connected to a mechanical shaker via the collector strips and subjected to vibrations. Relevant parameters such as forces, accelerations and displacement are monitored by the measuring technology and then evaluated. Measurement of frequency response To determine the pantograph's vibration performance in all degrees of freedom and without any undue reactions, a coupling as loose as possible between the vibration exciter and the collector strips of the pantograph is necessary during a frequency response analysis. From the exciter periodical or stochastic excitations of sufficient amplitude and dynamics frequency range of excitation approximately 0,1 to 70 Hz is transmitted to the pantograph. A frequency response analyser is used to determine the follo\ving characteristics, depending on the equipment of pantograph and force excitation system with measuring devices: the dynamic apparent mass graphs (an example is shown in Figure 9.11) the mechanical impedance, the transfer function of disturbances, the transfer function of contact force recording systems. These quantities can be obtained as a relation of two measured quantities related to the frequency and presented by amplitude and phase response functions. From the pattern of the functions, information on the dynamic performance and the operating quality of a pantograph can be deduced. To assess the dynamic characteristics of pantographs, the presentation of the dynamic apparent mass representing the relationship between the input force (contact force) and the sum of the resulting collector strip oscillations has proven to be informative. A pantograph, whose pattern of apparent mass shows only a few weakly outstanding natural vibration modes as well as a low level of apparent mass in total, will also be characterized by a favourable running performance. Similar conclusions can be deduced from the so-called disturbance transfer function of a pantograph. The disturha11c
9.4 Measurements and tests
-----------------------------'4~8~3
contact force to the amplitude of excitation of a contact line model (mass-springdamper system) which is coupled to the pantograph. Figure 9.10 shows an example. By means of frequency response analysis, dynamic running characteristics of pantographs can be studied on the test stand without costly running tests on lines and measures to improve the pantograph dynamics can be decided upon. Measurements and analysis of frequency responses yield additional important data for the establishment and validation of simulation models which describe the dynamic behaviour of pantographs in a mathematical format. These allow numerical studies of the interaction between the pantographs and contact lines in connection with simulation models for the overhead contact line equipment (see clause 9.3). Structural analysis By using stroboscope lights, simple optical structural analysis can be carried out on vibration test stands. Short-period, intermittent lighting of individual pantograph parts enables the vibration modes of components to be monitored. From the formation of vibration nodes and antinodes at which fatigue failures may occur under extreme conditions of usage, conclusions on the material stressing during operation can be obtained. Modelling of line running During frequency response analysis, periodical or purely stochastic excitation signals are transmitted to the pantograph. An assessment of the motion pattern and mechanical stresses occurring during real operation is possible to a limited extent only. By simulating line running in a test stand, it is possible to produce realistic motion patterns for a pantograph interacting with a contact line of particular characteristics. Effects to be considered include changes in the contact wire height, its lateral position ( contact wire stagger) and highly dynamic motion effects imposed on the pantograph by interference excitation using simplified contact line models. The evaluation of relevant parameters such as internal force and contact force permits a very precise assessment of the running performances of pantographs with various overhead contact line designs. Figure 9.35 shows schematically, the structure of a test stand established at Deutsche Balm AG for carrying out sirnulated test runs on lines. A gantry (axis A3) is used to simulate gradual changes of the contact wire position occurring for example, at contact wire lowerings or rises. A moveable sledge arranged horizontally on the gautr)' (axis A2) is used for simulating the contact wire stagger. An actuator arranged at the horizontal sledge and acting in the vertical direction, (axis Al) applies high-frequency excitation signals to the pantograph through a massspring-damper system arranged in between and used for the simplified modelling of the contact line, The signals for excitation along the different axes are deduced from data recorded on test runs carried out on real lines or from computer simulations taking into account the concac-t line ruodeL
-184
-----~-------
9 Interaction of pantographs and overhead contact lines
Figure 9.35: Schematic presentation of the structure of a test stand to carry out simulated test runs on lines
9.4.5
Measurement of contact wire uplift and dynamic contact line elasticity
9.4.5.1
Stationary measurement of contact wire uplift
The contact wire uplift can be determined either by stationary measuring equipment at a contact line support or by mobile measuring equipment installed on a vehicle. To monitor the development of the dynamic uplift with time at a support, stationary upl~ft measuring devices are used. This is necessary for acceptance or determination of the maximum permitted speed of ne,Y vehicles or pantographs, in conjunction ·with the overhead contact line design so as not to exceed the maximum permissible uplift. the stationary monitoring of pantographs in commercial operation. \i\Thile initially, for short periods, the uplift will be measured when carrying out acceptance running, eventually a fully automatic operating installation must be installed at several locations within the network. Using a potentiometer connected to the steady arm with a pre-tensioned r,lpe, the uplift movernent is monitored while stationary at a support. The isolation of potentials is achieved ,vith an insulating section within the rope (Figure 9.36). The signal is transferred without anv potential h_y means of an optical coupler to the measurement amplifier, directly con11<:ctecl to a PC. Since the uplift is a function of the running speed, this is regist.en'd autoumtica.lly by means of two coutacts at the rails. The recorded data is trausf<'n<'d h,· uH~ans of Gl'vIS radio. This dC',·ic:e has the advantage of simply monitoring the displace1t1<:11t of the contact ,virc' at a support with tirne. Figur<~ 9.37 shows tlw v1'.·t/1rnl 111.0·1wmcnt of a 1:mdact. w1·1 e at a support ,,·lwn a train, wliiclt has two p;-rnl.ogrnplt:, sp;H'<'d :ti"() 111 ;1pmt, is p;1ssi11g. TIH' l<~adi11g pa11tograph
9.4J\1Ieasm~emeuts and tests
485
100
-272m
.
F
/120001\
mm
10 carriages ___
locomotive 2
-
~-
_ 103003
locomotive 1
-
-----
,_ -
]
.
II
.,,
11111
0 .
contact wire 0
Figure 9.36: Statio11ary recording device for co11tact wire uplift
4
8
'
.
l
Al
1/IIU r'\(\I\,
y~v
12 16 20 24 Time---
' I
J
kkn 1-tdd ' U!.
28
,
32 s 36
Figure 9.37: Cont.act wire uplift. a.s a function of time, train with two pantographs travelling at a speed of v = 270 km/h
lifts the contact wire approximately 80 mm. The trailing pantograph then runs along a contact wire oscillating at one of the natural frequencies of the overhead contact line equipment. However, the resulting uplift is almost the same as that caused by the leading pantograph. After the passage of the two pantographs, the contact line oscillates at an amplitude of ±20 mm with relatively low damping. In view of the pantograph diagnostics during commercial operation, the uplift during a pantograph passage enables conclusions to be drawn on the condition of the pantogr,1,ph. This is possible since maximum uplift is proportional to the contact force of the pantograph a.t the location of the support. The contact force is formed by the following components: Fco11tacl -
Fstatic
+ l~1ernclynarnic + Fdy11arnic
(9. 79)
where .f,tatic is the contact force exerted by the pneumatic drive of the pantograph at speed zero, F,tcioclynarnic denotes the increase in contact force due to aerodynamic effects and Fc1ynarnic: represents the componellt of the contact force due to the intentction between pantograph and overhead contact line. For a particular train running speed, any marked increase or decrease registered rn uplift indicates disturbances or defects at the pantograph. These can be caused by: a too high or too lm,v ae:rodynmnic fon:e F,terndynamic clue to: incorrectly adjusted or damaged wind baflies; - obliquely worn contact strips caused for example b)' an inclined pantograph head; a too high or too low static rout.ad, forn' .f~t.atic due to: iHco1rcct.ly adjusted static contact force; a larg<' d1aug<~ iu th<' rnntact st.rip rnass, CcWS<~d by a collector strip, for exa111ple worn out IH'vond acccpt.ahk limits; n too higl1 01 too lm\ dvu,1111ic co11t.ac-t fore<' co11qHHl<'11t rh11;-unic due to defect.iv<'. 1u<~cl1anical parts 1-1t. !.11<' pnutogrnpl1, for <'xa1npl<' a ddl'ctiv<' damp<'r; 1
9 Interact.ion of pantographs and overhead contact lines _________________ _
486
~::__
1 0 - - - 1 - - ~ I - - - I- - ~ I - - - , I I I I
cm
s
-,-7--:-
r--:--: -:--T-- +-
t
6
§-
4
--- :----: I I
--: I
I
2
---~--
-~
~-
"-=
---~--I
I
~
I
-~I
--~ ct
I
I
--+-~-I
ct
I
O~ - ~ - - 2 - ~ - 3 - ~ - 4 - ~ - 5 ~ Test run No. - - - -
Figure 9.38: Comparison of the results of mobile and stationary contact wire uplift measurements (five test runs, one stationary measuring location). + stationary measurements • mobile measurements
- a large change in the contact strip mass, for example caused by a collector strip worn out beyond acceptable limits. This shows that the observation of uplift forms an important tool for automatic pantograph diagnostics which can effectively monitor many defects. However, this supervision will not identify the actual reasons for the defects.
9.4.5.2
Mobile measurement of the contact wire uplift
To measure the contact wire uplift while mobile from a vehicle, a measuring device for .::ontact free recording of contact wire position according to section 9.4.3 is necessary. A.t first, the initial position of the contact wire is recorded on a run with a train liauled by a diesel engine without a raised pantograph on the train. Then, during an :i,dditional test run with an electric traction unit and a pantograph raised, the contact wire position is measured again. The optical measuring system is installed directly at the pantograph . By subtraction of the registered contact wire heights over the two measuring runs, the ~ontact wire uplift can be determined. For this purpose, equipment is necessary for :i, very precise measurement of the kilometre position and the running distance. Only ,vith a precise correlation of the two runs a subtraction of the registered contact wire 1eights can give an accurate value. fhe results of the mobile contact wire uplift measurements were compared to the data )btained from a stationary measuring installation, as shown in Figure 9.38.
J.4.5.3
Measurement of the dynamic elasticity of the overhead contact line
\,feasurement of the overhead contact line elasticity is possible by a supplement to ,he measuring installation described in section 9.4.5.2. In addition to the contact free neasurement of the contact wire position, according to section 9.4.3 an installation for neasuring the contact force as per section 94.2 is necessary. The measuring process is ,imilar to that described in section 9.4.5.2. In addition to the contact wire uplift, the ·ontact force is recorded, synchronized with the running distance. By dividing the uplift wd the contact force, the dynamic contact line elasticity is obtained (Figure 9.33).
~~ __Effect,
of the design parameters
9.5
Effect of the design parameters
9.5.1
487
Introduction
A large number of design parameters affects the dynamic behaviour of an overhead contact line supplying energy to trains, especially to those trains travelling at high speeds. Theoretical studies of the interaction of overhead contact lines and pantographs (clause 9.2) have led to the definition of a series of criteria. which can also be used to assess the effects of the individual parameters. Apart from this. measurement methods for examining the interaction of the two part-systems are known and enable empirical studies of the effect of the individual parameters on the moving contact quality [9.8, 9.30] (see clause 9.4). The conclusions drawn from these studies are used as a basis for structural and mechanical design work for electric raihrny traction energy transfer systems using contact lines.
9.5.2
Criteria for overhead contact line installation designs
9.5.2.1
Elasticity and uplift
The uplift of an overhead contact line must be kept to a minimum in order to achieve good contact quality. In addition, the mechanical design of the supports limits the possible vertical motion at these points. At low and medium speeds, i.e. at speeds of up to approximately 50 % of the wave propagation speed. the uplift is proportional to the elasticity of the overhead contact line equipment and the contact force exerted by the pantograph. To maintain the running contact quality at increasing speeds, the contact force must be increased as well, which means that the elasticity has to be kept as low as possible to limit the resulting uplift. The elasticity of an overhead contact line can be calculated \Yith sufficient accuracy using a mathematical model based on the finite-element method (FEM). Figure 9.39 shows the calculated elasticity graph of DB's m·erhead contact line design Re 250. Reference [9.17] contains a description of a suitable calculation method. As a comparison, the values shown for various standard DB overhead contact lines in Figure 9.40 were obtained by an extensive series of measurements. The elasticity at the rniddle of a span can be calculated using the equation e
l / [k ·(Hew+ HeA)]
in mm/.\/,
(9.80)
where: l longitudinal spau in m, Hew contact wire teusile force in kN, He:/\ catenary vvire tmsile force in kN, k numeric factor ranging between 3,5 and 1,0 as described in r<'fcrenc-e [0.:n]. For catenan systems ,,ithcrnt a stitch wire, k for U1osc\ with a stitch wir<' /.: -- '.\/> .
= '1,0,
-188
_______________
~::::__
9 Interaction _of pantographs and overhead contact lines
65m
0,60 mm/N
!
'-
0,50
c 2 (/)
-- ------, r--...
0,55
0,45 0,40
~
"--..... /
/
./-------
/
~
"--..... /
/
63 0,35 0,30
Figure 9.39: Elasticity of overhead contact line design Re 250, calculated using FEM
~ff
P"'hoff
support span mid-point support 1,2 . - - - - - - - . - - - - - - - - - : : ; , . . - l - c ; : : - - - - - - - - , - - - - - - - , mm/N
Re 200 Re 250 _j Re 100 0,4L_---======-------_j_---------=~======-__J
Figure 9.40: Elasticity of standard overhead contact line designs Re 100, Re 160, Re 200 and Re 250 used by the Deutsche Balm AG (measured values)
0,9 + - - - - + - - - " , ~ - - - - + - - - - - - + - - - - - - - - 1 mm/N
CuAg AC-120, Bz II 70 / (measureu values)
Cl)
c
0,6
1
63u5
0,5
-i-~gart--------t--~~-
:~
-~~~';;;f;';;;";;\;9--~""'::-..::="'f-~:s.:;z:~z--j
N
0,4
Cl) o::_,__ _ _ __
0,3 20
25
Tensile forces (Hew +Hefl )
30
kN
35
Figure 9.41: Elasticity in the middle of a span, overhead contact lines with and without stitch wires, plotted as a function of the tensile forces. A comparison of measured values with values estimated by approxiwation calculation, span length G5 u1
9.5 Effect of the design parameters
489 ------ ------------- - - - - - - - - - - - - - - =
Table 9.2: Specifications for overhead contact line elasticity and elasticity uniformity Train speed km/h up to up to up to up to above
100 160 200 280 280
Elasticity
Degree of elasticity uniformity
mm/N
%
1,20 1,20 1,10 0,60 0,40
50 30 20 10 8
u
a
u
a
u
a
u
a
u
a
100 mm
1,0 0.
::::i
o~~~-~.,__~~-~~~~~~-~~---""~-"'-"-'---'----L-~~
Contact line design Re 200
Re200
Re 200
Mean contact force 100 N
110 N
115 N
Re 250 110 N
Re 250 120 N
Speed
220 km/h
230 km/h
250 km/h
280 km/h
200 km/h
IZZZ2J theoretical static values u
push-off support
c:::=::J Measured values a
pull-off support
Figure 9.42: Comparison of theoretical static uplift values and measured dynamic uplift values
Figure 9.41 shows that equation (9.80) gives a reliable and acceptable approximation of the elasticity of an overhead contact line. The elasticity at the supports depends on the structure of the overhead contact line equipment. At the supports, contact lines without stitch wires only achieve elasticity of 30 % to 50 % of the mid-span values. However, by adding suitable stitch wire arrangements, the elasticity at the supports can be increased to approximately 90 % of the mid-span values (Figure 9.41). As train speeds increase, the umformity of the elasticity becomes more and more important. The degree of elasticity uniforrnity 'U,
= 100 · (emax
emin) / (fmax
+ emin)
in%,
(9.81)
in which Cmax and ernin are the maxirrnt and minima of the elasticity, characterizes the elasticity variation along a span. Unifonnity values of less than 10 % are desirable for overhead contact lines for high-speed trafli.c and can be achieved (c.f. Table 9.2). Tlic rrwan value of the contact force exerted by the pantograph and _the elasticity of (!}(' c:ont.;-,cC litt(' drt<·rrnitie tl1<~ rout.act. wire nplifL As train speeds increase, a dynffmic
9 Interaction of pantographs and overhead contact lines
490
uplift component is superimposed on this static value. The dynamic component, which increases sharply with speed, is a function of the dynamic characteristics of the overhead contact line. Figure 9.42, taken from reference [9. 7], shows the development of the dynamic uplift value compared to the calculated static values as a function of the train speed. The calculated static values are the product of the mean contact force exerted by the pantograph and the elasticity of the overhead contact line. For an overhead contact line installation designed for 200 km/h (Re 200), the measured dynamic uplift values only exceed the calculated values at speeds of 230 km/h and above. At higher speeds, the sharp increase in the dynamic component is noticeable.
9.5.2.2
Dynamic criteria
A series of dynamic criteria, which can be used to formulate the specifications for design of overhead contact lines with certain desired characteristics, was derived in section 9.2. The wave propagation speed of transversal waves along the contact wire, as described by equation (9.6), is one of the fundamental dynamic design criteria. This, in relation to the train speed, permits the Doppler factor to be derived using (9.56). The Doppler factor approaches zero as the train speed approaches the wave propagation speed of mechanical impulses along the contact wire. The reflection coefficient, according to (9.61) is another parameter which determines the dynamic behaviour of overhead contact line equipment. It is only a function of the overhead contact line design data, i.e. it does not depend on the train speed. As explained in reference [9.8], the ratio of the reflection coefficient to the Doppler factor is called the amplification coefficient (c.f. equation (9.59)). This coefficient is also a function of the train speed. The effect of the dynamic criteria on the behaviour of an overhead contact line, can be verified by measurements. When preparations for high speed trial runs were in progress in 1988 [9.1] one of the decisive issues was whether an overhead contact line design of type Re 250 would permit speeds in the region of 400 km/h. In the course of trials carried out by the SNCF in 1981, the dynamic uplift of the overhead contact line limited the maximum speed to 380 km/h [9.32]. The uplift reached values of around 200 mm. In test runs using the ICE/V test train in November 1986 on a section of the HanoverWiirzburg line, the maximum uplift measured at a support was 105 mm whereby the maximum speed at the point where the measurement was taken was 310 km/h. The measured uplift increased more than proportionally with the train speed (Figure 9.43). Since the mean pantograph contact force was constant at 120 N, the dynamic effects must have been increasing the uplift considerably. In 1981, the French railways SNCF used a,n experimental oYerhead contact line with a contact wire cross-section of 150 mm 2 ,1,nd a tensile force of 20 kN, i.e. a stress of 133 N /mm 2 [9.32], for which a wave propagation speed of 4-10 km/h can be deduced. The uplift values measured and calculated for this overhead contact line are plotteti as a function of the train speed in Figure 9.43. According to reference [9.32] the rneasured values obtained by the SNCF at 300 km/h are lower than those monitored for the Re 2-30 design. At 400 km/h, uplift va,l ues of a.pproxirnately :300 mm are to br expected
.I
9:5 Effect of the design parameters
491
300 - , - - - - - - - - - - - - - - - - - - , . - - - - , ~ - - - , Re 250, CuAg AC-120, H= 15 kN £ 125 N/mm SNCF, Cu AC-150, H = 20 kN ~ 133 N/mm 2 : mm Re 250 V, CuAg AC-120, H 21 kN ~ 175 N/m,ti 2 I
2501-f----f-------i'-----+----.-'-1-1~---j
t
alues, pen line 0 -t-11-----+----t-----+----t-------i 200 250 300 350 400 km/h 450 Train speed v _ _ _ ____,__
Figure 9.43: Vertical uplift of overhead contact lines as a function of the train speed [9 .1]
with the SNCF overhead contact line. Since the wave propagation speed of the Re 250 design is 426 km/h and therefore lower than that of the SNCF's experimental overhead contact line system, the dynamic effects would be even greater. The uplift in a Re 250 without any modifications would be considerably greater than 300 mm at a train speed of 400 km/h. Such high values cannot be permitted because the uplift range of a standard Re 250 design is limited to 200 mm by structural parameters. Thus it would not have been possible to achieve a train speed of 400 km/h using a standard Re 250 overhead contact line. The same conclusions can be drawn by studying the Doppler factor and the amplification coefficient plotted as a function of speed as shown in Figure 9.7. The relevant data are summarized in Table 9.3. The experimental SNCF contact line reached the maximum speed where supply of power to the train was interrupted at a Doppler factor of 0,073 and an amplification coefficient of 5,0. To reduce the clyncirnic uplift, the Doppler factor must be increased, and this can only be achieved by increasing the wave propagation speed of the contact wire. According to equation (9.6), this can be achieved by increasing the contact ·wire stress but not by increasing the tensile force acting on the wire while increasing the cross-sectional area and retaining the same stress. According to equation (9.5G), to keep the Doppler factor at values equal to or above 0,1 at a tra.in speed of 400 km/h, the wave propagation speed must be approximately 490 km/h. As per (9.6), this would correspond to a tensile force of approx. 20 kN acting on the 120 nun 2 contact ,-vire, or a stress of 167 N /mm 2 . To provide tli(' best possible conditions for the trial runs, a fore(~ of 21 kN ,vas applied t.o tit(' rn11l,,1ct \\'in~ [~U] This incn~ascd t.hc wave propagatio11 sp<'cd Lo G04 km/h, the
492
9 Interaction of pantographs and overhead contact lines
- - - - - - - - - - - ----~---·----------
Table 9.3: Dynamic characteristics of overhead contact lines used for high-speed test runs Units
SNCF 1981
Cu AC-150 Contact wire 20 kN Tensile force Bz II 65 Catenary wire 14 kN Tensile force 440 Wave propagation speed km/h 0,363 Reflection coefficient 0,53 Elasticity at middle of span rnm/N 380 Maximum speed km/h Doppler factor 0,275 at 250 km/h at 450 km/h 0,073 at maximum speed Amplification coefficient 1,3 at 250 km/h at 450 km/h 5,0 at maximum speed
Re 250 DB 1988
Re 330 DB
SNCF 1991
CuAg AC-120 CuMg AC-120 CuCd AC-150 21 27 33 Bz II 120 Bz II 70 Bz II 70 21 15 15 504 572 560 0,469 0,392 0,314 0,44 0,39 0,33 407 515 0,337 0,057 0,106
0,392 0,120
1,2 6,9 3,7
1,2 3,9
-
-
0,383 0,109 0,042 0,8 2,9 7,5
reflection coefficient was 0,392 and at a train speed of 400 km/h, the amplification coefficient was 3,4 (c.f. Table 9.3). In Figure 9. 7, a considerable improvement of the characteristics because of this increase in the contact wire stress is visible. Particularly at speeds above 350 km/h, considerably reduced overhead contact line uplift was to be expected (Figure 9.43). These expectations were fully confirmed by the high-speed trial runs. The 400 km/h barrier was broken for the first time ever and a top speed of cl:07 km/h achieved. The overhead contact line uplift values measured are plotted in Figure 9.43. The maximum value was roughly 140 mm. The calculated predictions concerning the uplift were confirmed. This example illustrates the effect of the dynamic criteria on the contact characteristics.
9.5.3
Overhead contact line design parameters
9.5.3.1
Cross-sectional areas and tensile stress
The cross-sectional areas of the contact wire and the catenary wire can have a crucial effect on the behaviour of an overhead contact line when a pantograph travels along it at high speeds. According to equation (9.80), the requirement that overhead contact lines for high-speed trains must exhibit a low and uniforrn elasticity, leads to a demand for high tensile forces on the contact ,vire and the catenary wire. This could be achieved by using large cross-sectional areas and corresponding stresses. The need to be able to handle and install contact wires limits the maximum clirnensions of the contact wire. As a result, contact wire cross-sections are limited to a maximum l)f 150 111111 2 , whereby even this cross section incurs a great risk of localized clefocts (bends etc.) being created during the installation work, subsequently leading to rapid wear at the respective locations.
'I
9.5 Effect.of the design parameters
493
tensile force 15 kN 200 N 100
0tensile force 21 kN 200 N 100
0
50 N
z 0
0)
Figure 9.44: Contact force graphs of contact wires subject to tensile forces of 15 kN and 21 kN. contact wire CuAg AC .. 120, overhead contact line design Re 250.
If the tensile stress is kept constant, increasing contact and catenary wire cross-sections leads to a linear reduction of the elasticity. For this reason, contact wires and catenary wires with as large a cross-section as possible are desirable from the perspective of aiming for very low elasticity. However, the investment increases in proportion to the cross-section, and for commercial reasons, investment must be kept as low as possible. In the course of development work on the contact line type Re 250, the DB also tested overhead contact lines using contact wires CuAg AC-100 and CuAg AC-120 along the Neubeckum-Giitersloh trial line. Both wires were subjected to a tensile stress of 125 N/mm2, in view of train speeds of up to 280 km/h (9.33]. The wire with the larger cross-sect.ion led to lower standard deviations in the contact forces, i. e. was better from the dynamic aspect. As can be deduced from (9.6), equal wire stresses cause equal wave propagation speeds along the wire and thus also equal Doppler factors. For this reason, increasing the cross-sections while maintaining the same stress would not contribute to any progress vvith respect to the suitability of an overhead contact line for operation
at near-rna.1:imum speeds. Assuming equal cross-sections, increasing the stress will reduce the elasticity of the overhead conta,ct line (9.80) while at the same time increasing the wave propagation speed along the wire, as demonstrated in (9.6). Equation (9.Gl) shows that increasing the contact wire stress will also affect the reflection coefficient. Increasing the contact wire stress improves all the significant parameters of an overhead contact line, as well as the dynarn.'ic performance. Figure 9A-l shows the contact force graphs recorded when travelling along an overhead contact line of standard design Re 250 with contact wire forces of 15 kN and 21 kN, respectively. at a speed of 280 km/h. The dynamic bandwidth is reduced considerably and the conrnct force peaks are lower on that wire subject to the higher tensile force. Figure 9A.j shows the observed standard deviations for th<'S<' tensile forces of 15 kN and 21 k..\ as fonctions of the train speed. The standard deviation achieved with the tighter wire is :3 _\ lower on average, this being equivalent Lo a 15 % decrease at traiu speeds of 250 km/h. Therefore, increasing the stress iu the contact wire is oue of the most suitahl(' 1uc:asurcs for adapting an ovct!wad cont.an li1w for hiyh-sJJceri train traffic. Acrnrdi11g to equation (~).Gl), the stn~ss in th<' caLPt1,1n \\it(' \\ill also affect. the reflec-
9 ?::::_:___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Interactionofpantographs and overhead contact lines
25 N
1
tensile force 15 kN 20
§ §
> (I)
u u uC
15
'°
tensile force 21 kN
ro
u5 10 5 200
250 Train speed v
km/h
300
Figure 9.45: Standard deviation of the contact force plotted against running speed, contact wires subject to tensile forces of 15 kN and 21 kN, contact wire CuAg AC-120, overhead contact line design Re 250.
Table 9.4: Tolerances of contact wire hight, stagger and gradient of DB overhead contact line designs Re 200 and Re 250 (excerpt from specification 3 Ebs 02.05.19) units Re200 Re250 Contact wire height mm ±100 ±30 Support to support mm not defined 20 Dropper to dropper mm 20 10 Contact wire stagger mm ±30 ±30 Gradient 1 1:1000 1:3000
tion coefficient. To obtain a low amplification coefficient, a reduction of the catenary ,vire stress is desirable. With the objective of achieving a low elasticity, the DB standard overhead contact line Re 250 was originally designed to operate with a catenary wire tensile force of 19 kN, which corresponds to a stress of roughly 290 N/mm 2 . Reducing the stress to approximately 210 N /mm 2 lowered the reflection coefficient from approximately 0,46 to 0,42. For a train speed of 280 km/h, the amplification coefficient was reduced from 2,2 to 2,0 i.e. by 10 %. For this reason, the tensile force on the catenary wire was reduced to 14 kN in some O\·erhead contact line sections. The dynamic contact forces did not differ significantly from those observed in the sections with a tensile force of 19 k:-J. As a result, other new overhead contact line stretches of the DB are being built with both the contact \Yire and the catenary each tensioned to 15 kN. Table 9.4 also includes the specifications of the standa:rd overhead contact hne design Re 330 [9.7]. This design was chosen with the objective of achie,·ing favourable performance characteristics at speeds above 300 km/h.
9.5.3.2
Span lengths and system height
The span length affects the system elasticity ns <~xpressc•d in equation (9.80), the elasticity at the mid-point of the span being propmtiotud to 111<' spa.ll l<'ngtlL Reducing
.i
9.5 Effect of the design parameters
495
200
l (I)
a) span lengt11 44 m
N
150
100
~
E
t3
<1l
c0
50
0
0 200 b) span length 65 m
l (I)
150
100
u
2 t3 <1l
c0
50
0
0 0
300 Distance travelled - - -
600
m
900
F'igure 9.46: Dynamic contact forces as a function of the span length; system height 1,80 m, overhead contact line Re 250.
the span lengths will also reduce the elasticity of the overhead contact line system. For high speeds, shorter spans are preferable but the larger number of poles and foundations required imply higher installation investments. The demand that the span be as long as possible for economic reasons without leading to negative running contact characteristics, poses an optimization problem. The design of overhead contact lines Re250 [9.30, 9.34, 9.35] and Re330 [9.7] with a maximum span length of 65 m instead of the 80 m used in other standard DB overhead contact line designs, has led to a reduction of the elasticity by roughly 20 %. To halve the elasticity in comparison to that of the standard designs Re 160 and Re 200, it would not have been sufficient to just increase the contact wire and catenary wire cross-sections and the tensile stresses in these components [9.6]. Actual installations have tension lengths with varying span lengths. Figure 9A6 shows a graph of contact forces along span lengths of 44 m compared to a graph of contact forces along span lengths of 65 m under otherwise equal conditions. At a train speed of 280 km/h the standard deviation of 19 N obtained ,vith shorter spans is clearly lower than the normally observed value of roughly 22 N. Therefore, reducing span lengths and consequently lowering the contact line elasticity, contributes towards reducing dvaamic force effects. The systern height, which describes tlte distance between the catenary wire aud the contact wire at the supports, does uot occur as a parameter in any of the expressions for the characteristic properties of overhead contact lines. The system height O\ erhead contact lines in tunnel scctious of G<~rman high-speed lines is 1, 10 m and tlw span leugth is 44 m [9.36]. Figttrc 9.cl 7 shows a comparison of these \\ith equivalent t.cnsioning lc-n11lhs lrnxiug the sa11te sp,w l
-!96 - - - - - - - - - - - ------ --------
··-~-
200
-·--
9 Interaction ofpantographs an
a) syslem heighl 1,80 m
N
l (j)
150
100
0
.£ t5 cu
c0
50 -
0
0 200 b) system height 1, 10 m 150
1 100 (j)
0
2 t5
cu
c0
50
0
0 0
300 Distance travelled - - - -
600
m
900
Figure 9.47: Dynamic contact forces depending on the system height, contact line design Re 250 with system heights of 1,80 m (sections in the open) and L40 m (sections in the tunnel). span length 44
Ill.
installed on sections in the open. The increased system height appears to lead to improved dynamic characteristics. This can also be seen in the difference between the standard deviation values on the contact force diagrams for a train speed of 280 km/h, specifically a reduction from 23 to 19 N. Overhead contact lines for high-speed railways should be designed with adequate system heights that permit a minimum dropper length of 0,8 m or, better still, of 1,20 m.
9.5.3.3
Pre-sag and stitch wires
Adjusting an overhead contact line in such a ,vay that there is an initial sag (''pre-sag") at the mid-point of a span relative to the supports, is based on the assumption that if the elasticity at the span mid-point is higher than at the supports, the pantograph will lift the contact wire to a greater extent at that point. The pre-sag aids in achieving a contact locus at a constant height relative to the rail head. Tliis desired effect would only be achieved however, if the conta.ct force exerted by the pantograph were independent of the pantograph design aud train speed. As this is not the case, it is only possible to adjust tlw s_vstem for a constant-height contact locus for static uplift conditions and for a specific- contact force. The overhead contact line d<~~:igns of Re\ lGO and Re 200 still show relatively great differences between the ela.sticity ;.1 t the supports and at the span mid-points. In the course of experiments carried 011t in 19G2 [9 21]. designs with and without pre-sag were tested. For spans of l<\ngtli 80 rn . a, pr<'-saµ, of ;.1pproxinrnteh· 50 mm rcd11c-c'd rlw number of c:ontad, losses 1101.ic:<~a hi\·
•
I I
~-5 Effect of the design parameters
b) push-off support
a) pull-off support
0, 7 -t-----+-------+---l------·--t-----j mm/N
mm/N
l
(!)
0, 6 . elaslicit
3,5
;
5,0
J
o
~"'-t---=-4--=--J3· 5-8,0 9,0
o.5
-t---t---=...-C-:0,....-Cl-:;7"~-t-----J-----j
0,4 - t - - - - + - - - - - + - - · · · - - - 1 - - - - - + - - - - - l
22 Stitch wire length Ly
~
14
16 18 Stitch wire length Ly ~
20
m
22
Figure 9.48: Effect of the length and tensile force of stitch wires on the elasticity of the overhead contact line at support points, overhead contact line design Re 250, contact wire RiS 120, tensile force 15 kN, catenary wire Bz II 70, tensile force 15 kN.
Stitch wires installed at the supports increase the elasticity at these points and can therefore lead to a considerably more uniform elasticity along a tensioning length. Figure 9.48 shows the effect of the stitch wire length and tensile force on the elasticity of the catenary system at support points as determined for a DB standard overhead contact line Re 250. The elasticity at a push-off support can be made roughly equal to that at span mid-points by installing stitch wires of 18 m length. The elasticity of pulloff supports with stitch wires of this length are only slightly lower. Uniform elasticity leads to a constant static uplift and causes less vertical pantograph/ collector strip motion. The dynamic effects of stitch wires can be assessed both by mathematical simulation and empirically by test runs. Figure 9.49 shows the results obtained by contact force sfrrwlation calculations. When the high-speed Hanover-Wi.irzburg line was built, some tensioning sections were installed [9.37] without stitch wires at the supports. To compensate for the differences in system elasticity, ·which are greater in these sections, the contact wire was adjusted to obtain a pre-sag of approximately 50 mm, i.e. less than 0,1 % of the pole spacing. Figure 9.50 shows the results of contact force measurements at 265 km/h. The dynamic range of contact forces is narrower and no pronounced contact force peaks are observed at the support positions. fhe standard deviation, which is a characteristic: value for the contact quality of contact line designs, is greater for the contact line installation without stitch wires. This demonstrates the importance of sht:ch wires for superior operating characteristics of overhead contact lines at high running speeds. It is not difficult to install stitch wires accurately if adequate tools ar<' used. The additional effort required is negligible. The design and installation panrnl<'tets of the stitch wire., can be calculated by sirn:/J,lations of elast.·1,r:dy and wnlad f"mv·s .
498= - - - - - - - - - - - - - - - ___ ~-~teractim1_~)_f_pc1:11togrnphs and overhead contact llnes 140
a)
N
j
1
~
0)
E'
g
t5 co
c0
rw
~
20
u
0
b)
200 N
1 0)
E'
s t5
co
c0
0
20 0
Distance
Figure 9.49: Contact force simulation of an overhead contact line Re 250, span length 65 m. a) with stitch wires; b) without stitch wires.
a)
200 N
100 0 b)
200
Figure 9.50: Results of contact force measurements, overhead contact line design Re 250, train speed 265 km/h. a) with stitch wires b) without stitch wires.
N
100 0
9.5.3.4
Effect of adjustment accuracy
The designed contact wire positions must be achieved by the installation process within a more or less narrow tolerance range. With this iu view, the German railway DB has defined tolerance limits for its overhead contact lines to ensure running qualities. These tolerance ranges are narrower for the higher qua.lity overhead contact line designs. Table 9.8 gives an example of these values. The following parameters in particular, are important: - height d,Uferences from orw dropJ>e.·1· to tlw 1wxt, hci_r;ht; cl-i.£1'erences from, one snz1pod: to Uw ueT/,, dw:n_qe of gnuhen/; at the su71port.s, and conta.ct wire height tole1a11n!s.
9.5 Effect of the designr_ararnete,s
499
Evaluations of the results of test runs have shown that the desired contact quality is easily achieved if the installation is within specification tolerances. A pre-sag of up to 30 mm at the middle of a span has no adverse effects. Any substantial deviation from the stipulated tolerances, especially above switch points and in areas where overlaps occur, leads to noticeable contact force (~ff'ects in the form of pronounced peaks.
9.5.4
Pantograph design parameters
9.5.4.1
Introduction
The design and the characteristics of pantographs also have a considerable effect on the running quality. Running ctll unsuitable pantograph along a contact line which is suitable for high speeds per se, will not produce the desired result. Conversely, the use of a pantograph suitable for high speeds cannot increase the acceptable ma.xirnum speed of a normal overhead contact line to any great extent. Experiments carried out by the DB [9.33] have repeatedly demonstrated this for a standard overhead contact line design Re 200. Even when sophisticated pantograph designs are used, the possibilities of this contact line installation are exhausted at a speed of 200 km/h. For satisfactory energy transmission to high-speed trains, a combination of suitable overhead contact line and corresponding high-speed pantographs is essential.
9.5.4.2
Features of pantograph designs
The DB standard overhead contact line Re 250 was originally tested using a standard pantograph of type SBS 65 [9.38]. On this single-arm pantograph, both collector strips are mounted on a frame-type pan head which is spring-mounted on the upper frame by rubber elements. Its contact force is 70 N under static conditions and increases substantially with speed due to both the aerodynamic effects and contact strip vvear, as shown in Figure 9.51. Measured average contact forces were as high as 190 N 011 stretches in the open and 230 :-: in tunnels. Figure 9.51 also shows the wide d_vnarnic range. At 250 km/h, the contact force peaks exceeded 300 N and the stancliud d('viations were in the region of 26 .\I Trials have proven that a pantograph of t\pe SDS 65 is not suitable for speeds a hove 200 km/h. Not just because of its uufm ourahl<' aerodynamic characteristics bu1 also because of the high dynamic: forces ocrnrriug as the pantograph moves along the overhead contact line, these being caused b, the high unsprung masses of the frame-t\·pe pan head and the hard rubber torsion springs 011 which the pan head is mounted To maintain the previously cxperie11c('d long service life of the contact rn111po11ents, contact wire and pantographs, while enabling higher train speeds, it lwnune 11<'< ('Ssar_v to develop new pantograph desurnc; The design specifications for these new pa 11tographs were derived from the experie.nc<' gained in the rnurse of the overhead ,·ontacl li1t<' trials . The rnean contact force was no! Io exceed 120 N at a running speed of JOO krn/h. Figure 9.52 shows the diagraitts or the standard dc~via.tions for Yarious rnrnhiw1t ions of standard overhead contact Jin<' s\·sl,<~ms and pantographs and th<' targ<'I sp<'cific,1.Lious for high-speed train tnd[ic d<'1 i\!'d fro111 Llws<~ valtt<'s Th<' s/.0111/anl 1/r:l!1ul 11111 11/ t II('
50_0_ _ __
)J llll,('.lilCLI\Jll l>I pi!lll,Uf!,1<1pll:i cl.Ill! uve111eaU CUllLa.CI, Ullec,
250 - - . - - - - , - - - - - - - , - - - - - r , ~ - - - , N
35 ~ - ~ - - - ~ - - ~ - - - - - - ~ N 30 -
200 -I---,----+-----,'-
Cf)
0
U'J
1
25
C') Q)
<{
0
Cf)
2100-1-----J SBS 65
0
1;j c0
0
DSA 350 S
x-3s
0 -t----+-----+-----l-------1 100 150 250 km/h 300 200 Running speed - - - - -
Figure 9.51: Contact forces of the pantograph types SBS 65 and DSA 350 S depending on the train speed, overhead contact line Re 250. x mean value, s standard deviation of contact force.
ICEN
0-
150
200
250
300 km/h
350
Running speed
Figure 9.52: Standard deviation of the contact force as a function of the train speed, measured for pantograph types SBS 65, WBL 85, SSS 87 and DSA 350.
I
.I Figure 9.53: Pantograph DSA 350 S with independently sprung collector strips.
dynamic forces must be just 20 %1 of t.lw mean value, i.e. 24 N . .-\ further requirement is that the dynamic load should he ()\'e11ly distributed over both collector strips in order to ensure an arc-free slidiug rn11t act. These specifications were fulfill<·d hv several new pantograph designs [9.10, 9 . 35, 9.37]. The test runs demonstrat<'d thM pa.ntograph performances at high speeds a.re determined by the design of the pan head and the collector strips. Therefore, the h<~ad mass and head clamping W<)r<' red1H:<'d in cornparison to earlier models . .-\t the same time, the pantograph mass as a who!<' was to h<~ as lmv a.s possible. The DS . -\ 330 pantograph has independently sprung rnlfrdor ,Jr'i71s with fom spring mounts and progr<)ssive spring coefficients [9.39]. This n~d1w<~s t Ii<~ 1111sprnng rnass in direct contact with the conta.ct wire to 2,9 kg per collc~ct.or st rip. Th<' mass or Uw pantograph upp('r arm is 9 kg.
9.~_g:H\\ct of tlw clesig11_para.n1eters
501
200-.----.---,---r-----.----,---,---.---,----i
l
Figure 9.54: Contact force curve of a pantograph HSA :~GOS, overhead con-
1~0
Q)
100 - -t-~rn--•-H--11'
t? .E ~ 50
-t----t------··-----l---------t----+----+----1--+----J
Frnax
c0
= 176 N; Fmin = 78 N;
Fm (mean value of F1, 0 t.)
0
0
tact line Re 2GO, train speed 310 km/h. F\1.at. 9G N;
+----+----lf-----f---+---lf------1---+---lf------i
0
300 Distance travelled
600
m
900
128 deviation)
N;
=
.s (standard 18,2 N
The new s'ingle-a:m1, pantograph designs were to achieve virtually the same contact characteristics when running in the usual position, i.e. with the knuckle pointing opposite to the direct.ion of travel, as in the opposite direction with the knuckle pointing into direction of travel. This objective was achieved by installing suitably a.rranged air baffles which also have the effect of controlling the mean contact force, so that it increases only slightly with speed up to an approximate value 120 N at 300 km/h (Figure 9.51). The dynamic characteristics, evaluated by observing the apparent mass (Figure 9.11) were also improved considerably. The apparent mass ranges from 4 to 30 Ns 2 /m for frequencies of 1 to 6 Hz and from 6 to 11 Ns 2 /m for frequencies of 7 to 12 Hz. By contrast, the respective values of the SBS 65 pantograph range from 0,4 to 70 Ns 2 /m. The pantograph head ·with independently sprung collector strips is shown in Figure 9.53. With the aid of the methods described in clause 9.4 for systematically measuring and evaluating the dynamic forces acting between the contact wire a.nd the collector strips, it has been possible to observe the effects of pantograph parameters. For example, the spring coefficient characteristics, in a large number of tests, to derive stipulations for further optirni,,;ation work. Figure 9.54 shows a contact force recording taken at a train speed of 310 km/h. The mean contact force is 128 N a.ncl the standard dr.viation 18,2 N. i.e. 14 %. vVith these values, the targets set for the contact line/pantograph systPm have been achieved. Figure 9.52 shows the standard de,·iations of a pantograph SBS 65 operated under a standard overhead contact line design He 200 and the values obtained with pantographs SBS 65, as well as the more sophisticated designs DSA :350, DSA 350 Sand SSS 87, operated under an overhead contact line design R<~ 250. Bv cleclica.tecl further development ,vork, the standard deviations observed at a running speed of 250 km/h were reduced from approximately 26 N, achieved with the SBS 6[) to between 18 and 19 N, then to between 16 and 17 N and finally to a value _just b(\low l;'j N. This improvement was achieved by reducing the masses, introducing indep<~ndent springs under the collector strips, systematically tuning the individual st.rnct.mal compotwnts and devising as nearly neutral as possible aerndyna.111ic hJ1aviour.
502::___ _ _ _ _ _ _ _ _ _ _ _ _ __
!
i
a) trailing
2:0 b) leadiog
250
11:0
9 Interaction of pantographs and overhead contact lines
150
--1-:-llr-;tlt-l
--1~--,H---l-----l~l--r,l\·~f~..l+--+--lr-*----.!-f-_...,-rl
Q)
Q)
t'. 100--H~-t-----'-
E:' 100
._Q
Q
t5 50 --1--------+------+------+-t----------•t--------t--~-----+------+----------l co
t5 50+----------+------+------+----------l-+----+-------+-------+------1 co O --t-----------+-------+-------+--+--------+-t-----------+-------+-_, l) 0 300 600 900 m
1s l)
0 --t----------+--------+------+------+----------,t----------+----+----------+-------1
0
300
600
Distance travelled
-900
m
1s
Distance travelled
Figure 9.55: Contact force diagrams of a train with two DSA 350 S pantographs, overhead contact line Re 250, train speed 275 km/h. a) .l\5 tat 80 N b) Fst,at 80 N 215 N 162 N Fmax Fmax 17 N 70 N Fmin Fmin 124 N 122 N Fm (mean value of Ft,ot) Fm (mean value of Ftot) s (standard deviation) 23,3 N s (standard deviation) 15,0 N
9.5.4.3
Trains running with multiple pantographs
High-speed trains drawn by a locomotive use only one single pantograph. The record runs on pt of May 1988 [9.1] were carried out by a train with two traction units but with only one pantograph in contact with the contact wire. However, the traction units at both ends of the DB's high-speed ICE train are supplied directly via their own pantographs. There is no internal 15 kV connection between the two traction units and in normal operation, two pantographs will be touching the Re 250 overhead contact line at a distance of 200 to 400 m apart. The development with time, of the contact wire uplift measured at a support during runnings with multiple pantographs (Figure 9.39) shows that the second pantograph always runs along an oscillating section of contact line and is subject to less favourable conditions. This is confirmed by the contact force diagram, as can be seen in Figure 9.55. While the mean values are virtually equal, the maxima differ considerably, these being 162 N and 215 N respectively. The same applies to the minimum values, which are 70 N and 15 N. This is also visible in the standard deviations. The contact behaviour of the leading pantograph does not differ from that of a train with a single pantograph. Figure 9.56 shows the standard deviations of the contact forces measured on the leading and the trailing pantograph. The values observed on the trailing pantograph rise more sharply with speed than those of the leading pantograph, which are nearly the same as the values of single-pantograph operation. The standard deviation of the forces on the trailing pantograph reaches 24 N at a speed of 250 km/h. At 280 km/h, it rises to a value of up to 28 N. Furthermore, it is not possible to limit the mean contact force to 120 N, which has to be increased to 140 N at 280 km/h to keep arcing to an acceptable mininmrn. Such force increases are associated with corresponding force 1waks and increased wear In terms of arc suppression aud wear, it is not possible, under these conditions, t.o a.thieve the cmrent transmission quality normally demanded in siuglc---pant.ograph op<\1at.ion. For this reason. all att<~1npts should be made to transmit
9.5 Effect, of the design parameters
503
35 pantograph type · DSA 350S
pantograph type . SSS 87
N
30
125 C 0
~
>
{g 20 12
clJ 15
10
-272m
~ 10 coaches ~ _ _ _ _ _ Jg_QQQ~ - - -J!~------+------1 traction unit 2
traction unit 1
5 200
250
300 200 Train speed - - -
250
km/h
300
Figure 9.56: Standard deviations of the contact forces measured on a train with two pantographs, pantograph types SSS 87 and DSA 350 S, both leading and trailing
spacing 34 m 156 m238 m
mm
t
,;:: 100 Q_
::J
50 - + - - - - - - - - + - - - - - - - - + - - ~ 200 250 km/h 300 Train speed - - -
Figure 9.57: Effect of pantograph spacing on the contact wire uplift measured at a support, overhead contact line design Re 250.
energy to multiple traction units only via a single pantograph. The uplift of overhead contact lines at the supports due to passing trains is a parameter which affects the operational security of the system. The operating limits of standard DB overhead contact lines are in the range of 100 to 120 mm. Normally, his value should never be exceeded, since greater uplift values lead to unfavourable dynamic stresses on the overhead conta.ct line system. When trains with two pantographs run on the lines, the value at the trailing pantograph reaches this limit at a speed far below that which would be possible wit.Ii a single pantograph. Even if the two pantographs are at the maximum possible distance apart. Figure 9.57 shows hmv the pantograph spacing affects contact wire uplift, at a support. Whether and to what extent ruult.iple-pantograph open-1 1.ion is possibk also d<~pends on the overhead contact line desiµ,11. Trial nrns along an Re 330 ovei head co11t.ac-t line have shown that it is possible to use t.wo pantographs at speeds of up to 200 km/h, <\ven if they are spac< d only:{-! m apart.. \iVith a. spacing of 11101c tlia11 2,llJ 111, it. is even possihl<\ Lo ad1icv('. spc<·ds or ;~!""JO k11t/l1. 1
---~ 9 Interaction of pantographs and overhead contact lines
2
Figure 9.58: Test apparatus for measuring contact wire wear. 1 contact wire; 2 mounting disc; 3 collector pressure adjustment device
3 _
9.5.4.4
Collector strip and contact wire materials
The service life of contact wires and collector strips essentially depends on: the contact force exerted by the pantograph on the contact wire, which was discussed in the preceding sections 9.5.3 from the overhead contact line perspective and 9.5.4.2 from the pantograph perspective, the materials of which the collector strips and contact wires are made, the number and the dimensions of the collector strips, the current flowing through the contact point, the traction vehicle speed, and environmental factors such as lines in tunnels or in the open. The last three factors cannot be controlled directly or affected when designing energy transmission systems. They must be adequately considered when selecting the materials and calculating the dimensions of the components. Pure copper (electrolytic copper E-Cu) and copper alloys have come to be the primary material for contact wires. The standard EN 50149 specifies the following materials: E-Cu, CuAg, CuSn, CuCd and CuMg. Multi-component alloys such as CuCrZr and CuCrZrMg [9.40] have already been discussed as possible contact wire materials. Copper-clad steel wires have already been used by German railways [9.41] and have been considered for use in Japan [9.42]. With respect to the contact behaviour, the latter material does not differ from pure copper. Generally, it is known that copper is also used as a material for sl'iding contacts in electrical motors and generators. Depending on the environmental conditions and the contact partner material, copper will form a 5 to 20 µm thick layer of CuO and CuO 2 , which may also have graphite inclusions stemming from the collector strip material. This layer is conductive electrically and hard. It provides ideal conditions for sliding electric contacts. Various attempts have been made to use aluminium as a contact wire material. Since aluminium forms a hard oxide !aver "vhich is not conductive and must be ground off every time a collector passc'.s. enerisy transmission involves abrasion and continual arcing. For this reason, alurnini11m is not suitable for use as a contact wire material.
1,0
~
0,9 · 0,8 ·
'\'\
(])
1§
~
0,7 ·
m 0,6 ·
~ D
(])
.t-!
cij
E
contact force in N
c:=J75
lZ2Zl
150 i;sssJ 300
0,5
~
0,1 ·
zo O'3 · 0,2 0,1 0
75
150 Traction current in A - -
250
Figure 9.59: Wear rates of a CuMg 0,5 contact wire at a speed of 150 km/h. measured on a test stand according to Becker et al. [9.45].
Of the materials mentioned above, besides standard E-Cu, the alloys CuAg and CuMg are particularly suitable for contact ·wires, especially in high-speed and high-power applications. Cu Cd is no longer permitted because of the environmental contamination involved. CuSn has no decisive advantages over CulVIg. The wear characteristics of these materials were the object of a large number of studies [9.4:3, 9.44]. In recent years, the studies have been followed up systematically on a test-stand for contact wires designed and built by former AEG in Germany [9.45]. The ,vires to be tested are mounted on a disc with a diameter of 2,0 m (Figure 9.58). \,Vith a maximum speed of approximately 1500 rpm, running speeds of up to 500 km/h can be simulated. The contact force of the collector can be varied from 0 to :300 N and the AC current through the contact from 0 to 1000 A. The wear is measured by two laser sensors and the measuring circuits used enable a direct wear measurement with a resolution in the pm-region. The results of wear measurements on contact wires made of CuAg0,l and Cu:\Ig0,5 are described in reference [9.46]. As the current is increased under otherwise unchanged parameters, the wear rate decreases initially. This can be attributed to the current's lubrication effect and is clue to the formation of a lubricating graphite layer. This leads to a minimum wear rate at currents of 100 to 150 .-\ at a speed of roughly :200 km/h (Figure 9.59). As the current is increased even further, an electric wea:r component begins to take effect and the wear rate increases. The mechanical wear ccnnponent dominates, however, and this component definitely increases with increasing contact force (Figure 9.59). This confirms the importance of achieving as uniform a contact force as possible in view of optimum performa.nce of a.n overhead contact line. At constant contact forcPs and currents, the wear rn.te initially increases with speed (Figme 9.60) to a rnaximu111 value at around 150 km/h. th(~n deneases again. This _justifies the assumption that it is still possihl<~ to achiC'\T long contact ,,·ire service \if<' in high-speed applic-ati0t1." in spite of the tcnd<'11e, towards higher currents and contact forces. As a guideline. the no·,.,n1,o,l1.,c;er/ wr·o:r role <·,rn lw taken as 1 mm 2 per 10 5 pa11togrnph passages. Fig me !) GI shows a co1upa1ison of t It<' wem ul two di!f('l'<'ll1 matC'rials: CuA.gO, 1 and ('111\lg(),-> It. c;-rn he n>11d11d<'d thilt tit<' hmdcr <·0111,1ct \\it<' llladC' of Cur,Ig0.5 wears
9 Interaction of pantographs and overhead contact lines
506
1,8
-r----------------~
1,6
w
§
1,4 -
EZZa CuAg 0, 1 lsss:JCuMg0,5
; 1.2
-g 1,0 ; - - - - - - - - - - - - - - - - - ¥ 7 ' - , ' , t - - - j N
crl08E ,
~0.6 0,4 0,2 o~~~~~--~~~~-~~~~___,
50
150
100
Speed in km/h
250
300
75
150
250
Contact force in N
Figure 9.60: Wear rate of a CuMg0,5 Figure 9.61: Comparison of wear rates of concontact wire in relation to the running tact wires made of CuAg0,l and CuMg0,5, runspeed, contact force 250 N, current 300 A ning speed 150 km/h, current 300 A [9.46]. [9.46].
only half as quickly as contact wires made of CuAg0, 1, almost irrespective of the current and contact force. Therefore, CuMg0,.5 is an obviously superior choice for contact wires with a greatly increased service life. Steel, copper alloys, graphite and metallic carbon have been used as materials for collector strips [9.43]. The interactions of these materials with the contact wire differ in principal considerably. Carbon and graphite lead to a smooth, shiny surface without any visible roughness on the contact wire. By comparison, copper and steel, form a rough surface similar to that of a fine file. This roughness acts as an abrasive and leads to rapid wear, both of the contact wire and the collector strips. Figure 9.62, taken from reference [9.47], shows the wear rates of contact wires in combination with various collector strip materials. It can be seen that the metal collector strips lead to wear rates almost ten times those caused by carbon collector strips. Whereas the DB uses only carbon collector strips as a matter of principle and is able to achieve contact wire service life of 30 years and more. The Japanese railways and the SNCF use metal (i.e. steel) collector strips even in AC traction systems or used them in the past. The associated wear means that service life of only a few years is possible. Although this fact has been well known for long, these railway companies continued to use metal collector strips because they feared that the impact-sensitive, brittle carbon collector strips might shatter under mechanical impacts. The experien~e gained by German railways has shown that this rarely occurs if the overhead contact lines are optimized with respect to contact force characteristics. Metal collector strips are considerably heavier than those of carbon, leading to unfavourable dynamic characteristics. Consequently, it affects the contact forces in a negative way. Because of the heavy currents associated with DC traction applications, such collector strips are often used in DC railways [9.18]. In these cases, the copperchromium-zirconium alloy CuCrZr has proved to be very suitable because of its good thern1,al stability.
9.6 Couclusions
3,0
I I
2
I
mm /year
I I I
2,5
/d I I I I -r--------~-
2,0 -
--~--"--
I
I
Q)
C,
I
1i'i
/
I
m 1,5 -
/
I'
Q)
5
I
/
I
I I
I
/
I
/
I
1,0
I
I' I
0,5
/ --- /
b
I
I
I I I
I
I I
V I
I
a
~
/
.,,_;
/
0
0
-75
100
150 Number of trains per day
200
Figure 9.62: Wear rates of copper contact wires (according to [9.47]). a) pantograph with two carbon collector strips; b) two pantographs with one carbon collector strip each; c) pantograph with two aluminium collector strips; d) pantograph with two steel collector strips
Differences in the surface conditions and contact forces also affect the wear rates of collector strips. German railway DB achieves service lives of up to 100 000 km for carbon collector strips, while the metal collector strips used in DC traction applications have to be replaced every 30 000 km. The different contact wire 8'mface structures caused by carbon collector strips and metal collector strips mean that mixed operation of carbon collector strips and metal collector strips on the same contact wires is not advisable. It would lead to greatly increased wear rates, both of the contact wires and of the carbon collector strips. For this reason, the technical specifications for the interoperability of European high-speed railway networks [9.48] specify carbon as collector strip material.
9.6 9.6.1
Conclusions Liinits on the transmission of energy via overhead contact lines and pantographs
In the past 20 years, electric traction raihvays have seen great progress in tenns of running sp'\eds both i11 co111111crcial everyday operation and iu high-speed trials to test the pe·rfornw:nce lim,its of I.he wheel-on-rn:il system.. In 1988, the DB's experimental train ICE/V achicv<\d a speed ur 407 km/h [9.1]. Th<~ pantograph and the
9 Iuteractionofpantographs and overhead contact lines
508
D
Q)
~450+-----+-----+--,,,,~--t------+-----,----t------t-----t Cf)
400+---------+----+-------+-------t------+------+-~ 140 145 155 160 135 150 165 170
135
140
145
150
155
160
165
170
Line kilometres - - - - - -
Figure 9.63: Line profile and speeds attained, TGV-A speed record run
operation. In comparison to the trials carried out by the SNCF in 1981 [9.4], the top speed was not limited by the energy transmission characteristics but by the traction power of the train and the available track length. In May 1991, an SNCF train of an enhanced TGV-Atlantique type achieved a speed of 515 km/h on the Paris - Tours line near Tours [9.49] and set a world speed record for railway vehicles. Here again, the importance of the overhead contact line design, especially of the contact wire stress, became apparent. During preparatory runs along contact wires tensioned by a force of 28 kN, the trials had to be aborted at a speed of approximately 480 km/h due to current interruptions caused by the contact wire uplift values of more than 300 mm. The Doppler factor was only 0,040 and the amplification coefficient had already reached 8,2. Under these conditions, the possibility of current transmission had reached its limits. The final speed of 515 km/h was made possible by increasing the tensile force on the contact wire to 33 kN. Figure 9.63 shows the line profile and the speeds attained. This line, which provides favourable conditions for high speed trials, has no tunnels. It has curve radii larger than 15 000 m and a relatively steep downhill gradient at the end of which, the maximum speed was attained. Table 9.-1 sho,,·s some of the parameters relating to overhead contact line:-, used for these trials. The experience gained here leads to the conclusion that the limits to achievable running speeds are governed essentially by the wave propagation speed along the contact wire, which, in turn is a function of the tm1sile stress in the wire. This can onl:-· be increased if the maximum permissibl<:: tensile stress is increased, too, therefore requiring contact wires \Yith a greater tensik: strength. At amplificatiou coefficients of around 8,0, dynamic contact wire lifts of :300 mm and more can occur.. This is onlv tolrrablc if corresponding cantilever designs. which permit such large vertical motions rU<' insta.11<:d. During the SNCF trials carried out in 1981 [9.36], this was not th<' cas(' Tlte trial rnus wen~ ahmt,<'d wlwu th<' r:ontar:l ·1mre v,pl~ft
9.G Conclusions . --- ---
approached 200 mm and the Doppler factor reached a value of 0,073. The quality of energy transmi::;sion, d<~sirahlc from a technical perspective, cannot however, be achieved with ::;uch large vertical movements and the as::;ociatcd contact line dynamics.
9.6.2
Overhead contact line require1nents
The overhead coutacl. line equipment must be capable of reliably transmitting the electric cmT<'nt to the traction vehicles. The electrical design methods arc discussed in chapter 11. Tliese are used to determine the conductor cross-sections, especially for DC traction systems. The mechanical design dimensions rnu::;t he e::;pecially tuned to suit the nmuing speeds. The geometric and static criteria relating to the interact'i.on of the contact, lznc ·wdh po:nt,o,r;raphs arc of particular importance for overhead contact lines intended for running speeds of up to IGO km/h. At higher ::;peeds, the additional dyno:rn:ic criteria become increasingly important and these are partitularly dependent on the tensile stress in the contact wire. Table 9.5 shows the static parameters. Overhead contact lines for speeds equal to and above 250 km/h should be installed with a uniform contact wire height. Relevant data are also specified iu EN 50 119 (9.50]. It is possible to design an overhead contact line for a given speed range on the basis of the dynamic criteria. The wave propagation speed should be chosen in such a way that the Doppler factor never drops below 0,2. This means that the wave propagation speed should be between 1,4 and 1,5 times the planned train speed. EN 50119 limits the operational speed to 70 % of the wave propagation velocity. The refiection coefficient should be designed to keep the amplification coefficient below 2,0. Values around 0,4 meet this requirement. When designing cantilevers the space for maximum uplift of the steady arm shall be a minimum of twice the calculated or simulated uplift value. If restrictions or design limita.tions to uplift are provided then a space not krwer than 1,5 times the uplift will be sufficient.
9.6.3
Pantograph requireinents
Experience c1s wdl as theoretical considerations have shown that it is not possible to design pantographs solelv with the intention of optimizing the interaction with a specific overhead cont.act line design. Even standardized o,erhead contact line designs do not have u11iforn1 d,vmunic characteristics, because the span lengths, mass<\s and tensile forc-es ,, ill var\" 11n tit<'
9 Interaction of pantographs and overhead contact lines
510
t
200----~---,----,-----,--r--.------,---,------, DC1,5kVFm 0,00228 v2 +90(1) N ~ 1601----l-----+-----+--+---4-~-----t--r,-----l
E
: 120 ut==t-=--=-';;-_-=i+-=....-5-"''---+---1-=-"'+------+---+------J
e
E
c~0
80
t==:::+:::::=r-=--i--,---J--,-1-1-1
(.)
C
fil 2
40 1------+-------+---------1----+-----l----+-----,f--------+--------l
Figure 9.64: Target for mean contact force Fm for AC and (1) v in km/h 0 '----'---~-~--~--'---~-~~~~-~ 0 40 80 120 160 200 240 280 km/h 360 DC systems depending on running speed Running speed -
uplift to a minimum and avoid unnecessary dynamic excitation of the contact line installation. To achieve a satisfactorily quality of current collection the static contact force exerted by the pantograph as well as the mean aerodynamic contact force should obey certain criteria set e.g. by [9.48]. The nominal static contact force should be inside the following ranges: - 60 N to 90 N for AC supply systems; 100 N to 120 N for DC 3 kV supply systems; 70 N to llO N for DC 1,5 kV supply systems. In DC systems to improve the contact of carbon collector strips with the contact wire, s force more important, in general 140 N, can be needed to avoid a hazardous heating of the contact wire when the train is at standstill with its auxiliaries working. The target for the mean contact force Fm formed by the static and aerodynamic components of the contact force with dynamic correction specified by [9.48] is shown in Figure 9.64 for AC systems as a function of running speed. In this context Fm represents a target value which should be achieved to ensure on one hand a current collection without undue arcing and which should not be exceeded on the other hand to limit wear and hazards to current collection strips. Concerning DC systems, the mean contact force Fm should be applied for DC 1,5 kV and DC 3,0 kV systems is shown in Figure 9.64 as a function of running speed. For DC 1,5 kV lines the static con 1 act force should be 140 N where necessary in respect of the current at standstill to avoid dangerous heating of the contact wire. In case of trains with multiple pantographs sirnultaneously in operation the mean contact force Fm for any pantograph should be not higher than the value given by Figure 9.64 since for each individual pantograph the current collect.ion criteria shall be met. The mean contact force is the rnean value of the forces due to static and aerocl~'namic actions. It is equal to the sum of static contact force and the aerodynam.ic force (see clause 2.4.3.3) caus
I
.!
9.6. Conclusions ________ .___ .___
511
Table 9.5: DB Specifications for r.ontact forces at the collector strip reaction and the associated deviations, in relation to the intended application of overhead contact lines l 2 Number of pantographs Speed (km/h) Pantograph
300
Contact force (N) Maximum contact force (N) Minimum contact force (N) Standard deviation (N) Variation coefficient (%)
120 200 40 22 18
280 leading
trailing
120 185 55 18 15
140 240 40 28 20
Table 9.6: Contact force at the point of contact (N) as specified in EN 50 119 (June 2001) System Speed km/h AC :S 200 AC > 200 DC :S 200 DC > 200
Contact force maximum minimum
300 400 300 400
positive positive positive positive
considered speed. The mean uplift force is a characteristic of the pantograph for given rolling stock and a given development of the pantograph. The mean contact force is measured at the collector head, the latter not touching the contact line, according to EN 50 206-1 [9. 51]. To compley with these stipulations the static contact force of the pantograph should be adjustable between 40 N and 120 N for AC systems and between 50 N and 150 N for DC systems. The mass of the collector strips should be as low as possible to obtain optimum dynamic characteristics. The apparent mass should be within a relatively narrow range of values between 4 and 30 Ns 2 /m, depending on the frequency and should not have any sharp distinct peaks. According to [9.48] pantographs shall be equipped with an automatic dropping device which drops the pantograph in case of a failure (see EN 50 206-1 [9.51]).
9.6.4
Requirements concerning the interaction of overhead contact lines and pantographs
The interaction of a pantograph vvith an overhead contact line can be assessed by observing the contact forces and the contact wire uplift. The uplift values should be as low as possible. Although neither [9.50] nor [9.48] specify limits for the uplift it should never exceed: 100 mm for sing!(! pantogra.phs and leading pantographs of dua.l-pantograph trains, and 120 mm for trailing pantogr,tphs of dual-pantograph trains. According to [9.48] the int<'racticrn of overhead contact lines and pantographs may be assessed by the mean coutact force in c-onuection with its standard deviation or with the percentage of an:in1;, the standard deviation being limited to 0,3 · F~n and the percentage of arcing to 0, I ! % for _-\C systems and 0,20 % for DC systerns related to the 111H11ing period.
!) Int.eractiort_ of pantographs and overhead contact lines
512
\\.ith regard to the contact forces, the German railway DB has specified that overhead contact lines must have the standard deviation/speed characteristics shown in Figure 9.52. The values shown in Table 9.5 are derived from this graph. These specifications resulted in a superior current collection quality. Table 9.6 shows the contact force specifications given in E:--J 50119, Table 1. When comparing the criteria given in Tables 9.5 and 9.G the different definitions for contact forces have to be kept in mind. The DB specification refor to the measured data at the collector strip reaction while EN 50119 specifies forces between contact wire and collector strips. The compliance with these specifications may be verified by simulation calculations when designing an energy transmission system and then validated empirically by trial runs.
9. 7
References
9.1 Harprecht, W.; KieBling, F.; Seifert, R..: "406,9 km/h" Energieiibertragung bei der Weltrekordfahrt des ICE ( "406,9 km/h" power transmission during the world record run of IEC). In: Elektrische Bahnen 86(1988)9, pp. 268 to 289. 9.2 Seife~:t, R.: Der neue OberleitungsmeBwagen und seine messtechnischen Moglichkeiten zur Uberpriifung des Energieiibertragungssystems Oberleitung-Stromabnehmer (The new overhead contact line measuring car and its measuring equipment for testing the overhead contact line pantograph power transmission system). In: Elektrische Bahnen 81(1983)11, pp. 341 to 343 and 12, pp. 370 to 374. 9.3 Resch, U.: Simulation des dynamischen Verhaltens von Oberleitungen und Stromabnehmer bei hohen Geschwindigkeiten (Simulation of the dynamic behaviour of contact lines and pantographs at high speeds). In: Elektrische Bahnen 89(1991)11. pp. 445 to 446. 9.4 Dupuy, J.: 380 km/h. In: Rails of the world (1981)8, pp. 316 to 323. 9.5 Buksch, R.: Beitrag zum Verst~indnis des Schwingungsverhaltens eines Fahrdrahtkettenwerks (Contribution to understanding the vibration behaviour of an overhead contact line equipment). In: Wissensc.haftliche Berichte AEG-Telefunken 52(1979)5, pp. 250 to 262. 9.6 n.n.: Die Regelfahrleitungen der Deutschen Bundesbahn (Standard overhead contact lines of German Railway). In: Elektrische Bab 11en 77(1979)6, pp. l 7C> to 180 and 7, pp. 207 to 208. 9.7 KieBli11g, F.; Sernrall, M.; Tessw1, H; Zweig, R-W.: Die 11e1w Hochlcist1111gsoherleitu11g Bauart Re 330 cler Deutschen Bairn (The new high perfonnarn:e overhead cont,a.c:t line type Re220 of German Railway). In: Elektrische Bahnen 92(1994:)8, pp. 234 to 240. 9.8 Rwer, K.-H.; B11ksch, H.; Lerner, F., Mahr/;, R; Sdrneider, F .. Dy11arnisdw Kritericn 7,1ir Auslegung von Fa.hrleitungcn (Dynarnical criteria for the desig11 of OV(\rhead contact lines). In: ZEV-Gla.s<\rs Anw1.b1 I0:{(Ul79)10, pp. :365 to :no.
9. 7 References .. -------~-----·------"'--
··---- - - - · ·-·-·--· ·----- _ _ _ _ _ _ _ _ __:5~1~3
9.9 Buksch, R.: Theorie der Wechselwirkung von Fahrdrahtwellen mit angekoppelten mechanischen Systemen (Theory of the interaction between contact line waves with coupled mechanical systems). In: Wissenschaftliche Bericht;e AEG-Telefunken 54(1981)3, pp. 129 to 140 and 55(1982)12, pp. 112 to 122. 9.10 Beier, S.; Lerner, F.; Licl1t;enberg, A.; Spohrer, W.: Die Oberleitung der Deutschen Bundesbahn fiir ihre Neubaustrecken (German Railway's overhead contact line for their new high-speed lines). In: Elektrische Bahnen 80(1982)4, pp. 119 to 125. 9.11 Buksch, TL Eige1rnchwingungen eines Fahrleitungs-Kettenwerks (Natural vibration modes of the overhead contact line equipment). In: Wissenschaftliche Berichte AEGTelefunken 53(1980)4/5, pp. 186 to 199. 9.12 Broclkmb, A.; Semrau, M.: Simulationsmodell des Systems Stromabnehmer-Oberleitungskettenwerk (Model for the simulation of the interaction between overhead contact line and pantograph). In: Elektrische Bahnen 91(1993)4, pp. 105 to 113. 9.13 Bartels, S.; Herbert, W.; Seifert, R.: Hochgeschwindigkeitsstromabnehmer for den ICE (High-speed pantograph for the ICE train). In: Elektrische Bahnen 89(1991)11, pp. 436 to 441. 9.14 Renger, A.: Dynamische Analyse des Systems Stromabnehmer und Oberleitungskettenwerk (Dynamical analysis of the overhead contact line equipment - pantograph system). Final report, Kombinat engine fabrication electroteclmical workshop, Henningsdorf, 1987. 9.15 Nowak, B.; LinI, M.: Zur Optimierung der dynamischen Parameter des ICE-Stromabnehrner durch Simulation der Fahrdynamik (Optimizing of dynamical parameters of the ICE pantograph by simulation of the running dynamics). VDI-Bericht Nr. 635 (1987), pp. 147 to 166. 9.16 Fischer, vV.: Eine Methode zur Beredmung des Schwingungsverhaltens von Kettenwerk und Stromabnehmer bei hohen Zuggeschwindigkeiten (A method to calculate the vibration behaviour of overhead contact line and pantograph at high running speeds). TH Darmstadt 1975, dissertation thesis. 9.17 Buck, I(. E.; von Bodisco, V.; Winkler, I<..: Berechnung cler statischen Elastizibit beliebiger Oberleitungskettenwerke (Calculation of the static elasticity of overhead contact line equipment). In: Elektrische Bahnen 89(1991)11. pp. 510 to 511. 9.18 13icrnchi, C, Tctcci, G.; \i;wcfi, A.: Studio clell'interazione dinamica pantografi cate1taria COil prograuuua di sirnulazione agli elemeuti finiti. Verifiche sperimentali. Sciena. s, A. E. W.: Acrnrnt.c prediction of overhead line behaviour Iu: Railway Gazette l ut<~rnatioual ( 1977)9. pp. ;J;J9 to 343. 9.20 Li11k, J\1.: Zur 13c1edu1u11g ,011 FahrleiL1111gsschwingunge11 111it Hilte frcquemabhi:ingiger fiuit<~r El
9 Interact.ion -~l}~lntographs and overhead contact lines
9.21 Dorenberg, 0.: Versuche der Deutschen Bundesbahn zur Entwicklung einer Fahrleitung fiir sehr hohe Geschwindigkeiten (German Railway tests to develop an overhead contact line for very high speeds). In: Elektrische Bahnen 63(1965)6, pp. 148 to 155. 9.22 Heigl, H.: Messeinrichtungen zur Registrierung von Kontaktunterbrechungen zwischen Fahrdraht und Stromabnehmer (Measuring equipment to record the contact losses between contact wire and pantograph). In: Elektrische Bahnen 63(1965)7, pp. 171 to 174. 9.23 Fischer, W.: Kettenwerk und Stromabnehmer bei hohen Zuggeschwindigkeiten (Overhead contact line and pantograph at high running speeds). In: ZEV - G lasers Annalen 101(1977)5, pp. 142 to 147. 9.24 Konig, A.; Resch, U.: Numerische Simulation des Systems Stromabnehmer Oberleitungskettenwerk (Numerical simulation of the pantograph overhead contact line system). In: e i, 111(1994)4, pp. 473 to 476. 9.25 Ostermeyer, M.; DorfJ.er, E.: Die Messung der Kontaktkrafte zwischen Fahrdraht und Schleifleisten (Measuring of contact forces between contact wire and collector strips). In: Elektrische Bahnen 80(1982)2, pp. 47 to 52. 9.26 Bethge, W.; Seifert, R.: Messtechnische Moglichkeiten der DB zur Erprobung von Fahrleitungssystemen fiir 250 km/h (German Railway's possibilities to adopt measurements for testing of overhead contact line systems for 250 km/h). In: ETR~Eisenbahntechnische Rundschau 25(1976)3, pp. 162 to 171. 9.27 EN 50 318: Railway applications Current collection systems - Validation of simulation of the dynamic interaction between pantographs and overhead contact lines. Issue 1999. 9.28 Kluzowski, B.: Einrichtung zur Messung der Kontaktkraft zwischen Fahrdraht und Stromabnehmer (Device to measure the contact force between contact wire and pantograph). In: Elektrische Bahnen 74(1976)5, pp. 112 to 114. 9.29 UIC 608: Conditions to be complied with for the pantographs of tractive units used on international services 2nd edition of 1.7.89 9.30 Bauer, K.-H.; Kief3ling, F.; Seifert, R.: EinfluB der Konstruktionsparameter auf die Befahrung einer Oberleitung fiir hohe Geschwindigkeiten - Theorie und Versuch (Effect of design parameters on the negotiation of an overhead contact line for high speeds theory and tests). In: Elektrische Bahnen 87(1989)10, pp. 269 to 279. 9.31 Ebeling, H.: Stromabnahme bei hohen Geschwindigkeiten - Probleme der Fahrleitungen und Stromabnehmer ( Current collection at high speeds problems of the contact lines and pantographs). In: Elektrische Bahnen 67(1969)2, pp. 26 to 39 and 3, pp. 60 to 66. 9.32 Bauer, K.-H.; Kief31ing, F.; Seifert, R.: Weiterentwicklung der Oberleitungen fiir hohere Fahrgeschwindigkeiten (Development of overhead contact lines for elevated running speeds). In: Eisenbahntechnische Rundschau :18(1989)1/2, pp. 59 to 66. 9.33 Bauer, K.-H.; Koch, K.: Von der Versuchsobe:rleitung zur Regeloberleitung Re 250 (The steps from an experimental contact line t,o the standard contact line Re 250). In: Die Bundesbahn 62(1986) pp. 42:3 to 12G.
Q]Rcferences _ _ _ _ _ __
515
9.34 Bauer, K.-H.: Die neue Oberleitungsbauart Re 250 der Deutschen Bundesbahn fiir hohe Geschwindigkeiten (The new overhead contact line type Re 250 of German Railway for high speeds). In: Eisenbahntechnische Rundschau 35(1986) pp. 593 to 597. 9.35 Bauer, K.-H.; Reinold, !{.: Die Fahrleitung Re 250 for Neubaustrecken (The overhead contact line type Re 250 for new high-speed lines). In: Elsners Taschenbuch der Eisenbahntechnik (1980) pp. 199 to 216. 9.36 Bauer, K.-I-I.; Kie/3ling, F.: Die Regeloberleitung in den Tunneln der Neubaustrecken der DB (The standard contact line in tunnels of German Railway's high-speed lines). In: Eisenbahntechnische Rundschau, 36(1987)11, pp. 719 to 728. 9.37 Bauer, K.-I-I.; Seifert, R..: Testing of the high-speed overhead contact line Re 250 of Deutsche Bundesbahn. In: Elektrische Bahnen 89(1991)11, pp. 424 to 425. 9.38 Zoller, I-I.: Entwicklung der Stromabnehmer der Triebfahrzeuge der Deutschen Bundesbalm (Development of pantographs for German Railway's traction vehicles). In: Elektrische Bahnen 49(1978)7, pp. 168 to 175. 9.39 Bartels, S.: Versuchsstromabnehmer fiir ICE (Experimental pantograph for ICE). In: Elektrische Bahnen 86(1988)9, pp. 290 to 296. 9.40 Ikeda, K.; e. a.: Development of the new copper alloy trolley wire. In: Sunitomo Electric Technical Review. 39(1995)1, pp. 24 to 28. 9.41 Nibler, H.: Fahrleitung aus Heimstoffen for elektrischen Hauptbahnbetrieb (Contact line made of locally produced material for electrical main line operation). In: Elektrische Bahnen 39(1941)10, 12, pp. 186 to 191, pp. 258 to 259 and 40(1942)1, pp. 12 to 16. 9.42 Nagasawa, I-I.: Verwendung von Verbundwerkstoffen for Fahrleitungen (Use of composite material for overhead contact lines). In: Elektrische Bahnen 90(1992)3, pp. 92 to 96. 9.43 Kasperowski, 0.: Kontaktwerkstoffe for Stromabnehmer elektrischer Fahrzeuge (Contact materials for pantographs of electric railway vehicles). In: Elektrische Bahnen 34(1963)8, pp. 170 to 182. 9.44 Hinkelbein, A.: Der Faludrahtverschleif3 und seine Ursachen (Contact wire wear and its reasons). In: Elektrische Bahneu 40(1969)9, pp. 210 to 213. 9.45 Becker, K.; Resch, U.; Zweig, B.-W.: Optimierung von Hochgeschwincligk:itsoberleitungen (Optimizing of high-speed overhead contact lines). In: Elektrische Ba.hnen 92( 1994)9, pp. 243 to 248. 9.46 Becker, K.; Resch, U.; Rukwied, A.; Zweig, B.-W.: Lebensdauermoclellierung von Oberleitungen (Modelling of life cycle of overhead contact lines). In: Elektrisc:he Bahnen 49(1996) pp. 329 to 33G. 9.47 Borgwardt, H.: Verschleif\verhalten des Fahrdrahtes cler Regeloberlcitung der Deutsc:hen Bundesbahn (Wearing lielrnviom of the contact wire of German Railway's standard cont.act lines) . In: Elektrische lhlmen 87(1989)10, pp. 287 to 295.
516
9 Interac:tion_ofpantographs and overhead contact lines
9.48 AEIF: Technical specification for iuteropernbility. Energy subsystem. Draft 2001. 9.49 NN: Record-smashing run completes TGV speed trials. In: Railway Gazette International (1990)7, pp. 515 to 517. 9.50 EN 50 119: Railway applications ·- Fixed installations - Electric traction overhead contact lines, Brussels: CENELEC 2001 9.51 EN 50 206-1: Railway applications - Rolling stock - Pantographs: Characteristics and tests Part 1: Pantographs for main line vehicles. 1998.
10 Currents and voltages in traction power supply networks 10.1
Introduction
On the basis of the electrical requirements defined individually in clause 2.1.3, this chapter will initially discuss the electrical characteristics of railway traction power supply contact line installations. Following this, the basic problems of maintaining voltage stability in a contact line network are analyzed and conclusions are drawn about the operating currents occurring in such networks. At the end of this chapter, the reader will find a systematic description of the most important contact line circuit arrangements.
10. 2
Electrical characteristics of contact lines
10.2.1
Basic relations
Electrical characteristics such as the impedance, current distribidion and track-to-earth leakance determine the energy transmission behaviour of a contact line. The electric dimensions of the contact line and the corresponding protection required for the electric installations and operating equipment are designed in conjunction with electric power to be transmitted via this network. Once the transmission characteristics and the power to be transmitted are known, it is also possible to evaluate the electromagnetical and electrical disturbance being emitted by an electric railway line, which can be assumed to act as a very long conductor installed near ground level. Figure 10.1 shows the fundamental relationships. Supply of , Transmission of electric energy from the electric energy: substation via the contact line to the I train (traction vehicle) at the substation : I R jwL I I
, Utilization of electric : energy to propel the : consumption of S trc I I
13
- - - 1,,c Uss 2
tiU, tiP 4
Source-voltage: Resistance of contact line installation : The electric traction I power consumption Lss and the I lo traction energy transmission current 11,c : - impedance in case of alternating current supplies,:s =U . f.' : resistance in case of direct current supplies ; trc Ire ''' 1 with the following effects 1depends on the : - potential drop AU along tile contc1ct line, :status of tl1e train. ; - power loss 6.P in tile contact line :at tile respective lime 0
Figure 10.1: Electrical functions or a cont.act line.
=-:_::::__ _ _ _ _ _ _ _ _ _ _ __ 10 Currents and .voltages in traction power supply networks 518
The following equations are formulated for single-phase AC railways. Since there is no imaginary component effective in direct-current supplies, the simpler relationships applying to DC railways can be deduced from the AC-related equations. The power for propelling the train has to be transferred to the electric traction vehicle via the collectors under the respective conditions and amounts to Strc = Utrc · I;rcThis power must be supplied by the substation, and the contact line network is the medium by which the power is transferred to the train. However, the contact line and the return current path will form an electrical resistance to power transmission. This resistance can be measured by applying a voltage between points 1 and 2 according to Figure 10.1 and short-circuiting points 3 and 4. The magnitude of the resistance Z 12 is then determined from the voltage U1 2 applied between points 1 and 2 and the resulting current 112 . This resistance, generally termed impedance, is the complex value for
(10.1)
The impedance has a real component R and a reactive component X. The reactive component of impedance X is expressed as:
X=wL w is the
(10.2)
angular frequency and is proportional to the frequency f of the traction energy
network:
(;.) = 2 7r f
(10.3)
L is the inductance of the system between points 1 and 2 and can be measured when points 3 and 4 are short-circuited. The real component of impedance R is the effective resistance of the contact wire and the return current path. The total impedance is thus Z12
= R+jwL
for
Za4
(10.4)
0
If expressed in the most commonly used form, Z = Z 12 , it is obtained
Z =R
+ j w L = R + j X = Z L'.arc tan(X/ R)
Z L'.
(10.5)
In equation (10.5), Z is the absolute value (rnocfole) of the impedance and arctan(X/ R) is the phase angle
10.2.2
Impedances
10.2.2.1
Components
The l?:ne irnpedance, as the effective impedanc<~ of the loop comprising the contact line installation and the return circuit, is commonly utlled the line impedance. In DC railway installations, the line imp<~dance is t lw s11111 nf the resistances of all parallel contact
10.2 Electrical characteristics of contact lines
lines, reinforcing feeder conductors or cables and the effect.in~ track resistance including all parallel return wires. In addition to this, as shown in Figure 12.5, the effective circuit resistance of AC railways is determined by a combination of multiple electromagnetic and ohmic coupling between all conductors of the contact line installation, the conductors of the return circuit system and earth. The impedance comprises the real resistance component Rand the reactive component X and can be graphically shown with R as real axis and X as imaginary axis. In practical work, the impedances of contact lines are usually expressed ir1 relation to the length. 10.2.2.2
Resistance per unit length
The resistance per unit length of conductors, wires, cables and rails are given by the electrical properties of the materials that these components are made of A variety of statements on the individual characteristics are to be found in the relernnt publications, and for this reason, those material properties which have been specified in standards, in professional publications on contact line materials and in research reports on new contact line materials have been listed in Tables 2.11 to 2 .13. At first, the resistance per unit length of the individual components of the contact lines are determined. These components are wires, conductors, rails and earth. Wires and conductors The resistance per unit length of wires and conductors is calculated using the speqfic resistance relationship
R'
= R/ l
{! ·
l / (A · l) - 1/ ( K · A)
(10.6)
The specific electric resistance or resistivity {! of the conductor material is a function of the temperature. Up to a temperature of 200°C, this relationship is {!
= e('19) = {!20
·
(1
+ aR · ('19
20 °C ))
(10.7)
Tables 2.11 and 2.12 show the specific properties of contact line conductor materials at a normal temperature of 20°C. These tables also show the temperature coefficients aR of the conductor material resistivity. Running rails The impedance per unit length of the steel running rails of AC railways is also a function of the rnagnetic penneabilzty /Lr of the steel, which depends beside to the material characteristics on the current flowing through the rails, as can be seen in Figure 10.2. The magnetic permeability of a metal is given by: /1,
fl, · /Lo
( 10.8)
where / 11 is the ·,dat,ivc pcrrn,rn/nlzly. this being a specific pro pert\ oft he material.
520
----- - - - - - - - - -
10 Currents and voltages in traction power supply networks
::t 15
f,2 j
+------------===----=-""'t--~/-/----J
9 +------~-----lb,.,L--------------l
6+-------------,---------1 10 100 A 1000
C'.urrent per rail
Figure 10.2: Relative permeability of running rails depending on the current for 16,7 and 50 Hz. a) 41 kg/m rail, 16,7 Hz according to [10.1] b) 50 kg/m rail, 16,7 Hz according to [10.1] c) 48 kg/m rail, 50 Hz according to [10.2] d) UIC 54 rail, 50 Hz according to [10.2] e) 41 kg/m rail, 50 Hz according to [10.1] f) 50 kg/ m rail, 50 Hz according to [10.1]
Copper, which is diamagnetic has a relative permeability of 0,9999904. Aluminium, with µr = 1,000021, is classified as being paramagnetic. Ferromagnetic materials such as steel, cast iron and wrought iron have relative permeabilities in the range of 5 to 500. The value of Jlr for air, earth and most non-ferrous metals can be assumed with an adequate degree of accuracy to be unity. The value of the other factor, the coefficient of seU-inductance or magnetic space constant µ 0 , is (10.9) As derived in refernce [10.2] and [10.3] the relative permeability is given by the equation r
·vr
··'- I
µr = 20 · £. = 20 · - 1 2 rrf
/lr
D1
1
mH/km
Y'I
·'
mD/km
f
·
Hz
L; is the internal inductance of the rail and depends on frequency due to the current distribution in the conductor. As a consequence of that µr also changes with frequency. Figure 10.2 shows the measured relative permeability of running rails for 50 Hz operation. For the 41 kg/m and the 50 kg/m ra.ils additionally the values for 16,7 Hz operation werr indicated.
Earth return path According to reference [10.6], the resi.stancc per unit length of the earth return path R~ is only a function of the frequ<'llC'\. if the rdativ<' permeability of the soil is assumed to be unity, in which case\ the follmYing physical formula applies:
f
R',~ - (rr /4)/1,o · /L, · f ---- (rr (1) ·/to· f 0/km
Po
fl,
(10.10)
10.2 Electrical characteristics of contact lines ________ ----···· - · · - - - - - -
Table 10.1: Characteristic properties of commonly-used running rail types. Rail type A u 'teq U 7'eq/\ m' H Fw 2 mm mm nun kg/m mm mm rnm S49 95,5 44,77 49,43 149 125 6297 600 R50 98,7 45,31 50,50 152 132 6450 620 S54 54,54 154 125 6948 630 100,0 47,03 UIC54 54,40 159 140 6934 630 100,0 46,98 S60 60,30 172 150 7650 680 108,0 49,35 UIC60 60,34 172 150 7686 680 108,0 49,46 R65 65,10 180 150 8288 700 111,4 51,36
H Fw A req u
req A
= Height of rail = Foot width = Cross section = Circumference-equivalent radius: req u = U /2 7r = Cross section-area-equivalent radius: Teq A = ~
m' U
Mass per unit length
= Perimeter
Table 10.2: Relationship between the impedance per unit length z;ail of new running rails at 20°C, the current in the rails and the frequency, values in mD/km. 1 z;aiI in mOkmfrail f s49 1 ) s49 2 ) UIC 54 1l UIC 60 1l R65 2 l Hz A 0 all values 28,9 25,2 35,1 32,0 16,7 Hz 100 100 98 85 73 85 200 129 95 107 80 300 190 136 120 129 95 50 Hz 100 180 160 200 240 200 300 290 2-50 1) Measured values according to [10.4] 2) Calculated values according to [10.5]
By inserting equation (10.9), this leads to the following equation for the resistance per unit length of the earth
R~
= 1r2 · 10- 4 · f
R'B
.f
n/km
Hz
(10.11)
For example, the resistance per unit length is calculated to be 16,4 mn/km for a frequency of 16,7 Hz and 49,3 mn for SO Hz. For DC currents. the resistance per unit length of the earth is zero.
10 Currents and voltages in traction power supply networks
522
a) contact line
11,c
z,,ain ( track
----
i
,,,e
frE
frE - 1tre
earth b) contact line
I lire
track - - - - - ltrc
frEearth
10.2.2.3
Figure 10.3: A single-phase AC railway, modelled as a system of two coupled conducting circuits. a) contact line-earth coupled to track-earth b) contact line-track coupled to track-earth
Inductance per unit length
As depicted in Figure 4.1, from the electrical engineering aspect, an electric traction railway line constitutes of different conductors in parallel which form a system of mutually coupled current loops. As shown in simplified form in Figure 10.3 this type of system can be interpreted as being either - a contact-line to earth circuit coupled with a track to earth circuit, or - a contact-line to track circuit coupled with a track to earth circuit. If the points 1/2 (feed) and 3/4 (vehicle) as shown in Figure 10.1 are far apart, both models will lead to the same results when the impedance is calculated. The examination of two coupled conductor-earth circuits is more suitable for modelling the general relationships determining the impedance per unit length. In the following discussions, the operating impedance of the contact line of a single-track railway line, i.e. the line impedance, is calculated as the overall impedancr: of two coupled conductor to earth circuits. For the inductance calculations, it will be assurrnxl that the conductors are straight, parallel to each other and of infinite length. Furthermore, the contact line equipment is represented by a single substitute conductor, wh<'reby the mean distance between the catenary wire and the contact wire is used to ca.lculatc the dimensions of the substitute conductor. Apart from the frequency, the inductance L cktcrniiucs the magnitude of the reactance. In practical applications, tli<' worhny znductann: is 11cmnally of importance. In order to be able to cletenninc the workit1g it1dt1cta11u', !lw following individual inductances should be known:
10.2 Electrical c:harac:teristic:s of contac:tJi_n_es___ ······--· _ __
se(f-inductance of a conductor, comprising - inner self-inductance and - external inductance, mutual inductance of parallel conductors, se(f-inductance of a conductor-earth circuit and mutual induct,ance of two conductor-earth circuits. The working inductance is then calculated as the difference between the self-inductance and the mutual inductance of two conductor-earth circuits [10. 7].
Self-inductance of a conductor / The self-inductance per unit length of one conductor in a circuit of two solid conductors of equal dimensions is (10.12) whereby L( is the inner self-inductance per unit length and L~ the external inductance per unit length of the conductor. The external inductance per unit length of a conductor of radius r is given by the equation:
L~ - (µ/21r) · ln(R/r)
(10.13)
R is the radius from the centre of the conductor to a limiting circle within which the magnetic energy on which the calculation is based is to be taken into consideration. The inner self-inductance of a solid conductor with a circular cross section is found to be µ/8 1r, irrespective of the radius. For conductors, this corresponds to the expression
L;
(µ/2 n) · ln(r/rcq)
(10.14)
which contains the natural logarithm term In and the equivalent radius 'f'cq · Assuming ln(r/req) = 0,25, it is obtained req = r · e- 0 ,25 = 0,7788 · r. By relating the inner self-inductance to an equivalent radius, it is possible to describe the inner inductance of conductors, which may have different internal magnetic characteristics. The self-inductance per unit length of a conductor is thus found to be
L;i
= (µ/21r)(ln(R/r) + ln(r/rcq)) =
(p,/2n)ln(R/req)
(10.15)
This is a generally applicable equation. The equivalent radii, expressed as multiples of the conductor radii of conductors and ,vires normally used in overhead co11tc1ct lines, are listed in Table 10.3. Due to the fact that l11(r/ 1eq) - 0,25 for a contact \\'ire, the contact \\'ire inductance per unit Ieng th is
L;iCW = (11,/21r) · (ln(R/r) + 0,25) Mutual inductance of two conductors The 'lnutual 'inductance JJ
L;k = (;1.j'2Jr) · ln(/?/u.)
}O Current~and voltages in traction power supply networks
I 524 ·~------
Table 10.3: Equivalent; radii, inner self-inductances per unit length and inner reactances at a frequency of 16,7 Hz. Conductor
'l'eq/r
L\
X{
Conta1.t wires Conductors (droppers, catenary wires, reinforcing feeder wires, earth wires) 7 strands 10 ... 50 mm 2 19 strands 70 ... 120 mm 2 37 strands 150 ... 185 mm 2 61 strands 240 ... 500 mm 2 91 strands 630 mm 2
0,7788
ml-I/km 0,0500
mD/km 5,24
0,726 0,758 0,768 0,772 0,774
0,0640 0,0554 0,0528 0,0518 0,0512
6,70 5,80 5,53 5,42 5,36
!
Working inductance The combined inductance, comprising self-inductance and mutual inductance, is the working inductance. For the working inductance per unit length of conductor-conductor circuits
= (µ/21r)
· (ln(R/r) - ln(R/a)
+ ln(r/req)) = (tL/21r) · ln(a/req)
(10.16)
Self-inductance of a conductor-earth circuit According to Carson [10.6] the self-inductance of a conductor-earth circuit can be expressed as
Here again, the inner self-inductance is calculated using (10.14). The module of the external inductance of the conductor - earth circuit is calculated as:
L~E = (tL/2rr) - ln(0,738/(r ·
Jµ, · J/
{?E ))
(µ,/2rr) · ln(S/r)
(10.18)
In this equation, QE is the specific so'il resistivity and 6 is the penetration depth of the current in the earth. If all quantities are expressed in the correct SI units and the earth is assumed to have a relative permeability of 1, the external inductance per unit length is 6 - 1,85/
Jw ·µo/
{?re,=
0,738/
JI· µo ·
(10.19)
K,E
In (10.19) the term K,E is the specific rail or earth conductivity. The penetration depth of currents into earth can also be estimated quite easily using the following numerical formulae for 16,7 Hz:
c5;:::; 160 · ~
(}
{?E
for GO Hz:
1);:::; ~)(). ~
111
n-m
!QJ Elec:t~t~:aj characteristic:s_of ccmtact l in
+ ln(r/rcq)) =
L~,E - (11,/21r) · (ln(b/r)
(10.21)
(p/21r) - ln(r5/rcq)
Mutual inductance of two conductor-earth cirsuits The rnutual inductance or coupling inductance per un~t length of two circuits is determined analogously to the self-inductance per unit length. This results in the following expression for the external mutual inductance per unit length of two conductor-earth circuits whose conductors are spaced a distance a apart:
(10.22)
Overall inductance of two conductor-earth circuits The overall inductance of two conductor - earth circuits is equal to the difference between L~ E und L~< E· If equation (10.17) is taken into consideration, this is
L~E
L;
+ L~ 8
-
L~
= (µ/21r)
· (ln(r/req)
+ ln(r5/r)
- ln(r5/a))
(10.23)
(11,/21r) · ln(a/req) 10.2.2.4
Impedance per unit length
The se~f'-irnpedance per unit length of a conductor - earth circuit is calculated by combining equations (10.2), (10.5), (10.6), (10.10) and (10.21), which results in
Z{, E
= R' + R;;; + jw (µ/21r) = R' + R~ + j f
· (ln( r5 /r)
+ ln(r/rcq)) (10.24)
p, · ln(<5/rcq)
Analogously, with (10.22) the niutual irnpedance per u:n'it length of a conductor-earth circuit will be
z;, E = R;.; +.if fl. ln(r5/a)
(10.25)
The resulting overall irnpedance per unit length of two conductor-earth circuits, i.e. the line z·rnpeda:nce per unit length, is
Z' -
/ Z L,E
Z 'I. Ii:
R' + j I
-
Z' '...IJ< I•:
/I,· ln(a/r"q)
R'
-f- j
f /1, • ( [ ll (()/I)
Ir l ((}/a)
+ 1ll (r / I eq) ) (10.26)
vVlwn calculating tlw ov(~r!wad contact line impeda11<('S j)l'I unit i('llgtl1 of single-track or rn1ilt iple-t.rad:: lines, witiC"!i !llay possihlv lw (~qttipp('d \,it.Ii ,,,iuforci11µ, cottductors
10 Currents and voltages in traction power supply networks
526
Table 10.4: Resistances per unit length of conductors at 20°C, values in mf2/km. Conductor
rnrn
Cu AC-80 Cu AC-100 Cu AC-120 Cu AC-150 CA of BzII CA of BzII CA of BzII CA of BzII CA of BzII RC of Al RC of Al CA of steel
R'
A 2
80 100 120 150 50 70 95 120 150 240 625 50
New CW 215 179 146 119 560 431 297 237 187 118 45,2 4440
cw
20 % worn
/
269 223 186 149
CW = contact wire CA = catenary wire RC = reinforcing conductor
and return wires, the coupling between all conductors has to be taken into consideration in the system. The calculation of such systems can either be carried out step-by-step with the aid of the respective differential equation systems described in [10.8, 10.9), or by applying the n-terminal circuit principle according to reference [10.10]. In such cases, the relationship of the rail resistance to the current flowing in the rails can also be taken into account. In reality, the mean distances of the contact line to the rails, reinforcing conductors and return wires as well as the distances between these elements will vary. Furthermore, the number of tracks in stations differs from that along the main line. All these factors will lead to differences between measured impedances per unit length and the values calculated on the basis of material specifications and assumed mean values of dimensions. 10.2.2.5
Measuring the impedances of contact lines
The impedance per unit length of a contact lines can be determined by measurmg currents and voltages. The principle of measurement of impedance is shown in Figure 10.4. It is to be recommended that the impedances of the line be rneasured several times under identical conditions in order to obtain statistical certainty of the results, all measurements be carried out under the same conditions, e.g. the method used to establish the short circuit and the magnitude of the current through the short-circuited loop,
10,2 Electrical characteristics of contact. lines
substation
527
L
-11-1---------------------------J
'
overhead contact line~qu1pment
I
I track
location of short-circuit
----;-<~u.
/
Figure 10.4: Principle of im-
pedance measurements at an overhead contact line equipment. possible effects of the feeder line sections be taken into consideration and, if the contact line in question is an AC traction contact line, the reactive power and the effective power be measured in addition to the current and voltage in order to obtain realistic validation and comparison values. Measurements are quite simple on DC traction contact lines. All that is needed is to short-circuit the line under test and apply a measuring voltage UT between the overhead contact line equipment and the running rails at a distance L from the shortcircuit and then measure the resulting current IT. The line impedance per unit length is then calculated as the quotient of the sum of the resistances of the contact line installation and the running rails, which are connected in series, and the length of the short-circuited section (10.27)
Reliable impedance values of single-phase AC railway lines can be obtained if the length L of the measured section is considerably larger than the transition range or transition length ltr· The transition range or length describes the region within which currents are observed to pass into and out of the earth due to electromagnetic inductive coupling processes. The transition length term is explained in chapter 12. Normally it is in the region of 5 to 8 km. It is advisable to use measuring currents as high as feasable and close to the operating currents, Once the values of the voltage U, the a.pparent current I and the effective power P have been measured and the length L of the short-circuited section is known, the impedance per unit length is calculated using the following equations: cp
z
= arccos(P/(U · I))
IZI
U/I
Z'
U/(I · l)
(10.28)
If the single-phase AC lin<' 111<',1s111T11w11ts me ('anicd 01lL 1111<1<'1 the conditiou that the sliort<'d line length L is < :2 / 1 ,. 1 ll<'t <' will lw a t.c·11dell( y tu oliL1iu r<'.sist.aun~ per 1lnit
10 Currents an
528
length values which are too high and reactance per unit length values which are too low. If the length of the section being tested is very short, the self-impedance of the contact line-system-track circuit alone is measured. Example: On a 50 Hz single-phase AC railway line, measurements were taken on a 3,58 km section and the following values obtained: / U = 23,8 V; I= 19 A and P 190 W . Therefore, it results for the measured line impedance - cos
The impedances per unit length can be determined more accurately if it is possible to measure the aforementioned quantities I, U and Pat the substation and simultaneously measure the voltage Utrc at the traction vehicle's collector and the effective power Ptrc consumed by the traction vehicle. This means that the potential drop b.U = U - Utrc and the power loss b.P = P - Ptrc along the overhead contact line equipment can be determined by measurement. Analogously to the way in which equation (10.32) is derived, and with reference to Figure 10.6
b.U = U - Utrc
~ i).(J
and, as a result
z =!).(]I I
The resistance R, which is looked for, is calculated using
R
= b.P/12
The loss or impedance angle can now be calculated using the R and Z values: cp
= arccos(R/Z)
which permits the impedance per unit length to be calculated Z' -
i).(J
I (I . l)
(10.29)
This method was used to determine the impedances per unit length of the overhead contact line installation of the Magdeburg-Marienborn line on IVIay 10th. 1993. Reference [10.11] describes the values obtained by measuring the quantities specified at the traction vehicle travelling along this line, which is approximately 36 km long. Figure 10.5 shows sections of the graphic measurement recordings for a 14-minute period. From the measurements, it can be clearly seen that the train, travelling near the end of the test line, reduced power after 15:34 to enter the final test phase, and was accderated again from 15:36:45. Table 10.2 shows the results of this measurement.
10.2_ Electrical characteristics of contactJi!ies
17,00
_-· --------------'05C.::2:.:e.9
I
kV
!
I
16,75
I\ t/
~ -11
16,50
yV
~
Y\
16,25
16,00
I
I
I\
V\/ ~l I AfV 1/1/v, JM , I ;,vJL ~ J f\J vlf\ A
I\
V
hi I~ 1( M n1 VV /
l\.r-,
\/
\I
u
1-1)
V
)
hvi \
15,75 -
\lf\r
J
~ Q)
Ol
~ 15,50
\
J\
>
vv
15,25
15,00
-
400
15"40
15 35 Time/-----
15 30
7
A
MW
350
6
I--'""\.
'-
300 5 250
n
I
~
7'
~
~
~ '-01~/J"A n ~ 1 ~
,--,J'- hr" "\
'7..
't=
rr
~ ~ ~ ~ FVV~
VY
4
f
= 1trc
"'
~
200
,__ 50 -
c
3 Q
cii
s:
~
0100
0 o_
~
2
~
ht=
~
50
0
0 15 30
15 35
15 40
Time t - - - - -
Figure 10.5: Measurements of the voltage U and power P at the substation and Uuc, and the Lracti/)u <"mrent I= Itn at the collect.or of a test train [10.11].
A[('.
10 Currents and voltages in traction power supply networks
530
I Table 10.5: Resistance per unit length of running rails type S 49 and tracks according to reference [10.12], values given in mf2/km. i.9rail
oc
-30
20
Rail
Single-track line
Double-track line
gaps 34 joints/km welded 3,4 joints/km
0 15 0 15
31,4 36,9 27,3 32,0
15,7 18,5 13,6 16,0
7,8 9,2 6,8 8,0
gaps
0 15 0 15
41,0 48,2 35,7 42,0
20,5 24,1 17,8 21,0
10,3 12,2 8,9 10,5
0 15 0 15
44,9 52,8
22,4 26,4 19,5 22,9
11,2 13,2 9,8 11,4
34 joints/km welded 3,4 joints/km gaps
40
R'
Wear %
How laid
34 joints/km welded 3,4 joints/km
39,0 45,8
Values based on: Resistance measurement on a rail with 35,07 mD/km at 20°C.
10.2.2.6
Calculated and measured impedances per unit length - comparisons
The values shown in the following tables are circuit impedance values and impedances per unit length which have beencalculated and obtained by measurement. For DC railways, it can be seen that the calculated values and the measured values agree quite well. However, as Tables 10.10, 10.11 and 10.12 show, the wide variety of factors affecting the impedances per unit length of single-phase AC railways can lead to considerable differences between the calculated values and the measured values.
Resistance per unit length, DC traction systems The following tables show the resistances per unit length of overhead contact line equipment and current return circuits. The calculations were carried out using the values of the physical properties given in Tables 2.11 and 2.12. Table 10.4 shows the resistances per unit length of contact wires, catenary wires and stranded conductors commonly used in overhead contact line construction. Table 10.5 shows the resistances per unit length of rails of type S49, which are used by the Berlin metropolitan railway (S-Bahn). Table 10.6 shows equivalent values of other types of rails. Table 10.7 contains a list of the resistances pe·r unit length of commonly-used conductor rail types. The resistances per unit length of overhead contact line equipment at 20°C ancl at other operating temp<~ratures are listed in Tables 10.8 and 10.9. Equation (10.7) ,.vas used to calculate the resistances per unit length for ternperatures other than 20°C.
LQJ_Electrical characteristics of contact line::, ____________________________________.:=_5~31
/ Table 10.6: Resistances per unit length of welded rails and tracks at 20°c when not conducting any current, values given in mn/km. Rail type
S 49 UIC 54 UIC 60 R 60 R 65
R'
Wear
%
Rail
Single-track line
Double-track line
0
35,7
17,8
15
42,0
21,0
0
32,0
16,0
8,9 10,5 8,0 9,4
15
37,6
18,8
0 15
28,9 34,0
15,0 17,0
0
28,8
14,9
15
33,0
17,0
0 15
25,2
12,7
29,9
14,9
7,5
8,5 7,5 8,5 6,4 7,5
Table 10. 7: Resistances per unit length of conductor rail types, according to [10.12], values given in mn/km. Degree of wear in % '!9rail oc
0
10
15
20
2
Soft iron conductor rail 5100 rnrn , 22,5 mn/km at 20°C, 55 joints/km, 2,5 m rail equivalent per joint. -30
17,9
19,9
21,1
22,4
20
25,6
28,4
30,1
32,0
30
27,1
30,1
31,9
Aluminium composite concluctor rail 5100 mrn 6,77 mn/km at 20°c, 14 joints/km, 2,5 m rail equivalent per joint. -30
5,84
20
6,87
30
7,07
33,8 2
,
uo data available ')
Aluminium-steel composite couductor rail 2100 rrm1-, extruclecl hollow section, IG,,[4 mO/km at 20°C, 14 joints/km, 2,5 m rail equivaleut per joint -30
14,47
20
17,02
30
17,0:3
110
data availab]('
j \
I
b
J.
10 Currents and voltages in traction power supply networks
-532
Table 10.8: Resistance per unit length R' of overhead contact line equipment at 20°C, values given in mD/km. Cat.enary wire cross-sectional area in rnm 2 Overhead contact line 120 150 70 95 50 configuration 112 102 91,8 125 Cu AC-100 and CA of Bz II 136 62,3 92,4 82,3 119 108 Cu AC-100 and CA of Cu 128 115 102 160 146 Cu AC-100, 20°/o worn CA Bz II 122 90,6 78,6 137 103 Cu AC-100, 20°/o worn CA Cu 83,2 Cu AC-120 and CA of Bz II 99,2 91,5 118 110 75,3 Cu AC-120 and CA of Cu 96,1 83,7 66,9 105 140 129 114 104 93,7 Cu AC-120, 20°/o worn CA BzII 122 94,3 73,5 110 83,8 Cu AC-120, /20°!o worn CA Cu CA
/ = catenary wire
Table 10.9: Resistance per unit length R' of overhead contact lines and conductor rails at conductor temperatures of 30°C and 40°C, values given in mD/km [7.10]. Contact line equipment R' Overhead contact lines at 'IJL = 40°C 213,6 Cu AC-100 157,5 Cu AC-100 + 50 Bz II Cu AC-120 178,0 Cu AC-120 + 70 Bz II 108,0 67,2 2 x Cu AC-120 + 70 Bz II 2 x Cu AC-120 + 150 Bz II 52,5 2 x Cu AC-120 + 2 x 150 Bz II 67,5 Conductor rails at 1h = 30°C soft iron 5100 mm 2 29,9 soft iron 7625 mm 2 19,3 aluminium-steel composite 5100 mm 2 7,9 aluminium-steel composite 2100 mm 2 14,5
Line impedances of single-phase AC railways Table 10.10 shows the calculated values of the resistance, reactance and impedance per unit length of three standard overhead contact line designs used by the DB, as well as the current distributions in various configurations. Table 10.11 shows data on the impedances per unit length of 50 Hz single-phase AC railway lines and Table 10.12 for comparison, m,easurecl impedance values of single-phase AC railway lines. The differences between the impedances per unit length of upgraded lines and those of newly-built lines of the Gennan railways are quite obvious. For the impedances of overhead contact lines of type Re 200 in conjunction with type UIC 60 running rails, the following impedances per unit k!ngth are recommended as guidance values: - 1 AC 15 kV lG,7 Hz
lilll'S,
low
Clllt'Pllt (It.re rv
0)
1(h2_~IQ~~tr:ical characteristics of contact, li.u~~s ___ _
.533
Table 10.10: Calculated line impedances per unit length in 0/km of double-track, 16,7 Hz single-phase AC railway lines according to [10.8] and current distribution among the individual conductors. Over-head line Re 200
Re 200
Re 250
Re 250
Re 330
Re 330
OHL 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2
FL IL IL y y
RC II
y
n y
n n
n
y y
n
y
y
n
n
Il
y
y
y n
n y n
Tl
y
y
y
n y n y n
y
y
Il
Tl
n
y n y
y Il Il
y
y
Impedances per unit length
Current distribution (in %) FL T CA RC
R'
X'
Z.'
cw
0,148 0,152 0,073 0,078 0,077 0,080 0,038 0,043 0,122 0,125 0,065 0,071 0,064 0,067 0,035 0,040 0,126 0,127 0,064 0,073 0,066 0,068 0,036 0,040
0,140 0,127 0,105 0,085 0,091 0,079 0,070 0,052 0,135 0,123 0,101 0,082 0,087 0,075 0,068 0,051 0,126 0,113 0,099 0,080 0,083 0,071 0,067 0,049
0,206 L45° 0,198 L40° 0,127 L55° 0,115 L47° 0,119 L50° 0,112 L45° 0,080 L61 ° 0,068 L50° 0,182 L48° 0,176 L44° 0,121 L57° 0,109 L49° 0,108 L54° 0,100 L49° 0,076 L63° 0,064 L52° 0,178 L45° 0,171 L41 ° 0,120 L56° 0,108 L48° 0,105 L52° 0,098 L46° 0,076 L62° 0,064 L51°
0,74 0,74 0,39 0,38 0,74 0,74 0,38 0,37 0,71 0,71 0,40 0,39 0,71 0,71 0,39 0,38 0,51 0,51 0,29 0,28 0,51 0,51 0,29 0,28
0,27 0,27 0,14 0,14 0,27 0,27 0,14 0,13 0,30 0,30 0,17 0,16 0,30 0,30 0,16 0,16 0,49 0,49 0,27 0,27 0,49 0,49 0,27 0,26
0,49 0,49
0,50 0,51
0,45 0,45
0,45 0,47
0,44 0,45
0,45 0,46
0,70 0,50 0,68 0,47 0,70 0,50 0,68 0,45 0,71 0,52 0,68 0,46 0,71 0,51 0,68 0,46 0,70 0,51 0,68 0,45 0,70 0,51 0,68 0,45
0,32 0,38 0,32 0,38 0,32 0,38 0,32 0,38 0,32 0,38 0,32 0,39
n = no, y = yes Re 200 contact wire Cu AC-100, new; messenger wire Bz II 50 rnrn2; rails UIC 60 Re 250 contact wire CuAg AC-120, new; messenger wire Bz II 70 mm 2 ; rails UIC 60 Re 330 contact wire CuMg AC-120, new; messenger wire Bz II 120 mm 2 ; rails UIC 60 OHL overhead contact line GW contact wire CA catenary wire FL reinforcing conductor Al 240 rrun 2 (feeder line) RC return conductor line Al 240 rnrn 2 T track \,\There two overhead contact line a.re installed, these are connected in parnlleL The figures apply to one or two catenary installations, each in conjunction with two tracks and two return lines. Where the sum of the partial c:u1reILt components differs from 1,00, this is due to the phase differences between the iILdiviclua.l compoILCILts .
10 Currents and voltages in traction power supply networks
534
single track:
Z'
0,15
+ j 0,14 = 0,21 L'.45°
n/km
double track: two contact lines: Z' 0,08 + j 0,09 = 0,12 L'.50° n/km two contact lines and return conductors: Z' 0,08 + .i 0,08 = 0,11 L'.45° n/km two contact lines and reinforcing feeder line: Z' = 0,04 + j 0,07 = 0,08 L'.61 ° n/km two contact lines, reinforcing feeder line and return conductor: Z' = 0,04 j 0,05 = 0,07 L'.50° n/km 1 AC 15 kV 16,7 Hz lines, high current (Itrc rv 500 A) single track: Z' = 0,16 + j 0,19 = 0,25 L'.50° n/km 1 AC 25 kV 50 Hz lines: one contact line of a double track line: Z' = 0,17 + j 0,40 = 0,45 L'.67° n/km, two contact lines of a double track line: Z' = 0,09 + j 0,27 = 0,28 L'.71 ° n/km. In order to determine the specifications of the protective relays of the substation circuit breakers, the effective impedances should be measured on site so that the real conditions such as number of tracks and return conductor configuration are taken into consideration.
10.2.3
Track-to-earth leakance per unit length
The reciprocal value of the resistance between the rails or the track and earth is the conductance YTE· The length related value is called leakance per unit length Y,h of this characteristic has a significant effect on the return current conduction and on the track-to-earth voltage, as will be explained in detail in clause 12.4.3. Rails and tracks are thus characterized by a longitudinal resistance and a conductance to the reference earth potential, both of these properties depending on the length of the track system. The leakance per unit length is expressed in S/km. The resistance between the rails of a track is a function of the ballast resistance, which depends on the construction of the superstructure. In order to ensure reliable functioning of the safety installations which operate with track relays, this rail to rail resistance should not be permitted to drop below permissible values. The track-to-earth conductance depends on the following factors: - the superstructure structure, the sub-structure structure, th(~ degree of pollution of the superstructure, t,he WE\ather conditions and the specific resistance of the earth.
10.2 Electrical characteristics of cont.act ..fu_1es ~ - - - - · - - - - - - - - - - - -_
-35
___.::!;:)~
Table 10.11: Calculated line impedances per unit length in n/km of double-track, 50 Hz single-phase AC railway lines according to [10.8], [10.13] and [10.14] and current distribution among the individual conductors. Over-head line
OHL
Cu AC-100
11) 1 2) 21) 2 2) 11) 1 2) 21) 2 2)
+ Cu95 Cu AC-100
+ Cu 120 Re200
Re200
Re250
Re250
Re330
Re330
1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2
FL
n
ll
n y
y n
y
y
n
ll
Il
y
y
Impedances per unit length
RC
11
y
y
Il
11
Il
y
y y
ll
11
11
n
y
y
y
ll
y
y
n
1l
Il
y
y y
1l
1l
11
ll
y
V
y
II
y
>'
_,
R'
X'
Z'
0,148 0,139 0,110 0,092 0,139 0,130 0,097 0,088 0,170 0,172 0,087 0,088 0,090 0,091 0,047 0,048 0,141 0,142 0,077 0,079 0,075 0,076 0,043 0,044
0,422 0,414 0,297 0,289 0,422 0,414 0,297 0,289 0,396 0,355 0,297 0,233 0,269 0,220 0,199 0,142 0,382 0,342 0,289 0,227 0,246 0,209 0,192 0,138 0,366 0,329 0,284 0,223 0,240 0,202 0,190 0,136
0,447 L71° 0,437 L74° 0,317 L70° 0,303 L72° 0,444 L72° 0,434 L73° 0,312 L72° 0,302 L73° 0,431 L67° 0,394 L64° 0,309 L74° 0,249 L65° 0,274L71° 0,237 L68° 0,204 L77° 0,150 L71° 0,407 L70° 0,371 L68° 0,299 L75° 0,247 L71° 0,257 L73° 0,222 L70° 0,197 L77° 0,145 L72°
0,139 0,132 0,075 0,077 0,071 0,071 0,042 0,043
0,391 L70° 0,354 L68° 0,294 L75° 0,236 L71° 0,250 L74° 0,214 L71° 0,195 L77° 0,143 L72°
Current. distribution (in %) T cw CA FL RC
0,66 0,66 0,39 0,36 0,66 0,66 0,38 0,34 0,62 0,62 0,38 0,35 0,62 0,62 0,37 0,34 0,52 0,51 0,33 0,30 0,53 0,52 0,33 0,29
0,37 0,38 0,22 0,20 0,37 0,37 0,20 0,18 0,40 0,41 0,24 0,23 0,40 0,40 0,22 0,21 0,48 0,49 0,30 0,28 0,48 0,48 0,28 0,25
0,42 0,46
0,44 0,49
0,40 0,44
0,42 0,47
0,38 0,42
0,70 0,-17 0.68
0,35
0,-W 0.70 0,-17 0.68 OAO 0.71 OAS 0,69 0.-ll 0,71 0.-18 0,69 OA l 0,,1 OAS 0.69
0,-!2
o,-n
0,-!2
0,35 0,-!3 0,35 0,-!2 0,35 0,-!2 0,35
0.71
o,.rn
0,40 0,46
0,35
Cl.GS
0 .-l 1
0,-!2
1) Rails R 50; 2) Rails n 65 Note: Designations and asst1111ptions as for Table 10.10.
Table 10.13 contaills a list of w11,du.dance per 'Unit length Yalucs mcasmcd on singletrack and double-track railway lim\S. The effect of some important. factors can be observed in this Table ,rnd some of these factors will be briefly di:-;cussecl here. For ('.Xample, rneasur<~111<'t1ts liav<~ shown that the soil resistivity of sandy day soil ,vith a water content of 0 o/t. is !(] 7 Om and drops to 40 nm if the water <·onl.t)ttt. ris<'s to 30 %. Other important inll11<'t1c·< s ar<' frost and temperature changes. For ex,u11pl<·, reference [LO l] reports of 1ail-c~;11 tli condwt,rn<·<)S per unit l<'nµ,t.11 of 0, l S/k111 ii<'i11g measured 1
536
10 Currents and voltagP-s in traction power supply networks
Table 10.12: Measured line impedances per unit length, open railway lines. All values given in 0/km. No. of Impedance per OHL configuration Source .fn Where measured tracks unit, length cw CA FL RC nnn- mmmm 2 mm 2 Hz 50 I) 16,7 DR 1 0,240 L45,0° 100 [10.15] DR, average value, 1 0,215 L49,9° 100 50 [10.16] 1 0,221 L47,5° CW 10°/o worn 100 50 ditto DR, average value 2 0,117 L53,6° 100 50 ditto DB 1 0,230 L45,0° 100 50 [10.17] DB, one track with OHL 2 0,200 L47,0° 100 50 ditto DB, upgraded line 2 0,130 L48,0° 50 ditto 100 185 2 ) DB, ditto 2 0,112 L50,0° 100 50 ditto DB, ditto 2 0,118 L60,0° 50 240 ditto 100 3 95 ) DB, S-Bahn-tunnel 1 0,150 L53,0° ditto 100 4 240 ) Magdeburg-Marienborn 2 240 0,077 L40,0° 100 50 [10.18] DB,NBL 1 0,172 L47,2° 120 70 [10.17] ditto 1 0,110 L58,8° 120 70 240 ditto DB,NBL 2 0,106 L51,6° 120 70 ditto ditto 2 0,070 L63,2° 120 70 240 ditto DB, NBL, tunnel 120 70 ditto 1 0,165 L45,6° ditto 2 0,096 L48,2° 120 70 ditto Grueze-Gossau 2 0,088 L48,0° 240 100 50 [10.19] Madrid-Sevilla 50 1 120 70 240 0,330 L69,0° [10.14] 2 120 ditto 0,210 L7l,0° 70 240 Bambach-Bahn 1 0,420 L69,0° 120 70 2 0,280 L70,9° 120 70 •)
')
Notes: Contact wire of Cu or CuAg0,l; catenary wire of Bz II; reinforcing line of Al; on double-track lines the overhead contact line equipments are connected in parallel. El = existing line; NBL = newly-built line 1) Steel catenary wire 2) ACSR 185/30 3) 2 x Cu AC-100 and two catenary wires of Cu 4) one track with reinforcing line
at temperatures under 0°C and 0,5 S/km being measured at the same location when the temperature had risen above 0°C. In [10.23] comparable differences in the ratio of 1:6 are reported for Germany..
10.2.4
Capacitances per unit length
The propagation of harmonic oscillations in a contact line installation network is affected by the capacitances rwr unzt length. Every conductor in a contact linr installation also constitutes a capacitance relative to earth and is thus able to store a certain amount of electrical energy. Tb is characteristic depends on the shape and the dimension of the conductor and 011 tlw dielectri('. medium in the range of the dcdrical field under consideration.
10.2Electrical characteristics of contact lines
-------------------------·--·· -----------'c5~3:_,_7
Table 10.13: Leakance per unit length J-';f,E of track-, (guideline values) according to data from [10.20, 10.21, 10.22], values given iu S/km. Construction and condition of the track ballast
Single-track line
Double-track line
impregnated wood or concrete sleepers, clean gravel ballast, heavy frost ditto, but no frost ditto, but contaminated gravel ballast ditto, but clean sand ballast long-distance line track on gravel ballast conc:tete slab track on an insulating layer of biturnenized stone chippings impregnated wood or concrete sleepers on sand ballast with clay content wood sleepers in lignite open-cast mines concrete sleepers on gravel ballast with stone paving conc1ete sleepers on sand ballast with stone paving concrete slab track on sand bed track in tunnel, well-insulated, dry bed track in tunnel, old insulation, wet bed tracks in roads ·wk type superstructure, new, dry \Vk type superstructure, older, dry \Vk type superstructme, older, damp vV type superstructme, new, dry Vv type superstructure, older, dry W type superstructure, older, damp K type superstructure, older, dry K type superstructure, older, clamp slab track
0,02 to 0,04
0,0-1 to 0,08
0,5 1,0 1,5 1,5 0,25
to to to to to
1,0 2,2 3,3 4,0 5,0
3,2 to 5,0 2,5 2,0 3,5 10,0 0,3 2,0 9,5
to 8,0 to 5,0 to 10,0 to 25,0 to 1,3 to 8,0 to 23,0 0,005 0,02 0,23 0,05 0,1 0,4 0,5 to 1,0 1,5 to 3,0 ~ 0,01
1,0 2,0 3,0 3,0 0,5
to to to to to
2,0 4,4 6,7 8,0 10,0
6,0 to 10,0 6,0 4,0 7,0 20,0 0,6 4,0 19,0
to 16,0 to 10,0 to 20,0 to 50,0 to 2,5 to 17,0 to 45,0 0.01 0.04 0,5 0.1 0 ') 0.8 1,0 to 2,0 3,0 to 6,0 ~ 0.02
Where no specific: information is shown in the Table, the values apply to normal clamp track beds. In the case of very dirty ballast and extreme damp, the 1~rE values should be multiplied by a factor of 1,5 to 2,2. In the case of frost, a factor of 0,1 to 0,3 should be applied.
As a result, overhead contact lines, conductor rails and even tracks will have a specific: capacitance with relation to the earth. The capacitances per unit length can be desc:ri bed a.s follovvs:
Overhead contact line equipment to earth
(
.,, 'LI·:
27f c / lu(2 h./re,)
( 10.30)
Iu this ('qtiat.ion,
= co Ii
· """'', with
!wight of
tl1f'
E,., 1
=
relative p<'nuitti\·it.y ;::::; l for air and co
cont.ad. !in<' eql!iprncut above gro11ud
<'<{11i,·;d<'11t radil!s of Lhe cout;1ct. liu(' cq11ipn1c~ut.
~
G,G
Ill
8,85 · 10-!l F /km, and
538
10 Currents and voltages in traction power supply networks
~:_____---------------------~
The equivalent radius is calculated using the equation Ter
=
.T]
7
(1-ry)
. aik
(10.31)
in which r = radius of the conductor in which the strongest current is flowing, T/ = proportion the total current flowing through this conductor, and aik = distance between the conductors. Using the assumptions r = 0,006 m for a contact wire Cu AC-100, aik 1,2 m, a track spacing of 4 m and a mean height of 6,5 m above ground, the capacitance per unit length of the two parallel catenaries of a double-track line with respect to earth is calculated at 17,1 nF /km. Measurements of the capacitance per unit length of a double-track line have shown the value to be around 31 nF /km [10.24].
Conductor rails-earth The capacitance per unit length of a conductor rail with respect to earth can be approximated using the equation stated above for calculating the capacitance per unit length for a catenary. The equivalent radius ra of a conductor rail in such a calculation is Teq
= J2 A/1r
If the permittivity Ere! is assumed to be 2,5 in order to take the gravel bed below the rail into account, the capacitance per unit length of a conductor rail of cross-sectional area 5100 mm 2 and h = 300 mm is found to be 60 nF /km [10.24]. Measurements carried out by the former East German railway company, DR, have shown capacitances per unit length to be between 70 and 100 nF /km. Track bed-earth According to reference [10.25], the capacitance is calculated as c~E
= 7r EI ln(2 ha I h 2 + a 2 )
(10.32)
in which a h
track gauge (distance between rails) height of rails above earth req equivalent rail radius Ere! ~ 2... 3 for a dry gravel bed. Here too, the calculated values are lower than corresponding measured values. In reference [10.22], the measured capacitance per unit length of the four rails of a double-track line with respect to earth is recorded as being 120 nF /km.
10.3 10.3.1
Voltage regulation in contact line networks basic requirements
When electric power is transrnittc)d from the substations to the traction vehicles moving along the contact lines, voltage dn1ps will ocTm along the rnntact lines.
~Q._~ Yoltage regulation in contact line netWCl!:_~----··--·--·- ___ a)
R'I
_________ 539
___:::___:::__::__
jX'/= jwL'/ ~
b)
j
/
lr0
,s:>,
lire R' cos cp ltrc X' sin cp
c)
j
Figure 10.6: Voltage relationships in a traction power supply contact line network. a) Equivalent circuit b) Vector diagram of voltage drops, train drawing current c) Vector diagram of voltage drops, train braking
Conversely, if a vehicle capable of feeding braking energy back into the network is braking, the voltage at the traction vehicle position will rise in order to transfer braking energy to the contact line network. Thus the potential at the collector of a traction vehicle will depend on the electrical characteristics of the contact line installation as well as on the present power consumption of all electric traction vehicles in the feed section and their respective distance from the feed point. Under normal operating conditions, the voltages should never exceed or drop below the nominal voltage tolerances given in Table 1. 1. In railway lines for high-speed traffic and heavy traffic, the recommendations are stricter [10.26], stating that the voltage of the electric traction contact line network should never drop below the nominal voltage at any point of the network in normal operation. In the draft of the UIC-leaflet 796-0 of December 1996, a mean useable voltage at the collector is defined, this being 2,8 kV for 3 kV railways, 14,2 kV for 15 kV railways and 22,5 kV for 25 k \. railways. These voltages are defined as minimum values. For high-speed traffic, stricter requirements are formulated, stating that the mean useable voltage must be nearly equal to the nominal voltage in order to fully utilize the vehicles' power and achieve high performance.
10.3.2
Basic principles
Figure 10.6 shows a simplified 1·rrm:ualcnt circuit diagram of a contact line iustallation dettH!llt and the con c'spo1tdi1tg potential difference vector diagrams. lu this illustration. tlt<' /01urilwl111.!ll voltage drop due to the traction rn1re1tt l 1n flowing
10 Currents_and_ voltages in traction power supply networks
540
through the resistance and reactance can be deduced as
6U1 = l(R' lt,c COS
+ X' It.re
sin
for the lateral voltage drop per '/1,nit length
6Uq
= l(X' ltrc
COS
and thus for the overall voltage drop fl[!
= (Uu - Utrc) - lft.rc(R' + jX')
For all practical applications, the lateral voltage drop caused by the traction current ltrc is negligible, so that it is possible to use the longitudinal voltage drop 6U1 instead of the overall voltage drop 6U. In an AC traction energy supply network, the voltage drop between the substation and a traction vehicle located l km away and which is drawing a current ltrc can be described with sufficient accuracy by the equations 6[1 = Re{ 6U} = ltrc l
lZ'I =ft.rel Z'
(10.33)
where 6U ~ 6U1 = ltrc l (R' cos
6U = Itrc l R'
(10.34)
A comparison of the diagrams in Figures 10.6 b) and 10.6 c) shows that if a train is braked electrically with energy regeneration, the voltage Utrc at the collector must be increased in order to feed the energy back into the contact line installation network. The braking energy can be used to supply other traction vehicles in the same feed section and/ or be fed back into the electric power supply network which feeds the railway traction network. The voltage of the traction vehicle collector which is returning energy to the network is determined by the respective energy recovery conditions. The above equations only differ with respect to the resistances. As has already been explained in clause 10.2, the sum of the resistances per unit length of the contact line and the return current conductors, R', is relevant in DC traction systems, whereas in single-phase AC traction systems the module of the line impedance JJer unit length Z' determines the voltage drop. The voltage drops and the currents flowing in the contact line installations are associated with corresponding erwrgy dissipation, i.e. power losses. The power losses are caused by the effective resistances of the contact line network. E\·ery effective resistance R through \vhich a current I flows will dissipate power
6P = 12 · R
(10.35)
in the form of heat energy. Corresponding to this, the power loss due to the resistance per unit length along a DC traction conta('t liue or the effective resistance per unit length of an AC traction ('Ont.act line is
6P' - 12
.
HI {
(10.:36)
10.3 Voltageiegulation in contact. line networks
10.3.3
Voltage drop calculations
10.3.3.1
Introduction
541
In the following section, the voltage drops occurring between the feeding substation and the current position of one or several trains within the same feed section will be calculated. Apart from the traction current, distance and impedance per unit length, the type of feed will determine the voltage drops to be expected. The least complicated relationships apply in the case of single-end feed to a single train drawing current from the traction power network.
10.3.3.2
Single-end feed
One train in the feed section In Figure 10.7, the voltage drop from the substation up to a position off as
The rn,a:rirmm1, voltage drop feed section. In this case
/::J,,.Umax
1:
can be read
will occur when the train reaches the far end of the
If the traction vehicle travels along the section at a constant speed, the graph can be plotted against time instead of distance. The expected voltage drop is l
6U - -1l .;· 6U..1• d:r
=
1
2 111. .<.· Z' l
(10.37)
0
Several trains in the feed section If the equivalent designations from Figure 10.7 are used, the voltage drop between the substation and the third train can be calculated as
or, if this is ge11era[i7,ed to descrilw n trains in a feed section 11
'/l
6Un
Z' L I;l 1
-
Z' L Iuci :r;
( 10.38)
i=I
If the number of trains within a feed section is ,ery large, the theorPtical boundary ms<' of' a ·u,n1,fm·rnly-ci1.st:rilmted line load a.s shown in Figure HL7 c) is ad1ie,·ed T'he line load iu a contact !in<' fopd section can be defined in rcJation t.o the le11gt.h as f'ollows
(10.JD)
10 Currents and voltages in traction power supply networks
542
a)
I 6
I
X
tI
t
J.,,
:::i
::5
0.
"O
"O
0
0
Q)
Q)
0)
i 0
El
0
>
> Distance
b)
X
1-·--~-~--/_2 ___ I
· 1
--13 X X
ft,c3
t:..ux
_______
:::i
::5
1
0.
!2
-0 Q)
!2
-0
: - - - - - - .....C:::-::. ~O_H~ -
0)
El
g
0.
I I
-
1
Q)
JOHL
0)
El
I I
0
, £ _ __ _ _ _ _ ,_ _ _ _ _ __ , _ __ _ _ _ _ _ _ _ _~
Distance -
o
t I.
X
)
•
>
X
~
! ::5
A~
:::i
0.
0.
D
D
0
0
Q)
Q)
0)
0)
El
~
o - - - - - - - _!OHL o > ~-------------------~~> Distance
X
Figure 10. 7: Voltage drops in a section with single-end feed. a) one train in the section b) two trains in the section c) uniformly distributed load (iine load)
The current flowing IoHL in the contact line section at a distance is then
.T
from the feed point
as can be seen in Figure 10.7 c). This expression enables the equation for the voltage drop between the substation and the point x to be defined for a uniform line load distribution:
Z' 6Ur" = . I-r.' Z' ci.T - l (l :r
1/,
1:
j
()
:i:
2
/2)
L ftn i
I
i
(lOAO)
10.3 Voltage regulation in contact line networks
543
For the special case of n trains drawing equal currents
,0.i..U:r.
n
ltrc
Z' (l :r
:i:
2
Ir.re,
(10.41)
/2)/l
If it is assumed that all trains travel along the section at a constant speed, the same assumption as used above can be made. With this, the mean value f::i.U
( 10.42)
(1/3) n ltrc Z' l
and the maximum value (10.43)
l::i.Umai: - (1/2) n ftrc Z' l
can be calculated. In practice, however, the voltage drop will be greater than a value calculated using (10.42) because a realistic number of trains in a single contact line feed section will be between 1 and 3 to 5 and not infinitely large as assumed when deducing (10.40). To solve this problem, reference [10.27] specifies an equation which will produce adequate results for the mean voltage drop. This equation is
l::i.U = (1/3) ltrc Z' l (n
1, 5 O:
-
(10.44)
1)
in which c."t is the quotient of the period between two acceleration processes and the total period of time that power is drawn from the contact line network. Values of o: obtained by empirical methods range from 2 for regular train traffic to approximately 4 to 6 for metropolitan mass-transit train traffic [10.28].
10.3.3.3
Double-end feed
One train in the feed section The feed conditions can be seen in Figure 10.8. Lis the distance between the two feeding substations. In double-end feeds, the length of a feed section is defined as l - L /2, and assuming that UA - U13 = U and that R' and Z' are constant between the two substations, the voltage divider rule leads to the equation
(IA/ ltrc) = Z' (L
:r)/(Z' L)
Taking substation A as a reference point, the above considerations li::ad to an expression for the voltage drop between the substation and a point x f::i.U:r. -
ltrc
Zre I ( :r - :r 2/ L)
(10.45)
and for the maximum \Vhich will occur at the point :z: = L/2:
l::i.U111 a:i:
(1/4)
ltn·
Z' L
With the assumption made above, i.e. L
= 2 l, it is obtained
10 Currents and voltages intraction power supply networks
L a) A
21
;,_I---.------------------,.,1
t1~x~1
ftrc
-
XAn X Ak
XnB
XkB
X
X
b)
B
X 1B
X A1
/A
ftrc1
ls-
-[Altrc1 !1 ft,c2
ltrck
11,cn
/F ::::i
Q.
e
"O
/j_j X
Q)
0)
2
g
"'----__,_-----~------~--~-x
c)
Wx
::::i
Q. 0
i5 Q)
~
g
"'--------------=-"-----------'--X
Figure 10.8: Voltage drops and over head contact line currents in sections with doubleend feed. a) one train in the section b) n trains in the section c) uniformly distributed load (line load)
The mean values are deduced in a similar manner as
6U
=
(1/6) Ii.re Z' L
(1/3) Itrc Z' l
( 10A6)
If the contact line installations of a double-track line are cross-coupled a.t the midpoint of the feed section, the voltage drop elm~ to a train tra,elli11g 011 one of the parallel sections is clescrihccl by the following equations [10.28]:
6[/1:
= ftrc Z' (;r -
6Umax
= (1/6)
fuc
:3 :i:'2 /(2 L)) (1/3) Ii.re Z' I
Z' L
~U - (1/8) Itrc Z' L
(I
/i)
11" Z' I
(Hl.-17)
545
Table 10.14: Voltage drops in contact line network /i:)ed sections [10.28]. Type of feed
Number of trains in the sectio11
Instantaneo11s value flUx
l'viea.11 value !lU
Maxi1n11111 value f::i.U,11ax
siugle-enclecl
n iu
:1:
l/2
l
l · n/3
l · n/2
l·(n+l,5n-l)/3
l·(n+l,5n:
l/3
l/2
l · n/6
l · n/4
l · (n + 2o: - 1) /6
l·(n+2o-1)/4
n, uniform load
( f, ltn,,;:I:;) / ft
1
re
1) /2
1==1
n iudividual loads n, uniform load 1
dou ble-encled
n individual loads
double-ended with ClOSScoupling
:r(l -
:i:; (2t))
see eqn. (10.48) :c - 3:1:
2
/ (
4t)
l/4
n, uniform load 1
-
l/3
l · n/12
l · n/8 [. (n + 3u - 1)/8
l·(n+3o:-1)/12 All formulae and expressions must be multiplied by l 1rc,R' for DC railway installations and by hrcZ' for AC railway installations
Note:
Several trains in the feed section Under the assumptions and conditions described above, the instantaneous value of the voltage drop between substation A and the train number k is given by k
XA,k)
L
Tl
ftrc,i :i:A,i
+ XA,k
i=l
L
ftrc,i
(L
XA,i))
(10.48)
i=k+l
If the voltages UA and U8 of the two substations are not equal, the right-hand side of equation (10.48) must be supplemented by the sum :rA,k (VA - U8 )/ L. In this case, a compensating current Ia will flow through the contact line section from one substation to the other if there is no load along the section. The value of this no-load compensation c'Urrent will be (10.49) Assuming all traction currents to be equal and applying (10.40): n
6U = Z' L /12
L
n
11.,c,i - Z' l /6
i=I
L
ftrc,1
i=I
.0:.c·,,wr = (1/8) n It,c Z' L
(1/4) n 11.1 c Z' l
If the factor n and the 11umbcr of trains n currently in the foed section are k11mn1, then th<' lll(';-111 ,·alue will be ft.,c
Z' L /12(n
+ 2n, -
1)
= It.re Z' l /6(11 + 2n -
1)
( 10.50)
Table 10 . 11 surn11w.rizcs tlw expressions needed for calculating the voltaqe rlrnps for difr<'r<'lll LytJ('.s of cont.act liuc f<><'d S<'ctions. In ord('t t.o allow easier <"Olllparis01i of tli<' n'stilLs, nil l<'1tgtl1s an' e.xpn~ss('d ndatin~ to a c·o11L1d li11<' sc~ctioll of' l<'1tgLl1 /.. wlwreh,
546 _ _ _ _ _ _ _ _ _ _ _ _ _ _ 10 _ Current~ :=....:.::___ __ __,md voltages in traction power supply networks
~ l:,.Uxe
0, 7 5 t - - - - - - - t - - - t - - t - - - - - - - t - - - - - - - - ;
1 o._
e D
o,5 1-------J-------r--==-------t--------1
Q)
~
0 >
11?
ii
& 0,251-----h'--;£--+-r--=-----''1"----~=-----'-s-+---',~-----l Af/
z,l<-oo
0,5
0
(SSA)
Relative distance - - - -
1,5
2 (SSB)
Figure 10.9: Voltage drop graphs of cases with equal total loads, different types of feed, without crosscoupling, with one cross-coupling and with three cross-couplings, relative to the voltage drop 6.Uxe occurring with single-end feed and with one train in the feed section. Meaning of the indices: e = single-end feed z = double-end feed k = number of cross-couplings between the substations
the length of the section under consideration in the case of dot1ble-ended feed is defined as half the distance L between the substations, i.e. L = 2 · l. A feed section of length 1 is thus considered to extend from the feed point up to the coupling point between substations or, for terminating sections, up to the end of the section. The theoretical limit n --+ oo and Itrc --+ 0 gives a value for the uniform line load which can be calculated using (10.39). Figure 10.9 shows a graphic comparison of the different voltage drop situations for equal total loads in the section between two substations. This graph also demonstrates that increasing the number of cross-couplings within a feed section improves the voltage conditions in a traction power contact line network.
10.3.4
Other calculation algorithms
For high-speed and heavy-traffic lines, it is advisable to calculate determined values of the voltage conditions in the contact line network because the characteristic train traffic patterns cannot be assumed to be random processes. In [10.29] an algorithm for calculation of voltage drops is developed for this purpose. The respective train traffic simulation, with the associated railway network calculations, are described in detail in reference [10.28]. Data and descriptions of voltage conditions deduced by this method for high-speed traffic are given in [10.30]. Figure 10.10 shows examples of high-speed train collector voltages calculated [10.29] on the basis of the method described in [10.30]. The upper part of the illustrations shows the arrangements of the feeds of the two systems, 1 AC 15 kV 16,7 Hz and 1 AC 25 kV 50 Hz. One import.ant difference !wt.ween the energy supply arrangements is that single-end feeds are used in the 50 Hz svstem as opposed to double-end feeds
10.3 Voltage regulation in contact line ne~works ---
547
----------
a)
110 kV 2 X15 MVA 15 kV contact line installation
b)
•
SS1
100
50
0
I
•
I
SS2
•
SS3
I
•
I
SS4
I
•
200
150
I
SS5
I
•
SS6
Structure of the traction power supply for /
I
I
•
SS7
I
I
•
I
SSB
1
I
• SS9
line kilometres substation locations
50 Hz
c)
16,5
h adway ++---++-----+--+----+--+----+---t---h--.rl--l
kV
d)
kV 27,5 -l+-------'--+---'---1---''---+------'------+-'---+-------'--+--'-----+----1--\--l---l
50
100 Distance - - -
150
km
200
Figure 10.10: Calculated pantograph voltages of high-speed trains with lG, 7 Hz and 50 Hz feeds. a) Structure of traction power supply fr>r 1 AC 15 kV 16, 7 Hz b) Structure of traction power supply for 1 AC 25 kV 50 Hz c) Voltage at pantographs for l AC 15 kV Hi,7 Hz, headways 4, 10 and 30 minutes d) Voltage at pantographs for 1 AC 25 kV 50 Hz, headway 4 min.
lO_gurrents a~cl ~oltct_g,es in traction power supply networks
548
in the lG,7 Hz system. The lower part of Figure HUO shows the collector voltages of the tractiou vehicles as thr\y travr\l aloug the line, which has a length of 200 km. Other methods have also lweu developed for assessing the voltage conditions in contact line networks of conventional, normal-load railways. These include calculating voltage drops for mixed load conditions, - calculating voltage drops using stochastic methods, and estimation calculation of the rna:r:imnrn voltage drops. These methods are also described in detail in [10.28].
10 .4
Operating currents
10.4.1
General
Electric traction power is transferred to a moving train by a current flov:ing through the contact line installation. This traction current is driven by the voltage applied to the traction vehicle's collector and its magnitude is inversely proportional to the effective impedance of the traction vehicle. The traction vehicle impedance, in turn. is inversely proportional to the rated power of the vehicle and also depends on the current setting of the power control circuit of the vehicle. In power supply systems in which the nominal voltage is the descriptiw characteristic the rated power of the traction vehicle will be the quantity on \\·hich the operating current calculations must be based. The time function of traction currents drawn by moving trains can be analyzed by simulating train runs and is determined· by the parameters of the respective run. In a contact line installation. the traction currents of all trains travelling in the same feed sections at a given time \\·ill be superimposed.
10.4.2
Traction currents of traction units
The traction current of trac:tzve v,nits, i.e. the current required to driYe a train, depends on line profile, the running speeds and other train dynamics parameters and is usually expressed as a function of time: Itrc(t). Figure 10.11 shows typical examples of traction current/time graphs. Table 10.15 shows guide values of maximum expecred operating currents. These values have been based on experience and measurements
10.4.3
Currents in a contact line section
10.4.3.1
basic considerations
A contact line feed sec/;·wn is that section of an electric train li11<' \\·hie Ji is foci by a particular substation. In s.\ str'ms with double-end feeds, the sect ion i::; considered to extend from the foed point Io the mid-point between C'.Onsecutin~ f<,ed puints. Depending on the k,11gtlt / of the section and on the train speeds, one t>r scH,ral trains may be in the sanw f<'<'d sc·ctiou nndr'r normal traffic conditions. as can lw seen in Figurns 10.7 and 10.8.
!_9,4 Operating currents
549
a)1000 A
-
r
J
1:: c
~
I
!
400
11
~
I
11r
-·-
·- ,_I
200
:5 ~ 0 0 u-200 ~ 1- -400
I,
w 2000
1000
0
3000
4000
5000
s
6000
Time - - -
b) 1200 A
:~~
L
1400
'---
~ -------
.
'"
;/ fl
~ 200
3
V
/
~
~
0
1
) \ \~
5-200
TI
~-400 -600 -800 -
V
5
0
10
15
20
Time c)
\(
1 200
,.
/
25
~
:5 (.)
/ /
t5ro
'
''
'
''
/
/
100
2
''
,.
c 0
s
300 A
C
2
/ /
/
i-=
100
200
300
Time
s
400
Figure 10.11: Traction currents It.re plotted as functions of time. a) DB ICE with two traction vehicles, travelling on the HanoverW iirz burg high-speed line without stops [10.31] b) Local-area trains 1: T\-amway T4D (Dresden) T4D + T4D + B4D, run on level stretch, chopper controls 2: Tramway. GT6N (Mannheim), unoccupied, measurement run [10.32] c) Long-distance traffic, direct-drive locomotives 1: passenger train, 400 t, 'Vmax = 110 km/h 2: Goods train 1500 t, 'Vmax = 70 km/h
The train loads and thus the load currents of contact line feed sections of generalpurpose railway lines can be described as stochastic functions, as is demonstrated in clause 11. 1.1. 2. However, in high-speed traffic, there is normally only one train in each feed section at a time. The current load is thus intermittent. Such loads are described in more detail in cla.use 11.1.1.3.
10.4.3.2
General-purpose railway lines
Clause 11.1.1.2 describes the characteristics of railways for general traffic. The tirnedependent load in a particular section can lw descrilwcl using the equations (11.7), (11.11) and (11.52). In order to be able) to detennine the electric.al parameters. data an~ 1weclecl on the load cunents to he expected. Since the instant,meous load cases as shnwn in Figure 10.8 onlv nppl\" to a part.iC'11lar 1110111e11t of time. it is necessan
--o
10 Currents and voltages in traction power supply networks
·=-:;);)~----------------------~
Table 10.15: Guideline values of expected maximum operating currents in various power supply systems. ' Power Rated Auxiliaries Probable maximum currents Vehicle/ supply power Individual Double Contact train type system traction vehicle/train line section kW A A kW A 172 1200 DC 600 V 70 600 T4D Dresden 3000 GT6N Mannheim DC 600 V 480 80 780 1700 4000 DC 1500 V 4500 4500 AEL Hong Kong 5300 800 3000 l) 2340 Munich subway DC 750 V 1050 4500 3200 2 ) Berlin heavy rail DC 750 V 2400 4500 800 AC 15 kV 2400 250 DB, BR 420 110 500 1200 DB, BR 120 ditto 460 1800 6400 800 800 ditto 3720 290 1000 DB, BR 112/143 600 550 420 3 ) DB, ICE ditto 840 1500 4800 500 DB, ICE 3 ditto 1450 2000 8000 500 725 SNCF, Thalys AC 25 kV 4440 200 400 800 500 DC 1500 V 1840 1500 500 3000 1) Triple train;
2) 4 x Br 481 +482;
3) per traction vehicle
~ I
[OHL
A ~ S S B
1 -' I
-.0 c
l=loHL (1-2 xii) (// 2)
~ Ix>------~, :J
0
X
Distance - - -
Figure 10.12: Contact line currents IoHL between two substations under the assumption of a uniformly distributed line load IoHL according to (10.39).
to use the line current loads IoI-IL in calculations. The line load can be deduced from the power per unit length P' on which the design of the electric railway system was originally based :
I;HL
= P'/(Un · cos
As shown in Figure 10.12, the current flmving at any point a distance left-hand feed point of a contact line installation is
l.1: = P' · (l - 1:) / (U cos
(10.51) .'.C
away from the (10.52)
At the feed point itself, the current flowing into the contact is
fr=O = P' · l / (U11
•
COS
(10.5:3)
The values shown in Tabl<\ 10.16 can serve as realistic guideline values for typical power loads per unit length. For 1 AC lC> kV 16., Hz railwciys. the m,ean power factor cos;;
10.4 Operating currents
Table 10.16: Guideline values for the power per unit length P' on double-track electric railway lines, values given in kW /km.
P'
Type of railway and traffic Lines with little traffic, trains at up to 120 km/h Lines with heavier traffic loads, trains at up to 160 km/h - Lines with very heavy traffic loads, trains at up to 200 km/h - Local-area railways, 10 000 passengers per hour and direction, trains at up to 80 km/h, starting acceleration 1,1 m/s 2 Local-area railways, 40 000 passengers per hour and direction, trains at up to 80 km/h, starting acceleration 1,1 m/s 2 High-speed railway, 6 minute headways, trains at up to 330 km/h, 8000 passengers per hour and direction
up up up up
to to to to
300 500 600 750
up to 3000 up to 1300
can be assumed to be 0,83 and for 1 AC 25 kV 50 Hz railways it can be assumed to be 0, 76 if exact values are not available. In the UIC leaflet No. 795-0 of December 1996, a value of 3 MVA/km is mentioned as the power per unit length to be installed for double-track high-speed traffic lines. This value is extremely high. The value 5,5 MVA/km mentioned in the same publication as being the power requirement of a line with a train headways of 2 minutes and speeds of up to 200 km/h only applies to exceptional cases. These installation power specifications take into account reserve capacity which is not detailed in any way in the document. For this reason, calculations of expected currents should preferably be based on the traction power per unit length values given in Table 10.16. Exarnple: Determine the line load and current in a contact line feed section of railway line with very heavy traffic, 15 kV nominal voltage and on which trains travel at up to 200 km/h. In Table 10.16, the power per unit length required for this type of traffic is given as being 600 kW /km. With an assumed mean power factor of 0,83, the current per unit length is ISHL = 600 kW /km/(15 kV· 0,83) = 48,2 A/km
If the distance between substations on this line with double-end feed is 50 km, a contact line feed section length of 25 km must be used in the calculations. The feed current for one track is then calculated as
Ix=O = USHLf2) · l
24,1 A/km· 25 km= 603 A
The currents calculated using equation (10.53) can be considered to be the currents drawn in the peak-load hour according to equation (11.11) because they were derived from the assumed maximurn load values. The corresponding Iii max values can then be used to calculate the currents for defined periods as described in clause 11.1. 1.2. 10.4.3.3
High-speed and heavy-traffic railway lines
As explained in detail in clause 11.1.1.3, the load currents of hiqh-speerl and heavytraffic railway lines are intennittent in characteL The effective loads nm he calculated using the algorithms descrilwd in those c-la11s('S.
!i''i :1
10 Curwnts
552
and
voltages in traction power supply networks
Although the load curn~nts in double-end feed sections of heavy-traffic lines with large loads are intermittent, they can be described in simplified form with the aid of equations (10.51) to (10.53). Due to the high tra.in frequ<~ncy on such hea\·ily-travelled lines, the load currents exhibit a low statistic variation. Expressed quantitatively, a normalized scatter, i.e. a coefficient of variation, of less than 0,1 can be expected in these cases. As this complies with the condition that the variations must be very low, the assumed quantity described as the load current per unit length can be used as an acceptable basis for estimating the required 8Ub8tation capacity. Example:
What is the current per unit length and the feed current in a contact line installation of a double-track local-area railway line with heavy traffic if the power per unit length is 3 MW /km, the supply voltage is DC 1500 V and the substation spacing isl= 4 km?
Iom,
3000 kW /(km· 1,5 kV) = 2000 A/km
,
Ix=O = (IOHL/2) · l/2 = 1000 A/km · 2 km= 2000 A
10.5
Contact line circuits
10.5.1
Basic requirements on contact line circuits
In order to ensure reliable operation of electric railway lines, the contact line installation must be subdivided into electric 8ection8 which can be switched on or off or isolated in such a way that it can still be operated in the case of faults in or planned disconnection of particular sections. When drawing up configurations, designing and constructing contact line installations, the following aspects must be taken into consideration with regard to the contact line circuit: The circuit must enable optimum efficiency of the contact line installation with the least possible voltage and power losses in regular operation. The contact line installation circuit must enable distinct, small localized sections of the contact line installation to be isolated in case of necessary maintenance or repair work or in case of short-circuits. Electric rail traffic must be continued in the unaffected sections. This circuit design principle, in conjunction with the respective protection concept, is also called the 8electivity conJiguration. The contact line installation circuit must be clearly understandable and easy to monitor in order to prevent. erroneous connections and work accidents. For this reason, the circuits used in public railway networks should be designed in accordance with standardized practices ancl aspects. The additional contact line network operating equipment necessitated by the respect.in'. circuit design, such as circuit-breakers, section disconnectors, section 1:nsula/01.s and insulated overlaps should he restricted to the necessary minimum.
10.5 Contact line circuits
The development of the contact line installation circuit configuration and design thus involves achieving a sensible ba.lance bctvv<)cn the r<\spective measures required to comply with the requirements of electrical engineering, protection, railway operations, maintenance and e<·onomics. In addition, town-planning aspects frequently have to be taken into consideration when drafting contact line circuit configurations for clcctrir local-area railway networks. The criteria listed above are taken into consideration and the calculated power requirements, the location of the power supply lines from the main energy sources, the railway line profile and the location of the fixed railway installations are then used to draw up line feed configurations, also called line feed plans by DB (German rail company). These are then used as a basis for the contact line cirwit designs.
10.5.2
Basic types of circuits
Substations supply electric power to the electric traction vehicles within a specific section of the network. This part of a contact line installation is also termed a substation s1tpply section. A contact line section which receives its power from a section feed branch or section terminal of a substation via a particular feed line is called a contact line feeding section. Especially in the case of main railway lines, the overhead contact line feed sections between two substations are subdivided into switching sections and these, in turn, are further divided into switching groups. This principle is explained in detail in 10.5.3. Figure 10.13 shows the basic cirwits of contact line installations for electric: railways. For the sake of clarity, no switchgear has been drawn in. The most important basic circuits are Single-end feed (unidirectional feed), Figure 10.13a): Power is supplied to each feed section via a separate circuit-breaker. From the protection aspect, this type of circuit is easy to control. It is sometimes used for local-area railways and frequently in 1 AC 25 kV 50 Hz systems with crosscouplings. Double-end feed (unidirectional feed), Figure 10.13 b): At the ends of the feed sections of the respective substations, the contact lines are coupled together via circuit breakers or clisc:onnectors located in a switchgear housing. As has been shown in clause 10.3, double-end feeds reduce the voltage drops and power losses considerably. Double-end feed with cross-coupling( s}, Figures 10 . 1:3 c) and 10.13 cl). Cross-coupling the contact line installations of the two tracks further reduces the voltage drops and power losses. In case of a fault, all four circuit-breakers are tripped, meaning that both tracks of tlw sections lwtwern the substations will initially be isolated. After this, the disconncctors in tl1c\ cross-couplings are op<~rwd. If only one of the switchi11g groups has a permanent short-circuit or other fault, power is returned to tlw nnaffect.<~d sections approximat.<'ly one to t,vo 111in11tes aft,<~r the required testing and switching prncesses have h<'<)ll c,uried out, tlms pn111itting trains to rcs111nc rnuning on t.lrnt sedion
\ 10 Currents and voltages in traction power supply networks
554
a
~fl-H--------i:1-----:_ _[[:f:
1:P ,1:P '1:11
:
b
[:f: 1 [:f 1 [:f
1
r I [ I I I
I
!:f 1 i i r :k ,~:f~ - ~- - ~~-:--:~ -r~:-~~-;-~--:~if
, =f::j =t::h h
I I I I
I [
~:jl-r[i--:ii-Tr-T- Trr-1-dt~ 1
~:t:::::~
::::~:j~
3::ET: I
r--~::-?J I =¥4::f=
Figure 10.13: Basic circuits of contact line installations. a) single-end feed b) double-end feed with longitudinal coupling c) double-end feed with longitudinal and cross-coupling d) double-end feed with a large number of cross-couplings e) cross-connection circuit f) diagonal feed g) double-end feed with reinforcing conductors and one cross-coupling h) double-end feed with reinforcing conductors on one track only and with crosscouplings i) double-end feed with reinforcing conductors along part-sections of both tracks j) distributed feeds
Cross-connection of both double-end feed contact line installations, Figure 10.13 e): This circuit is characterized by the fact that both tracks are supplied with power from the substation via a common circuit-breaker. This circuit had to be introduced in contact line installations of railway lines with extremely high power demands in order to prevent too large potential differences building up at section insulators. Where potential differences of more than 800 V occurred at section insulators of 15 kV railway networks, arcing and overhead contact line disturbances frequently occurred when traction vehicles travelled across the section insulators. Cross-bonding the overhead contact lines in ~he vicinity of railway stations reduces the potential differences at the section insulators. Fault sel<~ctivity in cas<~ of disturbances is achieved by disconnecting the faulty basic sections. The time taken to do this hardly affects train trc1,ffic on those sections which are not faul Ly.
10.5 Contact line circuits ··-·· -··
·-------- _- ______________________5~5=5
ss line section feed branch
line section feed branch
u Ql 2
open stretch of railway line
insulated overlap
station
insulated overlap
open stretch of railway line
Figure 10.14: Line section feed branches with a station feed branch. • disconnect.ors closed m normal position 0 disconnect.ors open in normal position
Diagonal feed circuit, Figure 10.13f): Diagonal feeds with cross-coupling have the same characteristics as cross-connection circuits. This circuit is used for Berlin underground lines, for example. It can be modified by additional cross-couplings, these normally being located in stations or at other stopping points. Circuits with reinforcing feeder conductors, Figures 10. 13 g, h, i): The reinforcing feeder conductors are permanently electrically connected to the contact lin_e at specific intervals and may be installed parallel to both or only one of the contact lines of a double-track line. In practice. the variant shown in Figure 10.13i, which only has reinforcing wires in the vicinity of the substations, is also used. Distributed feeds, Figure 10.13.i): This circuit is frequently found in tram traction power supplies in the East German provinces and has proven its usefulness in these applications. The circuit is characterized by feed cables installed parallel to and connected to the owrhead contact line via cable distribution junctions as shown in the diagram.
10.5.3
Contact line installation circuits used by the Gerrnan railways, DB
The contact line installation circuit used by the DB is described in this section as a typical example of a.n AC traction overhead contact hne cfrcuit. A tvpical substat'ion supply section will include all overhead contact lines, feed conductors and bridging feeders, all being connected bv not more than two circuit breakers. Electric power is feel to a supply section from a distribution facility which may be either a .swdching substation or a switching post. A switching post. as explained in L3.3.1, is a l:i kY switching substation comprising more than one circ-uit-hreaker. The corresponding m·erhead contact line branch can supply pcrwer to line bro:nches, statwn bru:nc/1es or substztute feeder branches, as can be se<~ll in Figmc HL14. The boundaries of the substation supply sections are at tlw sectiouing overlaps or at the coupling points, as shown in Figure 10.15. In a longitudinal direction, the substation supply sections an• s11hdiYid<~d into S'U,bsections which can lw isola.t<'d dectricalh A distiuct.iou is rnad(• h<1t wcPn the s·u,bser:lions of OJJC"II. .st-rdclu:s of rnilwaY liu<' ,111d sub-sectums of slalun1s. The liom1cl;1r,v
_____ 10 Curreuts_aud voltages in traction power supply networks
5-56
a)
b)
c)
SSA
SS B
SP
SSA
I boundary of substation supply section I I I I I I
SSA
SS B
CP
d)
-0-
pole-mounted disconnector open
- - - pole-mounted disconnector closed
SSB
-0-II-
circuit-breaker OFF circuit-breaker ON
Figure 10.15: Overhead contact line circuits used by the DR a) Directional feed, longitudinal coupling via switching posts b) Cross-connection with pole-mounted disconnectors c) Cross-connection via coupling post d) Cross-connection via coupling post and neutral section (not used in new line constructions)
SS substation SP switching post CP coupling post
of a sub-sections normally coincides with the insulated ovedaps. At the same time it must be assured that the insulated overlaps is within signal coverage, i.e. that it is impossible for an electric traction vehicle with raised pantograph to come to a halt directly under the insulated overlaps. The distances lwtwer.n signal locations and the starting point of the first points as specified for standard overhead contact line designs is shown in Figure 6.17. In this illustration, the boundary of the sub-section is shown with the shaded area on the open-line side of the boundary. Station sub-section an~ further divided into individual swztchzng grn'/1,ps which are contact line sections that can be switched off, i.e. isolated individually. Usually, separate switching groups arC' sd up for main lines and secondary lines. In very long stations, the
1().5_ C:<)_uLact line circuits
main switching groups are even sub-divided longitudinalk Electrically, the switching groups are linked by sectfon insulators or insulated Oi'tT!aps. The latter are used especially where trains travel along the sections at more than 130 km/h, section insulators being not particularly suitable for such spe<'.ds. Disconnectors and switchgear are used in overhead contact line installations for the following purposes. section disconnectors link sub-sections, connector disconncctors connect auxiliary
Units: 1 Section disconnector, South or \;\Test side, on double-track lines the arrival 2 3 4
5 6 7 8 9 0
track, Section disconnect.or only on double-track lines - South or \;\Test side. departure track, Section disconnector, North or East side, on double-track lines the departme track, Section clisconnector - only on double-track lines ·· )Jonh or East side. arrival track, Cross-connector clisconnector, ( usuall~' with short-circuit signalling transformer), Loading siding disconnector. workshop shed isolator clisconnector (with earthing contact), Basic section disconnector of tracks on the station side \\ith odd section disconnector numbers, Basic section clisconnector of tracks on the st;uion side with even section disconnector numbers, Basic section disc-onm'ctor, ,, here required, preferably for special applications Substation section link switch, (onlv in conjunciiun ,,itli concsponding tens digits)_
558
10 Currents and voltages in traction power supply networks
Tens (in combination with the unit-digits described above): 1 to 9 Supplementary, serial numbers if required. For section disconnectors of arriving or departing lines odd-numbered tensdigits arc used in conjunction with odd-numbered units and even-numbered tens-digits are used in conjunction with even-numbered units for the throughgoing main line.
Hundreds: 1 Basic section disconnector, in cases where the tens-digits are not sufficient, 2 Disconnectors of operating facilities of open lines, 3 Special cases, e.g. private sidings, repair or vehicle maintenance sheds, auxiliary longitudinal sectioning, secondary connections to railway power systems, system conversion switchgear, special designations to prevent confusion etc., 4 Longitudinal disconnectors in stations, 5 Basic section disconnector, for secondary connections in stations, 6 to 9 As for 3. Code letters used to identify switches and circuit-breakers: A Protective neutral section disconnect.or, South or West side, Qn double-track lines the track with odd-numbered section switches, B Protective neutral section disconnector only on double-track lines South or West side, the track with even-numbered section disconnect.ors, C Protective neutral section disconnect.or, North or East side, on double-track lines the track with odd-numbered section disconnect.ors, D Protective neutral section disconnect.or - only open lines - North or East side, the track with section disconnectors, E Earthing disconnector (only for special cases, e. g. flood gate doors), F Disconnect.or for connecting basic sections to bypass feeder lines, G Disconnector for connecting main-line overhead contact lines to bypass feeder lines, L Connector disconnect.or for loading facilities Q Connector disconnector for third-party facilities, R Feeder disconnect.or of substitute feed branches with supplementary feed busbar on the outside, S Feeder disconnect.or of station feed branches and protective feed branches, T Disconnect.or for longitudinal subdivision of feeders, bypass feeders and connecting lines, U Feeder disconnect.or of line section feed branches, V Feeder disconnect.or connecting ovC'rheacl contact lines to connecting lines, W Connector disconnect.or for switch-point heaters Z Connector disconnector for train heating facilities. Figures 10.16 and HU 7 show ;-1, simplified basic section circuit diagram of a station on a11 electric railwav li1w nnd of' 01wrnti11g facilities of ll(~\\" line construction projects.
10.5 Contact line circuits
559
Gz 0 2
0
0
7
0 motor-operated pole-mounted disconnectot
L::,. manually operated pole-mounted disconnector Figure 10.16: Simplified basic section circuit diagram of a station. 508
8
a)
overtaking station 402
4 1
401
9
b)
509
A-shaped cross-over section ,W(3)
5$(15)
fjj
ft]J(5)
@_(1)
§
w<2) V-shaped cross-over section
c)
(!z(1)
(3)_(4)
¢(2)
Figure 10.17: Simplified basic section circuit diagrams of cross-over sections and overtaking stations on new line projects. a) overtaking station b) A-shaped cross-over section c) \!-shaped cross-over section I
o a
I
.l !
I I
560
10.5.4
10 Currents an~!_ voltages in traction power supply networks
Disconnectors
The junctions between basic sections in the DB railway network are bridged by disconnectors. These are capable of interrupting currents of up to a certain magnitude and number of switching cycles. Therefore, it is advisihle to switch them with no or only low load.
10.6
R,eferences
10.1 Petterson, G. A.; Swenson, S.: Storungskompensation
10.11 Measuring record taken at 10. May 1993 by the company Fischer & Ehms KG. 10.12 DR-M 23-03,()01: Bal111<)11crgievcrsorgung 750 V Gleichst.rom, Resistarrnen und Konduktanzen (Power energy supply with DC 750 V, resistances and conductances) Berlin, 1990. 10.13 Spravoc:nik po ek)ktrosnabzcniju zelezuych dorog. (Hand book for electrificaiton of electric railways), Verlag Transport, Moskau 1980. 10.14 Kie13Ji11g, F; Schneider, E.: Verweuduug von Bahnstromriickleitern an dcr Schnellfahrstreckc Madrid-Sevilla (Use of return conductors at the high-speed line MadridSeville). In: Elektrische Bahneu 92(1994)4, pp. 112 to 116. 10.15 Put;z, R.: Uber Streckenwiderstande und Gleisstrorne bei Einphasenwechselst;rombahnen (On line resistances and track currents for single phase AC lines). In: Elektrische Bahnen 20(1944) pp. 74 to 92. 10.16 DR-M 21-04.001: Bahnenergieversorgung 16,7 Hz, Netzberechnungen fiir Anlagen iiber 1 kV, Impedanzen (AC 15 kV 16,7 Hz power energy supply, network analysis for installations above 1 kV, impedances). 1983. 10.17 German Railway: Streckenimpedanzen der Neubaustrecke, Messwerte impedances of new high-speed lines, measuring records) Munich, BZA, 1987.
(Line
i
'I
I
10.18 Zimmer/;, G.; Hofmann, G.; Jecksties, R.; I<.raR, R.; Schneider, E.: Ri.ickleiteroberleitungsanlagen auf der Strecke Magdeburg-Marienborn (Return conductor installations on the overhead contact equipment of the Magdeburg-Marienborn line). In: Elektrische Bahnen 92(1994)4, pp. 105 to 111. 10.19 Information provided by SBB Swiss Federal Railway 10.20 Feydt, M.: Vorschliige zur Verwendung der Kabelmantel, metallener Rohrleitungen, der Gleise und der Erdseil-Maste-Kettenleiter als nati.irliche Erder (Proposals to use cable sheeths, metallic pipelines, tracks and earthwire pole iterative network as natural earth electrodes). Report of the institute for energy supply Dresden, 1982.
i
10.21 Hellige, B.; Hampel, H.: Untersuchung des Ubergangswiderstandes von Straflenbahngleisen (Investigation of the transition resistance of tramway tracks). In: VESKInformat;ionen, Dresden 5(1971)4, pp. 28 to 34. 10.22 Zimmer/;, G.: Bericht iiber Ableitungsbeliige moderner Oberbauarten (Report on the leakance of modern superstructures). Frankfurt, 1993. 10.23 Nitscli, K.: Ergebuisse der Uutersuclmngen des Isolationswiderstandes von Stahlbetonschwclku (Results of investigations of the insulation resistance of steel reinforced concrete sleepers). Iu: Signal und Scltieue 10(1066)9, pp. 376 to 383. l(L24 A/x,J, ,L Die Auswirkuugeu der Schaltltandluugeu bei Streckenschaltern von Gleichstrombalmen rnit Strnmschieuen untr)r liesondcrer Beriicksichtiguug der Vorgange in deu Schicucn und i111 Erdreich (The dfocts of switching operations at circuit break<\rs of DC railways using conductor mils wit.It special co11sideratio11 of the processes het.w<~<~tt rails ,utd earl.It). HIV Dresdc•n, l~HiD, dissc\rl.atio11 thesis.
I,
562
10 Currents and voltages in traction power supply networks
10.25 Kleitz, F.: Elektrische Eigenschaften von Fahrleitungen elektrischer Bahnen (Electrical characteristics of overhead contact lines of electrified railways). HfV Dresden, 1981, thesis for diploma. 10.26 Milz, K.: Elektrifizierungssysteme for den Hochgeschwindigkeitsverkehr (Electrification systems for the high-speed railway traffic). In: Elektrische Bahnen, 89(1991)11, pp. 323 to 325. 10.27 Schmidt, P.: Berechnung der Spannungsabfalle zweigleisigerelektrischer Bahnen bei beliebiger Anzahl von Querkuppelstellen (Calculation of the voltage drops on doubletrack electric railways with any number of cross-coupling). In: WZ der HfV Dresden, 22(1975)2, pp. 401 to 427. 10.28 Schmidt, P.: Energieversorgung elektrischer Bahnen (Power supply of electric railways). Verlag transpress, Berlin, 1988. 10.29 Brodkorb, A.: Ein Modell der elektrischen Bahnbelastung auf der Grundlage der digitalen Simulation der Zugfahrten (Modelling of elctrical railway loads based on digital simulation of train runnings). HfV Dresden, 1986, thesis for doctorate. 10.30 Biesenack, H.; Hauptmann, A.; Muller, K.; Schmidt, P.: Bahnbelastung und Spannungshaltung im Hochgeschwindigkeitsverkehr (Electrical railway load and voltage stability in case of high-speed traffic). In: Elektrie 50(1996)9-11, pp. 324 to 333. 10.31 Stephan, A.: Berechnung und Bewertung der Belastung von Traktionstransformatoren im Hochgeschwindigkeitsverkehr (Calculation and assessment of loading of traction transformers for high-speed traffic). TU Dresden, 1995, dissertation thesis. 10.32 Schuhmacher, R.; Scherrans, Th.; Stephan, A.: Auslegung der Bahnenergieversorgung der Mannheimer Verkehrs-AG for den Stadtbahnbetrieb (Design of electric p~wer supply of city rail operation of Mannheimer Verkehrs AG). In: Elektrische Bahnen 95(1997)5, pp. 131 to 138. 10.33 DB: German railway directive Gbr 997.0102 - Overhead contact lines, planning and construction of overhead lines. 2001.
11 Current-carrying capacity arid protective provisions 11.1
Current-carrying capacity of electric traction contact lines
11.1.1
Electric traction power load
11.1.1.1
Power requirements
The power requirement of a railway results from the physical power necessary to fulfil the transportation purpose. The transportation process itself differs greatly over time and is also dependent upon the geographical location. The physical power required to achieve a specific line transport need, depends on many parameters. The most essential are: - the speed, the power required being proportional to the cube of the speed, - the train weights, the frequency of servfre, the line gradients, the frequency of restarts, the availability of regeneration braking systems, and the driving style of train drivers. To achieve an optimum design for contact lines, the characteristics of traction loads have to be determined sufficiently accurately and described. 11.1.1.2
Railways for general traffic
Railways for general traffic are, from the railway engineering aspect, characterised by the fact that trains of various categories use the line at speeds of up to 200 km/h resulting in power demands per unit length of up to approximately 300 kW /km. Their load distribution charact<'ristic can be described with the aid of stochastic variation functions [11.l]. The c-o111ponents of the idealised random functions describing the loads on main line rmlwo.ys for general traffic are shown in Figure 11.1. The graph a) in Figure 11.1 shows the variation in 1nonthly rn,eu:n load values of a substation in the course of a _\·ear. The annual load variation pattern is determined, for example, by the rn'('d to heat passenger trains in the winter, by holiday traffic in summer months or b_\· other seasonal mass transportation demands. For design calculations. the statistically determined day '.c; load coefjicierd cc1 is important. The day's load rnef!icient is (1 L 1)
___________ __________ ____
564
:;_:_
___
____ 11 Cll_rrent~carrying capacity and protective provisions
"O
cu
_Q C
cu Q)
2 January
April
June
0
6
12
Oktober
,January_
b)
"O
~ C
cu Q) 2 18
Time 24
Period _ _ _ __..,_
c)
t
Q
al _Q Q)
C
.::J
0
15
45
30
min
60
Period _ _ _ __..,_
Figure 11.1: Components of the idealised random functions describing railway line loads. a) Variation of the monthly, weekly or daily mean values Pc1 in the course of a year b) Variation of the hourly or half-hourly mean values Ph in the course of a day c) Load variation within an hour, presented as a random distribution Pi annual mean load Pc1 daily mean load
2,0
I
\\
1,8
\
1,6
\
.c
(.)
J'
c
1,4
"'- I"--
Q)
0
:E Q) 0
1,2
I"'.
~
ch r--- i--:.:_ r---_
--
r--....
0
<.,d
1,0 0
2
4
6
8
10
12
14
Annual mean load Pi---------
16
MW 20
Figure 11.2: Day's load coefficient cd and hour's load coefficient C:1t as functions of the annwtl mean load I'j, as given in [11.l].
I
/\
where Pc1 max is the maximum daily average load occurring in the entire year and Pi is the annual mean load. Experience has shown that the day's load coefficient is virtually only dependent on the annual mean value. Figure 11.2 shows the relationship between cc1 and Pi. The graph b) of Figure 11.1 shows the typical variation in the load values of a main line substation in the course of a day. It is characterised by clear peaks of rush-hour traffic in the mornings and evenings and by low-load periods at midday and at night. By statistical evaluation of a large number of implemented installations, it is also possible to determine an hour's load coefficient c 11 . hour's load coefficient is defined as (11.2) In this equation, P11 is the maximum hourly mean power consumption during a clay and Pc1 is the corresponding daily mean power. The hour's load coefficient too, is also only dependent on the annual mean power. This relationship is also depicted in Figure 11.2. The variation of the power load within an hour represents the sum of the respective loads occurring on the system due to the individual trains travelling on the section of line under consideration at the time. This power load can be described as a random function. Using equations (11.1) and (11.2), the mean value of the power of a feed section during the hour with the highest load within the entire year, Ph max, is (11.3) The mean annual load Fj can be calculated from the total annual energy consumption l!Vj of the section. From an engineering aspect, the use of these idealised components makes it easier to describe the load as a random function. The same is true for tram way line loads [11.2]. In many cases, it is even possible to describe the traction pmYer load as a variable which is not dependent on time. In the case of feeds used to supply power directly to the contact lines, it is also possible to describe the currents for high loads as non-timedependent variables. It is acceptable to assume that the traction power loads follo,v a normal di.,tri:lndion function, where Ph max is the mean value of the distribution and ap the standard deviation. With this hypothesis, it is possible to forecast the probability with ·which the load p will remain below a specified value Pc1c1: 1
ar
pdd
~
I [ (p
21r -00
exp -
Ph rnax) 2 /2 CTP')] dp
(11.4)
The probaoility of P(p < Pc1c1) can be expressed in this simplified form because it is true that Ph max « ar > 0. Equation (11A) is also called the distribution function of the random variable p. If the standard deviation aP is expressed in terms of the coefficient of" V
11 Current-carrying capacity and protective provisions
566
and the power limit Pc1c1 as the sum of the mean value standard deviation ap:
Pi
1 max
and a multiple of the
(11.6) Equation (11.4) can be transformed in to the standardised form of the distribution function F ( Ac1c1), being the Gaussian 8tandard error function
1
J2ii
>-c1c1
j
exp(->? /2) cl,\
(11.7)
-oo
This standardised form of a distribution is described in tabular form in all relevant publications on statistics. If P(p ::; Pc1c1) or F(,\1c1) is the probability of a random load remaining below the given limit value Pc1c1, as discussed above, the converse (11.8) can also be deduced as the probability of occurrence of a load which exceeds the limit Pc1c1. In electrical energy engineering, this function is called the continuou8 loading diagram or standardised loading diagram. Assuming that the described distribution function is a valid representation of the frequency of certain observed loads, this would mean that within a given period T, the load occurrences will remain below the limit Pc1c1 with a frequency of (T-t)/T = F(-Ac1c1) and conversely, will exceed the limit Pc1c1 with a frequency of t/T. Therefore, it is concluded that the relationship
P(p < Pc1c1) = (T - t)/T
(11.9)
exists between the probability P(p ::; Pc1c1), calculated from the standard distribution, the observation frequencies t/T of load occurrences exceeding the limit Pc1c1 and (T t) /T of load occurrences remaining below the limit Pc1c1. In statistics, the hypothesis that the calculated probability corresponds to the observed frequency of occurrences is called the ergodic hypothesis and applies to the traction power load of general railway traffic. Figure 11.3 shows the measured continuous loading histogram l - Hm (i) and the theoretical continuous loading graph 1 Hm (i) cleri ved from this, as well as the distribution function H(i) of the load current of a railroad traction substation. To illustrate the explanations given above, Figure 11.4 shows the density function of the standardised normal distribution. Figure 11.5 shows the coefficient of vanatfon vp in relation to the mean annual power con8umption Pi of main lines and in relation to the mean current value in a DC 600 V railway traction system. The relationship shown has been determined empirically from a large number of measurements taken in several European railway networks [11.3]. For thermal design considerations, it is assumed that the current occurring during the hour with the maximum load also fiows over a longer period. As a good approximation, the load current that is of interest in this case can be expressed as
I = I' I (u . cos ,p) .
(11.10)
11.1 Current-carrying capacity of electric traction contact lines
1,0
,---._ /
1'
1
1'
l'l
l \J
Q) ()
C
~
'I
0,6
'l
::, () ()
0
0
I
0,4
I
g
I
e
0,2
'l 'l 1-
N
0...
/
~
/
1-H(i) ,..__i,--1-Hm(i)'"--L I
-----100
0
Figure 11.3: Empirical 1 Hm (i) histogram and theoretical 1 - I-Im (i) continuous load curve, as well as the cumulative distribution curve H(i) of a normally distributed load current drawn from a standardised substation.
l
I
(0
.0
''I
I
/
i
I
]5
I
L.-,---
I/
1'0,8
567
200 300 400 500 Current i - - - - - -
600
A 700
)( Q)
:0 (0
-~ 0,2 +---+----+---H-----+--+---l--1----+-----I 0
;~
I ~~
-~ 0,1 +---+----+~t----+----+--+----+---\----+-----1 Q)
0
µ-3cr
µ-cr
X;nf
µ
µ+cr
µ+3cr
X sup
Variable x - - - -
i ,0
\
10,8 I
\
I\
0,6
C
0
'iij
~
~ 0,4 >
I"-. .........
0
cru
u
Figure 11.4: Density (for a= 1) of a quantity (power or current) with a normal distribution for a substation and T = 1 h. The mean value is 11 = Ph.
r-- r--
0,2
i---
i= Q)
-
0
u
0 0
0
2
1000 600 V level
4 6 8 Mean annual power
2000
A
4000
10
12
MW
16
Figure 11.5: Coefficient of variation vp as a function of mean ,urnwd power consumption.
__ ll
568
Cunei1t_-_ca.rryi11g capacity ..i:nd prot.ective provisions
Table 11.1: Load p<'.aks of duration t, withiu a load observation period T 1 h in a total of quantities normal distribution.
I.
3 min 1 min 10 s
1s
(T
1)/T
= F(,\1c1)
0,9500 0,9833 0,9972 0,9997
>-c1c1
1,645 2,13 2,77 3,44
If, for example, the mean annual value of the power Pi, easily determined from the annual energy requirements, is known, the current occurring in the hour of maximum load in the course of an entire year is
h
max
= Cd
· C1i ·
Pj (U · COS
(11.11)
·whereby
U cos
rated voltage of the traction energy supply network, and mean value of the power factor in the traction power network.
To estimate the load peaks of a defined duration within the maximum load hour, the peak values corresponding to the Add values are taken from Table 11.1, which is based on a normal distribution function for F(,\dd) = (T - t) /t, in relation to T = 1 hour. This can be illustrated by the following example.
Example: The mean annual line load of a heavily loaded feeding section is Fj = 3 MW. What are the peak load currents in this feed section, given the voltage U = 25 kV and cos
.As explained previously, the basic value for determining traction power load is the continuous load characteristic:, i.e. the probability 1 F(1\c1d) of limit values being exceeded. In ac:corclanc:e with the rule used to calculate these loads, the load values of a defined duration occurring within a reference period T are sorted according to magnitude, beginuing with the maximum value, as shown in Figure 11.3. In reality ho\\'ever, periods ,,,ith lower loads occur betvveen the individual peak load periods. The
569
1!:LQ~~Ecmt-carrying capacity of~~e_ctri_c traction contact lines
a)
Headway 6/7 min
Headway 14/15 min
2,0
2,0 Branch 1
kA
l
1,5
I
1,5
1
1,0
1,0
c
c
e:' 0,5
0)
~
=i u 0,0
0,5
0
0,0
t_:
I
I I I I I I i
/\
l/
Time window of variable width Branch 1
I
I I ' I
~i/:
~ / "'-, _r "'l
b) 2,0 Branch 2
1¥,
1,5
IL n I l'--1
~
1,0 I--'
i
Branch 2
kA
I-
~
fV
0,5
J
1'---
l ._,I
fv fV
1,0
c
e:'
=i u
0,5
=i
u 600
0,0
1200 Time
1800
s
2400
3600
0,0
600
1200
t --------
1800
s
2400
3600
Time t - - - - - - -
c) 2,0
2,0
kA
kA
1,5
-
-
~~
1 c
1,0
~
=i u
::::-
1,5 Branch 1
---
I'
i
1,0
--
0,0
10
100
Time window width I
1000
s
10000
I
11~
!iii I'-
j-iII r- - -',
Branch 1
~
jli
1:1
:j
1111
ii ii
e:' 0,5
0,5
I
\11
I
c
Branch 2
I
u
!ii 0,0
10
Brrf11[111
100
Time winoow width
1000
s
10000
t
Figure 11.6: Load currents of two branch lines of a substation along whith high-speed trains drawing traction currents of 1130 A travel at constant speeds of 330 km/h [11.4). a) calculated i(t)-time dependent pattern feeding branch 1 b) calculated ·i(t)-time dependent pattern feeding branch 2 c) time-weighted equivalent continuous load curves for these currents
loads which cause heating of the equipment in operation are somewhat lmver than the loads calculated b~· this method.
11.1.1.3
High-speed and heavy-duty railway lines
I--hgh-speed and heavy-duty railway lines, e.g. underground and metropolitan railway lines ,vith short headways between trains, have totally different traction power load characteristics to those of general railway traffic. These types of railway are chara.cterised by an impulse-like load on contact line installations, feeds and substations. Studies have shmn1 that the specific energy demand of high-speed railway lines can be as high as 1 to 1,:3 MvV /km and that of heavy-duty railway lines even as high as 1,7 i.o 2,fl :\[W /km, both cases iU<) valid for double-track lines [11.4]. Figm<' l LG shmvs the load currents of supply sub-sections of a substation 011 a highspeed railwm, line The high-speed trains draw tr;-ictio11 cmT<'nts of l 1:30 A at collector
11 Current-carrying capacity and protective provisions
570
strips, travelling at constant speeds of 330 km/h. Ou the left-hand side, the graphs of the contact line currents are shown for a case where all trains travelling in one direction pass at 6 minute intervals and trains travelling in the other direction pass at 7 minute intervals. The right-hand side shows the corresponding load current curves for 14/15 min intervals. Accurate calculation of the thermal stress on overhead contact line installations subjected to currents represented by i(t) requires considerable effort. However, if a timeweighted equivalent continuous-load curve [11.5] is used, realistic modelling of the effective currents determining the thermal stresses is relatively easy. The time-dependent characteristics of the currents are not lost in this form of depiction [11.4]. In the following discussion, modelling of the time-weighted equivalent continuous load curves is first described for the arithmetical mean values: The real time graph of the load current i(t) within a reference period T forms the basis. This is usually available in the form of a time-discrete sequence of values with a defined time interval tn as shown in Figure 11.6. The next step is to define a time window t*. This variable time window is moved across the entire load current graph in steps of t 0 , starting at t = () and ending at T - t*, cf. Figure 11.6. The mean load current is then calculated for every possible position of the time window of width t*. The maximum mean load value I max subsequently determined is stored in conjunction with the current window width. This is repeated with varying windmv widths ranging from the smallest possible value, i.e. tn, right up to the largest possible value i.e. t* = T. Consequently, we obtain a function of the ma.ximum mean loads in relation to the load duration as represented by the window width, which can be called the time-weighted equivalent continuous load curve of the means values. In reference [11.5] this is also given the designation "peak value graph". For discrete-interval load current value sequences i(t) related to a time interval of tn, the rule for calculating the time-weighted equivalent continuous load curve of the arithmetic means is
Imax(t*)
t+t*
max
(
:
t
L IIvl · to v=t
)
For the heating characteristics and thermal load calculations however, the effective values of the load current are decisive. The effective current value, which is the rootmean square value of the current, corresponds to the equivalent direct current which would generate the same heat in an electric resistance over a period T as the timevariable current under consideration. The general equation for the effective current value is: leff(t)
=
l {T T Jo I(t) 2 · dt
The modelling rule for calculating the l,ime-,,·<\ighted equivalent continuous load cune
11.1 Current-carrying capacity of_
571
traction contact line
track
Figure 11. 7: Single-phase earth short circuit.
of the effective values is analogous to the arithmetic mean values. For a given timediscrete sequence of load current values, the equation is : I,ff ma,(t')
= max
(
1 t+t· 2 ) t* ""' L_,, 1V · to
(11.12)
11=t
where O :S t :S (T t*) and tD :S t* :S T. The part b) of Figure 11.6 shows the time-weighted equivalent continuous load curves for 6/7 min headway (on left side) and for 14/15 min headway (right side). These were calculated using the above algorithms. The standardised equivalent continuous load curve for general traffic railway lines and the time-weighted equivalent continuous load curve of high-speed or heavy-duty railway lines, form the basis for rating the thermal load capacity of contact line installations.
11.1.1.4
Short-circuit loads
Short circuits in traction contact line installations are caused by damage to or faults in the insulating components installed between conductive components having different electric potentials. The main reasons for faults are aging material and physical damage to insulating components as well as overvoltages and pollution deposits leading to insulation breakdown or arcing. Dead short circuits are most frequently the result of operator errors, e.g. not removing earthing and short-circuiting equipment before switching on the power supply, or electric traction vehicles entering earthed contact line sections. Short circuits lead to high mechanical and thermal stresses in the affected electric installations. Energy supply cuts and dangerous situations may result. To select the components, especially circuit-breakers and set up protective equipment correctly, it is necessary to know the magnitude of the expected short-circuit carrents. Short circuits in railway installations can also induce dangerous voltages in cables and metal structures parallel to the railway line. In a traction contact line network, any earth connection will constitute a short circuit, as seen in Figure 11. 7. The short-circuit current in single-phase AC railway traction systems can be calculated using the formulae in Table 11.2. In the 16,7 Hz traction pmver supply network of the Gennan railways (DB), the following maximum shortcircuit currents have been observed: up to c!S kA in centrally fed sections, and up to 20 kA in 11rn1-ce11trally fod sections.
,l I,
,_·1,_ ,1
!Ii
!,;"
ri, 1i:j:
I
(J,'
11 Current-carrying capacity and _prot(~ctive provisions
572
Table 11.2: Clw.racteristic va.liws of short.-circuit currents according to standards EN 60 8651-11.94. S:nnbol
Ddiuitiou
Formula.
I"k
I{:=
'/,p
'ip
Ia
Ia
lie
lie=,\· I;'c
It11
lt11
S"k
S{; = Un · I1~'
C.
Un/ zk
= "; . ,/2 . I{: /J..
I{:
I{;· Jm + n
I)
2)
:J)
•I)
5)
6)
or
S/: = v'3 · Un · I{: 1)
C
zk 2)
K,
3)
µ
4)
,\
5}
rn,n
I,c 6) 7)
7)
Initial symmetrical short-circuit current: clfoc:tive (nns) value of the symmetrical alternating componeut of a short-circuit current at the moment the short circuit occurs if the short-circuit impedance remains constant and equal to that existing at time t = 0. Peak short-circuit current: maximum absolute value of the expected short-circuit current. Symmetrical short-circuit breaking current: effective (rms) value of a short-circuit alternating current at the moment the circuit is opened by the circuit-breaker. Sustained short-circuit current: effective (nns) value of a short-circuit alternating current which would remain at a constant value after all transient processes have decayed. Thermally equivalent short-circuit current: the effective (rms) value of a current which would have the same thermal effect in the same time as the actual shortcircuit current which might have direct-current component and decay with time. Initial symmetrical short-circuit AC power: the product of the initial symmetrical short-circuit current and the nominal voltage. These quantities are not quantities of power in the physical sense, only factors used in calculations.
Voltage factor = 1,03 to 1,1 in railway networks Network short-circuit impedance Impulse factor according to Figure 11.9 [11.6] Decay factor according to Figure 11.10 (11.6] for AC 16,, Hz, p = 1 for AC 50 Hz Factor for calculating steady-state short-circuit currents ac-corcliug to EN 60 865-1 Generator current rating Factors describi11g the heating effect of direct and alternating current compom,nts in accordance with EN 60 865-1 (n ~ 0,95 in the central\\· feel railway network) in railway traction power networks in three-phase AC power distribution networks
Due to the single end feeding used, the short-circuit currents in 50 Hz traction power networks are noticeabl:v low<,r than those in 16,7 Hz networks using double encl feeds. Figure 11.8 shows the 1uaxi11rnm short-circuit currents of a 2-l km long high-speed railway section with various overhead contact line configurations and different types of feeding, namely AC lG,7 Hz. and AC 50 Hz [11.7]. The double-ended feed used in 16,7 Hz overhead contact lines leads to noticeably higher short-circuit currents.
If the short-circuit nrn(•uts are ('.alculated using the fornrnlac given in Ta,ble 11.2, tlwn the values ohtain<'d ar<' ltiglwr than those obta.i1H'd Jiy n1<·as111('t11e11ts in ac-tua.l practice. In reforern·e [11.8]_ i! has been <'stahlislwd, ll\· prnliahilil.v-li,,sed nwthods of
- - - - ____5_7_3
30 ~ - - - - - - - - - - - - - , - - - - , - - - - - - . - - - - - - - kA
I I
~SA
I I
----~
1
~
2
c
3 : ·---·t
Q)
~ 15
I
_______ ,,
I
I
()
I
I
·s
I I
I I
5
210
0
t:0 "Vi
5
--~~---------~---------
4.
------~----~~: : : electrical isolation
5
I
0
3
I
I
+---------~'---~'-----r-'- - - ~ ~ - - - ' ~ · 0
8
5
16
12
20
km
24
distance from SSA
6
with s111>1>lementary feeders a!ld return wires with s111>plcmcntary foedern, without. return wires without supplementary foeclcrs, wit.It return wires \\ithout supplemental y feeders and return wires with supplementary feeders and return wires - without supplementary feeders and return wires
Figure 11.8: Maximum short-circuit currents in various power supply systems and traction contact line configurations (1, 2, 3, 4 for AC 15 kV, 16,7 Hz connected together; 5, 6 for AC 25 kV, 50 Hz). 2,0
1,8
\
1,6
\
\
I\
L.4
""
K
1,2
~
''------
r---.
1,0
0
0,2
0,4
0,6
0,8
1,0
RIX
o, g
1,2
Figure 11.9: Factor K. as a function of Rf X accordance with DIN VDE 0102, Figure 8.
111
- 1 - - - " t - - - ' " ' k - - + - - = - i . ~ = - - + - - - l - - - - + - - - - = i t =0 ,05s
1 ----=:cl:::----l t=0,05s 0,8 +----t----Ps:---+---+~4=---+---f-----1 t =0, 1s
l
t~0,1s
0, 7 +----t----t----l---~\----j~---+----+:,,.......---J t=0,25s
- - - 10-MVA single-phase generator - 40-MVA single-phase generator 0 25 0 5 -1---1-------1----+---+----+---J.-----l------l \ ~ ' s
0, 4 -r----1-----r---t------1~---+---+----+---, 3 2 5 6 7 9 8
Figure 11.10: Decay factor fl applicable to a 16,7 Hz railway trac:tion power network [I LG].
11 Current-carrying capacity and protective provisions
574
',
'
t
0,75 4---1-----1~1--+-=b\'-'-\-'--\-+-____ccC,f-\-\--------l---+-----+------l
I
~
:a ill ~
\
O5
1
- f - - - - - - - 1 - - - + - - - - - - - - t - -- , - + - - - - - , c - - - + - - ' " t r - - - - + - - - t - - - - - - - t
'
Q)
0
£
'.6 0,25 + - - - - + - - - - < - - _ _ _ , _ , , , - - - - + - _ - + - - - - ' - f - - - - + - - + - - - - - l co
D
\
0
' ' .....
0::
o+r,-,~-,-,+,-~,.,-,-,-,~~.,+,-,-~..-.-,+,..,..,.,.,,,,,_,.,_-,.,_..,.,...,....,.,...-,-,-,,.,..~...._,_,_.~..-M 4 16 kA 18 0 2 6 8 10 12 14 Initial AC short-circuit l'k
tan a=
Figure 11.11: Stochastic rating for short-circuits. a) design too weak b) optirnurn design c) design too strong
dik) max (di
1 c
Q)
~ 0
a
Time t - - - - -
Figure 11.12: Characteristic curve of short-circuit currents in DC railways.\
all factors that can be expected in real-life applications, that the real maximum shortcircuit currents are approximately 0,8 times the values obtained by using the formulae given in Table 11.2. The average short-circuit current values that can be expected are even lower. Figure 11.11 depicts an example for the cumulative frequency distribution of shortcircu,it currents. Reference [11.9] also explains an alternative method of calculating the expected short-circuit currents in electric railway traction pmver networks. In direct-current (DC) traction power systems, short circuits occurring in the contact ------ - line installation are relevant for the cresign ofEhe rectifier equipment. Such short-circuits have a characteristic current behaviour, as shown in Figure 11.12. The short-circuit impulse current Is is the main parameter affecting the dynamic short-circuit load. Thermal short-circuit loads are caused by the continuous short-circuit current Ik· In DC railway supplies without cnrrent in1.pv,lse .suppression chokes in the DC circuits, an Is/ h ratio of around 1,2 can he a.ssnmed as a good approximation. The absolute short-circuit currents in DC railw:-ty networks nre determined by many different factors and can be as high as 2G kA_
---------------
___________________
lLl Current-carrying capacity of electric t!·act.ion contact lines
1,8
- - - - -
--
~
km a
I
1,4
1 1,2 (/)
251,0 C
~
:::,
\
I
0,8
--- ~--"' <- ----
0
8 0,6
~
........ '' ......_ ~ ~ r--,.__ ........ ~, 1/ ' ' ~---"-----:: ' /
"
0
Q) 0,4
.D
~ z
SS Wittenberg SS L6wenberg SS Chemnitz mean value
\
~ /
575
_:__
-
--- --
- -
0,2 0,0
1985
1986
1987
i988
Year---
1989
1990
Figure 11.13: Frequency of short circuits
The steepest short-circuit c·urrent rise, (dik/dt)max, is the parameter used as a basis for determining the required circuit-breaker operating times. Furthermore, in DC railway networks, the minimum short-circuit current is an important factor in the adjustment of protective equipment. In practice, this current \ alue is calculated frequently, using the following approximation: (,1J:i-J.i:
hmin
=
(Uss - 0,15 · Un)/ Rioop
(11.13)
In this equation, Uss is the bus-bar voltage, which is usually assumed to be 1,1 times the rated voltage Un- R 100 P is the loop resistance of the contact line and track, and reaches its maximum value when the short-circuit occurs at the maximum possible distance from the substation. The duration tk of the short-circuit currents i:q traction power networks is determined by the response or operating time tK of the protective relays and the break-time tsA of the power circuit-breakers used. The following values may be used as guidelines for short-circuit durations tk = tK + tsA: tk ~ 10 to 25 ms in DC systems, tk ~ 20 to 45 ms in single-phase AC systems where vacuum circuit-breakers are used, tk ~ 45 to 75 ms in single-phase AC systems where compressed-air circuitbreakers and minimum-oil-content circuit-breakers are used.
In electric L·action contact line installations, short circuits occur quite frequently. C nder unfavourable conditions this may even lead to melting of the contact wire and/ or the catenary wire. In the German DB network, a frequency of roughly one short circuit per kilonwtre of double track lines per annum can be assumed. Figure 11.13 shows the fre111tency of 8/wrt-circuits observed in three diffr,rent substation regions over a five-year period. By also considering the frequency of tntins in lhese sections, it can be concluded that short circuits occur less frequently in sf~ct.ions with lower traffic than in those with heavier traffic. Dy comparison, only 0,02 faults per km line per annum occur in a cotuparahle 3"--'AC :30 kV 50 Hz power suppl\ network [11 10].
-576
- - ~ - - - - ~----·-
l_! Current.~~~·rEYi!1g capacity and protective provisions
In a traction power contact line network, every single-pho,.,e earth connection constitutes a short circuit which causes operation to be interrupted. However, less than five percent of all circuit-breaker trippings occurring in the DB's electric railway traction network are caused by s/;eady-sf;ate shod; cin:uits. The most important factors leading to the high annual freqw~ncy of short circuits in traction contact line networks are: third-party interforence e.g. - parts of loa,ds, such as wagon awnings, - birds or other animals bridging insulators, faults due to electric railway operation per se, defects on traction vehicles, - collector and pantograph damage, - switching errors in traction power network operation, meteorological factors, lightning, storms with strong wind gusts, condition of contact wire installations wear and tear, material defects.
11.1.2
Current-carrying capacity
11.1.2.1
Introduction
The loads on contact lines due to currents have been analysed and discussed in the preceding section. To withstand these different types of load, the contact line must have a certain current-ca:rrym,g capac-ity to withstand thermal loads. This is also termed thermal resi.,f;ability or thermal loading capability. The continuous current-carrying capacity characterises the thermal withstand resist.ability of contact lines and is used to compare the capability of contact lines. As described in clauses 11.2.4, 11.2.5 and 11.2.7 the electric loading is not continuous but represented by time-dependent values. Therefore, also the current-carrying capacity should be presented by corresponding parameters.
11.1.2.2
Differential equation describing the heating of contact wires [11.1]
The electric current causes a temperature rise of the conductor compared with its environrnent. The co11d11ctor dissipates heat by radiation and convection to the environment. The r;--vlicttiou of th<~ sun also heats the conductor. Three processes can be clistingu islwcl: OJH~rational c11:1ren,/,~ varying ,vithiu minutes clue to starting and braking vehicles ( see clause l] 2 2) r:ontin:11.ous c11.11cnJ,,; (s<:<~ cla11SC' 1 l.2.4) and sho'l'!> r:i·rtu:t,/, 111.11·1:11 Is ,vi th cl urn t ious of 1n ill iS<'COil( ls onlv (s<·<~ clause 11. 2. 5) with011 t. <',teui;i\ l1<·,lt <·,ch,rng<',
________________577
} l_}__Q_11_1:rent-carrying capacity of elecJELc:___t;__r:c~c:_t~i~!~--l~o~1tact lines
::__:.____:_
dP,n
dPout
~
dt ~ ~x+dx
Figure 11.14: Joule's energy balance of a bare wire.
X
In case of constant currents and temperatures, there is a balance between input and output of thermal energy (11.14) where dPJ is the lo'Ule's heat, An the external energy input and Pout the dissipated thermal energy.
11.1.3
Current capacity in case of varying operational currents
11.1.3.1
Differential equation of contact line heating
Figure 11.14 shows the thermal energy balance of a bare wire with circular cross section. This can be used as a model for the thermodynamics of a contact wire. The thermal energy conducted into the volume element and the thermal energy conducted away from the volume element through the wire, can be ignored clue to the extremely high thermal conductivity of the copper. The Joule's heat generated by the current I flowing through the element is clPJ - 1 2
. (!20.
[l
+ etR(B -
20°C)]. (l/A). dt
(11.15)
In addition, the contact wire is heated externally by solar and diffuse sky radiation. Reference [11.11] gives the following equation for this effect: clPin - cl · E
·
P.~:> · sin c) · l · dt
(11.16)
P~:i
whereby E is the solar absorption coefficzcnt, is the solar raclzation intensity (ap2 proximately 950 \V /m in Central Europe) and c)· is the sun's declination, ,vhich depends on Lhe latitude tp, the angle ·1/1 of the line' relative to the North-South axis and on the ti111c of year. Solar absorption coefiicients are given in Ta.bk 11.:3. (11.17)
__________________ _ 11 Current-carrying capacity and protective provisions
'.:'._'._'.::'.__ 578
Table 11.3: Solar absorption coefficient of metallic surfaces, [lLll], [11.12], [11.13], [11.14]. Surface semi-polished matted, smooth oxidized, slightly dirty heavily oxidized heavily oxidized, dirty rolling-mill skin sandblasted rusty
Copper
Aluminium
0,15 0,24 0,6 0,75 0,85 to 0,95
0,08 0,23 0,5 0,7 0,88 to 0,93
Iron 0,45 1) 0,96 1 ) 0,65 0,67 0,61 to 0,85
1) Cast iron
hs
= 113,5° - l'PI
for cp ::; 23,5°
(11.18)
If the conductor material has a thermal capacity c and a mass density ry, the thermal energy stored in the conductor is
dPst =
C · "/ ·
A · l · (19
-
(11.19)
19air) · dt
where 19air is the ambient (atmospheric) temperature. The energy emitted by a conductor of circumference U due to convection and radiation is
dPout =
O'. •
U · l · (19 - 19air) · dt
(11.20)
The heat transmission coefficient a, which is explained in more detail in section 11.2.3, describes the fractions of heat energy emitted because of convection and radiation. This enables the heat energy balance equation of a conductor section to be written as: (11.21) The solution to the above differential equation is (11.22) where ,!9 1 is the initial conductor temperature, this not necessarily equal to the ambient temperature 19air· The term T is the heat'tng and cooling time constant and 19 2 is the final temperature. If the permiss1,ble .final ternpern,ture of the wire under consideration is designated as ,iJiim, the solution of the differential equation can be transformed to the following equation for calculating the value of a current !1,, which would heat the conductor to this temperature limit within a period t > 0 .
Q20 ·
[l + Cl'.n · (l'J1i1n
20°C)] · ( I
t/r)
(11.23)
579
In this equation, [}2o is the electrical resistivity at 20°C, O'.r the tcmperalu:re coefficient of resistance of the materials and ~~ 1 is the external specific heat energy applied per unit length. This equation enables the calculation of varying currents related to a time interva.l, e.g. for starting and braking procedures. A constant current that Hows through the wire, that is t -+ oo, that keeps the conductor at the limit temperature ·19 1i 111 , is called the design current or pennissible continuous current. The synonymous terms continuous current-carrying capacity or ampacity are used to describe conductor properties. In overhead contact line installations, the current fiowing through th<~ contact wire and catenary wire, as well as through any supplementary feed lines that may be installed, must be taken into account in thermal load calculations.
11.1.3.2
Parameters affecting the current-carrying capacity of a conductor
Heat transmission coefficient a The thermal energy lost P~ut to the environment per unit length due to convection and radiation per degree temperature difference is directly proportional to the heat transmission coefficient o: and to the circumference U of the conductor. The heat transmission coefficient a is the parameter that determines the heat energy transmitted from a conductor volume element to the surrounding medium. The heat transmission coefficient comprises a convection component (Ycon and a radiation component O'.rcI, i.e. (11.24) This permits independent study of the two components. The convective component of the heat transmission coefficient of an overhead contact line can be calculated using a method described in references [11.12] and [11.14]. This method uses the following parameters and relationships: ( 11.25) Nu = Nusselt number O'.con lw / A, Re Reynolds number = vlw/1/, (11.26) Gr Grasho.f n:umber, Pr Prandtl number, lw flow contact length of the conductor, in this case equal to half the circumference of the wire. For traction contact wires worn by 10 % lw = 0,0206 m for Cu AC-100 wires and lw = 0,0227 m for Cu AC-120 wires apply ,\ specific: thermal conductivity of air, I/ kinetic viscosity of air and v velocity of air Sl!notmding the wire. ks material property constant of air; ks = 1 · /3 · Pr/ 1/ 2 where /J is the coefficient of expansion of air measured in 1/K. Taking the temperature-rdaL<,.d material constant ks of air, cf. Table Jl. L Ute contact wire tempern.tllrc ·d< :vv and the ambient temperature /)air into co11sid<~1at.iou, the product is: 0
Gr· Pr - ks
l;~.
(Bew
Oai,)
(11.27)
11 CmTent~carnring_~a,p,u:ity and protective provisions
580
Table 11.4: Heat transmission coefficient of free conv<)ction and forced convection around Cu AC-120 contact wire, {)cw
oc 80 50 80 60 30
oc
>10- 2 W/(K · m)
10-u 111 2 /s
40 40 20 20 20
2,85 2,75 2,78 2,71 2,61
18,90 17,45 17,95 16,97 15,57
i?air
ks
/I
7
10 /(K · m 5,84 7,25 6,70 7,75 9,60
V
3
)
O:con tr
Cl!con f
m/s 0,36 0,21 0,42 0,36 0,16
W/(K·m 8,42 6,28
2
)
9,74 8,89 6,39
W /(K · rn 2 ) 12,8 12,0 13,4 13,0 11,1
The Nusselt number Nu of a contact wire can be calculated using this product. For
free convection, Nur
= 0,54 ·(Gr· Pr) 0 ' 25
5 · 102 < Gr· Pr< 2 · 107
(11.28)
The Reynolds number for free convection is
Rer = 6,97 ·(Gr· Pr) 01403 ,
5 · 10 2 < Gr· Pr < 2 · 107
(11.29)
The corresponding Reynolds number for combined free and forced convection with vw :S 1 m/s is (11.30) This can be used to calculate the Nusselt number Nutr for combined free and forced convection around a contact wire and a catenary wire as follows: Nutr
= 0,17 · Re~/ 2 ,
(11.31)
The reference temperature used to determine the air properties is taken to be the arithmetic mean of the contact line temperature and the ambient temperature: (11.32) These equations were used to calculate the convective heat transmission coefficients of an Cu AC-120 type contact wire for a range of contact-wire to air temperature differences. The results are shown in Table llA In this Table, O'.con r is the heat transmission coefficient for vw Om/sand O'.con tr is the heat transmission coefficient for an assumed wind speed of vw 0,5 m/s inside a tunnel. The value 'U in the Table is the speed with which air rises abme tlw lwated contact wire because of free convection. The values of v were calculated using equation (11.26). The rn,diation component: of thr heat h'ansmission coefficient, O:nt, is given by the radiant lwat tiansmission n~L--,tion postulated by Newton:
wlwr<' Ocw is the surfac-<' M('i\ radi,tting li<'at fnrn1 thP l1< al.Pd contact win' and ,dew and l'Jair are the contact wi1<' ,ul
ll}
581
Cunent-car~r,xJr~g capa'.:i~y of electric traction contact lines
Table 11.5: Heat transmission coefficients of Cu AC-120 type contact wire, worn by 10 %. Index f for vw = 0 rn/s, and Index tr for vw = O,G m/s. All values a given in W /(K*rn 2 ). {Jc:w
'!~ai,
O'.rd
O'.f
O:tr
80 50 80 60 30
40 40 20 20 20
8,72 6,28 9,74 8,89 6,39
12,8 12,0 13,4 13,0 11,1
6,55 5,68 6,00 5,44 4,68
15,3 12,0 15,7 14,3 11,1
19,4 17,7 19,4 18,4 15,8
oc
oc
reference [11.15] the heat energy
4
(T;iir/100)
4
(11.33)
]
In this equation, Cs 5,671 · W · K- 4 • m- 2 , the emissivity of a black body and -=ewair is the corresponding emissivity for radiation energy transfer between the contact wire and the surrounding air. Because of the radiative properties of the contact wire, which is diffusely reflective, and of air, which is transparent, it is feasible, to substitute the total emissivity Eewair by the contact wire emissivity Eew, which is solely dependent on the contact wire properties. By equating the expressions for Prd and
O'.rcl
= Eew
·Cs· [(Tew/100)
4
-
(Tair/100)4] /('fJew
,,Jail)
(11.34)
The ernissivity has a major effect on o, 1 c1. Within the course of the operating life of a contact wire, the emissivity changes continuously. The lower surface can be considered to be brilliant, the top oxidized and dirty. According to studies described in [11.16], the respective emissivities are Eew 1 - 0,24 and Eewu = 0,93. For a contact wire worn by 10 %, the ratio of lower to upper surface is 0,21 to 0,79. The expression for calculating the radiation heat transmission coefficient is
O'.rcl
=
0,21 . E-~:w1 + 0,79. Eewu . Cs . [ (Tew /100)4 - (Tair/100)4] 19cw - ,,Jair
(11.35)
Table 11.5 shows a range of radiation heat transmission coefficient values calculated using equation ( 11.35). I-frat transmission coefficient measmements on grooved con( act win\S of 100 mm 2 cross section at vw - 0 111/s gave values of approximately Ctcnn 0,2 W /(I<, m 2) and 2 n:rd - 3,8 W/(K · lll ) [1117, 11.18, 11.10]. Equation (11.3G) was ckdncccl 011 the basis of tlwse measmcrncnts . The equations ( 11.25) to ( 1l.Ti) were used to dd,cnni11e the lie.al. t.rnnsrnissioll cod!ici<'nt.s for grooved contact wire•:-;, sltown in T,d >I<~ l l Ji.
11 Currc11t-ca.rryir1g l:~1pacity and protective provisions
582
Table 11.6: Heat transmission coefficient for a contact wire of type Cu AC-100, all values given in W · m- 2 • K- 1 [11.l]. Ambient. temperature 'l?ai,
Contact wire tempcra.tluc 19c:w
Wind spend vw in m/s
oc
1
2
4
8
-20 70
34,6 36,4
50,4 52,2
75,0 76,8
116
0
10 70
35,4 36,8
51,0 52,3
75,0 76,4
115
20
30 70
35,8 36,8
50,9 51,9
74,3 75,3
113
40
50 70
36,2 36,8
51,2 51,7
74,1 74,7
111
oc
-30
Wind speed vw As explained previously, the heat transmission coefficient ex strongly depends on the wind velocity ( convection speed) vw. This fact is also demonstrated by Table 11.6. The following factors can be used to calculate the heat transmission coefficient of Cu AC-100 type electric traction contact wires with a satisfactory degree of accuracy [11.1) ex= 14,5 ex - 22
+ 14,5 · vw
for vw = 0 for 0, 6 S ·uw
< 4.
ex
vw
W /(K · m2 )
m/s (11.36)
Figure 11.15 shows the temperature rise graphs a.t, a constant current for a range of ambient temperatures Bair and wind speeds ·uw. Long-term meteorological records in Central Europe have shovvn annual average wind velocities at a height of 10 m between 3,5 and 5,5 m/s.
Ambient temperature '19air The German standards define 35°C as being the highest initial ambient temperature Bair· A 22 year series of hourly air temperature and wind speed measurements taken in Germany, comprising 192 864 pairs of values showed that a temperature of 35°C was exceeded lG times during this period, 3G°C was <'xceeded 9 times and a temperature of 38°C ,vas measured on only two occasions. Th<' wind speed exceeded 1,8 m/s at all tim<\S when temperatures of 35°C or above were obscrv<\
11.1 Current-carrying capacity of electric tractfon_.c:()nt,act lines
100
/_ I I /2I
K
90 80
1 70 0)
~
60
& Q)
:5 40
al
g 30 Q)
f--
0
~
--- 3
-
I--
-
-
/
,--- ~
II I /
co
10
I
l/1"
'6
-----
,
//
50
20
I
/1
Q)
0 C
I I
/
I11 //' I
1:1/ /'
5
-------
6
----------- ----------
, 11 0
5
10
15
Time
Permissible final temperature
min
20
Figure 11.15: Heating behaviour for a 10 % worn contact wire type Cu AC-100, operated at I = 600 A and P{n 1,2 W /m for a range of different convection speeds v-vv and ambient temperatures ·19air· 1 vw = 0 m/s, 79air = 40°C 2 vw = 0 m/s, 79air = -30°C 3 'V\V 1 m/s, 79air = 40°C 4 vw = 1 m/s, 19air = -30°C 5 vw = 4 m/s, 19air = 40°C 6 vw = 4 m/s, 19air -30°C
'19lim
Table 2 of EN 50 119 presented as Table 5.3 in chapter 5, specify that the rna:z:irrmrr1, working temperature of grooved contact wires is 80°C for electrolytic copper and 100°C for CuAgO,l and CuMg0,5.
Externally applied heat
P/n
Overhead contact lines and contact rails are heated externally by solar radiation and d~ffuse sky radiation. The surn of the effect of both types of radiation is called the global radiation. Representative surveys canied out in Germany [11.21] have sltow11 that the following values can be assumed for global radiation acting per metre 011 a coutact wire of type Cu AC-100: 1,2 2,3 6,1 8,2
W /m-annual average, W /m--in mid-summer at 100 % cloud coverage, W /m-in mid-summer at 50 % cloud coverage and W /m-in mid-summer with clear skies.
Measurements have sho\\'u that Lh<' temperatures of contact wJrcs without ('llrrent loads can be G K higher than th<' sutTotmding air in cases of cxtn\ttW heat radiation exposure. In the USA, U\mperatttrc difference values of 8 K han\ bcc11 nwasmcd on overhead power lines [11.22] . Figure 11. lG shows the t\ pirnl daih \·ariation of heat radiatio11 acting ou ,1 type Cu AC-100 contact wire in thC' su11uncr in Central Europe: the corn~spo11di11g \alues for a tvpe Cu AC-120 being 10 % ltiglwr Figme 1 l.18 sho\\"s how <'xtcrnnl <'ll<'rg,· applied to a wire affects its conti11urn1~; c11n<'11t-canying capacit,
I
11 Current-carrying capacity and protective provisions
584
· 9,6
800
W/m 2
W/m
700
8.4
600 ·
7,2
500
6,0
400
4,8
1 C
~
~
ro
.g
>, 0)
0
C)
3,6
300
C
Q)
s
Q_
C
200
2,4 -
100
1,2
0
0 6
9 min 8 7 6
8
10 Time
14
12
16
t
\\ ~,
' ' r---.7 ~ "''\:~' ---:
5
I¾~L"-.... ~ 5 - ' -- -
r 4
~-cc
::--_
~
2/ ~ ~ _/3 ~
3 2
0
18
Figure 11.16: Typical daily variation of global radiation in mid--summer as a function of the cloud coverage, showing the values of the resulting radiation heat per unit length acting on a type Cu AC-100 contact wire. o = hazy to clear sky O = 50 % cloud cover • = 100 % cloud cover
2
3
5 f!l s 6
4
Vw----
Figure 11.17: Heating time constants of a type Cu AC-100 contact wire as functions of the wind speed for various load currents I and ambient temperatures 19air· 1: J = 100 A; 19air = 35°C 2: I= 100 A; 19air = 20°C 3: I= 100 A; ·Dair= -20°C 4: J = 600 A; 19air = 20°C 5: I = 1000 A; 19air = 35°C 6: I = 1000 A; 19air = 20°C 7: I= 1000 A; 19air = -20°C
Heating and cooling time constant r If the density 1 , the specific heat c and the load current I are known, the solution of differential equation (11.21) can be used to calculate the time constant T as follows: C
·I. A
7-----------a · U - (1 /A) · CYR · I2 · Q20
(11.37)
It can be seen that a large rmmber of parameters affect this time constant. Figure 11.17 shows some time constants for the heating and cooling of a grooved contact wire in relation to the wind speed.
"\ ,'
1 Ll Cunent_:-canying <:,;,1pacityof electric traction contact lines __ _
585
Table 11.7: Continuous current-carrying capacities of conductors and contact wires without wear with solar radiation and wind speed 1 m/s at various ambient temperature, values given in A. Typ of contact wire Ambient temperature, °C Contact wire and conductor 20 0 10 -30 -20 -10 30 40 temperature, °C 624 CuMg AC-100 593 561 527 490 450 407 358 80 751 711 666 619 569 513 451 378 Cu AC-100 70 740 700 657 611 562 507 446 778 CuAg AC-100 80 782 739 693 645 592 534 469 393 Cu AC-107 70 702 CuMg AC-120 668 631 593 551 507 457 402 80 845 Cu AC-120 798 749 697 640 577 506 424 70 CuAg AC-120 876 833 787 739 688 632 570 501 80 Cu AC-150 976 922 865 803 738 665 583 487 70 BzII 50 404 385 364 342 318 293 265 233 80 BzII 70 487 463 438 411 383 352 318 280 80 BzII 120 704 670 633 594 553 508 458 402 80 734 Cu 95 693 651 605 556 501 440 369 70 Cu 120 848 801 752 699 642 579 508 425 70 Al 185 910 865 817 767 713 654 590 517 80 Al 240 1098 1043 986 925 859 788 710 621 80
1000 A
1
--------
800
Al240 Al 185 CuAgAC-120 Cu AC-150 -2:' 600 ·5 CuAgAC-100 C1l D. Cu 120 C1l 0 Cu AC-120 0) C Bzll 120 ~ 400 i-----t------t---t--=--t-----t---,'"-<-::::--"::~CuMg AC-120 m Cu AC-107 0 Cu AC-100 'E e:' Cu 95 :5 CuMg AC-100 u Bzll 70 200 Bzll 50
......D
- -
-30
11.1.3.3
-20 -10 0 10 Ambient temperature ,9 air
20
30 °C 40
Figure 11.18: Continuous current-carrying capacities of conductors and contact wires according Table 11.7.
Current-carrying capacity of individual contact wires or conductors
The nominal or continuous current-carrying capacity of overhead contact lines is the maximum constant current that an individual win: or the contact line can conduct indefinitely, without exceeding the maximum permissible or any other specified temperature for a given ambient temperature and wind vdocitv. Tlw continuous current.carrying capacity, ,vhich c;-rn be calculated for l ----0 (X) ll\· 11sing c'q11ation (1 L23) is also depr.ndC'ut 011 m;-uiy p;-u;.1.111et<'rs, as the respectiw ('
-·------- U Current-carrying capacity and
protective provisions
ble 11. 7 and Figure 11.18 show the continuous current-carrying capacities of indiual contact wires or conductors . . 1.3.4
Current-carrying capacity of overhead contact lines
th the methods presented above the current-carrying capacity of individual conducs in the steady state can be determined from equation (11.21) with reference to the it length and dP'
= 1 2 · f½ 0 [1 + aR ( fJ - 20°)]
(11.38)
m (11.15) for Joule's loss dP'In =
E ·
P.8110 • sin 6 · d
(11.39)
,m (11.16) for the energy input by solar radiation dP~utl
= 7f ·A· Nu· (fJ
(11.40)
fJair)
>m (11.19) for forced convection and the Nusselt number Nu from Nu= 0,65 Re 0 ,2
+ 0,23 Re 0,61
(11.41)
d the Reynolds Number Re according to (11.26). dP~ut2
=
S · E ·
4
d · 1r(T
-
T;ir)
(11.42)
)m (11.34) for losses by radiation. With this parameters the steady-state current or rrent-carrying capacity can be obtained from (11.43) (11.21) clPst = 0 was set for the steady-state. gure 11.18 shows the current-carrying capacity for some often used contact wires \pendent on the ambient temperature fJair· For the temperature f)lim of the contact ire 70°C is used. he current-carrying capacity IdoHL of an overhead contact line is the sum of the irrents flowing through the contact wire, the catenary wire and the parallel feeder 1e in the limit state. (11.44) he total current-carrying capacity of the contact li1w ldoHL is determined by the nnponent reaching first its thermal limit. 1 case of DC supply systems the individual portions on the total current depend on w conductance of th(\ cornporn:nts. /I (. \
Ht,01,/R.c:J\
(11.45)
11. 1 Current-canying, capacity of electric_ traction cont.act lines
587
Table 11.8: Current-carrying capacities of overhead contact lineR and conductor rails at various ambient temperatures, values given in A [11.23]. ,oaiivw m/s -20°C 0°c 20°c 35°c 40°c AC-100+ 0,0 635 560 473 396 367 50 BzII 0,6 919 811 685 573 530 AC-120 + 0,0 852 752 532 492 636 70 Cu 0,6 1234 1089 925 770 713 0,0 1347 840 1188 1004 778 2 * AC-120+ 70 Cu 0,6 1950 1720 1454 1216 1126 1616 1426 1209 1008 0,0 933 2 * AC-120+ 150 Cu 0,6 2334 2065 1751 1460 1352 2249 0,0 1983 1675 1403 1300 2 * AC-120 + 2871 2425 2032 1880 0,6 3257 2 * 150 Cu Conductor rails Fe 5100 0,0 4120 3708 3241 2835 2697 5622 5161 4513 3958 3755 0,6 Al 5100 7458 6711 5869 5148 4883 0,0 0,6 10548 9489 8298 7236 6905 Al 2100 0,0 4786 4306 3759 3302 3134 0,6 6768 6089 5324 4670 4430
For the total resistance applies
1/ Rtot
= 1/ Rew+ 1/ ReA + 1/ RFL
(11.46)
In case of AC supply systems the individual portions depend on the inductive coupling. In chapter 10 information is given on the calculation of current distribution in an overhead contact line. The distribution depends as well on the frequency. Table 10.10 contains information on current distribution for 16,7 Hz systems, Table 10.11 for 50 Hz systems. For the DB's contact line Re 200 with a parallel feeder line A.AC 240 the portions are for 16, 7 Hz Contact wire: new = 0,38; catcnary ,vire: neA 0,14; parallel feeder line nFL = 0,50 and for 50 Hz new = 0,38; ncA - 0,20; nFL = 0,44. The current capacity of the contact line can be obtained from
(11.47) where n1im is the portion of the component reaching at first its limit tempera.ture. Provided, that is the contact wire than
Table 11.8 shows cu,rrcnt-ca·n7ri'IUJ rnpacdics of overhead contact lines and conductor rails. The cunent-can_ving capa.cit,,· rnltws given in Table 11.8 have beE~n calculated using <~quations ( 11.44) and ( ll . 17). Th<) basic parameters applied in tlwsc cakulations arc the result of mcas11re111c11ts catricd out 011 co11tact wires . catcnary wires and contact wire damps [1Ll8, 11.rn. 11 2 l]. Talil<' lU) shows the c11rre11t-carrvi11g capacities of nmtact litH' t.yp<·s oft<'ll 11scd In· t.11<' DIL 0
588
.
··-·--····-·-··------
____!l Current-carrying capacity and protective provisions
Table 11.9: Current-carrying capacity of DB standard overhead contact lines at a wind speed vw = 1 m/s taking into account heating by solar radiation, all values' given in A. Stamla1cl
design Re200 Re 250 Re 330
Specified in [1L25]
·i91im
oc
Supplementary feeder
560 900 670 1270 850 1425
70 70 70 70 80 80
no yes no yes no yes
i?air = 35°C contact wire wear 20 % 10%
577 1133 686 1238 853 1553
'!?air = 40°C contact. wire wear 20 % 10%
529 1039 628 1133 801 1458
558 1127 665 1227 813 1509
512 1034 609 1123 764 1417
Note: The current-carrying capacity of lines using return feeders differs only slightly from the values given in this Table.
11.1.3.5
Current-carrying capacity of conductor rails
Measurements carried out on conductor rails made of AlMgSi0,5Fl 7 and with a crosssectional area of 3578 mm 2 show that the heat transmission coefficient for free convection, aeon, is approximately 5,3 W /(K-m 2 ). The radiation heat transmission coefficient, ard, calculated according to Stefan-Boltzmann's law for a conductor rail temperature of 85°C and an ambient air temperature of 40°C is found to beard= E-8,62 W /(K-m 2 ). The emissivity E of aluminium with a fresh extrusion surface is 0,16. Studies carried out with ACSR overhead power line conductors in industrial areas have shown that E was 0,4 when the conductor was newly installed, 0,6 after being in place for two years and as high as 0,8 after four years [11.26]. An emissivity of 0,75 to 0,85 can be assumed for steel conductor rails. In addition, measurements have proven [11.27] that there is always a certain amount of air movement around conductor rails mounted near ground level, through which a current is flowing. For a wind speed of O m/s, the heat transmission coefficient of aluminium composite conductor rails is assumed to be 9 W /(K·m 2 ) and iron conductor rails to be 12,2 W /(K·m 2 ). On the basis of considerations in which an analogy to the heating of contact wires was made, values of 18 and 24,4 W /(K-m 2 ) were assumed for a wind speed of vw = 0,6 m/s. These values were then used to calculate the continuous currentcarrying capacities shown in Table 11.8. Whereby E = 0,43 was used for aluminium conductor rails and a cross-sectional area reduction due to wear of the iron conductor rail by 10 % of the nominal value was taken into account. For comparison purposes, the continuous current-carrying capacity of an aluminium conductor rail with a cross-sectional area of 5100 mm 2 was calculated according to a __fi;irmula presented in [11.28]. The numerical equation states that fct
A
where, according to [l 1.28]: k:
=
!{ J • K2 · K:i
·
K, · /\:,
k 1
A mm
U 2
mm
(11.48)
11.1 Current-carryingcapacit.y of elec~ric tr·actitm C()Ilta<;t lines
contact line 4000
A
589
conductor rail 16 ,-.--~-,---,----,----,.-----,------.-,-------,
kA
1 3000 -.::;
c
[I:'
:5 2000 -- 8 u E
~
0
fii
1000
4
2
0,0 - - L - - - ' - - ~ - ~ - - ~ - ~ - ~ - - - ' - ~ - - - ~ 6 10 20 60 100 200 600 1000 s 3600 3 Period of action
Figure 11.19: Short-term current-carrying capacity of overhead contact lines and conductor rails. 1: Contact wire Cu AC-100 + catenary wire Bz II 50 nun 2 ; '131im = 70°C; ·i9air = 35°C; vw = 1 m/s and Id= 600 A 2: Contact wire CuAg AC-120 + catenary wire Bz II 70 mm 2 ; '13lim = 80°C; ·19ai1 = 40°C; vw = 1 m/s and I
1,01 K2 = 1,02 h . . ;3 1,07 K.1 1,02 J\."5 - 1,02 R'1 -
for K2Q - 35,4 n-l · mm- 2 · m, for '!9air = 35°C , for a temperature increase of 45 I<., for installation in the open, without forced convection, and for unpainted, clean track surfaces.
If the circumference U
-450 mm is inserted, a continuous current-carrying capacity of 4436 A is obtained. This value is lower than the value of 5148 A at vw = 0 m/s shown in Table 11.8 because the emissivity of a clean, brilliant rail ,vas assumed. The Berlin metropolitan railway has specified the permissible continuous current-carrying capacity to be 2800 A for iron conductor rails and 4700 A fm aluminium composite conductor rails, based on a maximum temperature of 85°C and an ambient temperature of 40°C, in both cases for a cross-sectional area of 5100 mm 2
11.1.3.6
Short-term current-carrying capacity and reference strength
The short-term cu:rT('.n/.-cu,rry·1:ng capacity Jr;, (t) is t.hC' term used to describe the maxitttum cm rent. permissil>lv for a given short period wit lion t the co11t.act wire or another curnpouent of au ovcrh<'ad lill<' <~quip11wnt c\xce<~ding the pern1ittcd temperature limit.
11 Current-carrying capacity and protective provisions
590
;;-'
~2000 -.
Figure 11.20: Reference current capacity JF(t*) ( time-weighted current-carrying capacities) of highspeed railway contact lines.
1: 2: 3: 4: 0
+---+---<--+-<-+-+-H+---+-+-H-++t-1+---+-H-++++H
10
100 1000 s Period----
10000
Re 250; vw 0 m/s; '19air = 30°C; P{11 = 0 Re330; vw = 0 m/s; '19air = 30°C; P{n = 0 Re 330; vw = 1 m/s; '19air = 40°C; P{n 2,8 W /m Re330; vw = 1 m/s; '19air = 40°C; P{11 = 2,8 W /m with 240 mm 2 aluminium supplementary feeder line
or reaching any undesirable condition. In reference [11.29] the operating range in the region of the short-term current-carrying capacity is called the "overload condition". Equation ( 11. 23) can be used to calculate the short-term current-carrying capacity of overhead contact line installations. Figure 11.19 shows graphs of the shortterm current-carrying capacities of overhead contact line equipment commonly used by the DB. These graphs also apply to systems operated at a frequency of 50 Hz. From the measurements carried out on the 3578 mm 2 co-extruded composite aluminium conductor rail described in the preceding section, a heating and cooling time constant of approximately 60 min can be deduced. If this value T = 60 min is assumed for conductor rails and inserted in (11.23), the short-term current-carrying capacity values It of conductor rails, also depicted graphically in Figure 11.19 are obtained. For high-speed and heavy-traffic railway lines, it is appropriate to model the currentcarrying capacity on a reference load variation which is determined in the same way as the time-weighted equivalent continuous load curve. In this load variation, it is assumed that an overhead contact wire or overhead contact line at ambient temperature is subjected to a current load for 10 seconds and heated to the permitted maximum temperature within this IO-second period. A constant current equal to the permissible continuous current then flows through the wire for the next 24 hours [11.4]. The currentcarrying capacity determined by this method is the time-weighted current-carrying capacity, also designated as the reference strength Ir"(t*) in this book. Figure 11.20 shows the reference loading capacity of two types of overhead cont.act line systems with and without supplementary feeder lines, typically used by the DB. '!91im
11.1.3.7
Short-circuit current-carrying capacity
In this clause, methods of determining the short-circuit current-carrying capacity of overhead eontact lines and their main components are explained. The short-C'ircuit current-carrying capacity, also termed short-circuit mpabilily or short-c1,rcuit rating, is important for the therrnal design cousiderations of ovnlw,td contact line installations. If iu equation (11.21) the value of the heat app!i(!d b:v (\X:t<·rnal so111TPS is ignored and it
11.1 Current-carrying capacity of electric tn1c_~on contact lines
----------
591
is assumed that no heat is dissipated from the wire because of the rapid rise of a shortcircuit current, then all energy set free by the short circuit will heat the conductor and, if the protective measures fail, the conductor might finally melt. If the value dP1 = dPst is assumed, the solution of the differential equation provides a formula for calculating the short-circ'il,it cmTent-carrying capacity h C •
h=
r · A2
P20 · 0:H
· tk
.
ln ( 1 + O'.R • ('19k Jim ~ 2~ °C)) 1 + O'.Jl · ('19a 20 C)
(11.49)
In this expression, t;k is the d'il,ration of the short-circ'il,it citrrent, 79a the initial temperature of the conductor when the short circuit occurs and 79k lim is the permissible maximum temperature of the conductor in case of a short circuit. For grooved contact wires of electrolytic copper, values of 125°C to l 75°C are specified as permissible maximum temperatures. Higher temperatures are permitted for contact wires of CuAg0,l and CuMg0,5 alloys. Studies carried out by the UIC have shown that a value of 200°C can be assumed here. The permissible final temperature of bronze catenary wires in the case of a short circuit is given as 300°C [11.30] and that of the dropper wires can be as high as 600°C . The short circuit capability values determined using (11.49) are equivalent to thermal short-circuit currents, i.e. h = Ith· The permissible initial short circuit alternating C'il,Trents however, differ from the thermally equivalent short-circuit currents Ith· According to standard EN 60 865-1 it applies:
1r,
I(;=
Ith /
/(rn + n)
(11.50)
where m - factor describing the heat generated by the DC component and n = factor describing the heat generated by the AC component. DIN EN 60 865-1 gives factors rn and n as functions of the duration tk of the short circuit situation and of the product of the short-circuit duration and frequency, tk · f. In the DB network, realistic values to be expected are m - 0,1 and n = 0,95 m in the centrally supplied parts and m ~ O,G and n ~ 0,95 in the decent.rally supplied parts. The values given apply to short-circuit durations between 0,04 s and a maximum of 0,06 s. This gives the following results: in the centrally supplied network and I(;~ 1 · I1.1i in the decent.rally supplied network. I(; ~ 0,8 · 11.11 Figure 11.21 shows the short-circuit current-carrying capacity as a function of the circuit-breaking time of a contact line frequently composed of a contact wire Cu AC-100 and a catenary wire BzII [>0. Further data and explanations concerning the short circuit capability of contact. wires, catrnary wirrs and droppers are given in [11.3].
I
i II I'
i
I !
11 Current-carrying capacity and protective provisions
592
60
0
120 180 240 ms 300 Duration t k _ ____,__
Figure 11.21: Short circuit current-carrying capability of a contact line, 10 % worn contact wire type Cu AC-100, 50 mm 2 catenary wire type Bzll, 19a = 70°C; 79Klim = 200°C, = 300°C and = 600°C for contact wire, catenary wire and dropper wire, respectively. 1: contact wire short circuit at a dropper at mid span 2: catenary wire short circuit 0,5 m away from a dropper at mid span 3: catenary wire short circuit at the dropper at mid span
20+---+---~---------~ I
1:--~--\~----~----i Measureme ts
1
'
'..._ _JQ.HL (t) id ? : . l m a x t - - - = - - - - - - - ~ - -
1 (t) 0 '-------.e---------1---------+--
o
150 Duration
300
ms
450
t ---
Figure 11.22: Measured fusing currents, stationary vehicle, contact wire type Cu AC-100, simple carbon contact strip. o Measurement made by DR, Recommended limit values
11.1.3.8
Figure 11.23: Rating based on continuous current-carrying capacity. - Load current on contact line section I(t) - - Continuous current-carrying capacity of contact line IoHdt)
Fusing current
For practical applications, the fusing current causing the contact wire to melt is relevant. This current depends on the current duration tsc to a high extent. Figure 11.22 shows currents measured in Germany necessary to melt a contact wire Cu AC-100 depending on the duration of the current in combination with one carbon collector strip. The continuous contact current for the combination can be assumed as 100 A. From the measurement recommended for the permissible contact stress as a function of the duration period can be given by Icon perm -
1200/tsc
100 in A,
(11.51)
where tsc is the duration of current action. For Cu AC-120 contact wires the permissible values are higher by 20 %. This function is depicted in Figure 11.22 as well.
593
I
a)
b)
\
\
\
' ' ....
I \
1rn11 (t)
<
c) I
\
\
I max
l
\
I max
\
\
IOIIL(t)
<
I max
\
\
10HL(t)
\
< \
\
""
:\
' ' ......
c !§ Q)
0
Duration of load
Duration of load - - -
Duration of load - - -
Figure 11.24: Design calculation principle: matching load characteristic (-) and currentcarrying capacity characteristic (- -) . a) Operating equipment rating too generous b) Optimum operating equipment rating c) Operating equipment rating inadequate
11.1.4
Thermal design calculations
11.1.4.1
Maximum principle
Electric railway contact lines should be designed in such a way that damaging overloads are avoided even when the maximum expected load occurs. However, it is also desirable to achieve a well-balanced average utilisation of the contact lines. These contradicting requirements can be met satisfactorily by applying methods that take into account the real characteristics of loads and system capabilities. In the rnaxirnurn principle, which is still often used, the continuous current-carrying capacitv Ic1 is taken as the basis of all calculations. In this case, the criterion assumed is that this value must be equal to or higher than the ma:cimum expected load current Irnax (Figure 11.23) at all times. In such a case, the contact line never reaches the permissible maximum temperature during normal operation, because the peak loads only occur during short periods. For this reason, this method is uneconomical and not to be recommended if the timedependent loads are known.
11.1.4.2
Matching load and current-carrying capacity characteristics
Fig me 11.24 illustrates the principle of this thermal rating design method. The graph of the time-weighted load cmreut I(t), representing the load, is matched with the graph of the Liwnnal characteristics IoHr,(t;) of the 01wrating equipment, i.e. the traction contact line. Tlte ol>jcc-tive is to achieve the best possible match of the graphs of IoHL(t) and !(/) as sl1owu in Figun~ 112Ll b . 'The thern1cdly determined curre11L-canyiug capacity of
f
____________________ 11 Curreut-carry~!1g capacity and protective provisions
::::::_.:::__ 594
~
5000
'
A
\ 1
''
1:::: -2000
'
''
'v '
2
x[OHL(t)
- Load !(/) '
C
Q)
c31000
'' ~, ,_
'
- ,. __
-- --
- -- --- -
-
-
0
3
6
10
20
60 100
200
600 1000
3600 s 10000
Duration of load - - - - -
Figure 11.25: Comparison of a normally distributed load with a maximum annual hourly mean of 610 A with the current-carrying capacity of a contact line system of type Re 200; contact wire 10 % worn, wind speed 1 m/s, ambient temperature 35°C. 1: contact line system without parallel feeder line 2: contact line system with an Al 240 mm 2 parallel feeder line
overhead contact lines can be calculated using equation (11.23) where Iom,(t) = It. As with Figure 11.11, this principle is also applicable to short-circuit design considerations. Railway lines for general traffic The load current in a feed section of a general traffic railway line can be expressed as a stochastic value according to (11.8) and a mean value as calculated with the aid of equation (11.11). The hourly mean value of the hour in which the maximum load occurs is the maximum load occurring in a main railway line section within an entire year, or, in the case of tramways, the section load occurring due to detour traffic or traffic disturbances. The load current is then expressed as: J ( t)
= h max ( 1
F (Add))
(11.52)
The principle to be applied in order to achieve optimum contact line dimensions can be expressed as: Ior-rdt) - I(t)
--r Minimum
(11.53)
Example: For the hourly mean value of 610 A calculated in 11.1.2, the dimensions of the contact line system should be determined to satisfy tlw therrual requirements. Figure 11.25 shows graphs of the load J(t) and of the load-h0aring capacity lorn (t) as functions of time. As seen loads with long duration will exu,ed the load-bearing capacity of a contact line without parallel feeder line. However, if Llw real wind speed vw 2': 1,8 m/s is taken into account, normally occurring when ilai, = :3f>°C as described in clause 2.3.1, the contact line without a parallel feefkr will still achieve th
595
2500 \
\
A
\
\
'
2000 · headwa 7 min
'
- - _ Be 330 with FL
1500 ·
-----
headway 15 min 1000 ·
c
~
'5 500 ·
u
0 10 100 Averaging period /*
1000
10000
s
100000
Figure 11.26: Compa.risou of the reference resistance Iom,(t*) of a contact line Re 330, with and without parallel feeder line (FL), to the load J(t*) on line branches used by high-speed trains, as determined in clause 11.1.3.
High-speed railway lines For high-speed railways, the rating must be based on the time-weighted parameters (cf. clause 11.1.3) ; the principle to be applied being:
I or-rd t*) -
Ieff max ( t*)
--+ Minimum
(11.54)
Figure 11.26 shows the time-weighted current-carrying capacity of an overhead contact line of type Re 330 in comparison to the load of high-speed trains as calculated in clause 11.1.3.
Example:
It is possible to draw conclusions about the real thermal behaviour of overhead contact line installations by comparing the time-weighted load to the time weighted current,carrying capacity of the contact. line. Assuming the load situation discussed in detail in clause 11.1.1.3, we obtain the relationship shown in Figure 11.27 for a contact line of type Re 330. In this case the ambient temperature in the tunnel was assumed to be '!9air = 30°C and the wind speed was _;:tssumed to be vw = 0 m/s. The contact lines of the two tracks under consideration are connected together at a distance of 10 km from the feed point and at 5 km intervals thereafter.
.
11.2
Effect of the temperature on contact wire characteristics
11.2.1
Introduction
Clause 11.1 descri hes tit<~ basis for the detennination of current eapaci ty and t/u;rrrwl rn.tzng of contact hrws. This section deals with the basis for limit tcm1wntt11res and presents the conscqucHc<'S of contact wire~ oprration at elevated tcmpcrat.111rs, which may occur from increased power cous11mption, after short circuits and iu casr of failures of protective dcvic<\S or circ11it lnraJ..c\rs. Local t.emperatun) rise rnav lw caused for <'xa111ple !iv d,1mag<'d co1111<'c!or fi!tings or cavit.i<\S in t!tC' contact \\ir<' 1
i:i
I.
11 Current-carrying capacity and protective provisions
80 ~--~------.----,-------,-----,----------,
oc
70+----l------+---+----1--------J-~---·k-·I
Figure 11.27: Rating of an overhead contact line for use by high-speed trains in a tunE nel, without parallel feeder ~ 10-J
:5 30 § ~ 20 -l"-+-"-"'--"--1-P-----l~"s:-+--l-"~f"...::.+---f-"'----f+-'~f---'ql'---~-,
'
Apart from this, highly localised and short-term temperature rise may occur where the collector strips touch the contact wire, and the melting temperat1LTe of the contact wire material may even be exceeded. The associated reduction of the tensile strength of the contact wire and the high collector strip wear limit the capacity of DC railway traction power supply systems. Currently, the maximum economically and technically manageable current allowed to flow through a contact wire-collector strip junction is deemed to be approximately 2000 A. Increasing contact wire temperatures tend to increase the permanent elongation and to decrease the tensile strength. Additionally, the mechanical properties of the wire change depending on the tensile stress in the contact wire and on the time it has been in operation. Tb,~ wire drawing process and the cross section (sec Table 2.11) also affect the behaviour under temperature changes. The effects of these parameters on the contact wire characteristics will be discussed in this clause. They are essential ·when assessing the residual life of a contact wire in question.
11.2.2
Metallurgical principles
Contact wires are subjected to a near-constant tensile force undc•r normal operating conditions. The mechanical load can lie a,ss11med as heiug static Apart from the mw:im,u·1n, tensile .,trcn_qt.h or no'111:1,1w.l lensi/1'. st.n:.nyth, th<' 0,'..? c;; ywld sh,ength is an
l_!:_2_~ff~ct of the temperature or!_<::2!~:_a__<:_t wire characteristi,<:~"----· ____________:::.:::_:__ 597
600 N/mm2
Rm= 505 N/mm 2
500
400
I
Cf) Cf)
Q)
ti 300 ~
·u; C
Q)
1-
200
100
0
I
I
0
--
I \
\
I 2
3
4
5
6 Strain - - - - -
7 % 8
Figure 11.28: Tensile testing of a contact wire of CuMg0,6 according to EN 10 002, Part 1.
Table 11.10: Physical properties of electrolytic copper at a temperature of 20° C, according to reference [11. 31]. Property Density Specific heat Melting point Linear expansion coefficient Cubic expansion coefficient Thermal conductivity Young's modulus (modulus of elasticity) Electric conductivity Temperature coefficient of electric resistivity Tensile strength, hard-draw E-Cu
Value 8,9 385 1083 16,5 ·10- 6 17,7·10- 6 391 127 58 (68 to 70) · 10- 5 300 to 360
Unit kg/clm 3 W s/(kg · K)
oc
K-1 K-1 W/(K·m) kN I mm-·) S · rn I mm-·) n · rnm 2 /(rn · K) NI mm-·)
important parameter describing the strength of components subject to static loads. In ductile materials, major permanent elongation occurs if this limit is exceeded. Copper contact wires, made of relatively hard materials, show no clearly defined elastic limit. The 0,2 % yield strength is the tensile stress which will cause a permanent elcngation or set of 0,2 % after the load has been removed. Figure 11.28 shows the stress-strain diagram obtained in a tensile test of a contact wire made of CuMg0,6. The diagram shows the wide range of stresses over which the strain is directly proportional to the stress. Until approximately ten years ago, contact wires were made of electrolytic copper usually because, in a pure condition, it achieves good mechanical strength while having a. low resistivity. Table 11.10 lists physical properties of electrolytic copper as given in [1 L:31]. However, modified overhead contact line properties are required in order to a.chic~\ e high running speeds at the same time assuring the required level of current !.ra11sl"C'r and c-ontac:t. quality.
598
- - - }!_ Cunent-cai:i:ti11g,_ capacity and protective provisions
As explained in chapter 9, t.lw contact characteristics of a pantograph an
11.2.3
Effect of heating on the tensile strength
Long-term heating of cold-drawn copper wire causes the crystalline micro-structure to regain the original structure it had before the cold-drawing process. This transition to the stable crystalline micro-structure is called recry0tallizatwn and is accompanied by a loss of all physical characteristics typical of tl1c cold-drawn contact wire. Figure 11.29 shows how the tensile strength of cont.ad, wires made of Cu. CuAg0,l, Cu.tVIg0,4 and Curdg0,6 decreases due to recrystallisation. As the recrystallisation temperature is exceeded, the micro-strncture begins to change acc0111pa11iec! by a loss of tensile strength. In this process, the crystalli1w grain n~-assnrnes the stable round shape and the micro-structure created by cold dra.wiug is al1t1ost totally corncrted. The reduction in tensile strength ca.11 lw evaluatt'd 011 tlw basis of the annealing point. This is the U\mp<\ratmc at \Vhich th<' material n11t IH~ k('pt for orw hour until its tensile
!_1.2 Effect of the temperature ou cm1~~~~:t_~ire characteristics
------------
550
t
--"- ~"'I
N/mrrf 450
-
400 Ol C fl:' 350
-"
U)
.!le'
300
Q)
250
·enC I-
I I
,_
.c
yCuMg0,6
------
"'
"I>:::-- I=::::=-
CuAg0,1~
cu./\
'\ -CuMg0.4
-
l
200 20
100
150
200
250
300
350
'100
°C
B ---------500 N/mm
2
------------
r---
400
1 .c
Ol C fl:'
U)
.!le' ·en C
300
annealling point at (500+270)/2 = 385N/mm 2 corresponding temperature 380°C heat application time 1,5 17
Q)
599
500
Figure 11.29: Tensile streng,th of various contact wire alloys at rising temperatures.
I\ i\
~
--
I-
200 200
350 300 400 450 C0 500 250 Annealing temperature - - -
Figure 11.30: Determination of the annealling point of CuMg0,6.
strength drops by half the difference between the original high tensile strength and the final, low tensile strength that the material takes on, after being kept at high temperature for long periods. How the tensile strength drops is a function of both the temperature and the period of time the material is kept at that temperature. For example, for a material conversion ratio of 60 % and an exposure of one hour, the annealling point is 215°C for copper wires and 340°C for contact wires of CuAg0,1. By comparison, if the conversion ratio is 85 %, the corresponding values drop to 180°C and 300°C respectively. Figure 11.30 shows a graph for determining the annealling point of CuMg0,6 with a conversion ratio of 85 %. The loss of tensile strength of copper wires due to heating increases with the duration of time that the material is kept at high tempePttures, with the conversion factor and with purity of the copper. Alloying copper with silver delays the tensile strength reduction dramatically [11.32]. In [11.33] the effect of heating on the loss of the tensile strength of copper was studied when subject to periodic temperature changes and when kept at constant ternperatures in the 100°C to 150°C range . It was discovered that a series of short-tcrn1 exposures to higher temperatures did not affect the tensile strength. In studies carri<~d out on the same subject matt.er, was drawn the same conclusion [11.34]. A set of equations descrihiug the relationship between temperature, minimum tensile strength and 0,2 % .,,idd st.r<)11gth has beeu developed through rn1111H<~hcusive ex-
______ 11 Current-carrying capacity and protective provisions
600
b)
r~ ~
a)
~
X ro_
-
~+-=:=l=----"l
II
I
II:
er: :
A= 12,81
Figure 11.31: Contact wire Cu AC-100. a) cross-sectional profile -- b) local reduction of cross-sectional area
perimental work and theoretical considerations [11.35]. For E-Cu contact wires, the following numerical equation can be used to determine the minimum tensile strength:
a-= 318 - 0,345 · {)
(5
19
N/mm 2
°C
and, using the same units, the equation for the 0,2 % yield strength is: a- 0 .2
=
160,5 · exp [154,7 /(rJ
+ 273)]
[11.36] contains data on the effect of contact wire temperatures on minimum tensile strength and 0,2 % yield strength. They were obtained from tests on contact wires Cu AC-100, the profile of which is plotted in Figure 11.31. The measured data validate the above equations.
11.2.4
Effect of exposure to increased heat on tensile strength
This section describes the conclusions drnwn from experimental measurements to determine the relationship between minimum tensile strength, 0.2 % yield strength and period of exposure to increased temperatures. In [11.37] copper with a conversion ratio of 58 % was analysed. The tensile strength of wires being initially 370 N/mm 2 was reduced by 10 N/mm 2 after the wire had been kept at 120°C for a year, and by 30 N/mm 2 if the wire had been kept at 160°C for a year. It was found that the tensile strength of copper contact wires of tvpe Cu AC-100 kept under a constant stress of 150 N/rrnn 2 started diminishing at a temperature of 120°C. The reduction in tensile strength starts earlier for higher constant operating tensile stress. In [11.38] new and used contact wires of type CuAg AC-120 and C11 AC-120, were investigated under mechanical loads and without loading, to stuclv Lhe effects of the operating tensile force, operating temperature and duration of load application on the
11.2 Effect of the temperature on cont.act wire characteristics_
-------- _ --- ----------------- 601
0,6
%0
5.-----~-----.-------,
+
0,5
100 N/mm 2 0,4
i - - - - - t - - - - - - : - i- 4
I
C
0
';ij 0,3 0)
C
---r---;--
0
ai Q
~ 0,2
u
fr
150 N/rnrn" 0,1 0
150 N/mm2
5 6
7
0 500 1000 Period of exposure - - - -
h
1500
Figure 11.32: Ageing behaviour of contact wires of type Cu AC-120 and CuAg AC-120; change in tensile strength, expressed as a percentage: unbroken line: Cu AC-120 at fJ = 120°C; measured values o: CuAg AC-120 at fJ = 170°C; measured value +: CuAg AC-120 after wetting by rain; The values shown represent the operating tensile stress in N/mm 2 .
0
200
400
600
1----
800
h 1000
Figure 11.33: Time/elongation graphs of contact wires of type Cu AC-120. CuAg AC-120 and CuMg AC-120: 1: Cu AC-120;
= 120°C; as = 150 N/mm 2 i9
2: CuAg AC-120; i9
= 170°C;
150 N/mm 2 3: Cu AC-120; i9 = 120°C; as = 100 N /mm 2 4: CuAg AC-120; i9 = 170°C; as 100 N/mm 2 5: Cu AC-120; v = 120°C; as= 50 N/mm 2 6: CuAg AC-120; iJ 170°C; as= 50 N/mm 2 7: Cur.lg AC-120: iJ = 150°C; as = 225 N/mm 2
as
tensile strength and the yield strength. The main conclusions of these measurements, the results of which are shown in Figure 11.32, are:
If loads are applied for long periods, the tensile stress has a marked effect on the reduction of the minimum tensile strength and the yield strength limit of contact wires made of copper and of CuAgO,l. Repeated exposure to rain increases the tensile strength of CuAg0,1 contact wires. In [11.39] this is attributed to a rccr:vstallisation effect followed by h,udening under load. After being subjected to an operating stn'ss of 100 :'J /nun 1 over periods up to 1600 hat a constant contact wire temperatm(' of 120°C. the cont.ad wit('S sho-w a tensile strength which do<'S not diff<'r from tlw strcngt Ii of the 1111loaded material
_! 1 Current-carrying ~<:1:pactty and protective provisions Table 11.11: Effect of temperature and period of time of exposure to raised temperature on the tensile strength of contact wires of type Cu 100 subjected to an operating stress of 100 N /mm 2 in accordance with measurements described in (11.35).
Tcmperatur
Duration
'!?
t h
120
100 200 300 400 100 200 300 400 100 200 300 400
oc
140
160
Reduction in tensile strength % -0,83 -1,09 -1,22 -1,36 -1,5 -2,2 -2,9 -3,3 -2,2 -3,0 -3,5 -4,0
by more than three times the standard deviation of short-term tensile strength measurements carried out at room temperature. The respective standard deviation for electrolytic copper contact wires was found to be approximately 5 N/ mm 2 . Only after the operating stress is increased to more than 125 N /mm 2 and 1500 h operation at 120°C does the tensile strength decrease by more than three times the standard deviation of the original tensile strength measurements. The permanent elongation of a contact vvire of type Cu AC-120 subjected to an operating stress of 100 N/mm 2 and a temperature of 120°C was found to be over 0,05 % after 600 h at the raised temperature, the elongation increasing slowly with time (see Figure 11.33). A contact wire of type CuAg AC-120 with an operating stress of 100 N/mm2 reaches the 0,02 % limit of of creep after being su bjectecl to a constant temperature of 175°C for 400 to 500 h. If the wire is exposed to rain several times during this period, the creep increases to 0,035 %. (Figure 11.32). [11.35] also discusses how the time that a wire is kept at higher temperatures affects its tensile strength. Table 1l. 11 lists the results of this study. [11.40] describes tests carried out on samples of contact wires with a length of 0,7 m which were subjected to internal heating by cmrent loading and to external heating for various periods. During these tests, provisions were made to ensure that the temperature difference along the length of the sample remained below five degrees. Table 11.12 shows the results of these measurements. The hypothesis of a standard distribution of tensile strength values was also confinncd by these measurements. Apparently, long-term internal heating clue to current loading leads to a more rapid decrease in the tensile strength than heating by external sources.
11.2 Effect of the temperature
011
coutact. wire characteristirn
603
Table 11.12: Experimentally determined values of the tensile strength of contact wires of type Cu AC-100 and their standard deviation for different heat heating conditions [11.35]. 0,2 % Tensile strength Current Heat exposure Tem1ierature time A
oc
Irllll
Mean values NI mm-.,
Standard deviation N/nun 2
proof limit
289 270 282 240 299 283 286 282
1,0 5,7 3,3 5,8 2,9 11,4 6,3 4,9
240 235 235 225 250 2:10 248 235
100 140
1
1500
100 140 100 140 100 140
30 1 0 30
160
oc
l
140 120
~100
co
al ~80 2 Q)
~ 60 0
I
co
c
8
I
40
/
20 50
100
150
Duration of heating I _ ____,,_
11.2.5
200
s
250
N/mm 2
Figure 11.34: Temperature of the section of c01itact wire experiencing the greatest temperature increase depending on the heating duration [11.36]. 1: contact wire Cu AC-100 2: contact wire Cu AC-100, evenly worn by 35 % 3: at large distances from position of locafo,ed wear 4: localised wear 25 %, l = 0,1111 5: localised wear 25 %, l 0,2 111 6: localised wear 35 %, l = 0,1 m 7: localised wear 35 %, l = 0,2 m 8: localised wear 35 %, l = 0,4 m
Heating and reduction of contact wire tensile strength at locations subject to increased wear and at connection terminals
Figure 11.31 shows schematic-illy a contact wire that has been worn unevenly. The temperature distribution along this section of contact wire was calrulatecl using methods which accurately model the variable heating characteristics. Th<' results of the calculations are shown in Figme 11.34. This diagram shows the temperature of the section of a contact wir<' of type Cu AC-100 at which a current of 1000 _.:\ leads to the strongest heating effect depending on the duration of heating. Cross section reductions of 25 % and 35 %, an arnbi<'ut temperature of 35°C and a wind speed of 1 m/s were assumed in the calculations . Th(' results show that for localised contact wire wear of sections of 0,4 1t1 length or loug()r, the condition of the contact wire should only be assessed on the basis of the n·rnailling noss-scctiomd
60--1 -·--- ~ - - - - - - · - - - - - - -
.. - _ ..11 Cunent-ca!rfi~g._capacity and protective provisions .
area of the excessively worn section. If the heat which is conducted into and away from a volume element of a wire as the result of the changing cross section is included when setting up the equation (11.16), the power transmitted along th<\ wire due to thermal conduction can be described by the equations: (11.55)
dPout
8
= A Az:+d:i: u.T 19(:r + d:r) ,::i
(11.56)
If both the heat conduction along the contact wire and the fact that (8rJ)/(8t) = 0 for stationary conditions are taken into consideration in (11.16), the resulting differential equation describes the temperatures along the axis of the conductor [11.14]. The solution of this equation for a contact wire is:
,a( ) -_ (·a'UK
'U X
-
9
1 end
) e -1:tl/B
+ ,.oVend
(11.57)
In (11.56), {JK = {) (0) is the increased temperature occurring at a position where the cross-sectional area is reduced locally or where a faulty fitting is placed and {)end= 19(x-+ ±oo) is the temperature at points a long distance away from the section with reduced cross section. The localised thermal constant B in equation (11.57) is calculated by:
B = J>-A/(a U)
(11.58)
This parameter B having the unit of a length can be used to estimate the length affected by changes in cross-sectional areas or by localised additional heat sources. It can be assumed that conductor temperature is increased on a length of ±3 B, in total 6 B.
Examples:
From Table 2.11 the following values are read for a contact wire of type Cu AC-100 with ,\ = 377 W /(K·m): U = 0,0412 m, A = 10- 4 m 2 , o: = 36 W /(K- 1112 ) at vw = 1 m/s. Inserting these in (11.35) gives a value of B = 0,16 m. This means that the transitional state has virtually decayed at a distance of 3 B = 0,5 m. For a grooved contact wire type CuMg AC-120 made of CuMg0,5 under the same wind speed conditions and U 0,0454 m and>.= 59 W /(K·m), it is obtained B = 0,07 m.
These examples confirm that, in cases of localised reductions of the cross-sectional area, only the remaining, reduced cross-sectional area may be used to assess the thermal capability of the Cu AC-100 contact wire if the worn section is 0,4 to 0,5 m long or longer; for Cul\Ig AC-120 contact wires, this length is 0,2 m. Using this information, the effect of increased contact wire wear can be assessed e.g. at concentrated lllasses, ripples or kinks (see chapter 14) The reference [11 19] describes measurements a.ncl calculations of the localised temperature distribution ;:,,long a new contact wire of type Cu AC-100 which had a 40 mm long section in which the red11c<~d cross-sectional area, wa.s 50 % of the nominal c:ross section. Figme 1L3.S shows llw n's1tlts of the im<'stiµJ1Liou that indica.te c11n<'nts in the region °
605
t~
- ~---~' -
2l 40
~
/
(1l Q)
8 30
------
Q)
=i ~ 20 Q)
I= 500A, t = 15min
...___ I
1000A, t
= 60s
Q_
E
~
ro 0
10
0
_J
m
0,2 0 0,2 Distance x - - - - -
1,0
1,0
Figure 11.35: Localised l.
Table 11.13: Heating time constants, in minutes, and heat transmission coefficients, in W /(K-m 2 ), measured on overhead contact fittings and connectors [11.19]. T
vw Contact wire connector Contact wire feed fitting Cross-type current fitting Compression clamp 50/95 Compression clamp 35/35 Parallel groove clamp 1) for vw
= 0,9
= 0 m/s 24,5 23,4 33,9 20,8 11,3 35,2
0:
vw
= 0,8 m/s 11,7 8,2 1 i 11,7 1 ) 6,3 3,9 15,7
Vvv
= 0,8 rn/s 28,5 33,6 29,0 21,4 39,0 24,4
m/s
of the continuous current-carrying capacity only lead to a slight over-temperature at the position of the reduced cross section even if they flow for longer periods. Conversely, a current of twice the value of the continuous current-carrying capacity leads to a local temperature rise of almost 15 K in 60 seconds. A comprehensive series of measurements described in [11.19] and [11.40] confirms that the temperature of contact wires of type Cu AC-100 in the vicinity of a connector fitting only differs slightly from the fitting temperature. Table 11.13 shmvs the values of measured heating and cooling time constants and heat transmission coefficients of overhead contact fittings and connectors.
11.2.6
The tensile strength of contact wires at the contact wire collector strip interface
A considerable proportion of all damage to overhead contact line installations is caused by short-term therm.al e_[f'r.ct;s due t.o arcing between the contact "ire and the collector st.rip due to poor electric contact between the two. The process whir·h leads to the destruct.ion of the contact wire is associated Yvit h a localised recrystallization of the copper and the formation of pits and dents. There a.re several physical processes occurring at the point. of cont.ad, bct.w<\Cll tit<' collector-strip and the contact wire which contrillltt (' to contact wire fail me:
- - - -____________J 1 Current-carrying capacity
606
and protective provisions
2500
2000
1500
Q)
~
1000
m 0.-
E 2 Q) ()
{!
::J
500 1 - - 1 - - - - - - - - + - - - - + - - - - - - - - + - - - - - - - - - <
Cf)
0 0, 1 0,2 0,3 Duration of circuit action
0,4
s
0,5
Figure 11.36: Temperature of the contact surface of a carbon collector strip at the contact point as a function of current action period, as determined by different methods, (see [11.40]), current 1000 A. Carbon strip properties: ry = 1810 kgm- 3 c 140 Wskg- 1 K- 1 .\ = 30 W /(K-m) Po = 30 · 10- 5 nm
the current distribution in the contact wire and the collector strip at the point of contact, the heat distribution in these areas, the mechanical stress of the contact wire, any plastic deformation occurring in the contact wire at the point of contact and the magnetic field. Several theories have been formulated to describe the simultaneous processes. Usually, models based on contact areas or single-point contacts are used. Figure 11.36 shows the temperat1tre increase of the contact sur:face of a carbon collector strip at the contact point as a function of time. In the case of a short-circuit on the traction vehicle, the temperature distribution equation due to the interaction of the contact wire with the collector strip does not enable a direct estimate to be made on the period of time it would take to destroy the contact wire. The contact wire heating model will have to be complemented by a model of the contact wire deformation and destruction process. A model extended in this way was used in (11.40] to establish relationships between the tensile strength of a Cu AC-100 contact wire and temperature by section-wise linear curves as shown in Figure 11.37. This model also accounts for the processes occurring in the copper when short-term heating takes place. Thr. copper material begins to recrystallise even if temperatures of 400 to 500°C occur for less than one second. In practice, such conditions may oecur at vehicles at stand still or moving slowly drawing high currents or \Vhere contcict strips are worn and damaged.
607
380 N
[ii
mm 2
lij
340
!I
320 300 280 260 240 220 I!! 200
_!
180
()
~ 160 0
()
0 140 .c
oi 120 C
Cl)
t7J 100 80 60 40 20 0
100
200
300
400
Contact wire temperature - - - - - ·
11.2.7
500 °C
600
Figure 11.37: Section-wise linear approximation of the relationship between the tensile strength of a type Cu AC-100 contact wire and its temperature. 1 new contact wire 2 contact wire after long service and exposed to heat for at least several minutes 3 new contact wire; heated by current impulses with a duration of less than several seconds
Conclusions
The preceding discussion of the thermal characteristics of contact wires enables the following conclusions to be made: No sudden change of tensile strength and elastic limit occurs if contact wires under operating stresses between 100 and 130 N/mm 2 are heated to 120°C to 140°C. The main mechanisms that may lead to contact wire damage in this operating range occur at locations subject to excessive wear, thermal disturbances in currentcollecting components and faulty connectors that may cause plastic deformation and low-temperature material creepage. Micro-structure changes start to develop in electrolytic copper contact wires at temperatures of 100°C to 140°C and stresses exceeding 130 N/mm 2 . However exposure to such conditions for as long as 30 minutes does not cause any noticeable micro-structure changes. Extreme micro-structure changes of a contact wire may occur where cunents pass into and out of the wire. Here, recrystallisation zones in the rnntact wirr reduce its tensile strength. T<'tuperatures of 120°C t0 140°C may lead to au acc11t111dation of plastic deformation and reduce the tensile strength tu bdow 27:1 N /mm2 and the 0,2 % yield strength to 230 N/mm 2 . An additional mechauism in cumulative damage to contact wires is plastic deformation d1w to stn~sscs e:-..ceccling the dasric: limit ot·nmiuµ, at lontt,ions ,, here
608
11 Current-carrying capacity and protective provisions
faulty connection components are installed and where the temperatures exceed 180°G The heat proo.fness of contact wires is improved markedly by addition of approximately 0,1 % silver to the alloy, which also reduces the creepage. Recrystallisation of these alloys commences at higher temperatures than for electrolytic copper. The electrical properties are the same for both materials. Magnesium-copper--alloy contact wires containing approximately 0,5 % magnesium have favourable thermal and mechanical properties which permit the use of high tensile forces. The less favourable electrical properties of contact wires made of these materials can be compensated by using catenary wires with a greater cross-sectional area or by installing parallel feeder lines parallel to the contact line. For maintaining the permissible contact wire temperatures, the contact line protection is of significance as described in the following section.
11. 3
Contact line protection and fault location
11.3.1
Purpose of protective provisions for contact lines
A suitably designed protective provisions for contact line installations enables the thermal characteristics of contact lines to be fully utilised. This, in turn, is a prerequisite for optimum operation of adequately designed contact line systems. Contact line installations are the components which have the lowest thermal loadbearing capacity in railway traction energy supply systems. For this reason, it is safe to assume that if the contact lines are well protected, all other operating components connected in series with the contact lines will be adequately protected. Protective provisions for contact lines have the basic purpose of sensing and evaluating the occurrence of any faults, in order to eliminate or minimize the hazards to persons being directly or indirectly exposed to or coming into contact with fault currents and voltages, to prevent or keep to a minimum any damage to the contact line installations and equipment, maintain the best possible availability of the traction power supply and provide and process information which assists fault analysis. To achieve these aims, the protective provisions must be able to switch off all disallowed traction contact line loads safely, quickly and selectively. Examples of such disallowed traction contact line loads are: all types of short circuits occurring in the network, operating currents vvhich cause the permissible final temperature '8lim of the contact line to h<~ protected (e.g. 70°C for standard DB contact line designs Re 200 and Re 250 and 80°C for Re 330) to he exceeded. In traction power Sllpply installations, faults occm more freq1wntl)' than is the case in puhli(' pm\'<'r sllppl\· µ,rids
!_1_.3 _Contact line protection and faul~~:,:1.tion_
energy flow
operating equipment
to be monit<2_red
-
(contacl line inslallalion
u
1
609
information on corrective measures lo be taken
s
program auxiliary power
proteclive equipmenl
8 air ___ information for fault analysis
Figure 11.38: Tasks and objectives of protective provisions for traction contact lines.
30001---~--~--~--~~-~--~ A
t 2000
I ~
:5
0
current-carrying capacity of an overhead contact line installation
>
1----1-----4-/ ;
Z<
c)
1000 1 - - - - - 1 - - - - - ' F = = = i a)
a)
0 l-----+-------~--+-----4-+---+----,0,001 0,1 0,01 10 100 s 1000 Duration of current - - - - -
a) Real protection range when protected by EFSl with a power circuit-breaker break time of 60 ms b) Extended protection by thermal protective provisions 12 · t c) Range which can be covered by 1 2 · t and starting-current limitation circuitry
Figure 11.39: Current-carrying capacity of and protective provisions for overhead contact lines.
The tasks, objectives and principle of operation of contact line protection prov1s10ns are provided in Figure 11.38. Figure 11.39 shows the capacity characteristic of an overhead contact line installation together with the protection characteristics achieved by protective provisions using various protective mechanisms. Clause 10.5 describes how power is supplied independently to each feed section via a circuit-breaker. Each circuit-breaker has associated protection circuits and equipment. The lines presented determine the limits by exceeding of which the corresponding protection relays trigger opening of the circuit-breaker. The protective equipment directly handling protection is called the primary protection Primary protection equipment must be able to recognise whether a short circuit has occmred in the associated feed section and distinguish this from faults in other sections.
If the protection relay responsible for a feed section or the associated power circuit.breaker failed, the fault current would not be s,vitched off In such cases, the backup protection provzsi,ons must ensure that the cmrent is cut off. It is usual in such arrangements, to distinguish between back-up protection 1, which is meant to cottw rnto effect if protection relays or power circuit-breakers fail, and back-up protection :2, whic-h is nscd as m,astcr JJTolectwn as described in clause 1. 3.3.5.
6=-=1=-=0-----------~---··- ··-·· 11 Current-carrying_capacity and protective provisions
11.3.2
Protective provisions for overhead contact lines used by the DB
The following section contains a brief description of the protective provisions for overhead contact lines of the single-phase AC 16,7 Hz railway network. The principles and protective provisions can also be used for single-phase AC 50 Hz installations. In the early years of electric traction, simple electromechanical relays were used for overhead contact line protection in supply substations, switching posts and coupling posts. From 1975 on, as suitable electronic components became more available, the older equipment was replaced by electronfr analogue protection equipment, e.g. type SDB15, 7SL16, EFSl and EFS2. Protection equipment for individual overhead contact line sections should meet the following conditions to cope with the special requirements of railway applications, with its marked operating current peaks and the extreme short circuit currents of up to 45 kA: fast high-current circuit breaking, over-current time protection, two-stage distance protection, also called impedance protection, with two sets of parameters and with over-current triggering, ability to distinguish between high operating currents and short circuits, thermal overload protection, emergency over-current time protection to provide for failure of the distance protection provisions, and back-up protection. Instrument trans.formers with appropriately protected transformer cores are used to sense the currents and voltages and provide input for the protection circuits, as shown in Figure ll.40. The short-circuit protection equipment used as primary protection must be able to detect short circuits without fault impedance. It must also detect short circuits at the far end of the section to be protected with a fault impe,dance not exceeding the circuit impedance. The command response period of modern protection relays is in the region of 2 ms. The complete period taken to switch off the short-circuit current is the sum of the command response time of the protection relay and the breakperiod of the power circuit-breaker, that is, the sum of the actual switch-off period and the arc-quenching period. The most important stages of overhead traction rontact line protection relay settings are: High-current protection: I>>> Short-circuit currents due to short-drcuits occurring near the substation, are much higher than those due to short-circuits occurring at the end of a feed section or near the mid-point between two substations because the impedance between the feed point and the short-circuit location is much lower. The purpose of high-current protection is to send an "OFF" signal to the corresponding circuit-breakers as soon as a pre-set limit of the current value is exceeded. The principle of selectivity is not always maintained in high-cmTcnt protection circuits a.s the w-ctn~mdv high short-circuit currents must be pr<'V<)ll1.<'d from nwlt,ing t.lH\ <·cmta.ct. ,vin'
1L3 Contact line p~otection andfault locatil>n _____
voltage transformer measurement and longitudinal isolation 2
measurement and longitudinal isolation 1
X
u
4A
D
611
overhead line section current transformers protection core
measuring core
X
ZL
u
ZK
-T1
4A
<{
0
<{
u
(f)
'--.---------+--
u
----+-----------t--t-----..L..-- V
C
0
ti $
e0.
Figure 11.40: Connection of overhead contact line protection to the voltage and current transformer. Two-stage distance protection: Distance protection is required to be able to selectively switch off short circuits in interconnected networks and also in overhead contact line networks. These provisions, also termed impedance protection, are meant to isolate short circuits occurring at greater distances from the supply substation while maintaining the principle of selectivity. This form of protection operates on the principle of under-impedance triggering. If the shortcircuit impedance is found to be lower than a pre-set impedance value, the distance protection is triggered. The German railway, DB, distinguishes between a first distance (or impedance) protection stage and a second distance (or impedance) protection stage.
1st Impedance stage: (Z <) This is used as primary protection for the overhead contact line as far as the next protection section, for example, between the substation and the coupling post. The "OFF" signal is sent to the corresponding circuit-breakers after a command delay period of 30 ms. 2nd Impedance stage: ( Z <, t) This is used as back-up protection for the neighbouring overhead contact line sections. If the protection provisions in a following section fails, an "OFF" signal is given after approximately 400 ms. The principle of operation of high-current and distance protection of traction contact lines can be explained on the basis of a multi-stage protection plan as shown in Figure 11.41. Here, the multi-stage plan is only shown for po\\·er circuit,-hr<~akers (CB) 132, BC2, BC'1 and C4 for the sake of simplicity. A GO km long s(~ctio11 of track hetw<~en
612
11 Current-carrying capacity and protective provisions
30km
b)
t
30km BC4
400 ms 300
Z<, t
82:Z<, t
200
Q)
E
·.;::;
100 82./>> 100
B2.Z<
BC4.Z< I
BC2.Z<
C4:7»1
C4.Z<
200 300 BC2. ms Z<, t 400
C4:Z<, t
Figure 11.41: Principle of operation of overhead contact line protection. a) Tasks and purpose of protection circuits, including back-up protection LSBC2 for power circuit-breaker - b) Principle of multi-stage protection plan for four protection relays. Bl, B2, B3, B4, Cl, C2, C3, C4 circuit breakers in substations Band C, respectively; BCl, BC2, BC3, BC4 circuit breakers in the coupling post
two substations (SS) was chosen in which the coupling post (CP) is exactly mid-way between the substations. All four power circuit-breakers serving the line under consideration are equipped with contact line protection relays. For the symmetrical arrangement shown and assuming contact lines without parallel feed lines, the impedance settings of all relays are: for the first impedance stages Ze = 0,251 r2/km · 30 km = 7,53 n - for the second impedance stages Ze = 0,251 n/km · 60 km = 15,06 n. The triggering current of the high-current protection circuits is assumed at 1,8 kA. If a short circuit occurs on the contact line between circuit breakers B2 and BC2 (Figure 11.41, track 2), then the circuit-breakers are responsible for isolating the short circuit. Since a portion of the short-circuit currents flows to the bus-bar of the coupling post, the direction-sensing elements of these three relays will prevent them being tripped. If the short-circuit current h is lower than 1,8 kA, the high-current protection of circuit-breaker B2 will not be tripped. If h > 1,8 kA, a break signal is applied to circuit-breaker B2 immediately. The first impedance stages of the relays for circuit-breakers B2 and BC2 sense an impedance which is below the trigger impedance setting of 7,53 n and will generate a break signal for the respective circuit-breakers after a delay of approximately 30 ms. However CB B2 may have already been triggered by the signal due to I >>> if the short-circuit current, which is dependent on the location of the short circuit, was high enough. As a result, the contact line above track 2 in Figure 1 L41 will be switched off between the substations SS and CP will be selectively switched off and isolated. The second impedance stages of the relays for circuit-breakers Bl, C3 and C4 all sense an impedance which is lower than the trigger impedance setting of 15 n and the trigger delay tinwrs are started. However, as long as the circuit-breakers B2 and BC2 switch off cm tinw before tlw ti11H'-011t. tlw s<~cond iuqwdaw·e stages of all three relays are
613
reset to the initial status. However, the relays or the circuit-breaker BC2 of the coupling post failed, the relays of circuit-oreakers Bl, C3 and C4 would send an "OFF" signal to the corresponding circuit-breakers after approximately 400 ms delay. Circuit-breaker Bl would have already been tripped after either 1 ms or 30 ms and switched off the power supply to both subsections of the line section between substations B and C. In this case, where the back-up protection 1 is triggered, the selectivity principle is overridden in the interest of safety. Conversely, if the n~lay or the power circuit-breaker B2 in substation B failed, the following back-up protection would come into effect. The circuit-breaker feeding the bus-bar of substation B ( transformer power circuit-breaker) must be switched off by the respective over-current-tirne sensing circuit. The second impedance stages of circuitbreakers BCl of coupling post BC and of AB3 and AB4 of the coupling post AB (not shown in Figure 11.41) would trip the associated circuit-breakers, causing the entire section between the coupling posts AB and BC to be isolated. Once the protection provisions have been tripped, it is necessary to check whether the short circuit of the section served by the tripped circuit-breakers has been eliminated or not before the circuit-breakers are closed again. This is done by connecting the section to be checked to a test bus-bar which feeds the current through a test resistor limiting any existing short-circuit current to 5 A. This procedure is called section testing and can be started either manually or automatically. In the case of automatic section testing, the protection relay associated with the section circuit-breaker initiates the tripping and re-closing of the main circuit-breaker, the required changing of the section isolator and the evaluation of the test results. For more information, refer to clause 1.3.3.5. If it is confirmed that the short circuit has been eliminated, the section is reconnected to the operating power bus-bar. If a permanent short circuit is detected, it will have to be localised and corrected.
Distinction between operating currents and short-circuit currents On lines where the traction vehicles draw very high starting and acceleration currents, a .6,J / .6,t trigger is used to distinguish between starting currents and short-circuit cunents. Once this protection stage senses a short circuit due to its steeper current rise, the second impedance stage is activated. Thermal overload protection TheT'mal overload prntection serves to ensure optimum utilisation of the overhead contact line up to a pre-defined limit temperature 'l?iim· This device measures the operating current flowing through the circuit and thus the heating effect of this on the overhead contact line. Even imprcved utilisation of the overhead contact line installation can lw achieved if the ambient temperatmes ell<) also monitored, so that the overhead line tcrnpern.tun~s can be modelled more exactly by shifting the characteristic curves to 111atch the weatlwr conditions. 111 such svsU\lllS, the ambient ternpernture is measured h,· a L<'ttqwrature sc)ttsor mo1111t<'d 011 a Notth-L,cing rn1tsiclc) wall of the building that
11 Current-carrying capacity and protective provisions
614
rectifier substation or coupling substation
actual and limit value comparison _J
effected in the same way by ambient temperature &air and air flow vw
track
Figure 1L42: Thermal protection with direct measurement of the contact wire ternperature.
houses the switchgear. The temperature information is passed to the protection relay control circuit's algorithm by means of a proportional voltage signal (0 to 10 V). Thermal protection devices in which the contact wire temperature is measured directly have proven to be particularly efficient [11.41]. Figure 11.42 shows a protection device of this kind.
Back-up protection An additional over-current/time protection can be implemented as back-up protection. This is equipped with a power supply which is independent of the main protection power supply and is connected usually to the measuring core of the current transformer. Its trigger excitation current is used to activate the second tripping coil of the circuitbreakeL Such systems achieve a high degree of redundancy. A protection of this kind is only used in special applications, as the modern digital relays are reliable. Overhead line protection systems are equipped with remote-controlled facilities for setting the impedance conditions and the thermal protection limits. It is necessary to nx:onfigure the system to higher impedance values and/ or lower thermal load current Yalues when line sections, normally opr.ri'tted with two tracks, are partly operated as single-track sections to ena.hle construction or repair work
615
Since 1990, digital protection relays have become increasingly used in railway traction systems. In addition to the these functions, such devices enable a comprehensive range of parameter settings, options for storing and evaluating protection data as well as circuit-breaker fa.ilure protection which checks means of auxiliary switch contacts whether the circuit-breaker has really been tripped after receiving the main protection trigger signal by measming the current or by. In case of circuit-breaker failure, the back-up trigger is activated. If this also failed, a signal would be sent to the next higher protection level which will then trip all other feed circuit-breakers in the affected switching substation. Continous monitoring of currents. voltages, impedances and trigger signals combined with the possibility of graphic failure data output, facilitates fault analysis and diagnosis of equipment performance. vVhen short circuits occur, the recorded impedance values allow the fault to be localised. Data dialogues with the digital protection circuitry are effected by means of serial data transmission interfaces and the aid of hand-held data equipment or personal computers. At the same time, it is possible to acquire data remotely from unmanned substations by telemetry. For safety reasons, there is a clear function-oriented and equipment-wise separation of control circuitry and protection circuitry in standard switching substations of the DB. Whenever protection equipment is tripped, an overhead contact line short-circuit test is carried out, irrespective of the reason for the triggering. In the DB network, 93 % of all protection trigger events are not clue to steady-state short circuits but to temporary, passing contacts or contact line overloading by operating currents.
11.3.3
Fault localisation
The location of a sw,tained short circuit must be found as quickly as possible and isolated with the aid of overhead contact line disconnectors. This enables the continuation of electric railway operations on the remaining sections and allows for the elimination of the cause of the fault and enables repairs to be carried out. Accurate and reliable fault localisation is important and to accomplish this, railwa~- operators use a short circv,it tracing systern based on current transformers. In two-track lines, these transformers, which have a transformation ratio of 600/1 or 1200/1. are installed mainly at the cross-coupling disconnectors, i.e. in the circuit connecting two overhead contact line main groups. If a short circuit occurs, a current, considerably stronger than in normal operating conditions, will flow through the current transformers located to one side of the fault location in single-ended feed, or at both sides of the fault location in double-ended feed S('ctions. The short-circuit sensing relays connected to the secondary windings of th<' transformers will register this change and send a signal to the control centre in cl1rnge of that section, via the local control unit and the associated telemetry modul<'. This, in rnnjunc-tion with the information on \\ hich circuit-breakers have been tripped, ('tl,d>lcs a rough determination of the location of the fault between the positions of thl~ ;,1(·ti,ating c-mrent transformers. In single-track lirws with single-Pnded fc(~ds, the fault location will he knO\Yll to lie beyond the last shmt-('irc:1Iit sensing transformers that detected all over-cmrent. In sillgle.-t1,1l'k liiws wit!i do1Il>le-('JHl<'d fo<~ds, the fault ,vill lH' lc,<,ll<'d lie1,,,('{'ll the two
__________________ 11 Current-carrying _ capacity and protective provisions
616 ~:___
transformers that recognised a change in the energy flow direction. However, other procedures will have to be used to determine whether the short-circuit is in one of the secondary groups of railway stations B or C, in one of the main station groups or somewhere along the line. This is done using the pole-mounted discori:nr,ctor.s and testing the overhead contact line using either the automatic short-circuit localisation equipment of the master control centre, or manually step-by-step. More precise localisation systems, such as used by electric power utilities, were tested in a DB converter substation in 1991 but have yet to come into common usage. When such systems are used, it must be considered that because of railway tracks and parallel conductors in the earth, the line impedance is not a uniform linear function of the distance from the feed point and the moving loads. In addition auxiliary equipment that is powered via the overhead contact line, e.g. switch-point heating, supply of workshops etc. would lead to wrong results if impedance measurements alone were used to calculate the fault location. However, the tests have shown that it is possible to localise the faults with an accuracy between 200 m and 300 m. It is also desirable to locate the positions where transient short circuits occur. These usually only interrupt the power supply for the automatic overhead contact line testing cycle time, i.e. less than 10 s, which does not affect train operation adversely. However, it is quite possible that such faults may cause component damage to insulators, wires or cables. Localisation on transient faults can facilitate inspection and preventive measures against subsequent failure of components, particularly at locations where such transient faults occur frequently. To achieve this, the distance to the fault location must be determined as soon as the short circuit occurs, since it is not possible to locate it afterwards as in the case of sustained short circuits. Here, an evaluation of the measurement data collected by the digital protection circuitry, which records the impedances before and during the short circuit until the current is cut off, is an effective tool. Such systems can log the data of more than one fault event. To determine the fault location, the reactance is used and is output as a resistance or a distance value. The system is relatively accurate, achieving a tolerance of ±500 m for a section length of 30 km. If the fast high-current protection is tripped however, it is not technically possible to locate the fault position. Automatic and highly accurate fault localisation, together with appropriate reporting could reduce considerably, downtimes in cases of sustained short circuits as the repair crew would be able to proceed directly to the fault location. Down-times due to repeated transient short circuits would be reducefl by enabling preventive and corrective measures to be carried out immediately .
11.4 References
11.4
-----------------------
..
617
References
11.1 Schmidt, P.: Elektrische Belastung als Zufallsgrofie und thermische Belastbarkeit von Leitungen bei mitteleuropaischen Bahnen (Electric load as a random magnitude and thermal strength of contact lines of Central European railways). In: Elektrische Bahnen 90(1992)6, pp. 204 to 212. 11.2 Hellige, B.: Beitrag zur Untersuchung der Bela.stung von Energieversorgungsanlagen bci StraJ3enbahnen (Investigation of the electrical loading of tramway power supply installations). HfV Dresden, 1971, dissertation thesis 11.3 Schmidt, P.: Energieversorgung elektrischer Bahnen (Power supply of electric railways). Verlag transpress, Berlin, 1988. 11.4 Lingen J. v.; Schmidt, P.: Strombelastbarkeit von Oberleitungen des Hochgeschwindigkeitsverkehrs (Current capacity of overhead contact lines for high-speed traffic). In: Elektrische Bahnen 94(1996) 1/2, pp. 38 to 44. 11.5 Rohlig, S.: Beschreibung und Berechnung der Bahnbelastung von Gleichstrom-Nahverkehrsbahnen (Description and calculation of the electrical load of DC local railways). HfV Dresden, 1992, dissertation thesis. 11.6 Heide, S.: Ein Beitrag zur Berechnung von Kurzschluf3stromen im 15-kV-Fahrleitungsnetz der DR unter besonderer Beachtung ausgewiihlter Probleme des Fahrleitungsschutzes (Contribution to calculation of short-circuit currents in AC 15 kV systems considering electric problems of the contact line protection). HfV Dresden, 1980, dissertation thesis. 11. 7 Lingen J. v.; Schmidt, P.: Methodik einer zuverlassigen und ressourcensparenden Bemessung elektrotechnischer Betriebsmittel des Hochgeschwindigkeitsverkehrs (Procedures for a reliable and economic design of electrotechnical operational equipment for high-speed traffic). In: Wiss. Z. Techn. Univers. Dresden 45(1996)5, pp. 30 to 39. 11.8 Lingen J. v.: Kurzschlussberechnung im Fahrleitungsnetz (Short-circuit calculation for contact line networks). TU Dresden, 1995, dissertation thesis. 11.9 Kontcha, A.: Analyse elektromagnetischer Verhaltnisse in Mehrleiterfahrleitungssystemen bei Einphasenwechselstrombalmen (Analysis of electromagnetic conditions in multi-conductor overhead contact line systems at single phase AC railways). TU Dresden, 1996, dissertation thesis. 11.10 Pundt;, H.: Elektroenergiesysteme, Arbeitsmappe (Electrical power supply systems, mcurnscript). TU Dresden, 1980. 11. 11 Fischer, R..; KieBling, F.: Freileituugen, Planung, Berechnung, Ausfiihrung ( Overhead power lines, planning, analysis and design). 4th edition, Springer-Verlag, Berlin, Heidelberg, New York 1993. 11.12 BoJrnw, H.: Mittclspa.nnungstedmik (Medium voltage technology). Verlag Technik, l3erli11/lvliiuchen, 1992.
________________11 Current-carrying capacity and protective provisions
::::.:::._::::___ 618
1L13 Siemens: Technische Tabellen, GroHen, Formeln, Begriffe (Technical tables, characteristics, formuli, terms). Miinchen/Berlin, 1994. 11.14 Lobl, I-I.: Zur Dauerstrombelastbarkeit und Lebensdauer der Geriite der Elektroenergieiibertragung (Current carrying capacity and life cycle period of equipment for electric power transmission). TU Dresden, 1985, habilitation. 11.15 Lingen J. v.; Schmidt, P.: Wiirmeiibergang und Strombelastbarkeit von Hochgeschwindigkeitsoberleitungen im Tunnel (Heat transfer and current capacity of overhead contact lines in tunnels). In: Elektrische Bahnen 94(1996)4, pp. 110 to 114. 11.16 Webs, A.: Dauerstrombelastbarkeit von nach DIN 48 201 gefertigten Freileitungsseilen aus Kupfer, Aluminium und Aldrey (Current r.arrying capacity of overhead line conductors made from copper, aluminium and aluminium alloy). In: Elektrizitatswirtschaft 62(1963)23, pp. 861 to 872. 11.17 Held, 0.: Fahrdrahterwiirmung beim elektrischen Zugbetrieb (Contact wire heating during electrical train operation). In: Elektrische Balrnen 45(1974)4, pp. 90 to 95. 11.18 Wisloucl1, I,. A.; Woronin, A. W.: Untersuchungen iiber Warmeabgabe von der Oberflache der in Fahrleitungen verwendeten Leitungen (Investigatios on heat dissipation on the surface of conductors used in overhead contact lines). In: Anlagen der elektrischen Zugforderung, Fachbuchverlag, Leipzig, 1954. 11.19 Petrausch, D.: Beitrag zur Anwendung der thermischen Modellierung for die Instandhaltung und Diagnose der Fahrleitungsanlage unter Beriicksichtigung der Temperaturmessung mittels Infrarottechnik (Contribution to the use of thermal modelling for maintenance and diagnostics of overhead contact line installations considering temperature measurements by means of infra-red technology). HN Dresden, 1988, dissertation thesis. 11.20 Bencard, R.: Querschnittsauswahl von Freileitungsseilen hei zufallig variablen Betriebsstromen und Umgebungsbedingungen nach thermischen und okonomischen Kriterien (Selection of cross sections of overhead power line conductors at randomly variable operating currents and ambient conditions using thermal and economic criteria). Ingenieurhochschule Wismar, 1985, dissertation thesis. 11.21 Lehner, G.: Solartechnik (Solar technology). Grafenau, Koln. 1981. 11.22 Gorub, J. C.; Wolf; N. P.: Load capability of ASCR and aluminum conductors based on long-time outdoor temperature rise tests. American Institute of Electrical engineers. 1963, pp. 63 to 812. 11.23 Rohlig, S.; Rothe, IVL; Schmidt, P.; Wesd1/;a, A. Hohere Leistungsfahigkeit der Bahnenergieversorgung bei modernen Stadt- uncl U-I3ahnen (Higher capacity of power energy supply for modern city and underground railways). In: Elektrische Ba.linen 91(1993)11, pp. 359 to 365. 11.24 Friebel, L.: Thermischer Schutz fiir di(! Fahrkitu11g (Thermal protection of overhead contact lines). HfV Dresden, 1990, tlH!sis for diploma.
1 L4 References
11.25 DB. German railway directive Gbr 997
619
Overhead contact lines.
11.26 Rigdon, W. S.; e.a.: Emissivity of Weathered Conductors After Service in Rural and Industrial Environments. In: American Institute of Electrical Engineers. 'frausactions, Part III, Power Apparatus and Systems, Vol 81, 1962. 11.27 Dressler, TIJ.: DR-Forschungsbericht (DR research report) 1991. 11.28 Mier, G.: Herstellung und Anwendung von Aluminium-Stromschi<'nen (Production and use of aluminium conductor rails). In: Schweizer Aluminium Ruudschau 1984, Heft 3. 11.29 Koettnitz, H.; Winlder, G.; WeBnigk, K.: Grundlagen elektrischer Betriebsvorgange in Elektroenergiesystemen (Basics of electrical operational processes in electro energy supply systems). Verlag Gnmdstoffindustrie, Leipzig, 1986. 11.30 Hubner, W.; KieBling, F.; Meyer, H.: Projektierung der Oberleitung fiir eine Industriebahn im rheinischen Braunkohlenrevier (Hambachbahn) (Planning of an overhead line for an industrial railway in a brown lignite mine). In: Elektrische Bahnen 82(1984)11, pp. 359 to 366. 11.31 Hiitte: Des Ingenieurs Taschenbuch, Band I, 28. Auflage. (The engineer's hand book, Volume I, 28th edition). Wilhelm Ernst & Sohn, Berlin. 1955. 11.32 Freudiger, E.; e.a.: Erweichung verschiedener Kupferarten wahrend dreizehn 1/2 Jahren bei 100°C (Softening of various copper types at 100°C over a period of 13,5 years). In: Schweizer Archiv fi.ir angewandte Wissenschaft und Technik 36(1970)9, pp. 357 to 359. 11.33 Roggen, F.: Erweichung von Kupfer bei zyklischer Erwarmung (Softening of copper during cyclic heating). In: Schweizer Archiv fiir angewandte Wissenschaft und Technik 36(1970)9, pp. 360 to 362. 11.34 Flinl, .J. V.: Einfluss der Erwarmung der Leitungen des Fahrleitungsnetzes auf deren Festigkeit (Effect of the conductor heating in the overhead contact line network on its stability). In: Arbeiten des MIIT 104, Moscowa 1959. 11.35 Busche, N. A.; Berent, vV. .Ja.: Porcelan, A. A.: A.lechin, iV. .Ja.: Entfestigung verschieclener Kupfcrlegienmgcn bei Erwarmung (Annealing of various copper alloys during heating). In: Increase of life-cycle period of non-ferrous metals. Verlag Transport, Mosc:owa 1972. 11.36 Tsclwtscliew, A. P.: Ergebuisse der Untersuchungen mechanischer Eigenschaften von Driihtcn und Seilet1 in Fahrleitungeu (russ.) (Result of studies 011 mechanical characteristics of wires and conductors iu overhead contact lines) (russian). In: Improvement of design and analysis of electric: traction installations. Vc-rlag Transport, Moskowa, 1985. 11.37 Porcela.11, A A.: Uher die zuliissige Strombelastung vo11 Falndrii.ht,c11 (On the pennissiblc c-11n<'nL loadillg of contact wires). In: Vestnik ZNIL !'vluscova UJG,\ Vol. 7, pp. 51 to 511
::._6_20=-----------"----------- _"_______ 11 Current-carryingcapacity and protective provisions
11.38 Szepek, B.: Beitrag zur Ermittlung der Belastbarkeit und Zuverlassigkeit elektrotechnischer Betriebsmittel von Industriegleichstrombalrnen ( Contribution to the determination of the capacity and acceptability of electrical equipment for industrial DC railways). HfV Dresden, 1974,
12 Current return circuit and earthing 12.1
Introduction
The traction current which, in conjunction with the voltage applied to the collectors, supplies power to the railway traction vehicle through the contact line. This current must have a return path. As the current path can be considered to constitute a closed loop, the total return current must be equal to the current flowing through the contact line. \i\Therever the return path of traction currents is discussed in the following sections, the term is considered to include all braking currents. The running rails serve as conductors for the return current. The track is laid on the ground and is extremely long in relation to its width. This, coupled with the fact that the resistance between the rails and earth is finite and the rails have a longitudinal resistance, causes a portion of the return current to flow to earth and back to the substation via earth. Near the substation, this current flows back into the running rails and into the substation earthing system. The sum total of the currents flowing through the rails, earth and any metal objects running parallel to the track in the railway track area, such as cable sheaths and pipelines, is equal to the current flowing to the train. Up to several thousand Amperes may flow in the running rails and cause accessible voltage at the running rails and conductive parts of the vehicles during normal operation. This voltage can be dangerous potentially and can be bridged by passengers and staff. Compared with conventional three-phase power transmission and distribution systems, where hazardous voltages at accessible parts can only arise during fault conditions, electrified railways require special provisions to ensure safety of people and protection of installations. In case of short circuits, the situation is the same as for short-time voltage impact in other electric transmission systems. Some common considerations apply to both direct-current and alternating-current traction systems with respect to return conductor arrangements. There are :::i,lso fundamental differences between the two. In DC railways, the coupling between the rails and earth is found to be completely galvanic in nature, whereas in single-phase AC railways, the ·1:11,clucl'l:ue coupling bet.ween all conductors, i . e. between the rails, earth, contact line, reinforcing feeder lines and return conductors, affects the way the return current is distributed among the individual conductive paths. In DC raihvay systems, the current flowing through earth can lead to dangerous stray cuTrcnt corrosum,, so this portion of the return current must be rninimised. The standard which deals with stray currents in DC traction installations EN 50 122-2, specifies that Llw best possible insulation 11111st he installed bd,ween track am! earth. For this
12-yunent return circuit, and earthing
622
reason, the rails cannot be used directly for implementing the protection against electrfr shock as required in standard EN 50122-1, as the rails would have to be virtually at earth potential to achieve this form of protection. Both of these objectives must be given equal consideration when designing return current paths. ·when operating or short-circuit currents flow through the track of electric traction railways, the rails assume electric potentials that arc not negligible, reaching their maximum values at the feed and load points and dropping to near zero in regions outside of the transition region mentioned in Figure 10.4. In both the normal operating state and in case of short-circuits, the potential difference between the rails and earth must not exceed acceptable values as specified in the relevant standards. In alternating current railways, the rail-to-earth potential differences are reduced by bonding other metallic, conducting elements to the rails, eliminating any possibility of potential differences affecting people and ensuring that the entire system can be switched off safely in case of faults. These measures are called traction earthing. To reduce the rail-to-earth potential in or near direct-current railways installation, other measures are required, e.g. installation of parallel return conductors and/or short circuiting devices. As a rule, control and command system installations for railway operations use the tracks as part of their electrical circuits. The tracks have to be designed in such a way that their electrical characteristics are suitable for safe return current conduction and the earthing, while at the same time serving as part of the electric circuits for control and command. In both AC and DC railway traction systems, adverse effects on other technical devices and equipment in the vicinity are caused by inductive, capacitive and galvanic coupling to the traction current circuit when energy is being transmitted from the substation to the trains. Optimizing the design of the return circuit systems can minimize this interference.
12.2
Terms and Definitions
12.2.1
Introduction
In standards and publications related to r.arthing and bonding, terms are used with differing meanings so that some essential definitions and comments are necessary for a common understanding. These are derived from the European Standard Series EN 50122 [12.1, 12.2], which was elaborated for protective provisions related to electrical safety and earthing and the effects of stray currents with railway traction systems.
12.2.2
Earth
The earth from an electrical point of view is defined as the conductzve so'il, whose electric potential at any point is taken co11ve11tio11ally as equal to zero (see EN 50 122-1 [12.1]). Often the terms reference earth, nc11,tnd co:rl:h, sr'pe,·a/,e earth or remote earth are used. Earth in tlu~ context of this defiuit.io11 is frnltld Olltsid<~ th<' area of interference of
12.2 Terms and Definitions
623
electrical installations, where no potential difference can be detected between different points as a result of earth currents. The distance between earthing installations of energy supply facilities and the earth as defined above can be several tens of meters up to one kilometer and depends upon the dimensions of the installations, the soil composition and the magnitude of the earth current. The earth is taken as reference for determining the rail potential (i.e. rail-to-earth potential).
12.2.3
Earth electrode
Earth electrodes are one or more conductive parts in intimate contact with soil, providing an electrical connection with earth. It is advantageous to use metallic or steel reinforced structures as earth electrodes, primarily serving other purposes including foundations for buildings and poles. This requires early project planning to ensure provision of adequate electrical cross-connections and terminals.
12.2.4
Soil resistivity and resistance to earth
The electrical characteristics of earth electrodes depend on their design and the conductivity of the surrounding soil. The soil resistivity indicates the electrical conductivity of the soil. Normally, it is measured in n-m. Its numeric value represents the resistance of a cube of soil with edge lengths of 1 m between t,rn opposing cube surfaces. The resistance to earth of an earth electrode or an earthing system can be calculated with sufficient accuracy for planning purposes from the geometric dimensions of the electrode and the local soil resistivity. [12.3].
12.2.5
Structure earth, tunnel earth, traction systern earth
An earthing system consists of several earth electrodes that are connected to each other by conductors. The conductive interconnected reinforcement of steel-reinforced concrete structures and the metallic components or other structures are designated as structure earth [12.2]. This includes passenger stations and technical buildings, bridges, viaducts, concrete slab permanent way and tunnels. The structure earth of tunnels is also known as tunnel earth. The running rails of electric railways, which are used as returp conductors and which are intentionally connected to earth, form the traction system earth The traction system earth also includes conductive parts connected to it. Normally, running rails of DC lines are not connected to earth. The term traction system earth i11 this context is not applicable, as it erroneouslv suggests an ea,rth connection. The direct co11 uectio11 of cone! uctive components ,, ir Ii the traction system earth is call<~d direct fraction s:i;sle-111, cadhing. This is cornmon practice 011 AC lines" vVith op('ll t ractirn1 systc111 cartl1iug, co11duetive parts witlt cont ad to earth arc separnL<~d frorn tit(' n•L11rn cirn1i! dmi11µ, 110rrnal operation In 11H'rt11s of ·uoU
__________ 12 Current return circuit and earthing
devices. These provide a temporary or continuous connection only after the trigger
voltage is exceeded. Although no traction system earth is present 011 DC lines, the term open traction system earth is also used there. It signifies the connection of conductive parts with the return circuit or the connection of the return circuit with the structure earth via voltage limiting devices in case of undue high values.
12.2.6
Earth potential and rail potential
The earth potential occurs between the earth elec:trode and remote earth. The resistance to earth of an earth electrode and the current through the electrode determine the earth potential. The traction return current in the running rails causes an earth potential that is designated as the rail potential. The rail potential arises at the running rails and the conductive parts connected to them during both operational and also fault situations.
12.2. 7
Touch voltage
Consideration is given to direct and indirect touching. Direct tov,ch voltage [12.4] refers to possible touch contact to live parts. Protection measures against direct touch contact include insulating enclosures, covers or barriers and sufficiently large distances to accessible surfaces. Indirect touch voltage, in accordance with the standard definition, is present with conductive bodies that are energised only under fault conditions. The voltage between two conductive parts, which can be bridged by a human being, is known as the touch voltage. The metallic enclosures of switchgear, earthing connections and steel-reinforced concrete structures that can carry a voltage are categorised as touchable parts. The part of the voltage to earth that can be bridged by a human being also falls within the term of a touch voltage. Protection devices normally switch faults off so fast that the touch voltage can affect a human being for only a short period of time. The standard EN 50122-1 [12.1] assumes that the duration is less than 0,5 s.
12.2.8
Accessible voltage
The voltage caused by the rail potential during operation is present over a longer period. A distinction is made in [12.1], Table 1 between a restricted duration, typical for railway operations, of 0,5 s to 300 s and a long duration range. The part of the rail potential that can be bridged by a human is designated as accessible voltage in EN 50 122-1 [121] due its long duration. So not to complicate the text, the differing designaLons are not used and the term touch voltage is used below for both the short duration and the long duration events.
J2.2 Terms and Definitions
12.2.9
Overhead contact line zone and pantograph zone
On railway systems with overhead contact lines, the zone "·hose limits are not 0.xceeclc~d in general by a broken overhea.d contact line or by a dewired pantograph, is clesigna.ted in [12.1] as the overhead contact line zone and pantograph zone, respectively. It defines the zone in which protective measures against unacceptable touch voltages are necessary. Such a zone of hazard is not defined for third rail systems.
12.2.10
Return circuit
With conventional AC and DC traction power supply the operating current fiows through the contact line system to the vehicle. The return current, for traction as well as for regenerative braking, fiows from the vehicle through the return circuit to the substation. The return circuit includes all conductors which form the path provided for the return current during operation and in the case of faults [12.1]. These conductors include: Running rails, which conduct the ret..i1-1;.l1--Gl:l-Frn&t-,__ Return conductors, which are laid parallel to the running rails and are connected to the running rails at regular intervals. On DC lines cables laid parallel to the running rails and insulated against earth ---··---·. ··-"·-----a.re ll_~~d to reduce the [~11,,qitudinal rail. voltaCfCS and Jhe Jail potentiaJ:?·.On AC lines, this function can be fulfilled by return conductors suspended on the contact line poles or earth strips alongside the track. The traction power supply systems with two-wire supply like trolley buses or two-rail supply like Metro systems with a 3rd and 4th rail use return current rails or parts of the contact wires of overhead lines, laid as insulated conductors. They are to be treated as energised conductors. In this case, no voltage arises at the car body during normal operation. _ On AC lines, the soil is a part of the return circuiv,is a portion of the return current fiows there as a result of the earthing of the running rails and of inductive coupling. -
-
j
12.2.11
Stray Current
Since perfect insulation from earth of the return circuit of DC lines can never be achieved in practice, part of the return current leaks from the running rails into the structure or earth. This current component, that does not fiow in the return circuit, is defined as stray current.
12 Current return circuit and earthing
12. 3
Basic principles
12.3.1
Return circuit
The traction current flows back to the fe<~der substation via the return circuit. In a direct current railway system, the current flow direction may differ, depending on the chosen contact line polarity. It may even change along a section when a train is braking. From the electrical engineering aspect, contact line ;:i,nd return circuit constitute an inseparable unit. The current drawn to provide the traction power is always proportional to the power consumption. Depending on the arrangement and the cross sections, the portion of the current returning via earth will be equal to between 5 % and 50 % of the traction current in the case of AC traction systems. Conversely, in DC traction systems, measures are taken to keep the current flowing into earth as small as possible to minimize stray current corrosion. The conventional traction power supply systems are shown in Figure 12.1 a-d. The railreturn system (RR) is most commonly used. Special types of return current systems use Booster Transformers (BT) and Auto-transformers (AT). In BT systems, the insulated return conductors are connected to the running rails at the midpoint between the BT locations and are almost at rail potential. They carry the largest part of the return current that is also conducted through the running rails and the soil. Alternating currentlines with ATs use a double or multiple overhead contact system voltage using an energised return circuit known as a negative feeder. In sections with railway traffic, the running rails and the soil conduct the traction return current in the same way as the rail return system (RR). Where the energy is supplied in mv,ltiple-phase systems, e.g. the feed system with 2 x Un, as described in chapter 1, three conductors are used to supply power: the contact wire and return conductor - usually called a negative feeder - and the track (see Figure 12.1 c). Theoretically, outside the auto-transformer section currently under load, no current should flow through the track. In practice however, studies [12.5] have established that up to 10 % of the load current will flow through the track. As already explained in clause 2.5.4.4, it is preferablethat the rails are also used to provide protection against indirect electn,cal contact. This protecti\·e mechanism is achieved by connecting the conductive parts with the running rails. Here we distinguished between direct traction ear-f;hing, where the conducti\·e parts are directly connected to the return circuit, and open trn,ction earthing, where the conductive parts are connected to the rails via volt(J,ge lirniten; or short-circuiting dev'ices. In such cases, this connection is established either temporarily or permanently if a fault occurs and a set threshold voltage is exceeded. In alternating current railway traction systems, traction earth is considered to include the running rails which conduct the return current and are earthed deliberately, as well as all conducting parts electrically connected to these. The rail-to-earth potent'ial dc'scrilwd above varies with location, ti111e and load conditions_ Humans or anin1c-1ls can conw into rnntad. with (:ither the foll or partial potential Tlwn:forc, to dimina.!:P dang(~t to j)(!opl<'. th(' mil-Io-earth put<'lll ial must not exceed
G27
12.3 Basic principles
a)
00
Substation
Contact line
Return circuit
b)
Substation Return conductor Contact line
Return circuit
c)
Substation
Boostertr ansformator Return conductor
Contact line
d)
Substation
Autotransformers
II
Negative feeder
----------------------++------------....,,..-------<>-t-----,:Contact line
Figure 12.1: Track return current on AC railways. a) Return circuit via running rails b) Return circuit via. running rails and return conductor c) Booster transformer system d) Auto-transformer system
.. 12 Current return .circuit and earthing
628 --··-·---···------
10~0
-
~
'-
..., "'\:,
t
500 ~400 :::i 300
~ ~ 200 ~
'
- --
£ 100 'iii
(/)
E
CL
70
~
~·-
50 40 30 0,02
~
''
(.)
0,10
I-
,_,__
.
--
f---
.
"h
.c:
~
f-1-
1---
DC in accordance with EN 50122-1
- --
~
- -
-
-) 1D
- -
\.k:c..
AC in sccordance with HD 637 S --
,I
' I
I
11
I
AC in accordance with EN 50122-1
10
Duration t - - - - - -
1111
100
11
s
1000
Figure 12.2: Permissible touch voltage Uper as a function of current flow duration t according to EN 50 122-1 and HD 637 Sl.
Figure 12.3: Equivalent circuit diagram of a touch circuit. ZB body impedance, lg current through body, Ra1 shoe resistance, Ra2 local ground earthing resistance
the permissible limits according EN 50122-1 [12.1]. In the future, standard HD 637 S1 [12.10] will apply to the AC three-phase installations of the high and medium-voltage areas of electric railway substations. EN 50122-1 applies to the immediate vicinity of the electrical railways themselves. Figure 12.2 shows the maximum permissible touch voltage Upei between the hands and feet of human beings depending on the current duration as defined in EN 50 122-1 and HD 637 S1. When these values were evaluated, additional resistances were not taken into consideration. The standards do not specifv step voltage values, as these would be greater than the permissible touch voltages. Danger to persons may occur in railways due to too high rail-to-earth potential if the touchable part of this potential exceeds the permissible touch \·oltage. This accessible part of the rail-to-earth potential difference is shown as Uab in Figure 12.5 and as Uab/UTE in Figure 12.19. As can be seen clearly from these diagrams, Ua 6 /UTE will be well below 1 in almost all cases. In worst-case situations, Uah CcUl be equal and identical to UTE· The accessible voltage would only be equivalent to the perrnzssible touch voltage Uper (i.e. Ua 6 /UTE - 1) if it were applied to bare hands and feet. In practice, however, any circuit formed when the higher-potential parts are touched usually contains additional resistances as shown in Figure 12.3. For example, persons working in railway areas, Ra is the surn of Ra 1 ( e. g. shoe resistance) and local earthing resistance Ra2 - Figure 12.4 shows the touch voltages which would be permissible if the additional resistances within the touch czrcui,t are taken into account, for typical assumed shoe and ground earthing resist;-mces in railroad vicinity, as functions of the current flow durations. These values arc noticeably higher than the touch voltages permissibl<\ for the unprotected human body. In [12.G], shoe sole n:szst,o,nees of 1:3 diffcn,nt t \'JWS of sol<~ \\'it h wdcled or glued shoe
629
12.3 Basic principles
V
1500 e)
c)
100 +-----+---+----+---------r--~--- b) - - + - - - l a)
50+-----+---+----+----+---+------+---l 0,05
0,1
0,2
0,5
2
5
s
10
Figure 12.4: Maximum permissible touch voltage acc:orclmg to HD 637 S1 assuming additional resistances iu the touch circuit, plotted as a function of the current flow duration t. a) Ra= 0, i.e. Uab = Uper; b) R, = 750 n with Ra 1 710 f:), and i?E = 27 n-m; c) Ra = 1750 n with Ra 1 1315 f:), and QE = 290 n-rn; d) Ra 2500 n with Ra1 1000 n and QE = 1500 n-m; e) Ra = 4000 n with Ra 1 3960 n and QE = 27 n-m
inner soles after two to seven hours air drying were measured, with a large number of random samples being taken. Apart from an inlay leather sole with a resistance of 350 n all other measurements showed sole resistances of between 4,4 kn for moulded PVC soles and 9,4 Mn for moulded PUR soles. The specifications made for railway installations in EN 50122-1 differ from those set down in HD 637 Sl. Although both of these standards refer to the international standard IEC 60479-1:1994, for instance, the permissible touch voltages stipulated for single-phase AC railways in EN 50122-1 are up to 200 V higher than stated in HD 637 S1 for the current flow duration range up to 0,2 s, and are between 20 V and 5 V lower in the 1 to 10 s range. In EN 50122-1, the permissible touch voltages for current flow durations of 0,6 s and longer are also termed per-rm:ssible acces.sible voltages. As can be seen, a distinction is made between dfrect current and alternating current rnilway.s. In contrast to HD 637 S1, which specifies permissible touch voltages of 80 V for a IO-second current flow and 75 V for longer current flow durations, EN 50 122-1 defines permissible touch voltages for limited current flow durai,ions of up to :300 seconds. According to EN 50122-1, the permissible long-term touch voltage is 60 V for AC raihvay traction systems and 120 V for DC railway traction systems. For AC railways in (12.7] and (12.8], a factor k is used to define an accessible voltage Ua which is not identical to Uab· This factor takes into account the facts that generally additional resistance.s are present in the !,ouch ciTc11,it and that, in practice, usually only a fraction of the potential difference generated bct\veen the rail and earth \\ hen a current flows can be accessed. This factor is expressed by the ratio: ( 121)
}2 Current return circuit and earthing
Figure 12.5: Potential gra-
S1
dients and accessible voltages in the vicinity of a track. UTE track-to-earth voltage, Uab = accessible voltage ( no-load touch voltage), UaP = accessible voltage with voltage-limiting prov1s1ons, S1, S2 voltage-limiting prov1s1ons, e. g. earthing electrode strip bonded to the rails.
In the references quoted, values of 0,3 to 0,8 are given for k. From earlier versions of DB's (German railway) directive Gbr997.03 [12.9], we can deduce that a value of k = 0,5 is recommended. Figure 12.5 also illustrates the fact that it is usually only possible to access a fraction of the voltage when touching rails or tracks, which are at a higher potential than traction earth. · In individual cases, it may be necessary to introduce equipotentig,lJ2QD.ding. meas_UIT!L in order to reduce the expected accessible voltage Uab· Such equipotential bonding is achieved by electrical connections which ensure f.hat external conducting parts are kept at the same or nearly the same potential as the accessible conducting parts of electric operating equipment which may become live in case of a fault. Some electric railway operators even require mandatory equipotential bonding provisions (also refer to Figure 12.5). For a single-phase AC railway as an example, Figure 12.6 shows a synopsis of return current and traction earthing circuits.
12.3.2
Rail potentials
12.3.2.1
General aspects
The track-to-earth voltage Un:. is defined as the voltage between the track and earth. Figure 12.19 shows the characteristiC' curve of the track-to-earth voltage as a function of the distance at right angles to the track. In the direction of the track, the potential UrE drops to only low values at points outside the transition length llrans· Figure 12. 7 shows the track-to-earth voltages to be expected per kA traction current on a feed section which is 24 km in length. The value of UTE is determined by the tract.ion current, by the r,ffective k)akance per unit length, the distance l lwhve('ll Lli<' si1l>statio11 and the load, and by the earth n!sistance RE of the suhstatio11.
12.3 Basic principles
631 ,,,,._;;:--=--:<,
II '·v ,\ ~ - ~ - - - - - - - - - - - - - - - - ~ 1 ' , - - - - " ' - " " ' " " ' - i l ~ ~ \ - - - - ~ · , - Overhead contact line ! trc ___ coupling 1 between 1 -----..-----.----..-----.-----.--+1-----'-'--'-----=-=------++-,-----+-- Return conductor I - - ! Ill I ~HL and Rq, I I \ '- ~ _ ~ , , J Traction vehicle
I Ussl I I I I
I I I I I I
substation
--
Connection to other conductive parts
I I UTE I I I I
_ _ , =/ - / - / . - T - tre - E - RC
/
I
/
Running rails
'\
(track)
I /inductive\ I 1 coupling / 1 1 Y TE I track11 earth 11 \\ II
I
RE
t! tre
Inductive I coupling I between I OHLand I RC / /
ii
\\
II //
\\
I I UTE I I
y TE
I Earth
Figure 12.6: Current return path and traction earthing of single-phase AC railways. RE = earthing resistance of the protective earthing system of the substation. Substation
Traction vehicle
50
ltrc
i&
I
I
30
!:!.IE.20
\
lire 10
0
I ,L____ "-------
0
4
_/
12 8 16 Distance-
20 km 24
Figure 12. 7: Ratio of track-to-earth voltage to traction current, along a doubletrack line without return conductor, with an effective leakance per unit length of 2 S/km and substation earth resistance of 0,2
n
If the voltage measurable between a point P on the earth's surface and earth reference potential should be determined, this is obtained by plotting the ratio UPrc,/UTE against the distance a from the track as shown in Figure 12.19. For many practical applications, however, it is important to know the voltage UTP occurring between the track and a point P on the earth's surface. The ratio Urp /Urn of this voltage relative to the trackto-earth potential is also plotted in Figure 12.19. This voltage increases with distance from the track ctnd reaches its maximum value, which is equal to Urn, at the edge the reference earth. The part of the track-to-earth voltage, which can be measured 01 touched between any two points, constitutes an accessible voltage Uab· Two examples of this quantit~ are shown in Figure 12.19. The track-to-earf;/1, voltage of direct-current railways can be calculated using equation (12.9) and that of single-phase alternating current railways using equation (12.19). If the respective line is not terminated with an impedance equal to tile surge illlpedance of Z 0 , but with a diff<)rcut va.ltw of ZA, tlwu, for sPctions where ti!(' t·xpo11cI1tial portion has already dccawd, t.li<~ ( 1ack-Lo-cartl1 vol tagc at the load lora 1.irn1 is ded t1cc·cl from
_____________ 12 Current return circuit and earthing
632
equation (12.10) as
ZA Z 0 I,rc. -UTF~ = -, ZA +Zo (1
&)
(12.2)
J\t a substation with an earth electrode system of earth resistance Z 8 , the voltage is calculated by the equation:
u1'~ = I
-
b
-1.rc
z .z .z -0 -E
-A
Z Z + -E Z, (Z + -0 Z ) -A-0 -A
(1
k.)
(12.3)
Example:
How will the track-to-earth voltage as derived in the example in clause 12.4.3.2 for YTE = 1 S/km, which was determined as UTE = 75 V per kA traction current, be decreased by equipping the substation with an additional earth electrode system having an earth resistance ZE =RE= 0,1 n? In clause 12.5.5.9, the surge impedance was calculated as Z 0 = (0,213 +.i 0,18) n/km. Z A was assumed to be equal to Z 0 , giving the result k = 0,46. With this factor, the track-to-earth voltage at the substation is calculated to be 33 V /kA. If the substation earth resistance is assumed to be 0,2 n, the track-to-earth voltage at the substation will be 47 V /kA.
12.3.2.2
Track-to-earth voltage in operational conditions
In the following section, the operating current drawn by a traction vehicle is termed the traction vehicle current Itrc· Traction vehicle currents in general railway traffic electrified by AC systems can be as high as 1000 A. The maximum traction unit current drawn by the ICE 1 high-speed passenger train is 850 A. For the ICE 3 model, drawn by two traction units per train, a maximum value of 1450 A is expected. In single-phase AC railway systems, the highest trnck-to-earth voltages for the given currents will occur where two trains each drawing the maximum traction vehicle current meet on a double-track line. Where two trains accelerating in opposite directions meet, the resulting track-to-earth voltages may persist for periods of one minute or even longer. In such cases, as shown in Figure 12.2, the permissible touch voltage for current flow durations of up to 5 minutes will be Uab = 65 V. As a consequence the rail potential which may lead to danger to people must not be allowed to exceed UTE = 65 kV where k is taken from equation (12.1). For the standard k-value used by German railways, a rail potential of 130 V would be permissible. For this worst-case scenario that two trains are accelerating and drm-ving the maximum current of 850 A each, and assuming k 0,5 and Uab = 65 V is permissible, the permissible ratio of track-to-earth voltage to traction current occurring for several minutes would be 76,5 V /kA according to (12.2). On double-track lines with a leakance of 0,1 S/km per track, this value will not be exceeded provided that the pole earth resistance of the poles bonded to the rails does not exceed 106 ft Figure 12.8 shows relevant practical exarnples of how the resulting track-to-earth volt.ages are related to pole earthing resistance values. For conditions involving otherwise unchanged parameters, the use of return conductors reduces th<~ trn.ck-to-earth voltage C(msid<~rably. T'his effect can be clearly observed in
!~,3 Basic principles
633
100
V kA 80
70
/"'
60 UTE
T;;;;
50 40 30 20
I
I/
I / /
----- ----
/
v----
---
------
---
40 60 80 Pole earthing resistance RM _
20
100 _,,_
a
b
n
120
Figure 12.8: The track-to-earth voltage, in relation to the traction current at the load location on a double-track line with a leakance per unit length of 0, 1 S /km per track, plotted as a function of the pole earthing resistance, assuming there are 16 poles per km of railway line. a) without return conductor b) with return conductor type Al 240 Rrvr pole earthing resistance, Urn/ ItlC relative ratio track-to-earth potential
u I' {\)
UTE 40
.\ '}
( ;
U,
t------<+--,+'-'- ~ - - " l r - - + - - t - - - - t - - - t - - - - - - - 1
ltrc
5
10
15
20
25
30
35
40
45
Distance - - - - -
Figure 12.9: Characteristic curve of the potential gradient of the track-to-earth voltage in track direction, related to a traction current of 1 kA, plotted for different track-to-earth leakances per unit length YfE and pole earth resistances Rrvr. 1 without return conductor, Yf 8 = 0,01 S/km, Rrvr = 100 n 2 without return conductor, Yf 8 = 0,1 S/km, RM= 100 n · 3 without return conductor, Yf 8 0,1 S/km, RM = 20 n 4 with return conductor, Yf 8 = 0,01 S/km, Rrvr = 100 n 5 with return conductor, Yf 8 = 0,1 S/km, RM = 100 n 6 with return wire, Yf 8 = 0,1 S / km, RM = 20 n UTE/ Itrc relative ratio track-to-earth potential
the graphs shown in Figures 12.8 and 12.9. For the expected traction vehicle currents of 1130 A, clanger to people can only be excluded for lines comprising ballasted track and without ret,un conductors if the pole earthing resistance does not exceed 6,5 n. Since considerable technical effort is required in order to achieve such low pole earthing resistances, the use of return conductors is the most economical solution for keeping track-to-earth voltages within acceptable limits on railway lines with heavy traffic: loads. Measurements carried out on a double-track line vvith concrete slab permanent way of leakance 0,01 S/km per track have shmvn a good correlation with the calculated , aliws. For Rrvr = 8 S2 and 16 poles per kilometre, values of 30 V per kA traction currrnt were observed. The introduction of return conductors would reduce this ratio to 20 \ /kA.
i: I
_____________________________1;2 Current return circuit and earthing
63--1
1000 V 800
+---,~r---i-----,--~-i----i-----i-----,i----1-·..---1
5
10
15 20 25 Distance-----
30
35 km 40
Figure 12.10: Rail potential along a double-track railway line, plotted to illustrate the extent of the dangerous earth potential gradient area; leakance per unit length 0,01 S/km, mast earth resistance 100 n. 1 potential gradient area if there is a short circuit at kilometre 12,5 2 potential maxima for a short-circuit location moving from one substation to the next
12.3.2.3
Track-to-earth voltage in the case of short circuits
In the case of short circuits, the magnitude of the short-circuit current and the related track-to-earth voltage is determined by the impedance of the substation feed transformers and the contact wire impedance. However, the track's leakance per unit length and the pole earthing resistances are also decisive factors for the rail potentials that can be expected in the case of a short circuit. Figure 12.10 shows the longitudinal voltage/ distance graph for an unfavourable case which has an elliptical potential gradient area. It was assumed that a short circuit has occurred at km 12,5 on the line, which has a total length of 40 km. From this graph, we can determine the magnitude of Urn when the short circuit occurs at km 12,5, the length lu of the area in which UTE is equal to or greater than 700 V, and the location of the most unfavourable short-circuit positions where the highest voltages occur between the fault location and the substation. The low UTE values observed for short-circuits near the substations are due to the assumed low protective earthing resistance value of 0,2 0 and the larger number of parallel tracks in the vicinity of the substation. The ratings of an overhead contact line installation of type Re 330 were used in the calculations on which the graph is based. Reference [12.8], discusses the potential hazards to be expected in the track area in the case of a short circuit as illustrated in Figure 12.10. If the short circuit duration is 0,07 s, a \-alue not normally exceeded in AC operations, then the probability of an accident due to electric shock is equal to zero, irrespective of whether return conductors are installed or not. For a longer short-circuit duration of 0,1 sand assuming YfE = 0,1 8/km and R\r = 200 0, the probability of dectric shock is 1,31 · 10- 5 for people working in the railway zone for four hours a day ou twt~nLy davs per year. If all personnel working in
12.3 BasicJ>rinciples
635
the railway zone are obliged to wear protective shoes with PUR soles, potential hazards can even be excluded for longer short-circuit durations, lower leakauces 1~{,E and larger pole earth resistances RM.
12.3.3
Safety
The protection of human beings against electric shock has highest priority. To guarantee safety of persons, the touch voltages during normal operation and in fault situations must not exceed the permissible voltages in accordance with clauses 12.5.2 and 12.6.2.1. In order to fulfil the protection criteria, a satisfactorily dimensioning of the return circuit and the earthing system is necessary. The return circuit must conduct the traction and regenerative braking currents, as well as the short-circuit currents during faults, to the substation at low impedance. So the longitudinal rail voltages and therefore the track-to-earth potentials are limited and the permissible touch voltage is ensured. Design must ensure these features. T ~ rail8-J3110uJd be used.. ~o conduct the Ieturn current* 0 s.JaL_as _possible. and they should be through-com~_~<::ied atlow impeda!l.£~- Rail bonds, track bonds and track rel ease·-ci 1:5:: u it b on dsJJ!~ t con cl UC t t l]g_LeLilflLCJJJI~I!t_§~.".'.~J!J_LS_J2111]2Q~!-l:,.QLJJ1 e upgrade of~ti~1g syst~s, C~bles are laid parallel tothe runningrails to SUPJ:}lementthe return circuit. Interruptions- to the return circuit are ~10t permissible, because. touchable components could become live. Tl1;-;ppropriate arra1-;g;;n~)-~t,- ~f the retun1 circuit and the resulting return current distribution reduces the interference and magnetic .fields in the vicinity of the railway lines. The permissible voltage val'lles specified in [12.1] and [12.10] for electric shock hazards for humans are based on comprehensive examinations of body resistance and the effects of body currents [12.11]. Both standards specify different values for permissible touch voltages because of the consideration of varying footwear, insulation of the location and probability of ventricular fibrillation, Other values have been derived for low voltage applications [12.12], Figure 12.3 contains the permissible touch voltages depending upon the duration of interference.
12.3.4
Security
Security problems may anse from interference by railway circuits on railway-owned and third-party installations due to magnetic fields and the current return through tracks and earth during operations. They are quite different from tlircc-phase AC public supply. With respect to the interference caused by traction supply circuits the following should be considered the ohmic or galvanic interference - the ind'lf,cfzve and capacitive znlcr:fen:nce and - electric and -mru;11,etir: .fields. The galvanic iuterf'<,re11c<~ is caus<~d by conductive connections Lo Lil<' 1d,u111 circuit. Capacitive int<,rfon't1c<· plays a 111inor rol<· oulv in railway dec:Lric pow<'r supply. Iucluctive
__________________
~-:__ 636
_______12 Current return circuit and earthing
interference and magnetic fields, however, are important in the case of AC power supply systems. The magnitude of interference depends on the self and mutual impedances of the overhead contact line arrangements. The magnitude of interference follows the distribution of the currents. Therefore, the current flowing through earth represents a quantity to measure the degree of interference. The design of contact line configuration, aims at limiting the return current through earth and reducing the interference in the vicinity of the railwa,y. The interference concerns railway owned as well as third-party installations. Depending on the sensitivity of the devices, operational impairment may occur. Details on analysis and acceptable levels are discussed in chapter 13.
12.3.5
Stray current corrosion
Metals in contact with an electrolyte such as humid soil show chemical reactions if currents flow through the connection always in the same direction. Therefore, the DC currents flowing from the tracks to the earth and returning to the substations, the stray currents, cause stray current corrosion at metal structures in the vicinity of the DC railway. The aim of contact line design is to avoid stray current corrosion at railwayowned and third-party installations. This can be achieved by limiting the stray currents by adequate design of the return circuit, in particular by insulating the tracks from the earth or structures, e.g. tunnels and viaducts, and by planned maintenance to identify short-comings and repair defects within the return circuit [12.13, 12.H, 12.15, 12.16, 12.17]. A low longitudinal voltage drop in the return circuit and good insulation of the rails from earth can limit stray currents substantially. Since the longitudinal voltage drop depends on the resistance of the return circuit and the distance between the substations, stray current protection can determine the number of substations. Stray current protection comprises third-party installations, railway-owned, steel reinforced tunnels and viaducts as well as at-grade line equipped with reinforced concrete slab permanent way or similar permanent way designs. The criterion of 100 m V has proved to be relevant and easy to verify [12.13]. For DC railways a good insulation and strict separation of return circuit and earthing installations are required. Details are discussed in clause 12.5.
12.3.6
Common features of and differences between AC and DC railways
Use of the running rails as return circuits is a common feature of AC and DC railway systems. The measures for earthing and bonding however, differ fundamentally. In DC railway electrification systems, the running rails are laid with a high impedance to earth and to earthing systems, to avoid return current leave the running rails as stray currents, causing corrosion of metallic components in dose contact with the earth. Items such as pipelines, cable screens, steel reinforced foundations of buildings or poles, reinforced tunnd structures, bridges an
637
12.3 Basicpriuc:iples
---111
return circuit
buildings
viaduct
tunnel
at grade lines
Figure 12.11: Simplified circuit diagram of return circuit and earthing of DC traction systems.
return circuit
buildings
viaduct
tunnel
at grade lines
Figure 12.12: Simplified circuit diagram of return circuit and earthing of AC traction systems.
Voltage drops occur in the running rails along the line, causing rail to earth potentials during normal operation and with short-circuits. Since no earthing connections are present, there is a risk that the permitted touch voltage will be exceeded in case of high currents and long feeding sections . The danger arises on surface lines in the open against earth and in tum1cls, on viaduct!; and in stations and substations against the structure earth. Suitable measures for the arrangement of the track rehLrn circuit arc specified in [12.13] and detailed in clause 12.5. In addition to ohmic voltage cir-ops arising in DC railways, alternating current causes inductive voltage drops, which are almost the same magnitude as the ohmic component at the operating frequency of IG,7 Hz and more than double that value at 50/G0 Hz. This, together with the longer feeder s<\ctions, leads to significantly higher rail potentw,ls than vvith DC railways, i11 spite of the smaller operating currents. To restrict. the rail potentials to acceptable values, it is necessary to connect the return circuit to <~art.It, i.e. to connect the running I ails and additionaJ return conductors along, the track cttl(l in the substation. Figure 12.12 illustraL<·s Llw necessary co1wectio11s lwtw<\Cll tit<' return circuit and the earthing systetns for AC railways, descrilH:d in rnorc detail in [12 lj and clause~ 12.G. Th<~ c,1rtltit1g of t.lw n1tlllittf.!i mils is i11d<'lH't1de11t of the t.rnction pow<'r s11pplv c;\·sl<\tll
638 ~----------------~-------------
12 Current return circuit and earthing
Apart of the return circuit, current flows through the earthing installations of the buildings and through the earth, due to the earthing connections of the return circuit. This current has undesirable inductive and magnetic field interference on equipment alongside the railway line and can cause disturbances in electronic equipment.
12.3. 7
Measurements
Reliable information for the planning of electrical installations in many cases is only available from measurements. The design of earthing installations requires information relating to the soil resistivity to enable calculation of the resistance to earth of foundations or earth electrodes. If existing earthing systems are used, it is recommended that direct measurement of resistance to earth is undertaken. Together with the planning values for the operational and short-circuit currents, the touch voltages can be calculated. This is required as a design value for the assessment of safety of persons. During the construction phase, the planned earth connections must be inspected before they are covered with concrete. The measurement of the earth resistance of subsystems is recommended if the design has given critical values so corrective measures are possible in due time. During the commissioning phase, verifications of safety of persons and operational reliability of the installations are necessary. Measurements provide meaningful information. They are a significant contribution to the rapid technical approval of the installations. During the commissioning phase of DC railway systems, measurements are necessary to testify the effectiveness of stray current protection measures (see [12.13], Appendix A). Also during the operation of DC railway systems, measurements are necessary to check the measures against stray current corrosion to be able to react if necessary. Such measurements also support the permanent supervision of safety of people in electrical installations.
12.4
Earth as a conductor
12.4.1
Soil resistivity and conductivity
Earth is considered to include all types of soil and rock that make up the Earth's external crust and contributes towards conducting currents. The soil, like metallic conductors, presents a resistance and conductivity to the circulation of currents, depending on its physical and chemical properties. When a voltage is applied to a conductor with uniform cross section and homogeneous material, the determination of its resistivity and resistance is a simple task. However, when dealing with current conduction through the earth, the analysis becomes very complex, because of the huge dimensions of the earth as compared to the metallic conductors and the great variation of its characteristics_ For example, experimental tests made with red clay soil indicated that with only 10 % moisture content, the r<\sistivity ,vas over :30 times that of the same soil having a moisture content or a.bout 20 <;{_ For v,1l1w~.; ahow 20 %, the resistivity is not affected
12.4Earth as a. CO!lduc:tor
639 50
Table 12.1: Soil resistivities Type of soil Sea water lVIarshy soil Loam, clay, humus Saud
Gravel Lime stoue Sand stone Weathered rock Granite Moraine
Soil resistivity (inn m) 1
5
cl()
50 350 200 2500 2000 - 3000 350 2000 3000 up to 1000 ~ 3000 50000 up to 30000
%
t
w
40
,_ ,___
__
.9, -c::
30 , _ ,
·tf
--
~~
%,'. ~'.,'.
?mi
-
1/,Q
--
-
C Ql
;20 :0 C1l
<-<--~
.D
ct
m
v~
<--
1:0,W-
10
=
~~
I%&,;
i,/.W, r,;
V///h
25
'l
~~
~
WJ~
?,
~~~ ':<~ 1////"/,/,
10
25
~ V,
,'//2
50 10QQ.rn5 DO
Soil resistivity PE - - - -
Figure 12.13: Histogram of soil resistivities in the vicinity of railway lines according to (12.18].
1-a-1
a
1-a~i
Figure 12.14: Function of an earthing tester.
too much but below 20 %, it increases rapidly with a decrease in moisture content. As defined in clause 12.2.4 the soil resistivity is expressed in n-m, the soil conductivity in S/m. Resistivities of typical kinds of soil are suited around the values indicated in Table 12.1. Figure 12.13 shows a histogram of soil resistivity values measnred along 6000 km of railway lines in Germany [12.18]. The majority of measured data is below 50 n-m, the statistically expected value being 25 n-m. Reference [12.19] reports on s_oil conductivity of 3,7 · 10- 4 S/rn which is equivalent to a resistivity of 27 nm and very close to the above mentioned expected value of 25 nm. With the latter value a current penetration depth of 800 m results from equation (10.20) for AC 16,7 Hz and of 450 m for AC 50 Hz. The most frequently used method to determine the soil resi8tivit;i; depending on the depth is tJie fouT-poi1,,t ·method, also called Wenner method [12.20] where an earth megger- [12.21] is used (see Figure 12.14). The four rods arc arranged with the same spacing a; five measurements with the spacings a, = 2 m, 4, 8, lG and 32 m are carried out. For each tll<'asmcment a current I is injected between the prnh<~s C 1 and C2 and the voltage betvvc<:ll the points P 1 and P 2 is rrwasured. vVith inncasing spacing a the measured soil n~sisi ti vi t, applies for greater depths since the current flows through soil strata in greater d<~pLh. Tl1c prniics C 1 11ml G2 must be cylindri('al and short, such that their resistance is high in t<'lation to that of the soil.
12 Current return circuit and earthing
640
The soil resistivity QE
=
QE
results from
2 rr · a · RE
(12.4)
where a is the distance of the probes and RE the recorded resistance.
12.4.2
Track-earth circuit
12.4.2.1
General
Tracks are the permanent ways and structures on which track-bound vehicles travel. They are placed on a ballast layer or embedded in road, or concrete structures. The embedding is a foundation for the track and assists keeping the track in the required location. The combination track and ballast are often described by the joint term superstructure. The upper limit surface of the substructure, i.e. the top level of the formation is also called the subgmde. The electrical resistance between the rails of a track and earth is called the mil-to-earth resistance. This resistance which describes the galvanic or conductive coupling of track and earth depends on the properties and condition of the superstructure between the running rails and the earth. The essential characteristics of the superstructure are: the type of superstructure, i. e. type of sleepers and track fasteners used e. g. sole plates, including insulating pads between rails and sleepers; the bedding of the sleepers, e. g. in gravel or sand ballast, in a road, on concrete or, as is now used for tramways, in turf. As explained in 10.1. 2, the condition of the track embedding is mainly determined, . from the electrical engineering aspect, by: - the degree of contamination, and - weather conditions such as damp, rain and frost. More recent measurements have proved that the characteristic variations of the railto-earth resistance of tracks with concrete sleepers were in the range of 0,4 to 2,5 D-km corresponding to a leakance per unit length of 2,5 to 0,4 S/km in summer weather conditions and 1,5 to 17,5 D-km corresponding to a leakance per unit length of 0,67 to 0,06 S/km in winter conditions [12.22]. Extensive measurements and analytical studies of concrete-sleeper track superstructures have shown that the rail-to-earth resistance is determined to an extent of 90 % by the type of sleepers and ballast. The remaining 10 % are a function of the substructure and the subsoil in the vicinity of the track [12.22]. Recent mil-to-earth resistance measurenients carried out under varying conditions with normal operating currents and with short-circuit currents have also led to the conclusion that the rail-to-earth resistance is virtually independent of the currents flowing to and from the track to earth within the entire range of currents possible in an electric traction network [12.22]. This means that the r;alvanic coupling of any given superstructure is also independent ,vhether the railway is powered by direct current or by alternating cnrrent. The ru,i,l-/;o-earlh '/,'/11,JICdo,nr:e of single-phase AC ra,ilway systems is a complex vectorial q11ant.ity with ,\II ,rngl<' of lwtw<~(~ll 1° ,wd 3° [12.2:3]. B<~<'a.11se of this, the very small
12.4 Earth as a conductor
·---------·-------------------------- - - - - -
641
L +x ftrc:___.._
YrE
I lTE
-- ··-Rr
RT
RT ' .
YTE
·.
]YTE
A
'
Rr -
YTE
'
I
-/
!!..:r..
'/ YTE
YTE
contact line
!' ,
1 electric loa d
RT
Rr
,
'• ~
~be·
.. '
substation
R.l
··X
:
IYrE
-- track YTE
earth
Figure 12.15: Model of the galvanic coupling between a railway track and earth.
reactive component is ignored in practice and the resistance \s also assumed to apply, as a purely ohmic quantity, in calculations for single-phase AC railways. According to DB's directive 997 [12.9], the rail-to-rail resistance of a track is the resistance between the two running rails. High rail-to-rail resistances are required to_e~e ... reliable operation of track release systerns. The rail-to-rail resistance can b~;:1ffec:tec:Lby ""'-= ~-- --~- --~--- -~- , -, - - -,-;,_ ,_,, ------~-,-----~--~~~"'-- .the 'typ·e of insulating pa·as placed between the rail and. the sole pl;;i,t~E>: If the insulating pads of both running rails liavethe.sai'ne ele;;ETcaf~~teristics, the superstructure is considered to be symmetrical from the electrical engineering aspect. High rail-to-rail resistances can be achieved by installing good insulating pads. If the superstructure has different insulation characteristics between each running rail and the sleeper, it is termed an asyrn.metric superstructure. The above-mentioned DB directive specifies ~ a *rail-!&:rl1iLresist.axtG.e~oLatJe.a$tl,[},Jllrn:i "~for symmetric a! supers true tu res, ~1:1~L5ttl~,g~J,,JLH:JfxnJQt.{l~~~UlJILrnftriG §llJ) ern_tI1!.CJ_t1!·~3. . if tf1ese are to be usecl for audio frequency track release circuits. Figure 12.15 shows a model circuit of the galvanic coupling between track and earth. In this model, the distributed or continuous quantities longitudinal resistance per unit length R~ and leakance per unit length 1 between the rails and earth are represented as discrete resistors. By generally accepted definition, the resistance of the subsoil bet-ween the individual connecting points of the resistors \\·ith the soil has been assumed to be zero. ="•"""'"'-
-
. -
--
I
ii
'
~;,E
.! II
12.4.2.2
Track-earth circuit of DC systems
In DC systems, the rails are insulated intentionally from earth to avoid stray currents as far as possible. However, depending on the actual condition of insulation and the resistance of the superstructure, a part of the traction current Itrc flows through the earth back to the substation. Figme 12.15 shows a simplified model of the qalvanic couplinq between the track and earth with a single substation supplying energy to an electric traction vehicle. Iu reality, an elc~ctric railway system on which a larger number of trains are running currently, will receive its energ~, supply fro1t1 a multitude of substations. For this reason, either the individual loads or the railway line load per unit length are taken into consideration wlwn discussing the currents and Yolt agl's between track and C'arth. Th() railway line toad per lll1it. length is ddinecl Ii\ equal ion ( HL17). Calculating <'.arth cm-rents and t.rnl'k-to-eartl1 voltag<'S is a ,·ornpl:·x prnrHhtH' . the n~sults df'!)C'lld 011 trnin ;-rnd lmvl
, I
'·'
,,
ii'_I.
l,. I
12 Current return circuit and earthing,
642
Table 12.2: Earth current and track-to-earth voltage for an example with UIC 60 rails for a traction current of 1000 A. Leakance
Surge impedance Zo
Y'
n
S/km 2 1 0,1
0,0866 0,122 0,387
Propagation constant a I/km 0,173 0,122 0,0387
I,
Earth current 10 km L= 5 km A A 290 228 088
176 131 046
Track-to-earth voltage at x = 0
I
/
V
43 61 194
(_,)
L,__ v6 combinations existing at any one point in time. For this reason, only some fundamental conclusions will be made here based on the model shown in Figure 12.15. According to reference [12.23], the assumption is made that the track leading up to the substation and away from the traction vehicle is of infinite length. The earth wrrent IE is (cf. Figure 12 .15)
(12.5) In this equation, a is a propagation constant of the dimensions (length) 1 . It is calculated by the emgition. (\ , \ ( ~1.. \ · ( )
a=
C
VRlr ·Y' .
1.· -
(12.6)
TE
.\.._,,.,_;' ~c,·=·
At the position of the electric load, the voltage UTE occurring between track and earth is UTE
= UtrcZo/2) e-ax
(12. 7)
whereby Z 0 is the surge impedance, which is calculated as
Zo
= JRly/YTE
(12.8)
Example: For a single-track DC railway line, determine the current which flows through earth midway between the traction vehicle and the substation for L = 5 km and L = 10 km, assuming the leakance per unit length to be 2; 1 and 0,1 S/km. The rails are type UIC 60. In addition, the track-to-earth voltage should be calculated at the traction vehicle location if the traction current drawn is 1000 A. From Table 10.6, we obtain R' = R~ = 0,015 D/km for a single track having UIC 60 rails. This leads to the results presented in Table 12.2. In the case of a leakance per unit length of 0,1 S/km, obtained by good track-to-earth insulation, the rail-to-earth voltage, if fully accessible, at the vehicle location and at the feed point would be considerably higher than the touch voltage permissible for 300 s, which is· only 150 V.
The graphs shown in Figure 12.16 are obtained by calculation of the entire range of values of the earth current and the t'l'!Lck-to-earth voltage between the sub-station and the point where the energy is consumed and these values plott<\d as a function of the distance. According to the publication [12.23] and using the above co-ordinate designations, the rail potential is calculated by
(e-n:,, - <,--n(/,-.i:l) [; r.Tb, - (ZOI t re /')) ~ · ·
z·- 0 I trc(\ -nL/'2 Slrl . Il [O' (L/2 1
-
J )]
(12.9)
J2A Earth as a conduct.or
643
ss
vehicle
L
+x-------x
Figure 12.16: Track-to-earth voltages UTE and track currents h in a DC railway line with a single feed substation and a single load.
and the rail currents by I
T ~
(Itrc / 2) ( e -o:z: - e -o(L-x)) -_
zOJtree -oL/2 COS h [ct (L/2 -
X
)]
(12.10)
/
Reference [12.23] contains a table showing similar equations for 11 other examples of track termination at the substation and load location. For practical applications, the effect of the leakance on the effective resistance of the track is of significance. This resistance value, which is also termed the equivalent track resistance RTeq, is defined in [12.23] as (12.11) As shown, for very large values of aL, the equivalent track resistance approaches the value of the surge impedance Z 0 . In practice, this already applies to substation-load distances of between 13 and 15 km if the leakance per unit length is 2 S/km. However, if the leakance is as low as 0,1 S/km, the corresponding distance reaches values of 65 to 70 km.
12.4.2.3
Track-earth circuit of AC systems
In direct-current traction systems, the current flowing to earth due to the track-toearth potential is distributed uniformly in the earth. The effective eart11 resistance is equal to zero in this case. In contrast, if the soil is assumed to be homogeneous below a single-phase AC railway line, the current density in the soil will decrea.se exponentially as a function of the depth. The penetration depth 6 defined by equation (10.20) enables the effective inductance and resistance of the earth in the track-to-earth circuit to be determined. The electromagnetic coupling of the current within an area close to the line causes the resistance of earth to achieve a value not equal to zero and proportional to the frequency, as described by equation (10.11). Figure 12.17 shows the the characteristic curve of the current density in homogeneous subsoil below a track. This model is based on reference [12.24] and has been discussed in
_______________
:::..::_:_:__ 644
________________ 12 Current return circuit and earthing
& a)
J
b)
_ _ _ _ _ _ _ __..jC-----=====--~·-d &
Figure 12.17: Graph of the current density J in the earth plotted as a function of the distance d from the overhead contact line. 8 = penetration depth
ss ltrc substation
traction vehicle
!JTE ,___ _ _ _ _ _L_ _ _ _ _ ______,
section of constant current distribution --"""''---+--.::,,..J'-----------1-e:c..__-4_ __.::,.._ _ x
Ltrans
1,0
t
-5
ltrc--
0,8 +-----+------+-----+-----+--/---+----t-------1
-fr
-
-x
Figure 12.18: Track-to-earth voltages (a) and currents (b) of a single-phase AC railway with single-ended feed to the traction vehicle by one substation.
greater depth in [12.25]. However, as the earth is composed of many layers of differing properties and thickness, the conclusions drawn from this model merely provide a basis for estimating the order of magnitude of the penetration depth. The studies described in [12.26] have demonstrated, by calculations and measurement, that voltages of approximately 50 V are induced in existing conductor loops located in a mine tunnel 400 m below and nearly parallel to a 50 Hz single-phase AC railway line. The longitud·inal pro.file of the currents in a single-phase AC railway is shown in Figure 12.18. Here too, single side feeding and a load at a distance L from the feeding point is assumed in order to obtain a simplified model. If the track on both sides of the load exceeds 3 to 7 km, wl1ich is a normal situation, t.lw curves shown are applicable for the
12.4 Earth as a conductor
645
Table 12.3: Earth resistances RE of substation earthing systems and portions JEA of the return currents flowing to the substation via the earthing system, in relation to the total traction current. Substation Dresden-Stetzsch Riesa Chemnitz GoBnitz
Substation locations
RE n
along double-track line large railway station area along double-track line large railway station area
0,12 0,23 0,07 0,10
[EA/ 11,c
% 21 9
51 15
currents flowing in the track and in earth and for the transition of currents between track and earth. The following basic statements and conclusions can be drawn from Figure 12.18: The traction current Itrc flows to the track at the location of the traction vehicle. The major part of this current flows towards the substation via the track. The remainder flows through the track in the opposite direction, i.e. to the right-hand side of the load in Figure 12.18. Currents flow from the rails to earth on both sides of the load location. This section in which the rail-to-earth currents are observed is called the transition section with the transition length Ltrans· In the section close to the substation, a portion of the return current in the earth flows back into the track, whereby a certain fraction of the earth current flows back to the substation through the associated earthing system. The magnitude of this fraction depends mainly on the earth resistance of the substation foundations. Table 12.3 contains guide values for earth resistance of substation earth electrodes and the associated earth currents. A track-to-earth voltage occurs within the transition ranges near the substation and near the load location. In EN 50 122 this is called the rail potential. As explained by Figure 10.3, inductive coupling of two conductive loops is effective in the case of earth return current of AC traction systems. The current flowing through earth is determined mainly by the inductive coupling between the conductive loops and only to a minor extent by the galvanic coupling, a function of the leakance per unit length. As a result of the inductive coupling, there will be a region of constant c'urrent distribution in the section where the tra;1sition processes have already decayed. In this section, no return currents will flow from rails to earth or vice versa. The irnpedances per unit length which were calculated according to 10.1.1.3, apply to this region. Applying the model used in [12.27] and assuming an infinitely long (i.e. longer than 5 km) electric railway line, according to Figure 12.18, the current flowing through earth to the left of the feed point and to the right-hand side of the traction vehicle location is (12.12) Equation ( 12.12) describes the earth current, comprising two components: the first is a constant component observed in the section of balanced current distribution and the
12 Current return circuit and earthing
646
second is a variable component describing the transition current which is a function of the distance from the relative points. Correspondingly, the rail potential or trnck-to-earth voltage is
U , = -trc I (1 - -k) (e-:r(L-x) - e-P) -0 Z /2
-TE
(12.13)
,
whereby Is_ is the coupling factor, 1 is the die propagation constant or coefficient of the track-earth circuit and Z 0 is the surge impedance of the track-earth circuit. These quantities are determined by the following relationships: (12.14)
k. = Zi
where Zi
k= Rk + j µf ln(8/a) Rk+Rfr+jµfln(8/req)
(12.15)
The propagation constant is
1=
Jz~E ·Y+E =
CY
+ j tI
(12.16)
because the leakance per unit length of track can be assumed to be a purely ohmic property, CY being the attenuation constant and ;3 the phase constant. Lastly, the surge impedance of the track-earth circuit is (12.17) The transition length Ltrans is defined as the distance over which the transition processes and values have decayed to approximately 5 % of their maximum value. This is the case for e-aLtrans :S 0,05 or CYLtrans - ln(0,05) ~ 3,0. Therefore
Lt rans = 3/ CY
(12.18)
Example: How do different leakance values affect the earth currents and the rail potential of a double-track railway line? The following parameters apply to the line: overhead contact line design Re 200 of DB, rails UIC 60, assumed leakances per unit length of the double-track line 0,5; l; 2; 4 and 8 S/km, frequency 50 Hz. According to (12.15), if values taken from the example in clause 10.1.1.3 and a mean earth resistivity of 290 Om, corresponding to 15 ~ 1530 m are used, k -
=
0,0164 + j 10-:3 · 0,4 · rr · 50,0 · 111(1530/6,5) 0,030 + 0,0164 + j 10-:3 · 0,4 · ,r. 50,0 · ln(l 530/0,0053)
0,0164 + j 0,343 0,046 + j 0,790
12.4 Earth a.s a conductor
647
Table 12.4: Transition length and track-to-earth potential depending on the leakance per unit length. Phase Surge impeLeakance Transition Track-to-earth constant 1 dance Z 0 Y. fE length Ltrans potential UTE n km 1/km S/km V/kA 0,110 + j 0,090 0,425 + j 0,360 27,0 0,5 150 1,0 0,213 + j 0,180 0,213 + j 0,180 14,0 75 2,0 0,425 + j 0,360 0,110 + j 0,090 7,0 38 4,0 0,851 + j 0,720 0,053 + j 0,045 3,5 19 1,702 + j 1,440 0,027 + j 0,023 8,0 1,8 10 The calculated approximate absolute values of k are k = 0,43 for l?E = 290 nm and k 0,38 for l?E = 27 nm. From this, it can be concluded that the earth current in the region of balanced current distribution is only minimally affected by the earth resistivity. The self-impedance per unit length of the track-to-earth circuit, as seen in the denominator of the above equation, is equal to Z~E
=
(0,046
+ j 0,790)
n/km
By inserting these results in equations (12.16) and (12.17) and applying Moivre's rule, the results given in Table 12.4 are obtained.
12.4.3
Earth electrodes in the vicinity of railways
12.4.3.1
Earth resistance of electrodes and pole earthing
An earth electrode is a bare conductor or other conductive component which is in electrically conductive contact with the earth, or a bare conductor or other conductive component embedded in a concrete structure which, in turn, has a large contact area with the earth. Earth electrodes in a railway installation may include: contact line catenary system support foundations, earthing strips installed parallel to the track and natural earth contacts, such as metal pipes, cable sheaths, parts of steel structures, foundations of buildings and substation earthing systems. Earth electrodes installed in the vicinity of railways and connected to the track increase the lealmnce per unit length between the track and earth. Earth electrodes are characterized by an earth resistance defined as the effective resistance between the earth electrode and the reference or remote earth. Figure 12.19 shows the earthing and potential voltages in a section perpendicular to the track of an electric railway. The earth resistance depends on the soil resistivity {2E, on the geometrical dimensions of the electrode and on its arrangement. The earthing strips installed along sections of electric railway lines are surface earth electrodes normally buried at a depth of 1 m. The earth resistance of an earthing strip of diameter b and length L 8 is given by the equation
Rn= er;:/(1rLr,;) ln(4Lr,;/b)
(12.19)
12 Current return circuit and earthing
648
-r--
1,0 0,9
TE
0,8 0,7 0,6
1
0,5 0,4
Jj_ UTE 0,3-
0,2 0, 1
I I TE --i- Uab IUGE -l-_____:_-r'=-----+---=~ ...._ ...._
0 --t---1'----'----'lc+--'-----t----+--------l I 15 10 15 20 I I a 1m
a4,5m
+50
m
100
Distance from track center a - - - -
Figure 12.19: Guideline values for the characteristic curves of the voltage UpE between a point P and earth reference potential and of the voltage [hp between the track and a point P on the earth's surface, all with reference to the track-to-earth voltage UTE at right angles to the rails and with l>E ~ 100 Dm. Examples of practical relevance for accessible voltages
at a1m: the accessible voltage fraction of the track-to-earth potential between the rail and a point on the earth's surface at a distance of 1 m from the rail. at a4, 5 m: the accessible voltage outside the overhead contact line zone, between a point on the earth's surface at a distance of 4,5 m from the rail and a metal object at reference earth potential.
Example:
What is the earth resistance of an earthing strip of galvanized steel, assuming this to be of 1 km length and 30 mm diameter at earth resistivities of 27 Dm and 290 Dm respectively? For l>E = 27 Dm, the earth resistance of this 1 km long earthing strip is approximately RB= 27 /(7r · 1000) - ln(4 · 1000/0,03) = 0,1 n. For l>E = 290 Dm, it is 1,06 n.
Earth rods are earth electrodes which are buried or driven deeper than surface earth electrodes. Overhead contact line pole foundations can be considered as earth rods. As explained in clause 7.7, poles are frequently set up on steel piles or pipes that have been driven into the ground to a depth of several metres. The earth resistances of the pole foundations form an important part of traction earth systems. They are also called pole earthing. To calculate the expected earth resistance Rrvr of a pole foundation it is treated as an earth rod. This permits the use of the following equation for calculating the earth resistance Rrvr for a pole foundation of depth t 8 and diameter d: PE l 4 tE RM = - - n - 2 rrtg d
(12.20)
For foundations with a rectangular cross section, a good approximation is obtained by substituting the diameter by the shorter edge of the rectangle. As indicated, in addition to the foundation geometry, it is the soil resistivity, above all, which has a. decisive effect on R'r.I· Poles set in in-situ cast concrete may have values
12.4 Earth as a conductor
649
Table 12.5: Guideline values of earth resistance and conductance of earth electrodes in railway applications for PE ~ 100 nm. Type of pole, type of natural earthing RM YM n s Concrete pole with concrete foundation 0,02 50 Steel pole on in-situ concrete foundation 40 0,025 Pole with conductive connection to steel pile 14,3 0,07 Earthing strip electrodes, double-track line, per km 0,167 6,00 Lighting pole 50 to 100 0,01 to 0,02 Bridge railings 30 to 60 0,03 to 0,07 Roof drain with drainpipe 125 0,008 Water supply pipeline network, buried 2 rn deep, pipes of between 1,5 inch and 150 mm nominal diameter 1 l 0,2 to 0,4 2,5 to 5 Water pipelines, 3 km long, nominal diameter 150 1 ) 2,3 0,43 1) according to reference [10.25] Table 12.6: Pole earth resistances R-M of steelreinforced concrete foundations in soils with different earth resistivities. Values given in n.
Volume 3 m 1 2 3
Soil resistivity l!E in nm 290 27 100 20,3 58,9 5,6 16,1 46,7 4,3 14,1 40,9 3,8
of several hundred ohms in dry locations because the high resistivity of concrete (cf. Table 2.13). In comparison, pole foundations on steel piles driven into the ground have earth resistances between 8 and 15 n. Similar low values are found for driven steel pipes. Earth resistances of 2 to 13 n have been measured on driven steel pipes with an external diameter of 508 mm. The length of such pipes commonly varies between 3,5 and 6,0 m. Table 12.5 shows guideline values of pole earth resistances commonly occurring in the DB area. This table is based on the DB directive 997 [12.9]. Example:
What is the earth resistance of a pipe of diameter 0,508 m driven into the earth to a depth of 5 m, assuming the earth resistivity to be 27 and 290 nm? The respective values are found to be 3,2 and 33,9 n.
According to EN 50 341-1 and DB directive 997 [12.9], the following equation can be used to calculate the earth resistance of concrete foundations with steel reinforcement RM
=
(]E/ ( rrd)
(12.21)
In this equation, d is the diameter of a hemisphere with a volume equa.l to the volume V of the foundation: d - 1,57 vi/a. Example: What are the earth resistances of steel-reinforced concrete foundations of various volumes at various locations, assuming the earth resistivity f!E to be 27: 100 and 290 nm? The Table 12.6 shows the results for foundations of volume 1; 2 and 3 m:3. This example shows that the pole earth resistance is essentially determined by the soil resistivity. The foundation volume has lit.ti<~ effect.
12 Current return circuit and earthing
650
Table 12. 7: Effective leakance per unit length for different pole earth resistances, assuming 16 poles per kilometre, all values given in S/km. Design of permanent way
Concrete slab track Ballast, one rail insulated Ballast, two rails insulated Ballast witout insulation of rails
'Irack leakance S/km 0,01
0,05 0,10 1,00
10
n
1,61 1,65 1,70 2,60
Effective leakance Pole earth resistance 20 n 50 n 100 n 200D 0,81 0,85 0,90 1,80
0,33 0,37 0,42 1,32
0,17 0,21 0,27 1,16
0,09 0,13 0,18 1,08
500
n
0,042 0,082 0,132 1,032
It should be noted that equation (12.21) applies to concrete foundations with steel reinforcement. In sandy soils without ground water contact, the earth resistance of in-situ concrete foundations without reinforcements may reach values as high as 300 n.
12.4.3.2
Effective leakance per unit length
The poles, the foundations of which each have an earth resistance RM, are earth electrodes connected parallel to the track. These parallel earth electrodes represent a significant contribution to the effective leakance per unit length YfEeff· The effect of the pole earth resistances on the effective leakance per unit length of a track has been calculated for typical assumed track leakance values and various types of track superstructure. A RM value range of 10 to 500 n, which is realistic in practical cases, was chosen. The calculation was carried out for a line with 16 poles per kilometre being connected electrically to the track. The results are shown in Table 12.7. In double-track lines, the potential sinks of the rail-to-earth voltage overlap when two trains meet. As a consequence of that the rail potential doubles. In the vicinity of stations and buildings or non-railway metal structures, standard EN 50122-1 demands that, for AC traction systems, all conductive parts, e.g. handrails of bridges, signal masts etc. be directly connected to the rails, i.e. to traction earth. This additional traction earthing leads to the effective leakance per unit length in such areas being higher than the ones calculated above. In stations, the effective leakance per unit length is further increased by other tracks running parallel to the main track. For example, in a railway station with four tracks with ballast permanent way and two rails insulated according to Table 12.4, the total effective leakance per unit length is 2 · 0,42 S/km + 2 · 0,10 S/km = 1,04 S/km, if the pole earth resistance is 50 n. Because of this effect, effective leakances per unit length of 10 S/km and higher can be observed in large stations with many tracks parallel and many components bonded to traction earth.
12.5
Direct-current traction systems
12.5.1
Design of the return circuit and earthing installations
Safety provisions and protective 1neasures against stray currents significantly determine the design of the traction return circuit and the ear·thing installations of DC supplied
12:_5 Direct-current. t.rac:tionsyst.erns________________
\
651
'
+'c +++stray current
--
--
---
/
+;J-4 + + structure earth /
Figure 12.20: Return circuit and earthing of DC railways. 1 high and medium voltage protective earthing 2 low-voltage protective earthing 3 earthing of telecommunications and signalling systems 4 lightning protection earthing +++ possible stray current corrosion areas 6 insulated arrangement of rails
railways. Based on the information given in 12.2 and 12.3, this clause deals with system configurations and their planning and implementation, with strict separation between the return circuit and structure earth, complying with the stipulations of Railway Standards EN 50122-1 [12.1] and EN 50122-2 [12.13]. These concepts have proven their qualification for high-capacity mass transit railways as demonstrated by examples. The power supply for DC railways includes the three-phase AC feeding network on the medium- or high-voltage side, the traction power supply system and the auxiliary low-voltage supply of technical equipment and buildings. Various configurations for the traction return circuit and earthing and bonding exist and are also suggested for new installations. They cover requirements both for safety of people [12.1, 12.10, 12.11, 12.28] and also for protection against the effects of stray currents [12.2, 12.13, 12.14, 12.15, 12.29, 12.30]. In addition, they must also ensure protection of electrical equipment and lightning protection [12.31, 12.32, 12.33]. \Yhere provisions for safety of people conflict with stray current protection, then safety must be given highest priority. Practical applications require coherent solutions that can be implemented into the overall configuration in a simple and economic manner. The European standards EN 50 122-1 and EN 50 122-2 regulate the addressed set of problems and contain stipulations for structures, three-phase high-voltage power supply, DC traction power supply, signalling and telecornmunications equipment and low-voltage supply in buildings. The standards form the bas;s for the systern confi,guratwn described below. Figure 12.20 illustrates the main elements of Lhe Teturn circuit and earthing and bonding using the example of a tunnel system. The return cunents flow through the running rails and insulated retnrn cables to the foecling rectifier_ Running rails and return cables, tlwrdorc, form t!te return circuit. However, due rci \ arving track voltage along
12 Current return circuit and earthing
652
the line and practical values of insulation, currents from the running rails stray into the soil and can flow through metallic conductors in contact with soil. Stray current corrosion occurs at the position of current transition from metallic conductors to an electrolyte. Figure 12.20 shows the possible stray current corrosion areas for the case where a vehicle is fed only from one substation. The degree of metal erosion depends upon the current, the type of metal and the duration of exposure (see clause 12.5.3). The structure earth, also known as tunnel earth, in Figure 12.20 is not connected with the return circuit and serves as protective earth for all equipment components, such as the three-phase high-voltage and medium-voltage installations and also signalling and telecommunication installations.
12.5.2
Safety of persons
Both the touch voltage following faults in the three-phase feeding system and the potentials on running rails must not exceed the permitted values in accordance with
12.5 Direct-current traction systems __
653
principle that protective provisions against electric shock are to be given higher priority than provisions against stray current corrosion. The standards specify that the. resistance between the return conductors and conductive installations not insulated against earth must be as high as possible. Therefore, the supporting structures of overhead contact lines in contact with earth need to be connected to the return circuit, in practice to the running rails, via voltage fuses which will become active in case of a short circuit. This is not necessary for nominal voltage up to 1500 V and for doubled or reinforced insulation of the contact line system.
12.5.3
Stray current protection
12.5.3.1
General information on stray current corrosion
The rails are mounted on sleepers, which in turn are placed on ballast, the sub-ballast, an insulating layer and finally, the earth. A concrete slab permanent way is an alternative to sleepers and ballast. A high track-to-earth resistance is only found in cases where new track is laid with well-insulating ballast on exceedingly dry sandy soils. The same applies in the case of frost. In most cases however, the track-to-earth resistance is such that a part of the return current will flow through earth, whereby the soil acts like an electrolyte. For this reason, currents leaving the running rails can cause stray current corrosion on metal pipes and other underground installations in the vicinity of DC traction railways. Every metal object in an electrolyte is subject to an osmotic pressure and a solution pressure, which are normally in equilibrium. If this equilibrium is disturbed by an electric current, e.g. due to currents passing from the rails into earth, however, electrochemical corrosion takes place. In such cases, two parallel processes occur, as will be explained below, using iron as an example. These two concurrent processes are the anodic reaction Fe-+ Fe++ 2 e and the cathodic reaction 1/2 0 2 + H 2 0 + 2 e -> 2 OHat PH> 7, or at PH< 7. In the anodic reaction, an anodic current component Ia flows from the metal into the electrolyte. In the cathodic reaction, a cathodic current component lie flows from the electrolyte to the metal. When no external current is imposed, the following equilibrium equation applies to homogeneous metal surfaces in a homogeneous electrolyte: Ia
+ (- h)
It;ot
=
0
(12.22)
If this equilibrium is disturbed by an externally imposed current, two possible cases may occur: I1.ot
> 0 i.e. increase of tl1e anodic reaction, in which case there will be stray
current corrosion, and Itot < 0 i.e. increase of the cathodic reaction. This is the principle underlying ca/;/wclic protu:t-ion.
. ·1
I
12 Current return circuit and earthing
654 dx I
I
I T'F dx I
dlfr (x) =R'r IT (x) dx
t
U i(x)
Ur(x +dx) ~_R_'r_~,___---~x-'+dx fr(X+ dX)
I -----TE I (Ur (x)--UE )Yrcdx (JE
Figure 12.21: Potential dropalong a track element of length dx.
f
When stray current corrosion occurs, metal dissipates from the conductor into the earth at the point where the current leaves the conductor. The mass m of metal erosion can be calculated according to Faraday's .first law of electrolysis: t2
m
=Cf i(t) dt
(12.23)
t1
C is the electrochemical equivalent of the metal and i(t) is the current flowing in the
time interval between t 1 and t 2 . The metal masses, which would be eroded by a current of 1 A within one year, would be 9,1 kg iron, 33,4 kg lead and 10,4 kg copper. To be able to calculate the equipment dimensions so as to prevent this, it is necessary to know how high the proportion of the traction current flowing into earth is, as well as the resulting rail potential. ' On the basis of the equivalent circuit in Figure 12.21, the following can be deduced from the potential gradient along a track element with uniform electric load distribution:
dUT(x)/dx = IT(x) · ~
(12.24)
and from Kirchhoff's law of currents:
dh(x)/dx + I~= (uT(:r)
uE). y;E.
(12.25)
In this equation, I~ is the line load as defined in (10.37). By inserting the propagation constant a according to (12.6), the following equation result for the current flowing in the track:
IT(x) =A· exp[-a (l - x)]
+ B · exp[a (L - x)]
(12.26)
With this equation and the related boundary conditions that are the voltages and currents at the feed point and at the load point, it is obtained
I}· L . h(x) = . h( I)· smh[a (L - :r)] sm
a
(12.27)
1
By inserting the line load current flowing to earth:
n as defined
IE(x) = 1; · (L - :r) - h(.r)
m (10.36), an equation is obtained for the
12.5 Direct-current traction systems
655
--11,c line
!11,c
-Ir
rail
ttllll(III''' underground
- - corrosion area - - -
(
()
-Ip
metal installation
Figure 12.22: Stray current corrosion, line having positive polarity.
L - x _ sinh[a (L - x)]) L sinh(aL)
(12.28)
For comparison, the current resulting from a single load at one point in a feed section is
(L/2 - x)]) 1E (x·) _- 1trc ( 1 _ co_sh[a cosh(a L/2)
(12.29)
Furthermore, the rail potential of a line, assuming a uniformly distributed load along the line, is given by:
U TE
U ( ) _ U = Itrc · L ( _ ,L cosh [a (L x)] ) T x E Y,:' 1 a . h( a L) TE sm
(12.30)
For a single load at one point in a feed section, the potential is
Un., = J
a . sinh[a(L/2 - x)] t}E cosh(aL/2)
ftrc·
(12.31)
The latter equation corresponds to (12.9). For practical applications, it is important to distinguish between areas liable to stray current corrosion and areas in which there is no such danger. As shown in Figure 12.22, the boundary between the area where current flows out of the track and where current flows from earth back into the track is at the point Xgr· This point is also the boundary between sections with positive and with negative rail potentials. This is also the point at which the largest stray current will occur within the section under consideration. By inserting x O in equation (12.30) it is obtained UTE -
ftrc · L ' n · 1 TE
[1 - aL coth(aL) ]
The term aL coth( 0:L) is always greater than 1, i.e. UrE is negative if the contact wire polarity is positive. The boundary between the anodic area and the cathodic area is termed the boundary distance :i;g1 • At this point Unc, = 0 and equation (12.30) is then transformed to sinh(oL) - o,L · cosh [n'.(L
:rg 1 )]
12 Current return circuit and earthing
656
k½7J2T/2½1///!!,c//1/T/2V~ ~~~:~~~ line f
f
t I t
LSI
f
f
t t • t -
f
t
f rails negative
f
t ' t
t
lp
pipeline
area in which corrosion may occur
s u
/
/
/
~
f2Z2277J?1/J?1//?f,;zT/2V20J
6
t
t
t t t t
t t t I , t t t I
f
~~~~~~ine
t rails positive
t
t t t t
Ip-
pipeline
area in which corrosion may occur
u
-- -- --For
O:'
-t 0, the boundary distance Xgr
~L
(l
Xgr
J3/3) = 0,42 · L
Figure 12.23: Effect of the polarity on the location of the area in which corrosion may occur. SS = substation
is (12.32)
In real applications, however, the total load on a traction system comprises discrete, moving individual loads because of trains moving along the lines. As a result, the boundary between the anodic and the cathodic areas will be located in a region in the vicinity of Xgr· 12.5.3.2
Effect of the polarity
The polarity of the track and the contact line will affect the position and size of the area in which stray current corrosion may occur. The historical de\·elopment of currentconverter technology and the associated substation switchgear design necessitated by this has led to negative potentials being used for the contact lines of some mine railways and of the Berlin metropolitan railway. Normally, the contact lines of trams and other metropolitan railways are at positive polarities. Figure 12.23 shows the track-to-earth voltages Urn and the voltages UPE between metal
12.5 Direct-current traction systems
657
underground installations and earth for both positive and negative contact lines, assuming a continuous, distributed load along the respective stretch of track. According to (12.30), the cathodic area of the underground metal installation is at the far end of the line and, according to (12.32), it is of the length 0,58 · l. This situation is described as diffuse stray current corrosion. If the contact line is positive, the area in which corrosion is likely to occur is at the substation end. In this case, tfie effect is termed concentrated stray current corrosion. According to -[12.30], the intensity of corrosion of underground metal installations near railways with positive contact lines and without protective measures against stray current corrosion is at least twice as high as would occur in the vicinity of negative contact lines. For this reason, the conditions for installing active protective measures against stray current corrosion are more favourable with a positive contact lill'e polarity. 12.5.3.3
Protective measures against stray current corrosion
The objective of protective provisions against the effects of stray currents is to avoid the danger of corrosion on third-party and railway-owned installations. It is necessary, on one hand, to limit the stray currents and on the other hand, to identify and correct faults in the return circuit in time [12.13, 12.14, 12.15, 12.16, 12.17], to avoid a reduction of the installation service life. A low longitudinal voltage drop in the return circuit and good insulation of the ~ t earth a~~ the most sig1!ifi~-int.f.:1ctorsj11 lirnitiJlg tlu\~tJ9,y·_·· -·········-------cc········· the-rongffi.idinal voltage drop d~Qends upon the distance between substations and the resisfance-of th~ r~turn. circuih.§_tJ:flY~lSO i~fluenc~;-t·h~ re<.J~;i~ed···· number of substations and, as consequence project c;~~---------···-·-····-·--·-···---~---·--
C~~~eilLP!;~~ti;I;·
aie
The prntectTve measures againsCstiiy.cui:ients necessary to protect third party installations, railway-owned steel-reinforced tunnel and viaduct structures and steel reinforced track bed or similar rail fastening techniques for at grade sections. A distinction should be drawn between passive and active protective measures. Passive protection involves coating the relevant metal installations with an insulating material or a corrosion-resistant metal. Active protective measures involve measures implemented in the railway traction energy supply systems, such as reducing the distance between substations, reducing the length of the track return system by moving the track return connection away from the substation, reducing the leakance per unit length between running rails and Parth, reducing the resistance per unit length of the current return system, and installing parallel reinforcing return lines, i.e. conductors running parallel to the track and connected with the rails at short intervals. Active protective measures also include a variety of implementations of cathodic protection. As described in detail in the preceding sections, the cathodic protection principle is based on preventing anodic reactions on the metal to be protected. Figure 12.24 shows several cathodic protection methods. The restricted use of drainage methods is explained in [12.13] as follows:
i I
I 12 Current return circuit and earthing
658
Figure 12.24: Active protective measures against stray current corrosion. a) direct stray current diversion b) directional stray current diversion c) forced stray current drain
pipeline
return circuit
tunnel structure earth
earth
Figure 12.25: Electrical equivalent circuit diagram for a DC railway system in a steelreinforced concrete tunnel.
The connetion of any structure e.g. to the negative busbar in a substation even in a polarised electric drainage device will increase the overall stray current. Therefore, the connection of any conductive structure to the return circuit should be made only due consideration given to the overall effect on the other structures which may be affected. Further discussions of the associated issues are found in standards EN 50 162 [12.29) and 50122-2. (;, er,\ y(J) J ?_,?_ - 1The criterion of 100 m V [12.13], which is also applied for the assessment of cathodic protection, has proved to be an effective method for the assessment of the stray current impact which can also be checked in a simple way. This criterion indicates that there is no danger of corrosion for steel-reinforced structures or other metallic conductors laid in contact with earth, if the average value of the potential change per hour, during periods of highest traffic, does not exceed + 100 m V . Figure 12.25 shows an electrical circuit diagram to calculate a DC railway system in a tunnel. The maximum longitudinal voltage Us occurring between any two points in the structure depends upon the following parameters [12.13, 12.14, 12.15): length of a supply section, resistance of the tracks, resistance of the tunnel structure, conductance per unit length G!1, 8 between the return circuit and the tunnel structure, conductance per unit length G(m between the tunnel structure and earth,
12.5 Direct-current traction systems
659
return circuit
01
------ --
--------
.Figure 12.26: Stray current collecting net and stray current drainage in DC railway systems.
maximum 1-hour average value of the traction current with the indices T for Track, S for tunnel Structure and E for Earth. VDV 501, Part 3 [12.15] refers to a computer program that calculates the rail potential and the longitudinal structure voltages using the above specified parameters. The conductance per unit length G~E between tunnel structure and earth is set to zero in this program. More advanced computer programs for stray current calculations model all possible conductance per unit length between individual conductors, e.g. between the structure and a pipeline, between a pipeline and earth or between the structure and earth, using a multiple conductor model with distributed parameters. This allows the calculation of stray currents in structures, pipelines and in the earth and is the basis for achieving a technically optimised solution.
12.5.4
Stray current collecting nets
The system design according to EN 50122-2 [12.13] is based on insulated running rails and continuity of the earthing installations for protective earthing and protection against stray currents. Concepts however, also exist that suggest polarized drainage or stray current collecting nets for tunnel and viaduct structures and for systems with steel-reinforced fixed track, to protect against stray current corrosion. The stray current drainage via diode Dl in Figure 12.26 forms a metallic unilateral connection between the tunnel and running rails and avoids corrosion in this area. At the same time, this connection reduces the resistance of the stray current path between the running rails and structure increasing the overall amount of stray currents. The DC currents flowing through such drainage installations evidently show this unintentional effect. In a further alternative, additional reinforcement rods in the concrete layer under the running rails form a stray current collecting net which is connected to the running rails with the stray current drainage diode 02. In reality, the stray current bus system cannot be insulated frorn the structure satisfactorily, or only with imr;;~-~~~;-;f{ort. Rarely ~in errors design be corrected. The cmrent densities increase at these error locations, so that the stray current drainage D2 increases the danger of stray current corrosion on the structure in this case. A stray current collecting net may be employed without stray current, drainage. This separate stray current collecting net principally reduces the stray currents. However, no defined potential can be associated to the stray drainage collecting net, so that induced
12 Current return circuit and earthing
660
voltages could also interfere with the track release systems. Furthermore, protective tripping must be ensured during a short-circuit between the contact wire and the stray current collecting system to guarantee safety. Extensive comparative calculations were performed for the effects of stray current collecting nets for the European Standard EN 50 122-2 [12.13], which demonstrated that stray current drainage increases the rail potentials by a factor of up to two and the stray currents by a factor of four. Measurements in a tunnel system confirmed the theoretical investigation [12.34]. The construction and commissioning of the BTS Mass Transit System in Bangkok was Siemens leadership [12.35]. Stray currents for different designs were calculated for the BTS system built as a viaduct with a DC 750 V third rail. The concept with through connected structure reinforcement was compared with a design adopting such a stray current bus net with drainage diodes. The stray current drainage increased stray currents through the structure reinforcement by a factor of 10. The results of the investigations illustrate the technical problems involved and additional investment required for stray current collecting nets using drainage methods. The drainage diode cannot be recommended for stray current countermeasures.
12.5.5
Design of DC installations with respect to return circuit and earthing
12.5.5.1
Basic recommendations
The design of the return circuit and of the earthing installations must satisfy both .safety and .stray current protection measures. Figure 12.27 shows provisions that satisfy these requirements in an overall circuit diagram. The running raiJ.~g~termine the longitudin 91Li:esistanc.e....aL.the return circuit. To achieve as lowa-volt~ge drop3}§ p9ssi.ble, we1cte
---
!~-5 _Direct-current traction systems
661
substation
station return circuit
signal
AC switch gear
station power supply
8 ~ shielded cables
structure earth
feeding cable
I
I
railway-owned installations
------------------- ---------------------------------- ------------------------------\--third party installations pipes with insulation joint
Figure 12.27: Schematic diagram of the return circuit and r.elated measures for earthing and bonding for DC railway systems.
voltage limit is exceeded. To limit the rail potential and the stray currents to the stipulateg ~<1lues, the lor1gituilinaGesistance c~-~-be-r-educed by-larger cross sections of running rails or by lQ,ytgg an aclditional cable connected in parallel with the--~~~ing-~:~Iis-~ncCTr~;~1~te
Railway-owned earthing systems
Building foundations, tunnel structures and the foundations of elevated systems form the railway-owned earthing systeni of DC railways which generally is known as structure earth. The resistance to earth of the whole installation must be so low that the permissible touch voltage is not exceeded in case of earth faults in the three-phase supply system. Iu tunnel and viaduct installations, the electrically interconnected reinforcement along the line forms the structure earth for the installations, as shown in Figure 12.27. The si ugle-pole AC short-circuit rnrrents and the requirement for the limitation of the stray currents determine the miuimum required electrical cross section and also the longitudiual rnsistauce of the structure. It has proved ad·va.ntageous to lay earth cond:uctors in \
________ 12_ Current return circuit and earthing
662
parallel to the structure to which the structure segments can be connected, as shown in Figure 12.27. It is easy to install and this type of through-connection can be checked with respect to the criterion of 100 m V. There is no through-connected earthing system for at-grade lines. Stations, substations, technical buildings and even all contact line supports act as independent earthing systems. 12.5.5.3
Earthing measures for the three-phase power supply
A favourable way to achieve low values of the voltage to earth in case of single pole faults is to limit the single pole short-circuit current by using a star-point resistor at the feeding transformer of the three-phase power supply. The resistance and size of the respective star-point resistor depends on the resistance to earth of the installations. The resistance to earth of tunnel and viaduct systems usually is below 100 mn, so that the voltage to earth is likely to be low. For at-grade structures with foundations of minor size however, it can be necessary to add additional earth rods to comply with the permissible touch voltage. For stray current protection purposes the earthing installations of the public supply network should be separated from the DC railway earthing installations. However, this separation can only be achieved if the cable sheaths are not connected to the DC railway earthing installations. Since dangerous voltages can occur at the open end of the sheath, these sheath endings should be protected against touch contact and be labelled accordingly. The open cable sheaths must be connected to the railway-structure earth during work on the medium-voltage installation. In many cases, substations and stations of metro systems are supplied from railwayowned medium-voltage rings. The sheaths of the medium-voltage cables, the metal frames in the medium-voltage installations and the rectifier transformers must be connected to the structure earth. If the station supply is provided from the public low-voltage network, neither the neutral conductor N nor the protective earth conductor are allowed to transfer the potential outside the building [12.1]. In this case, the low-voltage protection must be ensured by other methods, e.g. residual-current circuit breakers. 12.5.5.4
Traction substations
Usually, the frames of the DC switchgear in tract'ion substations areinsulatecl against structure earth. Frame fault detection in the DC switchgear installations, e.g. rectifier and DC switchgear, is provided by a low resistance connection at one point, as shown in Figure 12.27. A current monitoring l> in the earth connection and an optional voltage monitor between the return circuit and the DC switchgear frame cause switch off the medium-voltage transformer if insulation faults or una('.ceptable touch v0ltages occur. To keep the running rail potentials as low as possible, the running rails should be sufficiently cross-bonded at the connection point of the return cables. The return cables to the rectifier substation must be insulat<~d frorn earth to avoid stray currents.
12.5 Direct-current traction systems
12.5.5.5
663
Line sections in the open
The German transportation companies association (Verband Deutscher Verkehrsunternehmen VDV), gives recommendations and examples of implemantations to railway operators in its publication 500 (12.14] on earthing measures for DC railway traction systems up to 1500 V. In this publication, the following recommendations are made with regard to DC traction current systems: Overhead contact wire supports need not be connected to traction earth, since overhead contact lines are equipped normally, with either reinforced or double insulation. The casings and bodies of equipment in contact with traction voltage are to be insulated from the foundations and/or against the supports. They must be directly earthed on the structure earthing systems. Indirect or open traction system earthing is also possible. If a point machine, which is not connected to traction earth, is operated via linkage mechanism within the reach of human beings, then the linkage mechanism must include insulation adequate to withstand the nominal traction voltage. Metal conductor rail supports do not have to be earthed if they are installed on insulating bases. The supporting framework of conductor rail switchgear is to be installed on insulated bases and connected with traction earth either directly or via the control windings of a current relay. Protection measures are to be taken in the overhead contact line area and pantograph area in accordance with [12.1] against persistent dangerous touch voltages at overhead contact line systems. In the event of broken contact wire or dewired pantograph, the over head contact line must be switched off automatically in case of contact with partially conductive structures, metallic components and electrical equipment. This is achieved by the direct traction system earthing or by open traction earthing. These protection measures also apply to contact line poles. The direct connection of the catenary poles to the running rails does not apply to DC railway systems with nominal voltages up to 1,5 kV, if double or reinforced insulation is used [12.1]. For nominal voltages higher than DC 1,5 kV, the contact line poles must always be connected to the return circuit preferable via voltage limiting fuses. To avoid connecting every pole individually to the return circuit, they can be interconnected with an earth wire and then connected to the running rails via a common voltage-limiting device. The earth wire should be subdivided into sections of a suitable length to reduce the danger of stray current corrosion at the pole foundation. To avoid mechanical damage to the contact line poles by lightning strokes, it is recommended that the reinforcement of the pole foundations is connected to the reinforcement of concrete poles or to the steel poles. No protection measures are necessary [12.1] for small accessible conductive parts not containing electrical equipment.
664
12.5.5.6
12 Current return circuit and earthing
Passenger stations
During multiple starting of trains, and especially during the through connection of feeding sections in the case of a substation outage, the rail potential may reach the maximum permissible touch voltage. To minimise risks to safety of persons, voltage monitoring devices with a short-circuiting function, referred to below as short-circuiting devices, are employed especially in stations with heavy duty suburban, regional and metro traffic. These devices register the voltage between the return circuit and the structure earth and connect both for a short period of time if the rail potential reaches excessively high values. The connection is automatically reopened after approximately 10 s. The tripping of the short-circuiting devices should be registered or signalled to a control centre for monitoring and indication of unusually frequent switching operations prompting investigation of the cause. 12.5.5.7
Signalling and telecommunications installations
Since electrically conductive connections between running rails and structure earth or earth are not permitted, signalling installations, track release installations, point machines and other installations, imperatively connected to the running rails, must be insulated against the structure earth and earth to avoid stray currents. To use the reduction effect, the sheaths of railway-owned telecommunication and signalling cables can be connected on both sides to the structure earth in stations and along the line. 12.5.5.8
Depot and workshop area
Voltage differences between the structure earth and the return circuit can be a hazard for staff and equipment during work on the vehicles. To avoid this danger, the return circuit and the structure earth in the depots and workshop areas shall be interconnected (12.13]. Damage to electrical tools can be avoided in the same manner, if the running rails and the protective earth conductors of the tools are at the same potential. Additionally electric shock in the course of rolling stock maintenance and service work is avoided. The conditions under which direct connections of this kind are permissible are: separated feeds, - isolation from the main track by means of insulated rail joints, and - insulated feed-through of all cable sheaths and pipelines. The depot is supplied by a separate traction power supply rectifier to limit the stray currents when the return circuit and the earthing installations in the depot are interconnected. The running rails and the earthing installations of the depot are separated from the line. Short feeding sections and low operating currents support the same intention. In [12.36], an investigation was carried out to determine how stray currents are affected by connecting the running rails in a depot with the structure earth. The depot under
12.5 Direct-current traction systems
665
250m I-c-------"-'-'------350m 1---=-==---~ o o E u·u
.a.a~ ~ 5
depot entry
C
u8
end of depot
Figure 12.28: Return conductor arrangement in a depot area.
building (structure) earth electrode system
0,3
% case II
c
~
'5 0,1 ()
~
t5
100
-0,1
200
-0,2 vehicle
return conductor connection
depot end
Figure 12.29: Stray currents in a depot when the rails and the building earth system are separated (case I) and when they are connected (case II).
study had a separate feed and the rails were isolated from the main track by means of insulated rail joints. Figure 12.28 shows the situation in the respective depot. The depot parameters are 10 tracks, a track resistance per unit length of 22 mD/km, track leakance per unit length of 0,5 S/km, building earth electrode resistance RE 0,33 n and a return conductor resistance of 1,5 mn. Assuming that a traction vehicle is drawing a current at the entry of the depot, the stray currents were calculated as shown in Figure 12.29. The average current, as observed over a longer period, must be taken as a basis for evaluating the corrosive effect of stray currents. In the case in question, the advantages of having tracks and structure earth at the same potential during repair and maintenance work outweigh the disadvantages resulting from the higher stray currents. If we apply the 0,1 V criterion of 100 m V described in clause 12.5.5.9 is applied, the limitations of such separate feeds and complete interconnection of all parts likely to assume a higher potential within a depot area soon become apparent [12.37]. The heating energy consumed by carriages parked in the depot leads to a fairly high current being drawn for lengthy periods, increasing the danger of stray current corrosion. A survey carried out on 22 public transport operators in Germany showed that 15 had chosen this form of separate feed and interconnection of the structure and traction earth for existing, projected or planned workshop or depot installations [12.38].
12 Current return circuit and earthing
666
The return circuit and the structure earth should be connected in the centre of the depot tracks only at one point, to keep the longitudinal rail voltages in the depot as low as possible. Further connections to wheel lathes, vehicle lifting devices and crane systems often cannot be avoided during working. It is advantageous to install these tools close to the central connection of the depot tracks and the structure earth. 12.5.5.9
Tunnels
Stray currents can flow into reinforced concrete tunnels. In tunnels of this kind, the electrical bonding of conductive metal reinforcement and all other metal parts is required as a prov1s10n to provide protection against indirect contact, - to provide protection against the hazards of the rail potential, and - to reduce hazards associated with stray currents. In this respect, EN 50122-2 [12.13] specifies that the calculated maximum longitudinal voltage between any two points of the entire tunnel construction must be < 0,1 V. The longitudinal voltage gradient is calculated using a modified form of equation (12.9). Using the track resistance per unit length Er which can be taken from Table 10.6, the longitudinal voltage drop in the tunnel assessed by a worst-case study according to [12.13], Annex C.
Us
=05·I '
R's- · [1 - -Le . ( 1 - e -(L/L c ))] · L · -Rfr - ·(Rfr + R's) L
(12.33)
where:
Le = 1/ j (R!r + R's) · G~s
(12.34)
and
Us is the longitudinal voltage in reinforced railway structure, in Volts G~s is the conductance per unit length, in Siemens per kilometre I
L
Le
R1r R's
is the average value of the traction return current of the considered section in the hour of the highest load, in Amperes is the length of the considered line section, in kilometres is the characteristic length of the system running rails/structure, in kilometres is the resistance of the track per unit length, in Ohms per kilometre is the resistance of the interconnected structure per unit length, in Ohms per kilometre
The calculation method in equation [12.35] is very conservative. The formula assumes an infinitely long tunnel on each site of the considered section. Furthermore, it doesn't take into account the reducing effects of the train movement in adjacent sections and the conductance per unit length of the tunnel structure against earth. The calculated values can be much higher than in reality.
12.5 Direct-current traction systems
667
·-·--------··--·---··-···--·--·--------.:_:_
Calculate the voltage Us for a double-track section of railway line of length L = 1 km, the entire length being situated in a tunnel. The hourly mean value of the traction current is 900 A. The other required parameters are: R1r = 0,09 D/km (according to Table 10.6), Yfs = 0,04 S/km (superstructure with one rail per track insulated, after long period of use), R's = 0,05 D/km (8 x 400 mm 2 steel). The characteristic length is determined as Le 20,58 km. Using this value, the voltage to be determined is calculated as Us 0,096 V, which is just within the required limit of Us::; 0,1 V. . As clearly seen from this example, the tunnel voltage would easily exceed the value of 0,1 V if the leakance per unit length were to increase. In this case, additional measures would be needed to combat stray current corrosion. Installation of supplementary parallel return conductors would be an alternative.
Example:
Other requirements for the design of electrical installations in tunnels are: Metallic, conductive connections between the running rails and the tunnel reinforcement or other steel components must be prevented. Metal pipes which lead into the tunnels must be insulated electrically from the sections of pipe outside of the tunnel. Cable sheaths and armouring must also be insulated by insulating joints where they lead into tunnels. Cable sheaths, armouring and metal pipelines are not allowed to be electrically connected with the structure (tunnel) earth. Where normally-open short-circuiting devices are installed as protective provisions against intolerable high voltages between metal parts of the tunnel structure and the running rails carrying the return current, they must meet the following specifications: The short-circuiting device should automatically drop back into its idle state 10 seconds after it has been triggered, or, if the device does not return to its idle state, methods must be implemented for documenting the cause of the fault, which must be remedied immediately. The installation of parallel return current conductors is recommended as an effective way of limiting track-to-earth voltages and minimizing the hazards due to stray currents, simultaneously achieving favourable conditions for implementing protection against electric shock. Computer simulation calculations were used to determine the track-to-earth voltages and stray currents at the current location of a traction vehicle. The vehicle was on a double-track DC 750 V traction railway line with a heavy traffic load. Headway between trains was 5 minutes, traction and braking power consumption was up to 4000 kW per train and track-to-earth leakance values were 0,02 to 2 S/km. The highest track-to-earth voltage, Una; 210 V, was found for YfE = 0,02 S/km. An increase of the leakance per unit length to 2 S/km led to a reduction of this voltage to 140 V. At the same time, the stray currents increased by a factor of 50. The solution found for this problem, meeting both the demand for a reduction of the track-to-earth voltage and of the stray currents, ,vas to install a 1000 mm 2 cross section copper return conductor parctllel to the running rails. On a new pennanent way, with one rail
12 Current return circuit and earthing
668 Feeding point
Single load
Gap
Overhead contact line Substation
Lightning arrester
Return circuit
Figure 12.30: Lightning protection measures in DC railway systems.
insulated with a leakance per unit length of 0,02 S/km according to Table 10.13, this supplementary return conductor reduced the maximum track-to-earth voltage from 210 V to 120 V and lowered the stray currents. These were already very low, by more than 60 %. The model for computer simulation was presented in [12.39]. 12.5.5.10
Lightning protection
Lightning strikes or flashover cannot be avoided on at-grade lines. Since the running rails of DC railways must be installed insulated from the earthing system, damage to connected electrical equipment, e.g. track release systems or point machines, can be caused by increased potential in the running rails as consequence of lightning strikes. To avoid damage by lightning strikes and overvoltage, lightning arresters between the running rails and the earthing system are recommended. Figure 12.30 shows the protection circuit diagram in the substation and at the overhead contact line [12.31, 12.32]. The resistance to earth of an earth electrode for a lightning arrester should be below 10 n [12.33].
12.5.5.11
Third party earthing installations
Cable screens, pipelines and metallic and steel reinforced structures in third party systems can transfer potentials and also cause stray current corrosion on third party equipment. Pipelines from outside, into the tunnel or onto the viaduct in a railway system, must be laid with insulation against the structure earth, or be separated electrically by means of insulating sections at the entry points into the buildings. This also reduces natural corrosion due to different open-circuit potentials in the earthing system. The screens of communications cables that lead to the railway system from outside, must also be insulated against the structure earth. Despite this, to take advantage of the reduction effect, the cable sheaths can be connected to the structure earth via low-inductive capacitors. DC railway installation and underground pipelines and cables should be arranged as far away from each other as possible. According to [12.13], a minirnum distance of 1 m should be observed.
12_.5 Direct-current traction systems
669
The earthing installations of third party systems are insulated from the DC railway system earthing structures. If such an insulation is not possible, e.g. if the DC railv::av system and third party systems are integrated into large building complexes, then the earthing system of the entire complex must be grouped together with the earthing system of the DC railway. In this case, the entire building complex must be insulated from other third party earthing systems. 12.5.5.12
Construction of DC earthing installations and provisions
The principles for earthing and stray current protection for DC railways are important for the construction of each electrification project. Electrical connections in the reinforcement of buildings, bridges, tunnels and pole foundations must be defined in due time before the first construction activities. If the earthing connections and throughconnections have not been provided in the structures, then alternative solutions must be provided later, adding considerable additional costs. It is especially important to reach early agreement on the materials, cross sections and connection techniques to be employed to fulfil the requirements for the earthing of electric rail way systems. The minimum cross sections of earthing conductors are specified in [12.10, 12.28] with respect to corrosion and mechanical strength, for example 50 mm 2 for steel and 16 mm 2 for copper. According to [12.40], welded connections are preferred to clamp connections for earth conductors, since the electrical resistance at the connection could be increased by corrosion of the clamps. 12.5.5.13
Verification measurements
Verification measurements are recommended to check the electrical connections of the reinforcement before the concrete is poured, since short-comings can only be corrected at great expense. The continuity of the return circuit must be tested and the safety measures in the system verified during the commissioning of the track.side facilities. It must also be verified that the necessary provisions against stray current corrosion haYe been undertaken. Measurements can be necessary for verification of parameters such as the resistance to earth and during operational conditions, rail potentials, leakage current between running rails and earth as well as potentials between the structural earth and return circuit.
12.5.6
Practical experience with the Ankaray LRT system
12.5.6.1
Description of the project
The provisions described above have been implemented for earthing and bonding for the Ankaray LRT in Ankara, Turkey, as illustrated by Figure 12.27. The project is introduced in clause 1.5. During construction and commissioning phase verification mea.surements ,vere carried out.
12 Current return circuit and earthing
670
-400-!,..---+--f--+---+--f--+----+--+--+---+--1-·· -.~
Figure 12.31: Ankaray: -I-·'· . ...
I
-600
2 ,
-525 mV
-+
~~-~~-~~-~~-~~-~~-~
0
20
40
60
Time---..
12.5.6.2
80
100
s
120
Potential between tunnel structure and remote earth during train operation.
Measurement of the resistance to earth
The resistance to earth of all stations and substations was measured during the construction phase using the 3-probe method. The maximum value measured was 0,35 n. This was significantly lower than the value of 0,9 n required for compliance with the permissible touch voltage in case of three-phase supply earth faults. 12.5.6.3
Measurement of rail potentials
During the system trial run, the rail potentials were measured at the stations, operating the shortest permissible train headway and under maximum pull-train load. During normal operation, maximum rail potentials of ±60 V occurred. Feeding sections were through-connected to investigate the effect of substation outages. Higher rail potentials occurred during multiple starting, causing tripping of the short-circuiting devices in the stations in some cases. 12.5.6.4
Test of rail insulation
To test the insulation of rails, the conductivity between the running rails and structure earth was measured using the method described in (12.13]. The measured values were close to 0,02 S/km per track, significantly lower than the 0,1 S/km, recommended for the planning of tunnel sections and used for design. During the measurements, the longitudinal resistance of the running rails was also measured. The values were found to be between 36 and 40 nm/km for one running rail and correspond very well with the value specified in relevant documents for the rail type S 49. 12.5.6.5
Measurement of the potential between structure earth and earth
For assessment of the danger of stray current corrosion the potential of the tunnel structure was measured against a Cu/CuSO 4 reference electrode, without vehicle operations and during maximum operational load. Figure 12.31 shows a print out of a typical measurement, result. The average pot;ential between the tunnel structure and
12.5 Direct-current traction systems
671
remote earth during train operations is insignificantly higher than that occurring without operations. Only short duration voltage peaks of up to 50 m V occurred because of train operation. Since the average value of the measured voltage shift was far below 100 mV, in accordance with [12.13], there is no danger of stray current corrosion. 12.5.6.6
Current through short-circuiting devices in the stations
A quantitative assessment of the stray currents is possible based on a current measurement with short-circuiting devices closed for testing purpose. This circuit connects the running rails with the structure earthing system and has an effect similar to the stray current drainage. Even in this unfavourable case, stray currents smaller than 10 A were measured at the short-circuiting device. This, low value confirms the high quality rail insulation used for the Ankaray metro system, especially in comparison with other DC railway systems. Without the intentional connection, the values corresponding to the calculations in accordance with clause 12.5.4 are assumed to be lower by a factor of 10. If several short-circuiting devices were closed simultaneously, then considerably higher currents up to 500 A - would flow through the connecting cable, in this case, the through-connected tunnel reinforcement would be connected in parallel to the running rails.
12.5. 7
Maintenance
The measurements at the Ankaray metro system show that an overall strategy for earthing and bonding and the arrangement of the return circuit not only benefits the project progress but also simplifies the maintenance of the earthing system with respect to safety of people and the effectiveness of the stray current protection. The currents in the short-circuiting devices (see clause 12.5.6.6) should not be significantly higher than the values during the system commissioning at comparable train operation. The rail potential measurement also permits a qualitative assessment of the stray current conditions. The measurement can be performed at the terminals of the shortcircuiting devices during train operation. The danger of stray current corrosion would be increased when the average value of the rail potential changes under the same operational conditions compared to the commissioning measurements. The reason can be low resistive connections between the return circuit and the structure earth, vvhich can be located by further measurements. A low rail potential indicates the proximity of faulty connections between the running rails and structure earth. At great distances from the faulty connection, the rail potential increases to double the value compared to undisturbed operation. If the current and voltage measurements show extraordinary large deviations from the reference measurements, a test of the rail insulation and the structure/ earth potential in accordance with clause 12.5.6.4 and 12.5.6.5, respectively is recommended to localise the cause.
12 Current return circuit and earthing
12.5.8
Concluding recommendations
The system design of the traction return circuit, including earthing and bonding described in this clause, is based on insulated running rails and a uniform earthing system. It complies with the European standards. The example of the Ankaray metro system and of other installations demonstrates that this design has proven itself in practical applications and simplifies maintenance. The configurations with stray current collecting nets also discussed, would cause technical disadvantages and require additional expenditure for construction and maintenance. Stray current collecting nets and stray current drainage, as a method for stray current protection, can not be recommended. The measures for earthing and bonding also affect aspects of civil works and must be defined at an early stage of railway projects to allow the necessary provision prior to construction to avoid expensive extra compensating measures. In summary, Figure 12. 27 shows the recommended system for current return and earthing of DC lines to provide protection against electric shock and stray current corrosion on line sections in tunnels and on viaducts.
12.6
Alternating current traction syst~ms
12.6.1
Design of the return circuit and earthing installations
12.6.1.1
General
The systems that are used for the power supplies of AC railways also affect the return current system. In simple return conductor systems, Figure 12.1, using the running rails as the return circuit 30 to 40 % of the return current, flows through the soil. Thisproportion can be reduced to 15 to 20 % by installing return conductors at the poles as shown in Figure 12.1 b). The auto-transformer system shown in Figure 12.1 d) feeds the railway track at a higher transmission voltage between the overhead line and the energised return circuit. It is often known as the negative feeder. Auto-transformers, arranged at intervals of 10 to 20 km, transform the transmission voltage to the contact line voltage. Two neighbouring auto-transformers function as two conventional substations on track sections supplied at both ends. The feeder and return currents flow, as in the case of booster transformer systems, in close proximity to each other. They also reduce the return current flowing through the running rails and earth. The booster transformed system, Figure 12.1 c), employs transformers with a transformation ratio of 1:1 connected into the overhead line at intervals of 3 to 5 km. The secondary winding sucks the return current from the running rails via connecting lines into an 'insulated suspended return conductor. It flows back to the substation in close proximity to the contact wire. The cmrent flowing through the running rails and the earth is very low over large sections of the line. The r<~tmn circ11it on AC railways. contrary to that on DC lines, is connected to
12.6 Alternating current traction systems
673
earthing systems. The earthing systems include large area earth electrodes such as building foundations, bridge and viaduct foundations, tunnel reinforcements and piling foundations for overhead contact line poles along the track. Their interconnection via the return circuit line forms the railway earth to which the following are connected: mediurn-voltage protection earth, - low-voltage protection earth, - earthing of telecommunications and signalling, as well as earthing of lightning protection devices.
With AC traction systems, the earth is part of the traction current return path clue to the inductive and ohmic coupling with the tracks. Parts of the track return current flow through the connected earthing systems and through the soil. This results in an extended area within which non-railway installations may be affected by the railway system. The stronger the current flowing through the earth, the higher the risk of other installations, pipes, cables and devices in the vicinity of the railway being affected by inductive and galvanic coupling. To counteract this problem, various strategies have been developed and implemented to reduce the proportion of the traction current flowing back through earth, reducing the associated effects.
12.6.1.2
Current return through rails and earth buried return conductors
Clause 12.4.3, explains how the rail potential in a system through which a load current is flowing can be reduced noticeably by installing strip-type earth electrodes. This is also confirmed by the values in Table 12.5. Such earthing strips are also suitable for potential control. A separate earthing strip is buried approximately 1 m underground for each track. Usually, these strips are made of galvanized steel with a minimum zinc coating of 70 µm thickness and a cross section area of 30 x 4 mm 2 , or of 50 mm 2 tin-plated copper cable. Because of their underground installation and the cross sections used, the earthing strips only lead to a slight improvement in the return current conductance characteristics. For DB overhead contact lines, it was calculated that in comparison to lines without earthing strips: the absolute value of the overhead contact line impedance is reduced by approxi:nately 2 to 3 %, the longitudinal voltages induced in conductive parts located at a distance of 3,5 m from the track centerline and 0,1 m above the rail hea~l are reduced by roughly 7 %, and the track-to-earth voltage is reduced by approximately 53 %, if earthing strips are installed. The shape and the field strength of the electromagnetic .field in the area surrounding the railway line barely changes when earthing strips are installed. So the main advantage is the reduction of track-t:o-eart:h voltage.
12 Current return circuit and earthing
674
substation
traction vehicle
,,,c 1,0
t 0,75 ' C
0
5 .D
I /
"
........
~ 0,50
c
.,
~
=i
/ /
0,25
0
_.
/
/
in the track
'6
0
- --------
/
____ in the track_
_ _ _ _ ,w._ _ _ _
-------- --------
-
in the retyrn conductor
-
"" ~
in the earth n'r•-'-----,... -
.......
in the earth
0
12
8
4
16
20
km
24
Length-
90
__ ,
V
kA·km
70 60 50 40
U'i
30
Ti;
20 10 0
--- -
40
12.6.1.3
___ ...... -
30
----~ 20
____ ,,,.,,,.
...
\
I
\•I
--
i--
10
I
\
I
I
--,
p H \ 1\_r-Yl
••
...................
----
10 0 Distance-
.......... ____
-----20
- ---
30 m 40
Figure 12.32: Distribution of the return traction currents among the individual return paths of a double-track line with an effective leakance per unit length of 2 S/km. - - without return conductor with an Al 240 return conductor Figure 12.33: Ratio of the longitudinal induced voltage per unit length of conductors installed parallel to a railway line to the traction current for f!E = 100 Dm. - - without return conductor with an Al 240 return con,. ductor
Parallel return conductors
A simple and effective way of reducing the proportion of return current flowing through track and earth in overhead traction energy supply systems, is to install parallel return conductors in the vicinity of the overhead contact line equipment and supplementary feeder lines. Parallel return conductors, with a close inductive coupling with the traction current feed conductors, have the following measurable effects: Installing parallel return conductors considerably reduces the proportions of return current flowing through track and earth, as shown in Figure 12.32. Track-to-earth voltages, i.e. rail potentials are also lowered considerably. Calculations have shown that a reduction of rail potentials by 50 to 55 %, with reference to systems without return conductors, can be expected. Reference [12.41] reports that a 53 % reduction was determined by measurement after return conductors had been installed. Longitudinal voltages induced in conductors installed parallel to the railway line are halved approximately. For a DB standard contact line of type Re 250 with return conductor, it was found that the induced longitudinal voltage in a conductor located 3,5 rn from the track centerline was almost 45 % lower than with an
12.6 Alternating current traction systems
675
overhead contact line without parallel return conductor. Measurement of induced voltages on a conductor at a distance of 11 m parallel to the Madrid-Seville railway, which is powered by a 50 Hz single-phase AC supply, gave values of 43 V per km and per kA traction current (see clause 12.6.5 and [12.42]). Calculations carried out for a comparable system, without parallel return conductors, showed that the value would be 70 V /(km-kA). In other words, a reduction of approximately 39 % had been achieved. In [12.41] the interference voltage is shown to be almost 45 % lower when parallel return conductors are installed. From Figure 12.33 it can be deduced that the installation of parallel return conductors will reduce induced longitudinal voltages by between 35 and 40 %. The rnagnetic .field in the vicinity of the railway line is reduced considerably. In reference [12.41] it was shown that the magnetic field strength at rail height and at a distance of 12 m from a contact line of type Re 200 is 9 A/m if parallel return conductors are installed and 18 A/m when no return conductors are installed. For a 12 m distance, reference [12.43] reports values of 10 A/m with parallel return conductors and 19 A/m without return conductors. This reduction of the magnetic field strength, due to parallel return conductors, can also be seen in the graphs in Figure 13.17. The impedance per unit length is reduced. Paper [12.41] reports that a reduction of the impedance per unit length by 9 % relative to the variant without return conductors was measured on a AC 15 kV 16,7 Hz line. At the same time, the resistance per unit length was increased by more than 8 % relative to the calculated value and the reactance per unit length was decreased by more than 18 %. As a result, the phase angle changed from 56° to 48°. Figure 12.32 shows the distribution of the return flow of the traction current in the rails and earth. If a return conductor, at earth potential, is installed along the poles at the same height as the overhead line equipment, then almost half the current normally flowing back through earth is uncoupled from earth and flows back via the return conductor, as indicated in 12.1 b). The values shown in Tables 10.10 and 10.11 also indicate that the parallel return conductors approximately halve the proportion of return current flowing through earth. If the investment required to install and operate the systems described above is compared for improving return current conduction in single-phase alternating current railways, the solution involving the installation of parallel return conductors proves to be the most favourable. A contact line installation with parallel return conductors involves barely 5 % more expenditure than one without. The noticeable reduction in the magnetic field strength in the vicinity of the railway, the interference voltage reduction and the reduction of track-to-earth voltages and impedance justify this additional investment and effort. Reference [12.44] comes to the conclusion that, for the Austrian railway company OBB, a return current configuration involving the installation of parallel return conductors along high-traffic-load lines is an economically and technically sound solution to the problem of return traction currents and the associated issues of interference and disturbance.
12 Current return circuit and earthing
676
Return conductor
Contact line
Running rails
1
2
3
4
~ Earthing systems
Figure 12.34: The earth return current and earthing of AC railways using return conductor lines. 1 High- and medium-voltage protective earthing 2 Low-voltage protective earthing 3 Earthing of telecommunications and signalling systems 4 Lightning protection earthing
The modification of the return circuit using the running rails to provided earthed return circuit lines, as shown in Figure 12.34, combines simple design with the conduction of the return current in close proximity to the catenary system. This design is employed, for example, on the Madrid-Seville high-speed line and is used for new DB AG routes in Germany, e.g. the high-speed Berlin-Hanover line [12.45]. By arranging the return current lines close to the contact line, good inductive coupling is achieved. This reduces the portion of the current flowing though the soil and has a positive effect upon disturbance voltages, magnetic fields and rail potentials.
12.6.1.4
Auto-transformers
The a'Uto-transformer principle has been explained in clause 1.2.5. This principle, which can also be implemented in a modified form with double the nominal voltage between negative feeder and earth, can be applied to all single-phase alternating current railways where the supply of traction power to the railway line is problematic. However, the advantages of this feeding principle as mentioned in clause 1.2.5 are also accompanied by several disadvantages, including the following: the train-in-section e.fj'ect is considerable because the distance between the autotransformers is usually quite large, track and earth currents, albeit small, still flm\· in all sections between the autotransformers, the auto-transformers increase the currents occurring during short circuits in the traction energy network. and prntcctwe prmnsions im·olve a considerable amount of effort.
12.6 Alternating current traction systems
677
Further detailed explanations on this feed concept are to be found in references [12.46] and [12.47]. An application is described in [12.48]
12.6.1.5
Booster transformers
Figure 12.1 illustrates the principle of operation of draining or booster transformers. From the feeding substation transformer onwards, the contact wire is interrupted at 3 to 8 km intervals and the traction current is passed through the primary winding of a transformer with a transformation ratio of 1:1, called booster transformers. The secondary winding of the transformer is connected to a return current conductor, called the return feeder, which passes the traction current back to the feeding substation. Such booster transformers inductively cancel the current at the position of the load, i.e. they drain the current from the rails and earth and pass it into the return feeder. The booster transformer system considerably reduces interference effects. The disadvantages of this concept are the high cost of installing and operating a large number of booster transformers, return feeders and switchgear, especially taking into account that each track of a multiple-track line has to be equipped with booster transformers, increased effective line impedance due to the booster transformers, this being associated with increased potential drops and power losses, arcing across electric isolation gaps in the contact line network, leading to faster contact wire and collector strip wear, as well as radio frequency interference, and the train-in-section effect, i.e. when a traction vehicle is travelling and drawing a current between two booster transformers, currents will still flow through the rails and earth, depending on the distances and the track parameters involved. Almost two decades ago, booster transformers originally installed during the electrification of railway lines in Taiwan ·were decommissioned after only a brief period of operation; the return feeder cables were reconnected subsequently as simple return conductors [12.49]. In reference [12.50], a further development of this principle is suggested. The idea involved connecting cables in parnllel to both the contact wire and the running rails. If the two cables are placed as close as possible to one another, then the reactance of the overall system is considerably lower than a comparable system without such cables. However, installing and operating a system of this kind would lead to high investments and efforts and the train-in-section effect would also persist in a system of this kind. For this reason, no practical applications of this suggestion are known to date.
12.6.2
Requirements of return circuit and earthing installations
12.6.2.1
Personal s::i.fety
Primarily, the earth return current and earthing of AC railways must prevent haza.rcls of electric shock and gt1ara11te<' personal safety [12.51]. To achieve this, electrical <'quipment and components of the overhead contact line svstem. that cot1ld become
12 Current return circuit and earthing
678
1
/--~------- __ , / _______ _ /
I
'
'-...
2
Distance to the substation - - -
Figure 12.35: Rail potential along the track in the operating case and in the short-circuit case. 1 related track potential U' at constant traction current (operating case) 2 highest rail potential U occurring during short-circuit 3 short-circuit current h depending on the short-circuit distance from substation
energised at contact line voltage under fault conditions, are bonded directly to the traction system earth. This especially applies to parts that lie within the contact line and pantograph zones that could be energised at contact line voltage after the breakage of the contact wire or dewirement of a pantograph. The traction system earthing of this equipment and these components results in reliable protection tripping, e.g. during insulator flashover or short circuits between the overhead contact line and poles, guaranteeing personal safety. If a direct connection to the AC traction system earth circuit is not possible, because for example, the parts to be earthed are part of a return circuit belonging to a DC railway, then they are to be to connected to the return circuit of the AC line using voltage fuses. This is referred to as open traction system earthing. Small conducting components, whose horizontal length does not exceed 2 m and do not support electrical equipment, are excepted from the earthing according to EN 50 122-1, clause 5.3.2 [12.1]. The rail potentials must also satisfy the requirements for touch voltage protection. The injection of traction currents into the return circuit at the location of the vehicle causes a local potential increase of the return circuit against earth. This potential difference, the rail potential is dependent upon the operating and short-circuit currents, the leakance of the track to earth and the distance of the vehicles or the earth fault from the substation. Normally, the rail potential is referred to 100 A as a specific value. The specific rail potential has a value of zero at the substation and only reaches its maximum value at a distance of 0,5 to 5 km. The trend along the track is illustrated in Figure 12.35. The maximum rail potentials need to be calculated for the operational and short-circuit cases to assess the hazards caused by the rail potential. For a constant operational traction current, the maximum occurring rail potential rises with increasing distance up to a distance of 0,5 to 5 km of the vehicle from the substation and then remains almost constant, dependent upon the earthing conditions. Figure 12.35 illustrates the corresponding trend of the highest rail potential occurring along the track. Since the vehicles draw more current with increasing distance from the substation because of the constant power, the highest rail potentials occur at the greatest distance from the substation. The short-circuit current is largest for a short-circuit at the substation but the specific
679
12.6 Alternating current traction systems
"' TTrack E Earth P Measuring ooint
UTP
UpE
r-- -0-
-=-
1,~----i a p T
I
E
0,5
5
a---
m
100
,; !' '
'
'i
Figure 12.36: Potential trend transversally to track according to [12.10] Table 12.8: Permitted touch voltages and rail potentials. U touch voltage; UTE voltage between track and earth; tp fault disconnection time Permissible value for touch voltage V
V
Urn= 2V
(V]
[V]
Operational case (t > 300 s) Operational case (t = 300 s) Fault case (tF = 100 ms)
60 65 842
120 130 1684
rail potential, however, is zero. The absolute value of the rail potential reaches its maximum only at a distance several kilometres from the substation in the transitional area shown in Figure 12.35, where the specific value for the rail potential is still increasing. To assess a hazard caused by the rail potential, the trend of the potential against earth must be considered transversally to the track. Figure 12.36 illustrates the fundamental trend UPE at the ground surface against earth and the potential trend UTP against the running rails relative to the rail potential U,fE. The value UTP for the distance of 1 m from the outer rail corresponds to the touch voltage. It must be recognised, that the full voltage UTE cannot be bridged at a distance of 1 m. According to [12.1], it is approximately 20 %. For the earthing of high voltage systems, [12.10] and [12.52] assume 50 % anc: specify that the touch voltage is considered to be compliant if the earthing voltage does not exceed twice the perrnissible touch voltage value. This statement, transferred to the mil potential, is taken into account in Table 12.8. The touch voltages specified in [12.1] also apply to fixed power supplv installations,
I I !,'I
J.
12 Current return circuit and earthing
680
where faults with earth contact within the three-phase medium- and low-voltage systems must be taken into account. For this, the potential increase of the earthing system is to be treated in the same manner as the rail potential. The values for the permissible touch voltages and rail potentials in the short-circuit case shown in Table 12.8 take account of the fault disconnection times of modern protection devices, which are less than 100 ms. Potentials can be transferred into the railway system from other earthing systems because of conducting connections. Precautions are necessary to avoid inpermissible touch voltages, e.g. local insulation or covering. 12.6.2.2
Interference
The following types of interference are examined with regard to track return current and earthing: resistive interference, - inductive and capacitive interference and - electric field and magnetic fields. The resistive interference arises from conductive connections with the return circuit. Capacitive interference plays an insignificant role in railway applications. Inductive interference and magnetic fields are important in AC railway systems. Their magnitudes are dependent upon the self-impedance and coupling impedance of the overhead line arrangement, in the same manner as the return current distribution. For this, the return current through the earth represents a measure of the interference. Additional return circuit conductors reduce the return current flowing through the earth and therefore the interference in the vicinity of the system. The interference affects railway-owned and third party electrical devices in the direct neighbourhood. Impairments and disturbances can occur, depending on the sensitivity of the equipment (see chapter 13 for details).
12.6.3
Design of installations
12.6.3.1
Return circuit
The return circuit, the electrical equipment enclosure and the conducting components in the area of the overhead contact line system are connected to the railway earth to avoid hazardous touch voltages during operations and during short-circuit faults. Figure 12.37 shows provisions that satisfy this requirement in a simplified circuit diagram. The individual earthing systems for bridges, tunnel segments, substations and pole foundations are connected to the return circuit and form the overall earthing system for an AC railway system. This guarantees the earthing of the return circuit at the same time. The running rails, the return circuit lines and the connecting lines to the substation form the return circuit in accordance with Figure 12A To achieve as low a voltage drop as possible, welded connections are preferred and the points are bonded longitudinally with a low-resistance joint To distribute the return currents evenly among
12.6 Alternating current traction systems
681
signal
••
fence
screened cables return circuit staion
substaion
traction power supply
station power supply
*
*
l
l structure earth
i
i
railway-owned installations
------------------------ ----·------------------------------------- --------------------------'
pipes with insulation joint
third party installations
Figure 12.37: Principle circuit of earth return current system and earthing for AC.
all parallel tracks and return circuit lines, they must be bonded to each other. The intervals between the transverse bonding are defined relative to the earth electrode resistance of the return circuit conductor and the permitted touch voltage. It normally varies between 600 and 1200 m. Longer transverse cross-bonding intervals can be selected for converter-supplied track sections supplied by substations equipped with power-electronic converters, since the converters limit the short-circuit currents. The requirements of the track-release circuits must be taken into account for the intervals between the cross-bonding. The return currents in the substation flow through the return circuit and earth connections to the insulated return current rail, see Figure 12.38 [12.53]. Twin return conductors must be provided between the track and the substation and designed in such a manner that they can carry the whole current after a failure of one of the conductors. Recording of return currents, as provided in the design of return current system shown in Figure 12.38, permits testing of the return circuit. The current transformer 11 measures the whole railway return current if the cables from the return current bar to the transformer are insulated against earth. The portion of the return current through the earthing system is measured using the current transformer 12.
12 Current return circuit and earthing
682 C
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ME Main equipotential busbar
Return current bar return circuit Lightning protection
Lightning protection
.---"---.,-"--..,.-<--------------------
·m
a: OJ C
·c C ::J
a:
Figure 12.38: Railway return current and earthing in the substation for AC.
12.6.3.2
Substations and stations
Normally, the traction power to substations is supplied decentrally from the public energy supply network for new lines but 3:~so from railway-owned high voltage networks by some railway operators, such as DB, OBB or SBB. The high-voltage supply and the railway substations have a common earthing system. All operating assets in the high-, medium- and low-voltage supplies are connected to it for potential compensation and safe protection tripping, as shown in Figure 12.37. The sheaths of cables employed to connect the substation with the contact line on the tracks may be earthed at both ends only if they can carry the whole traction current. In the case of one-ended earthing, high voltages can occur at the free end of the cable sheaths. The sheaths' ends are to be insulated against touching in this case. When the low-voltage supply is provided from the public network, the protection earth and the neutral conductor of the low-voltage system should not be connected to the AC railway earth. They could be endangered by the railway return currents. The traction currents of all vehicles are added to each other in the substation and lead to a potential increase at the earthing system. When earth short-circuits occur in the high-voltage supply, the earth short-circuit currents flow through the earthing system. It is necessary to have an especially low earth electrode resistance in the substation earthing system, to achieve a low earthing voltage. Figure 12.38 illustrates the earthing system and the potential compensation in the substation. The main equipotential busbar (ME) does not carry railway return currents to avoid voltage fluctuations in the connected centralised infrastructure management system, telecommunications system, three-phase supply system, signalling system and in the operating equipment enclosures. The ME is therefore connected to the earthing bus bar of the earthing system at one end. The foundation earthing connections are connected to each other and attached twice to the earthing bus bar. These connections must also be designed to carry the maximum operating and short-circuit currents in the event of a failure of one of the earthing connections. Since the station platforms are also located in the overhead contact line zone and
12.6 Alternating current traction systems
683
pantograph zone, the reinforcement of concrete structures must be connected to the railway earth. The platform foundations should be designed as earth electrodes to reduce the earth electrode resistance of the system as well as the rail potentials. 12.6.3.3
At-grade sections
'
Contact line poles and overhead line fittings on the earth side along at-grade sections should be connected to the railway earth, as they are located in the contact line and pantograph zone. If the return current conductor is connected electrically at every pole to the pole reinforcement (of concrete poles) or to the steel poles, the connection of each pole to the railway earth can be waived. The earthing of the return circuit along the track is provided by the foundation reinforcements. They are connected to the mast reinforcement and the return circuit line. The omission of the individual earthing of each pole along the track also offers significant savings during maintenance of the superstructure and the earthing systems. In addition, a considerable increase in safety results from the more reliable connection of the poles to the railway earth than from a direct connection to the return circuit [12.54]. 12.6.3.4
Tunnel sections
Steel reinforced tunnels form earth electrodes along the track. Both the tunnel rein-
forcement and the overhead contact line components are connected to the railway earth to reduce rail potentials and guarantee potential compensation and protection against touch voltages. It is possible to connect individual reinforcement sections to the return circuit, making the practice of longitudinal bonding superfluous. Additional earth connections to the return circuit may be used to connect overhead contact line components to the railway earth in tunnels and to other concrete structures. The necessity of providing such additional connections, in case of components arranged on unistruts was tested, using the example of the new high-speed line CologneRhine/Main. If the unistruts are connected electrically to the return circuit, additional earthing connections from the components to the railway earth can be omitted. Measurements of the short-circuit resistance of fixing bolts and rails manufactured from stainless steel, have shown that the permitted heating was not exceeded for thermally effective short-circuit currents of 33 kA over a fault period of 350 ms. It is sufficient to connect the unistrut to the railway earth at the return circuit. Tunnels with sealing systems against the penetration of ground water (welded 4 mm PVC sheaths between the inner and outer tunnel shells) lose contact with the sc,il and the earthing e.ffect of the tunnel. Because of the danger of potential transfers at the emergency exits, which, in accordance with national safety codes may not be more than 1000 m apart, additional earthing measures are necessary if the rail potentials can cause unacceptable touch voltages. The high traction eunents of up to 1,5 kA per train in the tunnels on the CologneRhine/Main high-speed line and the sealing of the tunnels against penetration by ground water, results in unfavomable conditions for the earthing of the system. With i11creasing tu1111el length, the rail potent?:als reach increasingly high values and exceed
684
12 Current return circuit and earthing
Figure 12.39: Tunnel earth-
ing with standard reinforcement mesh and parallel return conductors. the permitted values by a factor of two. As long as no potentials are spread into the tunnels from outside, humans cannot pick up the voltages to earth in the tunnel. The design of the tunnels, with emergency exits, leads to the possibility that the potential differences at the exits can be picked up by members of staff for example. Measures were taken to lower the rail potentials to permitted levels. These measures consisted of the following: an earth strip electrode laid in the outer tunnel shell, which is led through the sealing into the tunnel every 500 m and connected to the return circuit ring earth electrodes, which are arranged around the emergency exits to control the potential and reduce the earth electrode resistance. In conclusion, the following provisions are to be made in tunnels to ensure safe traction current return paths, traction earthing and equipotential bonding: The tunnel floor area should be earthed to ensure good earth contact. Longitudinal earth strips must be installed at a spacing of not more than 1,5 m across the width of the track in the overhead contact line zone to ensure that a short-circuit current will flow in the case of contact wire breakage, tripping the circuit breaker in the feeding substation. Longitudinal conductors of this type are also used for potential bonding along walkways and for protecting cable conduits. The running rails, too, are longitudinal conductors. Bare conductive strips may be installed in a longitudinal direction as shown in Figure 12.39. These longitudinal conductors, which the DB calls bouncing contact strips are designed to ensure a short-circuit if a broken overhead contact line should touch the tunnel wall. As the investigations described in [12.6] have shown, it would not be necessary to install deflector contact strips as the earth strips installed on the concrete surface mentioned above will always lead to a short circuit. Installation of return conductors, or interconnecting all longitudinal reinforcement rods, is the recommended solution. Return conductors can substitute for the longitudinal bonding of the reinforcement
12.6 Alternating current traction systems
685
longitudinal reinforcement rods \ return conductor
Figure 12.40: Arrangement of conductors in a tunnel.
rods in this area. A return conductor installed separately over each track can serve as the earth busbar for all components that need to be connected to traction earth. These conductors are connected to the rails on the tunnel floor at intervals of approximately 300 m. In tunnels with double track, such connections are designed as loop conductors and also serve as track bonds. Figure 12.40 shows tunnel earthing arrangements in a tunnel with return conductors. 12.6.3.5
Viaducts
The drilled piles and foundations of viaducts also form additional earth electrodes along the track. To utilise their earth electrode effect, the reinforcement of the individual viaduct segments is connected electrically via the supports down to the base of the foundations. The contact line system poles on the viaduct are to be handled in exactly the same manner as the at-grade sections. The poles are connected to the viaduct reinforcement instead of the reinforcement in the pole foundations. The electrically interconnected reinforcements also form lightning arresters for the viaduct. These connections should be kept as short as possible, to keep the resistance and inductance in the arrester path to a minimum. I I
!
12.6.3.6
Depot and workshop area
No special earthing measures are necessary in the depot and workshop areas of AC raihvays. The same values for touch voltages, as permitted on the track, apply for durations of up to five minutes. A touch voltage of a maximum 25 V is defined in EN 50122-1 for long term processes of more than 5 minutes duration in depot and workshop areas [12. 1]. This limit value is to be observed especially for the air conditioning and the preheating of trains.
i''
I 12 Current return circuit and earthing
686 Protective fence
Flat steel bar
Figure 12.41: Earthing measures at road bridges (DB AG, Germany).
12.6.3. 7
Signalling and telecommunications systems
The cables of signalling and telecommunications devices can spread voltage over long distances. Voltages caused by inductive interference can also arise. Plant components in the signalling or track release system lie within the overhead line zone. They are connected to the running rails and therefore to the railway earth. The connections are designed to withstand short-circuits. Telecommunication and signal cables are influenced by the traction power supply system. The cable sheaths are connected at both ends to the earthing systems in the stations and along the track to reduce interference. Since operational currents from the traction power supply flow through the cable sheaths, attention must be paid to providing the cable sheaths with sufficient current capacity. 12.6.3.8
Third-party installations
Third-party earthing installations in the vicinity of the track should not be connected to the railway earthing system because of the danger of spreading potentials. For this reason, pipework from outside should be manufactured from non-conducting materials or interrupted at the site boundary by the use of an insulating segment as illustrated in Figure 12.37. If a separation between the railway and public supply network earthing systems is not possible due to lack of space, the return circuit may be interconnected with the neighbouring earthing system in the public networks. A satisfactory cross section for the conduction of railway return currents must be provided for this. As an example, DB AG permits the operation of a three-phase star point conductor without special protection measures only over a distance of less than 1,5 km along the AC raihvay system [12.55]. If components of crossing mad bridges lie within the overhead contact line and pantograph zone, then EN 50122-1 [12 . 1] and the DB AG directives [12.53] specify special
12.6 Alternating current traction systems
687
Table 12.9: Surge earthing resistance for 15 kV railways.
Withstand surge voltage Discharge earthing resistance
Overvoltage category III IV 75 kV 95 kV 1,9 n 2,4 n
earthing provisions to ensure personal safety. Figure 12.41 illustrates recommended designs: galvanised steel strip on both bridge walls, if these are located in the overhead contact line zone, galvanised steel strip or angle section-profile above the overhead line at the start and end of the bridge if the bridge roof is within the pantograph zone and protective fence or projecting contact-protection on the bridge sides. The metallic parts are connected at two points to the return circuit. It is recommended that the reinforcement of new bridges is additionally interconnected electrically and then connected to the railway earth for lightning protection. The bridge foundations can also be employed as earth electrodes in this case. 12.6.3.9
Lightning protection
Railway systems are to be protected against damage by lightning. On open track sections, the return circuit together with the poles, the overhead line equipment pole foundations with contact to the ground and the associated reinforcement also perform the task of external lightning protection. The earth connections should be kept as short as possible, to keep the resistance and inductance in the arrester path to a minimum (12.52]. Suitable overvoltage protection circuits, in addition to the external lightning protection, are adopted to protect sensitive equipment assets. Evaluations of the frequency of lightning current in accordance with VDE 0141 [12.52] have shown that 95 % of all lightning currents are smaller than 40 kA and 99 % smaller than 60 kA. Back flashovers are not to be expected if the discharge earthing resistance Rdis satisfies the relationship (12.35) Rdis Uin
Ip
discharge earthing res·istance withstand surge voltage of the insulation peak value of the lightning current in mast or framework
For earth electrodes of small size, such as pole foundations, the surge earthing resistance corresponds approximately to the earth electrode resistance. The necessary dischar:qe earthing resistance for a lightning curreut Ip of '10 kA in dependence upon the overvoltage category for 15 kV railways are entered in Table 12.9.
I
12 Current return circuit and earthing
688
The permitted values for the surge earthing resistance increase due to the higher withstand surge voltage of the insulation used for 25 kV railways. This enables the requirements for the surge earthing resistance to be satisfied more easily than for 15 kV railways. 12.6.3.10
Implementation
The earth return current and earthing provisions have a special impact upon steel reinforced concrete structures and must be defined at an early stage before the execution of construction. The electrical connection of the reinforcement, the additional provision of reinforcement rods and earthing lines in the foundation. The lead-out of the earthing connections are necessary during the first implementation phase. They must be initiated much earlier than the detailed planning of the electrical system, especially for railways on viaducts with long lead times for the construction work. This includes the timely agreement of materials to be employed, cross sections and connection technology for the structure earth, to satisfy the requirements for the earthing of an electrical railway system. If the earthing connections and electrical throughconnections have not been provided on the structures and are lacking during the installation of the electrical systems, then alternative solutions must be provided later. This can cause considerable additional costs for the implementation of the system. The electrical connections between the reinforcement rods should be welded preferably, because the electrical resistance of clamp connections can increase with corrosion at the connection point [12.9]. The defined earthing provisions must be monitored continuously by visual inspection during construction, because errors during construction are difficult and expensive to correct. 12.6.3.11
Verification measurements
The security of the earth return current and the personal safety measures in the system must be verified during the commissioning of the trackside facilities. The verification of earthing provisions can be performed on the basis of calculations during the design phase by measurements made after completion of the system. It is expedient to measure the earth electrode resistance, rail potentials and induced voltages during commissioning to check the parameters upon which the calculations are based. These measurements also serve as reference measurements for the subsequent operation of the system. The earth electrode resistance of the earthing system determines the touch voltages and rail potentials that occur under operational and fault conditions. The measurement of rail potentials is performed by feeding a constant current into the running rails, between two rail connectors. The potential of the running rails is measured against a distant earth. The distance to the next cross interconnection of the return circuit should be as large as possible, to examine unfavourable combinations. The supply to one track represents the normal case, while the supply to one rail represents the short-circuit case. These measured rail potentials can be converted to indicate the operational and short-circuit currents by calculation. The measurements can be used to verify that
I
12.6 Alternating current traction systems
689
the permitted touch voltages will not be exceeded during operational and short-circuit conditions.
12.6.4
Return current conductors and earthing systems used by the DB
12.6.4.1
Track and rail bonds
Track and rail bonds serve to distribute the return currents more evenly and to ensure an equal potential on the respective components. The rails of electric railway lines are connected electrically both longitudinally and across all tracks where ever this is permissible. Generally, fishplate joints between rails are adequate for the longitudinal connection. Fishplate joints in sections with track circuits must be bridged by an additional longitudinal bond. Transverse rail bonds or crossbonds are used to connect both rails of a track. The running rails of a track without track circuits are bonded at intervals of not more than 150 m on general-purpose lines or of not more than 75 m on metropolitan lines and other lines carrying heavy traffic loads. Track and earth reactance coils of 100 Hz track circuits also constitute transverse rail bonds. The previously described FTGS bonds are used in audio-frequency track circuits. Figure 12.46 shows how such bonds can be installed. The tracks of multi-track railway lines without track circuits are bonded by means of track bonds. These are installed at intervals of not more than 300 m on general-purpose lines or not more than 150 m on metropolitan lines and other lines carrying heavy traffic loads. If track circuits are installed, the following rules apply to transverse equipotential bonding: Single-rail insulation: As explained in 12.6.4.2, one of the rails has a higher rail-to-earth resistance than the other. In railway station tracks, the rail which is not insulated is at least connected with the return current system at two points. On longer lines, the long earth rails of adjacent tracks are bonded to one another at intervals of not more than 300 m on general-purpose lines or of not more than 150 m on metropolitan lines and other lines carrying heayy traffic loads. Both rails insulated: It is not permissible to install track or rail equipotential bonds in tracks with both rails insulated as shown in Figure 6.47. In this case, the tracks are bonded by connecting the centre-taps of the reactance coil joints. Figure 12.42 shows how track bonding is implemented between reactance coil joints. Audio-frequency track circuits: If audio-frequency track circuits are installed, the rail nearest to the supporting poles of the contact line system is usually chosen as the earth rail. The earth rails are bonded by means of track bonds, whereby the minimum distances shown in Figure 12.43 are compliant. Usually, equipotential bonds are made of plastic-insulated copper cable type NYY-0,
12 Current return circuit and earthing
690 /
insulating rail joint
----1r-T-----------
reactance coil joint
a
track equipotential bonds between reactance coil joints a< 60m. 1x50mm2 Cu, NYY-O a= 60... 1oom . 2x50mm 2 Cu, NYY-O a 100 ... 300m. 2x70mm 2 Cu, NYY-O
a
Figure 12.42: Implementation of track equipotential bonding between reactance coil joints as used by the German railway DB.
track equipotential bonds between reactance coil joints for a> 300 m; track bonds 1x50mm2 Cu, NYY-O
earth rail track bond
a> 200m with FTGS 9 7 a> 400m with FTGS 46 earth rail
earth rail
Figure 12.43: Minimum distances between track bonds along tracks with audiofrequency track circuits.
normally with a cross section of 50 mm 2 . If these bonds are also used for traction earthing purposes and short-circuits, currents of I(; > 25 kA are to be expected at the respective location, then cross sections of 70 rnrn 2 are installed. If the bonds are embedded in concrete, generally a minimum cross section of 70 mm 2 is required and for I{: > 25 kA, 95 mm 2 cable is used. The bonds are permanently connected to the rails by means of welding, soldering, brazing or other permissible methods.
12.6 Alternating current traction syst,_e_m_s___________________________
a)
--9,5m
9,Sm
3,Sm
3,5m
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for FTGS 46 for FTGS 917
' ---+---"---_---,-~~_=r-- - - - 18 12 1I I I
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b)
691
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11
rn ur
electronics junction box
Figure 12.44: Characteristics of important types of audio-frequency track release circuit bonds. a) S-type-bond; b) terminal bond
12.6.4.2
Track release circuits, traction return current path and traction earth
In the following, the situation of the German railway DB, is used as an example to explain some aspects which have to be taken into consideration with regard to the return path of traction currents and earthing when building and operating overhead contact line installations. DB operating directive 997 [12.9] deals with the respective details. Other railway companies operating single-phase alternating current railways have similar internal specifications and regulations. l_,From the electric energy supply system aspect, the running rails serve to conduct a part of the traction current back to the feeding substation. At the same time, however, the running rails are also used as part of the railway network control and command system circuitry. These information-technology circuits, which are linked with the tracks, are called track circuits. A distinction is made between track circuits operating at frequencies of 42 Hz or 100 Hz and audio-frequency track release circuits which operate at frequencies of 4 to 6 kHz and 9 to 17 kHz. Like all other types of track circuit, audio-frequency track release circuits operate on the principle of axle shunt sensing. Remotely fed audio-frequency track release circuits, abbreviated FTGS in German, are circuits using a frequency of 4 to 6 kHz (FTGS 46) for signalling free track on the main line and a frequency of 9 to 17 kHz (FTGS 917) for signalling free track in railway station areas. Figure 12.44 shows the structure and basic dimensions of the S-type-bonds and terminal bonds of FTGS 46 and FTGS 917 systems. S-type-bonds use copper wire of cross sections between 50 and 600 mm 2 . To enable good conduction of the return traction current and proper traction earthing while also ensuring reliable operation of track circuits, the mutual utilization of the running rails for these purposes must be agreed upon and co-ordinated by the responsible technical departments and strict adherence to the regulations agreed upon is required. From the electrical engineering aspect, track design for return traction current conduction and traction earthing distinguishes betv.reen: uninsulated track, which is a track without track circuits, track with one ra'il 1,n,,':iulated and with track circuits, track with both rails insulated and with track circuits, and track with audio-fr<'.qucucv track release circuits.
12 Current return circuit and earthing
692 traction earth connection for RE <4D.
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'--------1%W/2",1
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RE <10Q
150 rn range
..,
I
Figure 12.45: Connecting poles and other components with a low earth resistance to traction earth on tracks with both rails insulated.
Basically, both rails and all tracks are used as return current conductors. In track with no track circuits, including tracks with axle counting equipment, both rails are used continously to conduct the return traction current. Both rails can be used for traction earthing. In track with one rail insulated, the other rail is used as the earth rail. This earth rail serves as a return current conductor and as traction earth. Traction earth connections are only permitted to the earth rail. The insulated rails must have a normally-open connection to an earth busbar or rail via a voltage limiter. In tracks with both rails insulated, as shown in Figure 6.47, both rails are used as return conductors for the traction current. To enable reliable operation of the relays forming part of the track circuit, the sections with both rails insulated are isolated from the adjoining track sections by insulated track joints in conjunction with reactance coil joint transformers, normally called reactance bonds. The insulating track joints in the running rails force the return traction current to flow through the reactance coil joints or via the earth rails. Figure 6.47 shows where insulated track joints are installed along a line. The individual sections of the 42 Hz or 100 Hz track circuits are separated from one another by the insulated joints in both rails of the track. The traction current flowing back to the substation passes through the reactance coil joint transformers, comprising two track reactance coils, the centre taps of which are connected. The current flows through the coils in such a way that the inductive effects cancel one another. The centre tap connections of the coils are also used as connections for traction earthing purposes. In track with both rails insulated, one of the rails is defined as being the earth rail. Any components with earthing resistances 2: 10 n may be earthed by connecting them to this rail, without any restrictions. Any components in contact with earth and which have earthing resistances between 4 n and 10 n may only be connected with the earth rail at distances up to 150 m in front of and more than 150 m behind the reactance co'i,l Joints. Within the range of 150 m to either side of the reactance coil joint, all such components must be earthed to the centre-tap connection, either via earth chokes or via voltage limiteL Any componeuts having earth resistances of less than 4 D may only be connected to the earth rail via <~arth chokes or voltage limiters, even outside of the 150 m region. Figun\ 12 4-'> illnstrates thP factors to be taken into consideration when
12.6 Alternating current traction systems _____________
693
a<= 1000m
earth wire
earth rail S-type-bond
track equipotential bond
terminal bond
a<= 1000m
a<= 1000m
Figure 12.46: FTGS-connections between the tracks and and track bonds for tracks with audio-frequency track release circuits.
connecting components to traction earth. If control and command equipment is operated using audio-frequency circuits, then usually the rail nearer to the contact line poles is used as an earth mil. Both rails are used to conduct the return current. Normally, on open main line sections, the two rails are interconnected by S-type-bonds, terminal bonds, short-circuit or equipotential bond connections at intervals of less than 1000 m, as indicated in Figure 12.46. Stype-bonds, short-circuit bonds and terminal bonds form the control and command circuit termination of the respective audio-frequency track circuits and in control and command engineering, they are called electric isolating joints. 12.6.4.3
l
Ii
I
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1
I
\
Traction system earth connections of concrete structures
The DB railway directives require that all slack steel reinforcement of reinforced concrete or pre-stressed reinforced concrete structures on or within which tracks are laid must be bonded to traction earth. This is necessary to ensure effective equipotential bonding and provide for a definite short-circuit which will cause the corresponding circuit-breaker to trip if an overhead contact line should break or accidental highvoltage contacts occur due to pantograph damage. The steel reinforcing rods and all corresponding longitudinal conductive parts are interconnected electrically and connected with the earth rail or the return conductors at intervals of not more than 100 m. The connections bet-ween the steel reinforcements embedded in the concrete are welded. However, it is not permissible to interconnect and bond ::;teel rods used for pre-stressed concrete components. Wire-binding of the bars is also permitted for special concrete structures with non-prestressecl reinforcement. Where poles, railings and noise-reduction barriers are installed on railway bridges, earth connections are made with the internal earthing electrodes of the respective structures. In structures which are longer than 100 m, additional continuous steel strips with a cross section of at least 120 mm 2 or additional continuous reinforcernent rods of at least lG mm diameter are placed in the top reinforcement layer under each track. As it is not permissible Lo conriect t:raction earth bonds directly to I lte rails of tracks with both
!
I
694
12 Current return circuit and earthing
Figure 12.47: Overhead contact line with return conductors on track in the open
rails insulated on bridges because the earth resistance of bridges is usually low, earthing busbars are installed in such cases and all components to be bonded to traction earth are connected to these busbars. The busbars are connected in turn, to the centre-taps of reactance coil joints. The DB directive 997 [12.9] contains further details on the design of traction earth systems.
12.6.5
Current return and earthing for the Madrid-Seville AC 25 kV high-speed line
Applied examples of the earthing design described above for AC systems follow: Madrid-Seville high-speed line, Magdeburg-Marienborn line, Wegberg-Wildenrath Test Center for rolling stock, Berlin-Hannover high-speed line, Cologne-Rhine/Main high-speed line, BERTS, Bangkok Elevated Road and Transit System and the system, and ERL Express Rail Link in Kuala Lumpur. Details are given for the Madrid-Seville line as an example The high-speed Iviadrid-Seville line is supplied by 50 Hz 25 kV AC [12.29]. The electrification scheme has been discussed in clause 1.4, the overhead contact line in clause 4.8.2.3. Comparisons of several alternatives resulted in utilisation of return conductors Al 240 arranged on the contact line poles. Figure 12.4 7 shows the line with the return conductors. According to c:alculations carried out during design, this solution proved to be favourable in view of line impedance and keeping rail potentials and interference at acccptabk levels. The costs are relatively low compared to other alternatives such as use of auto-transformers. The design calculations were verified by measurements during the commissioning phase.
695
12.6 Alternating current traction systems
Contact line Auxiliary generator
A
Measuring current 150 A Earthing connection
V
Measuring voltage Running rails Direction
Cordoba - - 10km km 416,213
Poles and
Figure 12.48: Measuring circuit diagram
4
Poles and return conductor ca. 300 m 600m
Figure 12.49: Return circuit arrangement and feeding points to measure the rail potential
The verification measurements required a section which represented typical conditions of the line. This situation was found in the southern part of the line between Cordoba and Seville close to the Lora del Rio substation. The length of the measuring section was set at 10 km. Boundary effects in the vicinity of the substation and at the load site are therefore negligible. The test circuit is shown in Figure 12.48. A diesel generator set in the Lora de! Rio substation provided the necessary 150 A power supply. Measurements taken along the section before tests started showed that the soil resistivity was a constant 30 nm. A potential difference will occur between tracks and distant earth when currents flow in the rail system. The maximum value at the location of vehicles or at short circuits at one end and at the return feeder connection at the other end is the rail potential. People touching the rail can bridge a part of the rail potential as touch voltage. The rail potential was measured for various fault cases as shown in Figure 12.49. These cases are: l: Current fed into one rail at the bonding point of tracks and return conductors. 2: Current fed into two rails between tlF' bonding point of tracks and return conductors. 3: Current fed into one rail between the bonding point of tracks and return conductors. 4: Short circuit at an insulator at a pole midway between two adjacent bonding points of tracks and return conductors.
-------
12 Current return circuit and earthing
696
Table 12.10: Electrical potential of the
rails to earth. Electric potential to Feeding arrangement far remote earth V/100 A 2,6 case 1 case 2 3,5 case 3 5,8 case 4 5,8 Table 12.11: lnduced voltages in unsheathed conduc-
tors along the line. Distance perpendicularly to the centre of tracks m 6
11
20 120
Measurement V/(kA/km)
Calculation V/(kA/km)
34 40 41 13
42 43 39 20
Table 12.10 lists the rail and pole potentials observed for the four cases. In case 4 a touch voltage of 5,8 V /100 A between the pole and a location 1 m distant from the side of the pole away from the track resulted from the measurements. The voltage difference between pole and rail was 7 V /100 A. In case 1 calculation and measurement yielded the same results, based on an earthing resistance of 5 n for each pole. When the earthing resistance was assumed to be 15 n per pole, the rail potential was computed to be 50 % higher, which shows the direct dependency between the earthing characteristics of the poles and the rail potential. Without return conductors, the calculations for case 1 yielded rail potentials that were some 50 % higher than for the system installed. The distribution of the return circuit is responsible for the induced longitudinal voltages in cables laid parallel with the track. The specific interference voltage related to the cable length is highest at the midpoint between substation and vehicle or substation and short-circuit location, because there the proportion of current returning through earth is at its maximum. The measurements were therefore taken in the middle of the test section. At the measuring position unsheathed cables were laid out at various distances away from the track centreline, and the induced longitudinal voltages were measured. The measured and calculated results are listed in Table 12.11. The close correlation between calculations and measurements validated the calculations as a reliable planning tool. For a section without return feeders, calculations with the same basic parameters yielded interference voltages of 70 V / (kA.km), i.e. values about 70 % higher, for an unsheathed cable 6 m away from the track centreline. In the live and return systems of electrified sections, many individual conductors are connected in paralleL Unlike DC railways, in AC railways the currents are distributed not according to the resistances alone, but according to the self and coupling
12.6 Alternating current traction systems
697
Table 12.12: Current distribution related to the total traction current. With return conductor calculation measurement
%
%
30,6 20,4 30,6 20,4
29,7 20,7 29,5 20,2
23,2 18,5
20,4 17,7 2,8 19,5 16,1 3,0 not possible
Without return conductor calculation
%
Contact line equipment
Contact wire A Catenary wire A Contact wire B Catenary wire B Return conductor system Rails A Return conductor A Cable shield A Rails B Return conductor B Cable shield B Earth
23,2 18,5 -
20,6
34,2 -
34,2 -
34,4
impedances. Near the substations and load locations, leakance between the return conductors and earth also has to be taken into account. In the middle of sufficiently long sections a constant current distribution establishes itself in the return feeder system because no current is exchanged between the return feeder system and the earth. That is why the current distribution is measured at the midpoint of the measuring section, as shown in Figure 12.49. At the measuring position current transformers were fitted in the feeding side to the contact wires, and catenary wires and to rails, to return conductors and to traction-earthed cable sheaths. Table 12.12 lists the calculated and measured results for the conductors concerned. The return current component that flows through earth cannot be measured, so only the calculated value is given. The measured values yield an earth current of about 20 %. Compared with systems without them, the return conductors reduce the return current component flowing within the soil by some 40 % and through rails by some 35 %, as can be seen from Table 12.12. This is the reason for the favourable effect on the interference voltages.
12.6.6
Concluding recornmendations
The design of the return circuit with return conductors satisfies the stipulations for personal safety even at higher powers and currents. Additional return conductors reduce interference and offer savings for earthing measures during the system design and permit simplified maintenance for both the superstructure and the overhead contact line system. The recommended measures also affect the overall construction aspects and must be defined at an early stage to allow their timely provision during the construction phase and to avoid costly retro-fitting. Figure 12.37 sumrnarizes the provisions for earthing c1trn~nt return.
12 Current return circuit and earthing
698
12.7
References
12.1 DIN EN 50122-1: Bahnanwendungen, Ortsfeste Anlagen, Schutzmaf3nahmen in Bezug auf elektrische Sicherheit und Erdung (Railway application fixed installations Part 1: Protective provisions relating to electric! safeting and earthing). December 1997. 12.2 Schneider, E.; Zachmeier, M.: Bahnri.ickstromfiihrung und Erdung bei Bahnanlagen - Teil 3: Gleichstrombahnen (Traction current return system and earthing in railway installations - Part 3: DC railways). In: Elektrische Bahnen 96 (1998), H. 4, pp. 99 to 106. 12.3 Kieflling, F.; Nefzger, P.; Kaintzyk, U.: Freileitungen (Overhead power lines, 5th edition). Springer-Verlag, Berlin Heidelberg - New York, 5. Auflage 2001 12.4 DIN VDE 0100, Part 200: Errichtung von Starkstromanlagen mit Nennspannung bis 1000 V; Begriffe. (Erection of electric power installations with nominal voltages up to 1000 V, definitions). July 1985 12.5 Ungarische Staatsbahnen: Systemauslegung bei Energieversorgung fiir 2x25 kV fi.ir Eisenbahnen (Hungarian State Railways: System design for 2xAC 25 kV power supply for railways). In: Sonderdruck MAV, 1986 (English essay). 12.6 Brohm, H.: Zur Frage der Notwendigkeit der Einbeziehung von Stahlbetonbri.ickenbauwerken i.iber mit Wechselstrom betriebenen Eisenbahnstrecken in die Schutzmaf3nahme ( Contribution to the necessity of extention of protective measures to steel concrete bridge structures across railway lines operated by AC systems). HfV Dresden, 1982, dissertation thesis. 12. 7 Kosarew, B. L: Elektrosicherheit in Fahrleitungsnetzen bei Einphasenwechselstrombahnen (Electrical safety in overhead contact line networks for single phase AC railways (Russian essay)). Verlag Transport, Moskau, 1988. 12.8 Kontcha, A.; Schmidt, P.: Elektrosicherheit im Bereich von Oberleitungen elektrischer Bahnen (Electrical safety within the overhead contact line zone of electric railways). In: Elektrische Bahnen 94(1996)10, pp. 297 to 303. 12.9 DB: German railway directive Gbr 997.0101 - Overhead contact line. 2001. 12.10 HD 637 Sl: Power Installations Exceeding l kV AC. December 1998. 12.11 IEC 60 479-1: Effects of current on human beings and livestock, Part 1: General aspects. December 1994. 12.12 DIN VDE 0100, Part 410: Errichtung von Starkstromanlagen mit Nennspannung bis 1000 V (Erection of electric power installations with nominal voltages up to 1000 V). January 1997. 12.13 EN 50 122-2: Railway applications Fixed installations; Protection against the effects of stray currents caused by d.c. traction systems. May 1999.
12. 7 References 699 =~.c.c==..c=c.:::::..---·------·---------------------------~= 12.14 VDV 500: Erdungsmal3nahmen bei Gleichstrombahnen mit Ausfiihrungsbeispielen (Earthing measures for DC railway with examples). October 1991. 12.15 VDV 501, Part 1-3: Verringerung der Korrosionsgefahr
User Guide, AYO-International,
12.22 Ka1jaki11, R. N.: Einphasenwechselstrom-Traktionsnetze (AC single phase traction network) (Russian essay). Verlag Transport, Moskau, 1987. 12.23 Markwardt, K. G.: Energieversorgung elektrischer Bahnen (Power supply of electrified lines) (Russian essay). Verlag Transport, Moskau, 1982. 12.24 Ollendort; F.: Erdstrome (Earth currents). Birkhiiuser-Verlag, Basel/Suttgart, 1969. 12.25 Eichhorn, K. F.: Stromverdriingung und Stromleitung iiber (Current displacement and current conduction through earth). In: Elektrische Bahnen 95(1997)3, pp. 74 to 81. 12.26 SdrnDer, K.-P.: Untersuchung i.iber
t
700
12 Current return circuit and earthing
12.28 DIN VDE 0141: Erdung von Starkstromanlagen mit Nennspannungen iiber l kV (Earthing of power supply installations with nominal voltages above 1 kV). July 1989. 12.29 prEN 50 162: Protection against corrosion by stray currents from DC systems. 2000. 12.30 Hampel, H.: Untersuchung von Kriterien zur Begrenzung der Streustrome aus Gleichstrombahnanlagen (Investigation of criteria to limit the stray currents caused by DC railways). HfV Dresden, 1973, dissertation thesis. 12.31 VDV 525: Schutz der Fahrstromversorgungsanlagen von Gleichstrombahnen bei Blitzeinschlag (Protection of traction current supply installations of DC railways in case of lightning}. 12.32 Moller, K.; Menter, F.; Chi, H.: Optimierung des Schutzes von Nahverkehrsbetriebseinrichtungen hinsichtlich Uberspannungen
12. 7 References
701
12.42 Kief31ing, F.; Schneider, E.: Verwendung von Bahnstromriickleitern an der Schnellfahrstrecke Madrid-Sevilla. In: Elektrische Bahnen 92(1994)4, pp. 112 to 116. 12.43 Zimmer/;, G.: Ri.ickleiterseile in Oberleitungsanlagen (Return conductors in overhead cont;act; line systems). In: Eiscnbahningenieur 45(1994)2, pp. 91 to 97. 12.44 Gruber, A.: Ri.ickstrornfiihrung auf OBB-Hochleitungsstrecken (Traction current return on Austrian Railway's high performance lines). In: Elektrische Bahnen 89(1991)11, pp. 404 to 408. 12.45 I
prntec-
12.54 I
0.: Enlung vou Ol>erleitungsanlagen (Earthing of overhead contact line installatiom,) In: Eisenbaltuiugenieur 43(1992)2, pp. 86 to 90 Z.i.mmc:r-l,
702
12 Current return circuit and earthing
13 Electric traction contact lines as err1itters of electromagnetic disturbance 13.1
Introduction
The currents and voltages of electric traction power supply systems can lead to undesirable or harmful effects in the vicinity of these systems. Figure 13.1 provides an overview of possible consequences of these effects. According to the German DIN VDE 0228 standard, the range of influence of singlephase AC 16,7 Hz and 50 Hz electric railways, with reference to long-distance telecommunications networks, is 500 m in urban areas and 2000 m in other areas. Unless the correct protective and stray current prevention provisions are installed, the range of influence of DC railway traction power systems may extend over several kilometres because of the resulting stray currents. To eliminate hazards to persons in railways, the standards E:\ 50121 and EN 50122 specify limit values for relevant parameters. Furthermore in [13.1] the limits are speci-fied for permitted interference of telecommunications systems in the vicinity of railways. The main characteristic of electric traction systems and the contact line networks, with respect to their range of influence, is the asymmetrical structure of these systems with respect to earth potential. This traction power supply system, asymmetry is characterised by the flow of return currents through the running rails, the earth parallel to Electric railway as a source of electromagnetic influence and cause of possible hazards
Hazards
Persons, animals
Interference
Operating installations
Influence on function
Examples·
- dielectric breakdown
- electric shock - shock injuries - fright
- thermal load capacity exceeded due to over currents
data transmission errors - increased probability of failures
Influence by noise - undesirable noise - interference to data transmission
- interference with electronic data processing equipment - undesirable effects on safety equipment resulting in danger to operation
Figure 13.1: Traction contact lines as source of electromagnetic influence and hazards.
704
13 Electric traction contact lines as emitters of electromagnetic disturbance
the rails and any other parallel conductors. The AC 50 Hz three-phase mains power lines, as opposed to traction power supply networks, have conductors for both directions of flow suspended from poles or multi-phase cables. They are virtually symmetrical as long as no faults occur. The overhead contact lines used to feed power to trolley buses are also symmetrical relative to earth. In electric traction systems, the current required to propel the traction units flows from the substation through the contact line system to the vehicle. In some cases, DC traction systems use the opposite polarity, so that current will flow in the opposite direction. At the position where a traction unit is at a given time and in the transition range extending to either side of it, a portion of the current will pass from the rails into the earth. This proportion depends on the coupling mechanisms between the rails and earth, as explained in detail in clause 12.3.2. The currents through the running rails, the return cables and the earth flow back to the feeding substation. The substation earthing equipment contributes to collecting the return currents from earth. Analogous considerations apply in the case of short circuits on overhead contact line. The asymmetry of the traction system and as a result, the return currents flowing through the earth, will affect technical installations in the earth e. g. installations belonging to telecommunications and information-technology systems.
13.2
Coupling mechanisms
The contact line system is a source of disturbance Q, which by means of various coupling mechanisms, can affect organisms or engineering systems in the vicinity of the railway. These systems are collectively termed potentially susceptible systems. If the wavelength A of the electromagnetic interference is considerably greater than the length l of the installation, which generally applies to traction contact line installations, then the coupling mechanisms depicted in Figure 13.2, based on a quasi-stationary condition, can be applied. If A ::; l or the surge front is extremely short, e.g. due to lightning, the interference can be described by the wave model, as has been explained in detail in [13.2). These coupling mechanisms apply, in principle, to the contact lines of both DC railways and AC railways. They will be discussed in detail in clause 13.4. In DC railways, the galvanic coupling is described by the phenomenon known as stray current, which is described in detail in chapter 12. Capacitive coupling due to higher harmonics in DC traction power networks are negligible but the inductive coupling mechanisms are not.
13.3
Interference parameters
13.3.1
Overview
In traction contact line networks, the following interfer·ence parameters are effective: the traction power network volt(/,ye, described in terms of its nominal value and the tolera.nces as shown in Tc1hlc· 1 1 as well as tlw associated electric field it
13.3 Interference parameters
705
Source of influence- natural - artificial, e. g electromagnetic processes in electric railway installations
:=>
Coupling mechanisms
~
Potentially susceptible objects and systems - e . g. information technology equipment
----i--~ ~~----R L - ________ i
,_ _ _ _
Source of interference: running rails
I iint 1
u int Galvanic coupling:
disturbed: ~ ' - - - - - cable sheath, metal pipes
U;ni= R i+L di/dt
Source of interference: _________ (...,,._ _.,..) _ _ _ _ _ _ _ _ _ overhead contact lines,
I
Mo~ - - - - - ,
- - - - - - - - - -....~-~-+---------Inductive coupling
uint- MOl-tldi/dl
uint (electromagnetic field H)
oood"cimnils disturbed: cables, conductors
-------u Source of interference: - - - - - - - - - - - , , - - - - - - - - - - - - overhead contact lines CoHL _ _ _ _ _ _ _ _ ____.,_____ _ _ _ _ _ _ _ _ _ disturbed: overhead power lines ub Capacitive coupling· uint= f(CoHu du/dt)
(electrical field E)
Figure 13.2: Main coupling mechanisms determining interference caused by electric railways.
generates, the operating current and the associated magnetic field, the short-circuit current as well as the effective duration of any short circuit which may occur, higher harmonics of the operating currents, as well as any higher-frequency electromagnetic interference fields caused by arcing between the collector strips and the contact wire or rails as well as by switching transients in the traction power supply network or traction vehicles. The circuit condition of a contact line determines the current and voltage values. The geometric position of the interference source, i.e. contact line installation relative to the interfered line or system, is also a relevant factor.
13.3.2
Operating currents and short-circuit currents
The operating current flowing through a supply section is the fundamental quantity determining the influence of other systems. For conventional railway traffic it is possible to deduce information on the variation of the operating currents along the section of line from the specific energy dcmancl P' of the line, if the exact opera ling cu:rrcnt pattern
zet±&¥
ff~
13 Electric traction contact lines as emitters of electromagnetic disturbance
706
A
8 A
associated spectrum
time function 5
I\
6
A
I:
4
1 I/ I"' 2
X
::J
:.:=
g
Q)
0
-2
\
X
/
~
()
~ C
C
Ol
co 2:
2
Ol
-4
2: -6
\j
-8
' 0
n:
2n:
Circular frequency - - - - -
0
0
50
100
150Hz200
Frequency - - - -
Figure 13.3: A full period of the magnetic flux in a transformer core and the corresponding amplitude frequency spectrum
for the line is not known. The operating currents of railway lines for general traffic and lines for high-speed traffic are discussed in detail in clause 10.4. In a traction contact line network, any earth connection will cause a short circuit. Table 11.2 can be used to calculate the short-circuit currents of single-phase AC railway systems. Further discussions on short-circuit currents in railway traction power supply networks are found in clause 11.1.1.4.
13.3.3
Higher harmonics
13.3.3.1
General
Higher harmonics of electric current and voltage frequencies may occur in AC and DC railway systems. They are caused by various mechanisms and also contribute to interference. Interference, possibly due to higher harmonics, depends above all on the power control concept used in the electric traction vehicles. When evaluating contact lines as potential sources of disturbance, it is important to consider this aspect, particularly in the case of DC traction systems.
13.3.3.2
Single-phase AC railways
In AC railway tra'--tion power supply networks, there are two so11rces of harmonics. Firstly, the power electrnnics circuits and secondly the transfarmers. Currently, pmver electronics are used mainly in traction vehicle power controls. In future, they will gain greater importance as converters in stationary traction energy supply installations. Transformers are used both in the stationary installations and in the traction vehicles. The mechanism leading to the generation of higher harmonics is different in each source. In transformers, the saturation effects in the magnetic materials lead to a magnetic flux which deviates from a true sine wave. Figure 13.3 shows the graph of a full period of the magnetic flux in a transformer core and the corresponding mnplztude-frequency
13.3 Interference parameters
- - - - - - - - " - - - - - - - -·---····-·---------------------
707
100,00 %
10,00
1
1,00
Ov
~
0,10
0,01 O
500
1000 1500 Frequency - - - - - - -
Hz
2000
Figure 13.4: Amplitude frequency spectrum, relative to the fundamental voltage Ui, of the input voltage of a power control circuit
spectrum for a stable operating state. The transformer has a marked low-pass characteristic, i.e. the amplitude of the higher harmonics decreases almost exponentially with rising frequencies. In power electronics circuits, non-sine-wave currents and voltages are the result of the switching action of the power-electronic components. Development of such power electronics, from simple rectifier controls right up to three-phase AC drive technology, has been accompanied by the development of different mathematical models describing the respective amplitude-frequency spectra for stable operating conditions (e.g. references [13.3, 13.4, 13.5, 13.6]. One example is the voltage spectrum, relative to the fundamental waveform,, shown in Figure 13.4 for a four-quadrant drive control signal. Models based on stationary conditions cannot be used to describe the interaction between the traction power supply and the traction vehicles. The movement of the vehicle along the line means that the amplitudes of the basic current and voltage waveforms vary with time and distance. The generation of even-order higher harmonics can only be explained physically in this way. Extensive studies [13.7] have shown that: - the frequency changes in the railway traction power supply network due to frequency-effective power controls used in generating equipment do not produce higher harmonics, and the amplitudes of higher harmonics in the traction contact line network vary with time and location and can be approximated section-by-section, by linear relationships. Based on these simplifications, it is possible to describe the generation of harmonics in a railway traction power supply network qualitatively, using a quasi-stationary model. In addition, it is often possible to ignore the distance relationship in comparison to the time relationship, provided the existing boundary conditions are taken into account [13.7]. A 1nodel describing the generation and propagation of higher harrnonics is illustrated by the example for a traction vehicle in Figure 13.5. \1/ith respect to the fundamental waveform, the model describing the railway traction power supply network is adequately characterised by the location of the traction vehicle and the apparent power generated or consumed. This means that only the traction vehicle voltage [itrc,1 and cmreut I 11c,I of the basic [requencv modd shmvn in the upper part of Figure i:3.5 need
13 Electric traction contact lines as emitters of electromagnetic disturbance
708
Basic frequency model
Z rr 2• 1
Example shown four-quadrant control (40C) with intermediate voltage circuit (IVC), current converter (CCV) and asynchronous traction motor (ATM)
j-: ~ j ll,,1/T, 2
U PC 1 .
~
: 4QC
IVC
CCV
ATM
r.------0-------------u transformer
filter
z,,1,v
voltage at vehicle voltage at transformer U11 voltage between Trl and Tr2 UPC: voltage at power control ltrc current at vehicle Iv transformer current Zom, overhead line impedance ZTr1 ,2 transformer impedance ZFq filter impedance
Utrc
power control, transmission and drives
higher harmonics model ZOHL,v
Figure 13.5: Structure of an electrically equivalent model of a traction vehicle for basic frequency for calculating higher harmonic generation.
ZTr2,v
calculation of the harmonics spectrum in relation to the basic frequency parameters as input values
UTr
to be taken into account. However, this does not apply to the generation of higher harmonics. As can be seen in the lower part of Figure 13.5, there are sources of higher harmonics on the vehicle itself. This means that a model adequate for calculating the higher harmonics has to include the entire electric installation of the traction vehicle. Due to the fact that different structures exist a transformer, for example, is a passive component at the basic frequency but an active component with regards to the higher harmonics it is helpful to use different models to describe the fundamental frequency behaviour and the higher harmonics analogously to the approach shown in Figure 13.5. Resonances occurring at specific positions in an AC Railway traction power supply network form a special problem related to the propagation and effect of the higher harmonic frequencies. Generally speaking, a point of resonance occurs wherever the effective network reactance for a defined frequency is zero. Even if a source of electromagnetic interferences is located at this position, only those cases in which the active reactance of the network does not attenuate noticeable resonance effects are of practical relevance. Moving and temporary resonance points occur in the network due to the vehicles running along lines, making them difficult to localise. As a result, preventative measures are possible to a limited extent only. One method of localising parts of the network more susceptible to the occurrence of points ofresonance, is to carry out a point-of-resonance analysis as described in [13. 7] on the basis of the network model shown in Figure 13.6. The most simple example chosen is a single-track line with one-sided feeding by a single-phase synchronous generator via a transformer. In Figure 13.6, a traction vehicle is travelling along the line. This vehicle is described by the higher-harmonics model according to Figure 13.5. Furthermore, idealized boundary conditions were assumed to apply. To simplify calculations, it was assumed that the contact wire's parameters per unit length did not vary with frequency Point-of-resonance o:nalys'is descrihc~d by [13.7] is based on a superposition principle. In
13.3 Interference parameters
709 loHL
Figure 13.6: Network model used for point-of-resonance analysis.
source 2 source 3 source 1 Gentransformer ~ratio~ converter substation
traction contact line section 1
traction contact line
transformer traction vehicle
1
'----L
f=1187,0Hz x 80 kQ
section 2
I/pc voltage at power control I01-1L current on overhead line Zss substation impedance ZTr transformer impedance Z1rq coupling impedance Z1r1 overhead line impedance Zcen generation impedance
=10km
l
trc _ _
. : substation transformerI 60 ,_ _,_,,_---,source II : traction vehicle transformer source Ill · traction vehicle power controls f=15ci43Hi 40 source Ill 20
l Ql 0 C
0
{=1505,8 Hz {=1188,9 Hz
cu
1;j
-20
~
~
ro>
-40
5
Jr -60 -80
f =1190,8 Hz 0
20
40 60 80 100 120 140 k.0160 Equivalent resistance - - - - -
Figure 13. 7: Substitute network impedance at any point of the network, as a function of the frequency, plotted in complex quantity co-ordinates for all sources of electromagnetic influence shown in Figure 13.6.
other words, the entire network is related back to the basic current circuit for each individual source of electromagnetic influence and is represented by the network impedance Ze. This makes it possible to study the effect of each interference source individually, whereas measurements can only determine the superimposed effect of all interference sources. The first step is to determine the basic relationship bet,-veen network impedance and frequency for all three interference sources shown in Figure 13.6 and plot these on a complex quantity co-ordinate system. This basic graph, shown in Figure 13.7 is
source I
· substation traa~n2s::;fo~rm~erc.----i-----J
15 5 10 20 25 km 30 Vehicle position x trc - - - - -
Figure 13.8: Resonance frequency of the three sources of electromagnetic influence shown in Figure 13.6
13 Eledric traction _______________ _ contactlines as emitters of electromag·.rntic disturbance
710 .:..:::__
applicable in principle for any vehicle location. Figure 13.7 shows tlrnt the first point of resonance occurs where the network impedance characteristic changes from ohmicinductive to ohmic-capacitive. However, resonances are effectively attenuated here by a high resistance value. Resonance effects are to be expected only at the second point of resonance where the network impedance characteristic changes from ohmic-capacitive to ohmic-inductive. Figure 13.8 shows the graphs of the resonance frequencies at the point of resonance as functions of the vehicle location. By comparing the frequency ranges shown in Figure 13.3 to those shown in Figure 13.8, it is seen clearly that no resonance effects of electromagnetic infiuences caused by the transformer are to be expected. In contrast, the interferences clue to the traction vehicle power controls, which typically generate higher harmonics with the frequency range shown in Figure 13.4, coincide with the resonance frequency range of this source of electromagnetic infiuence as shown in Figure 13.8. However, it is not yet possible to draw conclusions on the magnitude of the higher harmonic frequency currents that can be expected, since the behaviour of the interference source depends on the parameters of the basic frequency. From the frequencies shown in Figure 13.7, it can be seen that it is partially necessary to select frequency steps of less than 1 Hz to be able to determine and depict the frequency-dependence of the substituted network impedance in detail. When investigating extended networks and also when the frequency-dependence of some model parameters, such as the skin effect are being taken into account, it will be necessary to achieve some form of automatic weighting and evaluation of the results to be able to process the correspondingly large volume of information at all. A suitable point-ofresonance assessment system [13.7) provides a means of achieving this. 13.3.3.3
Direct-current railways
Modern DC traction vehicles are equipped with asynchronous traction motors or DC motors controlled by pulse-control circuits. In both cases, power electronics circuits are used to connect the traction power supply network to the vehicle's traction motors. The pulse control circuit depicted in Figure 13.9 can be used to describe its effect as a source of electromagnetic infiuence. Figure 13.9 shows a moving DC pulse-control circuit connected to the contact line. The traction motor is supplied by current impulses, the duration and/ or frequency of which can be controlled by the circuit. The source of the energy has a specific inductivity due to the contact line installation and the substation. To compensate this and retain a low-inductance energy source, the buffer capacitor Cp is required. An additional buffer inductance LP must be inserted between the contact line and tlw control circuits in order to keep resonance effects and overvoltages to a minimum. Detailed discussions on these smm.·es of electromagnetic influence are found in references [13.8) and [13.9]. Zimmer, in [13.8), concluded that in the case of pulse-controlled DC railways considerably less interfc'.renc:e can be expected than in thynstor-contrnlled traction vehicles in AC railway syst<~rns.
13A Interference clue to single-phase AC railways
--
LoHL= LOHL
X
711
contact wire
1trc
I
I
U1,c
IM
13.9: Mobile DC power control circuit connected to a contact line. IM mean motor cunent Uo11L overhead line voltage Up buffer voltage ss substation Lam contact line impedance Lp buffer impedance traction voltage U1,c traction current ftrT motor current h,1 buffer capacitance Cp controlled current Is width of current surge tF
Figure
track
controlled current
ls I
JM
voltage across buffer capacitor
Up
Period of time - - -
13.4
Interference due to single-phase AC railways
13.4.1
Introduction
In this section, the basic problems of influence and interference due to the traction power contact lines of single-phase AC railways will be described. A single-phase AC railway can be represented by a system of two inductively coupled cond·uctor loops. The real situation can best be represented by the coupling between the loops contact-lineearth and track-earth. Basic methods of calculating the main parameters are discussed in chapter 3. The patterns of the currents in the contact line, the track and in the earth are shown in Figure 12.8. Since the track normally extends beyond the point where the load is connected, currents will flow from the track to earth, even outside of the section between the substation and the position of a traction ,ehide.
13.4.2
Galvanic interference
Technical equipment and lines in the vicinity of electric rail ways can be connected to a part of the return current path by galvanic coupling via the cart h and/ or direct metallic contact, as can be seen in Figure 13.2. The circuits emitting and receiving interference can use the same conductor paths. In addition to the induced ctments f-iowing in underground metal cable sheaths and pipes running in parallel to electric railway lines, a c:unT11t will flow through these illstallations clue to galvanic: coupling with the return c:11n<'t1ts The current quantity
13 Electric traction contact lines as emitters of electromagnetic disturbance
712
telecommunication cable substation
Uab
line section and station feeders
Figure 13.10: Increase of potential due to galvanic coupling of return currents. Ii< short- circuit current Uab voltage due to galvanic coupling RE earth electrode resistance
of this galvanically coupled component will depend on the contact resistance between earth and the respective installation. The electric potential rise of telecommunication cables, which may be caused in the vicinity of the substation, is particularly troublesome. This effect can be explained using the circuit diagram shown in Figure 13.10 for an armoured telecommunication cable. The cable sheath is connected to the reference earth potential at the substation. If a short-circuit current h flows through the substation's earthing system, then the factor k defined in (12.1) can be used to calculate the galvanically-coupled voltage that can be measured and is equal to (13.1) In this equation, RE is the earth electrode resistance of the substation, typical values being in the range of 0,05 to 0,3 n. To eliminate hazards to persons and installations, all metal parts in the vicinity of contact lines, and particularly within the overhead contact line zone shown in Figure 2.16, has to be potential-bonded to the earthing system. In AC line systems, this is done using the traction earthing system.
13.4.3
Inductive interference
Inductive interference is caused by the current flowing in the contact line-return line loop. The magnetic field generated by this current acts on metal installations and cables in the vicinity of the railway line. The alternating magnetic field generated by the operating current of AC railway systems as well as by the higher harmonics occurring in both AC and DC systems, can induce voltages in the affected installations and cables, potentially causing damage or interferences. Inductive interference to conductors in the vicinity of traction contact lines can be described by the inductive coupling between two conductor-earth circuits located in parallel to one another. As shown in Figure 13.11, it is assumed that the conductor subjected to interference is situated in a railway line section where the transitional effects in the interference source system contact line-track-earth are negligible. In Figure 13.11 it can be seen that a current I flowing in the contact line will induce a length-dependent longitudinal voltage U{ in the affected cable. Assuming that the length l of the affected cable is less than that of the contact line emitting the interference, the induced longitudi-11,al voltage per ·11,n1,t length is described by the equation:
U( = 2 7rf l\ibm, ·I· r
(13.2)
13.4 Interference due to single-phase AC railways
713
-1
l x =effective interfering current
u 1 =induced longitudinal voltage
M'
per unit length
z
M' =mutual inductance per unit length Z =effective impedance at location of load or short circuit / =length over which the interference acts
R', L', G', C', are characteristic line parameters of the system subject to interierence I
I
x=O
x=I
Z 1 und Z are the terminating impedances 2
of the line subject to interference
i
element of line subject to interference, length dx
R'dx
u
L'dx
Cdx
G'dx
u+du
Figure 13.11: Inductive interference coupling mechanism.
In this equation, MbHL is the mutual inductance per unit length of the conductorearth current loops of the electric traction system and the system subjected to the interference. Furthermore, r < l is a reduction coefficient describing the effect of the currents flowing in rails, cable armouring, earth wires etc., which have a cancellation effect nearly in opposite-phase. The induced longitudinal voltage per unit length is directly proportional to the frequency f of the traction power supply. To determine the local magnitudes of induced voltages and currents, the circuits shown in Figure 13.11 can be used to formulate differential equations which are also mentioned as telegraph equations in related references [13.10]. Their general solutions are:
u(x)
-Zw (A exp('y x)
B exp(-'Y x))
i(x)
U{/Z' + A exp(,-yx)
+B
(13.3)
exp(-,x)
In these equations, Zw is the surge impedance and I is the propagation parameter of the metal line affected by interference. Zw and 'Y of the affected line are calculated according to the equations (12.16) and (12.17). Constants A and Bare functions of the reflections in the interfered line and thus depend on its connection status. The connection status describes how the ends of the cable are terminated. Figure 13.12 shows the connection status typical of cables frequently located in the vicinity of railways. For electric conductors with a matched termination, e.g. metal pipes or rails which extend beyond the range of influence and assuming that the induced longitudinal \ oltage per unit length, U{, is constant, the following applies: '/1,
'/,
-U((l - exp(-,l))/(21·) (U(/Z')(1 - exp(-0,5 1·/))
-----------
(13.4)
-------------------------
13 Electric traction contact _!i_nes as emitters of electromagnetic disturbance
71-1
2
2
a) 1a) open circuit
I X
:::, QJ
Ol ~
0
>
c)
I I I I I I I I I I I
=
I
k:_--
N
'..._
..._
/
c) earthed at both ends
I b) earthed at I one end I
I I I I I
b)
2
I I I I I I I I I
I I I I I I I I I I
I _.,
I=
I I I I I I I I I -----1
-
I
....;< I
c
~
Distance - - - - - -
:5
0
- - insulated from earth (individual strand in a cable, overhead line)
- - - · installed in contact with earth (cable sheath, metal pipe)
Figure 13.12: Effect of the connection status on longitudinal voltage induced in a cable subject to interference and the currents due to these voltages. a) connection status; b) induced longitudinal voltage; c) current
If both ends of insulated conductors of a cable subject to interference are open, the solution of this equation for the conductor-to-earth voltage is: (13.5) This connection status is shown in Figure 13.12 a. In the case of affected conductors connected to earth at the far end, the solution of the equation for the voltage known as the longitudinal voltage is: U'I · l
(13.6)
This connection status, which is the most important one in railway engineering practice, is depicted in Figure 13.12 b. The longitudinal voltage is directly proportional to the longitudinal voltage per unit length and the length 1, also known as the effective length of the affected section. The absolute value of this length-related quantity can be used for calculations in practice. The voltage in an affected cable earthed at one end is:
U(
2 n-J · .Mbru, · I · r · w
(13.7)
In this equation, w is the probability factor of a short-circuit current during transient interferences. It allows for worst-case conditions being used as a basis of the calculations and that the simultaneous occurrence of all unfavourable circumstances and events is extremely unlikely. On the basis of the studies described in [13.11] and [13.12], the values 0,55 to 0,70 can be assumed to apply for w. The ·reduction coefficient is given by (13 8)
13A}nterference due to single-phase AC railways
715
where track reduction coefficient, rE reduction coefiicient of return wires, rI< reduction coefficient of the cable sheath of the affected cable, r1, reduction coefficient due to other earthed conductors a.nd components within the interference range. If reduction coefficient measurements are not available, the application of the following values is recommended: Tc; 0,2 near substations for double-track lines, 0,45 further than 2 km from substation for double-track lines, 0,55 further than 2 km from substation for single-track lines, 0,55 to 0,7 if Al 240 mm 2 return wires are installed, depending on TE the position relative to the contact line system, Tl( 0,1 to 0,5 to telecommunications cables, depending on the cable design as specified by the manufacturers, 0,7 to 0,8 in densely built-up areas (according to [13.13]), TL 0,9 to 1,0 in rural areas (according to [13.13]), For the relative mutual fr1,ductance per unit length of two conductor-earth loops, ]\lloHL, [13.14] derived the following equation in which a is the distance between the loops and the relative permeability of the atmosphere and earth is assumed to be 1, re;
l\libHL
{ 1+ 2· ln
[L100 / (aJf /PE)] - j /2} · 10- 4 l:n
(13.9)
7f
For practical purposes in railway engineering, the following numerical formula for the value of this mutual inductance per unit length is adequate:
.MbHL = 0,1
+ 0,2 · ln [400 /
(a/f /PE)] .
.Mb1-IL
0,
f
mH/km
m
Hz
PE n-m
(13.10)
Equation (13.10) corresponds to equation (10.21), i.e. l\lI0HL = L~IIL· In this case, µ 0 has the value 41r · 10- 4 (Vs)/(A km). Figure 13.13 shows approximate values for the mutual inductance per unit length for frequencies of 16,7 Hz and 50 Hz for typical earth resistivities. In practice, the longitudinal voltages per unit length in conductors in the immediate vicinity, i.e. at a distance of roughly four to eight metres from and parallel to the railway center line, are of particular relevance. To study these, the induced longitudinal voltages per unit length have been measured and calcula.ted as functions of the distance from the track center line. The results shown in Figure 13.14 apply for specific earth resistivities commonly found in the immediate vicinity of the tra.ck: 27 nm which is equivalent to 3,7 · 10-,, S/cm. The longitudinal voltages per unit length shown in these graphs are referenced to an inducing current of 1 kA.
Exan1ple:
Check whether an mtprotected cable without reductio11 coefficient can be used for a 2,9 km com1cction between the signal box and the dectrouics control cabinet of an audio frequency track release circuit ir the traction current is 1:rno A. "flt<~ line in question is
13 Electric traction contact lines as emitters of electromagnetic disturbance
716
1,1
mH km 0,9 0,8 0,7
_ii
0,6
- - pE=27 n·m - - · p =2900-m E
'' ' ' '' ''
"" "
', ' ' ' I"-" ' ' '
' ''' '' ' ''
" ~"
""""~""
~
g 0,5 cu
u
~ 0,4
:::,
:5 2 0,2
I
',so Hz
''
~
50 Hz 16,7 Hz
0,1 10
80 V kA-km
-,!
' ' ' ' ... ' ' , 16,7 Hz ' I '
""' ~""
~
ro o,3
0
~
20 50 100 200 Distance a _ ____,_
m
-
500
Figure 13.13: Approximate values for mutual inductance per unit length as a function of the distance between affected conductor and traction contact line.
- - measured values for 27!2m~3,7·10·4 s/cm - - · calculated values for 27!2-m - - measured values for 11 nm
'
60
-
::i ~ 40 ()
u
:::,
u
.S
~ :iii~
20
-~
&~
0
2
3
5
8 101
2 3 Distance a - - - -
5
8 102
m
2
Figure 13.14: Longitudinal voltages per unit length in a cable running in parallel to the track induced by traction currents at a frequency of 16,7 Hz.
a double-track line operated with 16,7 Hz single-phase AC, equipped with return conductors. It is assumed that: re= 0,45, 7'E = 0,6, 7'L = 0,8, a= 5 m and PE= 100 Dm. By interpolating the values shown in Figure 13.13, the coupling inductance per unit length between contact line and the affected cable can be found to 1,15 mH/km. If equation (13.10) is applied, the calculated value is 1,16 mH/km. Using (13.5) and taking into account (13.8), the interference is calculated to reach a voltage of 49,5 V. This value is lower than the permitted maximum limits according to Figure 12.1. Therefore, it is possible to use an unprotected cable without a reduction coefficient. Furthermore, check whether the permitted values defined for the influences due to a transient short circuit of up to 0,5 s duration are not exceeded in this cable. CCITT standards specify
13.4 Interference due to single-phase AC railways
717
4
kV 8 0HL Urn-IL
cw
I'
L
::::)-'2
CoHL
OJ
0)
~
g1
5
10
15
m
20
Mutual distance aOHL _ ____,,_
Figure 13.15: Capacitive interference on a ca- Figure 13.16: Voltage generated in an overhead line due to influence by a contact ble L due to a contact line CW line voltage of 15 kV, as a function of the distance aoHL between the parallel sections and for various heights aH of the affected conductor above ground.
a permissible value of 430 V for contact line short-circuit conditions, German standards state a limit of 500 V (13.2]. For a calculated maximum expected short-circuit current of 30 kA and a probability factor w of 0,6, it can be determined that the induced voltage would be 236 V, which only acts for a period of 0,06 sat the most.
13.4.4
Capacitive interference
The electric field generated by the live parts of contact line installations of AC railways can electrically charge conductors and system components located in the interference range of the contact lines by influence effects. However, this charge only leads to measurable voltages if the respective conductors are insulated relative to earth. Underground cables or underground systems are not subject to capacitive interference. By applying the potential divider rule to the circuit shown in Figure 13.15, the absolute value of the voltage UL on a conductor running parallel to the contact line can be expressed as: UL= Ucw C~r-rd(Cf,E
+ C~rJ
(13.11)
CLE is calculated according to equation (10.30). Reference [13.15] explains that the capacitance per unit length C~I-IL can be approximated using the following numerical formula: -,, C OHL
54ar-r
144 + a,
2
+ 0}1
C'OHL " nF/km
.
(13.12) m
··---------------
i
I
13 Electric traction contact_lines as emitters of electromagnetic disturbance
718
For double-track lines, the expected capacitance per unit length is approximately 1,5 times the value obtained by equation (13.12). The in_fiuence voltage, which is independent of the length of the sections of a conductor running parallel to a 15 kV overhead contact line, is shown in Figure 13.16. One conclusion that can be drawn from this graph is that unearthed lines and metal objects which are as low as 1 m above ground level and also near to the track, may achieve voltages of up to 600 V. The potential hazards due to capacitive influence include, the danger of electric shock to humans touching the high-tension metal surfaces. Danger to human life as a result of the charging current, which is calculated as le= w c~HL Ucw l
(13.13)
is not even to be expected for a section of insulated cable of 2 km length running in parallel to and at a distance of 10 m from an overhead contact line. In [13.15], a corresponding charging current of 5,5 mA was calculated. This also applies to telecommunication cables in a cable duct along the railway line. Since CbHL is extremely low for these cables, le cannot reach dangerous values.
13.5
Electric and magnetic fields in the vicinity of traction contact lines
13.5.1
Basics
For electric energy to be transmitted to traction vehicles, a potential difference equal to the operating voltage has to be maintained between the contact line and the reference potential i.e. earth, and a current has to flow through the contact line. This means that an electric .field, E, which exists as long as the contact line is not switched off, and - a magnetic .field, H, which varies with time and location, are induced all around the contact line. With reference to media reports on so-called electrosmog, the question of what adverse effects the electric and magnetic fields can have on human beings in the vicinity of railway installations is raised frequently.
13.5.2
Effects of electro1nagnetic fields on human beings
The permissible values of electric field and magnetic .field strengths in high-voltage installations accessible to the general public were set out in legislation in several countries. The German Federal Minister of the Environment (BMU) in [13.16] taking into account the IRPA [13.17] recommendations. Since the magnetic induction, i.e. the flux density B is easier to measure, it is often taken as a reference value instead of the magnetic .field strength H. In a homogeneous magnetic field, B
H ·/Lo·//.,
13.5 Electric ancl magneticficlds in the vicinity of traction contact lines
719
The unit of magnetic flux density B is the Tesla, which is defined as 1 T 1 V s/m 2 . Using the values 1 11,T = 10- 5 T and with µ 0 according to (10.9) as well as 11, 1 1, the following equivalence can be used to convert the parameters describing a homogeneous magnetic field: 1 A/m is equivalent to 1,256 1/T and 1 µTis equivalent to 0,7962 A/m. (13.15) The facts concerning the f~/fects of electric and magnetic fields on human beings are described briefly, below. The following information is based on research described in [13.18]. On the surface of the body, the electric field creates a charge which in turn can lead to currents passing through the body. Large numbers of experimental studies ha\·e shown that an electric field strength of 1 kV /m will lead to a current of approximately 0,015 mA in the human body. In this case, the corresponding current densities are between 0,2 and 0,3 mA/m 2 . The currents resulting from the electric field are neither a function of the conductivity of the body nor of the person's size. As opposed to this, the magnetic field induces body currents which are functions of both the person's size and the body's conductivity. An induction of 1 µ,Tat a frequency of 50 Hz will lead to a current density of roughly 0,01 mA/m 2 . It has also been proved that current densities up to 1 mA/m 2 cause no discernible effects on the human body. Current densities of 10 mA/m 2 and above can lead to a flickering sensation in the eyes, and current densities of 100 mA/m 2 lead to nerve and muscle stimulation. The danger threshold is 100 mA/m 2 . The value above which real injury is probable is in the region of 1 A/m 2 . The average cross-section area of the human body is between 0,06 and 0,07 m 2 • Table 13.1 summarizes the above statements for the typical railway traction energy frequencies of 16, 7 Hz and 50 Hz. The reference values stated in various sources are shown in Table 13.2. Table 13.3 shows electric field strength and induction values measured in railway environments. Figure 13.17 shows the characteristic graph of the magnetic field strength of an electric railway line as a function of the distance from the centerline of a double-track line. The magnetic field strength measurement values shown [13.20] are given with reference to overhead contact line currents of 1 kA per track. After assessing the contents of Tables 13.1 to 13.3, it can be concluded that not even the extremely stringent precaution limits set by the BMC for both electric fields and magnetic fields are exceeded in rail way applications. Therefore, electric or electromagnetic fields caused by railway operating equipment pose no danger to human beings. Potential hazards due to induced longitudinal voltages and track-to-earth potential differences have been discussed in clause 13.4.3 and in chapter 12
13.5.3
Effect of fields on equipment
13.5.3.1
Effects in general
The electric mid clectro111al-',m'tic fields also affect apparatus aud installations in the viri11itv of rnil\\'a\'S Pnsous witl1 implanted cardiac pacemakers or other similar im-
13 Electric traction contact lines as emitters of electromagnetic disturbance
720
Table 13.1: Effect of low-frequency electric and magnetic fields on the human organism according to results given in [13.19]. Current density threshold values mA/m 2 1 10
100
1000
Consequences if threshold is exceeded
Thresholds occur at
Current m body
f E
B
E
µT
0,07
100
kV /m 12 to 15
B 1LT 300
0,7
40 to 50
1000
120 to 150
3000
1200 to 1500
30000
Muscle and nerve stimulation (potentially dangerous) Injury (possibly lethal, ventricular fibrillation)
7
400 to 500
10000
70
4000 to 5000
100000
Table 13.2: Permissible maximum values of electric and magnetic fields in standard technical frequency ranges, up-to-date July 1997. Exposure range
IRPA and WHO recommendations 16,7 Hz B
E
kV/m
Range 1 1 h/d 2 h/d permanently Range 2 permanently several hours per day Range 1: Range 2:
IRPA: 1)
15 30
µT
300 3000
= 16,7 Hz
kV/m 4 to 5
mA Measurable effects Stimulation (flicker felt in eyes)
f
= 50 Hz
50 Hz
E
B
kV/m
µT
30 10
4000 400
5 15
100 1000
German directive [13.16] in force as of 01.1997 50 Hz 16,7 Hz B E B E kV/m
µT
kV/m
µT
10 20
300 600
5 10
100 200
1)
1)
1)
I)
controlled areas, generally accessible but where it is ensured that the exposure is of short duration . all areas in which short-period exposure cannot be normally expected, e.g. residential and office buildings, sports, entertainment and recreation facilities International Radiation Protection Association Short transient peaks, total exposure time o[ up to 1,2 h pet day.
13.5 Electric and magnetic fields in the vicinity of traction contact lines
721
Table 13.3: Electric and magnetic field strengths measured in the vicinity of electric railway systems. Where measured E B Traction power supply
µT
kV/m
Edge of station platform, 1 m above rails, 0,07 100 25 7 m away from track centerline 0,05 Edge of station platform, 1 m above rails, 0,3 100 DC 3000 V 0,2 25 7 m away from track centerline Edge of station platform, I m above rails, 1,6 AC 16,7 Hz 100 25 15 kV 7 m away from track centerline 1,1 AC 50 Hz Edge of station platform, I m above rails, 2,7 100 25 25 kV 7 m away from track centerline 1,8 Comments: If return conductors are installed, the magnetic field in the close range is reduced by up to a third and in the 4 m range by up to half. The magnetic field strengths are measured for a current of 1000 A flowing in each overhead contact line.
600 V
DC
position of individual conductors
140 A
l I
~
20
m
(j)
::,
120
D
C
0
~
0
0
E ~
I
.!],
60
I I
I
D
a3
I
0
'a; C
40
I
Ol
cu
2
v"
20
-
--
0 -15
_j
/
\
C
0
C
\; 0
\
c0
\'
0 0
C :3
~-~
0
-~
I----
/"i',
\I
V
~' 0 cu
I
0
I .!],
80
.;=
c"'0
I
3
100
::,
Ol
--u-+-+-+---1--+---+--+---<
(])
C
g 0
(])
I
V
c.--
-
I- -
-13
-11
-9
-7
-5
-3
-1
0
1
3
5
7
9
11
13 m 15
Distance from system center line - - - -
Figure 13.17: Magnetic field strength, 1 m above rail head, comparison of measured and calculated values, It.re = 2 x 1000 A [13.20]. without return conductor, calculated with return conductor, measured with return conductor, calculated
722
13 Electric traction contact lines as emitters of electromagnetic disturbance
~'..-------------
plants may be affected adversely and operation of information-technology eq11,ipment, especially VDUs, can be impaired. In addition, electric traction systems emit radio frequency interference that may reach intensities that disturb equipment in the vicinity of the railway.
13.5.3.2
·I
Persons with implanted cardiac pacemakers
According to German Standard DIN VDE 0750 the peak value of the eqm:valent .fiux density in the frequency range from 1 Hz to 30 kHz has to be calculated as follows: A
B
u
= 188 · _IT ' f
At frequencies up to 1 kHz a peak-to-peak voltage UPP of 2 m V is permissible. This gives a substitute magnetic flux density of 226 p,T for a frequency of 16,7 Hz. In practice, however, because of the inhomogeneity of the magnetic fields and the lower susceptibility of the signal circuits, the probability of interference to cardiac pacemakers due to magnetic flux densities of less than 200 p,T is extremely low, even at a frequency of 50 Hz. In this context, [13.21] reports that it was not possible to detect any influences to implanted cardiac pacemakers by static (direct-current) magnetic field strengths of up to 500 µT. This is back by the fact that adverse effects to persons with implanted cardiac pacemakers are unknown.
13.5.3.3
Information technology and electronic data processing equipment
The magnetic fields in the vicinity of railway installations can cause interference to cathode-ray t1tbe monitors. Other susceptible equipment may also experience influences. The paper [13.22], for example, reports interference to an electron microscope due to the power cable of DC railway system located at a distance of 70 m. When a current of 1400 A flowed through this cable, the electron microscope was exposed to a 4 {IT magnetic field, making it impossible to use the microscope. Generally applicable standards, stating permissible values of field strengths for IT and EDP equipment, are being drawn up. Paper [13.23] reports on measurements and determined the following values as limits of unimpaired operation: Computer monitors: Tolerable value depends on the monitor design. The susceptibility of the monitor increases ,vith screen size. Interference is noticeable from values of just below 2 flT and higher. Television set cathode-ray tubes: Large screens show interference effects for 50 Hz fields of strength 1 1LT and higher, LIH\ limits for static (DC) fields are beh,·een 10 and 30 µT.
13.5.3.4
Electric railways as sources of radio-frequency interference
Electric railways may emit rrulio-f1err1w·11.1:'.IJ ·1:nl.e·1Jerence (RIV). The standard EN 50121 was drawn up to deal with this issue Tal>l<~ 13 4 shows a summary of the co!ltents of
&dil&l!lll
!3.5 Electric and magnetic fields in thevicinity oftractioncontact. lines__________ _____
723
Table 13.4: Summary of EN 50 121 according t.o reference [13.24] EN 50121
Railway Applicatio1rn-electrornagnetic compatibility
EN 50121-1
General
-
General overview of all parts of the standard. Definition of the performance criteria of EN 50 082-2 with respect to immunity to interference. Description of railway systems and the associated sources of influences and coupling mechanisms. EMV management when railway line network and rolling stock are operated by different companies.
EN 50121-2
Emission of the whole railway system to the outside world
Methods of measuring radio frequency interference clue to passing trains (peak detection) - Limits for radio frequency interference in the range of 9 kHz to 1 GHz Description of fields in the vicinity of railways, mapping of electric, magnetic and electromagnetic fields by means of measurements or calculations. EN 50121-3-1
-
Mains pollution, (limits to be specified), influence current measurements. Radio frequency interference, measurement and limit values Immunity to interference, not of rolling stock, but of equipment to be installed on rolling stock.
EN 50121-3-2 -
-
-
Signalling and telecommunication apparatus
Influence emission, testing and limits for various interfaces. Immunity to interference, testing and limits for various interfaces.
EN 50121-5
-
Rolling stock Rolling stock apparatus
Influence emission, testing and limits for various interfaces. Immunity to interference, testing and limits for various interfaces.
EN 50121-4 -
Rolling stock Train and complete vehicle
Fixed power supply installations
Radio frequency interference emissions by substations, contact lines and feeder lines Immunity requirements applicable to equipment.
the six parts of this standard. Accordingly, the main causes of RIV due to electric railway systems are: spark discharges in the traction contact line network, e.g. across droppers that are inadequate for the currents, loss of contact between the contact wire and the pantograph collector st.rip, with subsequent. arcing, corrm1,'atation prou:sses in electric traction vehicles, switchzng and rnnlrnl lra11.,1,e'11,ls i11 rlectric railway switcltp,ear awl v<~hides.
13 Elect;ric traction contact lines as emitters of electromagnetic disturbance
724
------------
120 120 dBµV/m dBµNm 100 - J . . - - - - - - - + - - - - - - - - - - i - - - - - - t - - - - - 2 5 k v - - - - ; - - - - - - + 100 90 -1 - - - - - - - t - - - - - - - + - - - - 1 5 kV, 3 kV, 1500V--=:-=----==--I------+ 90 750V 80 80 70 70 60
60
u
50
50
u
S2
40
40
-=u
~ a5 C
Ol
cu 2;
a5
30 C 0Q) 25 kV 20 uJ 20 -1--------+----------1-----_:::,,k--=,,___,_,.,::,,,. 15 kV, 3 kV, 1500V 10 - 1 - - - - - - - - + - - - - - - - l - - - - - - + - - - ~ 7 5 0 V - 1 - - - - - - - - - 1- 10 0 0 0, 1 10 0 bw1
30
H
E
Frequency f - - - - -
Figure 13.18: Permissible maximum values of RF influence levels according to EN 50 1212:2000.
The graphs in Figure 13.18, showing the permissible maximum values of RF influence levels for frequencies between 7 kHz and 1 GHz, have been taken from standard EN 50121-2. The stepped characteristic results from the different methods of measurement used. For instance, between 150 kHz and 30 MHz, the level is measured as a magnetic field with the aid of a coil antenna, and at frequencies above 30 MHz the electric field strength is measured using a dipole antenna. The measurements are carried out using the 10 m peak detection method.
13.6
Conclusions
A main characteristic of electric railways is the fact that electric traction currents return to the substation via the running rails in contact with earth. For this reason, a portion of the return current to the respective feed substation will also flow through earth. In single-phase AC railway systems, inductive 'coupling creates a line-to-earth current loop in addition to the galvanic coupling of the rails to earth. This characteristic of electric railway traction systems, also termed unbalance or asymmetry, coincides with the widespread and large area covered and in which technical and biological systems rnay be affected. From the deductions made and the discussions set forth in this chapter, it can be concluded that the elect:ric and elPctromagnetic .fields in the vicinity of railways: do not lead to any organic stimulation and definitely do not pose any danger to human beings, do not endanger persons with implanted cardiac pacemakers, but can disturb the performa11c<~ of i11forrnatio11 technology equipment and other highly susceptible devices. T'he cause of such i11fluenccs is above all, magnetic field strengths in the region of l to :30 11T.
·l
13. 7 References
Corrosion of underground metal parts induced by stray currents is a possible adverse affect of DC railway systems on other systems located underground. Standard EN 50 1222 describes protective measures to eliminate the effects of stray currents from DC traction power supply systems (see clause 12.5.3). These measures can prevent corrosion damage being caused by stray currents. Well organized co-operation of the operators of installations with underground components, cables and pipelines with the operator of the DC railway is of vital importance for the success of such efforts. In single-phase AC railway traction systems, the capacitive interference must be counteracted by earthing all metal parts that might otherwise become electrically charged. Galvanic interference in the vicinity of single-phase AC railway traction systems can be prevented by installing insulating joints in potentially susceptible conductive systems within the range of influence, e.g. in cable sheaths and metal pipes which lead into the substations. The inductive interference must be taken into account when designing and operating technical systems and devices. The inductive interference of the fundamental frequency can endanger and interfere with equipment and installations in the vicinity of railway traction power installations. The higher harmonics occurring in railway traction networks are sources of interference, especially in telecommunications systems. As no binding international limits have yet been defined for voltages liable to cause danger, it is advisable to consult the latest agreements of the arbitration bodies for influence and interference issues or comparable national organisations. The objective of the arbitration institution, incorporated in Germany since 1939 and supported by the railway company DB, the telephone company Deutsche Telekom and the umbrella organization of German electric power utilities, is to settle interference disputes and issues by mutual agreement on the basis of equality of all concerned.
13.7
References
· 13.l DIN VDE -0228, Part 1: MaBnahmen bei Beeinflussung von Fernmeldeanlagen ste11crbarer Schaltuug (Irnpact of the smoothing and co1111uutatiug n)actattcl:S 011 Lite network behaviour of multiple sequence-controlled converters in single phase half~controlled connection). Eidgcuc)ssische Technisclw Hochschule Ziirich, 197:L disscrt.atiou thesis.
726
13 Electric tr,1~:tiou contact. lines as_CI!~it~~ern of electrom~1gnetic disturbance
13.5 Janssen, R.: On-line-Optimierung des Net:;;verhaltens von Bahnstromrichtern mit sekt,orsteuerbarem Einspeisestromrichter (On-line optimization of the network behaviour of traction power converters with sectorial controllable infeed converter). RheinischWestfalische Technische Hochschulc Aachen, 1983, dissertation thesis. 13.6 Klein, H.-J.: Entstehung, Ausbreitung und Wirkung der Storstrome von Pulsstromrichtern auf Bahnfahrzeugen mit Wec:hselspannungseinspeisung (Origin, propagation and impacts of harmonics in the AC traction power network). Bergisc:he UniversitatGesamthochsc:hule Wuppertal, 1987, dissertation thesis. 13.7 Muller, K.: Beitrag zu Entstehung, Ausbreitung und Wirkung von Oberschwingungen im Wec:hselstrom-Bahnnetz. Technische Universitat Dresden, Fakultat Verkehrswissensc:haften "Friedrich List", 1996, dissertation thesis. 13.8 Zimmert, G.: Oberschwingungsstrome im Gleichstromnetz durc:h den Einsatz of Gleichstromsteller-Triebfahrzeugen (Harmonic: currents in DC network due to the use of pulsecontrolled traction vehicles). HfV Dresden, 1975. dissertation thesis. 13.9 Zimmert, G.; Schmidt, P.: Resonanzverhalten des Gleichstromkreises gegeniiber Oberschwingungen of Thyristorfahrzeugen (Resonance behaviour of a DC circuit against harmonics in thyristor-controlled traction vehicles). In: Die Eisenbahntechnik 21(1973)10, pp. 453 to 455. 13.10 Koettnitz, H.; Pundt, H.: Berechnung elektrischer Energieversorgungsnetze, Mathematische Grundlagen und Netzparameter (Calculation of electrical energy supply networks, mathematical basics and network paramters). Verlag Grundstoffindustrie, Leipzig, 1968. 13.11 Koch, H.: Ein Beitrag zur Gewahrleistung der elektromagnetischen Vertraglichkeit of Anlagen der Sicherungs- und Fernmeldetechnik mit eisenbahntypischen elektrischen Systemen hoher Leistung (Contribution to secure the electromagnetic compatibility of installations for signalling and telecommunication technology with railway-typical electric systems of high power). HfV Dresden, 1986, dissertation thesis. 13.12 Lingen .J v.: Kurzschlussberechnung im Fahrleitungsnetz (Short-circuit calculation for contact line networds). TU Dresden, 1995, dissertation thesis. 13.13 Feydt;, M.: Vorschlage zur Verwendung der Kabelrniintel, metallener Rohrleitungen, der Gleise und der Erdseil-Maste-Kettenleiter als nat.iirliche Erder (Proposals to use cable sheeths, metallic pipelines, tracks and C!arthwire pole recurrent network as natural earth electrodes). Report of the Institute for Energy Supply Drc~sden, 1982. 13.14 Pollaczek, F.: {)her das Feld einer unendlich lang<~ll, wechselstromdurchflossenen Einfachleitung (On the field of an infinitely long single conductor used by AC current). In: Elektrische Nachrichten-Technik :1(1926), PIL :.trn to ;359 13. 15 VEM handbook: Encrgievcrsorgung clddrisclwr Balttwn (Pow<~r supply of electrical railways) Verlag ,n!c:l111ik, Bnlin, 1!)7;i.
13. 7 References
13.16 26. Bundesimmissionsschutzverordnung (BimSchV): Verordnung iiber elektromagnetische Felder (26th directive on the German Federal immission protection law: Directive on electromagnetic fields, edition 1996). Bunclesgesetzblatt 1996, Teil I vom 16. December 1996, p. 1966 13.17 International Radiation Protection Association (IRPA): Interim guidelines on limits of exposure to 15/60 Hz electric and magnetic fields. Health physic 58(1990), pp. 130 to 132 13.18 David E.: Elektrische und elektromagnetische Felder im Nahbereich von Freileitungen (Electric and electromagnetic fields in the vicinity of overhead power lines). In: Deutsches .Arzteblatt (1986)12. 13.19 David, E.: Wirkungen der Elektrizitat auf den menschlichen Organismus (Effects of electricity on the human organism). Speech at TU Dresden, November 1993. 13.20 Zimmert, G.; Hofmann, G.; Jecksties, R.; Kraft, R.; Schneider, E.: Ri.ickleiteroberleitungsanlagen auf der Strecke Magdeburg-Marienborn. In: Electric railways 92(1994)4, pp. 105 to 111. 13.21 Wahl, H.-P.: Messungen von elektrischen und elektromagnetischen Feldern bei Nahverkehrsbahnen (Measurements of electrical and electromagnetic fields in local traffic railways). In: Reports and information on HTW Dresdei1 4(1996)1, pp. 39 to 41. 13.22 Fischer: Diskussionsbeitrag auf dem 2. Symposium des Fachbereiches Elektrotechnik der HTW Dresden am 16./17. November 1995 (Contribution to the 2nd symposium of the electrotechnical department of HTW Dresden, November 1995). 13.23 Bette, U.: Messungen in Betriebshofen und an Verkehrsbauwerken (Measurements in depots and general traffic installtions). In: Reports and information on HTW Dresden 4(1996)1, pp. 89 to 101. 13.24 Runge, W.: Elektromagnetische Vertriiglichkeit bei Bahnen - Normen und ausgewiihlte Probleme (Electromagnetic compatibility at railways - standards and selected issues). In: Reports and information on HTW Dresden 4(1996)1, pp. 27 to 38 .
--==----
.tr-.mvd<
728
13 Electric traction cor~~~1ct lines as emitters of electromagnetic disturbance
:_=.::::.__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
14 Erection and operation 14.1
Basic definitions
The erection of an overhead contact line system includes all construction and assembly work, using components produced to reach a suitable quality, as well as the final acceptance procedures. A test operation is part of the acceptance procedure. It starts after the commissioning of the system, which simultaneously launches the operating of the overhead contact line. The term management in this context is the operation of the electrical equipment and work in the electro-technical system with the objective of achieving a high availability. Figure 14.1 illustrates the structure of the activities included in the mangement.
14.2
Erection
14.2.1
Principles
Individual railways administrations have defined their own principles for the erection of overhead contact line systems in their regulations and guidelines based on international and national standards (Appendix 1). At DB, these are the DB directive Gbr 997 and the Ebs Design Boole The planning described in Chapter 6 is a prerequisite for the erection and subsequent operation.
14.2.2
Production and testing standards for components
Components of a suitable quality are a condition for the assembly of operationally safe and long-lasting overhead contact line systems. Their manufacture requires special
Management
Work
Operate
Monitoring
Altering
Setting
Switching
Adjusting
Controlling
Figure 14.1: Strnd111e of activitic0 during operation.
Preventive maintenance
____ 14 Erection and operation
Table 14.1: Production and testing standards for components. Component
Production and test standards
Poles and foundations Contact wires Stranded conductors
DIN 1045, DIN 4228, EN 10 025 EN 50149, UIC 870, DIN 43140, DIN 43141-1 IEC 61 089, UIC 870, pr EN 50 345
Conductor rails
DIN 17122, DIN 50 142
Insulators
IEC 60383-1/-2, IEC 60672-1/-2/-3, prEN 50151, IEC 61109, IEC 36(SEC)96/101/106, IEC 61952, IEC 60112 / DIN VDE 0303-1, EN 50119, DIN VDE 216/-2, EN 60660, EN 60383
Fittings
DIN VDE 216
Section Insulators Disconnectors
EN 50 119, DIN VDE 0216 EN 50 119, EN 50 152-2, EN 50 123-4
Figure 14.2: Test laboratory at Siemens AG in Ludwigshafen.
materials, technologies, knmvledge and experience, due to the distinctive demands and operating conditions of electric: 1rtilway systems . The suitability of new products is to be verified by means of approval procedures_ A quaWy assurance system in accordance with the standa.rcls series EN ISO 29 000 is a prerequisite for this. In addition, electric railway operatnrs publish technical conditions of ddivery for individual components. Prnduchon and /;est sto:rulu,rds for selected components arc contained in Table 14.1. The selection of the mechanical. dy11c1mic, electric-,tl and chemical test standards and conditions to lw p<~rfor!ll<~d as a result of tl1('S<~ wglllations requires comprehensin'
l'L:2__Erection
731
Figure 14.3: Test of a voltage limiter (left) and an overhead line disconnector (right) at FG H Mannheim.
knowledge of the operational conditions and the loading cases for all overhead contact line components. Figure 14.2 shows a test laboratory for mechanical tests on overhead contact line system components. The testing of a voltage limiter (left) and an overhead line disconnector (right) can be seen in Figure 14.3.
14.2.3
Construction and asse1nbly work
14.2.3.1
Introduction
Construction and assembly ·work for an ovPrhead contact line system include 1turnerous steps (Table 14.2). The work starts with the foundations for the poles. The erechon of poles, mounting of cant-ilevers and head-span structures, the \Yheel-type tensioning devices and midpoint anchors in preparation for the subsequent ·installation of the !'.ont.acf; line foll0vvs. The installation of the railwa,· earthing completes the work.. Implernentation documents such as pole and foundation tables, material lists and cont:act. lzne layouts ·with referet1ccs to dr!sign books for the specific type of overhead contact line ( chapter 6) form tlw basis for the work. These documents are subdivided into project books for the individua.l stations and oprn track sections. The a,11011nt of' work is d<·<·l ri("
--------------~~---
·--·-·--------------·-
732- - - - - - - -
___,.
___________________________________ _
14 Erection and operation
Table 14.2: Tasks and working steps for the erection of overhead contact line systems. Working steps
Tasks Foundation
Survey of locations, search for cables, secure ballast, excavating, scafolding, drilling, ramming, fix anchor bolts, installing foundation earthing, vibrating and pouring concrete
Set poles
Attach brackets, clean excavation or hole, mount or insert pole and align, pour concrete or underfill poles
Preparation of cantilevers
Calibrate poles, calculate cantilever dimensions, saw tubes and drill, cut thread, mount fittings and insulators
Cantilever assembly Mount tension wheel assembly
Bolt cantilever to pole and secure against turning, remove transport protection from insulators Insert and secure wheel, install weight guides, complete weight stack and messenger wire and contact wire termination
Midpoint anchor installation
Install midpoint anchor, attach ropes for messenger wire midpoint anchor and tension to the specified force
Preparation of droppers and stitch wires Install contact line
Measure contact wire support clamp, calculate and manufacture droppers, cut stitch wires to length String the messenger wire and contact wire singly or together into the overlap, connect with the tension wheel at the start of the tensioning section, string under tension, clamp into the cantilever and terminate at the midpoint anchor and the tension wheel assembly at, the end with the specified tensile force, release the tension wheel assembly during this, install the stitch wires and droppers during the stringing work, install the contact wire midpoint anchor, tension the stitch wires Check the contact wire height and stagger and adjust if necessary by altering the cantilever and dropper
Adjustment work Install over head line disconnect.or
Install and adjust drive mechanism, linkage and disconnector parts, connect remote control cable and power feeder or switching lines
Install traction supply power line (TPSL) Plates and labels
Fasten insulators, string TPL, tension and clamp in
Attach pole, disconnector and TPL numbers, attention and warning plates at the prescribed positions
Rail way earthing
Connect metal parts in the contact line range and poles with the selected rails, lay and connect earthing connections, install voltage limiters in DC systems
Revisions
Correction of the documents to comply with the installation
traffic on an existing track with restricted track closures. The main characteristics of selected methods that have proven tlwmselves on DB lines are described below.
14.2.3.2
Foundation and pole setting work
Depending upon the soil conditions at the\ installation site, the static loading, the pole t_vpe and economical reasons, Ott<' of' sevc\rnl foundation types can be selected for the poles. They ('an lie ('lassifi<'d with n\s1wd, to
-
14.2 --Erection -~----------·-------~
733
type of erection iu drilled, piling and excavated foundations, static actiou in fiat and deep foundations and foundation shape in block, stepped block, tube pile and H-beam pile foundations. Especially driven p'iles have shown themselves to be economically attractive in Germany. H-beam piles with a tube welded on top are inserted into the ground using a mobile pile driving machine. A concrete pole is then put on the tube, aligned and the space between tube and pole is fitted up with mortar This method is characterised by low labour content, quick progress and the avoidance of extensiYe concreting work under unfavourable conditions experienced with railway operations. Drilled .fo'Undations are used in rock. A future exchange of concrete poles is possible with a foundation type with which the poles are inserted in a pile tube with stone chippings and a concrete cover layer (Figure 7.37). Mounted steel poles stand on prefabricated or in-side cast concrete foundations with embedded anchor bolts (Figure 7.34). Railway wagons transport the necessary pile driving and drilling machines and the concrete mixing vehicles to the foundation location. If the foundation work is performed prior to the laying of track, as is often the case with new lines, then access should be possible over temporary roads or via the unfinished track bed. Special concrete mixer trains can be employed for extensive concreting work along the track. With new engineering structures, the attachments for any kind of structures can be integrated into the structure and prepared already during the erection of the tunnels, bridges, embankments and platforms. The foundation work is a part of extensive construction works and therefore requires appropriate co-ordination with the erection of track, signalling, telecommunications and station installations. The relatively expensive construction of foundations using cross-co'Untry S'Uited vehicles operating outside the track and the setting of poles during traffic operations using helicopters trans an alternative to track closures on heavily loaded railway tracks. Depending upon the method of pole setting, an extensive pre-assembly of fixing brackets, tension wheel assemblies, etc. on the poles can be performed before leaving the storage sites. 14.2.3.3
Erection and adjustment of the overhead line supports and contact lines
Completion of the pole foundation, supports setting and track work and the procurement of the entire material requirement are the prerequisite for further activities. The cantilever dimensions can be calculated on the basis of the suneyed pole positions. If cro8s-span 8tructures are planned, their erection requires the closnn~ to rail traffic of all tracks to be spanrwcl. Portals and cantilevers across several tracks are attached to the poles with the aid of cranes. Pulley systems and, at special locations, helicopters are employed to install prefabricated head-spans. If possible, the cantilever supports and the ccatact line within a v~nsioning section are installed during one technological sequence, depending upon the aiuount of work and the track availability. The t<~nsioning wheel assembly and the midpoint anchors must lw installed bdordrnnd.
14 Erection and operation
,34 Direction of travel
Figure 14.4: Arrangement of installation trains applied for integrated overhead line installation.
Figure 14.4 shows the integrated overhead line installation on cantilever supports that can be employed on the open track. The cantilevers that have been pre-assembled in the workshop are transported on a conveyor belt to the working platform on the first contact line installation train and attached to the poles by means of a laterally swivelling platform. After threading and fastening the messenger wire and the contact wire to the fixed tensioning wheel assembly at the termination pole, the second installation train with the drum wagon follows. The bull-wheel type wire-braking device on the drum wagon strings the messenger wire with the specified messenger wire tensile force already during stringing, and the contact wire with approximately 3 kN. The observance of these values, especially during acceleration and braking of the installation train is decisive for the avoidance of bends and kinks in the contact wire. Laterally swivelling and height adjustable rollers guide the messenger wire and contact wire into position above the raised platform on the third installation train to enable their attachment to the cantilever. The contact wire and stitch wire are installed using wires as temporary droppers, after attaching the messenger wire to the messenger wire suspension clamp. The third installation train continues with the installation of the messenger wire midpoint anchor and the termination of the contact line at the termination pole. The described integrated installation method can be amended further. A second contact wire on DC overhead lines can be strung and attached simultaneously. If full availability of the track for electric traction vehicles is not needed immediately after stringing the contact line, the height of the messenger wire suspension clamps at the cantilevers can be measured to provide the basis for the calculations needed for the preparation of the droppe'rs. This intermediate step has shown itself to be advantageous, since it allows a rationalised prefabrication of droppers in the workshop, which achieves a high degree of accuracy of the overhead line geometry. If the overhead contact line system must be used for electric traction vehicles immediately after contact line stringing, then the third installation train already uses the droppers for the attachment of the contact wire still strung with reduced tensile force. The data on the rail height mark at the pole provides the calculation basis for dropper fabrication before the installation of the contact line. In this case, a fourth installation train commences the adjustment work (see Table 14.2 and Figure 14.4) in this section, aft,er the third installation train has reached the midpoint anchor, and the tensile force on the contact wire in the first tensioning section has been set to the required value with the tension whed assembly released. When the third installation train has reached tlw ten11inatio11 pole, tlH~ll it n~-teusions tlw mcssr\ng<\r wire and contact wire. The in-
14.2 Erection
stallation traiu finally travels back in the direction of the midpoint anchor, adjusting the contact line in the second tensioning section half The ad_justmenl work includes such tasks as clamping the droppers, tensioning the stitch wire and checking the contact line structure with respect to its planned geometry and the co11tac:L wire uplift when loaded. Deviations from setpoints that are outside the permissible tolerances must be corrected. Appropriately modified installation techniques are employed on already electrified tracks with dense traffic, on which the existing contact line must be dismantled first. There can be several reasons for the dismantling of the old contact line. Existing pole spacing is often unsuitable for the intended speed increase or components, such as poles or contact lines have reached in total the encl of their useful life due to wear or ageing. In such cases, an addition installation train precedes the first installation train shown in Figure 14.4, which performs the de-installation of the existing contact line. An increasing mechanisation and reduction of the working times influence the development of the installation methods. The installation vehicles and equipment described in clause 14.7 permit the de-installation, complete installation and partial adjustment of a tensioning section in less than six hours. Integrated contact line stringing is normally not possible in stations clue to the contact wire intersections or head-spans and the messenger and contact wires have to be installed consecutively. Integrated installation units can also be employed in place of individual installation trains. The duration of track closures and the type and scope of the work significantly influence the employment of heavy-duty construction equipment. The costs of ownership and for the necessary operating staff are high. The duration of use and, therefore, the efficiency is mostly low clue to short closure periods for working on the line. Mobile ladders are therefore still employed for a part of the work, such as de-installation or adjustment of the contact line structure. These can be lifted from the route track manually to make the track available at short notice. Installation-friendly designs, such as aluminium cantilevers and brackets or GRP tubes combined with copper-aluminium alloy fittings, compression connections or plug-in clamps simplify and accelerate the work. Two to four fitters are employed on each installation train. In addition, traction vehicle drivers, installation trai11 drivers, equipment operators, lookouts and supervisors are necessary. The track closure period detennines the scope of the equiprnent and also the efficiency of the staff deployment. Closures of 3 to 8 hours per track are usual. The wiring of crossovers requires the short-term closure of several tracks to regular traffic. \\'ork on upgraded lines can become very c:ornplicated clue to operational constraints, track closure delays caused by train delays, switching, earthing and release procedures that are necessary before work can commence, and travel into the blocked track as \Yell as the necessary protection measures for the construction site. The owrhead contact line system can a.lso be installed during the night in exceptional cases with especially dense track loading. The prerequisite for this is the provision of~ at is factory lighting on the installation trains and additional protection rneasures against the clangers caused bv train operations during the night. A sufficiently accurate! ad_just!llcnt of the O\erlwad contact line is ver,v diffirnlt under such couditions. Longer tn1< k closure p<'riods are lw11dicial for work
14 Erection and operation
736
Table 14.3: Permissible tolerances for the installation of DB's overhead contact line Re 330. Paraineter
Tolerance
Distance between rail and foundation top surfaces or driven tube (dimension E)
± ± ± ±
50mm
± ± ± ± ±
500 mm
Distance between track centre line and pole front face (dimension TP) Pole inclination Pole turning Span length System height Contact wire stagger at steady arm Contact wire height at support Contact wire height from dropper to dropper
50 mm 0,3° 50 150 mm 30 mm 10mm 10 mm
efficiency. Working in a completely block track, 12 tensioning sections on one track can be completed between Friday evening and Monday morning. Erection work restrictions can be caused by weather e. g. during heavy frosts and at wind speeds above 10 m/s, depending upon the deployment regulations for the working platforms and cranes. Work on the overhead line is to be interrupted during approaching thunderstorms. The development of low-maintenance high-speed overhead contact lines has placed increasing demands upon the quality of the installation of the overhead contact line. The reliability and service life of the components are influenced decisively by careful transport of materials to the construction site, correct installation of the fittings and insulators, thorough greasing of current connection clamps and observance of the specified torque for bolt connections, etc. The employment of special materials such as copper-silver or copper-magnesium alloys for the contact wires, and the resulting higher tensile forces, require special tools and appropriate specialist knowledge on behalf of the fitters. Well- trained staff is therefore a prerequisite for the installation of a high-quality overhead contact line. The wearing characteristics of the contact wire and pantograph collector strips are directly influenced by the geometrical accuracy of the contact line. Table 14.3 contains the permissible tolerances for the installation of DB's overhead contact line Re 330. 14.2.3.4
Installation of section insulators, cross-over contact lines, traction power supply lines and railway earthings
The contact wire is separated under tensile force for the installation of the section insulator and attached to the ends of the section insulator. An insulator and the suspension are also to be installed in the messenger wire above. Since section insulators cause elasticity differences in the overhead contact line as a result of their mass, the height adjustment of the entry and exit sections and of the gliding skid has a significant influence on the pantograph dynamics and the avoidance of early wear.
.I I
14 .3 _0 pent LP _____ _
Care must be taken cl uring the installation of the contact lines over crossovers to ensure that both contact wires in the pantograph entry area are located on one half of the collector head, since collector head traps can otherwise arise. Earthing lines in AC systems are attached to the poles and the metallic equipment located in the area of the overhead line and to the provided connection points on the rails, possibly ·with the inclusion of return current or earthing conductors. Since this work hardly requires track closures, it can be performed before and after track closures, thus spreading the staff workload. DB attaches the railway earthing lines to the rails using bolted connections. Correct earthing installation providing sufficient covering for the earthing, e.g. with ballast, as protection against damage by track laying machines. Traction power supply lines (TPSL) can be installed using traditional conductor pulling processes [14.1] or with the help of helicopters. The co-pilot operates the brake device on the conductor drum and ensures a constant tensile stress in the conductor. V-shapecl catching aids on the post insulators simplify the insertion of the conductor.
14.2.4
Acceptance and commissioning
Acceptance of the overhead contact line system consists of a technical and a contractual part. The technical acceptance is the test of the functional safety and compliance with the safety requirements by an electrotechnical expert. It includes intermediate acceptances, e.g. visual inspections of excavations, cable trenches and foundations, a provisional acceptance in the form of inspection runs with recordings of the static and the lifted geometry of the contact wire, commissioning by energising the overhead contact and the traction power supply lines, trial operation and final acceptance. Announcements and cautions are to be issued before connecting voltage to the overhead contact line. Trial operation of the overhead contactline has duration of, for example at DB, three months. During this phase, an acceptance run with the rneasuring car is made at the specified line speed, and the final acceptance performed b~- means of the status tests Zl and Z2 (clause 14.5). A declaration of the contractual acceptance. the hand-over of the revised drawings and other installation documents follow and the guarantee period with different periods specified for the individual components commences. DB performs a complete inspection before expiry of the guarantee period.
14.3
Operate
14.3.1
Training and instruction of staff
Tlte operation of o, crll(';1d rn11t act line systems assumes the availability of trained and exp<'1iet1c('d staff C11idc,littc's and sc'rvicc regulations defin<' work SC\(!lH'nccs and
-------------------------------~=--=·=·- - ~ - - - - - -
738
14 Erection and operation
conducts. They enable new staff to gain knowledge of operation actions and working in overhead contact line systems. The objective of staff training is to convey knowledge of the correct execution of work and the recognition of possible dangers during irregularities and incorrect conducts. In accordance with the knowledge and degree of difficulty of work in overhead contact line systems, differentiation must be made between Nominated person in control of a work activity: That person who has been nominated to be the person with direct management responsibility for the work activity. Parts of this responsibility may be delegated to others as required (EN 50110-1), Nominated person in control of an electrical installation: That person who has been nominated to be the person with direct management responsibility for the electrical installation. Parts of this responsibility may be delegated to others as required (EN 50110-1), skilled persons: A person with relevant education and experience to enable him or her to avoid dangers which electricity may create (EN 50 110-1), instructed persons: A person adequately advised by skilled person to enable him or her to avoid dangers which electricity may create (EN 50110-1), railway system instructed persons, who do not perform work on overhead contact line systems, but have knowledge of possible dangers when working on railway equipment on electrified lines and Ordinary person: A person who is neither a skilled person nor an instructed person (EN 50110-1). Corresponding to the character of the activities in overhead contact line systems, electrotechnical specialist knowledge and also the operational experience equally form the pre-conditions for the prudent execution of operator actions. An electrically skilled person has completed an electrotechnical education in accordance with EN 50 110 Part 1 as an electrical engineer, electrical foremen or electrical fitter. Special requirement profiles for electrically skilled persons define minimum knowledge levels for conduct in railway operations. The electrically skilled person assigns the type and scope of work to the electrotechnically instructed person and supervises this [14.2]. The railway system instructed person performs work on electrified lines, but not in overhead contact line systems, and can recognise the dangers of electrical train operation after the instruction received from the electrically skilled person and conduct himself accordingly. Regular and also certifiable instruction refreshes and deepens the knowledge. The topics are arranged to cover a period of two years and include all important electrotechnical conduct standards and service guidelines and the evaluation of disturbances and accidents.
14.3.2
Electrotechnical conduct standards and service guidelines
Technical definitions assist users and operators in the recognition of dangers that can occur as a resnlt of incorrect conduct in respect of electrotechnical equipment and
.i
739
systems. The international standards serve as the basis for generally accepted rules for good engineering practice. Erection and (\quipment standards relate to the erection, commissioning and properties of equipment and systems. Operating standards such as EN 50 110 standardize the conduct aud procedures of the users and operators in the form of general definitions. Internal company regulations, such as the current DB Guidelines - Gbr 462: Operation of the ove·rhead contact line network, amend the definitions contained in general standards for railway-specific situations [14.3]. The arrangement of the modularly compiled DB Guidelines Gbr 462 in 'basic principles', 'operational management', and 'working on and in the vicinity of the overhead contact line' corresponds to the definition of terms in EN 50 110 with the subdivision of management into operate and work. All definitions necessary for operation are contained in this guideline. The Austrian Federal Railways summarise in EL 52: Electrical operations regulations, the internal operational definitions, which are divided into general regulations, safety measures for working purposes and special regulations that refer to operation.
14.3.3
Switching
The active parts of the overhead contact line system are normally energised. Operational management, maintenance work and disturbance events necessitate switching operations. The switching diagram shows the designation and normal position of the disconnectors, their assignment to switching groups, conduct during hazards and the location of earthing and short-circuiting devices and voltage testers. Only persons trained to do so may perform switching operations; at DB these are switching command controller, switching applicant and disconnector operator. The switching sennce rnanagers in the area power supply control centres with the highest qualification in switching services at DB are the switching command controllers. They must gain and prove the knowledge during a training course with a subsequent examination. They can perform switching operations independently under their own responsibility, or issue switching instructions for the execution of switching operations by other persons. The switching command controllers are simultaneously the operators for remotely contrnlled disconnectors. Switch operators, who have received training at DB as a switching ;:1,pplicant, s,vitch locally controlled or manually operated switches. There arc included traffic superiutendents on electrified lines, - staff members in a technical department and - staff members carrying out erection and supervision work. The training irn:luclcs lrnowlcdge related to the design of the overhead contact line system, their layout plaus with switching iustrnctions, lrnzards iu dectriccll train operatious, control and operation of overhead coutac:t line disconnectors, holding s\\'it.cliiug dialogll<', S\\'it.cliing 1111
.,
7--10
14 Erection and operation
- recording switching dialogues and - behaviour in dangerous situations. Proof of the acquired knowledge is performed during an examination. The switching operation itself is performed on the basis of a switching dialogue, whose process is recorded formally. The switching request at DB contains name of the system parts to be switched, e.g. X-town Station, switching group I, type of switching operation, e.g. open, permit from the traffic superintendent for operational closure of the track and identification of the applicant with code number. After approval of the switching request, the central control centre can issue a switching instruction to open disconnect.ors or perform the switching operation itself. After opening the disconnector and protecting it against unintentiona,l re-closure, the switching manager at the central control centre confirms the execution of the switching operation to the switching applicant. A disconnector is tagged with a 'permit' label after the issue of a switching permit to a switching operator and safeguarded against further operation. The disconnect.or becomes available for further operations by the switching manager only after the cancellation of the permit. The switching operation is performed after the closure of operations by the traffic superintendent on all tracks included in the circuit group to be switched off. Disconnectors within one's own authority are. also to be safeguarded against unintentional re-closure. The maintenance work can commence after checking that the line is de-energised, earthing devices are applied in front of and behind the working location and the supervisor has verbally instructed the maintenance team of the working limits and special hazard situations. The switching applicant is to be continuously available during the disconnection period of the switching group. After completion of the work, the supervisor reports the safe operational state of the overhead contact line system to the switching applicant. The s,vitching applicant reports to the switching manager that the contact line is ready for re-closure and reinstates the normal disconnector position after receipt of an instruction, or independently if it is under one's own authority, and cancels the operational closure. If several switching permits have been issued for a switching group, the re-closure may be performed only after all applicants have reported readiness for a re-closure to the switching manager. The switching dialogue with approval of the traffic superintendent for the operational closure of the tracks and all subsequent information relating to d1e switching operation are to be documented in the telephone book for switching operations or to be recorded on the voice recorder in the central control centre. The equipment needed to check whether the line is energised and to install the earthing are located at the stations and are to be inspected in 5 or 2 year intervals. Instruction with the repeat of service reg11l1:1tions related to switching serve to avoid incorrect actions and to train safe aetiYitv sequenc:es. Regular accident preventfon training assists the consolidation and review of the knowledge gained.
.I I
1_4:L!_ Wear and ageing __ _
14.3.4
741
Irregularities and their recognition
The opera.tor provides a current reporting plan for conduct during -irregularities and d1:stur-bances in the overhead contact line network, from which the necessary actions and the information flow can be recognised. As a general rule at DB, reports c:onverge via telephone links at the switching manager in the central control centre, who undertakes the necessary measures. After circuit breaker trips, an automatic check of the freedom from short-circuits is performed, and if the result is positive, the feeder section is re-connected. If a sustained short-circuit is present, the fault position should be localised as accurately as possible to assist the repair team to travel to the fault quickly. The fault position is immediately blocked with the traffic superintendent, isolated and transferred to the switching applicant in the repair team with a notice of isolation. Rapid earthing of the disconnected overhead lines is necessary to avoid travel into neutral sections with arcing and damage. Close co-operation between the central control centre and the traffic superintendent assists to establish the fault causes quickly and to prepare the repair team for the fault by radio while they are still travelling. After clarification of the necessary time needed to perform the work, the leader of the repair team gives his time estimate for the railway operations management and attends to the rapid removal of the damage. Provisional solutions with 'dropped pantograph sections' can definitely help to restart train operations and to reduce the train tailback. It is possible to regain the condition of the overhead contact lines during track closures arranged on a more long-term basis. Irregularities and deployments for overhead contact line system fault removal are recorded in prepared forms. These are to be sent to a pre-defined distribution list within certain time limits and assist the statistical analysis (clause 14.5).
14.4
Wear and ageing
14.4.1
Classification of components
The components 1>n an overhead contact hne system can be divided \Yit h respect to their loading in components with mainly mechanical loads, such as poles and support devices and with both electrical and mechanical loads, such as overhead contact line equipment, railway energy supply lines, section insulators, disconnectors. current connectors and cuneut carrying clamps. System co1npouents of c-ontact line systems arc subject to agC'ing aucl c'kctrical and mechanical wear, which are dependent upon the period of use and the magnitude and the duration of the load. Knmdedge of wear and ageing processes arc of essential import;-wcc for maintc11,t11c<)
14 Erection ,~nd operation
742
14.4.2
Concrete poles and foundations
Corrosion is the destruction of material resulting from chemical and electrochemical processes. During electro-corrosion, metals oxidise as the result of a chemical reaction, which is usually accompanied by current flow. Stray wrrent corrnsion is included in this. Electro-corrosion however also occurs without an external current source, e.g. by means of metals with different positions within the electrochemical series or as a result of nonhomogeneity of different surface sections of a metal, which provoke potential differences. Air humidity or soil as an electrolyte is sufficient to start the reaction. In accordance with Faraday's first law of electrolysis as in equation (12.22), the anode components are destroyed. The metal erosion is proportional to the quantity of current flowing [14.4}. Concrete consists of solid, liquid and gaseous components. The protective effect for the reinforcement is not brought about by the hermetic inclusion, but rather by the alkalinity of the interstitial water with PH = 12,5 to 13,5. By forming a protective layer this helps curb corrosion. This process becomes reversed after a drop in the concentration of calcium oxide hydrate. The cause of this drop can be cracks and carbonisation or the presence of activators in the concrete. Possible activators are calcium chloride to accelerate the setting time and sodium chloride as frost protection during pole manufacture in winter or as de-icing material on roads. There is no further continuous protection for the reinforcement when the cracks exceed 1 mm or concrete cover layers are less than 20 mm. The following influences act on concrete mechanical loads and compression, water that washes out calcium hydroxide, whereby calcium carbonate is formed, recognisable by white stains, carbon dioxide in water and in the atmosphere, which leads to chemical decomposition and stresses in the capillaries in the concrete and inside the poles caused by repeated freezing, with a volume increase of 9 %, and thawing of water and also by solar radiation and cooling by air currents. Damage to poles that do not have electrical causes, such as crack formation, the separation of the concrete from the reinforcement, the effects of aggressive materials, etc., are less dangerous than, for example, stray current corrosion, but occur more frequently. The effective prevention of the described d::i.mage is possible by observance of the necessary concrete and production quality, including follow-up treatment. The concrete strength is therefore to be selected not only from the viewpoint of stability but also of durability. Experience [14.4] shows that satisfactory protectiou against weathering, acids and carbonisa.tion can be achieved with a water (w) t,o cPment ( z) ratio w / z < 0,45 and a cement component Z > 300 kg/m 3 . The concrete poles employed by DB during thr. last 15 years have w /z ~ 0,35 and Z ~ 400 kg/111 3 , and therefore possess good qualifications for railway applications. Stray current corrosion occurs on DC railways if return currents flow through undergrmrnd seC'tious of fo1111da(,iom.; and pol<'s. To avoid this phenonwnon, the electrical
743
interconnection of poles, foundations and rail:,, either individually or in the form of collective earths, essential for protective tripping during insulation faults are normally executed only by means of voltage limiters or spark gaps. If they are defective or if a direct contact is made, then a continuous current flow can occur dependent upon the potential differences and resistances present in the ground. Even a current density of 0,06 A/m 2 can cause the start of electrical corrosion of underground equipment. The earth electrode re:,i:,tance of a concrete pole can be between 3 and 3000 n, but does not normally exceed 30 n. Damage to concrete foundations have been observed on DC railway:, mainly at a depth of 0,4 to 1,0 m and over a length of 0,5 to 1,0 rn. The destruction of the protective effect of the concrete cannot be reversed. This means that the reinforcement continues to corrode even after the removal of the cause of the stray current corrosion. The prevention of current flmv through concrete poles and foundations therefore gains special significance. Experience shows that the service l~fe of concrete poles under normal operational conditions can be 60 years and more.
14.4.3
Steel poles, cantilevers and other support structures
Damage to metal structures can be classified as follows: corrosion, deformation clue to external influences, such as train derailments, brittleness and low temperatures and deformation at high temperatures, mechanical overload clue to errors during planning or installation and electrical erosion. The destruction prncess under static tensile loading of metals begins with the presence of defects in the crystal lattice. These include vacancies, inclusions, dislocations and surface defects. Fatigue or ageing lead to structure changes and to the accumulation of dislocations, which favour the creation of micro-cracks. Besides destruction caused by overload, fatigue from cyclic loads that do not exceed the material strength under static loading is also possible. The main cause of corrosion beside aggressive materials has been proved to be the limited durability and the tardy renewal of the corrosion protection of steel components. Steel poles rust especially at the fixing point in the foundation concrete or the foundation cap. These positions can be protected durably only by means of elastic coating :,ystems. Corrosion is assisted under continental climate conditions by sulphurous gases, mainly at temperatures between 0°C and 15°C and under coastal conditions by salts with their cltlorine ion:,. A fluid electrolyte layer is a prerequisite. The rate of corrosion is up to six times higher in industrial region:, that in rural areas clue to the increased air pollution Hot-d'/,p galva:nzsatzon has been employed as corrosion protection for steel components for 140 vears. The zinc forms protective layers after weathering, which ensure the prntectiou of' the lower layers. They are however eroded by wind and weather. The originally apprnx:imatel_v 85 /Hll thick zinc- layer on a cautil<~vcr or steel pole is reduced cad1 _,·car 011 avern.gc h_v 2 11.m in rural areas, ;3 11,m in urban areas and up to 20 JJ,m in i11dt1strial 01 (·oastal an'as [1-l.5]. S11pplernentarv coatings arc 11('.Ccssary when the
I' !:,
14 Erection and operation
residual thickness has reached 40 pm. Corrosion is also dependent upon the design and arrangement of the components, since these offer varying conditions for the accumulation of dust and moisture. Since the mid-80s, aluminium cantilevers have become popular in Germany as an alternative to hot-dip galvanised steel cantilevers with hot-dip galvanised malleable cast iron fittings and with regular renewed coatings. Aluminium has proved itself to have a relatively high resistance to corrosion, since it forms a dense surface oxide layer. The protective effect is not lost after mechanical damage, since the protective layer renews itself. Aluminium possesses a favourable behaviour in the case of short-circuits due to its conductivity, which is a factor 10 higher than steel, and its doubly high specific heat. The service life of hot-dip galvanised steel components maintained by timely renewal of the coatings is estimated to be longer than 70 years. Experience with aluminium components already shows a service life of over 80 years without corrosion protection measures. The attachment of steady arms to the drop bracket with a loose fit can lead to mechanical wear. DB therefore specifies a steady arm minimum tensile force of 80 N for overhead contact lines. Electrical erosion occurs on DC railways when partial currents flow through movable, non-insulated connections (Figure 14.7 left). Voltage differences of 15 to 20 V already lead to erosion of the metallic parts due to small electric arcs. These phenomena can be avoided by the provision of electrically conducting bypasses or electrical insulation at these points.
14.4.4
Traction power supply lines, messenger wires, droppers and connectors
Traction power supply lines, messenger wires, droppers and connectors are subjected to a high electrical loading and mechanical stresses from tensile loads, climatic factors and vibrations that can lead to fatigue phenomena, wear, corrosion and glow-out. Vibrations, especially near mass rnncentrations such as clamps and insulators, are the cause for the fatigue. They can lead to reduced strength and cracks. The high degree of corrosion resistance of aluminium components can be explained by the formation of a protective oxide layer. When polluted by alkaline and salt-containing substances, aluminium however corrodes faster than copper. Bimetallic copper-clad steel conductors, which are emplo;ved in several countries for contact wires and messenger wires, are subject to severe corrosion in sulphurous air. Glow phenomena arise in the mentioned elements due to overloading by electric current in the event of incidents and locally under conducting clamps. The cause of clamp heating lies in the increase of the transition resistance, e. g. due to oxide layers on the contact surfaces, reduction of the bolt tightening torque or distortion after severe temperature variations. If only few external conductor strands are in contact with the contact surfaces of the clamp, these become overloaded and glow-out. The current flow shifts to other, internal strands and must now ov<\t-corne a higher transition resistance, which !C'acls to a rapid increase in the heating. The rnte of aqeing of connectors is
745
14A Wear and ageing __ _
a) tz;;zz;zzzt2;zz,2222222222222zW///1//1///d/2ip/21//Vfl2a727222c77722Zlll/l,tl222ZZZ2t;,t~
b)
~----~~"'-
-0
range of wear
~ ~-:· 1"C~,:'>~~~?.,~~~!':~~~":!ir'""~j,;-~~··~-'-'~·
:,;.,-A-"-~
~~~~~l~Jg~f ~~~~1:1J~!{~k@~t1~t~:iEt*;~~ij~&~t~·it?f?~;t*r=1~~£i£~1~~t ~ !~:,t}~;Q-.'\~~~~~·~1)?;2:~~;e.;:..~,. i: '''';}'"7:1::1:-;~0-,;1?,;:~~'::-.;;..-::";.!~~..~ l ..~-r;-.; ~t'~---~-~;...:.:~,.:_~.....
.
~~·7·
-
.
Figure 14.5: Reduction of contact wire cross section with ripples and kinks (a) and rough surface of a contact wire in a DC system after negotiation with worn-out contact strips (b).
directly dependent upon the current loading and is correspondingly higher on DC railways. A satisfactorily applied contact grease layer or crimped connections counteract these phenomena. The failure of connectors can lead to the glow-out of droppers that are not of sufficient current-carrying capacity. Potential differences of 15 to 20 V already form electric arcs and result in electrical erosion at the connection points. Droppers are also subject to mechanical loads from friction and buckling during the passage of pantographs. The degree of wear increases with increasing stiffness of the dropper, e. g. with current conducting droppers, thicker wire cross sections and reduction of dropper lengths. The service life of the listed components is largely load-dependent and varies from 10 to 70 years. Steel messenger wires employed in the past failed after six years. Copper-clad steel messenger wires used in Russia for 40 years have not experienced failures due to corrosion. The copper-clad steel conductor with a copper portion of 30 % of the cross section used by former DR at the end of the 80s proved itself to be insufficiently resistant to wear. The copper-clad steel conductors were therefore removed after being installed for three years.
14.4.5
Contact wires
The burdens typical for bare electrical conductors strung in the open also act upon contact wires together with the added demands caused by the passage of pantograph and the current collection. The latter lead to mechanical wear and to ageing due to heating and burn-up. The processes that occur are explained in clauses 9.5.3.3 and 11.2. Increased local contact wire wear has special significance. The causes of increased local stresses on the contact wire often lie at mass points in the contact line, which lead to more intensive wear due to greater contact forces, and to arcing as a result of insufficient or non-existent contact pressure between the contact wire and the pantograph. Similar phenomena also occur as a result of superimposed vibration in the contact line system. The passage of pantographs with rippling and kinks that can be caused by incorrect installation or during traffic operations, e.g. by loose tarpaulins on freight wagons, also cause increased cross section reductions (Figure 14.5 a). The point with the greatest local wear ultimately determines the service life of the contact wire. If 20 % of the cross section has been worn away, contact wire splice com1cctors or new conta.c-t. win~ S<'c'Lions must be employed at the affected positions.
_______ 14 Erection and operatior~
26~-----.-----------:--=------:-----,-, mm2 _ B._ate_gl ~ar~p~ li~t i~Ru~ia _ 24-1--------1-----:-------j-------i-1
22+-------lr-------i--------1-1
Fe! v N km/h
20
250 I 150
0
~ 12
1501150 s i'° 10 ~-~-~--1-----..-:....-::--------::~----=-
_=
8 -j---~~~~I=:_=_:::_=_:=_:::: _==-~~?'""--=---------t-:J 150 / 150 M
2 0
100
200
Current - - -
A
Figure 14.6: Comparison of contact wire wear values given in mm 2 per 1 Million pantograph passes for contact wires made of electrolyte copper, of CuAg0.1 (index S) and of CuMg0,5 (index M) for different contact forces Fe and running speeds v, dependent upon current. Measured value at test stand - - Measured value at DB during operation - · - Measured values at Russian State Railway
The maximum number of contact wire splice connectors per tensioning section for DB overhead contact line type Re 100 is ten, for Re 200 five and for Re 250 four units. If these numbers would be exceeded, then the contact wire must be replaced along its entire length, as required for example in Gbr 997.01 to 997.03 for DB AG [14.6]. The acceptable wear differs between individual railway operators. Different stresses can be observed on the individual contact wires of twin contact wires on DC railways, whereby the more severe local wear alternates between the two contact wires. The reason for this is uneven pantograph contact force distribution on the two contact wires and the associated different transition resistances between the contact wires and the collector strips, which results in current collection from only one contact wire or the other in certain line sections. Severe arcing due to unfavourable combinations of overhead contact line and pantographs or late renewal of collector strips lead to a roughened and partially softened contact wire surface (Figure 14.5 b). This can be re-smoothened only with considerable cross section losses at the contact wire and c.ollector strips. Experience shows that on AC railways with graphite contact strips, '10 000 to 80 000 km travelling distance and approximately two million pantograph passes respectively are the wear limits for the pantograph contact strips and contact wires. The corresponding values for heavily loaded DC railways with more than 2000 A per pantograph are only 20 000 to 30 000 km and less thau 100 000 pantograph passes. A statistically guaranteed, precis<~ statcu1ent for the e.1:pected abso/lf,te servu:e life is hmvcver not possible due to varying opc!rn.tioual conditions. Absolute wear values have been calculated from experime11Ls described in the publica.tions [1-L 7] to [14.8] and compared in Figure 14.G with the W<'.,H rat<'.S ad1i· and Hussia while operating 25 kV single pitas
14.4 .'Y~c1.r and ageing .
747
the given operational conditions: contact wires made of electrolyte copper wear fa,ster than silver alloys and these wear faster then magnesium alloys, the wear rates show minima dependent upon current, which tend in the direction of higher currents with increasing speed of travel ( wrrent lubricating effect, see also clause 9.5.3.3), the wear rate increases with increasing contact force, the total wear reduces under experimental conditions with increasing speed of travel. The following statements are possible for the expected contact line service life with a permitted wear of 20 %. The average value for the service life of a contact wire with a nominal cross section of 100 mm 2 with a rate of wear as experienced at the Russian State H.ailway is approximately one million pantograph passes. With average train headway of 10 minutes, the calculated service life is 19 years. A wear rate of 8 mm 2 /10 6 pantograph passes can be read off the curve in Figure 14.6 for a silver alloy contact wire that is used on a high-speed line. A calculated service life of three million pantograph passes results from this. For assumed train headway of 6 minutes, a service life of approximately 34 years results for the contact wire. Deviations from the designed height and stagger of the contact wire relative to the track are possible as a result of changes in the overhead contact line system or the track geometry during operation. Low-bearing soil, which had not been adequately considered during planning and erection of foundations may lead to pole inclination. External influences and the already described wear phenomena can lead to deviations in the tensile force distribution in the contact line system and to the displacement of clamps. Experience gained in Germany during the erection of high-dv,ty overhead contact line systems shows that such effects can be reduced to a minimum. Furthermore, changes to the height and alignment of the rails occur during train operations and as a result of permanent way maintenance. Regular inspections (clause 14.5) are necessary to ensure that these processes do not lead to pantograph clewirernent or increased wear.
14.4.6
Insulators
The behaviom· of ir1,.sulator.s with tirne is determined by their 1ncchanical and electrical stresses. It is also dependent upon the type of design and the materials employed. If an insulator in a cantilever failed under tensile or compression and bending loads, this could lead to damage of the pantographs and then, resnlting from this, would tear down the overhead contact line along the full braking distance of the train. Similar effects could ensue from failures of the dead-end insula.tors, which are stress<~cl by tensile forces and frequcn(.l_v by vibrations. Arcs occur at the insulators as a resnlt of flashovrTs, e . g. caused by birds, lightning overvoltag<)s or SC'\"t'n' poll11tio11. They damag() gla'l:es and pol\'llJ()!' s11rfaces by forming
14 Erection and operation
748
___ -1,.. .. -·
-
:-· _.,-
__..-/
u . I I
i
j
~ /
-----,---
Figure 14. 7: Electrical erosion by DC (left) and cracks in quartz-porcelain insulators (right).
burn tracks and partially destroy the insulator sheds. They can also cause insulator fractures. Partially damaged insulators are to be localised with the aid of short-circuit location techniques and replaced then, since they would lose stability due to the defects and the penetration of moisture. Erosion effects and early ageing can occur on moist and polluted plastic insulators due to electrostatic partial discharges. The degree of pollution on contact line systems is more severe than with overhead power lines due to mixed traffic with diesel traction, the swirling up of dust and the transport of raw materials that react aggressively in the atmosphere. The pollution particles contain ion-forming materials that combine with the moisture in the atmosphere to form electrolytes. A moisture layer composed of small droplets of dew or drizzle is especially dangerous. The resulting creepage currents heat the surface and lead to an increased conductivity of the electrolyte, which possesses a positive temperature coefficient. The surface dries out simultaneously. The mentioned partial discharges and flashovers are created in dependence upon these processes. While long-rod insulators are puncture-proof, puncture can occur more easily in porcelain or glass cap-and-pzn insulators as a result of their shape. As a result of the ball and socket connection between the sheds of the cap-and-pin insulators (Figure 4.49 b), the damage caused by glass or porcelain fractures does not lead in each case to a collapse of the contact line and consequential damage is minimised. The creepage currents of up to 150 µA created on DC railways as a result of the climatic conditions and pollution lead to i:::orrosion damage at the cap connection fittings. The reduction of the diameter amounts to between 0,15 and 0,6 mm per year and requires the replacement of tunnel insulators every few years. Porcelain insulators are widely used clue to their high mechanical strength, chemical and heat resistance and their favourable electrical properties and were manufactured mainly from quartz-porcelain until the 60s. A disadvantage of this material is its tendency towards vitrification and porosity during firing, ·which causes a reduction in strength. Caused by a variation in Lhe temperature expansion of the quartz grains and the melting phase smrounding them, internal stresses are created by the frequent ternpera.ture chang<'.S <~xp<~ri<~lln~d d11ring opcrntio11al 11sc, which in turn cau cause cracks
~±A Wear and ageing (Figure 14. 7 right) and sudden failure. The almnini'/1,rn, o:cide porcelain used today helps to avoid the described disadvantages and to achieve double or triple strength [14.9]. Ten1,pern,t'll,re changes also affect the ageing of the cement that cormccts the porcelain body to the end fittings manufactured from malleable cast iron and that must compensate the differing expansion properties of these materials. Sealants using Portland and sulphur cement are affected more severely than those manufactured from lead-o:ntimon alloy, but possess a greater resistance to higher temperatures, e.g. during short-circuits than lead. The 8ervice life o.f porcelain insulators without flashovers is estimated to be 30 to 40 years. Failures of glass insulators are determined by their greater sensitivity to arcing and temperature changes compared to porcelain. Increasingly popular plastic insulators are especially resistant to external influences such as vandalism. Wear caused by weathering and UV radiation occurs in dependence upon the surface material. Silicone materials have shown themselves to be especially robust and long-lived. They simultaneously display hydrophobic properties and have been in use for approximately 20 years. They permit a reduction of the creepage paths, which has however not yet been taken into consideration in the standards. Since composite insulators materials, their wear properties are determined primarily by the endurance of the bonding between the glass fibre reinforced rod, the fastening fittings and the surface layer. Unstable bonding materials used for the attachment of the shields to glass fibre reinforced plastic rods and fittings cannot prevent the penetration of moisture into the intermediate spaces, and thus corrosion and internal flashovers. Positive experience has been gathered over the last 20 years with glass fibre reinforced plastic cantilevers in urban mass transit installations. The resins used to bond the glass fibres are subject to ageing caused by weathering in the form of alternating moisture and drying of the surface combined with UV radiation. As a result, the resin layers are eroded and glass fibres become exposed. The penetration depth over a period of 50 years is estimated to be only fe-w tenths of a millimetre [14.10] and therefore influences the strength minimally. This process can be retarded, for example, by applying a synthetic fabric close to the surface with a thicker resin layer.
14.4. 7
Disconnectors and section insulators
The pole disconnectors and their drives employed on electric railways must withstand several thousand switching operations over decades of outdoor operation. Wear occurs on the linkages, contact surfaces and arcing horns as well as ageing of the lubricating and contact greases. The adjustment and replacement of contact elements after frequent switching operations under load and renewal of the greases at regular intervals ensures a long service life of the equipment. The passage of pantographs over sect-ion insulators leads to wear of the runners due to increased contact forces, to loosening of the bolt connections and to comnnttiltion processes. The latter cause arcing, which is cldlectecl upw,uds by the arcing horns and then extinguished. The material erosion occurring at the arcing entry and exit points n)quires regular inspections and cornponcnt n)placcmcut, especially on DC railways.
_ _ _ _ _ _1_4 Erection and operation
750 - - - - - -
Maintenance
~---------,,-·-
I
Outage method
I
I
1
With minimal refurbishment
I
\
Preventive maintenace method
I
l
I
I
I
With maximum refurbishment
Routine maintenance at fixed intervals
Non-routine mainlenance depending on inspectioning results
l I
I
Fixed
Fixed
Fixed
operation
performance
duration
parameters
inspection schedule
l
l
l
-
I
l I
Repairing
I
Continuous inspections
l
I
Figure 14.8: Overview of maintenance methods.
14.5
Maintenance
14.5.1
Scope of maintance
Maintenance includes all measures according to EN 13 306 and DIN 31051 to preserve the planned status, to determine and evaluate the actual status and to restore the planned status of operating equipment and installations ..According to Figure 14.1 the terms servicing, inspection or repair are assigned to these steps. Servicing is not necessary on contact lines of modern design. Maintenance therefore consists of inspection and repair. According to [14.11], maintenance methods can be classified as shown in Figure 14.8. The outage method, by which the components are replaced only after the occurrence of damage, is unsuitable for overhead contact lines since they lack redundancy and have negative effects on train operations. Ro'/1,tine maintenance based on fixed cycles ensures high availability and exact planning of staff, machinery and track closures, but at high cost. DB and numerous other European railways have adopted non-routine maintenance depending on inspection res·u,lt.s. The overhead contact line diagnosis is performed on a pre-determined schedule, which t;-lkes experience, the importance of the lines and the condition of the systett1s into account. Servicing-free system elements an~ a prerequisite for this procedure. Bcpair work is performed dependent upon the inspection results and after failures.
14.5.2
Reliability
An overhead contact line installation is a rnrnpl<'X system from the aspect of relzalnhty and that possesses no n~d1111dancv for Ledl!lical and c\conornic rr'asons. As with othrr
14.5 Maintenance
to
Figure 14.9: Time axis of failure and repair of the overhead contact line.
lat lw1
ta tw
instant of failure instant of restart of operation
Table 14.4: Average function duration T 1oo in years between two failures of selected elements in the overhead contact lines. Element DB(a) RZD(b) Poles Supports Contact lines Section insulators DB German railways RZD Russian railways
17,6 2,8 1,5 21,5
10,5 2,4 1,5 30,4
Table 14.5: Average fault duration values for the overhead contact line system at DR and RZD (in brackets) for the years 1975-1977. Element Contact wire Steady arm Insulator Miscellaneous Contact line
jj8 h
ld00 km
5,3 (5,4) 3,3 (8,5) 4,4 (3,2) 4,2 (11,0) 4,2 (6,8)
5, 1 (2,4) 2.1 (1,7) 5,1 (1,6) 18,1 (5,5) 30,7 (11,2)
Ds100
0
operating equipment in the railway energy supply system, e.g. transformers and circuit breakers, it represents a regenerative object, i.e. its use does not cease at the instant of failure, but is only interrupted. It is repaired and recommences its duties. This situation is illustrated graphically in Figure 14.9. The overhead contact line installation is functional during the time period twi to tai+l, but not between tai and twi· The behaviour of the service life of individual components and the overhead contact line installation can be described as a random variable, with the exception of the contact wire. Significant parameters for the characterisation of the behaviour of the service life are the probability of failure-free work R(t) and the failure rate >.(t). The following applies: R(t) is the probability that the time of the failure T for the studied unit, e.g. 100 km contact line, does not occur within a studied period of service t. R(t) is also known as the survival probability. It is calculated in practice as follows 1 n R(t)~l No ~Sti (14.1)
In the equation, N 0 is the starting set of studied units and 8ti is the i-th fault. In this context, the term fault in transportation systems is identical with failure, i.e. the loss of the functionality. >.(t) is the probability of the failure of a studied unit within a tirne period of (t,t + 6.t) or failure rate, when the ;:;tudied unit has already had a sen ice life t. It is therefore the number of studied units that failed during the service period related to the number of studied units at the start of the service interval. [u other words, it is the mortality function f(t) related to the survival probability R(t). In accordance with the definition of the base variables of the reliability, the' fail'U,re rate is >-(t;) = -(dR/dt)/ R(t;) = f(t)/ R(t) (14.2) where f(t) is the tllortality function. For >.(t) = const., cquat.io11 (1-14) and f (t) /\e-,\t follow . Usi1tg the 11umber N1. of units at the start of the time' intcnal
14 Erection and operation
R(t) ,l(I)
-----R(t)
Figure 14.10: Development of failure rate >-(t) and probability of failure-free availibility R(t) for overhead contact lines with time.
~t, the empirical failure rate is calculated as A(t) "' (N, - N,+t,.t) / (N, · L':.t) "' St; / [ ( No -
~ Sti) L':.t]
(14.3)
Since contact line installations are repaired immediately after their failure, the failure rate per 100 km contact line or electrified tracks is determined in practice by means of the number of faults per year related to this contact line length. Statistically founded statements can be made for components and various designs of overhead contact lines, on the basis of numerous evaluations of contact line failures, that the respective failure rates are constant values (14.12, 14.13]. This statement does not apply to the contact wire in overhead contact line installations, which shows an increasing failure rate with increasing wear [14.12, 14.14]. A constant failure rate >-(t) = \ 0 however means that the mortality .f(t) is distributed exponentially. The following relationship between the survival probability R(t) and the failure rate applies for this practice-relevant case [14.15] R(t)
= e->-o t
(14.4)
whose trend can be seen in Figure 14.10. The failure causes for contact line.s and their components are extremely varied. A detailed analysis showed that for overhead contact line installations, the failure due to design .short-coming.s of the overhead contact line under real operating conditions lies between just three and a good five percent of the evaluated total failure rate for the overhead contact lines. E.1:ternal impacts on the overhead contact line have absolute dominance in the failure rates specified in Figure 14.16. These include influences derived from train operations such as defective pantographs, loading gauge violations and civil engineering, activities, climatic influences and railway crime. The stated failure rates should therefore be described as site-related fm}u,re rates. They are significantly higher than the failure rates for the overhead contact line hardware itself and are dependent upon location. There, the network or one railway compa11y can he viewed as a location, for example. If the failure ra.te is constant, tlt<~ll t lie fa.i Ime behaviour is not ckpcndent upon the
14.5 Maintenance
G) __;__ G)
Figure 14.11: State diagram for the contact line.
preceding loading history. The average fu:nctiunal life T. also known as the mean tirn,e between failures (lVITBF), is then
(H.5) The expected remaining service life iT is then also independent of the preceding sen-ice period. Therefore
(H.6) An expected value for the mean time between failures and the remaining service life of 100 km contact line of 83 days is calculated for DB using the data in Figure 14.16. Real observed values lie between a few hours and three years. The average mean time between failures does not permit a prediction of the next failure, however it allows sound planning of maintenance work. As can be recognised from Figure 14.11, the contact line is repaired after the loss of functionality. The downtime caused by the repair work includes the time period between the instant of occurrence of the failure and the restart of train operations. This variable D, also known as the mean time to repair, can be calculated starting from Figure 14.9
D
(1-L 7)
The mean time to repair includes the following significant time components mean duration from occurrence of the non-functionality until the start of measures to repair the ability to work or functionality, mean travelling time for the repair vehicles from the depot location to the fault location and mean working time for the removal of the non-functionality of the contact wire. It follows from the fault analysis that one half to two thirds of the total mean disturbance time is taken up by the working time to settle the fault. The mean time to repair is a random variable that can be described by the nornwl or Erlang-k distribution [14.16]. It can, as has been shown by the fault statistics of railway companies, be considered to be a constant parameter for a location in the defined context. Measured values of the mean time to repair for components and contact lines at two railway companies are contained in 1~1ble 14.5. 100 is the mean time t,·, repair related to 100 km contact line. The real duration of a fault varies between approximately five minutes and more than fifty hours. Function and organisation dependent downtimes are uot included in the mean time to repair.
754
-~---··
-·
14 Erection and operation
---· --·-------····-
The\ i11v
= 1/ D
(14.8)
The relw,/i'ility model::; cited by Markov [14.17, 14.18] are suitable for the description of the properties or renewable systems. The system states are defined by means of nodes and the relationships by directional graphs with corresponding transition rates (Figure 14.11). Two states are applicable for a contact wire system: Z0 contact wire is functional, Z 1 = contact wire has failed; The transition between the stated are given by the failure rate ,\ and the above mentioned correction rate µ. The state diagram can thus be drnwn as shown in Figure 14.11. The probability P0 is applicable for the state Z 0 and P1 for Z 1 . The following differential equation system can thus be stated for the description of the states:
P~(t) ) ( P{ (t)
(
- ,\ ,\
/L ) ( Po (t) ) -p Pi(t)
(14.9)
For the probability that the considered system is functional is obtained as the solution of (14.9)
Po(t) = µ/(µ,
+ ,\) + ,\/((µ, + ,\) · e(H;L)t)
.. -cl(t)
(14.10)
In (14.10) A(t) is the availability, which gives the probability that the contact line can completely fulfil its tasks under defined conditions at an arbitrary point in time. The constant availability A 0 is sufficiently accurate to characterise the failure behaviour for railway energy supply systems. The constant long-term availability for contact wires in electric railways is achieved approximately 24 h after commissioning. After that, it applies (14.11)
It rc~sults from equations(14.5), (14.7) and (14.10) Ao
(14.12)
T/(T+D)
Example:
Calculate the availability An: ,\ = 2/(100 km, a) D 10 h · 100 km = 10 h - 100 km , a/8760 It JL = 8760/(10 h 100 km) = 876/100 km a, Tlw constant availability follows from this to b(~
All= 876/(876
+ 2)
876/878
This means that the ovc)rh<)ad line is
100 km , a/876
= 0,99772
110(,
availahk
f01
l - 0,99772
per ,Y<)ar on the considered kng,th of cm!! net li1t<\ kilm11drcs.
0,00228 years or 20 hours
14.5 Mainte11a11ce -·. ------ ---~--·-- ----~ --------
755
The failure rates for ovcrlwad <·
14.5.3
Diagnostics
Contact line diagnostics according to [14.11] is understood to determine and rnwlYse of the state of a c:onta.ct line system on the basis of measurable or externally recog11isable properties, as far as possible without significantly influencing train operations. f ts objective is to reduce the cost for necessary maintenance work and to perform this at the correct time, wlule making full use of the remaining service life of the cquiplll('lll and ·with minimal impact on train op<)tations. Diagnostics are the basis for the trn11sition frorn rigid maintenance cycles to torulition-related rna:intenance alreaclv cm 11 pl, ·t <'
14 Erection and operation
156
Table 14.6: Schedule frn· the inspc~ction of overh<)ad contact lines at DB according to directive 997.o:J [14.G]. Type of inspection
Extent
Contact lill(\S
or
1st order mrn1ths
Check of condition Functional test
Zl Z2 Fl F2 F3 F4 F5
F6 F7
6 24
6s 12 12 24 72-12 I) 24 2 > when required
Cont.act lines of 2nd order lllOilths 24 24 12 12 12 24 72-12
6
l)
3)
when required
1) Determined on the basis of the number of pantograph passes and observed wear 2) Only for continuous main tracks 3) For v 2: 160 km/h
long-distance branch lines and urban railways, intersecting contact lines and head-span structures and also specially defined overhead contact lines, such as older types of design and especially endangered systerhs. All other overhead contact lines belong to the second order category. Checks of conditions serve to determine and assess the actual state of various overhead contact line components with the help of binoculars or simple measuring devices during line inspections on foot, without the necessity for switching measures or closures for operation. The check of condition Zl includes overhead contact line equipment, supports and tensioning devices. Check of condition Z2 includes all other contact line elements, such as feeder and other lines, cable termination seals, disconnectors, foundations, poles, head-span structures, railwa_,. earths, local control devices. El signals, warning signs and infringement of gauge. Damag<~d components and connectors, pollution, corrosion and the temperature dependent position of the contact lines, etc. are recorded. Functional tests cover the fu!lctio11 of the overhead contact line/pantograph system \.vith the aid of inspection or measurement vehicles. It includes mainly: Test Fl: Determinatioll of the 11osdum, of inter·secting contact wires at high-speed applying a. contact fore<' F.~tat IGO N. Test F2: Deterrnillatioll ()r tlw contact w1:re stagger position, the inclination of the registration anns alld st('ady arms and the position of darnps to avoid pantograph strikes with v S ,l() k111/lt awl F~tat = lGO :\. Test F:1: Detc\rn1illatioll or Lil<' con/,ar:/. w1.tc height at critical positiolls, e.g. at cont.act wire height rcd1wtio11s bdow :-:i,10 111 and at railway crossings with contact wire heights aL Lhc pi1sit io11 i11 still air hdmr 5,75 111. Test F4: Hcvi<)W or 1111,1.1111:11,m dcc!.ru uJ clearn:nces betwe<~11 the m·t rhc~ad contact 1
"
----
14.5 IVIai11tenance
Maintenance
Condition check
Full inspection
Z1: Contact lines F1 Contact wires aP1 · After short- From locality, · F2 stagger circuit from ladder or Z2 : FunctIonat aP2: After 20 from pole test of other F3 Height components .. non-localised posItIon short-circuits F4 · Clearance to live compaP3: After special onents events F5: Wear aP4: Arter accumF6: Dynamic F? Behaviour of pantograph
Fault removal 11 Correction of 12 Removal of functional faults that defects could reduce functionality
13· Removal of all defects that were identified dur,ng inspections
ulation of fault locations
Figure 14.12: Organisation of the overhead contact line corrective maintenance at DB.
line and bridges and tunnels with Fstat 250 N after disconnection and earthing. Test F5: Visual e:z:amination of the contact wire over its entire length and measurement of the contact wire thickness at the locations along a tensioning section suspected of having the greatest wear. Determination of the sequeuce for check measurements dependent upon the number of pantograph passes and the ,vear. Test F6: Testi,ng of the dynarnic behaviour of the oYerhead contact line system at the line speed and energised overhead line using the measurement car. Test F7: Observe the passage of a pantograph after reconstruction or repair of the overhead contact line. There are also condition and functional checks for special reasons, m addition to the planned diagnostic measures, known as extraordinary checks: Test aPl: Determination of the position of a short-circuit and examination of the overhead contact line within a narrow range of neighbouring supports and railway earths in the short-circuit path by means of an inspection on foot. Test aP2: E:ramination of the de-energised overhead contact luie with vehicles or ladders after 20 non--localisecl short-circuits. Test aP3: Inspection of the line on foot or per vehicle after special events, such as storms, extreme temperatures, icing, etc .. Test aP4: Determination of the contact wire po8'itiun at ,till al,'r, if accumulated contact force peaks and larger vertical accelerations of t lw pantograph were established during a functional test FG. The total du)ck includes a comprchensin_' ,isual inspection and the rncasmenient. or contact wire wear from vehicles or ladders. It is to be uu ric-d u11t after special l've11ts or dependent ou the train fr<~qlwncv, in periods staggcn'd c,Y<'r ar least 48 mouths for a
1 L! t:,n~n10I1
1<.10
and operation
Table 14. 7: Assignment of contact; wire thickness to categories of W
II III
Contact wire t,hick1wss Tii 100 (mm) Ri 120 (mm) 12,0 Lo 11,0 10,!) to 10,2 10,1 to 0,2
13,2 to 12,0 11,!) to 11,0 10,!) to 10,0
,/,
40 20 0
-20
Figure 14.13: Current connector in a thermovision photograph (left) and a normal photograph (right).
very high frequency, up to 10 years for low frequency, and including checks of condition Zl and Z2. An overview of all inspections and maintenance performed at DB is shown in Figure 14.12. The results of the diagnosis, such as contact un:re wear, contact wire stagger and contact forces, are elements of the operational handbook's modifications. These furthermore contain master cards with all characteristic data and their modifications as well as operating sheets with the inspection results, all damage, defects and repairs. lvlaintenance overviews serve the planning and checks of the necessary measures and also contain the fault positions and short-circuit locations. The compilation of the data is performed under consideration of the urgency of correctiw maintenance measures. If the indication device for the contact wire stagger responds in the range ?. 750 mm during functional test Fl, then the adjustment errors are to be corrected immediately, and in the range > 550 mm as soo11 as possible. The measured contact wire thickness are divided into the ca.tegorics according to Table 14. ,. A further diagnostic method for current c:arrving parts of energy supply systems is thermovzswn, \\·hic:h US(\S an infrared camera to make visible the increased temperature of damaged c:omporn:nts, such as poor electrical c011m~ctions and reduced cross sections of ,-vires and cables carrving electrical c111Te11t. co1rqmred to intact components [14.19]. The precondition for use of this tedrnology is th<: availahilit~· of defined currents, which can lw realised only with diffirnlty under electrical railway operation conditions. The :'-Jorw<·gian Main Line S<'n·ice: a ppli<'s 1Ii is nwl.l1od DB nwasures the operational
14.5 MaiHte!lance
Table 14.8: Classification of distnrba.ttce causes at DB. Overhead contact line defects
Internal railway impacts
External i1npacts
Manufacturing Insulators Material defects Power supply management Switchgear disturbaHces Protection tripping Voltage differences - Incorrect switching operatioHs Installation and maintenance Installation - Maintenance
Operation Adn~rse management - Railway operatioH accidents Othc'I reasons Traction vehicles - Defects of electric traction vehicles Non-observance of El signals Railway operation accidents Stopping in insulated overlaps -- Pantograph operation Defective wagons, inconect freight loadings - Other reasons Works at installations CiYil engineering work Work on supe1structures - Work on signalling systems
Third party impacts flashovers caused by animals - Climatic iHHuence8 Road vehicle8, constrnctiou machinery, tanlrn, etc. Third party railways Trees, branches C nauthorised persons Oil aH
current, which avoids operational impairment, but exposes weak points in the overhead contact line with greater difficulty. Figure H.13 illustrates the thermovision photograph of a current connector with a measuring current of 350 A. The clamp on the contact wire has heated to 63,3°C and therefore has a temperature 45 K higher than the contact wire and the current connector.
14.5.4
Statistical recording and analysis of faults
The stat1:stfral recording and analysis of material and operoting data, inspections and corrective rnaintenance, as well as irregularities and disturbances fonn an import.ant basis for planning mai11tena11ce a11d for the further development of overhead contact lines. Forms specified b:v the operator are used for recording of all important data related to a fault, such as location, affoctecl system components, assig11cd staff, time of the occurrence, the arrival of the maintenance team and the restoration of electric train operations. The fo:11,l/; Tepol'ts an~ distributed to specified clcpmtmc11ts depending upon the type of fault within defiiwd time limits and are included in the operational statistics. DB specifics the class1Jic:alion of dist'/1,dJU nces shown in Table' 14.8 for the recording of fault causes. Comparisons bctwcn1 the m<'rh<~ad c-011!.act line system statistics and their a11alysis for individ11al railway <·mupanies is onh condit :unally possible due to the different methods applied to nmi11tcu,u1t<' aud statisti<"al 1c>cordi11g. It was rlterdorc 011lv possible to co111parc a limited sd<~c·t.iou of data on the operational statistics of DB and the HZD iu Table 1°Ul.
14 Erection and operation
tl>U
Table 14.9: Selected data related to operational statistics during 1995. Parameter - Electrified li11e km - Electrified track km - Proportio11 of electrified lines iu network -- Proportion of electric traction related to transport volume Electrical energy consumption in MWh per track km - Contact line disturbances per 100 track km with trai11 delays, total - Portion caused by internal effect of electric traction - Portion due to external impacts - Number of damage cases to overhead contact line per 106 traction vehicle km Number of short-circuits per 100 track km Portion persistent short-circuits - Self-breakage of insulators per 1000 track km - Failure of fittings per 1000 track km Labour force for maintenance of overhead contact line, staff members per 100 track km
DB
RZD
17125 1) 44 809 1 ) 42,9 83,7 188 1,93 0,42 1,51 1 ,09
39100 91250 44,6 74,3 299 1,12 0,62 0,50 1,02
34 1,07 (3,2 %) 0,98 0,20 4,4
55 2 ) 1,46 1,72 10,8
1) Without urban transportation systems in Hamburg and Berlin 2) Only AC
11111
Delay minutes
Disturbance events 1,2%
Network - overhead contact line division
~ Network c}vil engineering and signalling division ~ Other disturbances / third party impacts
!ml! Dangerous events in
39,5%
operations
~ Other divisions (traction, civil engineering, etc)
Figure 14.14: Classification of technical train operation disturbances at DB during 1995. With damage to equipment and more than 1O min delay
Total
11111 Manufacturing defects ~ II Installation and maintenance ~defects
3,0% 10,2% 3,2%
~
Ill Operational management errors
r-7
IV B Network - Civil engineering
~ in overhead contact line network
6,1%
8,0%
53,4%
44 ,9%
L___l and signalling division ~
IV C Other divisions
~ (traction, work shops, etc)
~ IV D Third party impacts
Figure 14.15: Classification of disturbances m overhead contact line installations at DB listed for responsible parties.
14.5 Maintenance
6,5 6
b,5
- -
761
---------
Total number of all disturbances (l+ll+lll+IV) Number of disturbances with damage and delays(I +II+ Ill+ IV) Total number of all disturbances(l+ll+III) Number of disturbances with damage and delays (1+11+111)
5
4,67
4,5
13,: •
3
Z
2
Manufacturing defects
_J7_
s - ,-1~ i
-g:::, 2,5
r-1._J
--~-
1,5
I
l+ll+lll+IV
~-I
- ~--.__r-, __
t_..,I
II Installation and maintenance defects Ill Operational management errors in overhead contact line network -----193 ' IV External impacts
L-l.
1;1_~_11_+111 _
~~ ~
• 0 .7 7
-~----~---- 0,42
0 -+---+----+---+--+---+---+----+-1------i-t---+---+---+
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 Year--
Figure 14.16: Disturbances on overhead contact lines per 100 track kilometres, up to 89 West Germany, from 1990 combined with East Germany.
Figure 14.14 shows clearly using DB statistics that the overhead contact line system plays only a min01 role in the total number of faults, but a significantly larger role in the causes of time delays. The reason for this can be found in the lack of redun(iancy. This allows the conclusion that high quality, reliable owrhead contact lines are an essential prerequisite for punctuality in train operations. The subdivision into the classification of all faults, and the classification into groups responsible for causing damage to the overhead contact line system at DB and delays longer than 10 minutes during 1995 is contained in Figure 14.15. The development of overhead contact line disturbances at DB between 1976 and 1995 can be seen in Figure 14.16. This diagram clearly shows the increased number of disturbances resulting frorn the combination of the DB and DR overhead contact line statistics and the almost hurricane-like storms experienced during 1990. 'I'he number of disturbances with damag() and delays could be reduced continuously. The defects accountable to manufacturing, installation, maintenance and operational management have a very small scope in comparison to other railway companies.
14.5.5
Corrective 1naintenance
DB subdivides
·111.ainlenancc depending on the main ohj('ctive into fault repairs, individual repair aud full repair. Fa'/1,lt repair comprises thf• irn1tiediate restoration of the overhead contilct line to function and the removal of safetv r<'lcvant defects clet<\c·ted during iuspcctio1ts (jther completely or as far as absolntf'lv uccessary in order to avoid long delays oft 1ai11s . The mdivid'/1,al .,,epafrs serve to c()nect ddects that could l<'.;-Vl to an irnpairn1c1ll o!' the fuuctio!lality, P. g. replace!lwnt of cla111ps a.ft(~r glow-out . They are perfornwd during pre-planrn'cl work depl0Yt11('!lts a!ld c•xteud the time period 1111!.il Lite next. full i11spc
14 Erection and operation
Cmnplete correchve 111,aintena:nce contains the removal of all defocts observed during preceding inspections and examinations. It requires a long-term planning, co-ordination ,rith other activities on a line and a reinforced staff deployment. It. should be combined \\·ith a full inspection for economic reasons. The correction of defects in the adjustment of a contact line is preferably performed at positions where the contact wire wear is minor and offers the greatest benefit. If this appears not to be meaningful in case of contact wires in wear category III, check measurements should be made to anticipate violations of minimum limit values. O,·erhead contact line disturbances can be avoided by the timely removal of branches and bushes within a distance of 2,5 m from poles and lines. The partial renewal of overhead contact line components requires special techniques, under consideration of available track closure times and installation tools. Contact wire replacement commences with the release of the contact wire from the termination and its coiling onto an empty drum. The new contact wire is then strung to the tensioning device in place of the old one and fastened. The release from and the clamping onto the droppers and steady arms and the coiling and unwinding of the old and the new contact wires, respectively under pre-tensioning, can be performed simultaneously with the help of a common drum wagon. Wheel tensioning devices and steady arms are secured provisionally using installation aids. The replacement of a contact wire requires approximately 1,5 h for a tensioning section. During the replacement of a messenger wire, which is only necessary in case of steel or steel-copper conductors, the new messenger wire is drawn without or with little pre-tensioning and attached provisionally to the old messenger wire. The release of the old messenger wire and the connection of the new one to the supports, droppers and stitch wires follow this. The old messenger wire is finally coiled onto a drum and the contact line adjusted. The replacement of mechanically stressed components such as clamps, insulators, cantilevers and bolt-mounted poles first requires the alleviation of the load by means of installation equipment or aids. The replacement and loading of the new components can then follow. New head-span structures and embedded poles can usually be installed adjacent to the existing units and the loads then transferred. Subsequent adjustment and the removal of the old parts complete the work. Partial renewals are always costly and impair train operations as a result of the necessary track closures. They can be avoided or reduced to a minimum by employing long-hued components and high-quality overhead contact lines.
14.6
Recycling and disposal
14.6.1
Dismantling
The most commou case of partial clz.,rnantlin_q oc:cms during the replacement of the coutact wire clesnilwd in cla.t1sc) 14.G.G,
--
14. 7 Equipm<:nt fot inst.allat.iou aud maintenance
7G3
Compld,<~ rcucwal of the system, or the terminatiou of electric train opmations on individual liucs, n!quircs the co111pletc rernoval of the overhead c011,tac:t line. For rout.act lines, the c
14.6.2
Suitable preparation and disposal of materials for recycling
The dismantled components are processed in suitable workshops, dependent upon the recycling method. This includes suitable disposal and separation of the different materials and the cutting of metals to the lengths specified by the metal mills. The disposal of the individual components can be divided into the follmving categories: Re'U,.se at the same level: Steel from poles and cantilevers, non-alloyed copper from contact wires and clamps and the alloyed contact wire RiS, all belong to the materials that can be reused for the manufacture of the same components, after melting clown and appropriate preparation. Re'U,se at a lower level: The following overhead contact line components can be reused at a lower level: CuMg AC contact wires and aluminium parts, - concrete poles and plastics. Depositing: \Norn porcelain and glass insulators are mostly deposited on a waste d'U,mp.
14. 7
Equip1nent for installation and maintenance
14.7.1
Tools and equip111ent
To complv with the requirement for qualified installation and maintenance of on:rheacl contact line syst<:~ms [14.2, 14.:3], specurl err11:i11·ment and special vehicles are necessary in addition to th<~ usual tools and vehicles, which permit correct, rapid and safe working. It is usual to use the same equipment for installation, inspection, maintenance and rc~pair. Simpie handling awl continuous operational availability during rough railvvay operations und<'r all vvcather conditions is essential for high a.vailabilitv. Corne 11.lonq,<; with fiat liuk articulatc)d chains (Figure 14.17) or steel ropes permit the conductor or win· <'nds t,() ])(' p1tllcd togd.l1er Com<' alo11gs can cdlC'viatt· the load 011 thf'
14 Erection and operation
. !',
Figure 14.17: Gall's flat link come along.
Figure 14.18: Conductor grip for anchoring conductors and wires (Siemens AG).
Figure 14.19: Crimping tool.
Figure 14.20: Checking that line is de-energised and installation of earthing aud shortcircui ting (kvice.
765
14 7 Eq11ipt1wnt, f
Figure 14.21: Wheeled ladders.
contact wire during the i11sertio11 of i11sulators and section insulators. Short steel rope sections with thimbles at each end, also known as slings, are used during the fixing of tensioning wheels, for example. Hooks and conductor grip clamps (Figure 14.18) anchor wires or steel ropes clurillg the exchange of insulators or complete supports. Contact wire and grip clamps attach come alongs to the contact wire. Special tools, such as mechanical manual crimping tools (Figure 14.19) or hydraulic high-press'are presses alternatively with electrical or mechanical drives, ,vhich can be used for conductor clamps or feeder clamps . are required for the attachment of compression clamps. A stitch wire tensioning d<'' ice is used to adjust the tensile force in stitch ·wires from 0 to 5 kN. Voltage testers indicatr the voltage in the o-verhead line. After ensuring that the line is de-energised, l>oth sides of the working area are protected each with one, or in the vicinit,· of a suhst.at.io11 each with two earthing and short-circuiting devices (Figure H.20). Sa,.fet:i; belts and prot.ed11'1' hd111.et.s are a prerequisite for accident-free workillg on the overhead contact line :-;, stern. To reach the installation positio11 of the crnnponents, simple, double, ext< 11dahl<· and wlu:elr:d ladders (Figure 14.21) of -1 to 12 Ill length are i11 use. Tlwv nrn lie lift.< d 011!0 a.!ld awav from the track quickly dmillg track closures. 1
1
14 Erecti()_11 a11d operation
Figure 14.22: Pile driving from track bed (left) and setting the concrete pole with the pile-driver (right).
14. 7.2
Special vehicles
The foundation type, pole type and foundation construction methods explained in clause 14.2 determine the equipment to be used. Excavators with special claws prepare the foundation pit for block foundations. Drilling machines are normally used to excavate earth for round foundations. Pollution of the stone ballast bed by the drilling depris is a disadvantage. E.1:plosive pile drivers install the piles (Figure 14.22). Vibration pile drivers can only be used conditionally due to a possible clanger to superstructures. Road mixers or concrete mi:z:ing trains transport the concrete to the foundation. Mobile mixers transported on flat wagons tip the concrete into the foundation pits from the track. They can however also be employed from a direct access road. Concrete mixing trains transport their aggregate materials with them, mix them ,,·ith cement and water directly on-site and transport the concrete over conveyor belts into the foundation pits. The deployment of counete mixing trains is expensive and is only !C:Onomically viable for the electrificatiou of long line sections with large quantities of concrete. Railway cranes are us<~d for setting poles from the track, or alternatively motorised road cranes (Figur<: 14.2:3). Both alternatives require the closure of the track. H elzcop/;ers cau be employ<\d to set poles, lay railway traction power lines or even string hecul-spa,n sl·nu:h1,res in large railway stations without hindering train operatious. vVeighiug th<' rnst.s of a hc"'.licoptcr deployment (Figure H 23 right) against those
-
14.7 Eq11ip_mc,nt,
for
inst.allatio11 and maintc,11a11ce
767
Figure 14.23: Pole installation using motorised crane (left) and helicopter (right).
for track closures for tra.ditional installation methods determines the use of the inost advantageous method for the respective project. Special installation vehicles are used for the installation of cross-span structures, overhead lines, raihvay traction power lines, switch lines and disconnectors. Road velu:cles with working platforms assist the installation of cwerhead contact lines for tram systems in inner city areas. The insulated platform also allows working under voltage (Figure H.24 left). \Vhen rail vehicles approach, it is possible to clear the working site quickly. Dual mode rail- and road vehicles can be used on mads and tracks. They can be used for the installation of overhead contact lines on both light rail transit systems and also on main line railways (Figure H.24 right). The,· also allmv overhead contact line work that could not be performed from vvheeled ladders. The small d'l/,al rnode rail- and road veh1,cle shom1 in Figure 14.2-1 right perrnits ,, ork frnm the raisc'd platform on components at a height of 7,6 m and at a distaun' of G,:3 rt1 from the track axis, without under-propping the vehicle. The heavy version of this , chicle increasc~s the radius of action to 12,::i m aboYe the top surface of the n1ils . Tl1is ,ehicle is appro,ed for maximum speeds up to 80 krn/h on railway tracks wit Ii Olll' hogic drivcu l>y a static hydraulic: gC'ar Such dmd 111od<' ,chiclc's ca11not IH' fully used on tl('\\ high-spccd lines sinc-e the railway crossings IH'<"('SS;try f"or their d(•plonnent ar0 not m ailahlc. Figme l-L:2S illustrates the uo11-p101)('ll<·d nn1'T!inul 1:011/w:/ lw1: ·1.nstallat·1.u·11 11·w1011 t, p<' F\[\\ of 013, which is drawn lo tli<' \\orking sit(' Ii\· a illstillL-1tio11 trni11 l()C(llllOliY<' thrtt 111ows it, Lo t!ic·1c
14 Erection and operation
Figure 14.24: Road installation vehicle with working platform (left) and dual mode rail-road vehicle (right).
according to the work progress. It possesses a lG,2 m long raised working platform and a swivelling lateral platform, which enables ·work to be performed on components situated 5 m from the track axis. Overhead line installation wagons, also known as drum wagons, [14.20) permit mechanised overhead contact line installation, as described in clause 14.2. Contact wires and messenger wires can be strung in a rapid, labour-saving and economical manner with the help of the machinery and equipment installed on the wagon. The overhead contact line installation wagon Series 575 (Figure 14.2G b) is equipped with bogies and can travel at a maximum speed of 120 km/h. The t,rn hydraulically controlled conductor lifting devices fitted to the front and rear faces permit the stringing of contact and messenger wires vvith a maximum extension height of 7,5 m abon~ the top surface of the rails. The drum holders to wind the wires and conductors in and out possess their own drives and a brake tha.t enables the contact wire or the messenger wire to be strung with consta,nt pre-tensioning. Between the drnm holders for running wire in and out and the\ lifting frames there is an additional dnm1 holder located on each side for the storage of replaceHwnt drums. A hydranlically drin~n crane simplifies the loading or relocation of the drums .--wd the positioning of 1no·11r:er 1wles. On-board lighting provides s11fficie11t illumination for 11ight work . All ll<'cessnry wires and conductors, also 8 m and 11 rn U'.1nporary poles, a,lso known as pio11e<'l poll's. cantilevers, insulators and fiLtings
14. 7 Equipment._['01 installation and rna]r~t'.~11~111_c.:~i_
a)
7G9
b)
c)
6
3
-
2
9
14
18
2
3
15 19
5
17
1800 1-·---------------'1~4~8~60~------------18660 19900
---
L -----.
.
"e=,
8
4
7
2250
2450
"':'"":·'""!"' ----~-~-:
*
CD CD
r---
;
.::::::.:.·:::::::;,
(\J
:
2450
- - - - - - - -...-i--------,-
2250
/' 10
1 - Lifting frame with wheel head
10 - Switchgear cubicle operation and control
2 - Drum holder with drive
11 Switchgear cubicle battery fuses and charger 12 Battery box
3 - Drum holder for spare drum 5 - Dresel-hydraulic unit
13 - Equipment box 14 - Railing
6 - Pioneer pole holders
15 - Oil container
4 - Crane
7 - Cubicle for lamps
16 - Oil cooler
8 - Equipment cubicle
17 - Holder for rolling truck
9 - Storage boxes
11 13 12 16
18 - Holder for ladder
19 - Holder for cantilevers
Figure 14.25: Contact wire installation wagon (a) and overhead contact line i1tstallation wagon type S75 of DB (h) and (<)
f
I l/
Figure 14.26: Multi-purpose vehicle with working platform type MZA of DB (left) and platform construction motor coach type TVT 701 of DB (right).
are continuously available on the drum wagon for deployments to owrhead contact line disturbances with severe damage. The self-propelled m'ulti-purpose vehicle with working platform type MZA of DB illustrated in Figure 14.26 left, is a useful alternative to the universal TVT 704 described below. This more economical and simply designed maintenance vehicle is suitable for conversion measures and especially for planned maintenance work. The 8,95 m long maintance car type MZA is more convenient and therefore more efficiently deployed in the cross-over areas of stations, where the use of the 22,4 m long maintance car type TVT causes problems due to the necessary track closures. The maximum speed is 80 km/h. Overhead contact line components can be reached at a distance up to 3,85 m from the track axis and 15 m above the top surface of the rails using the platform combustion motor coach type TVT 701/702 of DB (Figure 14.26 right) with a hydraulically raised and swivelled, 3,85 m long working platform with extendable ladders. The platform and extendable ladders can be controlled from a control panel located on the working platform. The maintance car type TVT ,01/702 of DB can transport up to 3,2 t of tools, equipment and material at a permitted maximum speed of 90 km/h. Double ladders, earthing and short-circuiting deYices. pulley lifting gear. hand drilling machines, spotlights, portable emergency po1Ner generators, cutting and ·welding torches, radio telephones, train radio equipment, loudspeaker s,·stems and fire extinguishers are carried as basic equipment. Diesel engines prmicle traction independently from the overhead contact line. An accessible roof surface including the 6.29 n1 long raised-s,Yin~lling fforking platform are essential for the deployment of the overhead rnntact li,,1e 1:n.spPCtwn '111,otor coach type ORT 708 of DB, both for rnaint,cn;rnc(! and repair work as m'll as Cor oYerhead contact line installation (Figme 14.27). Tlte maximum speed of 100 kill/Ii permits a rapid response to clistmbauces. T!ie rnaintenance car type T\'T ,0-1 of DB (Figure 14.27 right), with a 111axi11u1m sp<'ed of 1-10 km/h, has a 5,7 m long \\Orking platform aucl an ext<\udable h-1dd<'r. This ;-1llows th<' execution of work on on•rlwad conl,,-1,ct line
14. 7 E<1_uipmcnt. for installation and mainl,cmuH'.C
771
T
Figure 14.27: Overhead contact line inspection motor coach type ORT 708 of DB (left) and platform construction motor coach type TVT 704 of DB (right).
- ,,
Figure 14.28: Large raised working platform maintenance vehicle type HIOB 711 of DB (left) and small overhead contact line maintenance vehicle type IFO 703 of DB (right).
components at distances of up to 5,00 m from the track axis and at a height of up to 17,5 m above the top of rails [14.20]. The useful load of G t. is used for tools, equipment and material. The unin-rsal vehicles type OHT 708 and maintenance car type TVT 04 are used for installation work, inspections all Ill loug and l,G tll wide for tlw 1naiutc11a11n~ cm t_vpe HIOB and :Z.0 111 long attd l A m wid<' l"01 t.lw rnaintcnaucP nu tvpe fFO. l<'igtm' I 1.1D shows tli<' working rn11gl'. or t.h(' rnis<'d-swivl'lli 11g platJonns of hot h vehicles. 0
14 Erection and opera~~on
772 N N
N N
b)
0 N
0
~
N
~ ~
~ ~
-stN
0
~
0
2
4
6
8
10 12 14m
~-------~--~~~~r-r--1~ O
2
4
6
8
10 12 14m
Figure 14.29: Action radius of raised working platform for maintenance car type HIOB (a) and maintenance car type IFO (b).
Figure 14.30: Overhead contact line installation vehicle type OMF 1 of DB.
A pantograph type WBL 85 with individually suspended contact strips is provided for test purposes. The viewing cockpit permits the observation of the overhead contact line and recording with a video camera. The overhead contact line installation vehicle type OMF 1 of DB (Figure 14.30) is a further vehicle for the installation, maintenance and repair of owrhead contact lines. This vehicle reaches a maximum speed of 120 km/h. The cabin is designed on ergonomic principles and ha.s 5 rn wide loading bavs 011 both sides, which permit pre-assembled components to be loaded. The accessible roof platform is 8,9 m long and provides storage space for ma.terial and tools d ming tlw installation of the OV()rhead contact line. The working platform has a maximum raised height of 14,3 m and a lateral radius of 12,9 u1, A working cradle~ for a r<)ach of 21 Ill above the top :,urface of the rail and a maximum lateral extension of 18 mallows vvork to he perfonrnxl on systr.m components that arr. difficult to reach ..A cra1w arm with a load moment of 2-10 MNm, which can also he nsed to sd. poles, and a pantograph for ('.he<"king tlw co11tact liue geometrv,
773
·.,.
Figure 14.31: Basic vehicle MTW 100.017 for the mechanised reconstruction of overhead contact lines.
insulated for 25 kV and suited for earthing to the railway earth if necessary, complete the equipment on this universal vehicle. Messenger wire and contact wire replacement on railway lines with high traffic frequencies is only possible with the aid of mechanised processes. The technolog, for the removal and immediate renewal of the' contact line described in 14.2 requires the deployment of the overhead contact line reconstr'U,ction train type lVIT\iV 100 017. Track closure times of only 5,5 hours per contact line section are sufiicient if the work is wdl organised. The installation train consists of two independent units, each with its own drive, orw for the removal and the other for the installation of the overhead ccmtact line. The first installation unit r
1-1 Erection and operation
77-1
Figure 14.32: Telescopic mea- Figure 14.33: Measuring vehicle at DB. suring pole.
ing platform for the installation of the cantilevers, and the longitudinal distance from the last pole to the platform for the installation of the droppers. It is possible to travel through the overhead contact line section at maximum line speed after completing the installation work [14.21]. Figure 14.31 illustrates the basic vehicle type iVIT\,\/ 100.017.
14.7.3
Measuring and diagnostic equipment
The contact and messenger wires can lJ< checked during installation using dynarnorneters. Graduated rnle, telescopic pole (Figure 14.32) and optical plv,rnb are simple devices for the measurement of the contact wire height and stagger from the track, whereby the latter measurement can be nnried out while the installation is energised. Vehicles ·with rneasnn,ng panf;og'ro,7!11.s [1-L 22, 14. 23] assist the checks of the contact wire height and stagger. Additional rneasming instruments [14.2'"1] permit the measurement of the contact wire thickness and th11s the contact wire wear (see clause 9.4.:3). Contact forces can be measured with mod<,rn '/IIC/1,su'l"i'IUJ mrs. Figure 14.:33 illustrates such a vehicle as used by DB. Measuring pt i1H iples and design of the measuring pantograph are described in detail in da11se (). .12. Fig11n, Ll.34 shows a thermol'?.swn ckuu:e for measuring the v~mperatures of co1tdncting parts of tlw overhead conrnct line:. 1
14.8
Life cycle consideration
D< cisio11s for the: design and us<~ ol' installations an\ incn~asingly !lli-Hl! l>Y opera.tors not only on th<, basis of tlw initial in,·<'StttH'llt, hut nlso under considc1ation of t.lw Lota.I exp
1
·---
14.8 Lifo cyd<~ C(H!sidera.tion
775
Figure 14.34: Thennovision measuring device at JBV.
during the lifetime of a component are today lmo-wn as life cycle wsts (LCC). They permit an integrated economic viability examination. The physical, i.e. real expected service life of overhead contact lines for electric railways is high compared to other equipment. \,Vhile the service life of ,ehic:les lies between 7 and 25 years, the physical service life of overhead contact lines can be estimated to be between 20 and 70 years (clause 14.4). This long service life is an essential reason why LCC examinations were not known in the past. The sen ice life of contact lines is furthermore dependent upon the development of electrically hauled transport. It is infiuencecl by the long-term line and speed development. These reasons also support the view that overhead contact lines be anal.) sed more strictly in accordance with LCC. The life cycle costs include rnan'llfact'llri,1,g i'l1,vestme'f1,ts,
operating and opcrntor costs, rnaintenance cost8 and disposal costs (recycling). The individual costs can be seen in Figme 14.35. Objectiv<' comparisons of merhead contact lines are possible on the basis of life cycle costs. High qualit\ OV(\lh<'ad contact lines that arc rnore <':Xp<'nsiv<· to tw-rnufactm<' clisplav th(' b1 fat l ll<' low<'st lifr c_vcle costs during system comparisons. The contact wire is Lite W<\ar-iut.cnsivc <'lenient of an m<'th<'ad tout.act lin<'. whose S(!t-vice life has a decisive iuflu<'t1C-<) upou the life cyclP costs. Tl\(' r:1,dw.nr1e of /,/Ii: co·11.lad win: under O(l(\tatioual couditious is associated with high costs Tll<' rnntact \\'ire wear tlicrd<,rc lias great signifirn.11n' rm th<) !if<) cvde costs. Tl!(' 1clt i11g or tl1e condudm
1-1 Erp~·tion an~l operation
776
Development
Material
Design
Installation
Planning(project work)
Additional operational costs
Errection
Third party work
Manufacture
Energy Operation
Network losses Compensationequipment Auxiliary loads Staff
Staff Maintenance Material Preventive maintenance, Inspection, Corrective maintenance, Repair
Vehicles & equipment Additional operative worcoslsk Third party work
Disposal (recycling)
Metals
Steel Non-ferrous metals
Non-metals
Concrete Plastics Ceramics Glass
Figure 14.35: Elements of life cycle costs for owrhead contact line systems on electric railwa:,.s.
cross sections influences the energy losses and the quality of the supplied voltage for electric train operations. High reliability and simple repair of the overhead contact line system after a disturbance is of fundamental importance for the maintenance cost. Overhead lines whose components are durable and less sensiti,·e to vandalism, electrical flashovers, atmospheric affects, etc entail lower maintenance costs. They ,,·ill he operational for a longer period. It should also be taken into ac-count that failures c;:1.use not only repair costs, but also a series of con,,
777
14 . 9 JfofcrPllCCS
14.9
References
L4.1 Fisclwr, n.; KidHi11g, F.: Frcil<~it.1mgeu, Pla11u11g, fforcd1111111g, A11sfiilu1111g (Ove1head power lines, planning, analysis awl design). 4t;lt <\diti011. Springcr-Verlilg, B
Overhead contact line (see appendix 1).
14.7 Becker, K.; Rescl1, U.; Rukwiccl, A.; Zweig, B.-W.: Lebensdauermodellierung \ 011 Oberleitungen (Modelling of lik: cycle of overhead contact lines). In: Elektrische I3almen 94(1996)11, pp. 329 to 336. 14.8 Becker, K.; Resch, U.; Rulnvied. A.; Zweig, 13.-W.: Das VerschlciHvcrhalten dc1 Hegeloberleitung Re 250 unter den Bedingungen des Hochgeschwindigkeit.sschienenvmkehrs (Wear performance of the standard overhead contact line Re 250 under the conditions of a high-speed rail traffic:). In: DET ClaHern Annalen 120(1996)G, pp. 24-1 to 2Gl. 14.9 Liebenmurn, H.: Teclmischc Vorziigc vou Tonerdeporzellan for clit) Zuvmli1ssigkcit. vmt Hochspa1mungHisolatore11 (Tedmical advantages of aluminimu oxide porcdaiu 011 the reliability of high-voltage i11Hulators). In: Keramische ZcitHchrift 47(1995)0. pp. 461 to 4G4. 14.10 \VoU: S.: Untcrsuchung zttr E11t.wickl11ng eincs Oberlcit11ng.s.stiit.zp1111kt('.S uluw Isolatorcn (Development of an overhead rnntact; line supports without i11s11lators). Fac:hhodt.sclrnlc Wicsliad()ll, UJ!)(i. tlwsis for diplollta. 14. l l Zweig, 13.-\iV.: Eiu [kit.rag zm optimalcu Gcst.alt.uug d<'l Falirlt,1t.i011 of 1ww diaguostic lll<'Lltod.s and deYi<(·s). If!V "Fric•drid1 List.'' Dn'.scktt. I !)8-L di.sscTlat.ion LltcHis
Ti8
14 Erection aud orer~1ti£)Il
1112 Pw-;clrnw.1111, H.: En11it.t.l11ug dc\r J\us[;tllrat.c\ vo11 Fahrl
or
H 1:3 Scl1111idt;, P.: E1H:rgic:v<'rsorµ,11uµ, ekkLrisd1cr 1311.l111c11 (Power supplv of dc:ctrica.l railwn.ys). Vc~rlag trauspn:ss. Berlin, I 988. 141 '1 Wiisl;Jwfi; vV.: Bc!itrag z11111 Z11sa11u11
14.15 Fischer, K.: Zuverfassigkc,its- nnd Iustaudhaltungstheorie (Theory of reliability and maintenance). Verlag t.rnw,pwss, Bc,rlin, l!J84. 14.16 Hase, P.: Ein Beitrag zur Bestimmuug optimaler Instandhaltungsmethodeu fiir Baugruppen von Kettenwerksfahrleituugen unter besouderer Beriicksichtigung von Elementen der Zuverliissigkeits- und Erneuernugstheorie ( Contribution on the determination of optimum maintenance methods for components of overhead contact lines with specific application ofreliability and refurbishment theory). Dissertation thesis, HfV "Friedrich List" Dresden, 1979. 14.17 Koslow, B. A.; Uschakow, I. A.: Hanclbuch zur Berechnung der ZuverU-issigkeit fiir Ingenieure (Handbook on calculation of reliability for t~ngineers). Hanser-Verlag, Miinchen, 1979. 14.18 Kochs, H.-D.: Zuverfassigkeit elekt.rotcchnischer Anlagen (Reliability of electrotechuic:al installations). Springer-Verlag, Berlin/Heidel berg, 1984. 14.19 Petrausch, D.: Thermische Modellierung und Thermovision bei Fahrleitungsanlagen (Thermal modelling and thermo vision at overhead contact line installations). In: Elektrische Bahnen 88(1990)2, pp. 80 to 84.
14.20 Borgwardt, ff: Schienenfahr7,euge wr Olwrl(:it11ngse11tstornng und -instaucllmltung fiir die Deutsche Balm (Special rail vehicles for fault clearing and maintenance: at German Railway). In: Elektrische Bal11w11 (JiJ(19%)11/12. pp. 337 to 340 and pp. ;349 to 356 l·L21 Thyle11, S.; L1111
U.22 Wessel, Ch: Fa.hrlcit.1111gsi11st.andltalf.1111gsfal1rzc~11ge (Hail vchiclc!s for overlwad rnnt,ad line, rnaiutemwce). lu: Eldd.risc!te 13al11w11 !J0(Hl!J2)3, pp. 107 to 110. 1-L2:3 Miillnr, K.: Fa.hrlc,it.11ngsi11sLwdli,tlt.1111gsLd1r1/,<'ug<) l'iir clie HliitLisd1e Bal111 (Trn,cti1i11 vehicles for overhead c:011!.acL li1w 111c1i1tl.c\11a11n~ of HliiitisdH: Bairn). I!L Elckt.risd1e Balwc\11 9,J (19%)10. pp :HM to .lJO
14.9 Refornuc:es ------- ·---·------
779
14.24 Irsigler, J\/I.; Pe/;rovif;scl1, Fl.: Elcktrotcclmischer Mcsswagcn der Ost.crcichischc11 Buttclcsbahtt (Elc\drotcdmical mca.sming car of Austrian Federal Railway). In: Ekkt.rischc Balmcn 94(1996)10, pp. :HO to :n4.
780
______ 14 Erection and operation
Appendix 1: Star1dards and regulations Al.I. IEC Publications IEC
Year
Title
EN, prEN
Year
IEC 60034-1
1996
EN 60034-1
1998
IEC 60038 IEC 60050-811
1983 1991
IEC 60060-1
1989
IEC 60071-1
1993
EN 60071-1
1995
IEC 60071-2 IEC 60099 IEC 60112
1996 Series 1979
EN 60071-2 EN 60099
1997 Series
IEC 60129
1984
IEC 60146
1991
IEC 60168
1994
IEC 60204-11
2000
IEC 60305
1995
IEC 60383-1
1993
!EC cm:383-2
1D93
Rotating electrical machines - Part 1: Rating and performance IEC standard voltages International electroteclmical vocabulary; chapter 811: electric traction High-voltage test techniques; Part 1: general definitions and test requirements Insulation coordination; Part 1: definitions, principles and rules Insulation coordination; Part 2: Application guide Surge arrestor Method for determining the comparative and the proof tracking indices of solid insulating materials under moist conditions Alternating current disc:onnectors and earthing switches Semiconductor convert.ors; general requiremenLs and line-commutated convert.ors; Part 1-3: Transformers and reactors Test on indoor and autdoor post insulators of ceramie materials or glass fiir syst.Pms with nominale voltages greater than 1000 V Safety of machinery Electrical equipment of machines Part 11: Requirements for HV equipment for voltage above 1000 V a . c. or 1500 V d.c and not exeeding 36 kV Insulators for overhead lines with a nominal voltage above 1000 V - Ceramic or glass insulat01 units for a . c . systems Charact<)ristics of insulator units of the cap and pin type Insulators for overhead lines with a nominal voltage above 1000 V part. 1: Ceramic or glass insulator units for a.c. svste111s definitions, test. methods and acceptaHc
1998
EN 60129
1994
EN 60146
1993
EN 60168
l9D4
EN 60204-11
2000
EN 60305
1996
EN 60383-1
ID%
EN G038:3-2
EN 60,LJ:l
1DD8
782- - - - - - - - - - - - - - - - IEC IEC 60449
Year 1971
IEC 60479-2 IEC 60507
1987 1991
IEC 60529
2001
IEC 60587
1984
IEC 60652 IEC 60660
1997 1999
IEC 60664-1
1992
IEC 60672
Series
IEC 60721 IEC 60815
Series 1986
IEC 60826
1991
IEC 60865-1
1993
IEC 60889
1987
IEC IEC IEC IEC
1988 Series Series 1997
60913 60947 60952 61000-5-1
IEC 61024-1 IEC 61089
1990 1991
IEC 61230
1993
IEC 61109
1992
IEC 61302
1995
IEC 61325
1995
IEC 61952
2000
···-···-···
Appendix regulations -----~ ~ - - -I:- Standards - - - - - -and --" "----
Title EN, prEN Voltage bands for electrical installiatous of buildings Effects of current passing through the human body Artificial pollution tets on high-voltage insulators EN 60507 to be used on a.c . systems Degrees of protection provided by enclosures (IP EN 60529 code) Test met,hodes for evaluating resistance to tracking and erosion of electrical insulating materials used under severe ambient conditions Loading tests on overhead line towers Insulators Tests on indoor post insulators of or- EN 60660 ganic materials for systems with nominal voltage greater than 1000 V up to but not including 300 kV Insulation coordination for equipment within lowvoltage systems; part 1: principles, requirement and tests Specification for ceramic all([ glass insulating ma- EN 60672 terials Classification of environmental conditions EN 60721 Guide for the selection of insulators in respect of polluted conditions Loading and strength of overhead transmission lines Short-circuit currents Calculation of effects - EN 60865-1 Part 1: Definitions and calculation methods Hard drawn aluminium wire for overhead line con- EN 60889 ductors Electric traction overhead lines Low-voltage switchgear and controlgear EN 60947 Aircraft batteries EN 60952 Electromagnetic compatibility (EMC). Installation and mitigation guidelines . General considerations. Basic EMC publication Protection of structu1es against lightning prEN 61024-1 Round wire conc:PILtr ic lay over head electrical stranded conductors Live working - Portabl0 ('quipmeut for earthing or EN 60230 earthing and short-circuiting Composite insulatms for ovm'<' IO00 V; definitions, test methods ,rnd ,H C('pli111<<' ( 1 itPria
Year
1993 1991
1999
Series Series
1993 1997
Series Series
2000
1995
1995
1995
2000
A_l_lJ2~~ndix 1: Standards and regulations
78:3
Al.2. European Standards EN, prEN EN ISO l4Gl
Yc),u
ENV l9!Jl-2-4
19%
ENV 1993-1-1
1992
EN ISO 9001 EN 10002-1
2000 2001
EN 10025
1993
prEN EN 13306 EN 50082-2 1l
1997 2001 1995
EN 50110-1 EN 50110-2 EN 50119
1996 1996 2001
EN 50121-1 to 5 EN 50122-1
2000 1997
EN 50122-2
1998
EN 50123-1
1995
EN 50123-3
1995
EN 50123-4
1991)
EN 50123-5
1997
EN 50124-1
20()1
EN 50124-2
2001
prEN 50125-2
1998
EN 50126
1999
p1ENV 50127-1
1996
EN 50149
200 l
pr EN ,r;o 151
2000
EN50152-1
J997
1999
Titk Hot dip galvanized coatings 011 fabricated iron and stec,] articles Specifications awl test methods (ISO 1461:1999) Basis of dcsig11 aml acl.io11s 011 structmc>s part, 2- !: Actions on st.rucf,ures Wind act.io11s Euroc:oclc 3: Design of steel structures -- Part 1-1: Stc cl General 1uks for buildings Quality management systems Requirements (ISO 9001:2000) Metallic materials Tensile testing -- Part l: Met hod of test at ambient t.emperatme Hot rolled ptoducts of uon-alloy structural steels; tedrnic:al cldivery conditions Precast concrete masts and poles Mainte11ance terminology Electromagnetic compatibility Generic immunity staudard Part 2: Industrial environment Operation of electrical installations Operation of electrical installations (national annexes) Railway applications Fixed installations Electric traction overhead contact lines Railway applications - Electromagnetic compatibility Railway applications Fixed installations - Part 1: Protective provisions relating to electrical safety and earthing Railway applications Fixed installations Part 2: Protective provisions against the effects of stray currents caused by cLc. traction systems Railway applications - Fixed installations - D.C switchgear - Part 1: General Railway applications Fixed installations D.C. switchgear Part 3: Indoor cLc. clisconnectors and switch-disconnect.ors Railway applications Fixed installations - D.C switchgear Part -!: Out.door cl.c. in-line switch clisconnectors, disconnectors and d.c earthing switches Railway applications - Fixed installations D.C switchgear Part 5: Smge arresters and low voltage limiters for specific use in cl.c. systems Railway applications -- Insulation coordination Part l: Basic requirements; Clearances and creepage distances for all electrical and electronic equipment Railway applications Insulation coordination - Pait 2: Overvoltages and r0lated protection Bailway applications Fixed equipment -- Environmental conditions fot c)c111ipment Part 2: Fixed installations Bailway applications- The specification and ckmonstratior1 of Rdiabilitv. availability, maintainahilitv and safrt~· (RA!\IS) Bailwav applications · Guide to the specification of a guided transport svstt'!Il Pmt 1: General Haihrny applirnt.io11s Fixc'd installations; Electric I ta
1
I k\
Appendix 1: Standar~l_sand regulations
784 Year
E\", prEN E;-.i 50152-2
1997
Tit.I<\ Railway applications Fixed installations Particular requirement for switchgear Part 2: Single-phase disc0111wctors, earthing switches and switches with Um above 1 kV Railway applications - Rolling stock Protective provisions relating to electrical hazanls Protection against corrosiou by stray current ftom DC systems Railway applications - Supply voltages of traction $_\-stems Human exposure to electromagnetic fields Low frequency (0 Hz to 10 kHz) Power installations exceeding 1 kV AC Couductors for overhead lines Round \\·ires co11centric lay stranded conductors Railway applications Rolling stock - Pantographs: Characteristics and tests Part 1: Pantographs for main line ,·ehicles Railway applications - Rolling stock - Pantographs: Characteristics and tests - Part 1: Pantographs for metros and light rail vehicles Railway applications Current collection systems Validation of simulation of the dynamic interaction bet,,-een pantographs and overhead contact lines Overhead electrical lines exeeding AC 45 kV Railway applications - Fixed installations: Electric traction - Insulating synthetic rope assemblies for support of O\·erhead contact lines Information technology equipment - Immunity characteristics - Limits and methods of measurement
,LC.
EI\ 50153
1996
prEN 50162 EN 50163 E:'iV 50166-1 1l
2000 1995 1995
prEN 50179 EN 50182
1996 2001
EN 50206-1
1998
EN 50206-2
1999
prEN 50318
1999
prEN 50341-1 to 3 prEN 50345
2000 2000
EN 55024
1998
l) withdrawn
Al.3. UIC Publications CIC 505-1 CIC 505-4
CIC 505-5 UC 600 t:-IC 606-1 UC 606-2 UC 608 nc 191 nc 870
Kinematic gauge for powered units used on international services Effects of the application of kinematic gauges defined in -505 series on the positioning of structures in relation to the tracks, and the tracks in relation to each other Basic conditions common to leaflets 505-1 to 505-4 Electric traction with aerial contact line, 1981 Application of kinematic gauges to contact lines Installation of 25 kV or 60 Hz contact lines Pantographs on international services Methods for maintaining overhead contact lines Technical specification for grooved contact wires, 1987
Al.4. Other standards still valid in Germany DIN VDE DIN VDE 0100 DIN VD E O100-200 DIN VD E 0 100-410
Year Series 1998 1997
0101 0102 0105-103 0109-13
2000 1990 1999 1990
DIN DIN DIN DIN
VDE VDE VDE VDE
Title Erect.ion of power installations with rated voltages below 1000 V Electrical installations of buildings -- Part 200: Definitions Erection of power installations with nominal voltage up to 1000 V -Part 4: Protection for safety; Chapter -11: Protection against eler,tric shock Power installations exceeding 1 kV Short-circuit cmrPut - Current calc:ulation in tlnce-phase a.c:. systems Opc\1 ation of P!Pctrica.l power Pa.rticular wquirernents for railways lusulation coordination within kJ\\·-voltage systems; coordination of the tasks, insulation coordiuatio11, installation rnkis and protection against eb:tric shock (draft)
Appendix 1: Standarcls~t1~~-r~ulati_o_n_s_ _
DIN VDE DIN VDE 0110-1
Year 1997
DIN VDE 0115-1
2000
DIN VDE 0115-3 DIN VDE 0118-1
1995 1990
DIN VDE 0141
2000
DIN VDE 0150 DIN VDE 0210
1983 1985
DIN VDE 0216
1986
DIN VDE 0216-2
1992
Fittings for overhead and conductor rail equipment; electrical contact behaviour of current-carrying fittings under normal operating conditions (draJt)
DIN VDE 0228-1
1987
Proceedings in the case of interference on telecommunication installations by electric power installations; general
DIN VDE 0228-3
1988
DIN VDE 0228-4
1987
DIN VDE 228-6
1992
Proceedings in the case of interference on telecommunication installations by electric power installations; interference by alternating current traction systems Proceedings in the case of interference on telecommunication installations by electric power installations; interference by d.c. traction systems Interference on information technology equipment electrical and magnetic fields in the frequency range from Oto 10 kHz (draft)
DIN VDE 0441-1
1985
DIN VDE 0441-2
1982
DIN VDE 0441-100
1992
DIN VDE 0670 DIN VDE 0848 DIN VDE 0873-1
Series Series 1982
Title Insulation coordination for equipment within low-voltage systems Part 1: Principles, requirements and tests Railways General construction and safety requirements Part 1: Additional requirements (draft) Railways Particular requirements for stationary installation Erection of electrical installations in mines - Part 1: General requirements Earthing system for special power installations with nominal voltages above 1 kV Protection against corrosion due to stray currents of d.c. installation Planning and design of overhead power lines with rated voltages above 1 kV Fittings for overhead and conductor rail equipment; static mechanical behaviour; requirements and testing
Tests on insulators of organic material for systems with nominal alternating voltages greater than 1000 V; tests on materials Tests on insulators of organic material for systems with nominal voltages greater than 1000 V; tests on outdoor comosite insulators with fibre glass core Tests of composite insulators for a.c. overhead lines with a nominal voltage greater than 1000 V (draft) A.C. switchgear and control gear for voltages above 1 kV Safety in electrical, magnetic and electromagnetic fields i\!Ieasures against radio interference from electric utility plants and electric traction systems; radio interference from systems of 10 kV and above
Al.5. Product standards m force m Germany (a selection) DIN DIN 102.5-2 DIN 104.5-1 to 4
Year 1995 Series
Title Hot rolied 1-lwants -- Part 2: \Viele flange I-beams, IPB-serics; dimensions, massPs, sectional properties Coner ()tP, n\inforced and prcstressecl concrete structures
______ Appendix 1: Standards and regulations
DIN DIN 1055
Year Series
DIN DIN DIN DIN DIN
1990 Series 1991 1990 1980
4021 4022-1 to 3 4030-1 to 2 4094 4096
DIN 4113-2
1993
DIN 4228 DIN 5901 DIN 17122
1989 1995 1978
DIN DIN DIN DIN DIN
18800 31051 43138 43140 43141-1
Series 1985 1980 1975 1975
DIN DIN DIN DIN DIN
43147-1 to 3 43148 43155 43156 43167-1 to 3
Series 1986 1985 1978 1987
DIN 43174 DIN 43188
1970 1980
DIN DIN DIN DIN DIN DIN DIN
48200-1 48200-2 48200-7 48201-1 48201-2 48201-5 48203-1
1981 1981 1981 1981 1981 1981 1984
DIN 48203-2
1984
DIN 48203-5
1984
DIN 48203-11
1987
DIN 50142 DIN 83305-2
1982 1984
Title D<1sign loads for buildings; stored materials, building materials and structun-1.l members, dead load and angle of friction live loads, wind loads on structures unsusceptible to vilnation Soil; exploration by excavation and borings sampling Subsoil and groundwater Assesment of water, soil and gases for their aggressiveness to concrete Soil: exploration by penetration tests Subsoil; Vane testing; Dimensions of Apparatus, Mode of Operation. Evaluation Aluminium constructions under predominantly static loading; static analysis, structural design and execution of welded constructions (drawn) Precast concrete lattice towers masts and columns Flat bottom rails - Dimensions, sectional properties; steel grades Steel Conductor Contact Rails for Electric Traction; Technical Conditions of Delivery Structural steelwork; design and construction Physical assets maintenence; definitions and actions Flexible cables for overhead equipment and return current Contact wires; technical terms of delivery Grooved contact-wires for electric traction; dimensions and constant current load Electric traction; dropper clamps Wedge clamps for overhead equipment Clamp holders for overhead equipment Electric Traction; Conductor Rail; Dimensions and Characteristics Rod-type insulator for overhead contact lines for operating voltages up to 1000 V a.c. and 1500 V d.c. Pantographs for electric traction; directives for selection of dimensions Insulators for overhead equipment, 1000 V a.c./1500 V d.c.; mounting dimensions Copper wires for stranded conductors Bronze wires for stranded conductors Copper clad steel wires for stranded conductors Copper stranded conductors Bronze stranded conductors Aluminium stranded conductors Copper wires and copper stranded conductors; technical delivery conditions Wrought copper alloy (Bz) wires and conductors; technical delivery conditions Aluminium wires and aluminium stranded conductors; technical delivery conditions Wi1 es and stranded conductors; steel-reinforced aluminium stranded conductors; tedrnical delivery conditions Testing of meta.Ilic materials; Flat bending fatigue test Fibre ropc\s; vocabulary
Appendix 1: Standarclsand regulations--------·
787
Al.6. Rules and regulations set down by selected operators Al.6.1 Deutsche Bahn AG
DBAG
Al.6.1.1 Business sector directives (Geschaftsbereichsrichtlinien) 134 300 462
Building contract regulations Railway construction and operating regulations (EBD) dated 08.05.1967, Edition 1992 Operating of overhead contact. line network, principles
800.01 800.02
Clearance gauge and track spacing, standard gauge with overhead contact lines Design of railway installations; new lines
995
Substations for railway power supply
997.101 997.102 997.103 997.104 997.102 997.201
Overhead contact lines; general principles Overhead contact lines; planning and construction Overhead contact lines; work on overhead contact line, monitoring and acceptance Overhead contact lines; maintenance of overhead contact line installations Overhead contact lines, return current and railway earthing installations Overhead contact lines; principle rules for return current, earthing and equipotential bonding installations Overhead contact lines; planning return current installations Overhead contact lines; building return current installations Overhead contact lines; planning railway earthing installations Overhead contact lines; building railway earthing installations Overhead contact lines; planning and building equipotential bonding installations Overhead contact lines; return current conductor applications Overhead contact lines; special return current conductor provisions for high-speed railway lines Overhead contact lines; return current conductors and railway earthing in concrete structures Overhead contact lines; return current conductors and railway earthing for slab track Overhead contact lines; return current conductors and railway earthing on lines also used by DC railways Overhead contact lines; railway earth bonding of noise-reduction walls Overhead contact lines; railway earth bonding of roadway troughs on piers
997.202 997.203 997.204 997.205 997.206 997.221 997.222 997.223 997.224 997.225 997.241 997.242
Al.6.1.2 DB standardised designations for DB-specified standard overhead contact line designs The meaning of the drawing numbers will be explained using the following example: 4 Ebs 0L02.0l. The individual parts of the number are 4 : DIN A4 format Ebs : Plan symbol 01. : Main group number 02. : Sub-group number 0L : Serial number (counter)
Appendix 1: Standards and regulations
The main groups of the Ebs drawing index comprise:
01 : Basic drawings of overhead contact line 02 : Structural design and construction procedures 03 : Foundations 04 : Poles 05 : Supports 06 : Supports in head span structures 07 : Overhead contact lines, non-insulated overlaps, insulated overlaps, neutral sections 08 : Tensioning wheels. section insulators 09 : Mast-mounted clisconnectors, electrical switchgear drives, cable end sealing 10 : Current connections, switch cables, feeder clamps 11 : Head span suspension, head span structures 12 : Arrangement of overhead contact lines and supports at superstructurs, tunnels, service tracks of trains and containPr stations 13 : Insulators 14 : Signs, overhead contact line signals 15 : Earthing, return current conduction 16 : Feeder and booster lines 25 : Overhead contact line Re 330
Al.6.1.3 The drawing collections of the DR-M, which still apply to existing installations, encompass five sectors 21 and 22 23
: Railway traction energy supply, 16 2/3 Hz : Railway traction energy supply, direct current railways
24
: Overhead contact lines for direct current railways
25 26
: Overhead contact lines for alternating current railways : Maintenance of overhead contact lines for alternating current railways
This collection of drawings is subdivided into main groups and sub-groups, these being given serial numbers.
Al.6.2 Swiss Federal Railway - SBB Installation manual
OL6.l OL6.2
016.3
fully compensated contact lines (R-Fl), stations fully compensated contact lines (R-Fl), main lines fully compensated contact lines (R-Fl), tunnels
Al.6.3 Bern-Lotschberg-Simplon Railway BLS Manual
I
Manual
II
Contact lines with tension-compensated contact wire and fixed catenary wire, Design
1961 Fully-compensated contact lines for two-track refurbishment of the Frutigen-Brig line,
1978 Manual
III
Fully-comp0nsated contact lines for high-speed traffic, 1989
Al.6.3 Austrian federal railway - OBB EL 42 EL 43 EL 52
Official instructions concerning protective measures in high-voltage equipment Official instrnctions for protective earthing of contact lines a.ncl supply cables of singlephase AC railwa.vs Official instr 11ctions for the opr.rntion of electrical installations of r.lec:tric-traction main lines, local lines and con1wc:ting linc!s
P 40
Staff prntPct ion and accident prevention regulations
DB 720 DB 921
SupPrvision ,tnd 111onitoring of building and co11struction work Contact lin<' poks used by Ll1<• hstc·ncid1isdie Gunclesl>ahn
Appendix 1: Standards _and regulations
DB 922 DB 925 DB 926 DB 927 DB 926/4 DB 929 DB 945
BH 701 BH BH BH BH
730 906 906a 910
BH 919 BH 933 BH 934 BH 935 BH 937 BH 939
789
Measures carried out on contact. lines of the ()BB Ill mder to inn0.ase t.he pmrnit.ted maximum speed to 200 km/h Contact lines of the OBB, development and basic principl<\S Contact lines of the OBB, planning directives Rules on the drafting of designs, construction and execution plans for overhead cont.a.ct lines of the OBB Contact lines of the OBB, directives on the application of comprf'ssion and crimping technology in overhead line construction Earthing equipment for installations of the OBB, excluding 50 Hz svsterns Execution drawings for standard OBB overhead contact lines Volume 1 - overview drawings Volume 2 - drawings of individual parts (subdivided as stated in attachment) Conditions for tenders and special contract conditions of the OBB for the provision and execution of building and construction work General provisions for contracts on blasting work Technical specifications for contact line switchgear remote controls (three-wire operation) Technical specifications for contact line switchgear remote controls (five-wire operation) Particular specifications (delivery conditions, acceptance conditions) for reinforced concrete poles for contact line installations and reinforced concrete supports for switchgear Regulations for services and material supplies for the construction of railway traction energy supply cabling systems Particular specifications for the supply of tubes made of Al Zn 4,5 Mg 1 F 35 for cantilevers Particular specifications for the supply of grooved contact wires made of copper for OBB overhead contact line installations Particular specifications for the supply of cylindrical wires and stranded cables of copper or bronze for OBB overhead contact line installations Particular specifications for the supply of uncoated copper-clad steel wires and stranded cables for overhead contact lines and energy supply lines of the OBB General technical regulations for the construction of standard OBB overhead contact lines
Al.7.4 Australian Railways Transport Co1porntion in Victoria (splited up into priYat.e operater) Train Overhead Design Standards For The Rehabilitation of Existing Routes, 1997, Issue 3. Train Overhead Design Standards For The Rehabilitation of l'\ew Routes. 1997, Issue 5. Train Overhead Design St.andanls For The Const.ruction Of New Railwm Overhead Works, 1997, Issue 3. Australian Standard AS 4292.2-1997, Railway Safety i\Ianagement, Part2: Track, civil and electrical infrastructure. !Vestra:il (\Vest Australian Government Railways) Document. No . 819-800-001: The Design, Supply Const met.ion and Commissioning Of 25 kV Traction Ovc\thead Catenary Equipment.. Part "A'': Stamlard Specification. Part ·'I3" .: Detailed Ivlat.crial Specification
j Appendix 1: Standards and regulations
790
Al .8 Regulations on urban mass transit BOStrab VDV 500 1l VDV 501 VDV 510 VDV 515 VDV 530 VDV 551 1) VDV
1981
German Federal Regulations on th(-\ construction and operation of light rail transit systems (BOStrab) 1991 Earthing provisions for DC traction systems with examples of operation 1993 Reduction of the corrosion danger due to stray currents in tunnels of DC traction systems with return current via running rails 1992 Electrical power installations in tunnels of DC traction systems 1993 Cables for the traction power supply of DC traction systems and trolleybuses with nominal voltages up to 750 V 1990 Maintenance of power supply, contact line and lighting installations 1996 Poles and Pole foundations for overhead contact lines Publications (recommendations) of the Association of German Transport Undertaking;; (Verband Deutscher Verkehrsunternehmen), Kamenekerstrasse 37 to 39, 50672 Cologne
Appendix 2: Frequently used abbreviations AC ACLR ACLRT ACLT AEIF AENS AL ASD AVE b BLS BS BS C C
CA CAD CB CCITT
ccss CENELEC CIR-ELKE CIR-NET CLD CP CP
cw CWH CWHcxist DB DBD DC DCF77 DFL DIN DMM DMVT DMVT DH
Alternating Current Automatic overhead contact line reclosing Automatic overhead contact line reverse voltage testing Automatic overhead contact line testing European Association for Railway Interoperability Automatic emergency neutral section Additionel lenght Automatic synchronising device Alta Velocidad Espanola stagger of contact wire at support Bern-Lotschberg-Simplon Railway in Switzerland Blade start British Standard Converter Stagger at midspan Catenary wire Computer aided design Circuit breaker Consultative Committee International Telegraph and Telephone Central converter substation European Committee for Electroteclmical Standardization Computer integrated railroading to increase the performance of heavy-duty network Computer Integrated Railroading-Network Contact line disc:onnector Coupling post Caminhos de Ferro Portugueses Contact wire Contact wire height Contact wire height exist Deutsche Bahn AG (Gu"man Railway) DB-directive Direct Current Radio clock Low-duty driven probe Deutsche I1td11stricnorm Digital mcL<\r monitoring and procc~ssi11g Digital met.er value transfer Digital met.<\J valtH~ Lransfor Dm1Lscl1<~ !1cid1slmlu1 (former East. Ccrnt,tll Railway)
792
DSS DYN e e
EB EFS Elrn EL EMS EN eperm
F FEM FH
FL fp FS G GC CPS GW
ewe GWS HcA Hew HIOB ICE ICT IEC IFO IN frail
IRPA IT ftrc
JBV JPEast JPP JR K L LCC LCU lnmin LH LSWH
_ _ _ _ _ ~J~pen~lix 2: Frequently used abbreviations
Decentra.l converter :-mhstation Blow off of contact wire Distance between foundation surface and (;op of rail ElektriHche Balmen (magazine for electric railways in Germany) Electronic overhead contact line protection DB-substation drawings handbook Signal for electric railways in Germany Emergency neutral section European Standard Contact wire stagger permitted Force Finite-Elemente Method Horizontal force Parallel feeder line Pre-sag Ferrovie dello State Italiane Load Gabarit C Global positioning system Large type of substation with workshop Gateway centre Gateway substation Catenary wire tensile force Contact wire tensile force Working platform maintenance car Intercity Express Train in Germany Intercity Tilting Train in Germany International Eletrotechnical Commission Overhead contact line mainteneance car Integrated network Rail current International Radiation Protection Association Isolating transformer Traction current Jernbaneverket Norge East japan Railway Joint power plan Japanese Railway Small type of substation without workshop Length life cycle costs Local control unit Minimal dropper length Headroom of Bridge Lower cross-span wire height Transition length
793
rn' MCC
MZA NCC OBB OEB OHL OHL ONAN OS PC PCS PE
PH PLCT
pp PS R R RC RCN Re REB RENFE RL RS RSM RSS
SCADA
sec
SG SG SH
SM SNCB SNCF SP SPT
ss SSH TBB TC
TCC TE TGV
TLSP TP
Mass per unit master control centre Multi-purpose maintenance car with working platJonu Network command centres Operating bus bar October Railway in Russia Overhead contact Linc Overhead contact line Operational Hignals Point centre Process computing syHtem Point end Point heating Transmission device carrier frequency modulators Power plant Point Htart Rectifier Radius Return conductor line Remote control nodes Overhead contact line type in Germany Russian railways Reel Nacional de los ferrocariles Espanoles Reinforcing line Railway station Remote control module Rectifier substation Supervisory control and data aquisition system Satellite control centres Synchronous generator Switch gear System height Synchronous motor Societe National des Chemins de Fer Beiges Societe National des Chemins de Fer Franca.is Switching post Standard penetrntio:1 test Substation Stn1ctural support height TcHt bus bar Telecommunication device TrausmiHsion control ceuter Trnnsitiou curve end 'frain Grand ViteHse in France 'l\actiou powc)r supply line DisLalln~ bdwc<)ll track C<)ntre aud pole frollt face
____________ Appendix 2: Frequently used abbreviations
TPL TPLH TR TS TU
urc Uss V
VDE
WT Z1 Z1
ZT Ztrain
Top of Pole Distance between upper swivel bracket and suspension or termination of traction power lines Top of rail Transition curve start Traction unit Union International des Chemins de Fer Substation voltage Speed Verband Deutscher Elektriker AC-telegraphy Line impedance Rail impedance Transition impedance track-earth T\·ain impedance
- - - - - - - - - - - - - - - - - - ----------------~=-
Ir1dex AC
25 kV 50 Hz substatiou 62 50 Hz single-phase traction network 40 50 Hz traction power system 33 telegraphy 59 acceleration due to gravity 220 sensor 473 acceptance procedure 729 accessible voltage 621, 624, 628, 630 accident prevention training 740 accumulation of ice 86 across track feeder 315 active protective measures 657 additional ice load 235 load 219 resistance 629 adjustable height design 429 adjustment diagram 301 plan 311 work 735 aerodynamic coefficient of resistance 231 component of the force 4 75 contact force 92 correction 468 drag factor 240 force 468, 485, 510 resistance 92 force 92 uplift force 475 wind pressme 343 ageing 741 of connectors 744 aggressive dust 86 air gap section insulation 148 airborne substance 86 alloy containing silver 598 alternating
current :n railway 629 lateral diRplacemcnf; 267 magnetic field 712 aluminium -steel composite conductor rail 125 rail 126 cantilever 182, 744 cast alloy 182 component 744 composite conductor rail 127, 590 conductor 114 hinged cantilever 199 oxide porcelain 749 ambient temperatme 71, 582 ampacity 579 amplification coefficient 450, 452, 490, 494, 508 factor 471 amplitude-frequency spectrum 706, 707 anchor foundation 395 angular frequency 518 annual mean load 565 anodic area 655 current 653 reaction 657 anti -climbing device 99 -symmetrical oscillation 451 apparent mass 501, 511 arc duration 467 quantity 467 suppression coil 47 arcmg 511 an)a used for installation lO~l arithmetic mean °!7G articulated lorry 77 assessing the quality of current trattsmission 4GG
Index
796--
asynchronous-synchronom; converter :38 at-grade section 683 attenuation constant 646 audible noise 466 audio frequency 309 track circuit 689 track release circuit 691 Austrian Federal Railway 204 auto-transformer 42, 676 section 626 system G72 automatic compensation 118 dropping device 511 overhead contact line re-closing 54 reverse polarity testing 54 testing 54, 616 synchronising device 55 tensioning device 110 automatically tensioned overhead contact line 8G automation component 53 auxiliary catenary wire 122, 210, 453 circuit group 58 power 87 supply 50 supply at coupling post 51 availability 754 of the traction power supply 608 of train operations 755 average functional life 753 axle counting equipment 692 shunt sensing 691 back-up protection 610, 614 provision 609 ballast resistance 534 bare conductive strip 684 basic circuit 553 section disconnect.or GG8 bearing capacity 382 behaviour of insulators wit.h ti11w IH\tHling stiffness 232
747
bi-metal copper clad sheet 182 bi-metal copper-dad steel conductor 744 bird protection 103 block -type substation 44, 45, G3 and pulley arrangement 119 foundation with steps 388 blow-off 240 bonding cable 128 booster transformer 677 system G72 bore hole logs 381 both rails insulated (:i89 bouncing contact strip 684 boundary distance 655 bracing force 367 braking current 621 bridge amplifier 471 drawing 264 bridle wire 116, 117 broken contact wire 663 bus bar disconnect.or 46 protection 51 bypass feeder 349 disconnector 55 7 line 110 c-value 242, 2G2 cable in parallel 677 layout plan 259, 264 potheads sealings 171 cant deficiency 76 canted track centre line 2DO cantilever 345, 352 across several tracks U5, 346 calculation program :H 8 design 397 drag 228 length calculation 259 mounting 731 type :n8
cap-and-pin insulator 176 capable of high performance 69 capacitance 538 per unit length 536 capacitive interference 635, 717 capacity characteristic 609 charge 94 carbon collector strip 90, 113, 506 cardiac pacemaker 722 carries drop 346 casting-rolling process 598 catenary curve 232 catenary wire 109, 112, 118, 762 clamp 185, 346 pulley suspension 189 support 160 clamp 186 support clamp 162 suspension clamp 189 swivel clamp 345 cathodic area 655 current 653 protection 653, 657 change in the conductor length 237 of gradient at supports 498 circuit condition 705 diagram 45, 311 group 36 connection 315 with reinforcing feeder conductor circuit breaker 46, 534, 555 monitoring 51 cis format 518 clamp 180 for electrical connectors 182 material 180 clearance gauge 77 re::;triction 297 to energised part::; 295 verification 330 clevis end fitting 185
555
climatic condition 83 effect 102 stress 219 clipping device 411 clothoidal point 278, 279 coefficient of self-inductance 520 of thermal expansion 236 of variation 565, 566 cohesive soil 377 collector head 89 running characteristic 74 strip 90, 267, 500 mass 511 material 504, 506 wear 74 combination factor 355 instrume,nt transformer 46 combined road/rail transport 77 come alongs 763 commissioning of the trackside facilities 669, 688 common mode rejection factor 4 71 commutation process 723 compact foundation 385 comparative tracking index 97 compensation current 545 joint 127 complete corrective maintenance 761 parts list 259 completely compensated overhead contact; line 118, 120 component 729 wear 466 compound contact line 122 equipment 201, 210 compression clamp 765 computer monitor 722 simulation model 453 supported configuration 33G
798
concentrated mass 445 reactive force 445 stray current corrosion 657 conclusion drawn from experimental measurements 600 concrete block 320 foundation 385 coverage 3 74 foundation 320 mixing train 733, 766 nominal strength 372 pole 319, 742 with solid core 352 strength 351 condition -related maintenance 755 check 756 conductance 534 per unit length 535, 659, 661 conductive soil 622 conductor grip clamp 765 length change due to elastic strain 236 negotiable in the raised state 288 non-negotiable in the raised state 288 rail 74, 109, 124, 219, 411, 588 disconnector 128 overhead contact line 420 ramp 128 separation 128 support 125 system 110 wear 128 sag 70 tensile force 341 cone-design dead-end clamp 184 connection fitting 180 material 180 status 713 connector disconnector 557 failure 745 consequential cost 776
Index
consistency of cohesive soils 381 constant availability 754 current distribution 645 construction and assembly work 731 construction approvals 335 consumed land 103 contact behaviour 439, 467, 502 characteristic 598 interruption 477 performance 4 75 quality 48~ 497,499 strip mass 486 contact force 466, 473, 474, 493 calculation 463 effect 499 graph 465, 495 measuring system 468 simulation 463, 497 transfer function 482 variation measurement 476 contact line 31, 109, 683 above loading or checking tracks 433 assessment 466 circuit 552 arrangement 517 design 553 diagnostic 755 dynamic behaviour 480 elasticity 467 equipment 234, 346, 348 supports 301 feeding section 548, 553 height 80 installation 731 damage 608 train 734 interruption 428 lateral registration 77 layout 731 plan 301 loop resistance 575 polarity 656 requirement 69 section insulator 75 service life 747
Index
standards in design and construction 94 system design data 337 model 456 to earth circuit 522 with offset support droppers 119 with semi-inclined suspension 121 contact wire 109, 110, 112, 745 clip 188 cross-sectional areas 492 crossing 283, 285 displacement 465 examination 757 exchange 775 geometry 284 gradient 75, 298 grip clamp 765 height 141, 287, 359, 756 mcrease 288, 427 reduction 326 initial position 467 lateral offset 70 position 140 lowering 297 material 504 melting 91 mirrored running surface 480 offset 241 under wind load 242 position 70 at still air 757 pre-sag 115, 142 replacement 762 splice 183 connector 746 stagger 140, 271, 301, 325, 483, 756 m curves 269 support 160, 167 surface structure 507 tensile strength 598 test-stand 505 thermal characteristic 607 thickness 480 through track 286 touching 282
799
uplift 139, 442, 453, 484, 486, 508, 511 vertical movement 484 wear 72, 297, 482, 745, 758 zero position 283 container terminal 432 contamination of insulators 86 continuous current 576 loading diagram 566 contrary flexure turnout 279 control and command system circuitry 691 installations 622 circuit breaker 57 location 264 of disconnector 57 system 57 convection speed 582 convenience power 87 conversion ratio 598 converter station 57 cooling time constant 5 78 copper -clad steel catenary wire 208 contact wire 113 -clad wire 114 -magnesium alloy 598 alloy 113 aluminium alloy 182 correction rate 754 corrective maintenance 759, 761 corros10n protection measure 71 protection of steel components 743 resistance 69 costs for maintenance 69 for operation 69 coupling factor 646 impedance per unit length 646 inductance 525 mechanism 704
800
post 36, 45 creepage current 748 crimping tool 765 criterion of 100 m V (536, 658 cross-connection of double-end feed contact line installations 554 cross-connector disconnector 557 cross-country suited vehicle 733 cross-coupling 546 cross-span 361 equipment 159 eye clamp 189 structure 733 support 352 tensioning spring 189 wire 347, 360 clamp 166, 188 spring 165, 360 crossbond 689 crossing -type contact line wiring 287 bar 281, 287, 293 between light-rail and trolley bus line 424 between mainline railway and trolley bus system 426 of different railway systems 409 crossover dropper 281, 288 current collector 434 device 110 distribution 517 drop 466 flowing to earth 654 impulse suppression chokes 574 inverter 66 lubricating effect 747 resistant dropper 195 through earth 636 type 70 current-carrying capacity 70, 74, 451, 576, 585--587, 589 curve in the track 22f> pull-off mo curved point 279
Index
d' Alambert's wave equation 458 d'Alembert's principle 445 damper 87 darn ping coefficient 467 element 212 clay's load coefficient 563 DC circuit breaker 66 dead load 219, 341, 353 weight 219 decentralised rotating converter station 35, 39 static converter station 35 defining pole locations 273 definition for operation 739 deflection 240, 350, 370, 375 speed 444 deformation 374 degree of elasticity uniformity 489 of freedom 454 of non-uniformity 143, 202 density 105 density function of the standardised normal distribution 566 depot 664 area 685 track clisconnector 409 depth of good bearing soil strata 382 design DB Rel00 202 DB Re200 202 DB Re330 202 ice load 344 load 364 of earthing installation 638 of overhead contact line system 86, 260 of the traction return 650 parameter 487 planning 257 short-comings 752 va.lue :~55 wind V(~locity 84, ;342
Index ----------------------destruction process 743 determining the mechanical dimension 219 dewired pantograph 110, 663 dewirement 240 diagnosis of equipment performances 615 diagonal feed circuit 554 strut 354 diffuse sky radiation 583 stray current corrosion 657 digital metering 55 value transfer 55 protection relay 615 diode rectifier 66 Dirac delta function 441, 443 direct touch voltage 624 traction earthing 626 traction system earthing 623, 663 direct current 32 railway 629 traction 36 discharge earthing resistance 687 disconnector 58, 75, 615, 616, 749 remote control system 311 dismantling 762 displaced overhead contact line 100 displacement at the pile head 395 disposal cost 775, 776 distance -time graph 73 protection 611 travelled 474 distribution line 69 of energy 61 of single-phase electricity 39 of the return current 675 disturbance 741 classification 759 transfer function 482 Doppler effect 449 factor 70, 139, 449, 452, 490, 508
double -decker passenger wagon 77 -slip crossover 277 bus bar 45 channel pole 350, 369 insulation 101 U-clamp 184 double-end feed 543, 553 with cross-coupling 553 downtime 753 drag coefficient 343 factor 231 drilled foundation 733 drilling machine 766 driven pile 733 foundation 320, 391 probe 380 steel pipe 649 tube 393 drizzle 231 drop bracket 188 feed 315 post 167 verticals 34 7 dropped pantograph section 741 dropper 112, 118, 140, 142, 155, 354 clip 183 height differences 498 layout 142 length 325 calculation 259 preparation 734 spacing 325 drum wagon 768 dual mode rail- and road vehicle 767 dynamic apparent mass 456, 482 contact force 93 range 477 correction 468 criteria 490, 492, 509 effects of stitch wires 497
801
Index
802
force 469 performance 493 range of the internal forces uplift 288, 491 component 489 uplift position 480 dynamic behaviour testing 757 dynamic interaction 69 dynamic quality criterium 70 dynamic uplift 288
4 77
earth 622, 638 bearing resistance 393 bus bar 685 conductor 661 current 642 electrode 623, 647 resistance 681 electrode resistance 712 megger 639 potential 624 pressure coefficient 394 rail 692, 693 resistance 643, 64 7 of the pole foundation 648 return current 645 rod 648 earthed upper cross-span wire 165 earthing all metal parts 725 bus bar 682 conductor 109, 110 device 740, 765 diagram 301, 309, 311 effect of the tunnel 683 installation 650 line 737 measure 663 plan 259 strip 647 switch 409 system 623, 682 maintenance 671 wire 110 effect of non-availability on train operations 755
effective current value 570 lcakance per unit length 650 length 714 effective leakance per unit length 650 elastic cantilever 117 converter 38 dropper element 122 support 117, 195, 307 elasticity 70, 119, 120, 138, 139, 451, 487, 492 at the middle of a span 487 calculation 457 of the overhead contact line system 495 uniformity 489 electric conductivity 598 contact resistance 90 isolating joint 693 potential 622 rise 712 section 552 shock 71, 97, 634, 677, 718 protection 622, 635, 667 traction system 703 wear component 505 electric field 94, 104, 635, 680, 718, 724 effects on human beings 719 strength permissible value 718 electrical accident 97 arc 466 bonding of conductive metal reinforcement 666 characteristics 517 circuit diagram 658 connection 155, 180, 307, 422, 688 disturbance 517 energy 31 erosion 744 load 94 on traction systems 31 power 32 rating of the contact line 138
Index
requirement 70 resistance to power transmission 518 sectioning 267 plan 264 separation 72, 76, 300 stress 219 train operation 738 electro-chemical corrosion 653 equivalent 654 series 742 electrode resistance 688 electrolytic copper 114, 597 tough-pitch 598 electromagnetic field 673, 724 electromagnetical disturbance 517 electromechanical tensioning device 154 electronic analogue protection equipment 610 information processing 45 electrosmog 718 embedding depth 394 emissivity 581, 588 of a black body 581 empirical failure rate 752 energised pantograph 100 upper cross-span wire 205 energy exchange 61 generation 43 regeneration 540 supply system 74, 157 transmission behaviour 51 7 engineering structure 296 environmental aspect 102 disturbance 466 impact study 103 protection 69 equation of motion of taut strings 459 of state change 237 equilibrium of forces at tlit~ nodes 460 equipment identifier 306 equipotential bonding measure (i:30
803
equivalent circuit diagram 539 flux density 722 radius 538 span length 238 track resistance 643 working load 372 erection 729 principles 729 ergodic hypothesis 566 Erlang-k distribution 753 European standards on foundations 403 evaluate the actual status 750 evaluation of measurement 479 of quality variation 466 even-order higher harmonics 707 examination of the de-energised overhead contact line 757 excavator 766 exceptional load 350 excitation vector 461 existing line 265 expansion gap 128 joint 72 expected absolute service life 746 explanatory report 258, 335, 336 explosive pile driver 766 exposed terrain 86 extent of soil investigations 384 external impact 752 inductance 523 extreme ice load 86 value 476 eye clip 186 facing pole location 306 failure causes for contact lines rate 751, 755 Faraday's first law 654
752
fast high-cmrent protection
GHi
fatigue phenomena fault
744
I
I
804
_____________________________________________ Index
analysis 608, 615 removal 741 repair 761 report 759 feeder clamp 184 disconnector 557 line 109 section with different phases 157 feeding section 36, 71, 539 transformer 662 ferromagnetic material 520 finite element analysis 245 method 457 modelling 455 fishplate joint 689 fitting-free area 281-283 five-span overlap 148 fixed termination 154 flash over 747 flat wire profile 112 flexible cross-span 345 cross-supporting structure 357 head-span 160,352 steel conductor 114 support equipment 34 7 flood gate door 411 folding bridge 416, 417 force coupling between contact wire and catenary wire 245 exerted on the contact wire 453 in upper cross-span wire 360 measurement method 467 forced convection 580, 586 forecast calculation 466 foundation 109, 376 removal 763 table 259 type 385 four-point method 639 Fourier series 441 free convection 580
French State Railway 201, 210 frequency response analysis 482 frequency-analogous digital signal 471 frequency-dependent finite element 457, 458 matrix 458 frequency-effective power control 707 friction-induced force 229 functional group structure 190 module 191 specification 260 test 756 fundamental waveform 707 fusing current 592 future planning 264 galvanic coupling 621, 640, 641, 645, 704, 711, 724 interference 635, 725 galvanized steel conductor 114 wire 114 Gaussian distribution 4 76 standard error function 566 gear wheel 151 general control system 59 power system control 60 protection 51, 64 traffic railway line 594 geotechnical efficiency 393 reliability 395 glass cap-and-pin insulator 748 glass fibre reinforced plastic cantilever 188, 749 gliding dropper 141 shoe 425 Global Positioning System 265 global radiation 583 grade level crossing 295 graduated rule 77 4 graphite contact strip 7 16 1
Index
Grashof number 579 greatest lateral offoet 240 grooved contact wire 112, 604 groundwater clanger to concrete 381 table 391 guarantee human safety 652 guard to prevent accidential access
--·--~--~ ~-·--805 -----
helicopter 733, 766 high quality overhead contact line high-current circuit breaking 610 prot.edion
173
H-beam pile 733 pole 370 steel pole 350 H-beam steel pole 210 half tensioning section length 111 hard porcelain 176 hard-drawn electrolytic copper 113 harmonic frequency 71 harmonics generation 707 hazard of ground water to concrete 381 to persons 608, 703 head span wire 347 head-span 164, 188, 307, 357, 733 length 307 pole 348 structure 320, 766 wire 165, 320, 360 clamp 166, 188 dropper 165 support 166 headroom restriction 296 heat energy 540 proofness 608 transmission radiation component 580 transmission coefficient 578, 579 heating time constant 578 heavy-duty railway line 569 height -adjustable dropper 155 for passing oversize transport 428 limiting structure 427 of contact wire 70 of fixing 3G3
755
610
high-duty overhead contact line 747 high-grade stainless steel wire 114 high-performance pantograph 87 high-pressure press 765 high-speed overhead contact line 70, 111, 120, 736 railway line 551, 569, 595 Madrid-Seville 198, 208 Tokaido 210 train traffic 493 high-voltage circuit breaker 63 higher harmonics 705, 706 model for calculating 708 propagation 707 higher-frequency electromagnetic interference field 705 highest temperature 83 track-to-earth voltage 632 hinged cantilever 160, 162 tubular cantilever 185 hoarfrost 231 hollow aluminium extruded rail 125 hook clip 186 hook end fitting 186 horizontal catenary contact line 123 component of the head-span wire 358 conductor tensile force 341 force 475 force acting 224 registration 34 7 registration arrangement 361 stitch wire 124 horizontally swivelling contact line 432 hot-clip galvanisation 743 hot-dip galvanised steel cantilever 744 hour's load coefficient 565
Index
806
hydraulic tensioner
152
ice accretion 341, 342 effect 353 load 71, 231, 344 impedance 517, 518 angle 528 measurement 526 per unit length 522, 530, 645, 675 protection 610, 611 reactive component 518 imperfection coefficient 356 implementation 688 of changes 336 impulse voltage withstand level 95, 97 inclined catenary overhead contact line 121 indirect contact 99, 652 electrical contact 626 touch voltage 624 individual pole 135 repair 761 individually sprung collector strip 455 indoor equipment 48 switch gear 63 induced voltage 94, 688 inductance 518 per unit length 524 inductive coupling 587, 621, 645, 712 interference 635, 680, 686, 712, 725 inductively coupled conductor loops 711 influence 717 range 703 voltage 718 information-technology equipment 722 initial sag 496 short circuit, alternating current- 591 inner self-inductance 523 inpermissible touch voltage 680 input amplifier 4 71 inserted pole 320
insertion length 315 inspection 750, 759 installation wagon 773 instructed person 738 instrument transformer 610 insulated gliding runner 425 overlap 146, 148, 156, 556, 557 rail joint 309, 664 steady arm 186 track joint 692 insulating material 176 overlap 300 pad 641 rod 177 insulation co-ordination 71, 86, 94, 95 insulator 175 eye cap 186 integrated contact line stringing 735 installation unit 735 network 57 overhead line installation 734 interaction assessment 466 of a pantograph with an overhead contact line 511 of the contact line with pantographs 509 pantograph with contact line 89 interference 635, 680, 694 to cathode-ray tube monitors 722 parameter 704 voltage 696 inter locking 55 intermediate pole 348 intermediate track stage 265 internal force 4 73 measurement 468 internal friction angle 382, 396 International Union of Railways 77 intc!roperability 77 of the trans-European high-speed rail system 78 intt\rsecting point wiring 281 invc~11tory or revised plan 265
807
Index
investigation boring 379 investment 69, 139 irregularity 741 isolating transformer 51 Italian State Railway 200 Japanese Railway Joule's heat 577 loss 586
210
keraunic level 86 kinematic displacement 250 of the centre of teh pantograph head 250 Kirchhoff's law 654 Lotschberg-Bahn 208 Lagrange's equations 457 latch-in device 151 lateral contact wire forces examination 289 contact wire position 475 deflection 225 displacement 84, 247 earth resistance 385 force 225 movement of the vehicle 248 offset 225, 240 position 286 position of the contact wire 287 voltage drop per unit length 540 lattice steel pole 344, 350, 363, 366 layout plan 259 lead-antimon alloy 749 leakage current resistance 176 leakance per unit length 641, 645 leg member force 367 level crossing 423, 426 clearance increase 429 life cycle cost 775 lifting bridge 420 drive 87 lightning 687 arrester 668, 685 discharge 86
intensity 86 . protection 687 conductor 109 rod 47 strike 668 stroke 86 voltage surge 86 lightweight steady arm 289 limit strength of a foundation 385 limiting speed 450 line branch 555 current load 550 feed plan 553 feeder 110 diagram 267 gradient 77 impedance 518 per unit length 525, 527, 540 post insulator 171, 175, 177, 205 potential 655 running 483 list of co-ordinates 264 load 219 current 549 due to erection 345 due to maintenance 345 from crossbeams 348 interrupter 173 per unit length 219 probability of occurrence 566 loading assumptions 349 combinations 349 due to erection 372 due to transport 372 facility 409 histogram 566 siding disconnector 55 7 track 433 local control 53 unit 58 track layout 301 local-area railway system 76
;e.:80=8:......___ _ _ _ _ _ _ _ _ _ _ _ _ _ -------··-·--··
traffic 72, 74, 77 localized irregularity 439 localized temperature distribution 604 location of sustained short-circuit; G15 long-distance railway network 75 traffic 72, 7G long-lived component 7G2 long-rod insulator 176, 748 long-term availability 754 longitudinal bond 689 contact line equipment 112, 219 disconnector 50, 557 displacement 285 earth strip 684 line gradient 325 profi~ 259,325,326 of the currents 644 protective fixing 127 rail voltage 625, 635, 666 resistance 670 per unit length 641 span length 110,247,252 voltage 674, 714 drop 539,636,666 gradient 666 per unit length 712 loop conductor 685 insulator 177 loss by radiation 586 of contact 723 of functionality 751 low maintenance aluminium cantilever 202 cantilever 206 low silver tough-pitch 598 low- pass characteristic 707 low-voltage protection earth 673 low-voltage transformer 50 lower cross-span wire 165, 320 lowest ambient temperature 83 Metro Leger de Tunis 192 magnesium-copper-alloy contact wire
608
Index
magnetic induction 718 permeability 519 space constant 520 magnetic field 94, 104, 635, 675, 680, 718 effects on human beings 719 strength 718 permissible value 718 main circuit group 58 equipotential bus bar 682 frame 87 line railway 563 maintenance 750 -friendly component 755 cost 775 free long life 352 installation 409 intensity 754 methods 750 of electric traction vehicles 409 overview 758 test run 479 malleable cast iron 182 component 182 management 729 manufacturing investment 775 mass inertial force 468 per unit length 219 Mass Transit Railway 195 master card 758 control centre 54, 57, 59, 60, 616 protection 609 switch 409 material procurement 325 data 759 disposal and separation 763 list 335, 336 selection 336 maximum clearance 426 contact wire height 70, 427
809
Index ---sag 235 deflection 356 due to wind 241 expected load current 5\n lateral offset 243 mean load 570 operating speed 442 permissible contact wire uplift 433 permissible touch voltage 628 principle 593 rail potential 670, 678 span length 247 tensile force 219 vehicle height 428 voltage drop 541 calculation 548 working temperature 583 mean annual power consumption 566 contact force 477, 499, 502, 509, 510 power factor 550 time between failure 753 time to repair 753 useable voltage 539 wave propagation speed 451 measured impedance of single-phase AC railway line 532 measurement 638 technique 466 measuring car 469, 471, 737, 774 pantograph 774 system for contact forces 468 mechanical connection 180 design 94, 487 impedance 482 load 94 rating of the contact line 138 requirement 70 separation 76, 164 stress 219 wear component 505 medium-voltage protection earth 673 melting temperature 59(; metal collector strip 90, 506
eros10n 654 metropolitan 689 railway 74 mid-point 111, 167 anchor 119. 184 pole 312 anchor pole 226 pole 348 mid-point anchor 149, 150 minimum air gap 70, 97 clearance 326-328, 331 at level crossing 427 verification 332 contact wire height 70. 75 creepage distance 97 cross sections of earthing conductors 669 electrical clearances 756 short-circuit current 575 tensile strength 105, 596 mixed granulated soil 377 modal mass 461 modal node reaction 461 module 518 modulus of elasticity 105 momentum-loaded block foundation 388 monitoring 109 monthly mean load 563 movable bridge 415 mud 377 multi-phase cable 704 multi-system traction unit 414 multi-track cantilever 160, 164, 307, 346 multiple -phase system 626 electromagnetic coupling 519 pantographs 502, 510 system traction unit 412 traction unit 503 mutual impedance oer Huit length 525 inductance 523, 525 per unit len[!,tlt 523, 71(, natural
810
frequency 451,458,460,462,467 vector 458 nature protection 69, 103 negative feeder 42, 626, 672 network command centre 57, 61 impedance 709 power system control 57 neutral earth 622 section 36, 157, 158 new line 263 node-type substation 44, 56 nominal contact wire height 287 tensile strength 596 voltage 70 tolerance 539 nominated person 738 non-cohesive subsoil 377 non-insulated overlap 272 non-routine maintenance depending on inspection results 750 normal distribution 565, 753 normal loading 372 normalised wear rate 505 Norwegian Jernbaneverket 205 Nusselt number 579, 586 object-class hierarchy 339 October Railway Moscow-St. Petersburg 199 ohmic coupling 519 voltage drop 637 one-handed operation 53 open traction earthing 626, 660, 663 open traction system earth 624 open traction system earthing 678 open-air depot 65 open-air switching equipment 63 open-circuit potential 668 operating and operator cost 775 bus bar 48, 49 condition 72 current 94, 705
Index
pattern 705 data 759 overcurrent 75 range of the pantograph 247 of the tensioning mechanism 146 signal standardised 55 speed 139 standard 739 tensile stress 254 operation at near-maximum speed 493 of the electrical equipment 729 of the network 61 of unmanned installation 57 operational current 576 operational life cycle cost 137 optical contact wire position measuring system 479 optical plumb 774 optimum efficiency 552 ordinary person 738 organic soil 377 outage method 750 outdoor temperature 83 over section insulator 749 over-current relay tripping 75 time protection 610, 614 time sensing circuit 613 overall earthing system 680 impedance per unit length 525 inductance 525 speed 74 strategy for earthing and bonding 671 voltage drop 540 overhead circuit diagram 266 overhead conductor rail 129, 415, 416 system 80 overhead contact line 51, 64, 74, 110, 111, 259 -rail voltage 94 area 652, 663 circuit 555
Index
collector interaction 114 components 741 diagram 335, 336 disconnector 173 discontinuities in the position 480 disturbance 761 elasticity 486 equipment 135, 183 inspection motor coach 770 installation 190 vehicle 772 wagon 767, 768 layout 311 lifting installation 429 maintenance vehicle 771 network 57 operation 739 position 4 79 protection 51, 53 reconstruction train 773 removal 763 service life 775 spectrum 451 standard design 110 switching diagram 267 swivelling 432 symbols 301 system 109, 111, 219, 257, 265 conversion 265 height reduction 259 layout 257 layout plan 300 planning 257 table 259 thermal stress 570 type 110, 137, 247 uplift 467, 503 with catenary suspension 118 zone 100, 110, 625 overhead contact rail system 142 overhead traction power line protection 51 overlap 148, 272 section 137, :MS overlapping block 137
811
section 276, 285 span 276 oversize transport 426 overvoltage protection 87 protection circuit 687 protection device 95 pantograph / contact line interaction 91 area 663 assessment 466 characteristics 499 contact line interaction 439 defect 485 design 496, 499 dewirement 747 diagnostic 485 dynamic characteristics 482 for high speeds 499 head working range 248 head working range 248 main characteristic data 89 maximum development 427 mechanism 453 motion 463 oscillation modes 455 passage 757 requirements 509 running performance 483 test stand 468, 473 trap 283 vertical motion 467 zone 100, 110, 625, 683 pantograph-type collector 115 parabola equation 233 parallel feeder 307, 349 line 109, 110, 139 feeder line 195 groove clamp 184 reinforcing return line 657 return conductor 667, 674 return current conductor 667 span 137
812
parent substation 60 partial factor 350, 355. 399 partial or complete dismantling 432 partial renewal 762 passive earth pressure 396 passive protection 657 pendant-type suspension 116 penetration depth 524, 643 penetrometer 379 performance limits of the wheel-on-rail system 507 permanent action 355, 364 electrical connection 155 elongation 596, 602 load 372 short-circuit 613 supervision of safety of people 638 way 312 permissible accessible voltage 629 contact wire gradient 70 final temperature 578 operating current for a pantograph 90 soil pressure 382 tensile force 221 tolerances 736 touch voltage 628, 662, 679 voltage values 635 personal safety 341, 677, 687 phase angle 518 constant 646 separation section 62 separation section with a neutral zone 158 photogrammetric recording 265 physical property 104 piggyback load 77 transportation 77 pioneer pole 768 planning 257 document 260, 336 plastic cantilever 182, 195
Index
insulator 176, 748, 749 section modulus 355 platform combustion motor coach 770 point. 277 centre 277 designation 279 end 277 layout diagram 285 start 277 wiring 278 point of resonance 708. 710 analysis 708 assessment system 710 pole 348 damage 742 erection 731 family 368 gap 76 geometry 315 length 314, 315, 359, 363 location 296 position 353 selection 312 setting 766 table 259 type selection 319 polling 59 polygon calculation 259 porcelain cap-and-pin insulator 748 insulator 748 portal 160, 167, 306, 307, 323 bridge length 325 structure 135, 201. 347 position of intersecting contact wires 756 potential compensation 682 control 673 difference 5,54, 695 drop 528 of the tunnel structure 670 on running rails 652 potentially susceptible system 704 power control concept 706 electronic circuit 706 factor 568
Index __________________ -----~------==:.__ for propelling the train 518 loss 74, 528, 540 duration 467 network control centre 55 voltage 704 plant 57 requirement 563 supply for DC railways 651 system asymmetry 703 system control 55, 57 system control 60 transformer station 35 use 61 power-electronic converter 681 Prandtl number 579 pre-sag 142, 496 pre-stressed glass 176 pole 351 preliminary design study 257 preparation of diagram 336 preserve the planned status 750 preventive maintenance 755 primary protection 609 probability factor 714 of lightning currents 86 probe boring 379 processing of the wiring 336 production 730 profile clearance 286 profile gate 173, 295, 427 project -specific global data 337 -specific structure 259 documentation 335 implementation planning 257, 258 schedule 264 propagation constant 642, 646, 654 protection against electric shock 98 against stray currents 651 by screening 98 for the reinforcement 742
_ _ _ _ _ __..::813
relay setting 610 tripping 678 protective clearance 98 earthing 301, 308 equipment 109 helmet 765 measure 71 neutral section disconnector 557 obstacle 98 provision 608, 676 against electric shock 652 against stray currents 657 section 413 public grid 62 pull-off 169, 306 force 227 support 120, 160, 497 pull-over concrete pole 315 pulley -sheave 116 -wheel tensioner 200, 201 block 151 principle 152 system 733 pump storage plant 43 push-off support 120, 160, 497 quality assurance system 730 of energy transmission 466 quenching chamber 66 radial contact line registration 348 force 272 load 227 in curves 325 of the catenary wire 353 of the contact wire 353 radiation heat transmission coefficient 581 radio frequency interference 722 rail -earth potential 94 -fracture detection 311 -to-earth impedance 640
SL!
-to-earth potential 626 -to-earth resistance 640 measurement 640 -to-rail resistance 641 bond 689 joint bond 660 potential 623, 624, 637, 642, 645, 646, 664, 674, 678, 679, 683, 688, 695, 696 measurement 671 railway -owned earthing system 661 bridge 299 crane 766 crossing 264 earthing 309 for general traffic 549, 563 on viaducts 688 system instructed person 738 purpose 72 traction supply system 158 raised working platform maintenance vehicle 771 raising the contact wire by means of erection devices 431 rated voltage 568 rating based on Eurocode 355 of cross sections 366 of foundation 366 of poles 363 of the support wires 362 reactance bond 692 coil joint 689, 692 coil joint transformer 692 reaction force 472 reaction moment 393 reactive component 519 receiver object 449 recrystallization 598 rectangular tunnel 169 rectifier equipment 574 substation 37, 65, 75 reduced system height 155
Index
reducing of repair times 755 reduction coefficient 713, 714 reference earth 622 reference wind velocity 342 refler.ted wave 446, 447 refledion coefficient 446, 448, 450, 490, 509 factor 70, 450 of transversal waves 449 regenerative object 751 regional wind velocity 139 registration arm 354 dropper 186 reinforcement 693 relative permeability 519 relay implementation 55 reliability 736, 750 model 754 of electric railway operation 69 remaining service life 753 remote control module 58, 59 node 60 system 59 technology 57 unit 60 control system 55 diagnosis 57 earth 622 remotely controlled disconnector 739 repair 750 representative overvoltage 95 resetting force 228 residual contact wire dimension 468 residual-current circuit breaker 662 resilient overhead contact line 109 resin encapsulated current transformer 50 resistance component 519 of earth return path 520 per unit length 519, 530, 540, 646 to aggressive substances 69 to corrosion 69 to earth 623, 670 to earth of tunnel systems 662
Index
815
to ice 69 to wind 69 resistive interference 680 resistivity 519 resonance characteristic 442 resonant-earthed condition 47 restore the planned status 750 return circuit 110, 625, 626, 635, 651, 680 interruption 635 return conductor 625, 672, 684, 693, 694 installation 675 system 672 return current 672 cable 110 circuit 308 conductor 109, 110, 208, 621 connection 309 contact blades 422 rail 110 through track and earth 674 return feeder 677 Reynolds number 579 rigid conductor 125 converter 38 portal 345 rippling and kinks 745 road bridge 686 road vehicles with working platforms 767 rock 376, 378 classification 381 foundation 381 roughness parameter 342 round foundation 320 route mean square 4 76 route-related constraint 294 routine maintenance 750 running performance 477 rail 110 potential 662 speed 76, 474 safe traction current return safety belt 765 clearance 70
309
connection 433 measures 660 of person 664 of persons 635 verification 638 provision 650 sag 326, 358 of a conductor 232 of conductor 70 of head-span wires 357 satellite control centre 60 scope of the project 264 section disconnector 552, 557, 558 insulator 156, 158, 300, 552, 557, 765 installation 736 pole 348 testing 613 secure in operation 69 security 635 selection of the erection technology 731 selectivity configuration 552 principle 613 self-impedance per unit length 525, 646 self-inductance 523, 524 of conductor-earth circuit 523 per unit length 523, 525 self-propelled multi-purpose vehicle 770 semi-compensated overhead contact line 118, 119 semi-horizontal contact line equipment 121 separation between electrification systems 412 separator for rolling doors 409 seperate earth 622 service frequency 563 service life 69, 506, 736 of concrete pole 74:3 of contact wires 504 of porcelain iusulators 749 of the contact wire 745 serviceability 356 servicing 750 shear force 470 Shinkansen 210
816
shoe sole resistance 628 short circuiting 622 short neutral section 158 short-circuit 141, 571 capability 590 current 75, 94, 571, 576, 634, 705, 712 capacity 70 cumulative frequency distribution 574 duration 591 rise 575 current-carrying capacity 590, 591 duration 634 frequency 575 initial symmetrical AC power 572 localisation equipment 616 position 757 rating 590 sensing relay 615 state 71 tracing system 615 short-circuit current initial symmetrical 572 peak 572 sustained 572 symmetrical breaking 572 thermally equivalent 572 short-circuiter 65 short-circuiting device 626, 664, 667 short-term current-carrying capacity 589 short-term thermal effect 605 side-contact conductor rail 125 signal 295 and measured value processing 55 for electric traction 311 position layout 264 visibility 295 signalisation 172 signalling 422 device 686 installation 664 silicone material 749 simple catenary-supported overhead contact line design 118 simple contact line design 11 7 simulated test runs on lines 48;~
Index
simulation of contact forces 497 of elasticity 497 of two pantographs 465 single -arm pantograph 501 bus bar 45 cantilever 306 pole 306 track cantilever 160 single-end feeding 541, 553, 572 single-phase AC railway line 643 AC supply 33 earth connection 576 generator 37 oil transformer 46 single-point suspension 115 single-rail insulation 689 site-related failure rate 752 skew pendant 116 skilled person 738 slacking of the dropper 448 sleet 231 sliding -type disconnector 50 contact 69, 504 current collector 109 dropper 297 mount 116 sling 765 slip switch 277 smallest radius 77 soffit conductor rail 109, 111, 129, 132 post 169 soil characteristic 382 condition 263 conductivity 639 fill 376, 378 investigation 378 pressure 385 re;sistivity 524, 623, 639 type 320 solar absorption coefficient 577
Index
-----~------
radiation 583, 586 radiation intern,ity 577 solution in the frequency area 457 source of disturbance 704 of harmonics 706 spade end fitting 186 span 110 span length 139,140,273,276,306,494 Spanish State Railway 208 spark discharge 723 special equipment 763 installation vehicle 767 vehicles 763 specific electric conductivity 105 electric resistance 105, 519 energy demand 705 heat 105 resistance 519 speed 563 of wave propagation 70 spinning process 374 spring constant 239 elasticity coefficient 460 spun concrete pole 350, 393 stability of the overhead contact line system 84 Stadtwerke Oberhausen AG 194 staff training 738 stagger 70, 240, 267, 342 staggered pole location 306 stainless steel 208 contact surface 127 standard overhead contact line design 494 penetration test :381 substation 44 switching substation 61G standard deviation 476, 477, 565 for electrolytic copper 602 standard deviation of dynamic forces 499 standardisation of contact li1ws 94 sfall(lardised
building 56 equivak11t. continuous load cmve 571 loading diagram 56G standing surface 98 static force 469 clearance 296 contact force 91, 510 quality criterium 70 station branch 555 fmb-section 556 statistical analysis 759 recording 759 steady arm 160, 188, 354 attachment 744 steady-state short-circuit 576 steel cantilever 182 catenary wire 745 conductor rail 125-127 pole 733 reinforced concrete pole 372 tunnel 683 step voltage value 628 stitch wire 112, 117, 119. 138, 1-13. 184, 202, 496, 497 stitched catenary 453 supported 110 contact line 120 stope-type contact line 434 straight stretch 228 strain gauge sens01 470 stranded conductor 114, 220 stratification density 380 stratification of non-colwsi ve soi ls :rn l stray current 65, 625. G50, 7m, 70-1 calculation 659 collecting 672 net G59, (i(i() ('OlTOSIOn ;37. 71. G2 L G2G. (j;_l(j G5:l, GG7, G7 I, 72G_ 712 area 652
drai11ag
(i59. G7 I
Index
diode 659 protection 662, 669 measures 660 strength 70 strip-type earth electrode 673 structural analysis 483 connection 180 structure earth 623, 652, 661 earthing system 663 sub-section 555 of open stretches 555 of stations 555 subgrade 640 subsoil condition 264, 376 investigation 376 substation 44, 57, 682 capacity 552 control centre 53 control protection system 64 earthing system 64 7 section link disconnector 557 supply section 36, 553, 555 substitute feeder branch 555 substitute mass 454, 460 substituted network impedance frequency-dependence 710 suitability for pile driving 382 sunlight 71 super-elevation 76 supercooled rain 231 superstructure 640 asymmetric 641 symmetrical 641 supervisory control and data aquisition 53, 59
supply feeder 349 support 110, 348 height differences 498 type 353 supporting structure 109 surface t,arth electrode 64 7
surge arrester 171 impedance 642, 646, 713 surveyor's layout plan 263 survival probability 751 suspension insulator 171 set 349 po~ 312,348,349 sustained short-circuit 741 swinging strap 189 switch symbol 172 switch-gear 109 switchable overhead contact line 414 switched connection 155 switching and control transient 723 command controller 739 dialogue 740 group 266,553,556 instruction 740 operation 311, 739 post 35, 45 section 36, 276, 553 boundary 267,276 service manager 739 substation 44, 555 switchover 281 swivel 185 cantilever 345, 346 swivelling bridge 418 symmetrical oscillation 451 synchronous-synchronous converter 38 synthetic rope 115 system capability characteristic 593 configuration 651 constraint 263 height 80, 140, 325, 326, 359 separation section 412 in st.atious 433 system height 495 system separation st.a.tiou 414 f.augent.ial switch wiring
281
Index
wiring of points 292 tank leakage protection transformer 46 technical acceptance 737 explanation 336 requirement 260, 336 telecommunications and signalling 673 telecommunications device 686 telegraph equation 713 telescopic pole 774 temperature changes 749 coefficient 519 of resistance 105, 579 drift 471 increase of the contact surface 606 temporary dropper 734 tensile force 221 tensile strength loss 599 standard distribution 602 tension length 253 tensioning equipment 119, 135 length 495 mechanism 151, 225 pole 348 section 348 length 110, 143, 149, 247, 274 spring 154 system 118 weight 151 termination pole 312 terrain formation 86 terrestrial survey 265 test bus bar 48, 49, 613 operation 729 standard 730 thermal conduction 604 conduction capacity 105 conductivity 90 energy balance 5 77 expansion 127, 285 coefficient 105 load capacity 571
819
loading capability 576 overload protection 610, 613 protection device 614 rating design method 593 of contact lines 595 resistability 576 stability 506 thennovision 758 device 77--1 thimble 183 thin walled steel pole 350 third party earthing inst.a.llation 669 system 668 third rail 64. 109 third-party earthing installation 686 three-phase AC feeding network 651 power supply (ifi2 three-span overlap 118 threshold voltage 626 through-track 277 thyristor-controlled traction vehicle 710 time constant 584 graph of the load current 570 synchronisation 59 window 570 time-weighted equivalent continuous load curve 570 parameter 595 tolerance limit 498 top anchor 162 topography 263,265 torsional stiffness 370 total current monitoring 51 total reaction force 386 touch circuit 628. 62!l voltage 62--1, 635, 637, 638, 652, 685. 688, 695 protection 678 track -earth pote1ttial 101 -to-earth conductance 5:3--1
820
-to-earth leakance 517 -to-earth potential 635 -to-earth voltage 71, 534, 634, 642, 645,646,656,667,673,674 bond 689 circuit 691 operation 691 design 72 insulation layout 264 layout 263, 265 plan 300 point 277 designation 279 radius 325 radius-dependent position limit 251 release circuit 309, 681 release installation 664 release system 641 return circuit 637 return system 110 spacing 76 superelevation 325 superstructure 650 to be wired 264 to earth circuit 522 to-earth voltage 630, 631 with both rails insulated 691 with concrete sleepers 640 with one rail insulated 691 traction current 621, 682 of tractive units 548 return path 691 earth 626 earth bond 693 earthing 622 earthing system 712 design 694 energy generation 34 substation 662 system earth 678 system earth 623 vehide impedance 548 (;raction power 57 central supply 38
collection 31 decentralised supply :rn distribution 31 feeding 31 generation 31 line 326, 328, 348 rectifier station 35 substation 31 supply 31 supply line 264, 737 supply system 651 transmission 31 traction-force/speed characteristic 73 traffic volume capacity 72 train -in-section effect 676, 677 frequency 73 weight 563 with tilting bodies 76 tramway 74 line load 565 operation regulation 82 transfer function of disturbances 482 transformer 64, 706 protection 51, 52 relay 53 transient earth fault relay 52 transient load 219 transition length 527, 645, 646 range 527, 704 resistance 744 section 645 transmission control centre 57, 61 of electrical energy 39 transversal impulse propagation :l3!) transverse profile 259, 26°1 diagram 312, 335 travel of the cantilever 28!) triple tangential wiring of poiuts 292 trolley bus contact liuc 346 trolley bus overhead contact line l l 2 trolley wire contact li1w 192 trolley-type contact. li1w 74. 115 with stitch susp<)ttsiou 117
/l ( I I
\
Index
overhead contact line 111, 434 trolly bus line 74 tube-type swivel ca1ttilcwr 353 tunnel cross section 141 earth 623 earthing system (i5 overhead cont:u:I. line equipment, 14 l support :307 turntable equipuw11t -llO twelve-pulse direct. ctlrt(~nt. GG twin contact wire 1 l2 two-handed operntio11 53 two-stage distance protect.ion 610 unbalance or asymmetry 724 unbalanced ice accretion :350 under-impedance trigg(\riug 611 undisturbed soil :376 uniform electric load distrilmtion 654 uniformity 70 uniformly-distrilrnted line load 541 uninsulated track 691 unintentional cnergiziug of the earthed secti011 413 unistrut 169, 683 unit weight 382 uplift measmiug d(ivini 48°[ upper cross-span win' 1G5. :J20 urban railway 71, 7G vacuum circuit IH('ab·1 45, 49, 63 value mo11it01ing 55 valve-type ancst.or 87 variable action ;\(j.l variable load 342 variation iu the hmi,,ontal tensile force 2S4 vehicle gaug(i envelope ;H)(j passage 29;> sway 471) verification 1ll(!itS\lrt~n1c11t (i(j\) of ca1thi1tg provisions G88 vertirnl
acceleration 475 catenary suspension 74 component of support forces 358 load 341 due to the contact line 353 due to the ice-covered contact line 35:3 pant.ogrnph lllotiou 474 po:-;itionof the pantograph t.op 475 viaduct 685 vibration pile driver 7GG visual inspection 688 voltage condition 546 drop 74. 466, 538, 541, 543, 545, 660 algorithm for calculation 546 fuse 678 fuses 652 limiter 101, G26, 692 1 743 limiting clPvicc 623, 652, GG0 limiting fuse GG3 loss 467 monitoring device GG4 of the contact line net.work 70 stability 517 transforn1er 50 unballaun' 40 washing and (fo-icing plant. 410 waste dump 7G:J water to cenwnt. rnt.io J74, 742 wave equation °140 model ,Ol propagation sp(•(id l:18, 440, 442, 447, 45L -lG2, -l!J0, 508 wear 492. 7-11 measur<'lll('ltl SOS rate 5(l:"i wcdgc-typ(' d(';1d-<'11d cla111p l 84, 185 weighting fuuct io11 l(i l \Venner uwt hod G:rn wet suow 2:31 \\·heel t.ensiot1(•t 21 (l wheeled ladd('l 1(i:1 wiud action l l l . :\:i:l
822
Index
assumption · 85 deflection of an overhead contact line equipment 244 displacement 271, 287 load 219, 229, 342, 343, 353 per unit length 231 region 85 speed 247 stay 161 ,. velocity 71 wiring 257 of points 277 withstand voltage 95 work in the electro-technical system 729 working inductance 522, 524 working range of the collector head 89 of the panto'graph 90 of the tensioning equipment 254 workshop area 664, 685 world co-ordinate system WGS 84 266 world record speed 210 for railway vehicles 508 wrought copper alloy 114 yield strength
355, 596
zig-zag 267 arrangement
112
