CECW-EP
Department of the Army
EM 1110-2-3006
U.S. Army Corps of Engineers Engineer Manual 1110-2-3006
Washington, DC 20314-1000
Engineering and Design HYDROELECTRIC POWER PLANTS ELECTRICAL DESIGN Distribution Distribution Restriction Statement
Approved for public release; distribution is unlimited.
30 June 1994
EM 1110-2-3006 30 June 1994
US Army Corps of Engineers ENGINEERING AND DESIGN
Hydroelectric Power Plants Electrical Design
ENGINEER MANUAL
CECW-EP
DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers Washingt Washington, on, DC 20314-10 20314-1000 00
Manual No. 1110-2-3006
EM 1110-2-3006 1110-2-3006
30 June 1994
Engineering and Design HYDROELECTRIC POWER PLANTS ELECTRICAL DESIGN
1. Purpos Purpose. e. This manual provides guidance and assistance to design engineers in the development of
electrical designs for new hydroelectric power plants. 2. Applicability. Applicability. This manual is applicable applicable to all civil works activities activities having responsibil responsibilities ities for the
design of hydroelectric power plants.
FOR THE COMMANDER:
WILLIAM D. BROWN Colonel, Corps of Engineers Chief of Staff
DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers Washington, Washington, DC 20314-1000 20314-1000
CECW-EP Manual No. 1110-2-3006
EM 1110-2-3006 1110-2-3006
30 June 1994
Engineering and Design HYDROELECTRIC POWER PLANTS ELECTRICAL DESIGN Table of Contents Subject
Paragraph
Chapter 1 Introduction Purpose . . . . . . . . . . . . . . . . . . . . . Applicability . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . Scope . . . . . . . . . . . . . . . . . . . . . . . Codes . . . . . . . . . . . . . . . . . . . . . . . Criteria . . . . . . . . . . . . . . . . . . . . . . Hydroelectric Design Center . . . . . . . Chapter 2 Basic Switching Switching Provisions Provisions One-Line Diagrams . . . . . . . . . . . . . Plant Scope . . . . . . . . . . . . . . . . . . . Unit Switching Arrangements . . . . . . Substation Arrangements . . . . . . . . . Faul Faultt Curr Curren entt Calc Calcul ulaation tionss . . . . . . . . . Chapter 3 Generators General . . . . . . . . . . . . . . . . . . . . . . Ele Electr ctrical ical Char Charac actteri eristic sticss . . . . . . . . . . Generator Neu Neutral Grounding . . . . . . Generator Surge Protection . . . . . . . . Mech Mechan anic icaal Cha Charac racter teristi istics cs . . . . . . . . Excitation Systems . . . . . . . . . . . . . . Generator Stator . . . . . . . . . . . . . . . Rotor and Shaft . . . . . . . . . . . . . . . . Brakes and Jacks . . . . . . . . . . . . . . . Bearings . . . . . . . . . . . . . . . . . . . . . Temperature Dev Devices . . . . . . . . . . . . Fin Final Acce Accept ptan ancce Tes Tests . . . . . . . . . . . Fir Fire Supp Suppre ress ssiion Syst Systeems . . . . . . . . . Chapter 4 Power Transformers General . . . . . . . . . . . . . . . . . . . . . .
1-1 1-2 1-3 1-4 1-5 1-6 1-7
2-1 2-2 2-3 2-4 2-5
3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 -12 3-13 -13
4-1
Page
1-1 1-1 1-1 1-1 1-1 1-1 1-2
2-1 2-1 2-2 2-3 2-3
Subject
Paragraph
Rating . . . . . . . . . . . . . . . . . . . . . . . . Cooling . . . . . . . . . . . . . . . . . . . . . . . Elec Electtrica ricall Char Charac actteris eristi tics cs . . . . . . . . . . . . Terminals . . . . . . . . . . . . . . . . . . . . . . Accessories . . . . . . . . . . . . . . . . . . . . . Oil Containment Systems . . . . . . . . . . . Fire Suppression Systems . . . . . . . . . . .
Chapter 5 High Voltage System Definition . . . . . . . . . . . . . . . . . . . . . . Switchyard . . . . . . . . . . . . . . . . . . . . . Switching Scheme . . . . . . . . . . . . . . . . Bus Structures . . . . . . . . . . . . . . . . . . . Switchyard Materials . . . . . . . . . . . . . . Transformer Leads . . . . . . . . . . . . . . . . Powerhouse - Switchyard Power Control and Signal Leads . . . . . . . . . . Circuit Breakers . . . . . . . . . . . . . . . . . . Disconnect Switches . . . . . . . . . . . . . . . Surge Arr Arresters . . . . . . . . . . . . . . . . . .
Page
4-2 4-3 4-4 4-5 4-6 4-7 4-8
4-1 4-1 4-2 4-2 4-3 4-4 4-5 4-5
5-1 5-2 5-3 5-4 5-5 5-6
5-1 5-1 5-1 5-3 5-3 5-4
5-7 5-8 5-9 5-10
5-4 5-5 5-6 5-6
6-1 6-2 6-3 6-4
6-1 6-1 6-2 6-2 6-2 6-2
6-5
6-3 6-3
3-1 3-1 3-6 3-8 3-8 3-10 3-14 3-15 3-15 3-15 3-16 3-17 -17 3-18 -18
Chapter 6 Generator-Voltage System General . . . . . . . . . . . . . . . . . . . . . . . . Generator Leads . . . . . . . . . . . . . . . . . Neut Neutra rall Grou Ground ndiing Equi Equipm pmen entt . . . . . . . . Inst nstrum rument ent Tran Transf sfor orm mers ers . . . . . . . . . . . . Single Unit and Small Powe Powerr Pla Plant Con Consid sidera eration tionss . . . . . . . . . Excitation System Power Potential Transformer . . . . . . . . . . . . . Circuit Breakers . . . . . . . . . . . . . . . . . .
6-6 6-7
6-3 6-3
4-1
Chapter 7 Station Station Service Service System Power Supply . . . . . . . . . . . . . . . . . . . 7-1
7-1
i
EM 1110-2-3006 30 Jun 1994 Subject
Paragraph
Page
Subject
Relays . . . . . . . . . . . . . . . . . . . . . . Cont Contro roll and Mete etering ring Equi Equipm pmen entt . . . . Loa Load/Di d/Dist strribut ibutiion Cen Center ters . . . . . . . . . Esti Estima matted Stat Statiion Ser Service vice Loa Load . . . . .
7-2 7-3 7-3 7-4 7-4 7-5 7-5
7-3 7-3 7-3 7-3 7-3 7-3 7-3
Chapter 8 Control System General . . . . . . . . . . . . . . . . . . . . . . Control Equipment . . . . . . . . . . . . . . Turbine Governor . . . . . . . . . . . . . . Large Power Plant Control . . . . . . . . Small Power wer Plant Control . . . . . . . . Protective Relays . . . . . . . . . . . . . . . Aut Automa omatic tic Gen Genera eration tion Cont Contro roll . . . . . .
8-1 8-2 8-3 8-4 8-5 8-6 8-7 8-7
8-1 8-1 8-2 8-2 8-4 8-4 8-6 8-6
Chapter 9 Annunciation System General . . . . . . . . . . . . . . . . . . . . . . Audio and Visual Signals . . . . . . . . . Annunciator . . . . . . . . . . . . . . . . . . Sequ Sequen enttial ial Eve Events nts Reco Record rder er . . . . . . . . Trou Troubl blee Annu Annun ncia ciator tor Poi Points nts . . . . . . . . Chapter 10 Communication System General . . . . . . . . . . . . . . . . . . . . . . Voi Voice Com Communi unicat cation ion Syst System em . . . . . . Dedi Dedica cate ted d Comm Commun unic icat atio ions ns Syst System em . . Comm Commun unic icat atio ion n Syst System em Sele Select ctio ion n ...
9-1 9-2 9-3 9-4 9-4 9-5 9-5
10-1 10-2 10-2 10-3 10-3 10-4 10-4
9-1 9-1 9-1 9-2 9-2 9-2 9-2
10-1 1010-1 10-1 10-1 10-4 10-4
Paragraph
Page
Chapter 13 Grounding Systems General . . . . . . . . . . . . . . . . . . . . . Safety Hazards . . . . . . . . . . . . . . . Field Exploration . . . . . . . . . . . . . . Ground Mats . . . . . . . . . . . . . . . . . Powerhouse Gro Grounding . . . . . . . . . . Switchyard Grounding . . . . . . . . . . Grounding Devices . . . . . . . . . . . .
13-1 13-2 13-3 13-4 13-5 13-6 13-7
13-1 13-1 13-1 13-1 13-2 13-3 13-3
Chapter 14 Conduit and Tray Systems General . . . . . . . . . . . . . . . . . . . . . Conduit . . . . . . . . . . . . . . . . . . . . Cable Trays . . . . . . . . . . . . . . . . .
14-1 14-2 14-3
14-1 14-1 14-2
Chapter 15 Wire and Cable General . . . . . . . . . . . . . . . . . . . . . Cable Size . . . . . . . . . . . . . . . . . . Cab Cable System Classification . . . . . . Con Conduit and Cable Schedules . . . . .
15-1 15-2 15-3 15-4
15-1 15-1 15-1 15-2
Chapter 16 Procedure Procedure for Powerhouse Powerhouse Design Design Initiation . . . . . . . . . . . . . . 16-1 Design Process . . . . . . . . . . . . . . . 16-2
16-1 16-1
Chapter 17 General General Design Memorandum Requirements . . . . . . . . . . . . . . . .
17-1
17-1
Chapter 11 Direct-Current System General . . . . . . . . . . . . . . . . . . . . . . Batteries . . . . . . . . . . . . . . . . . . . . . Bat Battery tery--Char Charg ging ing Equi Equip pment ment . . . . . . . Inverter Sets . . . . . . . . . . . . . . . . . . Battery Swit witchboard . . . . . . . . . . . . .
11-1 11-2 11-3 11-3 11-4 11-5
11-1 11-1 1111-2 11-2 11-2
Chapter 12 Lighting Lighting and Receptacle Receptacle Systems Systems Design . . . . . . . . . . . . . . . . . . . . . . Illum llumin inat atio ion n Requ Requiireme rement ntss . . . . . . . . Efficiency . . . . . . . . . . . . . . . . . . . . Cond Conduc ucto torr Typ Types and Size Sizess . . . . . . . . Emer Emerge genc ncy y Ligh Lightt Con Control trol . . . . . . . . . Cont Contro roll Room Room Ligh Lightting ing . . . . . . . . . . . Haz Hazardo ardous us Area Area Ligh Lightting ing . . . . . . . . . Receptacles . . . . . . . . . . . . . . . . . . .
Chapter 18 Feature Design Memorandums and Drawings Design Memorandum Topics and Coverage . . . . . . . . . . . 18-1 Feature Design Memorandums . . . . 18-2 Engineering Doc Documentation . . . . . . 18-3 Design Drawings . . . . . . . . . . . . . . 18-4
18-1 18-1 18-1 18-1
12-1 12-2 12-2 12-3 12-4 12-4 12-5 12-5 12-6 12-6 12-7 12-7 12-8
12-1 1212-1 12-2 1212-2 1212-2 1212-3 1212-3 12-3
Chapter 19 Construction Specifications and Drawings Specifications . . . . . . . . . . . . . . . . 19-1 Con Construction Drawin wings . . . . . . . . . . 19-2
19-1 19-1
Chapter 20 Analysis of Design Permanent Record . . . . . . . . . . . . .
20-1
ii
20-1
EM 1110-2-3006 30 Jun 1994 Subject
Paragraph
Up-To-Date Values . . . . . . . . . . . . . Expansion . . . . . . . . . . . . . . . . . . . .
20-2 20-3
Page
20-1 20-1
Appendix A References . . . . . . . . . . . . . . . . . .
A-1
Appendix B Power Transformer Studies and Calculations Calculations . . . . . . . . . . . .
B-1
iii
EM 1110-2-3006 30 Jun 94
Chapter 1 Introduction
indica indicated ted to secure secure a degree degree of unifor uniformit mity y in plants plants of similar similar size and character. character. These preferred preferred designs designs should be followed unless unusual conditions make them unsuitable or unreasonably expensive.
1-1. 1-1. Purpos Purpose e
1-5. 1-5. Codes Codes
This manual provides guidance and assistance assistance to design design engineers in the development of electrical designs for new hydroe hydroelec lectri tricc power power plants. plants. The manual manual should should be used when preparing electrical designs for hydroelectric power plants plants for civil works facilities facilities built, owned, or operated operated by the Corps Corps of Engine Engineers ers.. Treatm Treatment ent of electr electrica icall syssystems tems for for pump pumped ed stor storag agee plan plants ts is not not cove covere red d in the the manual, although much of the information is applicable to pumped storage plant systems and subsystems.
Portio Portions ns of the codes, codes, standa standards rds,, or requir requireme ements nts pubpublished lished by the associ associati ations ons or agenci agencies es listed listed below below are appl applic icab able le to the the work work.. A comp comple lete te list listin ing g of code codes, s, stan standa dard rds, s, and and guid guides es is cont contai aine ned d in Appe Append ndix ix A, “References.”
American National Standards Institute (ANSI)
1-2. Applicability Applicability This manual is applicable to all civil works activities having responsibi responsibiliti lities es for the design design of hydroelect hydroelectric ric power plants.
rel related ated
Electric Power Research Institute (EPRI) Illuminating Engineering Society (IES) Nati Nation onal al (NEMA)
1-3. References References Requ Requiired red and and Appendix Appendix A.
Inst Instit itut utee of Elec Electr tric ical al and and Elec Electr tron onic icss Engi Engine neer erss (IEEE)
publ publiicat cation ions
are are
liste isted d
in
1-4. 1-4. Scope Scope a. Genera Generator tor rating rating. The manual manual presen presents ts good engiengi-
neering practice in designing electrical systems for hydroelectric power plants employing generating units of up to approximately 300 MW in in rating. b. Plant Plant feat feature uress. The manual manual deals deals with the elect electrirical features of hydroelectric power plants, and covers the generatin generating g equipment equipment,, station station service, service, various various switchyard switchyard and transm transmiss ission ion line line arrang arrangeme ements nts,, detail detailss of lighti lighting, ng, commun communica icatio tion n and contro control, l, and protec protectiv tivee device devicess for plant plant equipm equipment ent and relate related d auxili auxiliari aries. es. Genera Generator torss and power power transf transform ormers ers are treate treated d under under their their respec respectiv tivee headings, but other equipment, materials, and devices are discussed discussed under the distinct distinct functional functional systems systems in which they are used. c. Specification Specification preparation preparation. Informati Information on is presente presented d
to facili facilitat tatee the prepar preparati ation on of specif specifica icatio tions ns for major major items of equipment using pertinent approved guide specificati fications ons,, and specif specifica icatio tions ns for sugges suggested ted plant plant design design features which take into consideration the numerous ancillary and control details that are required to carry out the inte intend nded ed plan plantt func functi tion on.. Wher Wh eree alte altern rnat atee desi design gnss of functi functiona onall system systemss are discus discussed sed,, a prefer preferred red design design is
Elec Electr tric ical al
Manu Manufa fact ctur urer erss
Asso Associ ciat atio ion n
National Fire Protection Association (NFPA) Underwriters Laboratory (UL)
1-6. 1-6. Criteri Criteria a a. Preferred Preferred methods methods. The design design methods methods,, assumpassump-
tions, tions, electric electrical al characteri characteristics stics criteria, criteria, details, details, and other provis provision ionss covere covered d in this this manual manual should should be follow followed ed wherev wherever er practica practicable ble.. The manual manual was prepared prepared for use by engineers with basic knowledge of the profession, and judgment and discretion should be used in applying the material material contained contained herein. herein. In cases where preferred preferred alternatives are not identified, designers should follow recommendations mendations contained contained in the reference materials materials listed listed in the Bibliography that apply to the work to be performed. b. Deviati Deviations ons from prefer preferred red methods methods. Depa Depart rtur ures es from from thes thesee guid guides es may may be nece necess ssar ary y in some some case casess in order order to meet meet specia speciall requir requireme ements nts or condit condition ionss of the work under consider consideration ation.. When alternate alternate methods, methods, procedure cedures, s, and types types of equipm equipment ent are invest investiga igated ted,, final final sele select ctio ion n shou should ld not not be made made sole solely ly on firs firstt cost cost,, but but shou should ld be base based d on obta obtain inin ing g over overal alll econ econom omy y and and securi security ty by giving giving approp appropria riate te weight weight to reliab reliabili ility ty of service, ease (cost) of maintenance, and ability to restore serv servic icee with within in a shor shortt time time in even eventt of dama damage ge or abnormal abnormal circumstanc circumstances. es. Whether Whether architect-en architect-enginee gineers rs or
1-1
EM 1110-2-3006 30 Jun 94 Hydroelect Hydroelectric ric Design Design Center Center personnel personnel design design the power plant, the criteria and instructions set out in Appendix A of Guide Specification Specification CE-4000 should be followed. followed.
1-7. Hydroelectri Hydroelectric c Design Center Center (HDC) The engineering of hydroelectric projects is a highly specializ cialized ed field, field, partic particula ularly rly the engine engineeri ering ng design design and engineeri engineering ng support of operational operational activit activities. ies. In order to assi assist st fiel field d oper operat atin ing g acti activi viti ties es (FOA) (FOA),, the the Corp Corpss of Engineers has established the Hydroelectric Design Center (HDC) (HDC) as the center center of expert expertise ise in the Corps of EngiEngineer neerss for for this this work work.. The The FOA FOA will will reta retain in comp comple lete te responsibility and authority for the work, including funding, ing, insp inspec ecti tion on,, test testin ing, g, cont contra ract ct mana manage geme ment nt,, and and admi admini nist stra rati tion on.. The The HDC HDC will will perf perfor orm m the the foll follow owin ing g engineering and design services:
c. Prepare Prepare preliminary preliminary design design reports and the feature
design design memorandum memorandumss for hydroelect hydroelectric ric power plants for the requestin requesting g FOA. d . Prepar Preparee plans plans and specif specifica icatio tions ns for supply supply and
construction contracts and supplemental major equipment testing contracts. e. Provide Provide technical technical review review of shop drawings. drawings. f . Provid Providee techni technical cal assist assistanc ancee to the Contra Contracti cting ng
Office Officer’s r’s represe representa ntativ tivee at model and field tests. tests. The HDC will analyze results and make recommendations. g. Assist Assist in prepar preparati ation on of Operat Operation ion and Mainte Mainte--
nance Manuals. h. Provide Provide necessary necessary engineering engineering and computercomputer-aided aided
a. Provid Providee the techni technical cal portio portions ns of reconn reconnais aissan sance ce
reports and other pre-authorization studies for inclusion by the requesting FOA in the overall report.
drafti drafting ng (CAD) (CAD) work work to incorp incorpora orate te “as-bu “as-built ilt”” change changess into the electronically readable “record” drawing files, and assure complete coordination for such changes.
b. Provide Provide the architectural architectural,, structura structural, l, electrica electrical, l, and
i. Partic Participa ipate te in review review of plans plans and specif specifica icati tions ons
mechanica mechanicall design design for the powerhouse including including switchswitchyards, related facilities, and all hydraulic transient studies.
for non-Federa non-Federall developmen developmentt at Corps of Engineers Engineers pro jects in accordance with ER 1110-2-103.
1-2
EM 1110-2-3006 30 Jun 94
Chapter 2 Basic Switching Provisions
2-1. One-Line One-Line Diagram Diagrams s The The deve develo lopm pmen entt of a plan plantt elec electr tric ical al one-li one-line ne diagra diagram m should should be one of the first first tasks tasks in the preliminar preliminary y design of the plant. plant. In evaluating evaluating a plant for good electrical system design, it is easy to discuss system design in terms of the plant’s one-line electrical diagram. The relations relationship hip between between generators generators,, transform transformers, ers, transtransmissio mission n lines, lines, and source sourcess of statio station n servic servicee power power are established, along with the electrical location of the associated power circuit breakers and their control and protection tion functi functions ons.. The develop developmen mentt of the plant plant one-line one-line diagram and the switching arrangement required to implement the one-line may help determine the rating of generators and consequently the rating of the turbines and the size size of the the powe powerh rhou ouse se.. In deve develo lopi ping ng plan plantt oneone-li line ne diagram alternatives, use should be made of IEEE C37.2 to aid those reviewing the alternatives. a.
Gene Genera rall.
Some Some facto factors rs to consi conside derr in evaluatin evaluating g one-line one-line diagrams diagrams and switching switching arrangeme arrangements nts includ includee whethe whetherr the plant plant will will be manned manned or unmann unmanned, ed, equipment reliability, whether the plant will be used in a “peaking” versus a base load mode of operation, the need to mainta maintain in a minimu minimum m flow flow past past the plant, plant, or whethe whetherr there is a restriction on the rate of change of flow past the plant. plant. The base load load mode implies implies a limite limited d number number of unit unit startstart-sto stop p operat operation ions, s, and fewer fewer breake breakerr operat operation ionss than would be required required for peaking peaking operation. operation. Unmanned Unmanned oper operat atio ion n indi indica cate tess a need need for for reli reliab able le prot protec ecti tion on and and contro control, l, and simplic simplicity ity of operat operation ion.. If there there are severe severe flow flow rest restri rict ctio ions ns,, coup couple led d with with a need need for for cont contin inuo uous us reliable power output, it may be necessary to consider the “unit” “unit” arrangeme arrangement nt scheme scheme because because it provides provides the miniminimum los loss of gene genera rattion dur during ing first irst cont contin inge genc ncy y disturbances. b.
Evalua Evaluation tion factor factorss.
In gene genera ral, l, a good good plan plantt electr electrica icall one-li one-line ne should should be develope developed d with with the goal of achieving the following plant characteristics: c.
Design Design charac character terist istics ics.
(1) Safety Safety and reliabili reliability. ty. (2) Simplici Simplicity ty of operation. operation. (3) Good technical technical perform performance. ance.
(4) Readil Readily y mainta maintaina inable ble (e.g., (e.g., critic critical al compon component entss can be remove removed d from from servic servicee withou withoutt shutti shutting ng down down the balance of plant). (5) Flexibili Flexibility ty to deal with contingencies contingencies.. (6) Ability Ability to accommodate accommodate system system changes.
2-2. 2-2. Plant Plant Scope Scope a. Exte Extent nt of proj projec ect t .
When When conside considerin ring g switchi switching ng scheme schemes, s, there there are two basic basic power power plant plant develo developme pment nt scopes. scopes. Either Either the project scope scope will include include a transmistransmission-voltage switchyard associated with the plant or, electrically, the project scope ends at the line terminals of the high-voltage disconnect switch isolating the plant from the transm transmiss ission ion line. line. Freque Frequentl ntly, y, the Corps of Engine Engineers ers project scope limit is the latter situation with the interconnecting switchyard designed, constructed, and operated by the Federa Federall Power Power Market Marketing ing Agency Agency (PMA), (PMA), wieldi wielding ng the power or by the public public utilit utility y purcha purchasin sing g the power through the PMA. Whethe Whet herr or not not the the scope scope includ includes es a switch switchyar yard, d, the one-li one-line ne develo developme pment nt will will involv involvee the switch switching ing arrang arrangeme ement nt of the units, units, the number number of units units on the generato generatorr step-u step-up p (GSU) (GSU) transtransformer former bank, bank, and the arrang arrangeme ement nt of power power equipm equipment ent from from the generato generatorr to the low voltag voltagee termin terminals als of the GSU transfo transforme rmer. r. This This equipm equipment ent is medium medium-vo -volta ltage ge (0.6 kv-15 kV ) ele electr ctrical ical equi equipm pmen entt. Thi This chap chaptter descri describes bes select selection ion of approp appropria riate te switch switching ing scheme schemes, s, includ including ing develo developme pment nt of equipm equipment ent rating ratings, s, econom economic ic factors, factors, and operational operational considerat considerations. ions. Chapter Chapter 6, “Generator erator Voltag Voltagee System System,” ,” descri describes bes equipm equipment ent types types and application considerations in selecting the medium-voltage equipment equipment used in these systems. systems. Switching Switching schemes schemes for genera generatin ting g units units and transf transform ormers ers may be of either either the indoor or outdoor type, or a combination of both. b.
Medium Medium-vol -voltag tagee equipmen equipment t .
c. High-voltage High-voltage equipme equipment. nt. When development does
includ includee a switch switchyar yard d or substa substatio tion, n, the same same consid considera era-tions apply in developing the generator voltage switching schemes described in paragraph 2-2 b. Combined Combined developdevelopment does provide the opportunity to apply cost and technical trade-offs trade-offs between between the medium-vol medium-voltage tage systems systems of the the powe powerr plan plantt and and the the high high-v -vol olta tage ge syst system emss of the the switchyard switchyard.. Chapter Chapter 5, “High-Volt “High-Voltage age System,” describes describes switchyard arrangements, equipment and application considera sideratio tions ns in develo developin ping g the switch switchyar yard d portio portion n of the
2-1
EM 1110-2-3006 30 Jun 94 one-line one-line diagram. Switchyard Switchyardss are predominatel predominately y outdoor outdoor inst nstalla allattion ions alth altho ough ugh in spe specia cial case casess (e.g e.g., an underg undergrou round nd power power plant) plant) high-v high-volt oltage age SF 6 insulated equipment systems may find use.
higher in first cost than schemes that have multiple generator atorss on a sing single le tran transf sfor orme merr and and tran transm smis issi sion on line line.. Medium-vo Medium-voltage ltage equipment equipment for the unit systems systems includes includes bus leads from the generator to the GSU transformer and isolation disconnects for maintenance purposes.
2-3. Unit Switching Switching Arrangeme Arrangements nts b. Multiple unit arrange arrangements ments. a. “Unit” “Unit” arrang arrangeme ement nt .
A “uni “unit” t” sche scheme me show showin ing g outdoor outdoor switching switching of the generator and transforme transformerr bank as a unit on the high-voltage side only, is shown in Figure 2-1a 2-1a.. The unit scheme scheme is well-s well-suit uited ed to small small power syst system emss wher wheree loss loss of larg largee bloc blocks ks of gene genera rati tion on are are diffic difficult ult to tolerate tolerate.. The loss loss of a transf transform ormer er bank or transm transmiss ission ion line line in all other other arrang arrangeme ements nts would would mean mean the the loss loss of more more than a sing single le genera generati tion on unit unit.. Smal Smalll power systems are systems not able to compensate for the loss of multiple units, as could occur using other arrangements. ments. The “unit” “unit” scheme scheme makes makes mainte maintenan nance ce outages outages simpler to arrange and is advantageous where the plant is locate located d near near the high-v high-volt oltage age substa substatio tion n making making a short short transm transmiss ission ion distan distance. ce. This This scheme scheme,, with with a transf transform ormer er and transmission line for each generator unit, tends to be
Figure Figure 2-1. Main unit switching switching schemes schemes
2-2
(1) (1) In larg larger er powe powerr syst system ems, s, wher wheree loss loss of larg larger er blocks of generation may be tolerable or where the plant is interconnected to an EHV grid (345 kV and and above), two or more more genera generator torss togeth together er with with their their transf transform ormer er (or transf transform ormer er bank) bank) may be connec connected ted to one switch switchyar yard d positi position. on. Some Some of the common commonly ly used schemes schemes are discussed cussed in the followi following ng paragrap paragraphs. hs. Refer Refer to Chapte Chapterr 3, “Generators” for discussion on the protection requirements for generator arrangements. (2) (2) Two Two gene genera rato tors rs may may be conn connec ecte ted d to a twotwowinding winding transform transformer er bank through through Medium-Vol Medium-Voltage tage Circuit cuit Breake Breakers rs (MVCBs) (MVCBs) as shown on Figure Figure 2-1b. 2-1b. This This arrangement has the advantage of requiring a single transmission line for two units, rather than the two lines that would would be requir required ed for a “unit” “unit” arrang arrangeme ement. nt. This This proprovide videss a clea clearr savi saving ngss in line line righ rightt-of of-w -way ay cost cost and and maintenanc maintenance. e. A single transformer transformer,, even though of higher higher rating rating,, is also also less less costly costly than the two transf transform ormers ers that that would would be needed needed for a “unit” “unit” system system.. Again, Again, the space space requireme requirement nt is also less than for two separate separate transformtransformers. ers. There There are trade trade-of -offs: fs: an MVCB MVCB for each each generat generator or is needed, the generator grounding and protection scheme becomes becomes more complex, complex, and additional additional space and equipequipment are needed for the generator medium-voltage (delta) bus. bus. An econ econom omic ic study study shou should ld be made made to justif justify y the the choice of design, and the transformer impedance requirements should be evaluated if the power system is capable of delivering a large contribution to faults on the generator side of the transformer. (3) (3) For For smal smalll gene genera rati ting ng plan plants ts,, a sche scheme me which which connects the generators through MVCBs to the generator bus bus is shown shown in Figu Figure re 2-1c. 2-1c. One One or more more GSU GSU tran transsformers can be connected to the bus (one is shown), with or with withou outt circ circui uitt brea breake kers rs;; howe howeve ver, r, use use of mult multip iple le transformers, each with its own circuit breaker, results in a very flexible operatin operating g arrangement. arrangement. Individua Individuall transformers can be taken out of service for testing or maintenance without without taking taking the whole plant out of service. service. The impedances of the transformers must be matched to avoid circ circul ulat atin ing g curr curren ents ts.. As note noted d abov above, e, the the prot protec ecti tion on scheme scheme becomes becomes more more comple complex, x, but this this should should be conconsidere sidered d along along with with the other other tradetrade-off offss when when compar comparing ing this scheme with the other plant arrangements possible.
EM 1110-2-3006 30 Jun 94 (4) (4) Two Two or more more gene genera rato tors rs can can be conn connec ecte ted d to individua individuall transforme transformerr banks through through generator generator MVCBs with the transform transformers ers bused through disconnect disconnect switches on the high-vol high-voltag tagee side side as shown shown in Figure Figure 2-1d. 2-1d. This This arrang arrangeme ement nt has some some of the advant advantage agess of the “unit” “unit” system shown in Figure 2-1a, and discussed above, along with with the advant advantage age of fewer fewer transm transmiss ission ion lines, lines, which which result resultss in less right-o right-of-w f-way ay needs. needs. There There is some some loss loss of operat operation ional al flexib flexibili ility, ty, since since transm transmiss ission ion line line servic servicee requires taking all of the units out of service, and a line fault will result in sudden loss of a rather large block of power. power. Again, Again, needs of the bulk power power distri distribut bution ion system tem and and the the econ econom omic icss of the the arra arrang ngem emen entt must must be considered. (5) (5) Two Two or more more gene genera rato tors rs may may be conn connec ecte ted d to a three-wind three-winding ing transform transformer er bank as shown in Figure Figure 2-1e 2-1e and and f. The The gene genera rato tors rs would would be conne connect cted ed to the the two two low-vo low-volta ltage ge windin windings gs throug through h genera generator tor MVCBs. MVCBs. This This arra arrang ngem emen entt allo allows ws spec specif ific icat atio ion n of a low low valu valuee of “through” impedance thus increasing the stability limits of the system and allowing the specification of a high value of impeda impedance nce betwee between n the two low-vo low-volta ltage ge GSU transtransformer former windings. windings. This reduces reduces the interrupti interrupting ng capacity capacity requir requireme ements nts of the generato generatorr breake breakers. rs. This This scheme scheme is partic particula ularly rly advisa advisable ble when when the plant plant is connec connected ted to a bulk power distribution system capable of delivering high fault currents currents.. Again, transform transformer er or line faults faults will result in the potential loss to the bulk power distribution system of a relati relativel vely y large large block of genera generati tion. on. Transf Transform ormer er maintenance or testing needs will require loss of the generatin erating g capaci capacity ty of all four units units for the durati duration on of the test or maintenance maintenance outage. outage. This scheme scheme finds application application where plants are interconnected directly to an EHV grid.
2-4. Substation Substation Arrangem Arrangements ents a. Genera Generall.
High-v High-volt oltage age substa substatio tion n arrangem arrangement entss and application considerations are described in Chapter 5, “High“High-Vol Voltag tagee System System.” .” High-v High-volt oltage age system systemss includ includee those systems rated 69 kV and and above. above. The plant plant switchswitching arrangement arrangement should be coordinat coordinated ed with the switchswitchyard arrangement arrangement to ensure ensure that the resulting resulting integration integration achieves the design goals outlined in paragraph 2-1 c in a cost-effective manner. b. Substation Substation switching switching. Some Some plants plants may be electr electriically cally locate located d in the power power system system so their their transm transmiss ission ion line-v line-volt oltage age buses buses become become a connec connectin ting g link link for two or more lines lines in the power system network. network. This can require require an appreciabl appreciablee amount amount of high-volta high-voltage ge switching switching equipequipment. ment. The desirabilit desirability y of switching switching small small units at generator voltag voltagee should should nevert neverthel heless ess be invest investiga igated ted in such such
case cases. s. Chap Chapte ters rs 5, “Hig “Highh-Vo Volt ltag agee Syst System em”” and and 6, “Generator “Generator-Volt -Voltage age System,” System,” discuss discuss switching switching and bus arrangements in more detail.
2-5. Fault Current Current Calculat Calculations ions a. Genera Generall.
Faul Faultt curr curren entt calc calcul ulat atio ions ns,, usin using g the the method method of symmetri symmetrical cal components components,, should should be prepared prepared for each one-line scheme evaluated to determine required transform transformer er impedance impedances, s, generator generator and station station switchgear switchgear breake breakerr interr interrupt upting ing rating ratings, s, and rating ratingss of discon disconnec nectt switches switches and switchyard switchyard components. components. Convention Conventional al methods of making the necessary fault current calculations and of determ determini ining ng the requir required ed rating ratingss for equipm equipment ent are discus discussed sed in IEEE 242 and 399. A number number of softwa software re programs are commercially available for performing these studie studiess on a person personal al computer computer.. Two of these these programs programs are: ETAP, from Operation Technology, Inc., 17870 Skypark park Circle Circle,, Suite Suite 102, 102, Irvine Irvine,, CA 92714; 92714; and DAPPER DAPPER and and A-FA A-FAUL ULT, T, from from SKM SKM Syst System emss Anal Analys ysis is,, Inc. Inc.,, 225 225 S Sepu Sepulv lved edaa Blvd Blvd,, Suit Suitee 350, 350, Manh Manhat atta tan n Beac Beach, h, CA 90266. b. Criteri Criteria a.
The The foll follow owin ing g crit criter eria ia shoul should d be folfollowe lowed d in dete determ rmin inin ing g valu values es of syst system em shor shortt-ci circ rcui uitt capacity, capacity, power transform transformer er impedances impedances,, and generator generator reactances to be used in the fault current calculations. (1) (1) Syst System em shor shortt-ci circ rcui uitt capa capaci city ty.. This This is the the estim estimate ated d maximu maximum m ultima ultimate te symmet symmetric rical al kVA shortcircuit capacity available at the high-voltage terminals of the GSU transf transform ormer er connec connected ted to the genera generator tor under under consideration, or external to the generator under consideration ation if no step-up step-up transf transform ormer er is used. It include includess the short-circuit capacity available from all other generators in the power plant in addition to the short-circuit capacity of the the high high-v -vol olta tage ge tran transm smis issi sion on syst system em.. Syst System em shor shorttcircuit circuit capacity capacity is usually usually readily readily available available from system system planners of the utility or the PMA to which the plant will be connected. (2) Calcul Calculati ating ng system system short-ci short-circu rcuit it capaci capacity. ty. The transm transmiss ission ion system system shortshort-cir circui cuitt capaci capacity ty can also also be calculated with reasonable accuracy when sufficient information regarding the planned ultimate transmission system is available available,, including including the total total generating generating capacity capacity connected nected to the system system and the impeda impedance ncess of the various various transm transmiss ission ion lines lines that that provid providee a path path from from the energy energy sources to the plant. (3) (3) Esti Estima mati ting ng powe powerr syst system em faul faultt cont contri ribu buti tion on.. When When adequa adequate te inform informati ation on regard regarding ing the transm transmiss ission ion system system is unavailab unavailable, le, estimati estimating ng methods methods must be used.
2-3
EM 1110-2-3006 30 Jun 94 In all cases, cases, the system system shortshort-cir circui cuitt capaci capacity ty for use in the fault fault curren currentt calcul calculati ations ons should should be estima estimated ted on a cons conser erva vati tive ve basi basis, s, i.e. i.e.,, the the esti estima mate te shou should ld be larg largee enough to allow for at least a 50-percent margin of error in the system system contrib contributi ution. on. This This should should provide provide a factor factor of safety, and also allow for addition of transmission lines and generation capacity not presently planned or contemplated plated by system engineers engineers and planners planners.. Only in exceptional cases, such as small-capacity generating plants with only one or two connecting transmission lines, should the estimate estimated d ultimate ultimate system system short-cir short-circuitr cuitry y capacity capacity be less than 1,000 MVA. (4) Power transfor transformer mer impedances impedances.. (a) Ac Actual test values of power transformer impeda impedance ncess should should be used used in the fault fault calcul calculati ations ons,, if they are available. available. If test values values are not available, available, design values values of impeda impedance nce,, adjust adjusted ed for maximu maximum m IEEE IEEE stanstandard minus tolerance tolerance (7.5 percent percent for two-winding two-winding transtransformer formers, s, and 10 percen percentt for threethree-win windin ding g transf transform ormers ers and auto-tra auto-transf nsform ormers ers)) should should be used. used. Nomina Nominall design design impeda impedance nce values values are contai contained ned in Table Table 4-1 of ChapChapter 4, 4, “Power Transforme Transformers.” rs.” For example, example, if the impedance ance of a twotwo-wi wind ndin ing g tran transf sfor orme merr is spec specif ifie ied d to be 8.0 perc percent ent,, subjec subjectt to IEEE IEEE tolera tolerance nces, s, the transf transform ormer er will will be designed designed for 8.0 percen percentt impeda impedance nce.. Howeve However, r, the test impedance may be as low as 8.0 percent less a 7.5-percent tolerance, or 7.4 percent, and this lower value should be used in the calculations, since the lower value of impedance gives greater fault current. (b) (b) If the the impe impeda danc ncee of the the abov abovee exam exampl plee tran transsformer former is specif specified ied to be not more than 8.0 percent, percent, the transformer will be designed for 7.44 percent impedance,
2-4
so that the upper impedance value could be 7.998 percent, and the lower impedance value (due to the design tolerance) could be as low as 6.88 percent, which is 7.44 percent less the 7.5 percent tolerance, which should be used in the calculations because the lower value gives a higher fault current current.. Using the lower lower impedance impedance value value is a more cons conser erva vati tive ve meth method od of esti estima mati ting ng the the faul faultt curr curren ent, t, becaus becausee it anticipa anticipates tes a “worst “worst case” case” condit condition ion.. ImpedImpedances for three-wind three-winding ing transform transformers ers and auto-trans auto-transformformers ers shou should ld also also be adju adjust sted ed for for stan standa dard rd tole tolera ranc ncee in accordance accordance with the above above criteria. criteria. The adjusted adjusted impedance should then be converted to an equivalent impedance for use in the sequence networks in the fault current calculations. culations. Methods Methods of calculating calculating the equivalent equivalent impedimpedances and developing equivalent circuits are described in IEEE 242. (5) (5) Gene Genera rato torr reac reacta tanc nces es.. Actu Actual al test test valu values es of genera generator tor reacta reactance ncess should should also also be used used in the calcul calculaations if they are available available.. If test values values are not available, available, calculated values of reactances, obtained from the generator manufa manufactu cturer rer and adjust adjusted ed to the approp appropria riate te MVA base, should should be used. Rated-volt Rated-voltage age (saturate (saturated) d) values of the direct direct-ax -axis is transi transient ent reacta reactance nce (X’ d), the direct direct-ax -axis is subtransie subtransient nt reactance reactance (X"d), and the negati negativeve-seq sequen uence ce reactance (X 2), and the zero-sequence reactance (X o), are the four generator reactances required for use in the fault current current calculation calculations. s. If data are not available, available, Figure Figure 3-2 in Chapte Chapterr 3, “Gener “Generato ators, rs,”” provid provides es typica typicall values values of rated-vol rated-voltage tage direct-ax direct-axis is subtransie subtransient nt reactance reactance for waterwaterwhee wheell gene genera rato tors rs base based d on mach machin inee size size and and spee speed. d. Design reactance values are interrelated with other specified machine values (e.g., short-circuit ratio, efficiency) so revise revised d data data should should be incorp incorpora orated ted into into fault fault comput computaations once a machine has been selected.
EM 1110-2-3006 30 Jun 94
Chapter 3 Generators
3-1. 3-1. Genera Generall a. Design Design constr constrain aints ts.
Alm Almost ost all all of the hydra ydraul uliicturbine-driven generators used in Corps’ powerhouses will be synchronou synchronouss alternati alternating-cu ng-current rrent machines, machines, which produce electrical electrical energy energy by the transforma transformation tion of hydraulic hydraulic ener energy gy.. The The elec electr tric ical al and and mech mechan anic ical al desi design gn of each each generator generator must conform conform to the electrical electrical requireme requirements nts of the power distri distribut bution ion system system to which which it will will be conconnect nected ed,, and and also also to the the hydr hydrau auli licc requ requir irem emen ents ts of its its specif specific ic plant. plant. Genera Generall Corps Corps of Engine Engineers ers waterwh waterwheel eel generator design practice is covered by the Guide Specification CW-16210.
should should have sufficient sufficient continuous continuous capacity capacity to handle handle the maxi maximu mum m hors horsep epow ower er avai availa labl blee from from the the turb turbin inee at 100-percent gate without the generator exceeding its rated namepl nameplate ate tempera temperatur turee rise. rise. In determ determini ining ng genera generator tor capacity, any possible future changes to the project, such as raising the forebay level and increasing turbine output capa capabi bili lity ty,, shou should ld be cons consid ider ered ed.. Figu Figure re 3-1 3-1 show showss a typical capability curve for a hydroelectric generator.
b. Design characte characteristics ristics.
Since Since waterw waterwhee heell generagenerators tors are custom custom design designed ed to match match the hydrau hydraulic lic turbin turbinee prime prime mover, mover, many of the generator characteris characteristics tics (e.g., short-circuit ratio, reactances) can be varied over a fairly wide range, depending on design limitations, to suit specific cific plant plant requir requireme ements nts and power power distri distribut bution ion system system stabil stability ity needs. needs. Deviat Deviation ionss from from the nominal nominal genera generator tor design parameters can have a significant effect on cost, so a carefu carefull evalua evaluatio tion n of specia speciall featur features es should should be made made and and only only used used in the the desi design gn if thei theirr need need just justif ifie iess the the increased cost.
3-2. Electrical Electrical Characteris Characteristics tics a. Capaci Capacity ty and power factor factor . Genera Generator tor capa capacit city y is commonly expressed in kilovolt-amperes ( kVA), at a given
Figure Figure 3-1. Typical Typical hydro-generato hydro-generatorr capability curve
(“rate (“rated”) d”) power power factor factor.. The power power factor factor the generato generatorr will be designed for is determined from a consideration of the electrical electrical requirement requirementss of the power distribution distribution system it will be connected connected to. These requirem requirements ents include include a considera consideration tion of the anticipat anticipated ed load, load, the electrica electricall location of the plant relative to the power system load centers, and the transmiss transmission ion lines, lines, substatio substations, ns, and distribut distribution ion facilitie facilitiess involved. involved. (See paragraph paragraph 3-2 f ). ).
The The voltag voltagee of larg large, e, slowslowspee speed d gene genera rato tors rs shou should ld be as high high as the the econ econom omy y of machin machinee design design and the availa availabil bility ity of switch switching ing equipequipment ment permit permits. s. Genera Generator torss with with voltag voltagee rating ratingss in excess excess of 16.5 16.5 kV have have been been furnis furnished hed,, but except except in specia speciall cases, cases, manufactu manufacturing ring practices practices generally generally dictate dictate an upper volt voltag agee limi limitt of 13.8 13.8 kV for for mach machin ines es up thro throug ugh h 250 MVA rating. rating. Based on required required generator generator reactances, reactances, 2 size, and Wk , a lower generator voltage, such as 6.9 kV , may be necess necessary ary or prove prove to be more more econom economica icall than than higher higher voltage voltages. s. If the genera generator torss are to serve serve an estabestablished lished distribut distribution ion system system at generator generator voltage, then the system system voltag voltagee will will influe influence nce the select selection ion of genera generator tor voltage, and may dictate the selection and arrangement of genera generator tor leads leads also. also. Genera Generator torss of less than 5,000 kVA shou should ld pref prefer erab ably ly be desi design gned ed for for 480 480 V, V, 2,40 2,400 0 V, or 4,160 V, depending on the facilities connecting the generator to its load.
b. Gene Genera rato torr powe powerr outp output ut ratin rating g.
The ki kilowat watt rati rating ng of the the gene genera rato torr shou should ld be comp compat atib ible le with with the the hors horsep epow ower er rati rating ng of the the turb turbin ine. e. The The most most comm common on turb turbin inee type typess are are Fran Franci cis, s, fixe fixed d blad bladee prop propel elle ler, r, and and adjustabl adjustablee blade propeller propeller (Kaplan). (Kaplan). See detailed detailed discussion on turbine types and their selection and application in EM 1110-2-4205. 1110-2-4205. Each turbine turbine type has different different operatoperating characteristics and imposes a different set of generator design design criter criteria ia to correc correctly tly match match the genera generator tor to the turb turbin ine. e. For For any any turb turbin inee type type,, howe howeve ver, r, the the gene genera rato torr
c.
Genera Generator tor voltag voltagee.
3-1
EM 1110-2-3006 30 Jun 94 d. Insula Insulation tion.
(1) The generator generator stator stator winding is normally normally supplied supplied with either Class B or Class F insulation materials, with the insulation insulation system meeting the temperatu temperature re limits limits and para parame mete ters rs of ANSI ANSI C50. C50.12 12 (e.g (e.g., ., 75 °C rise rise abov abovee a 40 °C ambient) ambient).. The choice choice of insula insulatio tion n system system types types depe depend ndss on mach machin inee size size,, how how the the mach machin inee will will be operat operated, ed, and desire desired d windin winding g life. life. Modern Modern hydro hydro units units are subjected to a wide variety of operating conditions but spec specif ific icat atio ions ns shou should ld be prep prepar ared ed with with the the inte intent nt of achieving a winding life expectancy of 35 or more years under anticipated operating conditions.
wind windin ing g is of the the Roeb Roebel el bar bar type type.. Epox Epoxy y is usua usuall lly y preferred because of its higher T g, and the polyester insulation system may not be available in the future. (5) Thermo Thermoset settin ting g insula insulatio tion n system system materi materials als are hard and do not readily conform to the stator slot surface, so special special technique techniquess and careful careful installat installation ion procedures procedures must must be used in applyi applying ng these these materi materials als.. Corps Corps guide specif specifica icatio tion n CW-162 CW-16210 10 provid provides es guidan guidance ce on types types of winding winding and coil fabricatio fabrication n technique techniques, s, and installat installation, ion, accept acceptanc ance, e, and mainte maintenan nance ce proced procedure uress to be used used to ensure long, trouble-free winding life. e. Short-circui Short-circuitt ratio ratio.
(2) The choice choice between between Class B or Class F insula insulatio tion n syst system emss for for the the stat stator or wind windin ing g will will depe depend nd on the the expect expected ed use of the generato generator. r. If it will will be operate operated d concontinuously at or near rated load, or has a high probability of operat operating ing overload overloaded ed for longer longer than than 2 hr at a time, time, then then the Class Class F insula insulatio tion n system system should should be specif specified ied.. For generators that can be expected to be operated below rated load most of the time, and at or near full load for only only limite limited d period periods, s, a Class Class B insula insulatio tion n system system would would be satisf satisfact actory ory.. An insula insulatio tion n system system using using a polyes polyester ter resin as a binder should be considered a Class B system, since the softening temperature of polyester resin is close to the Class F temperature limit. (3) (3) Stat Stator or wind windin ing g insu insula lati tion on syst system emss cons consis istt of a groundwall insulation, usually mica, with a suitable insulation binder, generally a thermosetting epoxy or polyester material material.. These thermosett thermosetting ing systems systems achieve achieve dielectric dielectric strengths equivalent to that of older thermoplastic insulation tion system systemss with with less less thickn thickness ess than than the older older system systems, s, allowi allowing ng the use of additi additiona onall copper copper in a given given stator stator slot, slot, achieving achieving better heat transfer, transfer, and permitting permitting cooler operat operation ion.. Therm Thermose osetti tting ng insula insulatio tion n system systemss tolera tolerate te higher higher continuous continuous operating temperatures temperatures than older systems with less mechanical deterioration. (4) Polyester Polyester resin has a lower softening softening temperatur temperaturee (known (known as the glass glass transi transitio tion n temper temperatu ature, re, T g) than the more commonly available epoxy insulation system, but it has the advantage of being slightly more flexible than the epox epoxy y syst system em.. This This slig slight ht flex flexib ibil ilit ity y is an adva advant ntag agee when when instal installin ling g multimulti-tur turn n coils coils in stator stator slots slots in small small diameter diameter generators generators.. The plane of the coil side coincides coincides with with the plane plane of the slot slot once once the coil coil is instal installed led.. DurDuring installation, however, the coil side approaches the slot at a slight angle so that the coil must be slightly distorted to make the side enter enter the slot. slot. Polyes Polyester ter is less likely likely to fractu fracture re than than epoxy epoxy when when distor distorted ted during during instal installat lation ion.. Poly Polyes este terr has has no adva advant ntag agee over over epox epoxy y if the the stat stator or
3-2
(1) The short-circu short-circuit it ratio of a generator generator is the ratio of the field current required to produce rated open circuit voltag voltage, e, to the field field curren currentt requir required ed to produc producee rated rated stator stator curren currentt when when the genera generator tor output output termin terminals als are short-cir short-circuite cuited. d. The short-circu short-circuit it ratio is also the reciproreciprocal cal of the the per per unit unit valu valuee of the the satu satura rate ted d sync synchr hron onou ouss reactance. reactance. The short-circu short-circuit it ratio of a generator is a measure of the transient stability of the unit, with higher ratios providing providing greater greater stability. stability. Table 3-1 lists nominal nominal shortcircui circuitt ratios ratios for genera generator tors. s. ShortShort-cir circui cuitt ratios ratios higher higher than than nomi nomina nall valu values es can can be obta obtain ined ed with withou outt much much increase in machine size, but large values of short-circuit ratio must be obtained by trade-offs in other parameters of generator generator performanc performance. e. Increasin Increasing g the short-circu short-circuit it ratio above above nomina nominall values values increa increases ses the genera generator tor cost cost and decr decrea ease sess the the effi effici cien ency cy and and the the tran transi sien entt reac reacta tanc nce. e. Included in Table 3-1 are expected price additions to the gene genera rato torr basi basicc cost cost and and redu reduct ctio ions ns in effi effici cien ency cy and and transient reactance when higher than nominal short-circuit ratio values are required. required. (2) In genera general, l, the require requiremen mentt for other other than than nominominal shortshort-cir circui cuitt ratios ratios can be determ determine ined d only only from from a stability study of the system on which the generator is to operate. operate. If the stability stability study shows that generators generators at the electr electrica icall locati location on of the plant plant in the power power system system are likely likely to experi experienc encee instab instabili ility ty proble problems ms during during system system disturbances, then higher short-circuit ratio values may be determ determine ined d from from the model model studie studiess and specifi specified. ed. If the power plant design is completed completed and the generators generators purchased chased prior prior to a determ determina inatio tion n of the exteri exterior or system system connections and their characteristics, i.e., before the connecting transmission lines are designed or built, this will preclude preclude making a system system study to accurately accurately determine determine the short-circ short-circuit uit ratio required. required. Where it is not feasible to determine determine the short-circ short-circuit uit ratio and there there are no factors factors indica indicatin ting g that that higher higher than than nomina nominall values values are needed needed,, then nominal short-circuit ratios should be specified.
EM 1110-2-3006 30 Jun 94 Table 3-1 Generator Short-Circuit Ratios Short-Circuit Ratios at
Normal Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More Not More
Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than Than
0.8PF
0.9PF
0.95PF
1.00 1.08 1.15 1.23 1.31 1.38 1.46 1.54 1.62 1.70 1.76 1.83 1.89 1.96 2.02 2.08 2.13 2.19 2.24 2.30 2.35 2.40 2.45 2.50
1.10 1.22 1.32 1.42 1.52 1.59 1.67 1.76 1.84 1.92 1.98 2.05 2.11 2.18 2.24 2.30 2.35 2.40 2.45 2.51 2.56 2.61 2.66 2.71
1.07 1.32 1.46 1.58 1.70 1.78 1.86 1.96 2.03 2.11 2.17 2.24 2.30 2.37 2.42 2.48 2.53 2.58 2.63 2.69 2.74 2.79 2.83 2.88
1.0PF
f. Line-charging and condensing capacities. Nomi Nomina nall values values for these generator generator character characteristi istics cs are satisfact satisfactory ory in all except except very very specia speciall cases. cases. If the generato generatorr will be requir required ed to energi energize ze relati relativel vely y long long EHV transm transmiss ission ion lines, the line-charging requirements should be calculated and a generator generator with the proper proper character characteristic isticss specified. specified. The line-char line-charging ging capacity capacity of a generator generator having normal characteristics can be assumed to equal 0.8 of its normal rating rating multiplied multiplied by its short-circui short-circuitt ratio, ratio, but cannot be assumed to exceed its maximum rating for 70 °C temperature rise. rise. Often it will be desirable desirable to operate operate generators generators as synchronous synchronous condenser condensers. s. The capacity capacity for which they are designed when operating over-excited as condensers is as follows, unless different values are specified:
Power Factor .80 .90 .95 1.00
Condenser Capacity 65 55 45 35
percent percent percent percent
1.25 1.43 1.60 1.75 1.88 1.97 2.06 2.16 2.23 2.31 2.37 2.44 2.50 2.56 2.61 2.67 2.72 2.77 2.82 2.87 2.92 2.97 3.01 3.06
Price Addition (Percent of Basic Price) 0 2 4 6 8 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 37.5 40 42.5 45 47.5 50 52.5 55
Reduction in Full-Load Efficiency 0. 0 0. 1 0. 2 0. 2 0. 3 0. 3 0. 4 0. 4 0. 4 0. 4 0. 5 0. 5 0. 5 0. 5 0. 6 0. 6 0. 6 0. 6 0. 7 0. 7 0. 7 0. 7 0. 7 0. 7
Multiplier For Transient Reactance 1 . 0 00 0 . 9 70 0 . 9 40 0 . 9 10 0 . 8 90 0 . 86 0 0 . 82 5 0 . 79 0 0 . 76 0 0 . 73 0 0 . 70 5 0 . 68 0 0 . 65 5 0 . 63 0 0 . 60 5 0 . 58 0 0 . 56 0 0 . 54 0 0 . 52 0 0 . 50 0 0 . 48 0 0 . 46 0 0 . 44 5 0 . 43 0
g. Power Power factor factor..
(1) The heat generat generated ed within within a machin machinee is a funcfunction of its kVA output; the capacity rating of a generator is usua usuall lly y expr expres esse sed d in term termss of kVA and power power factor factor.. (Large (Largerr machin machinee rating ratingss are usuall usually y given given in MVA for convenienc convenience.) e.) The kilowatt kilowatt rating rating is the kVA rating multiplied plied by the rated power factor. factor. The power-facto power-factorr rating for the generator generator should be determined determined after giving consideration to the load and the characteristics of the system that that will will be suppli supplied ed by the the gene genera rato tor. r. The The effe effect ct of power factor rating on machine capability is illustrated in Figure 3-1. (2) The power factor factor at which which a genera generator tor operate operatess is affected by the transmission system to which it is connected. nected. Transmiss Transmission ion systems systems are designed designed to have resisresistive character characteristi istics cs at their rated transmis transmission sion capacitie capacities. s. Conseq Consequen uently tly,, a genera generator tor connec connected ted to a transm transmiss ission ion system will typically operate at or near unity power factor during during maximum maximum output output periods. periods. During During lightly lightly loaded loaded
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EM 1110-2-3006 30 Jun 94
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EM 1110-2-3006 30 Jun 94 condit condition ions, s, howeve however, r, the genera generator tor may be requir required ed to assist assist in transmissi transmission on line voltage regulation. regulation. A generator operat operating ing on an HV transm transmiss ission ion system system with with relati relativel vely y short transmission transmission distances distances will typically typically be required required to supply reactive power (i.e., operate with a lagging power factor factor in an overex overexcit cited ed condit condition ion), ), due to the induct inductive ive character characteristi isticc of the unloaded unloaded transmission transmission line. A generator operated on a long, uncompensated EHV transmission line line will will typica typically lly be requir required ed to absorb absorb reacti reactive ve power power (i.e., (i.e., operat operatee with with a leadin leading g power power factor factor in an underunderexcited excited condition) condition),, due to the capacitiv capacitivee characteri characteristic stic of the the unlo unload aded ed tran transm smis issi sion on line line.. In the the latt latter er case case,, the the genera generator tor field field curren currentt requir requireme ements nts are substa substanti ntiall ally y below below rated rated field field curren currents, ts, thus thus reduci reducing ng the genera generator tor field field strength. strength. With reduced reduced field strength, strength, the generator generator operates closer to its stability limit (see Figure 3-1), making it more more suscep susceptib tible le to loss loss of synchr synchroni onism sm or pole pole slipping in the event of a system disturbance. (3) (3) It is high highly ly desi desira rabl blee that that the the gene genera rato torr be designed for the power factor at which it will operate in orde orderr to impr improv ovee syst system em stab stabil ilit ity. y. In gene genera ral, l, unle unless ss stud studie iess indi indica cate te othe otherw rwis ise, e, the the powe powerr fact factor or sele select cted ed should should be 0.95 0.95 for medium medium and large large genera generator torss unless unless they they will will be at the the end end of a long long tran transm smis issi sion on line line,, in which case a value approaching unity may be desirable.
(3) Typica Typicall values values of transi transient ent reacta reactance ncess for large large water water wheel wheel genera generator torss indica indicated ted by Figure Figure 3-2 are in accordance accordance with industry industry standard standard practice. practice. Guarantee Guaranteed d valu values es of tran transi sien entt reac reacta tanc nces es will will be appr approx oxim imat atel ely y 10 percent higher. (4) Average Average values of standard standard reactance reactance will probably be sufficiently close to actual values to determine the rating of high-voltage circuit breakers, and should be used in preliminary preliminary calculat calculations ions for other equipment. equipment. As soon as design calculati calculations ons for the specific machine machine are available, the design values should be used in rechecking the computations for other items of plant equipment. i. Amortisseur Amortisseur windings windings.
(1) Amortisse Amortisseur ur windings windings (also referred referred to as damper windings in IEEE 399; Dawes 1947; Fitzgerald and Kingsley sley 1961; 1961; and Puchst Puchstein ein,, Lloyd, Lloyd, and Conrad Conrad 1954) 1954) are essentiall essentially y a short-cir short-circuite cuited d grid of copper copper conductor conductorss in the the face face of each each of the the sali salien entt pole poless on a wate waterw rwhe heel el genera generator tor.. Two types types of amortiss amortisseur eur winding windingss may be specif specified ied.. In one, the pole face windings windings are not interinterconnec connected ted with with each each other, other, except except throug through h contac contactt with with the rotor metal. metal. In the second, second, the pole face windings windings are intentionally connected at the top and bottom to the adjacent damper windings.
h. Reactan Reactances ces.
(1) The eight eight differ different ent reacta reactance ncess of a salien salient-p t-pole ole generator are of interest in machine design, machine testing, ing, and in system system stabil stability ity and system system stabil stability ity model model studie studies. s. A full full discus discussio sion n of these reactan reactances ces is beyond beyond the scope of this this chapte chapter, r, but can be found found in electr electrica icall engineeri engineering ng texts (Dawes 1947; Fitzgerald Fitzgerald and Kingsley Kingsley 1961; 1961; Puchst Puchstein ein,, Lloyd, Lloyd, and Conrad Conrad 1954), 1954), and system system stability texts and standards (IEEE 399). (2) (2) Bot Both rat rated volt voltag agee valu valuees of tran ransie sient and and subtransient reactances are used in computations for determining mining momentary momentary rating and the interrupt interrupting ing ratings of circ circui uitt brea breake kers rs.. A low low net net thro throug ugh h reac reacta tanc ncee of the the generator generator and step-up step-up transform transformer er combined combined is desirable desirable for system system stability. stability. Where nominal nominal generator generator and transtransformer former design design reacta reactance ncess do not meet meet system system needs, needs, the increa increase se in cost cost of reduci reducing ng either either or both both the generato generatorr and transf transform ormer er reacta reactance ncess and the select selection ion of specia speciall gene genera rato torr reac reacta tanc ncee shou should ld be a subj subjec ectt for for econ econom omic ic stud study. y. Such Such a stud study y must must incl includ udee a cons consid ider erat atio ion n of spac spacee and and equi equipm pmen entt hand handli ling ng requ requir irem emen ents ts,, sinc sincee a redu reduct ctio ion n in reac reacta tanc ncee may may be acco accomp mpli lish shed ed by an increase in generator height or diameter, or both.
(2) The amortisseur amortisseur winding winding is of major importance importance to the stable operati operation on of the generator. generator. While While the generator ator is operat operating ing in exact exact synchr synchroni onism sm with with the power system system,, rotati rotating ng field field and rotor rotor speed speed exactl exactly y matche matched, d, there there is no curren currentt in the damper damper windin winding g and it essenessentially tially has no effect on the generator generator operation. operation. If there is a smal smalll dist distur urba banc ncee in the the powe powerr syst system em,, and and the the frequency tends to change slightly, the rotor speed and the rotati rotating ng field field speed speed will will be slight slightly ly differ different ent.. The rotor mass is perturbed when synchronizing power tends to pull the rotor rotor back into synchro synchronis nism m with the system system.. That That perturbat perturbation ion tends to cause the rotor-sha rotor-shaft-t ft-turbin urbinee runner runner mass to oscillate about its average position as a torsional pendulum. pendulum. The result result is relatively relatively large pulsation pulsationss in the energy energy component component of the generator generator current. current. In worst case, the oscillations can build instead of diminishing, resulting in the generator pulling out of step with possible consequential damage. (3) (3) At the the onse onsett of the the osci oscill llat atio ions ns,, howe howeve ver, r, the the amor amorti tiss sseu eurr wind windin ing g begi begins ns to have have its its effe effect ct.. As the the rotati rotating ng field field moves moves in relati relation on to the rotor, rotor, curren currentt is induce induced d in the amortis amortisseu seurr windin windings. gs. Induct Induction ion motor
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EM 1110-2-3006 30 Jun 94 action action results, results, and the rotor is pulled pulled back toward toward synchronism by the amortisseur winding action. (4) The amorti amortisse sseur ur (dampe (damper) r) windin winding g is of impor impor-tance tance in all power system systems, s, but even more more import important ant to system systemss that that tend tend toward toward instab instabili ility, ty, i.e., i.e., system systemss with with large large loads distant from generation generation resources, resources, and large intertie loads. (5) In all cases, cases, connec connected ted amorti amortisse sseur ur windin windings gs are recommende recommended. d. If the windings are not interconnect interconnected, ed, the curren currentt path path betwee between n adjace adjacent nt windin windings gs is throug through h the fiel field d pole pole and the rotor rotor rim. rim. This This tends tends to be a high high impe impeda danc ncee path path,, and and redu reduce cess the the effe effect ctiv iven enes esss of the the wind windin ing, g, as well well as resu result ltin ing g in heat heatin ing g in the the curr curren entt path. Lack of interconnec interconnection tion leads leads to uneven heating of the damper damper windings, windings, their their deteriora deterioration, tion, and ultimatel ultimately y damage to the damper bars. (6) The amorti amortisse sseur ur windin winding g also also indire indirectl ctly y aids aids in reducing reducing generator generator voltage swings under some fault conditions. tions. It does this by contri contribut buting ing to the reducti reduction on of the ratio of the quadrature reactance and the direct axis reactance, tance, Xq"/Xd". This This rati ratio o can can be as great great as 2.5 for for a salient salient pole generator generator with no amortisseu amortisseurr winding, winding, and can be as low as 1.1 if the salient pole generator has a fully interconnected winding. j. Efficiencies. The value value of effic efficien iency cy to be used in
preparing the generator specification should be as high as can be economically justified and consistent with a value manufa manufactu cturer rerss will will guaran guarantee tee in their their bids. Speed Speed and power power factor factor rating ratingss of a genera generator tor affect affect the effici efficienc ency y slightly, slightly, but the selection selection of these characterist characteristics ics is governe erned d by othe otherr cons consid ider erat atio ions ns.. For For a gene genera rato torr of any any given speed and power factor rating, design efficienc efficiencies ies are reduced by the following:
on the generators generators and connected equipment equipment under phaseto-ground to-ground fault conditions conditions,, and to permit permit the application application of suitable ground ground fault relaying. relaying. Suitable Suitable neutral groundgrounding equipm equipment ent should should be provid provided ed for each each genera generator tor in hydroelect hydroelectric ric power plants. The generator generator neutrals should should be provid provided ed with with curren current-l t-limi imitin ting g device devicess in the neutra neutrall circui circuits ts to limit limit the windin winding g fault fault curren currents ts and result resulting ing mechanical mechanical stresses stresses in the generators generators in accordance accordance with IEEE IEEE C62. C62.92 92.2 .2 requ requir irem emen ents ts.. Also Also,, gene genera rato torr circ circui uitt brea breake kers rs are are desi design gned ed for for use use on high high impe impeda danc ncee grounded systems, where the phase-to-ground short-circuit current current will not exceed exceed 50A. High impedance impedance groundin grounding g with distributi distribution on transform transformers ers and secondary secondary resistors resistors is the method of choice for waterwheel generators. b. Choic Choicee of grou ground ndin ing g meth method od .
The cho choice of generator neutral grounding type for each installation, and the selection of the most suitable type and rating of neutral grounding grounding equipment, equipment, should be made after preparapreparation of fault current calculations and consideration of the following factors: (1) Limitati Limitation on of winding winding fault current and resulting resulting mechanical stresses in the generator. (2) (2) Limit Limitat atio ion n of tran transi sien entt over overvo volt ltag ages es due due to switching operations and arcing grounds. (3) Limitati Limitation on of dynamic overvoltage overvoltagess to ground ground on the unfaulted phases. (4) Generator Generator surge protectio protection n (see paragraph paragraph 3-4). (5) (5) Gene Genera rato torr grou ground nd faul faultt graph 8-6b(3)).
rela relayi ying ng (see (see para para--
(6) Limitati Limitation on of damage damage at the fault. fault.
(1) Higher Higher Short-Circuit Short-Circuit Ratio (see paragraph paragraph 3-2 e).
(7) Neutral Neutral switchgear switchgear requiremen requirements. ts.
(2) Higher Higher Wk 2 (see paragraph 3-5 b).
(8) Cost of neutral neutral grounding grounding equipment equipment..
(3) Above-Norma Above-Normall Thrust. Thrust. Calculate Calculated d efficienci efficiencies es should should be obtained obtained from the supplier as soon as design data for the generators are available. able. These These design design effici efficienc encies ies should should be used used until until test values are obtained.
c. Solid Solid neutra neutrall ground grounding ing. Solid Solid neutral neutral groun groundin ding g is the the simp simple lest st grou ground ndin ing g meth method od,, sinc sincee tran transi sien entt overvoltages and overvoltages to ground on the unfaulted phases during phase-to-ground faults are held to a minimum. mum. Solid Solid neutral neutral groundin grounding g does does produc producee maximu maximum m ground ground fault fault curren currentt and possib possible le damage damage at the fault. fault. Solid neutral neutral grounding grounding is not recommend recommended. ed.
3-3. Generator Generator Neutral Neutral Grounding Grounding Rea Reactor neu neutral grounding grounding has certain certain desirable desirable character characteristic isticss similar similar to those of solid solid neutral grounding grounding.. It is a preferred preferred method method d. Reac Reactor tor neut neutra rall
a. Genera Generall. The main reasons reasons for for grounding grounding the neuneu-
trals trals of synchronou synchronouss generators generators are to limit limit overvolta overvoltages ges
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grou ground ndin ing g.
EM 1110-2-3006 30 Jun 94 of ground grounding ing in cases cases where where a neutra neutrall curren current-l t-lim imiti iting ng devi device ce is requ requir ired ed to meet meet ANSI ANSI/I /IEEE EEE shor shortt-ci circ rcui uitt requir requireme ements nts and where where the ratio ratio of the zero sequen sequence ce reactance reactance to the positive positive sequence sequence subtransi subtransient ent reactance reactance at the fault does does not exceed 6.0. Reactor Reactor neutral neutral groundgrounding ing limi limits ts tran transi sien entt over overvo volt ltag ages es and and over overvo volt ltag ages es to ground on the unfaulted phases to safe values where the above reactance ratio does not exceed approximately 6.0. However, in most hydro applications, this reactance ratio approaches or exceeds 6.0, and since the high impedance distribution transformer-secondary resistor system is more economical, reactor neutral grounding does not find widespread spread use in hydro applications. applications. e. Resi Resist stor or neut neutra rall grou ground ndin ing g. Resistor neutral grounding can be considered in cases where solid neutral grou ground ndin ing g or reac reacto torr neut neutra rall grou ground ndin ing g woul would d not not be satisfact satisfactory; ory; where several several generator generatorss are paralleled paralleled on a common bus, especially in the case of generators of small or medium medium kVA rating rating;; and where there there are no expose exposed d overhead overhead feeders feeders supplied at generator generator voltage. voltage. The resistor is usually usually rated rated to limit limit the generator generator neutral neutral current current during a phase-to-ground fault to a value between 100 and 150 percent percent of the generato generatorr full-l full-load oad current. current. Possib Possible le damage at the fault is thus materially reduced, yet sufficient ground fault current is available to permit the application cation of satisfact satisfactory ory and selective selective ground fault fault relaying. relaying. The The tech techni niqu quee does does prod produc ucee high high volt voltag agee to grou ground nd,, exposi exposing ng insula insulatio tion n system systemss of equipm equipment ent connec connected ted to the generator to the possibility of insulation failure. f. Distribution transformer-secondary resistor neutral grounding.
(1) This This is the preferre preferred d method method of genera generator tor neutral neutral grounding and is, in effect, high-resistance neutral grounding. ing. This This is the the meth method od used in most most North North Amer Americ ican an hydro installations because the cost of grounding devices and neutra neutrall switch switchgea gearr for other other ground grounding ing method methodss is excessive due to the large values of ground fault current. It is also also applic applicabl ablee to genera generator torss connec connected ted direct directly ly to delta-conn delta-connected ected windings windings of step-up step-up power transform transformers, ers, especially where there are no overhead feeders supplied at genera generator tor voltage. voltage. The characte characteris ristic ticss of this this method method of grou ground ndin ing, g, with with resp respec ectt to tran transi sien entt over overvo volt ltag ages es to ground ground on the unfaul unfaulted ted phases phases and the requir requireme ement nt for the use of ungrou ungrounde nded-n d-neut eutral ral rated rated surge surge arrest arresters ers for generator surge protection, are similar to those of resistor neutral grounding. (2) (2) With With this this meth method od of grou ground ndin ing, g, the the gene genera rato torr neutral current, during a phase-to-ground fault, is limited to a very low value, usually between 5A and 15A, by the
use of a relati relativel vely y low-oh low-ohm m resist resistor or shunte shunted d across across the secondary of a conventional step-down transformer whose primary primary is connected connected in the generator generator neutral neutral circuit. The possible damage at the fault is therefore least of any of the the vari variou ouss grou ground ndin ing g meth method ods. s. Howe Howeve ver, r, the the type type of generator ground fault relaying which can be applied has certai certain n disadv disadvant antage agess when when compar compared ed to the relayi relaying ng which can be used with with other grounding grounding methods. methods. Due to relativel relatively y low relay relay sensitivit sensitivity, y, a considera considerable ble portion portion of the genera generator tor windin windings gs near near the neutra neutrall ends ends cannot cannot be protected against ground faults, the relaying is not selective, and the relay sensitivity for ground faults external to the generator generator varies varies greatly greatly with the fault resistanc resistancee and the resistance of the return circuit for ground fault current. The kVA rating rating of the ground grounding ing transf transform ormer er should should be based on the capacitive current which would flow during a phas phasee-to to-g -gro roun und d faul faultt with with the the gene genera rato torr neut neutra rall ungrounded. (3) Due to the relativ relativee infreq infrequen uence ce and short duraduration of ground faults, a rating of 25 to 100 kVA is usually adequa adequate te for the transfo transforme rmer. r. The voltage voltage rating rating of the transformer high-voltage winding should be equal to rated generator generator voltage, voltage, and the transform transformer er low-voltag low-voltagee winding should should be rated rated 240 V. The rating rating of the secondar secondary y resistor is based on making the resistor kW loss at least equal to the capacitive fault kVA. g. Generator Generator neutral neutral equipmen equipment t .
(1) An automa automati ticc air circuit circuit breaker breaker should should be proprovided in the neutral circuit of each generator whose neutral tral is solidl solidly y ground grounded, ed, reacto reactorr ground grounded, ed, or resist resistor or ground grounded. ed. The circuit circuit breaker breaker should should be a metalmetal-cla clad, d, drawout type, either 1-pole or 3-pole, with a voltage rating ing at leas leastt equa equall to rate rated d gene genera rato torr volt voltag age, e, and and with with adequate adequate ampere ampere interrupti interrupting ng capacity, capacity, at rated rated voltage, voltage, for the maximu maximum m moment momentary ary neutra neutrall curren currentt during during a single single phase-to phase-to-gr -groun ound d fault. fault. For genera generator tor neutra neutrall serservice, the circuit breakers may be applied for interrupting duties duties up to 115 percen percentt of their their namepl nameplate ate interr interrupt upting ing ratings. ratings. When 3-pole 3-pole breakers breakers are used, used, all poles should should be paralleled on both line and load sides of the breaker. (2) (2) A sing single le-p -pol olee airair-br brea eak k disc discon onne nect ct shou should ld be provided provided in each generator neutral circuit using distribudistribution transforme transformer-sec r-secondar ondary y resistor resistor type grounding. grounding. The discon disconnec nectt should should have have a voltag voltagee rating rating equal equal to rated rated generator voltage, and should have the minimum available momen omenttary ary and cont contin inu uous ous cur current rent rati rating ngs. s. The The disconnec disconnect, t, distribut distribution ion transform transformer, er, and secondary secondary resisresistor should be installed together in a suitable metal enclosure. sure. The distrib distributi ution on transfor transformer mer should should be of the dry
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EM 1110-2-3006 30 Jun 94 type, and its specifications should require a type of insulation that does not require a heater to keep moisture out of the transformer.
3-4. Generator Generator Surge Surge Protection Protection a. Surge Surge protec protection tion equipm equipment ent .
Sinc Sincee hydroe hydroele lect ctri ricc generators are air-cooled and physically large, it is neither prac practi tica call nor nor econ econom omic ical al to insu insula late te them them for for as high high impulse impulse withstand withstand level as oil-insul oil-insulated ated apparatus of the same same voltag voltagee class. class. Becaus Becausee of this and the relati relative ve cost of procuring and replacing (or repairing) the stator winding, ing, suitab suitable le surge surge protec protectio tion n equipm equipment ent should should be proprovide vided d for for each each gene genera rato tor. r. The The equi equipm pmen entt cons consis ists ts of specia speciall surge surge arrest arresters ers for protec protectio tion n agains againstt transi transient ent overvolta overvoltage ge and lightning lightning surges, surges, and special special capacitors capacitors for limiting the rate of rise of surge voltages in addition to limiting their magnitude. b. Insula Insulation tion impulse impulse level. The The impul impulse se level level of the
stator winding insulation of new generators is approximately equal to the crest value of the factory lowfreque frequency ncy withst withstand and test test voltag voltage, e, or about about 40.5 40.5 kV for 13.8-kV generat generators. ors. The impulse impulse breakdown breakdown voltages voltages for surg surgee arre arrest ster erss for for 13.8 13.8-- kV genera generator tor protec protectio tion n are approxima approximately tely 35 kV for for 1212-kV grounded-neut grounded-neutral ral rated rated arresters, and approximately 44 kV for for 15 kV ungrounded ungroundedneutra neutrall rated rated arrest arresters ers.. Ground Groundeded-neu neutra trall rated rated surge surge arresters arresters therefore therefore provide provide better better protection protection to generators generators than ungrounded-neutral rated arresters. c. Ground Groundeded-neu neutra trall rated rated arrest arresters ers.
To corr orrect ectly apply grounded-neutr grounded-neutral al rated rated arresters arresters without an unacceptab ceptable le risk risk of arrest arrester er failur failure, e, the powerpower-fre freque quency ncy voltage voltage applied applied across across the arrester under normal or fault condit condition ionss must must not exceed exceed the arrest arrester er voltag voltagee rating rating.. This This requ requir irem emen entt is usua usuall lly y met met if the the rati ratio o of zero zero sequence reactance to positive sequence subtransient reactance at the fault, for a single phase-to-ground fault, does not exceed exceed approx approxima imatel tely y 6.0. 6.0. Since Since distri distribut bution ion transtransformer former-se -secon condar dary y resist resistor or ground grounding ing does does not meet meet this this requirement, only ungrounded-neutral rated surge arresters should should be applied applied for generator generator surge protectio protection. n. d. Arrester Arrester arrangement arrangement .
In most most case cases, s, one one surge surge arrester and one 0.25-microfarad surge capacitor are connect nected ed in para parall llel el betw betwee een n each each phas phasee and and grou ground nd.. In certai certain n cases, cases, howeve however, r, such such as the condit condition ion where where the generators supply distribution feeders on overhead lines at genera generator tor voltag voltage, e, or where where two or more more genera generator torss will will be oper operat ated ed in para parall llel el with with only only one one of the the gene genera rato torr
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neutrals grounded, two of the above capacitors per phase should should be provided provided.. A separa separate te set of surge surge protect protection ion equipm equipment ent should should be provid provided ed for each each genera generator tor.. The equipment should be installed in metal enclosures located as close to the generator terminals as possible.
3-5. Mechanical Mechanical Characteris Characteristics tics The section section of Guide Specificatio Specification n CW-16120 CW-16120 covering covering mechanica mechanicall character characteristi istics cs of the generator generator provides for the inclusion inclusion of pertinent pertinent data on the turbine. turbine. Since generator erator manufactu manufacturers rers cannot prepare prepare a complete complete proposal proposal without without turbine turbine character characteristi istics, cs, the generator generator specifica specification tion is not advertis advertised ed until until data data from from the turbin turbinee contra contract ct are available. a. Spee Speeds ds.
(1) Hydrau Hydraulic lic require requiremen ments ts fix the speed speed of the unit unit within within rather rather narrow narrow limits limits.. In some speed ranges, ranges, however ever,, ther theree may may be more more than than one one sync synchr hron onou ouss spee speed d suitable for the turbine, but not for the generator because of design limitations. (2) Generators Generators below 360 360 r/min and 50,000 kVA and smaller are nominally designed for 100 percent overspeed. Generators above 360 r/min and smaller than 50,000 kVA are generally generally designed designed for 80 percent percent overspeed. overspeed. GeneraGenerators tors larg larger er than than 50,0 50,000 00 kVA, rega regard rdle less ss of spee speed, d, are are design designed ed for 85 perc percent ent overspe overspeed. ed. Becaus Becausee of the high high overspeed overspeed of adjustabl adjustablee blade (Kaplan) turbines, turbines, in some cases more than 300 percent of normal, it may be impracticable to design and build a generator to nominal design limitati limitations. ons. Where overspeed overspeedss above nominal values values are indicated by the turbine manufacturer, a careful evaluation of the operatin operating g condit condition ionss should should be made. made. Also, Also, the designer should be aware that turbine and generator overspeed requirements are related to the hydraulic characteristi istics cs of the the unit unit wate waterr inle inlett stru struct ctur ures es.. Hydr Hydrau auli licc transients that might result from load rejections or sudden load changes need to be considered. (3) (3) Gene Genera rato tors rs for for proj projec ects ts with with Kapl Kaplan an turb turbin ines es have been designed for runaway speeds of 87-1/2 percent of the theoretical theoretical maximum maximum turbine speed. speed. In accordance accordance with requirements of Guide Specification CW-16120, the stresses during design runaway speeds should not exceed two-thirds two-thirds of the yield yield point. However, However, where the design overspeed overspeed is less than the theoretical theoretical maximum runaway speed, speed, calcul calculate ated d stress stresses es for the theore theoretic tical al maximu maximum m speed should be less than the yield points of the materials.
EM 1110-2-3006 30 Jun 94 b. Flywhe Flywheel el effec effect t .
(1) (1) The The flyw flywhe heel el effe effect ct ( Wk ²) of a machine is expressed as the weight of the rotating parts multiplied by the the squa square re of the radius radius of gyra gyrati tion on.. The The Wk ² of the generator can be increased by adding weight in the rim of the rotor rotor or by increa increasin sing g the rotor rotor diamet diameter. er. Increa Increasin sing g the Wk ² increases the generator cost, size, and weight, and lowers lowers the efficie efficiency ncy.. The need for above-no above-norma rmall Wk ² should should be analyz analyzed ed from from two standp standpoin oints, ts, the effect effect on power system stability, and the effect on speed regulation of the unit. (2) Electrica Electricall system system stabilit stability y considerat considerations ions may in special cases require a high Wk ² for speed speed regulat regulation ion.. As Wk ² is only only one of severa severall adjust adjustabl ablee factor factorss affect affecting ing system stability, all factors in the system design should be considere considered d in arriving arriving at the minimum overall overall cost. SuffiSufficient Wk ² must be provided to prevent hunting and afford stabil stability ity in operat operation ion under under sudden sudden load changes changes.. The index of the relative stability of generators used in electrical system calculations is the inertia constant, H , which is expressed in terms of stored energy per kVA of capacity. It is computed as: s = 0.231 (Wk ²) ²) (r/min)² x 10-6 kVA kVA
H = kW
(3) (3) The The iner inerti tiaa cons consta tant nt will will range range from from 2 to 4 for for slow-s slow-spee peed d (under (under 200 r/min) water water wheel wheel genera generator tors. s. Transient hydraulic studies of system requirements furnish the best information concerning the optimum inertia constant, but if data from studies are not available, the necessary Wk ² can be computed or may be estimated from a knowledge of the behavior of other units on the system. Estimates of the effect of increased Wk ² on the generator base cost are indicated by Figure 3-3. (4) The amoun amountt of Wk ² required for speed regulation is affected by hydraulic hydraulic conditions conditions (head, length of penstock, allowable pressure rise at surge tank, etc.) and the rate rate of gove govern rnor or acti action on.. The The spee speed d incr increa ease se when when full full load load is sudd sudden enly ly drop droppe ped d shou should ld be limi limite ted d to 30 to 40 percen percentt of normal normal speed. speed. This This allowa allowable ble limit limit may sometimes be increased to 50 percent if the economics of the additio additional nal equipme equipment nt costs are prohibit prohibitive ive.. When When stat statio ion n powe powerr is supp suppli lied ed from from a main main gene genera rato tor, r, the the effect of this speed rise on motor-driven station auxiliaries should should be consid considere ered. d. Smalle Smallerr genera generator torss servic servicing ing isoisolated load blocks blocks should should have sufficient sufficient Wk ² to provid providee satisfact satisfactory ory speed regulation. regulation. The starting starting of large motors on such such syst system emss shou should ld not not caus causee a larg largee drop drop in the the isolated system frequency.
Figure Figure 3-3. Effect of increas increased ed Wk 2 on generator cost (included by permission of Westinghouse Electric Corp)
(5) (5) The The meas measur uree of stab stabil ilit ity y used used in turb turbin inee and and governor governor calculations calculations is called called the flywheel flywheel constant constant and is derived as follows: Flywheel Constant = (Wk ²) ²) (r/min)² hp
If the horsepower ( hp) in this formula is the value corresponding to the kVA (at unity power factor) in the formula for the inertia constant ( H ), ), the flywheel constant will be numerically equal to 3.23 x 10 6 multiplied by the inertia constant. constant. As the actual turbine turbine rating seldom seldom matches matches the genera generator tor rating rating in this this manner manner,, the flywhe flywheel el consta constant nt should be computed with the above formula. c. Cool Coolin ing g.
(1) (1) Loss Losses es in a gene genera rato torr appe appear ar as heat heat whic which h is dissipate dissipated d through radiation radiation and ventilation. ventilation. The generator rotor is normal normally ly constr construct ucted ed to functi function on as an axial axial flow blower, or is equipped with fan blades, to circulate air through through the windings. windings. SmallSmall- and moderate-siz moderate-sizee generators may be partially enclosed, and heated generator air is disc discha harg rged ed into into the the gene genera rato torr hall hall,, or duct ducted ed to the the outsid outside. e. Larger Larger machine machiness are enclose enclosed d in an air housing housing with air/water heat exchangers to remove heat losses. (2) Open cooling cooling systems are normally normally adequate for small- and medium-size generators (less than 10 MW ). If special ventilating and air cleaning equipment is required to accommodate an open cooling system, the cost of these features should be compared against the cost of having a generator generator with a closed closed air recirculatin recirculating g system system with air/ water heat exchangers. (3) An enclos enclosed ed air housing housing with a recirc recircula ulated ted air cooling system with air/water heat exchangers is preferred for units of 10 MW and larger larger.. Coolin Cooling g of the genera generator tor
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EM 1110-2-3006 30 Jun 94 can be more easily controlled with such a system, and the stat stator or wind windin ings gs and and vent ventil ilat atin ing g slot slotss in the the core core kept kept cleane cleaner, r, reduci reducing ng the rate rate of deteri deteriora oratio tion n of the stator stator windin winding g insula insulatio tion n system system.. The closed closed system system also permits mits the additi addition on of automa automatic tic fire fire protec protectio tion n system systems, s, attenu attenuate atess genera generator tor noise, noise, and reduce reducess heat heat gains gains that that must must be acco accomm mmod odat ated ed by the the powe powerh rhou ouse se HVAC HVAC system. (4) WaterWater-coo cooled led heat heat exchan exchanger gerss used used in a recirc recircuulated lated air cooling system consist of groups groups of thin-wall thin-walled ed finned finned tubes tubes with with approp appropria riate te water water boxes, boxes, valves valves,, and headers. headers. Standard Standard air coolers coolers are designed designed for 50-poundper-sq per-squar uare-i e-inch nch (psi) (psi) workin working g pressu pressure, re, but can be supsupplied plied for 100-ps 100-psii workin working g pressu pressure re for a slight slightly ly higher higher price. price. The 100-psi 100-psi rated rated coolers coolers should should be used where the hydraulic head of the cooling water source is greater than than 100 ft. For best servic service, e, tube sheets sheets of 90/10 Cu/Ni Cu/Ni should should be used for air and bearing bearing lube lube oil cooler coolers. s. The turbine spiral case is normally used as the cooling water sour source ce for projec projects ts with with head headss of up to 250 ft. Wh Wher eree project project head exceeds exceeds approxima approximately tely 250 ft, pumped pumped systems using a tailwater source are preferred. (5) The design pressure pressure for the stator stator heat exchangers exchangers shou should ld be base based d on pump pump shut shut-o -off ff head head if a pump pumped ed sour source ce of cool coolin ing g wate waterr is used used.. Desi Design gn pres pressu sure re for spir spiral al case case cool coolin ing g wate waterr sour source cess shou should ld be base based d on maxi maximu mum m proj projec ectt pool pool leve level, l, plus plus a surg surgee allo allowa wanc nce. e. Heat exchanger exchanger hydrostati hydrostaticc tests tests should should be performed performed at pressu pressures res of 150 perce percent nt of rated rated pressu pressure. re. Design Design cooling water temperatur temperaturee should should be the maximum temperatemperature ture of the the cool coolin ing g wate waterr sour source ce,, plus plus a cont contin inge genc ncy y allowance. (6) The water supply supply line to the air air coolers coolers should be separate separate from the water line to the thrust-beari thrust-bearing ng cooler. cooler. It may prove desirable to modulate the water flow to the air coolers to control the generator temperature, or to shut it off entirely entirely when the unit is being stopped stopped.. It is desirdesirable to keep a full flow of water through the thrust bearing oil cooler cooler whenever whenever the unit is turning. turning. Each cooling cooling water supply line should be equipped with a flow indicator. The flow indicator indicator should should be equipped with with an alarm contact for low flow. (7) (7) Each Each air air cool cooler er shou should ld be equi equipp pped ed with with wate waterr shut-off valves so a cooler can be cut out if in trouble, or be serv servic iced ed whil whilee the the gene genera rato torr is oper operat atin ing. g. Cool Cooler erss shou should ld be desi design gned ed with with as grea greatt a numb number er of heat heat exchan exchanger ger tubes in the air flow flow passag passagee as practi practical cal in order to reduce reduce water usage. usage. Adequate Adequate floor drains drains inside inside the air housing should be provided to remove any water
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that that may conden condense se on or leak from from the cooler coolers. s. The unit drain header should empty into the tailwater if plant condition ditionss permit permit,, but the drain drain should should not be termin terminate ated d where where it will will be subjec subjectt to negati negative ve pressu pressures res from the draft draft tube, tube, since since this this will will impose impose negati negative ve pressu pressures res on the heat exchangers. (8) Heated Heated air from the generato generatorr enclos enclosure ure should should not be used for plant space heating because of the possibility bility of exposu exposure re of plant plant person personnel nel to ozone, ozone, and the possibility of CO 2 being being discharged discharged into the plant. plant. Water from the coolers may be used as a heat source in a heat pump pump type type of heatin heating g system system,, but if water water flow flow modula modula-tion is used, there may not be enough heat available during ing peri period odss of ligh lightt load loadin ing, g, or when when the the plan plantt is shut shut down. d. Weights and dimensio dimensions ns.
(1) Estimatin Estimating g weights and dimensions dimensions of the generators should be obtained from generator manufacturers for plant design design purposes. purposes. These figures figures should be rechecked rechecked after after bid data data are availa available ble on the partic particula ularr genera generator tor selected. selected. The contempla contemplated ted speed, speed, Wk ², ², short-circuit ratio, reactance, and over-speed are the usual factors that have the the grea greate test st effe effect ct on weig weight ht vari variat atio ion. n. Wh Wher eree a high high value Wk ² is required, a machine of the next larger frame size size with with cons conseq eque uent nt incr increa ease se in diam diamet eter er may may be required. (2) (2) Dime Dimens nsio ions ns of the the roto rotorr and and the the meth method od of assembling the rotor and the shaft in the generator have an impor importan tantt bearin bearing g on crane clearan clearances ces.. The number number and location of air coolers and the shape of the air housing on a generator with the closed type of cooling system should be studied for their effect on the dimensions of the genera generator tor room. room. Genera Generator tor and turbin turbinee access access should should be consid considere ered, d, as well well as the possib possible le need need for suppre suppressi ssing ng noise radiated into the powerhouse.
3-6. Excitation Excitation Systems Systems a. Genera Generall. Curren Currentt practice practice in the design design of Corps of Engine Engineers ers power plants plants is to use solid state bus-fed bus-fed excita excitatio tion n system systemss for the genera generator tor excite exciterr and voltag voltagee regula regulator tor function function.. Solid Solid state state excita excitatio tion n system systemss curcurrently rently availa available ble from from reputa reputable ble manufa manufactu cturer rerss exhibi exhibitt reliabilit reliability y comparabl comparablee to, and in some cases better than, older older mechan mechanica icall system systems. s. Excita Excitatio tion n system system specif specifica ica-tion tionss shou should ld be care carefu full lly y prep prepar ared ed,, with with atte attent ntio ion n to requirements of the power system to which the generator will be connected. connected.
EM 1110-2-3006 30 Jun 94 b. Large Large gener generato ators rs.
(1) The stability stability of a large turbineturbine-gener generator ator set while connec connected ted to its power power system system is critic criticall ally y import important ant.. However, the designer must also consider the unit’s characteristics when operating alone, or in an isolated “island” much smaller than the normal power system. (2) One exampl examplee of a unit unit operatin operating g alone alone is a main unit unit servin serving g as the station station service service source source in a plant plant that that become becomess separa separated ted from from its power power distri distribut bution ion system system.. The The unit unit will will have have to acce accept pt moto motorr star starti ting ng load loads, s, and and othe otherr stat statio ion n serv servic icee dema demand ndss such such as gate gate and and valv valvee operat operation ion,, while while mainta maintaini ining ng a safe safe and stable stable output output volt voltag agee and and freq freque uenc ncy. y. All All this this will will be acco accomp mpli lish shed ed while operating at a fraction of its rated output. (3) When When operat operating ing in an “island, “island,”” the unit may be required to operate in parallel with other units while running at speed-no-load in order to provide enough capacity to pick up blocks of load without without tripping tripping off line. line. In this case, case, stable stable operat operation ion withou withoutt the stabil stabilizi izing ng effect effect of a very large system system is critical critically ly important important to restoring restoring service, and putting the system back together. c. Smal Smalll units units. For small small units units producin producing g energy energy for
a very large system, stability is not so critical since system voltage support will be beyond the small unit’s capabili bility ty.. None Noneth thel eles ess, s, for for its its own own safe safe oper operat atio ion, n, good good voltage voltage control is important. important. An extremely extremely high response response system system is not necess necessary ary,, but the system system should should respon respond d rapidly enough to prevent dangerous voltage excursions. d. Excitation Excitation system system characteristi characteristics cs.
(1) In general, general, there are two types of static static excitation excitation systems: one using a full-inverting power bridge, and the othe otherr usin using g a semi semi-i -inv nver erti ting ng powe powerr brid bridge ge.. The The full full-invert inverting ing system system uses uses six (or more) more) silico silicon n contro controlle lled d rectif rectifier ierss (SCRs) (SCRs) in the power power bridge bridge so the genera generator tor field field voltag voltagee can be forced forced both both positi positive ve and negati negative. ve. The semi-i semi-inve nverti rting ng system system allows allows the genera generator tor field field voltage to be forced positive, and reduced to zero. (2) The full-inv full-invert erting ing bridge bridge allows allows boost boost and buck buck operat operation ion much much like like that that availa available ble in older older system systems, s, but with with the potenti potential al for a faster faster respons response. e. Faster Faster respons responsee mean meanss less less phas phasee shif shiftt in the the cont contro roll acti action on,, and and the the reduction of phase shift permits control action to increase the stability of volt oltage regulation (see also paragraph 3-6 g(6)).
(3) Dips Dips in output output voltag voltagee can be reduce reduced, d, and voltvoltage recovery speed improved, with the field forcing function tion.. Incr Increa easi sing ng the the fiel field d volt voltag agee help helpss grea greatl tly y in overcoming the lag caused by the inductance of the generator field, and increases the speed of response of generator output output voltage to control control action. action. However, However, the exciter ceilin ceiling g voltag voltagee (maxim (maximum um forcin forcing g voltag voltagee availa available ble)) to the generator field must be limited to a value that will not damage damage field insulation. insulation. The manufacturer manufacturer will determine determine the exciter ceiling voltage based on the nominal response specified. (4) The semi-invert semi-inverting ing system also provides provides for fast respon response, se, but withou withoutt the capabi capabilit lity y to force force the field field voltage voltage negative negative with respect respect to its normal polarity. polarity. This slows slows the genera generator tor output output voltag voltagee respon response se capabi capabilit lity. y. One One or more more diod diodes es prov provid idee a path path for for deca decayi ying ng fiel field d current when the AC contactor is opened. (5) Power system system requireme requirements nts and machine machine voltage performance during unit load rejections should be considered ered in evaluati evaluating ng the use of a semi-i semi-inve nverti rting ng system. system. If stabil stability ity requir requireme ements nts can be met and adequa adequate te voltag voltagee performan performance ce maintained maintained during unit load rejection rejections, s, then eith either er a semi semi-i -inv nver erti ting ng or a full full-i -inv nver erti ting ng syst system em is accept acceptabl able. e. If either either criterio criterion n appear appearss compro compromis mised, ed, a full-inverting system is recommended. (6) If the partic particula ularr genera generator tor (or plant) plant) in questi question on has sufficient capacity to affect the control area to which it is connected, a full-inverting voltage regulating system would be justified if the control area has a high ratio of energy import (or export) to load, and is marginally stable or experiences experiences tie line line separations. separations. A full-inverti full-inverting ng system can force voltage down if an export tie line is lost, and can force force genera generator tor voltage voltage down down if the machine machine is suddenly tripped off line while carrying a substantial load. Both cases will reduce voltage stresses on the generator; the the firs firstt exam exampl plee will will assi assist st in main mainta tain inin ing g syst system em stability, the second will help protect the generator winding from dangerous overvoltages. e. Excitation Excitation system system arrange arrangement ment .
(1) In general, bus-fed bus-fed solid solid state state excitatio excitation n systems systems are made up of three elements: elements: the power potential potential transtransform former er (PPT (PPT), ), the the powe powerr brid bridge ge (or (or rect rectif ifie ier) r),, and and the the control section (voltage regulator function). (2) Locati Location on of the PPT will depend depend on the supply supply source source chosen chosen.. If power power to the PPT is supplied supplied from from the
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EM 1110-2-3006 30 Jun 94 generator leads, the bus arrangement will be affected, and that must be considered in the initial design and layout of the the powe powerh rhou ouse se.. If the PPT is fed from the genera generato torr delta bus, its location must be selected so that it will be reas reason onab ably ly clos closee to the the powe powerr brid bridge ge equi equipm pmen ent. t. The The PPT PPT shou should ld be spec specif ifie ied d to be self self-c -coo oole led, d, and and the the designer should consider this in determining its location. (3) (3) For For eith either er powe powerr sour source ce to the the PPT, PPT, prot protec ecti tion on should should be provided provided by current-lim current-limiting iting fuses. fuses. The available able faul faultt curr curren entt at the the inpu inputt to the the PPT PPT will will be quit quitee large, so it will be necessary to limit it to prevent destructive releases releases of energy energy at the fault location. location. Current-l Current-limit imit-ing fuses fuses also also provid providee circui circuitt cleari clearing ng withou withoutt curren currentt surges that can cause voltage transients which are dangerous to the integrity integrity of the generator generator insulation insulation.. When the fusibl fusiblee elemen elementt melts, melts, the fuse fuse essent essential ially ly become becomess a resi resist stor or in seri series es with with the the faul fault. t. Volta Voltage ge and and curr curren entt acro across ss the the resi resist stor or are are thus thus in phas phase, e, and and the the circ circui uitt is cleare cleared d at the first zero zero crossi crossing, ng, withou withoutt danger danger of arc restrike (if the fuse works properly). (4) The excitati excitation on system system should should also also provid providee for a means means of discon disconnec nectin ting g power power from from the genera generator tor field. field. In genera general, l, this this requir requires es that that power power be interr interrupt upted ed at the bridge input, at the generator field input, or at both places, and that a means of dissipating energy stored in the field be provided. provided. Energy Energy dissipation dissipation is a major consider consideration ation,, becaus becausee withou withoutt it the field field induct inductanc ancee will will cause cause field field voltage voltage to rise sharply sharply when field current current is interrupt interrupted, ed, possibly possibly rupturing rupturing the field insulation insulation.. Several Several methods exist to perform the field removal function. (a) One method of field removal removal for a semi-inverti semi-inverting ng syst system em uses uses a cont contac acto torr in the the AC inpu inputt to the the powe powerr brid bridge ge.. For For fiel field d disc discha harg rge, e, a diod diodee (cal (calle led d a free free-whee wheeli ling ng diod diode) e) can can be used used to prov provid idee a path path for for the the field field current to dissipate dissipate field energy. energy. Another Another method is to provid providee a shorti shorting ng contac contactt in series series with a discha discharge rge resist resistor or across across the generat generator or field. field. When When the Device Device 41 AC breaker opens, the auxiliary Device 41 shorting contact closes. (b) A method method which which can be used with a full-i full-inve nverti rting ng bridge bridge uses a field field breaker and discharge discharge resistor. resistor. This is a stra straig ight htfo forw rwar ard d meth method od wher wheree the the powe powerr from from the the brid bridg ge to the the field ield is inte nterrup rrupte ted, d, and and the field ield is simultaneously short-circuited through a discharge resistor. (c) With With either either a semisemi- or full-i full-inve nverti rting ng bridge bridge,, it is possible to use a device 41 in the DC side of the bridge, with with a thyr hyrist istor elem elemen entt to cont ontrol rol fiel ield ener nergy dissip dissipati ation. on. The thyrist thyristor or device device is a threethree- (or more) more)
3-12
junction semiconductor with a fast OFF to ON switching time time that that is capa capabl blee of goin going g to the the cond conduc ucti ting ng stat statee within within a very very short short time time (about (about one quarte quarterr of a cycle) cycle) after the Device 41 opens. (d) With With either either a semisemi- or full-i full-inve nverti rting ng bridge bridge,, it is possible to use a device 41 in the AC (input) side of the bridge bridge,, with with a thyris thyristor tor elemen elementt to contro controll field field energy energy dissip dissipati ation. on. The thyrist thyristor or device device is a threethree- (or more) more) junction semiconductor with a fast OFF to ON switching time time that that is capa capabl blee of goin going g to the the cond conduc ucti ting ng stat statee within within a very very short short time time (about (about one quarte quarterr of a cycle) cycle) after the Device 41 opens. (5) Power Power bridge bridge equipm equipment ent should should be housed housed in a cubicle cubicle by itself, itself, for safety and reduction reduction of electromag electromag-netic netic noise, noise, and be locate located d near near or beside beside the excita excitatio tion n contro controll cubicl cubicle. e. Both Both cubicl cubicles es should should be designed designed for reduction of radiated electromagnetic interference (EMI). (6) The power power electr electroni onics cs equipm equipment ent in the excita excita-tion tion syst system em can can be eith either er fanfan-co cool oled ed or self self-c -coo oole led. d. Fan-co Fan-coole oled d excita excitatio tion n system systemss are usuall usually y smalle smallerr than than self-coole self-cooled d systems, systems, but require require extra extra equipment equipment for the lead-lag lead-lag fan controls. controls. Fan-coole Fan-cooled d excitation excitation systems may require additional maintenance resulting from such things as fans fans failin failing g to start, start, air flow flow switch switches es failin failing, g, fan air flow causing oil from the turbine pit to be deposited on filt filter ers, s, and and wornworn-ou outt fan fan moto motors rs caus causin ing g nois noisee to be appl applie ied d to the the regu regula lato torr cont contro roll syst system em.. Self Self-c -coo oole led d excitation systems may require larger cubicles and higherrate rated d equi equipm pmen entt to allow allow for for heat heat tran transf sfer er.. On larg largee genera generator tors, s, it may not be practi practical cal to use a self-c self-cool ooled ed system. system. On smaller smaller units units it may may be preferabl preferable. e. Each unit unit should be judged on its life cycle costs. (7) (7) If the cap capabil abiliity of con connect nectin ing g a uni unit to a de-e de-ene nerg rgiz ized ed tran transm smis issi sion on syst system em will will be nece necess ssar ary y (“black start” capability), there may be a requirement for operat operating ing the genera generator tor at around around 25 percen percentt of nomina nominall voltag voltagee to energi energize ze transf transform ormers ers and transm transmiss ission ion lines lines with withou outt high high inru inrush sh curr curren ents ts.. This This requ requir irem emen entt may may impose the need for an alternate power source to the PPT sinc sincee the the powe powerr brid bridge ge migh mightt not not oper operat atee reli reliab ably ly at reduce reduced d voltag voltagee levels levels.. If an altern alternate ate supply supply source source is needed, provide switching and protection, and ensure that the normal PPT source and the emergency source cannot be connected connected in parallel. parallel. The power transmissi transmission on authority should be consulted to determine the voltage necessary for charging lines and transformers to re-energize a power system. system. Requiring Requiring additional additional power sources sources not only adds costs to the project, but complexity to the system, which may may not not be justi justifi fied ed.. The The comp comple lexi xity ty of a syst system em is
EM 1110-2-3006 30 Jun 94 usually usually proportio proportional nal to its maintenance, maintenance, failure, failure, and misoperation rate. f.
Excitation system regulators.
(1) The voltag voltagee regula regulator tor functi function on of modern modern solid solid state state excita excitatio tion n equipm equipment ent is an integr integral al part part of the syssystem, and will use digital control elements with microprocessor cessor-ba -based sed control control.. This This type type of contro controll provid provides es far more flexibility in changing regulator characteristics than the the olde olderr mech mechan anic ical al elem elemen entt type type of cont contro rol. l. It also also provides more precise and predictable control action, and will require far less maintenance. (2) (2) The The volt voltag agee regu regula lato torr func functi tion on shou should ld prov provid idee automatic and manual control of generator output voltage, with “bumpless” transfer between modes, over a range of at least plus or minus 10 percent from nominal generator voltag voltage. e. The bumpless bumpless transfer transfer requirem requirement ent means that the regulator control modes must track each other so that when the control mode is switched the generator voltage (or reactive output) will not exhibit a step change of any magnitude. (3) Voltag Voltagee regula regulator tor contro controll to mainta maintain in genera generator tor power factor, or maintain a selected var loading may also be required required.. If the plant is to have have an automati automaticc contro controll system, provisions should be required for control inputs to the the regu regula lato tor, r, and and it may may be poss possib ible le to disp dispen ense se with with some of the regulator regulator control control features, features, particular particularly ly if the plant will not be manned. g. Excitation Excitation system system access accessories ories.
(1) An AC input input voltmet voltmeter, er, a DC output output (field (field voltvoltage) age) voltme voltmeter ter,, and a DC field field ammete ammeterr are access accessori ories es that should be considered essential for a quick check on system system operation. operation. Rectifier Rectifier failure failure detection detection should also be considered, particularly for units controlled remotely. (2) Remotely Remotely operated operated controls are also essential essential for unit unitss cont contro roll lled ed from from loca locati tion onss remo remote te from from the the unit unit switchboar switchboards. ds. Maximum Maximum and minimum minimum excitation excitation limiter limiter equi equipm pmen entt shou should ld also also be prov provid ided ed in all all case cases. s. This This equipm equipment ent is critic critical al to units units that that are direct direct connec connected ted with other units on a common bus. (3) Moment Momentary ary connect connection ion of a DC source source of proper proper polarity to the generator field (field flashing) should also be required. required. Field flashing flashing provides provides prompt prompt and reliable reliable buildup buildup of generator generator voltage without reliance reliance on residual residual magnetism magnetism.. Include Include protection protection against overlong overlong application of the flashing flashing source. source. The simplest simplest source source for field
flashi flashing ng voltage voltage is the station station battery battery.. If the unit is not requir required ed to have have black black start start capabi capabilit lity, y, an altern alternati ative ve to using using the station station battery battery is to use an AC power power source source with with a rectif rectifier ier to furnis furnish h the necessar necessary y DC power power for field field flashing. flashing. This alternative alternative source source could be considered considered if it is determ determine ined d to be signif significa icantl ntly y more more econom economica icall than than prov provid idin ing g addi additi tion onal al stat statio ion n batt batter ery y capa capaci city ty.. Depend Depending ing on the design design,, this this altern alternati ative ve could could requir requiree additi additiona onall mainte maintenan nance ce in the long long term term for shortshort-ter term m cost cost reduct reduction ions. s. Projec Projectt life life cost cost should should be consid considere ered d when evaluating evaluating the sources sources of field flashing. flashing. A rectifier rectifier can be used as the DC source if the station battery size can be reduced enough to provide economic justification. (4) (4) React Reactiv ivee droo droop p comp compen ensa sati tion on equi equipm pmen entt is needed for units operated in parallel on a common lowvoltag voltagee bus to preven preventt unequa unequall sharin sharing g of reacti reactive ve load. load. Reactive droop compensation reduces the generator output volt voltag agee slig slight htly ly as reac reacti tive ve outp output ut incr increa ease ses. s. The The net net effect effect is to stabil stabilize ize unit unit operat operation ion when when operat operating ing in parall parallel el and tendin tending g to preven preventt var load load swings swings betwee between n units. (5) Active Active droop compensation compensation (or “line drop” compensation) is simply a means of artificially relocating the point where the generator output voltage is sensed for the voltage voltage regulation regulation function. function. It consists consists of increasing increasing the generator output voltage in proportion to output current, to compen compensat satee for the voltag voltagee drop drop betwee between n the genera generator tor outp output ut term termin inal alss and and the the desi desire red d poin pointt on the the syst system em.. Active Active droop droop compen compensat sation ion should should be consid considere ered d if the gene genera rato torr is conn connec ecte ted d to the the syst system em thro throug ugh h a high high impedance impedance unit transforme transformerr or to a long high-impedan high-impedance ce transmis transmission sion line. Line drop compensati compensation on is usually not requir required ed unless unless needed needed for power power transm transmiss ission ion system system voltage voltage stability. stability. This requireme requirement nt will be establishe established d by the power transmis transmission sion authorit authority. y. When used with autoautomatic matic voltag voltagee contro controll that that derive derivess its contro controlle lled-v d-valu aluee input from the same, or nearly the same, point as the line drop drop compen compensat sation ion featur feature, e, cautio caution n should should be used used to ensure ensure that that the automa automatic tic voltag voltagee contro controll system system is not counteracting the effects of the voltage regulator line drop compensat compensation ion feature. feature. Close coordinat coordination ion with the power transmission authority is required to ensure power system voltage stability. (6) Power System Stabiliz Stabilizer er (PSS) equipment equipment should be used used on genera generator torss large large enough enough to have have a positi positive ve effect effect on power system stabili stability. ty. The PSS function function tends to damp out generator rotor oscillations by controlling the excita excitatio tion n system system output output in phase phase opposi oppositio tion n to power power syst system em oscill oscillat atio ions ns to damp them them out. out. PSS PSS work workss by sensin sensing g an input input from from the power system system and reacti reacting ng to
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EM 1110-2-3006 30 Jun 94 oscillati oscillations ons in the power system. system. These oscillati oscillations ons typically show up in the unit as rotor angle oscillations and if allowed to continue to build up in conjunction with other synchronous machines in the system, set up unacceptable power swings between major loads and major generating plants in a widely dispersed power distribution grid. h. Excitation Excitation system instrument instrument transformer transformerss.
Ded Dedicated cated curren currentt and potent potential ial transf transform ormers ers should should be supsupplied plied to service service the excitation excitation system system voltage voltage regulator regulators. s. They can often be advantageously mounted in metal-clad switchgear switchgear,, cubicles, cubicles, or metal-enc metal-enclosed losed bus runs, where they are associate associated d with similar similar instrumen instrumentt transform transformers ers for meterin metering g and relay relay servic service. e. The latter latter are furnis furnished hed and and moun mounte ted d by the the manu manufa fact ctur urer er of the the cubi cubicl cles es or buses, and a better layout can usually be devised, where all instrument transformers are of the same general form, than would result if space were provided for field installation of transform transformers ers supplied with the voltage regulator. regulator. Multiple-secondary current transformers save considerable spac space. e. The The guid guidee spec specif ific icat atio ions ns prov provid idee for for alte altern rnat atee methods of procurement, assuming that the general design of buses buses and genera generator tor leads leads will will have have been been determ determine ined d before the generator is awarded.
3-7. Generator Generator Stator Stator a. Stator Stator core core stamping stampingss. The stator stator prima primary ry compocomponent nent is the thin sheet sheet steel steel stampi stampings ngs that, that, when when stacke stacked d together together and clamped, clamped, form the stator core. The stamping stamping shap shapes es are are so desi design gned ed that that when when they they are are corr correc ectl tly y stacked, they will form stator winding coil slots, with no stamping stamping protruding protruding into into the slot. Uneven slots slots are detrimental mental to coil life in several several ways: wear wear on ground ground wall insulation insulation armor tape; prevention prevention of adequate adequate tightenin tightening g of coil in the slot; and, in extreme cases, erosion of the ground wall insulation. b. Stator Stator frame frame.
(1) (1) The The stat stator or fram framee is desi design gned ed for for rigi rigidi dity ty and and strength to allow it to support the clamping forces needed to retain the stator punchings in the correct core geometry. Strength Strength is needed for the core to resist resist deformation deformation under fault fault conditions conditions and system disturbances disturbances.. Also, the core is subjected to magnetic forces that tend to deform it as the rotor rotor field rotate rotates. s. In a few large large size machin machines, es, this flexing has been known to cause the core to contact the the roto rotorr duri during ng oper operat atio ion. n. In one one inst instan ance ce,, the the core core defo deform rmed ed and and cont contac acte ted d the the roto rotor, r, the the mach machin inee was was tripped by a ground fault, and intense heating caused local stator tooth iron melting, which damaged the stator winding ground wall insulation.
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(2) Even Even if the rotor rotor and the stator stator core do not come in contact, contact, the varying varying air gap is a proble problem. m. In machine machiness with with split split phase phase windin windings gs where where the split split phase phase curren currents ts are monitored for machine protection, the variation in the air gap causes a corresponding variation in the split phase curren currents. ts. If the variati variations ons are signif significa icant, nt, the machin machinee will will trip trip by differ different ential ial relay relay action action,, or the differ different ential ial relays relays will will have have to be desens desensiti itized zed to preven preventt trippi tripping. ng. Desens Desensiti itizin zing g the relays relays will will work, work, but it reduce reducess their their effect effective ivenes nesss in protec protectin ting g the machin machinee from from intern internal al faults. (3) Furthe Furtherr readin reading g on this subject subject can be found in the IEEE Transactions on Power Apparatus and Systems, Vol PAS-102, Nos. 9 and 10, and in the AIEE Transactions of October 1953, as Paper 53-314. c. Stator Stator assem assembly bly. Small Small stator stator assembl assemblies ies that that can be ship shippe ped d in one one or two two piec pieces es shou should ld be comp comple lete tely ly assembled assembled at the factory. factory. If the stator stator frame assembly assembly has to be shipped shipped in more more than than two pieces, pieces, the core core should should probably probably be stacked in the field. Field Field stacking will will avoid splits splits in the stator stator core, core, the major major source source of stator stator core problems. problems. Stator Stator frames are generally generally built built at the factory in sections that are as large as can be shipped to the erection tion site site.. Stat Stator or asse assemb mbly ly is comp comple lete ted d in the the fiel field d by bolting the sections together, stacking the core iron laminations, ations, and winding the stator. stator. Field stacking stacking of the stator core results in a higher initial cost for the generator, but provid provides es better better service service life life and is prefer preferred red.. Genera Generator tor Guide Specificatio Specification n CW-16120 CW-16120 contains contains a discussio discussion n on stator assembly. d. Multitur Multiturn n coil coil stator stator winding windingss. On small smaller er gener gener-ators, and on certain sizes of larger machines, stator windings ings empl employ oyin ing g mult multip iple le turn turn coil coilss are are used used.. This This effective effectively ly inserts inserts more coils per armature armature slot, giving giving a high higher er gene genera rate ted d volt voltag agee per per slot slot as comp compar ared ed with with a single single turn bar winding. winding. With With this this windin winding g design design,, the stator winding is divided into two or more parallel paths per phase. phase. On the neutral neutral ends ends of the windin winding, g, one half of each phase is connected to the ground point through a curren currentt transf transform ormer er (CT) (CT) of carefu carefully lly select selected ed ratio ratio and character characteristic istics. s. On the generator generator output, output, other CTs measure the total phase current. current. Different Differential ial relays relays compare the split phase current and total phase current; an internal generator fault that results in unbalanced current between the the phas phasee halv halves es can can usua usuall lly y be dete detect cted ed and and the the unit unit tripped off quickly enough to prevent serious damage. e. Roebel Roebel bar stator stator winding windingss. For large large generat generators ors,,
windin winding g design designss using using single single turn turn coils coils are prefer preferred red,, in which which case case the neutral neutral termi terminal nalss are not divide divided d and a
EM 1110-2-3006 30 Jun 94 different arrangement of CTs for the differential relays is required. required. The single turn coils coils use a Roebel transpos transpositio ition, n, rather rather than than separa separate te turns, turns, to balanc balancee curren currentt in the conconductor ductors. s. This This elimin eliminate atess the possibil possibility ity of turn-t turn-to-t o-turn urn faults faults,, which which are a common common cause cause of windin winding g failur failures. es. Single turn coils cannot be used on machines with short bore heights because there is not sufficient room to make the Roebel transposi transposition. tion. There are also certain certain configuconfigurations of large machines which do not allow the use of single turn coils.
3-8. 3-8. Rotor Rotor and Shaf Shaftt a. Rotor Rotor assem assembly bly.
(1) Large Large genera generator tor rotors rotors must must be assemb assembled led in the powerhouse powerhouse.. Manufactu Manufacturing ring practice practice provides two types, one in which the hub and arms are made of cast steel, the other other with with a cast cast or fabric fabricate ated d hub to which which are bolted bolted and and keye keyed d the the fabr fabric icat ated ed roto rotorr arms arms.. For For roto rotors rs with with bol boltedted-on on arms, rms, a means eans of acce access ss to insp inspec ectt and and re-tig re-tighte hten n the bolts should should be specif specified ied.. Some Some medium medium-sized units have been built with rotors of stacked sheets, but this type is limited by the rolling width of the sheets. With With both both types types the rotor rotor rim is built up of sheet steel steel punchings. (2) Pole pieces, pieces, assembled assembled and wound in the factory, factory, are usually made with a dovetail projection to fit slots in the rim punchin punchings. gs. The pole pieces pieces are assemble assembled d to the rotor using wedge-shaped keys, two keys per pole piece. The field assembly assembly program should make provisions provisions for handli handling ng large large pole pole pieces pieces withou withoutt tying tying up the powerpowerhouse bridge crane. b. Genera Generator tor shafts shafts.
(1) Generator Generator shafts shafts 12-in. and larger larger diameter should should be gun-ba gun-barre rrell drille drilled d full full length length.. This This bore bore facili facilitat tates es inspection of the shaft forging, and in the case of Kaplan units, provides a passage for the two oil pipes to the blade servo-mot servo-motor or in the turbine turbine shaft. shaft.
manufacturer) to which the rotor hub or shaft flange can be bolted. (3) If the design design of the rotor and shaft provide providess for a permanent connection between the shaft and rotor hub, it may be necess necessary ary to locate locate the rotor rotor erecti erection on plate plate in a floor recess, or on a pedestal on the floor below the erection tion spac space, e, unde underr a hole hole in the the floo floorr prov provid ided ed for for the the shaft. shaft. Also, Also, if the comple complete te rotor rotor is to be assemb assembled led on a long shaft which extends below the rotor hub before the shaft and rotor are placed in the stator, it may be convenient nient to provid providee a hole hole in the erecti erection on floor so that that the lower end of the shaft will rest on the floor below, thus minimi minimizin zing g the crane crane lift lift during during rotor rotor assemb assembly. ly. When When the shaft must be handled with the rotor in assembling the generator, the crane clearance above the stator frame may be affected.
3-9. 3-9. Bra Brakes kes and and Jacks Jacks The brakes, brakes, which which are used to stop stop rotati rotation on of the unit, unit, are actuated actuated by 100-ps 100-psii air pressure pressure and are designed designed to serve as rotor jacks when high-pressure oil is substituted for air. air. As far as the generato generatorr alone is concer concerned ned,, the distance the rotor is to be lifted by the jacks depends on the the spac spacee requ requir ired ed to chan change ge a thru thrust st bear bearin ing g shoe shoe.. Blocks should be provided to hold the rotor in the raised positi position on without without dependin depending g on the jacks. jacks. The usual usual lift lift required required to service service a bearing is approximat approximately ely 2 in. If the gene genera rato torr is to be driv driven en by a Kapl Kaplan an turb turbin ine, e, the the lift lift must provide space for disconnecting the Kaplan oil piping. ing. This This lift lift may may be as much as 12 in. in. The The genera generato torr manu manufa fact ctur urer er can can usua usuall lly y desi design gn for for this this extr extraa lift lift so noth nothin ing g on the the gene genera rato torr need need be dist distur urbe bed d exce except pt to remove remove the collector collector brush rigging. rigging. Motor-oper Motor-operated ated jacking ing oil oil pump pumpss can can be perm perman anen entl tly y conn connec ecte ted d to larg largee unit units. s. Medi Medium um-s -siz ized ed and and smal smalle lerr gene genera rato tors rs can can be served served with a portable portable motor-oper motor-operated ated oil pump. MotorMotoroper operat ated ed pump pumpss shou should ld be prov provid ided ed with with suit suitab able le oil oil supply and sump tanks so the oil system will be complete and independent of the station lubricating oil system.
3-10. 3-10. Bea Bearing rings s (2) (2) Gene Genera rato tors rs desi design gned ed with with the the thru thrust st bear bearin ing g loca locate ted d belo below w the the roto rotorr usua usuall lly y have have eith either er a bolt bolted ed conn connec ecti tion on betw betwee een n the the bott bottom om of the the roto rotorr hub hub and and a flange on the shaft, or the shaft projects through a hole in the hub and is keyed to it. Provis Provision ionss in the powerh powerhous ousee for rotor erection should consider the floor loading of the rotor weight, concentrated on the area of the shaft hub or the the roto rotorr flan flange ge,, supp suppor orte ted d by the the powe powerh rhou ouse se floo floor. r. Includ Includee a plate plate in the floor floor (inclu (included ded with with the generato generatorr spec specif ific icat atio ions ns and and to be supp suppli lied ed by the the gene genera rato torr
a. Thrust Thrust bearing bearing loading loading. The thrus thrustt bearing bearing in the the
genera generator tor is the most most import important ant bearin bearing g elemen elementt in the gene genera rato torr-tu turb rbin inee asse assemb mbly ly as it carr carrie iess not not only only the the weight weight of the rotating rotating genera generator tor parts, parts, but the weight weight of the turbine turbine shaft shaft and turbin turbinee runner runner,, in additi addition on to the hydrau hydraulic lic thrust thrust on the runner. runner. The allowab allowable le hydrau hydraulic lic thrust provided in standard generator design is satisfactory for for use use with with a Fran Franci ciss runn runner er,, but but a Kapl Kaplan an runn runner er requires requires provision provision for higher-th higher-than-no an-normal rmal thrust thrust loads. loads. It
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EM 1110-2-3006 30 Jun 94 is important that the generator manufacturer have full and accurate information regarding the turbine. b. Thrust Thrust bearing bearing types.
The The most most commo commonl nly y used used types of thrust thrust bearings bearings are the Kingsbury, Kingsbury, the modified modified Kingsbury, Kingsbury, and the spring-suppo spring-supported rted type. The spherical spherical type of thrust bearing has not been used on any Corps of Engine Engineers ers’’ genera generator tors. s. All of these these types types have the bearing ing part partss imme immers rsed ed in a larg largee pot pot of oil oil that that is cool cooled ed eith either er by wate waterr coil coilss imme immers rsed ed in the the oil oil or by the the oil oil pumped through a heat-exchanger mounted near the bearing. ing. These These various various types of bearin bearings gs are fully fully describe described d in availa available ble texts, texts, such such as “The “The Mechan Mechanica icall Engine Engineers ers’’ Handbo Handbook” ok” (Marks (Marks 1951) 1951) and “Mecha “Mechanic nical al Engine Engineers ers’’ Handbook” (Kent 1950).
temper temperatu ature re detect detector or (RTD) (RTD) device devices, s, and a temper temperatu ature re rela relay y (Dev (Devic icee 38). 38). The The dial dial port portio ions ns of the the indi indica cati ting ng thermometers are grouped on a panel which can be part of the governor cabinet, mounted on the generator barrel, or on another panel where they can be easily seen by maintenance personnel or a roving operator. b. Dial indicato indicatorr alarms alarms.
The The dial dial indic indicat ator or alarm alarm contacts are set a few degrees above the normal bearing operating operating temperatur temperatures es to prevent prevent nuisance nuisance alarms. When approa approachi ching ng their their alarm alarm setpoi setpoint, nt, these these contac contacts ts tend tend to bounce and chatter. chatter. If they are used with event recorder recorders, s, they they can can prod produc ucee mult multip iple le alar alarms ms in rapi rapid d succ succes essi sion on unless some means are used to prevent this. c. RTDs RTDs.
c. Thrust Thrust bearing lubricatio lubrication n. The basic basic prin princip ciple le of
oper operat atio ion n of all all bear bearin ing g type typess requ requir ires es a film film of oil oil between the rotating bearing plate and the babbitted stationar tionary y shoes. shoes. The rotatin rotating g parts parts on some some machin machines es are so heavy that when the machine is shut down for a few hours, the oil is squeezed out from between the bearing surfac surfaces es and it is necess necessary ary to provid providee means means to get oil between the babbitted surface and the bearing plate before the unit is starte started. d. Specif Specifica icatio tions ns for generat generators ors above 10 MW , and for generato generators rs in unmann unmanned ed plants plants,, should should requir requiree provis provision ionss for automa automatic ticall ally y pumpin pumping g oil under under high pressure between the shoes and the runner plate of the thrust bearing just prior to and during machine startup, and when stopping the machine. d. Guide Guide bearings bearings.
A guid guidee bearin bearing g is usual usually ly proprovided adjacent to the thrust bearing and is lubricated by the oil in the thrust thrust bearing bearing pot. Except Except for Kaplan units, units, machin machines es with with guide guide bearin bearings gs below below the rotor rotor seldom seldom require require an upper guide bearing. bearing. When the thrust thrust bearing is abov abovee the the roto rotor, r, a lowe lowerr guid guidee bear bearin ing g is requ requir ired ed.. Two guide bearings should always be provided on generators tors for use with Kaplan Kaplan turbin turbines. es. These These separate separate guide guide bearings bearings have self-contai self-contained ned lubricatin lubricating g systems. Oil in the bearings seldom needs to be cleaned or changed, but when when cleani cleaning ng is necess necessary ary,, the prefer preferred red practi practice ce is to completely drain and refill the unit when it is shut down. Valves on oil drains should be of the lock-shield type to mini minimi mize ze poss possib ibil ilit ity y of acci accide dent ntal al drai draini ning ng of the the oil oil during operation.
3-11. Temperature Temperature Devices a. Types Types of temper temperatu ature re device devicess. All All gener generat ator or and and turbine turbine bearings bearings are specified specified to have three temperat temperature ure sensing sensing devices: a dial-type dial-type indicating indicating thermometer thermometer with adju adjust stab able le alar alarm m cont contac acts ts,, embe embedd dded ed resi resist stan ance ce
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RTD RTD lead leadss are are brou brough ghtt out out to termi termina nall blocks, which are usually mounted in the generator terminal cabinet cabinet on the generator generator air housing. housing. Turbine Turbine bearing bearing RTD leads should be terminated in the same place as the genera generator tor RTD leads. leads. For bearing bearingss equipp equipped ed with more more than one RTD, it is usually adequate to monitor only one, and let the other(s) other(s) serve serve as spares. Thrust Thrust bearings bearings may have have six or more more RTDs. RTDs. Moni Monito tori ring ng three three or four four of them them is usuall usually y satisf satisfact actory ory.. Genera Generator tor stator stator windin windings gs usua usuall lly y have have severa severall RTDs RTDs per per phas phase. e. On the the larg larger er mach machin ines es,, moni monito torr two two RTDs RTDs per per phas phase, e, and and keep keep the the remainder as spares. d. RTD RTD moni monitor toring ing.
How the RTDs are used depe depend ndss part partly ly on the the deci decisi sion onss made made abou aboutt the the plan plantt control control system. system. They can be scanned scanned by the analog input input sectio section n of a remote remote terminal terminal unit (RTU) (RTU) if the plant is contro controlle lled d remote remotely, ly, or they they can be used used as inputs inputs to a local local standstand-alo alone ne scanne scannerr system system,, with with provis provision ionss for remote alarms and tripping the unit on high temperatures. In any case, case, perman permanent ent record recordss of bearin bearing g temper temperatu atures res are no longer retained. e. Contro Controll action action. Whethe Whetherr to alarm alarm or trip on RTD
temperatu temperature re indication indication depends on other decisions decisions about how the plant will be controlled, and what kind of control system system is used. For automated automated plants, plants, stator temperatur temperaturee increases can be used as an indication to reduce unit load automatically, for instance. f. Air temperature indicators. Air tempe temperat rature ure indiindi-
cators cators in air cooler cooler air streams streams are used to balanc balancee the coolin cooling g water flow, flow, and to detect detect cooler cooler proble problems. ms. Air temperatu temperature re alarms alarms should should be taken to the control point, or inpu inputt to the the plan plantt cont contro roll syst system em if the the plan plantt is automated.
EM 1110-2-3006 30 Jun 94 g. Temper Temperatu ature re relays relays.
Temper Temperatu ature re relays relays are typitypically used to shut the unit down on high bearing temperature tures, s, 105 105 °C or so. so. Sepa Separa rate te cont contac acts ts shou should ld also also be provided provided for alarming. alarming. Note that once a bearing temperatemperature ture reaches reaches the trip point, point, the damage damage has been been done. It is almost almost never possible possible to save the bearing. bearing. Tripping Tripping the unit promptly is done to save damage to other parts of the unit unit result resulting ing from failure failure of the bearing. bearing. Temper Temperatu ature re relay alarm points should be taken to the annunciator, and to the RTU or plant control control system. system. It is not necessary necessary to provid providee sequen sequence ce of event event record recording ing for the Device Device 38 beca becaus usee the the bear bearin ing g temp temper erat atur uree even eventt is such such a slow slow process.
(3) Special Special field field test (one (one unit of serial serial). ). These tests tests consist of: (a) Efficiency Efficiency tests. tests. (b) Heat Heat run tests tests.. (c) Machine Machine parameter parameter tests. tests. (d) Excitatio Excitation n test. test. (e) Overspeed Overspeed tests tests (optional). (optional). c. Testing Testing cconside onsideration rationss.
3-12. Final Acceptan Acceptance ce Tests Tests a. Genera Generall. Becaus Becausee of the size of water water wheel gengen-
erat erator ors, s, they they are are norm normal ally ly asse assemb mble led d in the the fiel field, d, and and because of their custom design, it is advisable to perform a series of acceptance and performance tests on the generator atorss duri during ng and and foll follow owin ing g thei theirr fiel field d asse assemb mbly ly.. The The purp purpos osee of thes thesee test testss is to ensu ensure re that that the the unit unitss meet meet contractu contractual al performan performance ce guarantees guarantees,, to provide provide a quality quality control check of field assembly work, and finally to provide a “bench mark” of “as-built” conditions serving as an aid in future future mainten maintenanc ancee and repair repair activi activitie ties. s. Certai Certain n field field tests tests are perform performed ed on every every genera generator tor of a serial serial (multi-un (multi-unit) it) purchase; other tests are performed on only one unit unit of the serial serial purcha purchase, se, e.g., e.g., tests tests for ensuring ensuring conformance with contractual guarantees. b. Fiel Field d acce accept ptan ance ce test testss and and spec specia iall fiel field d test testss.
These tests are as follows: (1) Field Field quality quality contro controll tests (all (all units). units). A series series of dielectric and insulation tests for the stator and field windings, performed performed during during field work, including including turn-to-t turn-to-turn urn tests, tests, coil transposit transposition ion group tests, tests, and semicondu semiconducting cting slot coating-to-stator iron resistance tests, to monitor field assembly techniques. (2) (2) Fiel Field d acce accept ptan ance ce test testss (all (all unit units) s).. consist of:
Thes Thesee test testss
(a) (a) Stat Stator or diel dielec ectr tric ic test tests. s. Thes Thesee test testss cons consis istt of: of: Insulation resistance and polarization index, Corona probe test, test, Corona Corona visibi visibilit lity y test, test, Final Final AC high high potent potential ial test, test, Partial discharge analysis (PDA) test, and Ozone detection (optional). (b) Rotor dielec dielectric tric tests. tests. (c) Stator Stator and rotor resistanc resistancee tests.
(1) (1) Plan Planni ning ng for for test testss on the the gene genera rato torr afte afterr its its installation should begin prior to completion of the generator specificat specifications. ions. Any generator generator that must be assembled assembled in the powerhouse will require field testing after installation to measure measure values of efficienc efficiency y and reactances, reactances, particula ticularly rly when when effici efficienc ency y guaran guarantee teess are includ included ed in the purcha purchase se specif specifica icatio tions. ns. The generato generatorr manufa manufactu cturer rer perf perfor orms ms thes thesee test testss with with a diff differ eren entt crew crew from from thos thosee employed employed for generator erection. erection. Specificat Specification ion CW 16120 requires a second generator in the powerhouse with special switching equipment and “back-fed” excitation system to permit permit performin performing g retardati retardation on tests used to determine determine generator generator efficiency. efficiency. In addition, special special arrangeme arrangements nts are required to use one of the generator-voltage class breakers as a shorting breaker during sudden short-circuit tests. (2) The manufactu manufacturer rer requires requires considerable considerable advance notice notice of desirable desirable testing testing dates in order to calibrate calibrate test instrumen instruments ts and ship in necessary necessary switchgear switchgear and excitaexcitation tion equipm equipment ent.. If the associat associated ed turbine turbine is to be given given a field efficiency test, it may be desirable to coordinate the turbin turbinee and genera generator tor tests tests so that that the electr electrica icall testin testing g instruments will be available to measure generator output during during the turbine turbine test. test. The heat run requir requires es a load load on the generator generator.. Normally, Normally, the generator generator is loaded loaded by connecting necting the generator generator output to the system system load. If system load isn’t sufficient to load the generator, IEEE 115 outlines alternative techniques to simulate load conditions. (3) The testing testing enginee engineerr may elect elect to use the plant plant instrumen instrumentt transform transformers ers instead instead of calibrate calibrated d current current and potential transformers if reliable data on plant instrument transformers are available. (4) Generator Generator erectors erectors usually usually apply dielectric dielectric tests on the armatu armature re (stato (stator) r) and field field windin windings gs before before the roto rotorr is put into the machi machine ne.. If the stator stator is woun wound d in the field, a high potential test is usually done once each
3-17
EM 1110-2-3006 30 Jun 94 day day on all of the the coil coilss inst instal alle led d duri during ng that that day. day. This This facilitates repairs if the winding fails under test and may prec preclu lude de miss missin ing g sche schedu dule led d “on“on-li line ne”” date dates. s. The The test test voltages voltages for these intermediat intermediatee tests tests must be planned planned so that each one has a lower value than the previous test, but greate greaterr than than the test test voltag voltagee specif specified ied for the final final high high potential test. (5) (5) IEEE IEEE 43 desc descri ribe bess the the pola polari riza zati tion on inde index x test test.. This index is the ratio of the insulation resistance obtained with a 10-min application of test voltage to that obtained with a similar similar application application for a 1-minute 1-minute period. RecomRecommended mended indices indices and recommende recommended d insulation insulation resistanc resistancee values are also given in the referenced standard. (b) Because Because of the relatively relatively small small amount of insulainsulation tion on the field field windin windings, gs, simple simple insula insulatio tion n (Megge (Megger) r) tests tests are adequa adequate te to determ determine ine their their readin readiness ess for the high-volta high-voltage ge test. test. Guide Specificatio Specification n CW-16120 CW-16120 requires the dielectric test to be made with the field winding connected to the collector rings and hence the test cannot be made made until until after after the genera generator tor is assemb assembled led with the DC leads of the static excitation system connected.
3-13. Fire Suppressi Suppression on Systems Systems Generators with closed air recirculation systems should be provid provided ed with with automa automatic tic carbon carbon dioxid dioxidee exting extinguis uishin hing g systems. systems. See Chapter Chapter 15 of EM 1110-2-420 1110-2-4205 5 for details. On larger open ventilated generators, water spray installations tions with with suitab suitable le detect detection ion system systemss to preven preventt false false tripping should be considered.
3-18
EM 1110-2-3006 30 Jun 94
Chapter 4 Power Transformers
4-1. 4-1. Genera Generall a. Type Type. Step Step-u -up p tran transf sfor orme mers rs for for use use with with main main unit unitss shou should ld be of the the oil oil imme immers rsed ed type type for for outd outdoo oorr operat operation ion,, with with a coolin cooling g system system as descri described bed in paraparagraph 4-3, 4-3, suited to the location. location. General General Corps of Engineers neers power power transf transform ormer er design design practi practice ce is covere covered d by Guid Guidee Spec Specif ific icat atio ion n for for Civi Civill Wo Work rkss Cons Constr truc ucti tion on CW-16320. b. ThreeThree-pha phase se transf transform ormers ers.
In the majority of applicatio applications, ns, three-phas three-phasee transform transformers ers should should be used for genera generator tor step-u step-up p (GSU) (GSU) applic applicati ations ons for the follow following ing reasons: (1) Higher Higher efficiency efficiency than three single-phase single-phase units of equivalent capacity. (2) Smaller Smaller space require requirement ments. s. (3) Lower instal installed led cost. cost. (4) Lower Lower probab probabili ility ty of failur failuree when when proper properly ly proprotected by surge arresters, thermal devices, and oil preservation systems. (5) Lower total total weight. weight. (6) (6) Redu Reduct ctio ion n in weig weight htss and and dime dimens nsio ions ns maki making ng larger capacities available within practical weight and size limitations. c. EHV applica applicatio tions ns. In applicat applications ions involvi involving ng interinterconnection to EHV (345 kV and above) systems, reliabil-
ity ity and and appl applic icat atio ion n cons consid ider erat atio ions ns dict dictat atee the the use use of single single-ph -phase ase units units due to lack lack of satisf satisfact actory ory indust industry ry experience experience with three-ph three-phase ase EHV GSU transform transformers. ers. The basic switching provisions discussed in Chapter 2 describe the the lowlow-vo volt ltag agee swit switch chin ing g sche scheme me used used with with EHV EHV transformers. d. Transf Transform ormer er featur features es.
Rega Regard rdlless ess of win winding ding configuration, for any given voltage and kVA rating, with normal temperature rise, the following features should be analyzed for their effect on transformer life cycle costs: (1) Type Type of coolin cooling. g.
(3) Departure Departure from normal normal design impedance. impedance. Examples of typical transformer studies which should be performed are contained in Appendix B of this manual. e. Transformer Transformer construc construction tion. There There are are two types types of constr construct uction ion used for GSU transf transform ormers ers.. These These are the core core form form type type and the shell shell form form type. type. Core Core form form transtransformers generally are supplied by manufacturers for lower voltage voltage and lower MVA rati rating ngs. s. The The core core form form unit unit is adapta adaptable ble to a wide wide range range of design design paramete parameters, rs, is ecoeconomical to manufacture, but generally has a low kVA-toweight weight ratio. ratio. Typical Typical HV ranges ranges are 230 kV and and less and 75 MVA and and less. Shell Shell form transf transform ormers ers have a high kVA-to-to-we weig ight ht rati ratio o and and find find favo favorr on EHV EHV and and high high MVA applicatio applications. ns. They have better short-circui short-circuitt strength strength charac character terist istics ics,, are less less immune immune to transi transitt damage damage,, but have a more labor-int labor-intensiv ensivee manufacturing manufacturing process. process. Both forms of construction are permitted by Corps’ transformer guide specifications.
4-2. 4-2. Rating Rating The full load kVA rating of the step-up transformer should be at least equal to the maximum kVA rating of the generat erator or or gene genera rato tors rs with with whic which h they they are are asso associ ciat ated ed.. Where Where transform transformers ers with auxiliary auxiliary cooling cooling faciliti facilities es have dual dual or trip triple le kVA ratings ratings,, the maximu maximum m transf transform ormer er rating should match the maximum generator rating.
4-3. 4-3. Cooling Cooling a. Genera Generall. The standard standard classes classes of transformer transformer cool
ing systems are listed in Paragraph 5.1, IEEE C57.12.00. Transformers, when located at the powerhouse, should be sited sited so unrest unrestric ricted ted ambien ambientt air circul circulati ation on is allowe allowed. d. The transformer rating is based on full use of the transformer cooling equipment. b. Forced Forced cooling cooling.
The The use of forced forced-a -air ir cooli cooling ng will will incr increa ease se the the cont contin inuo uous us self self-c -coo oole led d rati rating ng of the the transform transformer er 15 percent percent for transform transformers ers rated rated 2499 kVA and below, 25 percent for single-phase transformers rated 2500 2500 to 9999 9999 kVA and threethree-pha phase se transf transform ormers ers rated rated 2500 2500 to 11999 11999 kVA, and 33-1/3 33-1/3 percent percent for single-pha single-phase se transformers rated 10000 kVA and above and three-phase transform transformers ers rated rated 12000 kVA and and above. above. High-v High-velo elocit city y fans fans on the the larg larges estt size size grou groups ps will will incr increa ease se the the self self-cooled cooled rating rating 66-2/3 66-2/3 percent. percent. Forced Forced-oi -oill cooled cooled transtransformers, formers, whenever energized, energized, must be operated operated with the circulati circulating ng oil pumps operating. operating. Forced-oil Forced-oil transform transformers ers with air coolers do not have a self-cooled rating without
(2) Insulatio Insulation n level of high-volt high-voltage age winding. winding.
4-1
EM 1110-2-3006 30 Jun 94 the air-co air-cooli oling ng equipm equipment ent in operat operation ion unless unless they they are special units with a “triple rating.” c. Temperature Temperature consideratio considerations ns.
In dete determ rmin inin ing g the transf transform ormer er rating rating,, consid considera eratio tion n should should be given given to the temperatu temperature re conditions conditions at the point of installatio installation. n. High ambient temperatures may necessitate increasing the transformer former rating rating in order order to keep keep the windin winding g temper temperatu ature re within within permissible permissible limits. limits. If the temperatures temperatures will exceed thos thosee spec specif ifie ied d unde underr “Ser “Servi vice ce Cond Condit itio ions ns”” in IEEE IEEE C57.12 C57.12.00 .00,, a larger larger transfo transforme rmerr may be requir required. ed. IEEE IEEE C57.92 C57.92 should should be consul consulted ted in determ determini ining ng the rating rating required for overloads and high temperature conditions. d. Unusua Unusuall requir requireme ements nts. Clas Classs OA/ OA/FA and and Clas Classs FOA meet meet all the usual usual requir requireme ements nts for transf transform ormers ers loca locate ted d in hydr hydro o plan plantt swit switch chya yard rds. s. The The use use of trip triple le-rated rated transf transform ormers ers such such as Class Class OA/FA/ OA/FA/FA FA is seldom seldom required required unless unless the particular particular installation installation services services a load with a recurring short time peak. e. Class Class FOA transf transform ormers ers. On Clas Classs FOA tran transsformers, formers, there are certain certain considerat considerations ions regarding regarding static static electr electrifi ificat cation ion (build (build-up -up of charge charge on the transf transform ormer er windings windings due to oil flow). Transform Transformer er suppliers suppliers require require oil oil pump pump oper operat atio ion n when whenev ever er an FOA FOA tran transf sfor orme merr is energized. energized. Static Static electrificat electrification ion is important important to consider consider when designing the desired operation of the cooling, and can result in the following cooling considerations:
(1) Decrea Decrease se in oil flow flow veloci velocity ty requir requireme ements nts (for (for forced-oil cooled units). (2) Modifying Modifying of cooling equipment equipment controls controls to have pumps come on in stages. (3) Operation transformer.
of
pumps
prior
to
energizing
4-4. Electrical Electrical Characteri Characteristics stics a. Voltag Voltagee.
(1) (1) Volt Voltag agee rati rating ngss and and rati ratios os shou should ld conf confor orm m to ANSI ANSI C84.1 C84.1 preferre preferred d rating ratingss wherev wherever er possible possible.. The high-v high-volt oltage age rating rating should should be suitab suitable le for the voltag voltagee of the transm transmiss ission ion system system to which which it will will be connec connected ted,, with with proper proper consid considera eratio tion n for increa increases ses in transm transmiss ission ion voltag voltagee that that may be planned planned for the near future. future. In some cases cases this this may warran warrantt the constr construct uction ion of high-v high-volt oltage age windin windings gs for series series or parall parallel el operat operation ion,, with with bushin bushings gs for the higher voltage, or windings suitable for the higher voltage tapped for the present operating voltage.
4-2
(2) Considerat Consideration ion should also also be given to the voltage rating rating specifie specified d for the low-vo low-volta ltage ge windin winding. g. For plants plants conn connec ecte ted d to EHV EHV syst system ems, s, the the lowlow-vo volt ltag agee wind windin ing g rati rating ng shou should ld matc match h the the gene genera rato torr volt voltag agee rati rating ng to optim optimall ally y match match the genera generator tor’s ’s reacti reactive ve capabi capabilit lity y in “buc “bucki king ng”” the the tran transm smis issi sion on line line volt voltag age. e. For For 230230- kV transm transmiss ission ion system systemss and below, below, the transf transform ormer er lowlowvoltag voltagee rating rating should should be 5 perc percent ent below below the genera generator tor voltage rating to optimally match the generator’s reactive capabi capabilit lity y when when “boost “boosting ing”” transm transmiss ission ion line line voltag voltage. e. IEEE IEEE C57.11 C57.116 6 and EPRI EPRI EL-503 EL-5036, 6, Volume Volume 2, provid providee further further guidance guidance on considerat considerations ions in evaluating evaluating suitable voltage ratings for the GSU transformer. b. High-v High-volta oltage ge BIL. BIL.
(1) Basic Impulse Impulse Insulation Insulation Levels (BIL) associate associated d with the nominal nominal transmission transmission system voltage are shown in Table Table 1 of IEEE C57.12. C57.12.14. 14. With With the advent advent of metal metal oxide surge arresters, significant economic savings can be made in the procurement of power transformers by specifying reduced BIL levels in conjunction with the application of the appropriate metal oxide arrester for transformer surge surge protec protectio tion. n. To determ determine ine appropri appropriate ate values, values, an insulation coordination study should be made (see Appendix B for a study example example). ). Studies Studies involve involve coordinating coordinating and determini determining ng adequate adequate protective protective margins margins for the following transformer insulation characteristics: (a) Chopped-Wa Chopped-Wave ve Withstand Withstand (CWW). (CWW). (b) Basic Impulse Impulse Insulatio Insulation n Level (BIL). (c) Switching Switching Surge Surge Level (SSL). (SSL). (2) (2) If ther theree is reas reason on to beli believ evee the the tran transm smis issi sion on system presently operating with solidly grounded neutrals may be equipped equipped with regulatin regulating g transforme transformers rs or neutral neutral reactors reactors in the future, the neutral neutral insulatio insulation n level level should should be specified to agree with Table 7 of IEEE C57.12.00. c. Impeda Impedance nce.
(1) (1) Impe Impeda danc ncee of the the tran transf sfor orme mers rs has has a mate materi rial al effect on system stability, short-circuit currents, and transmission line regulation, and it is usually desirable to keep the imped impedanc ancee at the lower lower limit limit of normal normal impedanc impedancee design design values. values. Table Table 4-1 illust illustrat rates es the range range of values values availa available ble in a normal normal two-wi two-windi nding ng transf transform ormer er design design (values shown are for GSU transformers with
EM 1110-2-3006 30 Jun 94 Table 4-1 Nominal Design Impedance Limits for Power Transformers Standard Impedance Limits (Percent) AT EQUIV. 55 ° C kVA
HIGH-VOLTAGE WINDING
NOMINAL SYSTEM kV 15 25 34.5 46 69 11 5 13 8 161 230 500
WINDING BIL kV 110 150 200 250 350 450 550 650 825 1425
CLASS OA, OR SELF-COOLED RATING OF CLASS OA/FA OR CLASS OA/FA/FA MINIMUM MAXIMUM 5.0 5.0 5.25 5.60 6.1 5.9 6.4 6.9 7.5 10.95
7.5 7.5 8.0 8. 4 9.15 8.85 9.6 10.35 11.25 15.6
13.8-kV low low volt voltag age) e).. Impe Impeda danc nces es with within in the the limi limits ts shown shown are furnis furnished hed at no increa increase se in transf transform ormer er cost. cost. Transform Transformers ers can be furnished with lower or higher higher values ofimpedanc ofimpedancee at an increase increase in cost. The approximat approximatee effect of higher- or lower-than-normal impedances on the cost cost of transf transform ormers ers is given given in Table Table 4-2. The value value of transformer impedance should be determined giving consideration sideration to impacts impacts on selection selection of the interrupting interrupting capacities of station breakers and on the ability of the generator eratorss to aid in regula regulatin ting g transm transmiss ission ion line line voltag voltage. e. Transformer impedances should be selected based on system and plant fault fault study results results (see Chapter Chapter 2). ImpedImpedances shown are subject to a tolerance of plus or minus 7.5 percent. percent. (See IEEE IEEE C57.12.00). C57.12.00). Table 4-2 Increase In Transformer Cost For Impedances Above and Below The Standard Values STANDARD IMPEDANCE X 1.45-1.41 1.40-1.36 1.35-1.31 0.90-0.86 0.85-0.81 0.80-0.76
CLASS FOA OR CLASS FOW MINIMUM MAXIMUM
INCREASE IN TRANSFORMER COST 3% 2% 1% 2% 4% 6%
(2) In making comparis comparisons ons or specifying specifying the value of impedance of transformers, care should be taken to place all transform transformers ers on a common basis. basis. Impedance Impedance of a
8.3 4 8.3 4 8.75 9.34 1 0.1 7 9.84 10 . 6 7 11.50 12.5 18.25
12.5 12.5 1 4 . 33 1 4.0 15.25 14 . 75 16 . 0 1 7.2 5 18 .75 26.0
transformer is a direct function of its rating, and when a transf transform ormer er has more than than one differ different ent rating rating,, it has a diff differ eren entt impe impeda danc ncee for for each each rati rating ng.. For For exam exampl ple, e, to obtain the impedance of a forced-air-cooled transformer at the forced forced-ai -air-c r-cool ooled ed rating rating when when the impeda impedance nce at its self-cooled rating is given, it is necessary to multiply the impeda impedance nce for the self-coo self-cooled led rating rating by the ratio of the forced-air-cooled rating to the self-cooled rating. d. Transformer Transformer efficien efficiency cy. Transform Transformer er losses losses reprerepre-
sent sent a cons consid ider erab able le econ econom omic ic loss loss over over the the life life of the the power plant. plant. A study should should be made to select minimum minimum allowable allowable efficienc efficiencies ies for purposes purposes of bidding. bidding. Included Included in the the stud study y shou should ld be a dete determ rmin inat atio ion n of the the pres presen entt worth worth cost of transf transform ormer er losses. losses. This This value value is used used in evaluating transformer bids that specify efficiency values that exceed exceed the minimum minimum acceptable acceptable value. value. Examples Examples of typical studies are included in Appendix B of this manual. IEEE C57.120 provides provides further further guidance guidance on transform transformer er loss evaluation.
4-5. Terminals Terminals Where Where low-vo low-volta ltage ge leads leads betwee between n the transf transform ormer er and generator are of the metal-enclosed type, it is desirable to extend the lead housing to include the low-voltage terminals nals of the the tran transf sfor orme mer. r. This This arra arrang ngem emen entt shou should ld be indica indicated ted on the specif specifica icatio tion n drawin drawings gs and includ included ed in the specifications in order that the manufacturer will coordinate dinate his transf transform ormer er top details details with with the design design of the housin housing. g. It is someti sometimes mes prefer preferabl ablee to have the transtransformer former builder builder furnish furnish the housing over the low-voltag low-voltagee bushin bushings gs if it simpli simplifie fiess the coordina coordinatio tion. n. All bushing bushing
4-3
EM 1110-2-3006 30 Jun 94 charac character terist istics ics should should confor conform m to the requir requireme ements nts of IEEE C57.19.01. C57.19.01. The voltage voltage rating should should correspond correspond to the insulat insulation ion level level of the associ associate ated d windin winding. g. Where Where tran transf sfor orme mers rs are are inst instal alle led d at elev elevat atio ions ns of more more than than 3,30 3,300 0 ft abov abovee sea sea leve level, l, bush bushin ings gs of the the next next high higher er volt voltag agee clas classi sifi fica cati tion on may may be requ requir ired ed.. Bush Bushin ings gs for for neutral neutral connection connectionss should should be selected selected to suit the insulainsulation level of the neutral, as discussed in paragraph 4-4.
4-6. Accessories Accessories a. Oil preservat preservation ion systems systems. Three Three differ different ent oil oil prespreservati ervation on system systemss are availabl available, e, as descri described bed below. below. The firs firstt two two syst system emss are are pref prefer erre red d for for gene genera rato torr step step-u -up p transformers:
(1) Inert Inert gas pressur pressuree system. system. Positi Positive ve nitroge nitrogen n gas pressure is maintained in the space between the top of the oil and the tank cover from a cylinder or group of cylinders through a pressure-reducing valve. (2) Air-cell, Air-cell, constant-press constant-pressure, ure, reservoir reservoir tank system. system. A system of one or more oil reservoirs, each containing an air cell arranged to prevent direct contact between the oil and the air. (3) Sealed Sealed tank. tank. Gas is admit admitted ted to the space space above above the the oil oil and and the the tank tank is seal sealed ed.. Expa Expans nsio ion n tank tankss for for the the gas are provided provided on some sizes. Sealed Sealed tank constructio construction n is employed for 2,500 kVA and smaller sizes. b. Oil Oil flow flow alar alarm m.
Tran Transf sfor orme mers rs that that depe depend nd upon pump pumped ed circ circul ulat atio ion n of the the oil oil for for cool coolin ing g shou should ld be equipped with devices that can be connected to sound an alarm, to prevent closing of the energizing power circuit, or to deenergize deenergize the transfor transformer mer with loss loss of oil flow. In forced-oil forced-oil-cool -cooled ed units, units, hot spot detectors detectors should be provided which can be connected to unload the transformer if the the temp temper erat atur uree exce exceed edss that that at whic which h the the seco second nd oil oil pump pump is expect expected ed to cut cut in. in. FOA trans transfo form rmer erss shou should ld employ control schemes to ensure pump operation prior to energizing the transformer. c. Surge Surge arrest arresters ers.
Surg Surgee arre arrest ster erss are are loca locate ted d near near the transf transform ormer er termin terminals als to provid providee protec protectio tion n of the high-v high-volt oltage age winding windings. s. Normal Normal practic practicee is to provid providee brackets on the transformer case (230- kV HV and below) for mounting the selected surge arrester. d. Fans Fans and pumps pumps. The axial-fl axial-flow ow fans provide provided d for supplemen supplementary tary cooling on Class OA/FA transform transformers ers are equipped with special motors standardized for 115-V and 230-V single-pha single-phase se or 208-V three-phas three-phasee operation. operation. Like-
4-4
wise, oil circulating pumps for FOA transformers are set up for single-ph single-phase ase AC service. service. Standard Standard Corps of EngiEngineers neers practi practice ce is to supply supply 480-V, 480-V, threethree-pha phase se power power to the transf transform ormer er and have have the transf transform ormer er manufa manufactu cturer rer provide necessary conversion equipment. The detection of certain gases, generated in an oil-filled transformer in service, is frequently the first available indication of possible possible malfunction malfunction that may eventually eventually lead to the transfor transformer mer failure failure if not correcte corrected. d. The monitori monitoring ng system can provide gas analysis of certain gases from gas spaces spaces of a transformer. transformer. The system system output contacts contacts can be connected for an alarm or to unload the transformer if the gas levels levels exceed exceed a set point. point. The type type of gases gases generated erated,, during during the abnorm abnormal al transf transform ormer er condit condition ions, s, is described in IEEE C57.104. e. On-line On-line dissol dissolved ved gas monitor monitoring ing system. system.
f. Temperature detectors. A dial dial-t -typ ypee temp temper erat atur uree indicating device with adjustable alarm contacts should be provid provided ed for oil temper temperatu ature re indica indicatio tion. n. Windin Winding g RTDs RTDs should should be provid provided, ed, and monito monitored red by the plant plant contro controll system system or a standstand-alo alone ne temper temperatu ature re record recorder, er, if one is provid provided ed for the genera generator tor and turbine turbine RTDs. RTDs. At least least two RTDs in each winding should be provided. g. Lifting Lifting devices devices.
If powe powerh rhou ouse se crane craness are to be used for transform transformer er handling, handling, the manufactur manufacturer’s er’s design design of the lifting lifting equipment equipment should be carefully carefully coordinated coordinated with the crane clearance and with the dimensions of the crane crane hooks. hooks. The lifting lifting equipme equipment nt should should safely safely clear bushings bushings when handling handling the completely completely assembled assembled transtransformer former,, and should should be proper properly ly design designed ed to compen compensat satee for eccent eccentric ric weight weight dispos dispositi itions ons of the comple complete te transtransformer with bushings. h. On-line On-line monitor monitoring ing system systemss. In addi addittion ion to the the on-lin on-linee dissol dissolved ved gas monito monitorin ring g system system descri described bed in paragraph 4-6 e, othe otherr on-l on-lin inee syst system emss are are avai availa labl blee to monitor abnormal abnormal transformer transformer conditions. These include:
(1) Partial Partial discharge discharge analysis. analysis. (2) Acoustical Acoustical monito monitoring ring.. (3) Fiber-opti Fiber-opticc winding winding temperature temperature monitoring. monitoring. (4) Bearing Bearing wear sensor sensor (forced-oil-c (forced-oil-cooled ooled units). units). (5) Load Load tap changer changer monitor monitor (if load load tap changer changerss are used).
EM 1110-2-3006 30 Jun 94 Early detection of the potential for a condition leading to a forced outage of a critical transformer bank could more than than offs offset et the the high high init initia iall cost costss of thes thesee tran transf sfor orme merr accessories by avoiding a more costly loss of generation. i. Dial-ty Dial-type pe indica indicating ting device devicess.
Dial-t Dial-type ype indi indicat cating ing
devices should be provided for: (1) Liquid Liquid level indicat indication. ion. (2) Liquid Liquid temperature temperature indicator indicator.. (3) Oil flow indicato indicators rs (see paragraph paragraph 4-6b). These are in addition to the dial-type indicators that are part of the winding temperature systems (see paragraph 4-6 f ). ).
4-7. Oil Containmen Containmentt Systems Systems If any oil-filled transformers are used in the power plant, provisions are made to contain any oil leakage or spillage result resulting ing from a ruptur ruptured ed tank tank or a broken broken drain valve. valve. The volume volume of the contai containme nment nt should should be suffic sufficien ientt to retain all of the oil in the transformer to prevent spillage into waterways or contamination of soil around the transformer former foundations. foundations. Special Special provisions provisions (oil-wate (oil-waterr separaseparators, oil traps, etc.) must be made to allow for separation of oil spilla spillage ge versus versus normal normal water water runoff runoff from from storms storms,, etc. etc. IEEE IEEE 979 and 980 provide provide guidan guidance ce on design design conconsiderations for oil containment systems.
transf transform ormers ers are locate located d in close close proxim proximity ity to adjace adjacent nt transform transformers, ers, plant equipment, equipment, or power plant structures. structures. Oil-filled transformers contain the largest amount of combustib bustible le materi material al in the power plant plant and so requir requiree due consideration of their location and the use of fire suppression measures. measures. Fires in transformer transformerss are caused caused primarily primarily from from breakd breakdown own of their their insula insulatio tion n system systems, s, althou although gh bushin bushing g failur failures es and surge surge arrest arrester er failur failures es can also also be causes. causes. With failure failure of the transformer’ transformer’ss insulation insulation system, internal arcing follows, follows, creating creating rapid internal internal tank pressures pressures and possible possible tank rupture. rupture. With a tank rupture, rupture, a larg largee volu volume me of burn burnin ing g oil oil may may be expe expell lled ed over over a large area, creating the possibility of an intense fire. b. Suppre Suppressi ssion on measur measures es. Supp Suppre ress ssio ion n meas measur ures es include the use of fire quenching pits or sumps filled with coarse coarse rock surroundi surrounding ng the transform transformer er foundatio foundation n and phys physic ical al sepa separa rati tion on of the the tran transf sfor orme merr from from adja adjace cent nt equipment equipment or structures. structures. Physical Physical separation separation in distance is also augmented by the use of fire-rated barriers or by firerated building wall construction when installation prevents mainta maintaini ining ng minimu minimum m recomm recommend ended ed separa separatio tions. ns. EcoEconomical nomical plant arrangement arrangementss generally generally result in less than recommende recommended d minimums minimums between between transform transformers ers and adjacent structures so water deluge systems are supplied as a fire fire preven preventio tion n and suppress suppression ion techniqu technique. e. The system systemss should should be of the dry pipe pipe type type (to prevent prevent freeze-u freeze-up p in cold cold weathe weather) r) with with the system system deluge deluge valves valves actuat actuated ed either by thermostats, by manual break-glass stations near the transform transformer er installat installation, ion, or by the transform transformer er differdifferential protective relay.
4-8. Fire Suppress Suppression ion Systems Systems a. Genera Generall. Fire suppressi suppression on measures measures and protective protective
equipment should be used if the plant’s oil-filled
4-5
EM 1110-2-3006 30 Jun 94
Chapter 5 High-Voltage High-Voltage System
and disadv disadvant antage agess of variou variouss high-v high-volt oltage age switch switching ing schemes is included in this chapter. a. Minimum Minimum requir requireme ements nts.
5-1. Definition Definition The high-voltage system as treated in this chapter includes all equipment equipment and conductors conductors that carry current current at transmissio mission n line-v line-volt oltage age,, with with their their insula insulator tors, s, suppor supports, ts, switching switching equipment, equipment, and protective protective devices. devices. The system begi begins ns with with the the high high-v -vol olta tage ge term termin inal alss of the the step step-u -up p power transformers and extends to the point where transmissio mission n lines lines are attach attached ed to the switch switchyar yard d struct structure ure.. High-volta High-voltage ge systems systems include include those those systems systems operating operating at 69 kV and above, above, althou although gh 34.534.5-kV and 4646-kV systems that are subtransmission-voltage systems are also covered in this this chap chapte ter. r. Tran Transm smis issi sion on line line corr corrid idor orss from from the the powe powerh rhou ouse se to the the swit switch chya yard rd shou should ld allo allow w adeq adequa uate te cleara clearance nce for mainte maintenan nance ce equipm equipment ent access access,, and clear clear workin working g space. space. Workin Working g cleara clearance ncess shall shall be in accoraccordance with the applicable sections of ANSI C2, Part 2.
5-2. Switchyard Switchyard a. Spac Spacee arou around nd the the switc switchy hyar ard d .
Adeq Adequa uate te spac spacee should be allowed to provide for extension of the switchyard facilities when generating units or transmission lines are are adde added d in the the futu future re.. The The imme immedi diat atee surr surrou ound ndin ings gs should permit the building of lines to the switchyard area from from at least least one direct direction ion without without the need for heavy dead-end structures in the yard. b. Switchyard Switchyard location location. Subjec Subjectt to these crit criteri eria, a, the
switchyard should be sited as near to the powerhouse as space permits, in order to minimize the length of control circuits and power feeders and also to enable use of service facilities located in the powerhouse. c. Switch Switchyar yard d fencin fencing g. A chain link woven wire fence not less than 7 ft high and topped with three strands of barbed wire slanting outward at a 45-deg angle, or concertin certinaa wire, wire, with with lockab lockable le gates, gates, should should be provid provided ed to enclose enclose the entire yard. Other security security consider consideration ationss are discussed in EM 1110-2-3001.
5-3. Switching Switching Scheme The type type of high-v high-volt oltage age switch switching ing scheme scheme should should be selected after a careful study of the flexibility and protection tion needed needed in the statio station n for the initia initiall instal installat lation ion,, and also when the station is developed to its probable maximum capacit capacity. y. A detail detailed ed discussi discussion on of the advant advantage agess
The The init initia iall inst instal alla lati tion on may requir requiree only only the connec connectin ting g of a single single transf transform ormer er bank bank to a single single transm transmiss ission ion line. line. In this case, case, one circuit cuit brea breake ker, r, one one set set of disc discon onne nect ctss with with grou ground ndin ing g blades blades,, and one bypass bypass discon disconnec nectin ting g switch switch should should be adequa adequate. te. The high-vol high-voltag tagee circui circuitt breake breakerr may even be omit omitte ted d unde underr some some cond condit itio ions ns.. The The rece receiv ivin ing g util utilit ity y generally generally establishes establishes the system system criteria criteria that will dictate the need for a high side breaker. b. Bus struc structur turee. When When another another powerho powerhouse use unit unit or
transm transmiss ission ion line line is added, added, some some form form of bus struct structure ure will will be requir required. ed. The origin original al bus structur structuree should should be design designed ed with with the possib possibili ility ty of becomi becoming ng a part part of the ultimate ultimate arrangemen arrangement. t. Better Better known arrangements arrangements are the main main and transfer transfer bus scheme scheme,, the ring bus scheme, scheme, the breake breaker-a r-andnd-a-h a-half alf scheme scheme,, and the double double bus-do bus-doubl ublee breaker scheme. c. Main and and transfer transfer bus scheme scheme.
(1) (1) The The main main and and tran transf sfer er bus bus sche scheme me,, Figu Figure re 5a, 5a, consis consists ts of two indepe independe ndent nt buses, buses, one of which which is nornormally mally energized. energized. Under normal normal conditions, conditions, all circuits circuits are tied tied to the main bus. bus. The transf transfer er bus is used used to provide provide serv servic icee thro throug ugh h the the tran transf sfer er bus bus tie tie brea breake kerr when when it becomes necessary to remove a breaker from service. (2) Advantages Advantages of the main and transfer transfer bus arrangearrangement include: (a) Continuit Continuity y of service and protection protection during during breaker maintenance. (b) Ease of of expansion expansion.. (c) Small land land area requiremen requirements. ts. (d) Low cost. cost. (3) Disadvanta Disadvantages ges include: include: (a) Breaker Breaker failure failure or bus fault causes the loss loss of the entire station. (b) Bus tie breaker breaker must have protection protection schemes schemes to be able to substitute for all line breakers. (c) An additional additional tie breaker breaker is required. required.
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EM 1110-2-3006 30 Jun 94 (d) Double Double feed to each each circuit. circuit. (e) Expandable Expandable to breaker-and-a breaker-and-a-hal -halff scheme. scheme. (3) Disadvanta Disadvantages ges include: include: (a) Each circuit circuit must have its own potential potential source. source. (b) Usually Usually limited limited to four circuits. circuits. e. Breaker-and Breaker-and-a-half -a-half scheme scheme.
(1) The breaker-and-a breaker-and-a-hal -halff arrangeme arrangement, nt, Figure 5-1c, provid provides es for two main main buses, buses, both both normal normally ly energi energized zed.. Betw Betwee een n the the buse busess are are thre threee circ circui uitt brea breake kers rs and and two two circui circuits. ts. This This arrang arrangeme ement nt allows allows for breake breakerr mainte mainte-nance nance without without interrup interruptio tion n of service. service. A fault fault on either either bus will cause cause no circuit circuit interrup interruptio tion. n. A breake breakerr failur failuree result resultss in the loss of two circuit circuitss if a common common breaker breaker fails and only one circuit if an outside breaker fails. (2) The advantages advantages of the breaker-andbreaker-and-a-hal a-halff scheme include: (a) High reliabilit reliability y and operationa operationall flexibili flexibility. ty. (b) (b) Capa Capabi bili lity ty of isol isolat atin ing g any any circ circui uitt brea breake kerr or eith either er main main bus bus for for main mainte tena nanc ncee with withou outt serv servic icee interruption. Figure Figure 5-1. Switchyard Switchyard bus arrangements arrangements
d. Ring Ring bus sche scheme me.
(1) (1) The The ring ring bus, Figure Figure 5-1b 5-1b,, cons consis ists ts of a loop loop of bus work with with each each bus section section separa separated ted by a breake breaker. r. Only Only limite limited d bus sectio sections ns and circui circuits ts can be remove removed d from from servi service ce in the the even eventt of a line line or bus bus faul fault. t. A line line fault results in the loss of the breakers on each side of the line, while a breaker failure will result in the removal of two bus sections sections from service. service. The ring bus arrangemen arrangementt allows allows for circuit circuit breaker breaker maintenanc maintenancee without without interrupinterruption of service to any circuit. (2) The advantages advantages of the ring bus scheme scheme include: include: (a) Low cost (one breaker breaker per line section section). ). (b) High reliabilit reliability y and operational operational flexibilit flexibility. y. (c) (c) Cont Contin inui uity ty of serv servic icee duri during ng brea breake kerr and and bus bus maintenance.
5-2
(c) A bus fault does not interrup interruptt service. service. (d) Double Double feed to each each circuit. circuit. (e) All switching switching can be done with circuit circuit breakers breakers.. (3) The disadvant disadvantages ages include: include: (a) Added cost cost of one half breaker breaker for each circuit. circuit. (b) (b) Prot Proteecti ction complex.
and and
con control trol
sche schem mes
are are
mor more
f. Double bus-double breaker scheme.
(1) (1) The The doub double le busbus-do doub uble le brea breake kerr arra arrang ngem emen ent, t, Figure Figure 5-1d, 5-1d, consis consists ts of two main main buses, buses, both both normal normally ly energized. energized. Between Between the main buses are two breaker breakerss and one circuit circuit.. This This arrang arrangeme ement nt allows allows for any breake breakerr to be removed from service without interruption to service to its circui circuit. t. A fault on either either main bus will cause cause no circuit cuit outage outage.. A breake breakerr failur failuree will result result in the loss of only one circuit.
EM 1110-2-3006 30 Jun 94 (2) The advantages advantages of the double double bus-double bus-double breaker scheme include:
(2) Structura Structurall considerat considerations ions including including ice and wind loading, short-circuit forces, and seismic loads.
(a) Very high reliability reliability and operationa operationall flexibility. flexibility.
The spacing spacing of bus supports supports should should limit limit bus sag under under maximum loading to not greater than the diameter of the bus, bus, or 1/150t 1/150th h of the span span length. length. IEEE IEEE 605 provides provides further further informati information on on substatio substation n electrical electrical,, mechanica mechanical, l, and structural design considerations.
(b) Any breaker breaker or either either bus can be isolat isolated ed without without service interruption. (c) A bus fault does not interrup interruptt service. service.
5-5. Switchyard Switchyard Materia Materials ls (d) There is a double double feed to each each circuit. circuit. (e) All switching switching is done with circuit circuit breakers. breakers. (f) Only one circuit circuit is lost if a breaker breaker fails. (3) The disadvan disadvantag tages es includ includee the high cost cost of two breakers per circuit. g. Recomme Recommende nded d scheme scheme.
The The break breaker er-a -and nd-a -a-h -hal alf f scheme scheme is genera generally lly recomm recommend ended, ed, as it provid provides es flexiflexibility bility and a reason reasonabl ably y simple simple method method of provid providing ing full full relay protection protection under emergency emergency switching switching condition conditions. s. The number of sections (line “bays”) needed is dependent on the the numb number er of tran transm smis issi sion on line liness and and gene genera rati tion on source sourcess coming coming into the substa substatio tion. n. The breake breaker-a r-andnd-aahalf scheme is normally designed and operated as a ring bus bus unti untill syst system em requ requir irem emen ents ts dict dictat atee more more than than six six breakers and six lines.
5-4. Bus Structures Structures a. Arrangemen Arrangements ts. The flat flat or low profi profile le type type of bus
construct construction ion with pedestal-s pedestal-suppor upported ted rigid rigid buses and Aframe line towers is ordinarily the most economical where space space and topogr topograph aphy y are favorab favorable. le. Conges Congested ted areas areas may require the use of a high, narrow steel structure and the use of short wire bus connections between disconnecting switche switchess and the buses. buses. Switch Switchyar yard d layout layoutss should should provid providee adequa adequate te access access for safe safe moveme movement nt of mainte mainte-nance equipment and the moving of future circuit breakers or other other major major items items of equipm equipment ent into into positi position on withou withoutt de-ene de-energi rgizin zing g primar primary y buses. buses. Cleara Clearance ncess to energi energized zed parts should, as a minimum, comply with ANSI C2, Section 12. Equipment Equipment access access requiremen requirements ts should be based on the remova removall of high-v high-volt oltage age bushin bushings, gs, arrest arresters ers,, and conservators and radiators from large power transformers. b. Bus design design criter criteria ia.
The The desi design gn of of rigi rigid d bus bus syssystems is influenced by the following criteria: (1) Electric Electrical al consid considera eratio tions ns includ including ing corona corona and ampacity limitations.
a. Genera Generall. After After design design drawin drawings gs showin showing g a gengeneral eral layo layout ut of the the swit switch chya yard rd and and deta detail ilss of elec electr tric ical al interconnections have been prepared, a drawing should be made up to accompany the specifications for the purchase of the the stru struct ctur ures es.. This This draw drawin ing g shou should ld show show the the size size,, spacing, and location of principal members and the loadings ings impose imposed d by electr electrica icall equipm equipment ent and lines. lines. Design Design load load assu assump mpti tion onss for for bus bus stru struct ctur ures es are are desc descri ribe bed d in EM 1110-2-3001. b. Structure Structure materials materials. The follo followin wing g are four types types of material most commonly used for substation structures:
(1) Steel. Steel. Steel is is the most most commonly commonly used used material. material. Its availability and good structural characteristics make it economica economically lly attractive attractive.. Steel, Steel, however, must have have adequate corrosion protection such as galvanizing or painting. Due to the maintenance maintenance associated associated with painting, painting, galvagalvanizing nizing is genera generally lly preferr preferred. ed. Galvan Galvanize ized d steel steel has an excell excellent ent servic servicee record record in enviro environme nments nts where where the pH leve levell is in the the rang rangee of 5.4 5.4 thro throug ugh h 9.6 9.6 (i.e. (i.e.,, a slig slight htly ly alkaline alkaline environment environment). ). Most industrial industrial environmen environments ts are in this pH range leading to the widespread use and excellent service service record of galvanized galvanized steel structure structures. s. Because Because of the unbrok unbroken en protec protectiv tivee finish finish requir required, ed, struct structure uress should not be designed to require field welding or drilling. Adequate information to locate mounting holes, brackets, and other devices devices must must be provid provided ed to the fabric fabricato atorr to allow all detail work to be completed before the protective finish is applied to the steel part. (2) Alumi Aluminum num.. In environ environmen ments ts where where the pH level level is below below 5.4 (i.e. (i.e. an acidic acidic environm environment ent,, such such as condiconditions existing in a brine mist), galvanized structures would give give poor poor servic service. e. In these these enviro environme nments nts,, consid considera eratio tion n should should be given given to struct structure uress fabric fabricate ated d with with alumi aluminum num members. members. Aluminum Aluminum structur structures es are satisfactory satisfactory at other locations, if the installed cost is comparable to the cost of the equiva equivalen lentt design design using using galvan galvanize ized d steel steel member members. s. Structures designed for aluminum are constructed of Alloy 6061-T6 6061-T6 and should be designed, designed, fabricated, fabricated, and erected erected
5-3
EM 1110-2-3006 30 Jun 94 in accordance with the Aluminum Association’s specifications for aluminum structures. (3) Concre Concrete. te. Pre-ca Pre-cast, st, pre-stre pre-stresse ssed d concre concrete te strucstructures tures may be econom economica icall in some some applic applicati ations ons such such as pull-off pull-off poles and switch structur structures. es. Care should should be taken taken to avoid the use of detrimental additives, such as calcium chlori chloride, de, to the concret concretee used used in the structur structures. es. Due to the larger larger struct structura urall sizes sizes and weight weightss involv involved, ed, specia speciall equipment may be required for concrete erection. (4) Wood. Wood. Wood Wood pole and timber timber struc structur tures es may be econom economica icall for tempor temporary ary struct structure uress or simple simple switch switch stru struct ctur ures es.. Wo Wood od memb member erss must must be trea treate ted d with with an approp appropria riate te preser preservat vative ive.. Struct Structura urall proper propertie tiess and size size tolera tolerance ncess of wood wood are variable variable and must must be consid considere ered d during the design process. c. Bus mate materia rials ls. The materia materials ls most common commonly ly used
for rigid rigid and wire bus are aluminu aluminum m and copper copper.. Rigid Rigid bus fittin fittings gs should should be limite limited d to bolted bolted connec connectio tions ns for copper copper,, and welded welded connecti connections ons on alumin aluminum. um. Bus fittings tings for alumi aluminum num wire wire should should be compre compressi ssion on type. type. Either Either bolted bolted or compre compressi ssion on fittin fittings gs are accept acceptabl ablee for use with copper wire bus.
5-6. Transformer Transformer Leads a. High-voltage High-voltage terminal connections connections.
The The co connec nnec-tions tions betwee between n the high-v high-volt oltage age termin terminals als of the transtransformer and the disconnect switch (or breaker) will usually be made with bare overhead conductors when the transformer former is locate located d in the switch switchyar yard. d. Howeve However, r, in cases cases where the transformer is in line with the axis of the disconnect, the connection between the disconnect terminals and the high-voltage bushing terminals can be made with suitably supported and formed rigid bus of the same type used in the rest of the switchyar switchyard. d. The fittings fittings and interinterconnection systems between the high-voltage bus and the disconnect disconnect switches should be designed designed to accommoda accommodate te cond condit itio ions ns of frequ requen entt load oad cycl cyclin ing g and and mini minim mal maintenance. b. Overhead Overhead conductors conductors.
Bare Bare overhea overhead d conduc conductor torss from the transmission line termination to the high-voltage bushings can occasionally be used when the transformers are installed at the powerhouse, and overhead lines to the switch switchyar yard d are used. used. An example example of this this would be when when the transmission line is dead-ended to the face of the dam, and the transformer is located at the base of the dam near its face, face, and behind behind the powerhou powerhouse. se. Howeve However, r, locati locating ng the transf transform ormers ers at the powerh powerhous ousee usuall usually y requir requires es the use of high-voltage bus to the line termination when the
5-4
line line is term termin inat ated ed on a dead dead-e -end nd stru struct ctur uree near near the the transformer. c. Test Test termina terminals ls.
To provi provide de a safe and and accura accurate te method method of transform transformer er dielectri dielectricc testing, testing, accommodat accommodations ions should should be made for easily easily isolating isolating transformer transformer bushings bushings from from the bus work. Double Double test termina terminals ls should should be provided on transformer high-voltage and neutral bushings in accordance accordance with Corps Corps of Engineers Engineers practice practice.. The design should should provide provide adequate adequate clearance clearance from energized energized lines for personnel conducting the tests.
5-7. Powerhouse Powerhouse - Switchyard Switchyard Power Control Control and Signal Leads a. Cable Cable tunn tunnel el.
(1) A tunnel tunnel for power and control control cables cables should should be provided provided between the powerhouse and switchyar switchyard d whenever ever practi practical cal.. Use of a tunnel tunnel provide providess ready ready access access to the cables, provides for easy maintenance and expansion, and offers offers the easies easiestt access access for inspec inspectio tion. n. This This tunnel tunnel should extend practically the full length of the switchyard for access to all of the switchyard equipment. (2) The control control and data (non-s (non-sign ignal) al) cables cables should should be carrie carried d in trays trays in the tunnel, tunnel, and contin continued ued in steel steel conduits from the trays to circuit breakers and other controlle trolled d equipm equipment ent so as to elimi eliminat natee the need for manhole holess and and hand handho hole les. s. If there there is a cont contro roll hous housee in the swit switch chya yard rd,, it shou should ld be situ situat ated ed over over the the tunn tunnel el.. The The tunnel should be lighted and ventilated and provided with suitable drains, or sumps and pumps. (3) If the generato generatorr leads, leads, transf transform ormer er leads, leads, or stastation service feeders are located in the tunnel, the amount of heat heat dissip dissipate ated d should should be calcul calculate ated d and taken taken into into considerat consideration ion in providing providing tunnel ventilation ventilation.. The power cables should be carefully segregated from the control and data acquisition cables to prevent electromagnetic interference, and to protect the other cables from damage resulting from from power cable cable faults. faults. If the tunnel tunnel lies below below a possib possible le high-w high-wate aterr elevat elevation ion,, it should should be design designed ed to withstand uplift pressures. (4) (4) Sign Signal al cabl cables es shou should ld be phys physic ical ally ly sepa separa rate ted d from from power power and contro controll circui circuits. ts. If practica practical, l, the signal signal cable should be placed in cable trays separate from those used for either either control control or power cables. cables. In no case should sign signal al cabl cables es be run run in cond condui uitt with with eith either er cont contro roll or powe powerr cabl cables es.. The The phys physic ical al sepa separa rati tion on is inte intend nded ed to reduce reduce the coupling coupling of electromag electromagneti neticc interfere interference nce into the signal signal cable cable from from pulses pulses in the (usual (usually ly unshie unshielde lded) d)
EM 1110-2-3006 30 Jun 94 contro controll cables cables,, or power power system system freque frequency ncy energy energy from from powe powerr cabl cables es.. Even Even thou though gh the the sign signal al cabl cablee will will be shielded, shielded, commercia commercially lly available available shielding shielding does not provide vide 100 percen percentt covera coverage ge or perfec perfectt shield shielding ing,, and the separa separatio tion n is needed needed to reduce reduce electr electrica icall noise noise supersuperimposed on the signal. b. Duct Duct line line. For small small installati installations ons having having a limited limited
amount of transforming and switching equipment, it may be desirable and economical to use duct lines instead of a cabl cablee tunn tunnel el for cont contro roll and and powe powerr cabl cables es.. The The duct duct system system should should use concrete concrete encased encased nonmetall nonmetallic ic conduit, conduit, and manholes or handholes of adequate number and size should should be provid provided. ed. Separa Separate te ducts ducts for the power power cables cables and and the the cont contro roll and and data data acqu acquis isit itio ion n cabl cables es shou should ld be provided. provided. At least 30 percent percent spare duct capacity capacity should should be provided for power cables, and 50 percent spare capacity provided provided for control control and data acquisition acquisition cables. cables. The manhol manholes es should should be design designed ed to drain drain unless unless costs costs are prohibitive. c. High-v High-volta oltage ge bus.
(1) Genera General. l. There There are three catego categorie riess of high-vol high-volttage connection systems that find application in hydroelectric installa installations tions requiring requiring high-volt high-voltage age interconne interconnection ction between the power plant and the switchyard or utility grid interconne interconnection ction.. These are as follows: follows: (a) (a) Oil Oil or SF6 gas-insulated cable with paper-insulated conduc conductor tors. s. Cables Cables commonl commonly y used used for circuit circuitss above above 69 kV consist of paper-insulated conductors pulled into a welded steel pipeline, which is filled with insulating oil or inert inert gas. The oil or gas in the pipe type constr construct uction ion is usuall usually y kept kept under under about 200 psi pressur pressure. e. These These cables cables can safely safely be instal installed led in the same tunnel tunnel between between the powerh powerhous ousee and the switch switchyar yard d that that is used used for contro controll cables. (b) Solid Solid dielectricdielectric-insul insulated ated cable. cable. Solid dielect dielectricricinsu insula late ted d cabl cables es are are also also avai availa labl blee for for syst system emss abov abovee 69 kV . Their Their use may be consid considere ered, d, but carefu carefull evalua evalua-tion of their reliability and performance record should be made made.. They They offe offerr adva advant ntag ages es of ease ease of inst instal alla lati tion on,, eliminati elimination on of oil or gas system system maintenan maintenance, ce, and lower cost. Their electrica electricall character characteristi istics cs should be considered considered in fault studies and stability studies. (c) (c) SF6 gas-i gas-insu nsulat lated ed bus. An example example of a typica typicall instal installat lation ion is an underg undergrou round nd power power plant plant with with a unit unit switching scheme and the GSU transformer located underground ground in the plant. plant. A high-v high-volt oltage age interco interconne nnecti ction on is
requ requir ired ed thro throug ugh h a cabl cablee shaf shaftt or tunn tunnel el to an abov aboveeground on-site switchyard. (2) Direct Direct burial burial.. While While insulat insulated ed cable cable of the type type descri described bed can be direct directly ly buried buried,, the practi practice ce is not recrecommended for hydroelectric plants because the incremental cost of a tunnel normally provided for control circuits and pipeli pipelines nes is moderat moderate. e. In case of oil leaks or cable cable failur failure, e, the access accessibi ibilit lity y of the cable cable pipes pipes in the tunnel tunnel will will speed speed repair repairss and could could avoid avoid consid considera erable ble loss loss in revenu revenue. e. Space Space for the locatio location n of cable termina terminall equipequipment should be carefully planned. (3) (3) Buri Burial al tren trench ch.. If the the powe powerr cabl cables es from from the the powerhouse to the switchyard must be buried directly in the earth, earth, the burial burial trench trench must be in accord accordanc ancee with with safety safety requireme requirements, nts, provide a firm, firm, conformin conforming g base to lay the cable cable on, and provide provide protec protectio tion n over over the cable. cable. The The cabl cablee must must have have an over overal alll shie shield ld,, whic which h must must be well-grounded, to protect, so far as possible, people who might accidently penetrate the cable while digging in the burial area. (4) (4) SF6 gasgas-in insu sula late ted d syst system ems. s. SF6 gas-insulated systems offer the possibility of insulated bus and complete high-v high-volt oltage age switch switchyar yard d system systemss in a compac compactt space. space. Gas-insulated substation systems should be considered for underg undergrou round nd power power plant plant instal installat lation ionss or any situat situation ion requir requiring ing a substa substatio tion n system system in an extrem extremely ely confin confined ed spac space. e. The The desi design gn shou should ld acco accomm mmod odat atee the the need need for for disassembly of each part of the system for maintenance or repair repair.. The designe designerr should should also conside considerr that that the gas is inert, inert, and in a confin confined ed space space will will displa displace ce oxygen oxygen and caus causee suff suffoc ocat atio ion. n. Afte Afterr expo exposu sure re to arci arcing ng,, SF 6 gas contains hazardous byproducts and special precautions are needed for evacuating the gas and making the equipment safe safe for normal normal maint mainten enan ance ce work. work. SF6 gas pressure pressure varies with temperature and will condense at low ambient temper temperatu atures res.. When When SF6 equipm equipment ent is expose exposed d to low temper temperatu atures res,, heatin heating g must must be provid provided. ed. The manufacmanufacture turer’ r’ss reco recomm mmen enda dati tion onss must must be foll follow owed ed.. IEEE IEEE C37.123 provides guidance on application criteria for gas insulated substation systems.
5-8. Circuit Breakers Breakers a. Interru Interruptin pting g capaci capacity ty.
The requi required red inter interrup ruptin ting g rating of the circuit breakers is determined by short-circuit fault fault studies. studies. (See Chapter Chapter 2.) 2.) In conducting conducting the the studies, studies, conservative allowances should be made to accommodate ultimate ultimate system system growth. If information information of system system capacity and characteristics is lacking, an infinite bus at the end
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EM 1110-2-3006 30 Jun 94 of the the tran transm smis issi sion on inte interc rcon onne nect ctio ion n can can be assu assume med. d. Using an infinite bus will result in conservative values of fault kVA to be interrupted, and will probably not unduly influence influence the final final result. ANSI C37.06 provides provides perforperformance parameters of standard high-voltage breakers. b. Design consideratio considerations. ns.
(1) (1) Brea Breake kers rs for for 69 kV and above above genera generally lly are SF6 gas-in gas-insul sulate ated, d, with with the dead dead tank tank design design prefer preferred red for seismi seismicc consid considera eratio tions. ns. The details details of the relaying relaying will determine the number of CTs required, but two CTs per pole pole should should general generally ly be the minimu minimum. m. Three Three CTs may be required for the more complex switching arrangements, such as the breaker-and-a-half scheme. (2) (2) At 230 230 kV and and above, two trip coils are preferred. The integr integrity ity of the trippi tripping ng circui circuit(s t(s)) should should be monimonitore tored d and and if remo remote tely ly cont contro roll lled ed,, the the stat status us shou should ld be teleme telemeter tered ed to the control control point. point. The gas system system of SF 6 breakers should be monitored since loss of SF 6 gas or low gas pressure blocks breaker operation. (3) Breaker Breaker auxiliary auxiliary “a” and “b” switch contacts contacts are used used extens extensive ively ly to initia initiate te and block block the operat operation ion of back backup up rela relayi ying ng sche scheme mes. s. As brea breake kers rs are are adde added, d, and and protection added to cover new system contingencies, the prot protec ecti tive ve rela relay y sche scheme mess beco become me more more comp comple lex. x. To accomm accommoda odate te these these situat situation ions, s, breake breakers rs should should be purpurchased with at least eight “a” and eight “b” spare auxiliary contacts. (4) Layout Layout of the substa substatio tion n should should consid consider er access access required for maintenance equipment, as well as horizontal and vertic vertical al electr electrica icall cleara clearance nce for the switch switches es in all normal operating positions. (5) Specifica Specifications tions prepared prepared for outdoor application applicationss of SF6 power circui circuitt breake breakers rs should should provid providee the expect expected ed ambient operating temperature ranges so the breaker manufacturer ufacturer can provide provide adequate adequate heating to ensure ensure proper proper operat operation ion of the breake breakerr throug through h the ambien ambientt operat operating ing rang range. e. Mini Minimu mum m stan standa dard rd oper operat atin ing g ambi ambien entt for for SF 6 equipment is -30 °C (IEEE Standard C37.122).
5-9. Disconnect Disconnect Switches Switches a. Disconnect Disconnect operators operators.
Manual Manual or motor motor-op -opera erated ted gang-operated disconnect switches should be provided for isolat isolating ing all circui circuitt breake breakers. rs. For operatin operating g voltag voltages es of 230 kV or greater, or for remotely operated disconnects, disconnects, the disconnect disconnectss should be motor operated. operated. In some cases, depending on the switching scheme and substation layout,
5-6
one or both of the buses will be sectionalized by disconnects. nects. The section sectionali alizin zing g discon disconnec nectt switch switches es may be either manual or motor-operated, depending on their voltage rating rating and the require requiremen ments ts of statio station n design design.. The manual manual operat operating ing mechan mechanism ism for heavy, heavy, high-v high-volt oltage age disconnects should preferably be of the worm gear, crankoperated type. b. Remote Remotely ly operat operated ed discon disconnec nects ts. Remo Remote tely ly ope operrated disconnect disconnect switches switches should be installed installed only as line or breaker breaker disconne disconnects cts.. Use of a remote remotely ly operated operated disconnect switch to serve as generator disconnect is strongly discourage discouraged. d. Operation Operation of generator generator disconnects disconnects should should require require visual visual verificat verification ion (through (through operator operator presence) presence) of the open position and a lockable open position to prevent the possibility of misoperation or misindication by reconnecting an out-of-service generator to an energized line. c. Discon Disconnec nectt featur features es. All All disc discon onne nect ct swit switch ches es should should be equipp equipped ed with arcing arcing horns. horns. The disconn disconnect ect switch on the line side of the line circuit breakers should be equipp equipped ed with with ground grounding ing blades blades and mechan mechanica ically lly interl interlock ocked ed operati operating ng gear. gear. At 230 kV and above, above, line line and generator disconnect switches should be of the rotating insulator, vertical break type, with medium- or highpressure pressure contacts. contacts. Circuit Circuit breaker isolation isolation switches switches may be either either a two-in two-insul sulato atorr “V” or a side side break break type. type. Both Both the contac contacts ts and the blade blade hinge hinge mechan mechanism ism should should be designed designed and tested tested to operate operate satisfact satisfactorily orily under severe severe ice ice cond condit itio ions ns.. At 345 345 kV and and 500 500 kV , vertic vertical al break break discon disconnec nects ts are prefer preferred red since since they they allow allow for reduce reduced d phase spacing and installation of surge suppression resistors tors.. Each Each swit switch ch pole pole should should have have a sepa separa rate te motor motor operator.
5-10. Surge Arresters Arresters a. Prefer Preferred red arrester arrester types types .
Surge Surge arres arrester terss should should be of the station type (preferably a metal oxide type) that provid provides es the greate greatest st protec protectiv tivee margin marginss to genera generatin ting g station equipment. b. Arrest Arrester er locatio location n.
Arre Arrest ster erss shou should ld be locat located ed immediate immediately ly adjacent adjacent to the transform transformers, ers, if the connecconnection between the transformers and switching equipment is made by overhead overhead lines. lines. If high-volta high-voltage ge cable is used for this connection, connection, the arresters arresters should be placed placed both near the switchyard terminals of the cable and adjacent to the transf transform ormer er termin terminals als.. Arrest Arrester er connec connectio tions ns should should be designed to accommodate removal of the arrester without removi removing ng the main main bus connec connectio tion n to the high-v high-volt oltage age bushin bushing. g. Locati Location on of arrest arresters ers should should be in accord accordanc ancee with IEEE C62.2.
EM 1110-2-3006 30 Jun 94 c. Arrest Arrester er protec protection tion.
In all all case cases, s, enou enough gh spac spacee should be allowed between arresters and other equipment to prevent prevent damage if the arresters arresters should should fail. If arresters arresters are located where they form a hazard to operating personnel, they should should be suitably suitably enclosed. enclosed. This can generally generally be accomplished with a woven wire fence provided with a lockab lockable le gate. gate. The design design of the enclos enclosure ure should should consider the clearance requirements for the switchyard operating voltage. d. Arrest Arrester er voltage voltage rating rating. The The voltag voltagee rating rating of the
arresters should be selected to provide a reasonable margin between the breakdown voltage of the arrester and the basic basic impuls impulsee insula insulatio tion n level level (BIL) (BIL) of the equipm equipment ent protected protected.. The rating, rating, in the majority majority of cases, should be the lowest satisfactory voltage for the system to which the arresters are connected. e. Grounded-ne Grounded-neutral utral arrester arresterss.
(1) In applyi applying ng ground groundeded-neu neutra trall rated rated arrest arresters ers,, the designer should consider whether, under all conditions of operation, the system characteristics will permit their use. Grounded-neutral arresters should not be used unless one of the following conditions will exist: (a) The system system neutral neutral will be connec connected ted to the system tem grou ground nd thro throug ugh h a copp copper er grou ground ndin ing g cond conduc ucto torr of adequate size (solidly grounded) at every source of supply of short-circuit current.
(b) (b) The The syst system em neut neutra rall is soli solidl dly y grou ground nded ed or is ground grounded ed throug through h reacto reactors rs at a suffic sufficien ientt number number of the source sourcess of supply supply of shortshort-cir circui cuitt curren currentt so the ratio ratio of the fundamental-frequency zero-sequence reactance, X o, to the positive positive sequence reactance, reactance, X 1, as viewed from the poin pointt of faul fault, t, lies lies betw betwee een n valu values es of 0 and and 3.0 3.0 for for a ground ground fault fault to any location location in the system, system, and for any condit condition ion of operat operation ion.. The ratio ratio of the zero-s zero-sequ equenc encee resistanc resistance, e, Ro, to the positi positive ve sequen sequence ce reacta reactance nce,, X 1, as viewed from the ground fault at any location, should be less than 1.0. The arrester arrester should have suitable suitable charactercharacteristics istics so that that it will will not discha discharge rge during during voltag voltagee rises rises caused by switching surges or fault conditions. (2) Consid Considera eratio tion n should should be given given to the protec protectio tion n of tran transm smis issi sion on line line equi equipm pmen entt that that may may be loca locate ted d between between the arrester arresterss and the incoming incoming transmiss transmission ion line entran entrance ce to the substat substation ion.. In cases where where the amount amount of equipm equipment ent is extens extensive ive or the distan distance ce is substa substanti ntial, al, it will probably be desirable to provide additional protection on the incoming transmission line, such as spark gaps or arresters. (3) If the statio station n transf transform ormers ers are constr construct ucted ed with with the high-v high-volt oltage age neutra neutrall connec connectio tion n termin terminate ated d on an external (H 0) bushin bushing, g, a surge surge arrest arrester er should should be applie applied d to the bushing.
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EM 1110-2-3006 30 Jun 94
Chapter 6 Generator-Voltag Generator-Voltage e System
6-1. 6-1. Genera Generall The genera generator tor-vo -volta ltage ge system system descri described bed in this this chapte chapterr includes includes the leads leads and associate associated d equipment equipment between the generator generator terminals terminals and the low-voltag low-voltagee terminals terminals of the GSU transf transform ormers ers,, and betwee between n the neutra neutrall leads leads of the gene genera rato torr and and the the powe powerr plan plantt grou ground ndin ing g syst system em.. The The equipment generally associated with the generator-voltage system system includes includes switchgear switchgear;; instrumen instrumentt transform transformers ers for meteri metering, ng, relayi relaying, ng, and genera generator tor excita excitatio tion n system systems; s; neutral grounding equipment; and surge protection equipment. ment. The equipme equipment nt is classi classifie fied d as medium-v medium-volt oltage age equipment.
6-2. Generator Generator Leads a. Genera Generall. The term “generat “generator or leads” applies applies to the
circui circuits ts betwee between n the genera generator tor termi terminal nalss and the lowlowvoltag voltagee termin terminals als of the GSU transf transform ormers ers.. The equipequipment ment sele select cted ed depe depend ndss upon upon the the dist distan ance ce betw betwee een n the the generator generator and transform transformer, er, the capacity of the generator, generator, the type of generator breakers employed, and the economics of the instal installat lation ion.. There There are two genera generall classe classess of generator generator leads: those consisting consisting of metal-enclose metal-enclosed d buses and those consisti consisting ng of medium-volta medium-voltage ge cables. The two classe classes, s, their their advant advantage ages, s, disadv disadvant antage ages, s, and select selection ion criteria are discussed in the following subparagraphs. b. Metal-e Metal-encl nclose osed d buses buses.
There There are thre threee categor categories ies of metal-enc metal-enclose losed d bus: nonsegrega nonsegregated-p ted-phase, hase, segregatedsegregatedphase, phase, and isolatedisolated-phase phase.. Each type has specific specific application tionss depe depend nden entt main mainly ly on curr curren entt rati rating ng and and type type of circuit breaker employed with the bus. (1) Nonsegrega Nonsegregated-p ted-phase hase buses. buses. All phase phase conductor conductorss are enclosed in a common metal enclosure without barriers, with phase conductors insulated with molded material and supported on molded material or porcelain insulators. This This bus arrang arrangeme ement nt is normal normally ly used used with with metalmetal-cla clad d swit switch chge gear ar and and is avai availa labl blee in rati rating ngss up to 4,00 4,000 0A (6,00 ,000 A in 15-kV applica applicatio tions) ns) in medium medium-vo -volta ltage ge switchgear applications. (2) Segregated Segregated-phas -phasee buses. buses. All phase phase conductor conductorss are enclos enclosed ed in a common common enclos enclosure ure,, but are segreg segregate ated d by metal metal barriers barriers between phases. phases. Conductor Conductor supports supports usually are of porcelain. porcelain. This bus arrangemen arrangementt is available in the same same voltag voltagee and curren currentt rating ratingss as nonseg nonsegreg regate ateddphase bus, but finds finds applicati application on where space limitati limitations ons
preven preventt the use of isolat isolateded-pha phase se bus or where where higher higher moment momentary ary curren currentt rating ratingss than than those those provid provided ed by the nonsegregated phase are required. (3) Isolat Isolateded-pha phase se buses. buses. Each Each phase phase conduct conductor or is enclos enclosed ed by an indivi individua duall metal metal housin housing, g, which which is sepaseparated rated from from adjace adjacent nt conduc conductor tor housin housings gs by an air space. space. Conductor Conductor supports supports are usually of porcelain. porcelain. Bus systems systems are available in both continuous and noncontinuous housing design. design. Contin Continuou uouss design designss provid providee an electr electrica ically lly continuous housing, thereby controlling external magnetic flux. flux. Noncontinu Noncontinuous ous designs designs provide provide external external magnetic magnetic flux flux contro controll by insula insulatin ting g adjace adjacent nt sectio sections, ns, provid providing ing grounding at one point only for each section of the bus, and by provid providing ing shorti shorting ng bands bands on extern external al suppor supportin ting g steel steel structures structures.. Noncontinu Noncontinuous ous designs can be considered considered if installation of the bus will be at a location where competent petent field welders welders are not available. available. However, However, continucontinuous housing bus is recommended because of the difficulty in maintainin maintaining g insulation insulation integrity integrity of the noncontinu noncontinuous ous housing housing design during its service service life. IsolatedIsolated-phase phase bus is available in ratings through 24,000 A and is associated with with instal installat lation ionss using using statio station n cubicl cubiclee switch switchgea gearr (see (see discussion in paragraph 6-7 b). c. Metal-enclosed Metal-enclosed bus applicatio application n criteria.
(1) (1) For For most most main main unit unit appl applic icat atio ions ns,, the the meta metallenclosed form of generator leads is usually preferred, with prefer preferenc encee for the isolat isolateded-pha phase se type type for rating ratingss above above 3,000 A. Enclosed Enclosed buses that that pass through through walls or floors should be arranged so as to permit the removal of housings to inspect or replace insulators. (2) On isolated-phas isolated-phasee bus runs (termed (termed “delta bus”) from the generators to a bank of single-phase GSU transform former ers, s, layo layout utss shou should ld be arra arrang nged ed to use use the the most most econom economica icall combin combinati ation on of bus rating ratingss and length lengthss of single single-ph -phase ase bus runs. runs. The runs (“risers (“risers”) ”) to the single single-phase phase transf transform ormers ers should should be sized sized to carry carry the curren currentt corr corres espo pond ndin ing g to the the maxi maximu mum m kVA rati rating ng of the transformer. (3) (3) Meta Metall-en encl clos osed ed bus bus conn connec ecti tion onss to the the GSU GSU transformer that must be supported at the point of connection to the transformer should have accommodations permitt mittin ing g the the bus bus to be easi easily ly disc discon onne nect cted ed shou should ld the the transf transform ormer er be remove removed d from from servic service. e. The bus design design should should incorpora incorporate te weather-t weather-tight ight closures at the point of disconnection to prevent moisture from entering the interior of the bus housing.
6-1
EM 1110-2-3006 30 Jun 94 (4) (4) On all all encl enclos osed ed bus bus runs runs,, requ requir irem emen ents ts for for enclos enclosing ing the connec connectio tions ns betwee between n the bus and the lowlowvoltage bushings of the GSU transformer should be coordinated dinated and responsib responsibilit ilities ies for scopes scopes of supply supply clearly clearly define defined d betwee between n transf transform ormer er suppli supplier er and bus suppli supplier. er. Details of the proposed design of the connector between the GSU transformer bushing terminals and the bus terminal should be evaluated evaluated to ensure ensure probabilit probability y of reliable service life of the connection system. d. Insulated Insulated cables. cables.
(1) Cables Cables may be appropriat appropriatee for some small generagenerators tors or in inst instal alla lati tion onss wher wheree the the GSU tran transf sfor orme merr is locate located d in the plant’ plant’ss switch switchyar yard. d. In the latter latter situat situation ion,, econom economic ic and techni technical cal evalua evaluatio tions ns should should be made made to determine the most practical and cost-effective method to make make the interco interconne nnecti ction. on. Cables Cables,, if used, used, should should have copper copper conductors. conductors. Acceptable Acceptable cable types include: include:
requ requir irem emen ents ts dete determ rmin inee wheth whether er the the mach machin inee is to be solidl solidly y ground grounded ed throug through h a circui circuitt breake breakerr (usual (usually ly not possible), through a circuit breaker and reactor (or resistor), or through a disconnecting switch and a distribution type type of transfor transformer mer (See Chapter Chapter 3.) Solidl Solidly y ground grounded ed system systemss do not find find wide wide applic applicati ation on becaus becausee result resulting ing faul faultt curr curren ents ts init initia iate ted d by a stat stator or to grou ground nd faul faultt are are much higher than currents produced by alternative neutral grounding grounding systems. systems. Higher Higher ground fault fault currents currents lead to higher probability of damage to the stator laminations of the connect connected ed generato generator. r. If a circui circuitt breake breakerr is used used in the grounding scheme, it can be either a single-pole or a standard 3-pole air circuit breaker with poles paralleled to form a single-pole single-pole unit. Suitable Suitable metal enclosure enclosuress should be provided for the reactors, resistors, or grounding transformers used in the grounding system.
6-4. Instrument Instrument Transfor Transformers mers a. Genera Generall.
(a) Single Single conduct conductor, or, ethyle ethylenene-pro propyl pyleneene-rubb rubber er (EPR) insulated, with non-PVC jacket. (b) Multi-conductor, ethylene-propylene-ru ethylene-propylene-rubber bber (EPR) insulated cables, with aluminum or steel sheath, and nonPVC jacket, in multiple if necessary to obtain capacity. (c) Oil-pipe Oil-pipe cable cable systems. systems. (2) Oil-fi Oil-fille lled d cable cable termin terminati ations ons with with cables cables termiterminated nated with a conduc conductor tor lug and a stress stress cone should should be used for terminati terminating ng oil-pipe oil-pipe cable systems. systems. Cold shrink shrink termination kits should be used for terminating single and multimulti-con conduc ductor tor EPR cables cables.. Termin Terminati ation on device devicess and kits should meet the requirements of IEEE 48 for Class I terminations. (3) When When cables cables of any type type are run in a tunnel, tunnel, the effect of cable losses should be investigated to determine the safe safe curren current-c t-carr arryin ying g capaci capacity ty of the cable cable and the extent extent of tunnel tunnel ventilati ventilation on required required to dissipate dissipate the heat generated generated by these losses. losses. Locations Locations where hot spots spots may occu occur, r, such such as rise risers rs from from the the tunn tunnel el to equi equipm pmen entt or cond condui uitt exp exposed osed to the the sun sun, shou should ld be give given n full full consideration.
6-3. Neutral Neutral Grounding Grounding Equipment Equipment Equipm Equipment ent betwee between n the genera generator tor neutra neutrall and ground ground should, insofar as practicable, be procured along with the generator generator main leads leads and switchgear. switchgear. The conductor conductor may be either either metalmetal-enc enclos losed ed bus or insula insulated ted cable cable in nonnonmagnetic magnetic conduit. conduit. Generator Generator character characteristi istics cs and system
6-2
The instrum instrument ent transf transform ormers ers requir required ed for the unit control and protective relaying are included in procuremen procurements ts for metal-clad metal-clad switchgear switchgear breakers breakers that are to be employ employed ed for generat generator or switch switching ing.. The instrume instrument nt transform transformers ers are mounted mounted in the switchgear switchgear line-up line-up with potential transformers mounted in draw-out compartments for maintenance maintenance and service. service. Current Current transformer transformerss for the GSU transformer zone differential relay are also mounted in the metalmetal-cla clad d switch switchgea gearr cubicl cubicles. es. In isolat isolateded-pha phase se bus installations, the instrument transformers are included in procur procureme ement nt for the isolat isolateded-pha phase se bus. bus. The current current transformers, including those for generator differential and transform transformer er different differential ial protection protection,, are mounted mounted “in-line” “in-line” in the bus with terminations in external terminal compartments. ments. Requir Required ed potent potential ial transfor transformer merss are mounted mounted in dedica dedicated ted compar compartm tment entss tapped tapped off the main main bus leads. leads. The dedica dedicated ted compar compartm tment entss also also contai contain n the genera generator tor surge protection equipment (see Chapter 3, “Generators”). Specified accuracy classes for instrument transformers for either type of procurement should be coordinated with the requ requir irem emen ents ts of the the cont contro rol, l, prot protec ecti tive ve rela relayi ying ng,, and and metering metering systems. systems. Instrument Instrument transform transformers ers for the generator excitation system should be included in the appropriate procurement. b. Current Current transform transformers ers. Current Current transfor transformers mers of of the
mult multip iple le seco second ndar ary y type type are are usua usuall lly y requ requir ired ed and and are are mounte mounted d in the isolat isolateded-pha phase se bus or in the metalmetal-cla clad d switch switchgea gearr to obtain obtain the necess necessary ary second secondary ary circui circuits ts within within a reason reasonabl ablee space. space. Curren Currentt transf transform ormers ers in the neutral end of the generator windings are usually mounted in the the gene genera rato torr air air hous housin ing. g. Acce Access ssib ibil ilit ity y for for shor shorttcircuitin circuiting g the secondary secondary circuits circuits should should be considered considered in the equipment equipment layout. layout. The current current transformers transformers should should be
EM 1110-2-3006 30 Jun 94 designed designed to withstand withstand the momentary momentary currents currents and shortcircuit stresses for which the bus or switchgear is rated. c. Potential Potential transformer transformerss. The potenti potential al transfo transformer rmerss
for metering and for excitation system service are housed in separate separate compartments compartments of the metal-clad metal-clad switchgear. switchgear. If stat statio ion n cubi cubicl clee brea breake kers rs or isol isolat ated ed-p -pha hase se bus bus are are involved, a special cubicle for potential transformers and surge surge protec protectio tion n equipm equipment ent is provid provided ed in a variet variety y of arrang arrangeme ements nts to simpli simplify fy genera generator tor lead lead connec connectio tions. ns. Potent Potential ial transf transform ormers ers should should be protec protected ted by curren currenttlimiting limiting resistors resistors and fuses. Draw-out Draw-out type mountings mountings are standa standard rd equipm equipment ent in metalmetal-cla clad d switch switchgea gear. r. Simila Similarr arrang arrangeme ements nts are provid provided ed in cubicl cubicles es associ associate ated d with with isolated-p isolated-phase hase bus. Cubicles Cubicles with the isolated-pha isolated-phase se buses also provide phase isolation for transformers.
6-7. Circuit Breakers Breakers a. Genera Generall. The The par particu ticullar swit witchin ching g sche schem me sele select cted ed from from thos thosee desc descri ribe bed d in Chap Chapte terr 2, “Bas “Basic ic Switching Provisions,” the generator voltage and capacity rating rating,, and result resultss from from fault fault studie studiess will will determ determine ine the type type of genera generator tor breake breakerr used used for switch switching ing,, togeth together er with its continuous current rating and short-circuit current rati rating ng.. If a “uni “unit” t” swit switch chin ing g sche scheme me is chosen chosen with switching on the high side of the GSU transformer, then criteria criteria regarding regarding high-volta high-voltage ge power circuit circuit breakers breakers as described described in Chapter Chapter 5, “High-Volt “High-Voltage age System” are used to select select an approp appropria riate te breaker. breaker. If a genera generator tor-vo -volta ltage ge switching scheme is selected, then criteria outlined in this paragraph should be used for breaker selection. b. Generator-vol Generator-voltage tage circuit circuit breaker types types.
6-5. Single Unit Unit and Small Small Power Plant Plant Considerations When When metalmetal-cla clad d switch switchgea gearr is used used for genera generator torss in small small plants plants (havin (having g typica typically lly one or two genera generator torss of approximately 40,000 kW or less) the switchgear may be equipped equipped with indicatin indicating g instrumen instruments, ts, control control switches, switches, and other unit control control equipment equipment (e.g., annunciat annunciators ors and record recorders ers)) mounte mounted d on the switchg switchgear ear cell doors. doors. This This arrangement can take the place of a large portion of the convention conventional al control switchboar switchboard. d. The switchgear switchgear may be locate located d in a contro controll room, room, or the control control room room omitte omitted d entirely, entirely, depending depending upon the layout layout of the plant. Current Current phil philos osop ophy hy is to make make the the smal smalle lerr plan plants ts suit suitab able le for for unmann unmanned ed operat operation ion,, and remote remote or automa automatic tic contro control. l. This This sche scheme me elim elimin inat ates es the the need need for for a cont contro roll room room.. Arrang Arrangeme ements nts for contro controll equipm equipment ent with with this this type type of sche scheme me are are desc descri ribe bed d in more more deta detail il in Chap Chapte terr 8, “Control System.”
6-6. Excitation Excitation System System Power Potential Potential Transformer The power power potent potential ial transf transform ormer er (PPT) (PPT) is fed from from the generator generator leads as described described in paragraph paragraph 3-6 e(2), Chapter 3, “Generat “Generators ors.” .” The PPT is procur procured ed as part part of the excitation excitation system system equipment. equipment. The PPT should be a threethreephase, 60-Hz, self-cooled, ventilated dry type transformer. The PPT is genera generally lly tapped tapped at the generato generatorr bus with primary current limiting fuses, designed for floor mounting, and with a low-voltage terminal chamber with provisions for terminating the bus or cable from the excitation system power conversion equipment.
(1) (1) Wh When en gene genera rato torr-vo volt ltag agee circ circui uitt brea breake kers rs are are required, required, they are furnished furnished in factory-b factory-built uilt steel encloenclosures sures in one of three three types. types. Each Each type type of circui circuitt breaker breaker has specific applications dependent on current ratings and shortshort-cir circui cuitt curren currentt rating ratings. s. In genera general, l, Table Table 6-1 provides a broad overview of each breaker type and its range of applic applicati ation on for generato generatorr switch switching ing.. The three three types types are as follows: (a) Metal-c Metal-clad lad switch switchgea gear. r. MetalMetal-cla clad d switch switchgea gearr breakers can be used for generator switching on units of up to 45 MVA at 13.8 kV , depending on interrupting duty requ requir irem emen ents ts.. Deta Detail ilss of cons constr truc ucti tion on are are cove covere red d in Guide Specification for Civil Works Construction CWGS1634 16345. 5. Eith Either er vacu vacuum um inte interr rrup upte ters rs or SF6 interrupting mediums are permitted by the guide specification. (b) Stati Stationon-typ typee cubicl cubiclee switch switchgea gear. r. Statio Station-t n-type ype breakers breakers can be used in generator generator switching switching applicati applications ons on units of approximately 140 MVA. Detail Detailss of constr construcuction tion are cover covered ed in IEEE IEEE C37.2 C37.20. 0.2. 2. For For SF6 circuit breakers, breakers, the insulating insulating and arc-exting arc-extinguishi uishing ng medium medium is the gas. gas. For indoor indoor equipm equipment ent,, in areas areas not allowed allowed to reach temperatures at or near freezing, the gas will probably not require heating heating provisions. provisions. However, However, special care and handling is needed for SF 6 gas. (c) In-lin In-linee isolat isolateded-pha phase se bus breake breakers. rs. For highhighcurrent, current, medium-vo medium-voltage ltage,, generator generator breaker breaker applicati applications, ons, i.e. i.e.,, 15 kV , 6,00 6,000 0 Amp Amp or high higher er,, in-l in-lin inee brea breake kers rs moun mounte ted d in the the isol isolat ated ed-p -pha hase se bus bus syst system em have have been been empl employ oyed ed on high high-c -cap apac acit ity y syst system ems. s. Thes Thesee brea breake kers rs
6-3
EM 1110-2-3006 30 Jun 94 Table 6-1 Generator Breaker Application Table, 13.8- kV Application Application Upper Limit Generator Application MVA
Continuous Current Rating, kA
Short-Circuit Current Rating @ 13.8 kV
Breaker Type
45
3.0
40 kA
Draw Out
SF6 or vacuum
143
6.0
63 kA
Station Cubicle
SF6
20.0 or greater
100 kA OR GREATER
*478
In-line isolatedphase bus
Interrupting Medium
SF6 or air blast
* 478 MVA @ 20 kA
employ employ either either SF6 or compre compresse ssed d air insula insulatin ting g and arc extinguishing systems and can incorporate breaker isolating switch switches es in the breake breakerr compartm compartment ent.. This This type type of breake breakerr requir requires es less less space space than than a statio station n type type cubicl cubiclee breaker breaker but has higher initial initial cost. It should receive receive conside sidera rati tion on wher wheree powe powerh rhou ouse se spac spacee is at a prem premiu ium. m. Technical operating parameters and performance are covered in IEEE C37.013.
(2) The essent essential ial featur features es of draw-o draw-out ut metalmetal-cla clad d switchgear and station type cubicle switchgear are covered in IEEE C37.20.2. C37.20.2. Essential Essential features features of in-line in-line isolatedisolatedphas phasee busbus-ty type pe circ circui uitt brea breake kers rs are are cove covere red d in IEEE IEEE C37.01 C37.013 3 and C37.23. C37.23. Specif Specific ic curren currentt and interru interrupti pting ng rati rating ngss avai availa labl blee at othe otherr volt voltag ages es are are summ summar ariz ized ed in Tables 6-2 and 6-3.
Table 6-2 Indoor Metal-Clad Switchgear, Removable Breaker Nominal Ratings Phase protection is by insulated buses
Current (kA)
Short-Circuit Rating (kA)
Interrupting Rating (kA)
Closing Mechanism
1.36 1.24 1.19
1.2 1.2, 2 1.2,2,3
8.8 29 41
12 36 49
Stored Energy "
1.25
1.2, 2
33
41
"
15.0 15.0 15.0
1.3 1.3 1.3
1.2, 2 1.2, 2 1.2,2,3
18 28 37
23 36 48
" " "
38.0 38.0
1.65 1.00
1.2,2,3 1.2, 3
21 40
35 40
" "
Voltage Rating Factor K
4.76 4.76 4.76 8.25
Voltage (kV )
Note: The voltage voltage range factor, K, is the ratio of maximum maximum voltage to the lower limit of the range of operating operating voltage in which the required required symmetrica symmetricall and asymmetrical asymmetrical current current interrupting interrupting capabilities capabilities vary in inverse proportion proportion to the operating operating voltage. voltage. See ANSI C37.06.
6-4
EM 1110-2-3006 30 Jun 94 Table 6-3 Indoor Metal-Enclosed Switchgear, Fixed Breaker Preferred Ratings For Generator Circuit Breakers 4/ Phase protection is by steel barriers
Voltage (kV )
Voltage Rating Factor K
15.8 27.5
1 1
Current (kA)
ShortCircuit Rating (kA)
Interrupting Rating (kA)
Closing Mechanism
1/ 1/
2/ 2/
3/ 3/
Stored Energy
1/ Typical values, in kA: 6.3, 8.0, 10.0, 12.0, 16.0, 20.0, 25.0, 30.0 and 40.0. 2/ Typical Typical values in kA: 63, 80, 100, 120, 160, 200, 250, 250, 275. 3/ Symmetrical interrupting capability for polyphase faults shall not exceed the short-circuit short-circuit rating. Single-phase-to-ground fault interrupting capability shall not exceed 50A. 4/ IEEE C37.013.
6-5
EM 1110-2-3006 30 Jun 94
Chapter 7 Station Service System
7-1. 7-1. Power Power Suppl Supply y a. Genera Generall.
A compl complet etee stati station on serv servic icee suppl supply y and distributi distribution on system system should should be provided provided to furnish furnish power for statio station, n, dam auxili auxiliari aries, es, lighti lighting, ng, and other other adjace adjacent nt feat featur ures es of the the proj projec ect. t. The The loss loss of a stat statio ion n serv servic icee sour source ce,, eith either er thro throug ugh h swit switch chin ing g oper operat atio ions ns or due due to protective relay action, should not leave the plant without servic servicee power. power. The station station service service system system should should have have a minimum of two full-capacity, redundant power sources. b. Plant “black “black start” start” capability capability.
(1) Genera General. l. “Black “Black start” start” capabi capabilit lity y is desira desirable ble at hydro plants since the plants can assist in re-establishing generatio generation n for the power system in an emergency. emergency. “Black “Black star start” t” capa capabi bili lity ty is defi define ned d as the the abil abilit ity y of the the plan plant, t, withou withoutt an extern external al source source of power, power, to mainta maintain in itself itself intern internall ally, y, start start genera generatin ting g units, units, and bring bring them them up to speed-no-l speed-no-load oad condition conditions, s, close the generator generator breakers, breakers, energize transformers and transmission lines, perform line charging as required, and maintain units while the remainder der of the the grid grid is re-e re-est stab abli lish shed ed.. The The plan plantt must must then then resynchron resynchronize ize to the grid. (2) Power system system proble problems. ms. (a) There are a number number of circumstance circumstancess that can lead to collap collapse se of all or parts parts of a bulk bulk power power distri distribut bution ion system system.. Regard Regardles lesss of the circum circumsta stance nces, s, the trigge triggerin ring g event event genera generally lly leads leads to region regional al and subreg subregion ional al mismismatch of loads and generation and “islanding” (i.e., plants providing providing generatio generation n to isolated isolated pockets pockets of load). load). SeparaSeparation tion of gene genera rati tion on reso resour urce cess from from remo remote te load loadss and and “islanding” can cause voltage or frequency excursions that may result in the loss of other generation resources, particula ticularly rly steam steam genera generatio tion, n, which which is more more sensit sensitive ive to frequency frequency excursions excursions than hydroelect hydroelectric ric turbine turbine generagenerators. Steam generat generation ion is also harder harder to return to service service than hydro generation, so the burden of beginning system restoration is more likely to fall on hydro resources. (b) When a transmissio transmission n line is removed from from service by protective relay action, the power it was carrying will either seek another transmission line route to its load, or be interrup interrupted ted.. If its power power is shifte shifted d to other transmi transmisssion lines, those lines can become overloaded and also be remo remove ved d from from serv servic icee by prot protec ecti tive ve rela relays ys.. Syst System em
failures are more likely to happen during heavy load periods, ods, when when failur failures es cascad cascadee becaus becausee of stress stress on the system. tem. If the hydro hydro unit unitss are are runn runnin ing g at or near near full full load load when when the plant is separa separated ted from the system, system, they they will will experience load rejections. (c) Units Units subjec subjected ted to a load load reject rejection ion are design designed ed to go to spee speedd-no no-l -loa oad d unti untill thei theirr oper operat atin ing g mode mode is change changed d by contro controll action action.. Someti Sometimes mes,, howeve however, r, they shut shut down down comp comple lete tely ly,, and and if stat statio ion n serv servic icee is bein being g suppli supplied ed by a unit unit that that shuts shuts down, down, that that source source will be lost. lost. Units Units can’t be started, started, or kept kept on line, line, withou withoutt govgoverno ernorr oil oil pres pressu sure re,, and and gove govern rnor or oil oil pres pressu sure re can’ can’tt be maintained without a source of station service power for the governor oil pumps. (d) Assump Assumptio tions ns made made concer concernin ning g plant plant condit condition ionss when the transmiss transmission ion grid collapses, collapses, thus initiati initiating ng the need need for for a “bla “black ck star start, t,”” will will defi define ne the the equi equipm pmen entt requireme requirements nts and operating operating parameters parameters which the station station service service design must meet. meet. At least one emergency emergency power source source from an automatic automatic start-eng start-engineine-drive driven n generator generator should be provided for operating governor oil pumps and re-establ re-establishin ishing g generatio generation n after after losing losing normal normal station station service power. c. For large large power power plants plants.
(1) Two station service service transformer transformerss with buses and swit switch chin ing g arra arrang nged ed so that that they they can can be supp suppli lied ed from from either either the main main genera generator torss or the transm transmiss ission ion system system should should be provid provided, ed, with with each each transf transform ormer er capabl capablee of supplying supplying the total total station station load. A unit that will be operated in a base load mode should be selected to supply a statio station n servic servicee transf transform ormer, er, if possib possible. le. Statio Station n servic servicee source source select selection ion switch switching ing that that will will allow allow supply supply from from eith either er a main main unit unit or the the powe powerr syst system em shou should ld be proprovide vided. d. The The swit switch chin ing g shou should ld be done done by inte interl rloc ocke ked d breakers to prevent inadvertent parallel operation of alternate nate sources. sources. If a main main unit is switched switched on as a source source,, then then the the supp supply ly shou should ld not not depe depend nd on that that unit unit bein being g connec connected ted to the power system. system. If the power system system is swit switch ched ed on as the the sour source ce,, then then the the supp supply ly shou should ld not not depend on any units being connected to the power system. (2) To meet Federal Energy Regulatory Regulatory Commissio Commission n (FERC) (FERC) requir requireme ements nts,, all reserv reservoir oir projec projects ts should should be equipped equipped with an engine-dri engine-driven ven generator generator for emergency emergency standb standby y servic servicee with with suffic sufficien ientt capaci capacity ty to operat operatee the spillway gate motors and essential auxiliaries in the dam. The unit is usually installed in or near the dam rather than in the powerhou powerhouse. se. It may also be used to provid providee emergency service to the powerhouse, although the use of long
7-1
EM 1110-2-3006 30 Jun 94 supply cables from the dam to the powerhouse could be a disadvantage. (3) For a large large power plant, plant, a second second automat automatic ic start emerge emergency ncy power power source source may be requir required ed in the powerpowerhouse. house. Besides Besides diesel engine-ge engine-genera nerators, tors, small small combustion tion turb turbin ines es are are an opti option on,, alth althou ough gh they they are are more more complex and expensive than diesel engine-generator sets. (4) (4) Any Any emer emerge genc ncy y sour source ce shou should ld have have auto automa mati ticc star startt cont contro rol. l. The The sour source ce shou should ld be star starte ted d when whenev ever er stat statio ion n serv servic icee powe powerr is lost lost.. The The emer emerge genc ncy y sour source ce cont contro roll shou should ld also also prov provid idee for for manu manual al star startt from from the the plant plant control control point. point. It is also also import important ant to provid providee local local control at the emergency source for non-emergency starts to test and exercise exercise the emergen emergency cy source. source. A load load shedshedding scheme may be required for any emergency source, if the source capacity is limited. d. For For smal small, l, oneone-un unit it powe powerr plan plants ts.
One One sta stattion ion service transformer supplied from the transmission system should be provided for a normal station service bus, and an emergency station service bus should be supplied from an engine-driven engine-driven generator. generator. The emergency emergency source should have have suff suffic icie ient nt capa capaci city ty to oper operat atee the the spil spillw lway ay gate gate motors and minimum essential auxiliaries in the dam and powe powerh rhou ouse se such such as unwa unwate teri ring ng pump pumps, s, gove govern rnor or oil oil pumps, and any essential preferred AC loads. e. Station service service distributio distribution n system.
(1) In many plants, plants, feeders feeders to the load centers centers can be desi design gned ed for for 480480-V V oper operat atio ion. n. In a larg largee plan plant, t, wher wheree large large loads loads or long long feeder feeder lengths lengths are involved involved,, use of 13.8-kV or or 4.16-kV distribution distribution circuits will be satisfactory when when econ econom omic ical ally ly just justif ifie ied. d. Dupl Duplic icat atee feed feeder erss (one (one feeder feeder from from each each statio station n servic servicee supply supply bus) bus) should should be provided provided to important important load centers. centers. Appropriat Appropriatee controls and interlocking interlocking should be incorporat incorporated ed in the design design to ensure that critical load sources are not supplied from the same same bus. bus. Feed Feeder er inte interl rloc ock k arra arrang ngem emen ents ts,, and and sour source ce transfer, should be made at the feeder source and not at the distribution centers. (2) The distri distribut bution ion system system contro controll should should be thorthoroughly evaluated to ensure that all foreseeable contingencies cies are covere covered. d. The load center centerss should should be located located at accessible accessible points for convenienc conveniencee of plant operation operation and accessibil accessibility ity for servicing servicing equipment. equipment. Allowance Allowance should be made for the possibility of additional future loads. (3) All of the auxilia auxiliary ry equipmen equipmentt for a main main unit unit is usually fed from a motor control center reserved for that
7-2
unit unit.. Fee Feeders ders shou should ld be siz sized base based d on maxi aximum mum expect expected ed load, load, with with proper proper allowa allowance nce made made for voltag voltagee drop, motor starting inrush, and to withstand short-circuit curren currents. ts. Feeder Feederss that that termin terminate ate in expose exposed d locati locations ons subject to lightning should be equipped with surge arresters outside of the building. (4) Three-phas Three-phase, e, 480-V station service service systems using an ungroundedungrounded-delta delta phase arrangeme arrangement nt have the lowest lowest first cost. cost. Such systems systems will tolerate, tolerate, and allow detection detection of, single single accidental accidental grounds without without interrupti interrupting ng service service to loads. Three-phas Three-phase, e, grounded-wye grounded-wye arrangeme arrangements nts find widesp widesprea read d use in the indust industria riall sector sector and with with some some regula regulator tory y author authoriti ities es becaus becausee of percei perceived ved benefi benefits ts of safety safety,, reliab reliabili ility, ty, and lower lower mainte maintenan nance ce costs costs over over a 480-V 480-V delta delta system. system. Indust Industria riall plants plants also have a higher higher percentage percentage of lighting lighting loads in the total total plant load. InstalInstallation lation costs costs for providing providing service to large concentratio concentrations ns of high high-i -int nten ensi sity ty ligh lighti ting ng syst system emss are are lowe lowerr with with 480/277-V 480/277-V wye systems. systems. Delta systems systems are still preferred preferred in hydro hydro statio stations ns becaus becausee of the cleane cleanerr enviro environme nment, nt, good service service record, record, and skilled skilled electrici electricians ans available available to maintain the system. f. Station service switchgear .
(1) Metal-cla Metal-clad d switchgear switchgear with SF 6 or vacuum circuit breake breakers rs should should be suppli supplied ed for statio station n servic servicee system system voltage voltage above 4.16 kV . MetalMetal-enc enclos losed ed switchge switchgear ar with 600600-V V draw drawou outt air air circ circui uitt brea breake kers rs shou should ld be used used on 480-V station station service service systems. systems. The switchgear switchgear should should be located near the station service transformers. (2) (2) The The stat statio ion n serv servic icee swit switch chge gear ar shou should ld have have a sectionalized bus, with one section for each normal station servic servicee source. source. Switch Switching ing to connec connectt emergenc emergency y source source power power to one of the buses, buses, or select selective ively, ly, to either either bus shou should ld be prov provid ided ed.. If the emer emerge genc ncy y sour source ce is only connec connected ted to one bus, then then the reliabil reliability ity of the station station servic servicee source source is compro compromis mised ed since since the bus suppli supplied ed from the emergency source could be out of service when an emergenc emergency y occurr occurred. ed. It is prefer preferabl ablee that that the emeremergency source be capable of supplying either bus, with the breakers breakers interlocked interlocked to prevent prevent parallel parallel operation operation of the buses from the emergency source. (3) Each Each supply supply and bus tie breaker breaker should should be elecelectrical trically ly operat operated ed for remote remote operat operation ion from from the contro controll room room in attend attended ed station stations. s. As a minim minimum, um, bus voltage voltage indication for each bus section should be provided at the remote remote point point where where remote remote plant plant operat operation ion is provid provided. ed. Transfer between the two normal sources should be automatic. matic. Transf Transfer er to the emerge emergency ncy power sources sources should should
EM 1110-2-3006 30 Jun 94 also also be automa automatic tic when when both both normal normal power power source sourcess fail. fail. Feeder Feeder switching switching is performed performed manually manually except except for specific applications. (4) In large station station service service systems systems with a double double bus arrangement, source/bus tie breakers should be located at each end of the switchgear switchgear compartmen compartment. t. The source/bus source/bus tie breake breakers rs should should not be locate located d in adjace adjacent nt compar comparttments because a catastrophic failure of one breaker could destroy destroy or damage damage adjacent adjacent breakers leading to complete complete loss loss of station station service service to the plant. plant. In large plants plants where where ther theree is suff suffic icie ient nt spac space, e, it is even even safe saferr to prov provid idee a separa separate, te, parall parallel el cubicl cubiclee lineup lineup for each each statio station n servic servicee bus for more complete complete physical physical isolati isolation. on. Even with this this arrangement, feeder and tie breakers should not be located in adjacent compartments. (5) (5) For For 480480-V V stat statio ion n serv servic icee syst system ems, s, a delt deltaaconnec connected ted,, ungrou ungrounde nded d system system is recomm recommend ended ed for the following reasons: (a) Nature Nature of the loads loads.. The load load in a hydroe hydroelec lectri tricc power plant plant is made up predominantl predominantly y of motor loads. In a commercial or light industrial facility, where the load is predom predomina inantl ntly y light lighting ing,, the instal installat lation ion of a 480/27 480/277 7 V, wye-connected system is more economical due to the use of higher higher voltag voltages es and smalle smallerr conduc conductor tor sizes. sizes. These These econom economies ies are not realiz realized ed when when the load load is predom predomiinantly nantly motor loads. For high bay lighting systems, systems, certain certain installation economies may be realized through the use of 480/27 480/277-V 7-V wye-co wye-conne nnecte cted d subsys subsystem tems, s, as descri described bed in Chapter 12. (b) Physic Physical al circui circuitt layout layout.. Wye-co Wye-conne nnecte cted d system systemss allow the ability to quickly identify and locate a faulted circuit circuit in a widely dispersed dispersed area. Although Although hydroelectr hydroelectric ic power power plants plants are widely widely disper dispersed sed,, the 480-V 480-V system system is concen concentra trated ted in specif specific ic geogra geographi phicc locale localess within within the plant, allowing rapid location of a faulted circuit, aided by the ground detection system described in paragraph 7-2.
7-2. 7-2. Rel Relays ays An overlapping protected zone should be provided around circuit circuit breakers. breakers. The protective protective system system should operate operate to remove the minimum possible amount of equipment from serv servic ice. e. Over Overcu curr rren entt rela relays ys on the the supp supply ly and and bus bus tie tie breake breakers rs should should be set so feeder feeder breakers breakers will trip on a feeder feeder fault without without tripping tripping the source breakers. breakers. Ground overcurre overcurrent nt relays relays should should be provided provided for wye-connec wye-connected ted statio station n servic servicee system systems. s. Ground Ground detecti detection on by a voltag voltagee relay connected in the broken delta corner of three potential tial transf transform ormers ers should should be provid provided ed for ungrou ungrounde nded d or
delta-con delta-connecte nected d systems (ANSI C37.96). Bus differential differential relays relays should should be provid provided ed for statio station n servic servicee system systemss of 4.16 kV and and high higher er volt voltag age. e. The The adju adjust stab able le trip trippi ping ng device built into the feeder breaker is usually adequate for feeder feeder protectio protection n on station station service service systems systems using 480-V low-voltage switchgear.
7-3. Control Control and Metering Metering Equipment Equipment Indicating instruments and control should be provided on the station station service switchgear switchgear for local control. control. A voltmeter, ter, an ammete ammeter, r, a wattm wattmete eter, r, and a wattho watthour ur meter meter are usually usually sufficient. sufficient. A station service annunciat annunciator or should be provid provided ed on the switch switchgea gearr for a large large statio station n servic servicee system. system. Contact-m Contact-making aking devices devices should be provided provided with the watthour meters for remote remote indicatio indication n of station station service vice energy energy use. Addit Addition ional al auxiliar auxiliary y cabine cabinets ts may be required for mounting breaker control, position indication, protec protectiv tivee relays relays,, and indicati indicating ng instru instrumen ments. ts. For large large plants, plants, physical physical separation separation of control control and relay cubicles cubicles should should be consid considere ered d so contro controll and relayi relaying ng equipm equipment ent will not be damaged or rendered inoperable by the catastrophic failure of a breaker housed in the same or adjacent cubicle.
7-4.
Load/Distribu Load/Distribution tion Centers Centers
Protective and control devices for station auxiliary equipment ment shou should ld be grou groupe ped d and and moun mounte ted d in dist distri ribu buti tion on centers centers or, preferably, preferably, motor motor control centers. centers. The motor star starte ters rs,, circ circui uitt beak beaker ers, s, cont contro roll swit switch ches es,, tran transf sfer er swit switch ches es,, etc., etc., shou should ld all all be loca locate ted d in moto motorr cont contro roll centers.
7-5. Estimated Estimated Station Station Service Service Load a. Genera Generall.
(1) The maximum maximum demand demand that that is expected expected on the station station service system is the basis for developing developing station station service service transformer transformer ratings. ratings. The expected expected demand may be determined from a total of the feeder loads with an appropriate priate divers diversity ity factor factor,, or by listin listing g all connec connected ted loads loads and corres correspon pondin ding g demand demand loads loads in kVA. A dive divers rsit ity y factor factor smaller smaller than 0.75 should should not be used. During During high activity periods or plant emergencies, higher than normal station service loads can be expected and if a small diversity factor has been used, the system may not have adequate capacity to handle its loads. (2) (2) Dema Demand nd fact factor orss used used for for deve develo lopi ping ng stat statio ion n servic servicee equipm equipment ent capaci capacitie tiess can vary vary widely widely due to the type type of plant plant (high (high head head standstand-alo alone ne power power plant plant versus versus
7-3
EM 1110-2-3006 30 Jun 94 low head power plant integrated with a dam structure and navigatio navigation n lock). Developmen Developmentt of demand demand factors for unit auxiliaries should account for the type of auxiliaries in the plan plantt base based d on tren trends ds obse observ rved ed at simi simila larr plan plants ts.. For For inst instan ance ce,, the the gove govern rnor or oil oil pump pump dema demand nd for for a Kapl Kaplan an turbine will be greater than that for the governor oil pump demand demand for a Franci Franciss turbin turbinee of the same output output rating rating becaus becausee of the additi additiona onall hydrau hydraulic lic capaci capacity ty needed needed to operat operatee the Kaplan Kaplan turbin turbinee blades blades.. If the plant plant is base base load loaded ed,, gove govern rnor or oil oil pump pumpss will will not not cycl cyclee as ofte often n as governor oil pumps in a similar plant used for automatic generation control or peaking service. (3) (3) Stat Statio ion n serv servic icee syst system emss shou should ld be desi design gned ed to antici anticipat patee load load growth growth.. Antici Anticipat pated ed growth growth will depend depend on a number of factors including size of the plant, location, and whether the plant will become an administrative center center.. A oneone- or two-un two-unit it isolated isolated plant plant not suitabl suitablee for addition of more units would not be expected to experience ence a dramat dramatic ic increa increase se in demand demand for statio station n servic servicee power. power. For such such a plant, plant, a contin contingen gency cy for load growth growth of 20 percent percent would be adequate. adequate. Conversely Conversely,, some large mult multii-pu purp rpos osee plan plants ts have have expe experi rien ence ced d 100100-pe perc rcen entt increases increases in the connected kVA loads loads on the station station serservice system over original design requirements.
(4) Capacity Capacity deficits deficits in existing station station service service systems have not been caused by the designer’s inability to predict predict unit auxiliary auxiliary requireme requirements, nts, but by unforeseea unforeseeable ble demands to provide service for off-site facilities added to multip multipurp urpose ose project projects. s. Exampl Examples es of this this have have been been the develo developme pment nt of extens extensive ive mainte maintenan nance ce and wareho warehouse use facili facilitie tiess outsid outsidee the power power plant, plant, or electr electrica icall requir requireements resulting from environmental protection issues such as fish fish bypa bypass ss equi equipm pmen ent. t. The The stat statio ion n serv servic icee desi design gn should should have provisions provisions for unanticipated unanticipated load growth growth for multipurpose projects with navigation locks and fish ladders. For such projects, projects, a minimum minimum growth factor factor contincontingency adder of 50 percent could be justified. b. Auxilia Auxiliary ry demand demand . Dema Demand nd varie variess grea greatl tly y with with different different auxiliaries, auxiliaries, and the selection selection of demand demand factors factors requ requir ires es reco recogn gnit itio ion n of the the way way vari variou ouss powe powerr plan plantt equipm equipment entss will will be operat operated. ed. One method method illust illustrat rated ed in Table 7-1 assumes 1 hp as the equivalent of 1 kVA and on lights and heaters uses the kW rating as the kVA equivalent. lent. The accurac accuracy y of the method method is within within the accuracy accuracy of the assump assumptio tions ns of demand demand and diversit diversity. y. The values values of demand demand and divers diversity ity factor factorss correl correlate ate with with trends trends observed in recent years on station service loads.
Table 7-1 Estimated Station Service Load and Recommended Transformer Capacity Connected Load kVA
Function Unit Auxiliaries Auxiliaries for 8 Units Governor Oil Pump Pump #1 Bus #1 Pump #2 Bus #2 Pump #3 Bus #1 Pump #4 Bus #2 Turbine Bearing Oil Pump Head Cover Pump Pump #1 Bus #1 Pump #2 Bus #2 High Bay Lights Bus #1 Bus #2 Generator Housing Heater Transformer Cooling Water Pumps Bus #1 Bus #2 Transformer Oil Pump Bus #1 Bus #2 ACB Air Compressor Bus #1 Bus #2
8 8 4 4 8
@ @ @ @ @
8@ 8@
100 hp 100 hp 25 hp 25 hp 1 hp 2 hp 2 hp
800.00 800.00 100.00 100.00 8 .0 0
400.00
16.00 16.00
16.00
91 91.00
50.00 8. 8.00
7 @ 13 kW 7 @ 13 kW 8 @ 18 kW
91.00 91.00 144.00*
2 @ 50 hp 2 @ 50 hp
100.00 100.00
100.00
24.00 24.00
24.00
5 .0 0 10.00
5. 5.00 10.00
12 @ 12 @
2 hp 2 hp
1 @ 5 hp 1 @ 10 hp (Continued)
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Demand kVA
EM 1110-2-3006 30 Jun 94
Table 7-1 7-1 (Concluded) (Concluded) Connected Load kVA
Function High Pressure Thrust Bearing Oil Pump Governor Air Compressor
8 @ 10 hp 2 @ 15 hp
General Auxiliaries Supply to Dam Fire Pump HVAC-Heat Pump Transit Oil Processor Transit Oil Pump Battery Charger No. 1 Battery Charger No. 2 Elevator Power Outlets Draft Tube Crane Duplex Sump Pump Powerhouse Crane No. 1 Air Compressor No. 1 Air Compressor No. 2 Filter Paper Oven Lubricating Oil Purifier Lubricating Oil Pump Water Heater - 20 gal. Water Heater - 100 gal. Switchyard Cable Tunnel Ventilating Fan Power Outlets Lighting Air Compressors
80.00 30.00
696 25 380 20 10 10 10 25 -50 15 100 20 20 2 14 5 2 5
5 37.5 6
Machine Shop Largest Machine Total less heating Total demand with diversity diversity factor of 75 percent
Demand k VA
2 05 25 36 20 10 10 0** 25 25 25 0 7.5 0 20 0** 2 14 0 2 2
5 5 30 2
15 3852.5
11 64 . 50
873.4 kVA
Estimated total heating load
1055.0 kVA
Estimated total demand load with heating
1928.4 kVA
Recommended size of each station service transformer
1500.0 kVA
* Not on when generator running. ** Standby
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EM 1110-2-3006 30 Jun 94
Chapter 8 Control System
8-1. 8-1. Genera Generall a. Scop Scopee.
The The cont contro roll syst system em as disc discus usse sed d in this this chapter chapter deals deals with equipment equipment for the control control and protection of apparatus apparatus used for power generatio generation, n, conversio conversion, n, and transmiss transmission. ion. It does not include include low-voltage low-voltage panelboards and industrial control equipment as used with plant auxil auxiliar iaries ies.. IEEE IEEE 1010 1010 and EPRI EL-5036 EL-5036,, Volume Volume 10, provid providee guidel guideline iness for planni planning ng and design designing ing contro controll systems for hydroelectric power plants. b. Contro Controll system system compon components ents.
The The contr control ol syst system em consis consists ts primar primarily ily of a comput computerer-bas based ed contro controll system system,, hard-wired hard-wired logic or programma programmable ble logic, logic, indicatin indicating g and recording recording instrument instruments, s, control control switches, switches, protectiv protectivee relays, relays, and similar similar equipme equipment. nt. The greates greatestt part part of this equipequipment ment shou should ld be grou groupe ped d at one one loca locati tion on to faci facili lita tate te superv supervisi ision on and operat operation ion of the main main genera generatin ting g units, units, transmiss transmission ion lines, and station station auxiliaries auxiliaries.. The grouping grouping of these controls at one location within the confines of the power plant is termed “centralized control.” c. Start-s Start-stop top sequen sequence ce.
Each Each genera generato torr unit unit contr control ol system should be provided with a turbine/generator startstop sequencing logic using a master relay located at the genera generator tor (or unit) unit) switch switchboa board. rd. The starting starting sequence sequence begins with pre-start checks of the unit, followed by starting unit auxiliaries, and ends with the unit operating under the speed-no speed-no-lo -load ad condit condition ion.. Manual Manual or automa automatic tic synchroni chronizin zing g and closure closure of the unit breake breakerr can be perperform formed ed at the the loca locall cont contro roll loca locati tion on.. The The stop stoppi ping ng sequence should provide for four types of unit shutdown: protec protectiv tivee relayi relaying, ng, operat operator’ or’ss emerge emergency ncy stop stop switch switch,, mechanical problems, and normal shutdown. d. Generator Generator switchboards switchboards.
Genera Generator tor swit switchb chboar oards ds in larg larger er powe powerr plan plants ts are are loca locate ted d near near the the cont contro roll lled ed generator generator.. The switchboard switchboardss provide local control control of the unit. unit. In smalle smallerr power power plants plants,, where where metalmetal-cla clad d switch switch-gear gear is used used for for swit switch chin ing g the the gene genera rato tor, r, unit unit cont contro roll equipment is located on auxiliary panels of the switchgear line-up. line-up. Like the switchboard switchboards, s, the auxiliary auxiliary panel equipment provides local control of the unit. e. Auxilia Auxiliary ry equipme equipment nt contro controll.
Larg Largee power power pla plant ntss using using high-v high-volt oltage age busing busing and switch switching ing or having having an adjace adjacent nt switch switchyar yard d as part part of the develo developme pment nt should should have have contro controll for this this equipm equipment ent locate located d in the groupi grouping ng sugg sugges este ted d in para paragr grap aph h 8-1( 8-1(b). Even though the
controlled equipment is remote from the plant, the equipment is not “offsite.” “offsite.” Offsite Offsite control denotes denotes control from a location not resident to the plant, i.e., another plant or a control complex at another location. f. Control room location. In plants plants with with a few units units,,
the contro controll room room locati location on with with its centra centraliz lized ed contro controls ls should provide ready access to the governor control cabinets nets.. In plan plants ts with with ulti ultima mate tely ly four or more more unit units, s, the the cont contro roll room room shou should ld be loca locate ted d near near the the cent center er of the the ultimate plant or at a location allowing ready access to the units units and adjace adjacent nt switchya switchyard. rd. The relative relative number number and lengths of control circuits to the units and to the switchyard is a factor to consider, but is secondary to consideration ation of operating operating convenien convenience. ce. The control control room should be an elevat elevation ion above maximum maximum high high water, water, if there there is any danger danger that that the plant may be flooded flooded.. A decisi decision on on the location of the control room should be reached at an early stage of plant design, since many other features of the plant are affected affected by the control control room location. location. Control trol locati location on defini definitio tions ns and contro controll modes modes are furthe furtherr described in IEEE 1010. g. Smaller Smaller plants plants.
In small smaller er power power plant plants, s, where where indoor indoor generator generator-volt -voltage age busing busing and switching switching are used, hing hinged ed inst instru rume ment nt pane panels ls on the the swit switch chge gear ar cubi cubicl cles es should be used as mounting space for main control equipment. ment. This This results results in the main group group of contro controll equipequipment being located at the main switchgear location.
8-2. Control Control Equipment Equipment a. Genera Generall. Centra Centraliz lized ed automati automaticc and manual manual con-
trol trol equipm equipment ent should should be locate located d in the control control room room of large large power power plants plants.. The control control consol console, e, in conjun conjuncti ction on with supervisory supervisory control control and data acquisition acquisition (SCADA) equipment and the status switchboard, enables the control room room oper operat ator or to cont contro roll the the powe powerh rhou ouse se oper operat atio ion. n. Equipm Equipment ent racks racks housin housing g automa automatic tic synchr synchroni onizin zing g and centra centraliz lized ed auxili auxiliary ary equipm equipment ent should should be locate located d in or adjacent to the control room to facilitate connections with contro controll room room equipm equipment ent.. If the plant plant is contro controll lled ed from from offsite, offsite, the plant’s plant’s SCADA equipment equipment should should be located located in or adjacent to the control room. b. Spac Spacee allo alloca catio tion n. Spa Space allo allottted ted for for cont ontrol rol equipment, whether in a separate control room or in the main main switch switchgea gearr cubicl cubiclee area, area, must must be large large enough enough to accommodate the panels required for the ultimate number of gene genera rati ting ng unit unitss and and tran transm smis issi sion on line lines. s. The The spac spacee requirement, as well as the size and location of openings required in the floor, should be provided to the architectural tural and structura structurall designers designers to ensure ensure proper proper considerconsideration in door, room, and floor slab designs.
8-1
EM 1110-2-3006 30 Jun 94 c. Cabinet Cabinet construction construction. Genera Generator tor switch switchboa board rd pan-
els els and and door doorss shou should ld be 1/81/8-in in.. thic thick k or No. No. 11 U.S.S U.S.S.. gauge gauge smooth smooth select select steel with with angle angle or channe channell edges edges bent bent to approxim approximate ately ly a 1/4-in 1/4-in.. radius radius.. Panels Panels should should be mounte mounted d on sills sills ready ready for powerh powerhous ousee instal installat lation ion in grou groups ps as larg largee as can can be ship shippe ped d and and move moved d into into the the inst instal alla lati tion on area area.. All All equi equipm pmen entt on the the swit switch chbo boar ards ds shou should ld be moun mounte ted d and and wire wired d at the the fact factor ory, y, and and the the boar boards ds shou should ld be ship shippe ped d to the the powe powerh rhou ouse se with with all all equipment in place. d. Equipme Equipment nt arrang arrangeme ement nt . The arrangement of equipm equipment ent on the contro controll switch switchgea gear, r, switch switchboa board, rd, or contro controll consol consolee should should be carefu carefully lly planne planned d to achiev achievee simpli simplicit city y of design design and to replic replicate ate unit unit contro controll placeplacements ments familiar to the intended operating operating staff. staff. Simplicit Simplicity y of design is a definite aid to operation and tends to reduce operating errors; therefore, the relative position of devices should should be logica logicall and uniform. uniform. Switch Switchboa board rd and control control consol consolee design design should should be patter patterned ned after after an approp appropria riate te exam exampl plee to atta attain in a degr degree ee of stan standa dard rdiz izat atio ion n in the the arrangeme arrangement nt of indicatin indicating g instrument instrumentss and basic control swit switch ches es.. Cont Contro roll swit switch ches es shou should ld be equi equipp pped ed with with distin distincti ctive ve handles handles as shown shown in Table Table 8-1. Each Each item item of equipment should be located by consideration of its functions, its relation to other items of equipment, and by its use by the operator.
8-3. Turbine Governor Governor The digital digital governor electrical electrical control control cabinet cabinet usually usually is locate located d adjace adjacent nt to the genera generator tor switch switchboa board rd separa separate te from from the actuato actuatorr cabine cabinet. t. The control control cabine cabinett contai contains ns govern governor or electr electroni onicc or digita digitall “propo “proporti rtiona onal-i l-inte ntegra grallderiva derivativ tive” e” (P-I-D (P-I-D)) contro controll compon component ents. s. The actuat actuator or cabine cabinett housin housing g the power power hydrau hydraulic licss of the govern governor or syst system em is loca locate ted d to mini minimi mize ze the the pres pressu sure re line line runs runs betwee between n the turbin turbinee servom servomoto otors, rs, the actuat actuator, or, and the govern governor or pressu pressure re tank. tank. For smalle smallerr capaci capacity ty govern governors ors and smalle smallerr plants plants,, govern governor or electr electroni onicc and hydrau hydraulic lic controls controls are all located in the governor actuator actuator cabinet. cabinet. For mechanical mechanical consideratio considerations ns of turbine turbine governors, governors, see EM 1110-2-4205.
monito monitorin ring g equipm equipment ent in conjun conjuncti ction on with with a comput computererbased data acquisiti acquisition on and control system (DACS), provides control and indication access to individual items of equipment to facilitate operation, supervision, and control. Hard-wired pushbutton switches provide for direct operator manual control of unit start-stop, breaker close (initiating ing auto automa mati ticc sync synchr hron oniz izin ing) g),, brea breake kerr trip trip,, volt voltag age, e, load loadin ing, g, and and gate gate limi limitt rais raisee-lo lowe wer. r. Anal Analog og or digi digita tall panel meters and indicating indicating lights continuous continuously ly indicate indicate the status status of all main main units, units, breake breakers, rs, transf transform ormers ers,, and lines. lines. The DACS system display display monitors monitors and keyboards keyboards are availab available le to operat operator or control. control. The unit control controlss and instruments supplement or duplicate those on the generator switch switchboa board, rd, and provid providee the contro controll room room operat operator or with the ability to transfer control of any selected unit or grou group p of unit unitss to the the gene genera rato torr swit switch chbo boar ard d in case case of system system troubl trouble. e. The control control console console may also provide provide spillway spillway gate control, control, fishway fishway control, control, project project communicommunication cations, s, and other other projec projectt equipm equipment ent contro controll functi functions ons when required. b. Equipm Equipment ent location location. Arrang Arrangeme ement nt of control control and and
instru instrumen mentt switch switches es and mimic mimic bus should should simula simulate te the relative order of interconnections or physical order of the plant plant arrang arrangeme ement nt assist assisting ing the operat operator or in formi forming ng a ment mental al pict pictur uree of conn connec ecti tion ons. s. The The top top of the the cont contro roll console panel should be inclined to provide easier access to the control switches and to improve console visibility. Layo Layout utss of cons consol olee visu visual al disp displa lay y term termin inal alss (VDT (VDTs) s) should should follow follow applic applicabl ablee guidel guideline iness contai contained ned in ChapChapter 12, “Lighting and Receptacle Systems,” to ensure good visual visual acuity acuity of the display displays. s. Panels Panels of the control control conconsole should be arranged for ultimate development, so that the additi addition on of a contro controll panel panel for another another genera generator tor or another another line will not disturb disturb existing existing equipment. equipment. c. Status Status switchboa switchboard rd . The status status switch switchboa board rd concontains graphic and visual indication, generator load recorders, station total total megawatts megawatts and megavars megavars recorders, recorders, and other other requir required ed projec projectt data data displa displays. ys. The status status switch switch-board board should should be locate located d for easy easy observ observati ation on from from the cont contro roll cons consol ole. e. The The stat status us swit switch chbo boar ard d shou should ld be a standard standard modular modular vertical vertical rack enclosure enclosure joined together together to form a freestanding, enclosed structure.
8-4. Large Power Power Plant Plant Control Control d. Equipm Equipment ent racks racks.
a. Genera Generall. Centralize Centralized d control control system equipme equipment nt is locate located d in the control control room room and is interc interconn onnect ected ed to the genera generator tor switchbo switchboard ardss locate located d near near the units. units. Requir Required ed control and monitoring of all functions of the hydroelectric tric powe powerr proj projec ectt are are prov provid ided ed to the the oper operat ator ors. s. The The contro controll consol consolee with with conven conventio tional nal contro controll device devicess and
8-2
Equi Equipm pmen entt rack rackss shou should ld be provided provided for mounting mounting line relays, automatic automatic synchroniz synchroniz-ing ing equi equipm pmen ent, t, the the comm common on and and outs outsid idee annu annunc ncia iato torr chassis, chassis, auxiliary auxiliary relays, relays, communicat communication ion equipment equipment,, and transf transfer er trip trip equipm equipment ent.. The equipmen equipmentt racks racks should should be standard, modular, vertical rack enclosures.
EM 1110-2-3006 30 Jun 94
8-3
EM 1110-2-3006 30 Jun 94 e. SCADA SCADA equipme equipment nt .
The The SCAD SCADA A and and comm commun uniication equipment should be located in the general control area.
8-5. Small Power Power Plant Contro Controll a. Genera Generall.
Small Small power plants plants using medium medium-vo -voltltage metalmetal-cla clad d switch switchgea gearr for genera generator tor contro controll impose impose differ different ent limita limitatio tions ns on equipm equipment ent arrang arrangeme ements nts than than arrang arrangeme ement nt limita limitatio tions ns of genera generator tor switch switchboa boards rds for local unit unit control. control. This is due to the variety of equipment equipment available with switchgear and, consequently, the different possib possibili ilitie tiess for locati locations ons for major major contro controll equipm equipment ent.. As noted in paragraph 8-1 g, hinged instrument panels on the main main switch switchgea gearr can be used used for contro controll equipm equipment ent.. Wher Wh eree spac spacee and and swit switch chge gear ar cons constr truc ucti tion on allo allow, w, it is desirable to have hinged instrument panels on the side of the stationary stationary structure structure opposite opposite the doors for removing removing the breaker breakers. s. These These panels panels,, howeve however, r, provid providee space space for only part of the necessary control equipment, and one or more auxiliary auxiliary switchgear switchgear compartments compartments will be required required to accommodate the remaining equipment. b. Equipme Equipment nt locatio location n.
Annunc Annunciat iator or window window panels, panels, indica indicatin ting g instru instrumen ments, ts, contro controll switch switches, es, and simila similarr equipm equipment ent should should be mounte mounted d on the switch switchgea gearr hinged hinged panels. panels. The hinged panel panel for each breaker section section should be assign assigned ed to the genera generatin ting g unit, unit, transm transmiss ission ion line, line, or statio station n servic servicee transf transform ormer er that that the breake breakerr serves serves and only only the indica indicatin ting g instru instrumen ments, ts, contro controll switch switches, es, etc., etc., associated with the controlled equipment mounted on the panel. panel. A hinged synchroniz synchronizing ing panel should should be attached attached to the end switchgear cubicle. c. Additio Additional nal equipm equipment ent locatio location n.
Protec Protectiv tivee relay relays, s, temperature indicators, load control equipment, and other equipment needed at the control location and not provided for on the switchge switchgear ar panels panels should should be mounte mounted d on the auxiliary switchgear compartments. d. SCADA SCADA equipme equipment nt . Smal Smalll powe powerr plan plants ts are frefrequently quently unattended unattended and remotely remotely controlled controlled from an offsite locatio location n using SCADA equipment equipment.. The SCADA and communica communication tion equipment equipment should should be located located in the general control area.
The applic applicati ation on of relays relays must must be coordi coordinat nated ed with with the partitioning of the electrical system by circuit breakers, so the least amount of equipment is removed from operation following following a fault, fault, preservin preserving g the integrity integrity of the balance of the plant’s electrical system. (1) Generally Generally,, the power transmittin transmitting g agency protection engineer will coordinate with the Corps of Engineers protectio protection n engineer engineer to recommend recommend the functional functional requirements of the overlapping zones of protection for the main transf transform ormers ers and high voltage voltage bus and lines. lines. The Corps Corps of Engineers Engineers protection protection engineer engineer will determine determine the protectio tection n requir required ed for the statio station n servic servicee genera generator torss and transformers, main unit generators, main transformers, and powerhouse bus. (2) Electromec Electromechanic hanical al protective protective relays, relays, individual individual solid solid state state protec protectiv tivee relays relays,, multimulti-fun functi ction on protec protecti tive ve relays, or some combination of these may be approved as approp appropria riate te for the requir requireme ements nts.. Tradit Tradition ional al electr electroomechanical protective relays offer long life but may malfunc functi tion on when when requ requir ired ed to oper operat ate, e, whil whilee many many less less popula popularr design designss are no longer longer manufact manufacture ured. d. Indivi Individua duall solid state protective protective relays relays and/or and/or multi-func multi-function tion protecprotective tive relays relays offer offer a single single soluti solution on for many many applic applicati ations ons plus continuous self diagnostics to alarm when unable to function function as required. required. Multi-fun Multi-function ction protectiv protectivee relays relays may be cost-competitive for generator and line protection when many many indivi individua duall relays relays would be requir required. ed. When When multimultifuncti function on relays relays are select selected, ed, limite limited d additi additiona onall backup backup relays should be considered based upon safety, the cost of equipm equipment ent lost lost or damage damaged, d, repair repairs, s, and the energy energy lost lost during the outage or repairs if appropriate. (3) When When the protec protectio tion n engine engineer er determ determine iness that that redundancy is required, a backup protective relay with a differ different ent design design and algori algorithm thm should should be provid provided ed for reliab reliabili ility ty and security security.. Fully Fully redund redundant ant protecti protection on is rarely justified even with multi-function relay applications. Generators Generators,, main transformer transformers, s, and the high voltage bus are are norm normal ally ly prot protec ecte ted d with with inde indepe pend nden entt diff differ eren enti tial al relays. (4) When the protective protective relays relays have been approved, approved, the protec protectio tion n engine engineer er will will provid providee or approv approvee the setsettings required for the application.
8-6. Protective Protective Relays b. Main gene generat rators ors. a. Genera Generall.
The follow following ing discuss discussion ion on protecti protective ve relays includes those devices which detect electrical faults or abnormal operating conditions and trip circuit breakers to isol isolat atee equi equipm pmen entt in trou troubl blee or noti notify fy the the oper operat ator or through through alarm devices devices that corrective corrective action action is required. required.
8-4
(1) The genera generall princi principle pless of relayi relaying ng practi practices ces for the genera generator tor and its excita excitatio tion n system system are discus discussed sed in IEEE standards C37.101, C37.102, and C37.106.
EM 1110-2-3006 30 Jun 94 Unless Unless otherwise otherwise stated, stated, recommenda recommendations tions contained contained in the above above guides guides apply apply to either either attend attended ed or unatte unattende nded d stations. (2) Differ Different ential ial relays relays of the high high speed, speed, percen percentag tagee differential type are usually provided to protect the stator windings of generators rated above 1500 kVA. (3) (3) A high high-i -imp mped edan ance ce grou ground nd usin using g a resi resist stan ance ce-loaded loaded distribut distribution ion transform transformer er scheme scheme is generally generally used, thereby limiting generator primary ground fault current to less less than than 25 A. A gene genera rato torr grou ground nd,, AC over overvo volt ltag agee relay with a third harmonic filter is connected across the grounding grounding impedance impedance to sense zero-sequen zero-sequence ce voltage. voltage. If the generator generator is sharing a GSU transformer transformer with another unit, a timed sequential ground relay operation to isolate and and loca locate te gene genera rato torr and and delt deltaa bus bus grou ground ndss shou should ld be provided. (4) Out-of-ste Out-of-step p relays relays are usually usually provided provided to protect generators connected to a 500- kV power system, because the complexi complexity ty of a modern modern EHV power power system system sometimes times leads leads to severe severe system system freque frequency ncy swings swings,, which which cause generato generators rs to go out of step. The generator generator out-ofout-ofstep step relays relays should should incorp incorpora orate te an offset offset mho and angle angle impedance impedance relay system system which can detect detect an out-of-st out-of-step ep condition when the swing locus passes through the generator or its transformer. (5) Frequency Frequency relays, and under- and over-frequ over-frequency ency protectio protection, n, are not required required for hydraulic hydraulic-turb -turbineine-drive driven n generators. (6) Temper Temperatu ature re relays relays are provid provided ed for thrust thrust and guide bearings as backup for resistance temperature detectors and indicating indicating thermomet thermometers ers with alarms. alarms. The relays o are set to operate at about 105 C and are connected to shut down down the unit. unit. Shutdown Shutdown at 105 105o C will not save the babbitt on the bearing but will prevent further damage to the machine. c. Generator Generator breakers breakers.
(1) Most breaker breaker failure relaying relaying schemes schemes operate on high high phase phase or groun ground d curr curren ents ts.. Wh When en a trip trip signa signall is applied to the breaker, the breaker should open and current rent flow flow should should cease cease within within the breake breakerr interr interrupt upting ing time. time. The breaker breaker failure relay relay is usually usually applied to operate lockou lockoutt relays relays to trip trip backup backup breake breakers rs after after a time time delay delay based based on the assumpti assumption on the breaker breaker has failed failed if curren currentt flow flow contin continues ues after after the breake breakerr trip trip circui circuitt has been energized energized.. These schemes schemes do not provide provide adequate adequate
protectio protection n if breaker breaker failure failure occurs occurs while current is near zero immediately following synchronizing. (2) Another Another scheme uses a breaker breaker auxiliary auxiliary contact to detect detect breake breakerr failur failuree with with fault fault detect detectors ors for phase phase curren currentt balanc balance, e, revers reversee power, power, and overcu overcurre rrent nt relays relays.. Prot Protec ecti tive ve rela relay y cont contac actt clos closin ing g or oper operat atio ion n of the the breake breakerr contro controll switch switch to the trip trip positi position on energi energizes zes a timing timing relay. relay. If the breaker breaker auxilia auxiliary ry contact contact does not close within the breaker interrupting time, the timing relay will close its contacts, enabling the phase current balance, reve revers rsee powe power, r, and and over overcu curr rren entt rela relays ys to perf perfor orm m the the required trip functions. (3) (3) Some Some brea breake kerr cont contro roll syst system emss moni monito torr the the breake breakerr trip trip coil coil using using a high high resist resistanc ancee coil coil relay relay conconnected nected in series series with the trip coil. coil. A time delay delay relay is required to allow the breaker to open during normal tripping without initiating an alarm. (4) Provision Provision should should be made to trip generator generator breabreakers kers when when there there is a loss loss of the breaker breaker trip circuit circuit DC control power or complete loss of DC for the entire plant. A stored energy capacitor trip device can be used to trip the breaker in case of a loss of control power. d. Transformer Transformer protection protection.
(1) Tra Transf nsform ormers ers or tran transf sfor orm mer ban banks over over 1500 kVA should should be protec protected ted with with high-s high-spee peed d percen percenttage-type age-type differential differential relays. relays. The basic principles principles involved in transformer protection are discussed in IEEE C37.91. (2) Separate Separate differential differential relay protection protection for generagenerators tors and transf transform ormers ers should should be provid provided ed even even on unit unit instal installat lation ionss withou withoutt a genera generator tor circuit circuit breaker breaker.. The relays applicable for generators can be set for much closer current balance than transformer differential relays. (3) (3) Auto Auto tran transf sfor orme mers rs can can be trea treate ted d as thre threeewindin winding g transf transform ormers ers and protec protected ted with with suitab suitable le highhighspee speed d diff differ eren enti tial al rela relays ys.. The The tert tertia iary ry wind windin ing g of an auto-t auto-tran ransfo sforme rmerr usuall usually y has a much much lower lower kVA rating than than the other other windin windings. gs. The current current transfo transforme rmerr ratios ratios should be based on voltage ratios of the respective windings ings and and all all wind windin ings gs cons consid ider ered ed to have have the the same same (highest) kVA rating. (4) Therma Thermall relays relays supple supplemen mentt resist resistanc ancee temper temperaature detectors detectors and thermomete thermometers rs with alarm contacts. contacts. The relays are set to operate when the transformer temperature reac reache hess a poin pointt too too high high for for safe safe oper operat atio ion, n, and and are are
8-5
EM 1110-2-3006 30 Jun 94 connec connected ted to trip trip breake breakers rs unload unloading ing the transf transform ormers ers.. These These relays relays are import important ant for forced forced-oi -oill waterwater-coo cooled led tran transf sfor orme mers rs whic which h may may not not have have any any capa capaci city ty rati rating ng without cooling water.
system system,, speed speed of operat operation ion requir required ed to mainta maintain in system system stability stability,, coordinati coordinating ng character characteristi istics cs with relays relays on the other end of the line, and the PMA or utility system operating requiremen requirements. ts. The basic principles principles of relaying practices are discussed in IEEE C37.95.
e. Bus prot protect ection ion. h. Shutdo Shutdown wn relays relays.
(1) High-v High-volt oltage age switch switchyar yard d buses buses can be protec protected ted with with bus bus prot protec ecti tion on,, but but the the nece necess ssit ity y and and type type of bus bus protection depends on factors including bus configuration, relay input sources, and importance of the switchyard in the transmis transmissio sion n system system.. Applic Applicati ation on of bus protec protectio tion n should be coordinated with the PMA or utility operating agency. agency. The basic principle principless of bus protectio protection n operation operation are discussed in IEEE C37.97.
The The shut shutdo down wn locko lockout ut relay relayss stop the unit by operating shutdown equipment and tripping ping circui circuitt breake breakers. rs. The lockout lockout relay relay operat operation ionss are usuall usually y divide divided d into into two groups. groups. A genera generator tor electri electrical cal lockout relay, 86GX, is initiated by protective relaying or the the oper operat ator or’s ’s emer emerge genc ncy y trip trip swit switch ch.. The The gene genera rato torr mech mechan anic ical al lock lockou outt rela relay, y, 86GM 86GM,, is trig trigge gere red d by mechanical troubles, such as bearing high temperatures or low low oil oil pre pressur ssure. e. The The unit unit shut shutdo down wn seque equenc ncee is described in IEEE 1010.
(2) Large power power plants with a complex station station service service system system config configura uratio tion n should should be provid provided ed with with statio station n service switchgear bus differential relay protection.
8-7. Automatic Automatic Generation Generation Control Control (AGC)
(3) A ground ground relay relay should should be provid provided ed on the deltadeltaconn connec ecte ted d buse busess of the the stat statio ion n serv servic icee swit switch chge gear ar.. A voltag voltagee relay, relay, connec connected ted to the broken broken-de -delta lta potent potential ial transf transform ormer er second secondary ary windin windings, gs, is usuall usually y provid provided ed to detect detect grounds grounds.. A loadin loading g resist resistor or may be placed placed across across the broken delta delta to prevent prevent possible possible ferroresonan ferroresonance. ce. The ground detector usually provides only an alarm indication. f. Feeder protection.
Feeder Feeder circu circuits its that that operat operatee at main generator voltage and 4160-V station service feeders should be protected with overcurrent relays having instantaneou taneouss trip trip units and a ground ground relay. relay. The settin setting g of the ground relay should be coordinated with the setting of the generator ground relay to prevent shutdown of a generator due to a grounded feeder. g. Transmissio Transmission n line protection protection. Rela Relays ys for for the pro pro-tectio tection n of transm transmiss ission ion lines lines should should be select selected ed on the basis of dependability of operation, selectivity required for coordi coordinat nation ion with with existi existing ng relays relays on the interc interconn onnect ected ed
8-6
For comput computerer-bas based ed contro controll system systems, s, unit unit load load can be contro controlle lled d in accord accordanc ancee with with an error error signal signal develo developed ped by digit digital al comput computers ers period periodica ically lly sampli sampling ng real real power power flow over the tie line, line frequency, and generator power output. output. These analog analog signals are continuous continuously ly monitored monitored at the the load load disp dispat atch ch cont contro roll cent center er to obta obtain in the the plan plantt generation generation control control error. The control error digital digital quantity is transmitted via telemetry to each plant and allocated to the units units by the comput computerer-bas based ed plant plant contro controll system system.. AGC acti action on by the the plan plantt cont contro roll syst system em conv conver erts ts the the raise/ raise/low lower er megawa megawatt tt signal signal into into a timed timed relay relay contac contactt closure closure to the governor. governor. The governor governor produces produces a wicket gate open/close movement to change the generator output power. power. Other Other modes modes of operatio operation n includ includee set point point control, trol, regula regulatin ting, g, base base loaded loaded,, ramped ramped contro control, l, manual manual control, and others relative to the nature of the project and operat operating ing philos philosoph ophy. y. Coordi Coordinat nation ion of the engine engineeri ering ng planni planning ng of the AGC with with the market marketing ing agency agency should should begin at an early stage.
EM 1110-2-3006 30 Jun 94
Chapter 9 Annunciation Annunciation Systems
9-3. Annunciator Annunciator
9-1. 9-1. Genera Generall EPRI EPRI EL-5 EL-503 036, 6, Volu Volume me 10, 10, prov provid ides es guid guidel elin ines es and and consid considera eratio tions ns in planni planning ng and design designing ing annunc annunciat iation ion systems for power plants.
9-2. 9-2. Audio Audio and Visual Visual Signals Signals Every power plant should be provided with an annunciation system providing providing both audible audible and visual visual signals signals in the event of trouble or abnormal conditions.
a. Genera Generall. The The annun nnuncciat iator syst ystem shou shoulld be designed for operation on the ungrounded 125-V DC system discu discusse ssed d in Chapter Chapter 11. 11. All remot remotee contac contacts ts used used for trouble annunciation should be electrically independent of contacts used for other purposes so annunciator circuits are separat separated ed from from other other DC circui circuits. ts. Auxili Auxiliary ary relays relays should should be provid provided ed where where electr electrica ically lly indepe independe ndent nt concontact tactss cann cannot ot othe otherw rwis isee be obta obtain ined ed.. The The annu annunc ncia iato torr equipm equipment ent should should use solidsolid-sta state te logic logic units, units, lighte lighteddwindow or LED type, designed and tested for surge withstandi standing ng capabi capabilit lity y in accord accordanc ancee with with ANSI ANSI C37.90 C37.90.1, .1, and manufactur manufactured ed in accordance accordance with ANSI/ISA ANSI/ISA S18.1. b. The switchboard switchboard annunciator annunciator operational operational sequence sequence
a. Audi Audio o sign signal alss.
should be a manual or automatic reset sequence as listed in Table 9-1.
b. Visu Visual al sign signal alss.
Automatic reset should be employed when there is either an SER or a SCADA SCADA system system backup. backup. When When the plant plant is controlled and dispatched through the SCADA system of the the whee wheeli ling ng util utilit ity, y, the the desi design gn rese resett feat featur ures es of the the annu annunc ncia iato torr shou should ld be coor coordi dina nate ted d to ensu ensure re prop proper er operation.
Howl Howler er horns horns and and inte interm rmit itte tent nt gongs are used for audible audible signal devices. devices. An intermitte intermittent nt gong is provided provided in the plant control control room. room. Howler horns horns are are used used in the the unit unit area area and and in area areass wher wheree the the back back-ground noise is high (e.g., in the turbine pit) or in areas remote from the unit (e.g., plant switchyard). Visu Visual al signa signals ls are provi provide ded d by ligh lighte ted d lett letter ered ed wind window ow pane panels ls of the the annu annunc ncia iato tor. r. In larg larger er plan plants ts,, the the annu annunc ncia iato torr pane panell indi indica cati tion on is augm augmen ente ted d by unit unit trou troubl blee lamp lampss loca locate ted d in a read readil ily y visibl visiblee positi position on close to the unit. unit. The plant plant sequen sequence ce of events events recorder recorder (SER) is normally normally located in the control room. Separate Separate annunciator annunciatorss (when provided) provided) for station servic servicee system systemss and switch switchyar yards ds should should be locate located d on associated control panels of the station service switchgear or on the switchyard control panels.
c. The The
gene genera rato torr swit switch chbo boar ard d is prov provid ided ed with with annunc annunciat iator or alarm alarm points points for unit unit emerge emergency ncy shutdo shutdown, wn, generator generator differenti differential al lockout, lockout, generator generator incomplete incomplete start, start, gene genera rato torr or 15-k 15-kV V bus bus grou ground nd,, gene genera rato torr over oversp spee eed, d, generator overcurrent, generator breaker low pressure, unit contro controll power power loss, loss, genera generator tor CO2 powe powerr off, off, PT fuse fuse failure or undervoltage, and head cover high water.
Table 9-1 Switchboard Annunciator Operational Sequence
Field Contact
Control Pushbutton or Switch
Alarm Lights
Horn
Auxiliary or Repeater Contacts
Normal
--
Of f
Off
Off
Flashing
On On
On
Abnormal Abnormal
Acknowledge or Silence
On
Off
On
Normal
Reset
Of f
Of f
Off
Normal
Test
On
Of f
Off
9-1
EM 1110-2-3006 30 Jun 94 Cert Certai ain n alar alarm m poin points ts have have seve severa rall trou troubl blee cont contac acts ts in parallel parallel by equipment group. group. Examples Examples include include generator exci excita tati tion on syst system em trip trip or trou troubl ble, e, turb turbin inee bear bearin ing g oil oil trouble, trouble, generator generator cooling water flow, unit bearing bearing overheat, generator oil level, generator stator high temperature, and governor oil trouble.
window indicating light annunciator provides backup for a sequential sequential event event recorder. recorder. Unit switchboar switchboard d annunciator annunciator remote remote contro controll switch switches es to silenc silencee and reset reset the switch switch-boar board d annu annunc ncia iato torr shou should ld be prov provid ided ed on the the cont contro roll console.
9-4. Sequence Sequence of Events Events Recorder Recorder (SER) d . The generato generatorr switch switchboa board rd may be provid provided ed with with
an additional additional annunciator annunciator for the generator step-up step-up transtransformer and unit auxiliary equipment alarms, depending on the plant arrangeme arrangement. nt. Generally Generally,, these alarm points points are transform transformer er different differential, ial, transforme transformerr lockout lockout trip, trip, transtransformer former overheat, overheat, transforme transformerr trouble, trouble, 480-V switchgear switchgear trip, and trouble. e. The genera generator tor excita excitatio tion n cubicl cubiclee is provid provided ed with with
an annunciator annunciator for excitatio excitation n equipment equipment alarm points for AC regula regulator tor trip, trip, bridge bridge overte overtempe mperat rature ure,, transf transform ormer er over temperatur temperature, e, regulator regulator power supply, field field overvoltovervoltage, maximum excitation limit, minimum excitation limit, and volt per Hertz. Generator Generator overvolta overvoltage, ge, power system stabilizer, and fan failure alarm points should be included when required. f . The switchboard switchboard annuncia annunciator tor for large power plants plants should be provided with auxiliary or repeater contacts to drive drive contro controll room room consol consolee remote remote annunc annunciat iator or wordwordindicating lights. g. A control control console window-indica window-indicating ting light annun-
ciator ciator is common common to all units. units. One unit unit at a time time can be sele select cted ed by use use of the the appr approp opri riat atee unit unit trou troubl blee stat status us lighte lighted d pushbu pushbutto tton. n. Visual Visual indicati indication on is provid provided ed when when the unit switchbo switchboard ard annuncia annunciator tor is activa activated ted.. The console sole window window indica indicatin ting g lights lights are genera generally lly groupe grouped d by switch switchboa board rd annunc annunciat iator or points points and provid providee essent essential ial trouble trouble status to the operator. operator. Unit troubles troubles are normally normally categorized by shutdown, differential, overcurrent, cooling wate water, r, bear bearin ing g oil, oil, unit unit trou troubl ble, e, brea breake kerr air, air, CO2 discharge charge,, contro controll power, power, and head head cover cover high water. water. The
An SER SER shou should ld be prov provid ided ed to comp comple leme ment nt the the plan plantt annunciation system if a SCADA system is not performing the sequence sequence of events events function. function. The SER provides provides a time-tagg time-tagged, ed, sequenced, sequenced, printed record record of trouble trouble events. events. The documented record of a trouble event aids in diagnosing power plant plant forced outages. outages. It is designed designed for operation tion on an ungrou unground nded ed 125-V 125-V DC syst system em.. All All inpu inputs ts should be optically isolated and filtered for 125-V DC dry contac contactt change change-of -of-st -state ate scannin scanning. g. The SER minimu minimum m resolutio resolution n should be coordinated coordinated with using using agencies. agencies. A value value of 2 msec msec is typica typical. l. When When an input signal signal status status change occurs, the SER should automatically initiate and prod produc ucee a tabu tabula late ted d prin printe ted d reco record rd on the the data data logg logger er iden identi tify fyin ing g the the even eventt and and show showin ing g the the time time of stat status us change change (to the nearest nearest millise millisecon cond). d). The SER should should be provid provided ed with with a system system clock clock and time time synchr synchroni onizat zation ion featur features. es. Each Each SER system system should should be provid provided ed with an adequate input point capacity to monitor each alarm trouble contact and provide plant breaker status necessary for the plant operati operation. on. The alarm alarm troubl troublee contac contacts ts should should include IEEE 1010 requirements and project alarm points requirements.
9-5. Trouble Trouble Annunciator Annunciator Points Points All of the alarm points listed in Table 9-2 below are not required in every plant, and, conversely, requirements for an unlist unlisted ed alarm point point may arise. arise. IEEE IEEE 1010 1010 provides provides types of alarm signals transmitted to the generator annunciator ciator from from the genera generator tor,, excita excitatio tion n system system,, genera generator tor terminal terminal cabinet, cabinet, generator generator breaker, breaker, step-up step-up transform transformer, er, turbine, and governor, which are listed in Table 9-2.
Table 9-2 Alarm Signals Transmitted to the Generator Annunciator Generator Switchboard Annunciator Points Signal
Description
86GX & 86GT 87GX 48TDC 64X 12G 51GAR 63
Unit Emergency Shutdown Generator Differential Shutdown Generator Incomplete Start Generator or 15-kV Bus Bus Ground Generator Overspeed Generator Overcurrent Generator Breaker Low Pressure (Continued)
9-2
EM 1110-2-3006 30 Jun 94 Table 9-2. 9-2. (Continued) (Continued) Generator Switchboard Annunciator Points Signal
Description
74CB 63X 27CO2 27G 71HC * * * * * * *
Control Power Loss CO2 Discharge CO2 Power Off PT Fuse Fail or Undervoltage Head Cover High Water Generator Regulator Trip or Trouble Turbine Bearing Oil Trouble Generator Cooling Water Flow Unit Bearing Oil Trouble Generator Oil Level Generator Stator High Temperature Governor Oil Trouble * See IEEE 1010 Step-Up Transformer Annunciation Points
Signal
Description
87TAR 86L 74TL * * 20TDX
Transformer Transformer Transformer Transformer Transformer Transformer
Differential Lockout Trip (Includes Transformer Ground) Control Power Loss Overheat Trouble Deluge * See IEEE 1010 Line Annunciation Points
Signal
Description
94L1 74 74
Line Lockout Line Relay or MW Power Off Microwave Trouble Station Service Transformer Annunciation Points
Signal
Description
86T 63G,49,26Q,71Q 94 63X
Transformer Lockout Transformer Trouble Transformer Breaker Tripped CO2 Discharge Station Annunciation Points
Signal
Description
86BD BA
Station Service Switchgear Bus Differential Station Service Switchgear DC Trouble Station Annunciation Points
Signal
Description
63 94
Station Service Switchgear Breaker Low Pressure Station Service Feeder Breaker Tripped (Continued)
9-3
EM 1110-2-3006 30 Jun 94 Table 9-2. 9-2. (Concluded) (Concluded) BA 64,BA 74 BA 64,74,27 64,74,27 BA 74,83 71 71 71 71 63 63 27 42 74,71 94 74
480-V AC Feeder Breaker Tripped Bus Tie Breaker Tripped or Trouble Battery Charger Failure 125-V DC Feeder Breaker Tripped 125-V DC System Tripped 48-V DC System Trouble 48-V DC Feeder Breaker Trip Inverter Trouble Unwatering Pump Trouble Drainage Pump Trouble Septic Tank High Level Effluent High Level Station Air Low Pressure Oil or Paint Storage Room CO2 Discharge Fire Pump Power Off Fire Pump On Engine Generator Trouble Engine Generator Trip Plant Intrusion Detector Switchyard Annunciation Points
Signal
Description
63 63 27 27 86 27 21 50/51L 64L 94L 74 86BD 74 42 49 71G 71Q 63Q 51G 63G 86T 87T 50/51T
Power Circuit Breaker Loss of Tripping and Closing Energy Power Circuit Breaker Energy Storage System Energy Breaker Close Bus Failure Breaker Trip Bus Failure Breaker Failure Lockout Relay Relay Potential Failure Line Distance Relay Trip Line Overcurrent Relay Trip Line Ground Relay Trip Microwave Transfer Trip MWTT Trouble Bus Failure Lockout Relay Line Communication Trip Transformer Cooling Fan Failure Transformer Overheat Transformer Gas Accumulator Transformer Oil Level Transformer Sudden Pressure Relay Transformer Ground Detector Transformer Inert Air Tank Pressure Transformer Lockout Relay Transformer Phase Differential Transformer Phase Overcurrent Switchyard Annunciation Points
Signal
Description
50G 28 74 27,64,74 74,83 42 71,74 74
Transformer Neutral Overcurrent Transformer Fire Battery Charger Trouble Battery Trouble Inverter Trouble Engine Generator Running Engine Generator Trouble Yard Intrusion Detector
9-4
EM 1110-2-3006 30 Jun 94
Chapter 10 Communication Communication System
control control room. A preferred preferred AC circuit should should be provided for the commercial equipment. c. Telepho Telephone ne locatio locations ns.
10-1. 10-1. Genera Generall a. Types Types of system systemss availab available le. Reliab Reliable le commun communica ica-tion tion syst system emss are are vita vitall to the the oper operat atio ion n of ever every y powe powerr plant. plant. Voice Voice communic communicati ation on is a necess necessity ity at all plants plants and code-call signaling is generally required for accessing person personnel nel at large large power power plants. plants. Additi Additiona onall dedica dedicated ted commun communica icatio tion n system systemss are requir required ed for teleme telemeter tering ing,, SCADA SCADA,, and and for for cert certai ain n type typess of prot protec ecti tive ve rela relayi ying ng.. Communications media available for power plant application include: metallic metallic cable pairs; leased telephone telephone lines; power power line line carrie carrierr (PLC); (PLC); radio radio freque frequency ncy commun communica ica-tions, including two-way land mobile (TWLM) radio and terres terrestri trial al microw microwave ave ( MW ); ) ; fibe fiberr opti optics cs;; and and sate satell llit itee communications. b. Regulatory Regulatory requirem requirements ents. The Federa Federall Informat Information ion
Resource Resource Managemen Managementt Regulatio Regulation n (FIRMR), (FIRMR), as adminisadministered tered by the Genera Generall Servic Services es Admini Administr strati ation on (GSA), (GSA), requir requires es GSA approv approval al for all commun communica icatio tion n system systemss (oth (other er than than mili milita tary ry)) used used by agen agenci cies es of the the Fede Federa rall Govern Governmen ment. t. The GSA contra contract ct with common common carrie carriers rs guarantees guarantees carriers carriers access access to Government Government long-dist long-distance ance commun communica icatio tion n busine business. ss. The service service to provid providee longlongdist distan ance ce comm commun unic icat atio ions ns is know known n as FTS FTS 2000 2000.. The The GSA requires its use by Government agencies, unless the agenci agencies es are able to prove, prove, on a case-b case-by-c y-case ase basis, basis, that that the FTS 2000 servic servicee will will not meet meet its needs. needs. For inforinformati mation on on the the FIRM FIRMR, R, and and appr approv oval al docu docume ment ntat atio ion n needed, contact the Corps of Engineers Information Management Office.
10-2. Voice Communica Communication tion System System a. Teleph Telephone one service service. Normal Normally, ly, general general intern internal al and external external telephone telephone communica communications tions are provided provided through through public public switched switched telephone telephone network network services services installed installed and operat operated ed by the serving serving telepho telephone ne compan company. y. The equipequipment (including (including telephones telephones)) is leased leased from the telephone telephone comp compan any. y. The The comm commun unic icat atio ion n circ circui uits ts prov provid ided ed by a commercial telephone operating company include connection tion to local local exchan exchange, ge, long long distan distance, ce, WATS, WATS, and FTS 2000 telephone telephone service. service. Telephone Telephone pay stations stations in visitor visitor areas should be provided for public convenience. b. Plan Plantt equi equipm pmen ent t .
The The dis distrib tribu uting ting frame rame and switching switching equipment equipment for any commercia commerciall systems systems should should be installed in a location near the control room where it can can be incl includ uded ed in the the air air cond condit itio ioni ning ng zone zone for for the the
To ensur ensuree adeq adequa uate te tele tele-phone access, sufficient sufficient telephone telephone outlets should be provided vided in the office office area, area, the contro controll room, room, the genera generator tor floor at each unit, the switchgear area, the station service area area,, and and the the plan plant’ t’ss repa repair ir shop shops. s. A tele teleph phon onee outl outlet et shou should ld be prov provid ided ed in each elevat elevator or cab. Circ Circui uits ts to teleph telephone one outlet outletss are provid provided ed by metall metallic ic cable cable pairs. pairs. Teleph Telephone one wiring wiring inside inside the plant, plant, from from the teleph telephone one company switching equipment location to the location of the variou variouss instru instrumen ments, ts, is provid provided ed by the Govern Governmen mentt and include included d in the powerho powerhouse use design. design. Embedd Embedded ed conconduit duitss dedi dedica cate ted d to tele teleph phon onee use use are are prov provid ided ed for for the the cables.
10-3. Dedicated Dedicated Communications Communications System System a. Genera Generall.
Dedicated Dedicated communi communicati cations ons systems systems are provided in the plant for code call systems, SCADA systems, protective relay systems, and for voice communications tions to the dispat dispatchi ching ng center centerss and substa substatio tions ns of the power wheeling wheeling entity entity (either Federal Federal Power Marketin Marketing g Agency Agency (PMA) or non-Federa non-Federall utility). utility). Communica Communications tions media for performing these functions can be either leased commerci commercial al circuits, circuits, power line carrier (PLC), radio frequency quency communica communications tions,, fiber-opt fiber-optic ic cable, cable, satellit satellitee communications, or a combination of these media. b. Code Code call system system. Genera Generally lly,, code-c code-call all facilit facilities ies are provided at all plants permitting paging of key personnel. nel. A separa separate, te, Governme Governmentnt-own owned ed code-c code-call all system system should should be provid provided ed when when leased leased teleph telephone oness are used, used, so maintenance of the code call will not depend on outside person personnel nel.. An automa automatic tic repeatin repeating g type type code-s code-send ending ing station station should be located located on the control room operator’ operator’ss desk or console. c. Utility telepho telephone ne systems systems.
(1) Voice communicat communications ions facilities facilities for power plant control and dispatch use are typically provided through a utility utility or Federal PMA-owned PMA-owned telephone telephone system. system. If it is a Federa Federally lly owned owned system system,, the FIRMR FIRMR requir requires es the use of FTS2000 for inter-local access and transport area service, unless unless an exceptio exception n is granted granted.. In some instanc instances, es, the major major use of the commun communica icatio tion n channe channell has been the determini determining ng factor factor in whether whether Government Government ownership ownership of the system system is permitted. permitted. If the major use of the service service is technical; that is, plant operating and control information, then Government ownership has been approved.
10-1
EM 1110-2-3006 30 Jun 94 (2) The teleph telephone one system system should should provid providee access access to dispatchin dispatching g voice channels channels of the utility. utility. Generally Generally,, dial automatic telephone switching facilities provide a systemwide wide networ network k of voice voice circui circuits ts which which are automa automatic ticall ally y switch switched ed to permi permitt callin calling g betwee between n genera generatin ting g statio stations, ns, major major substations, substations, and control centers. centers. Some plants plants have used leased private private line service for communica communication tionss circuits which are provided by a commercial telephone company pany’s ’s comm common on carr carrie ierr for for the the sole sole use use of the the plan plant. t. These circuits are provided on the cable and other transmissio mission n facili facilitie tiess of the carrie carrier, r, but should should not be conconnected nected direct directly ly to the networ network k switch switching ing system systemss of the carrier or telephone operating company. d. Leased Leased circ circuits uits.
(1) Leased Leased commercial commercial circuits circuits can be used for voice communica communication tion circuits circuits as described described in paragraph paragraph 10-3 c. Voice grade communication channels are required and are supplied either through a dial or a dedicated system, with dedica dedicated ted channe channels ls being being the prefer preferred red alternat alternative ive.. The basic basic voicevoice-ban bandwi dwidth dth privat privatee line line channe channell is an AT&T AT&T system system “Type 3002 unconditio unconditioned” ned” channel. channel. Other comcommerciall mercially y available available private line data channel services services are Digi Digita tall Data Data Serv Servic icee (DDS (DDS)) and and Basi Basicc Data Data Serv Servic icee (BDS). (BDS). These latter latter services services offer digital interconne interconnectivctivity through a wide range of data transmission speeds. (2) Leased Leased circuits circuits have been been used used for plant protecprotective relaying relaying circuits circuits with with mixed results. results. Generally, Generally, it is better to own the communication facility if it is used for vital vital high-speed high-speed relaying relaying service. service. Some of the past problems lems with with leas leased ed chan channe nels ls have have been been loss loss of serv servic icee beca becaus usee of unan unanno noun unce ced d main mainte tena nanc ncee acti activi vity ty by the the leasin leasing g agency agency,, failur failuree of the system system,, rerout rerouting ing of the service service because because of maintenanc maintenancee or constructi construction on activity, activity, and accidenta accidentall circuit circuit interrupti interruption on by personnel personnel looking for for trou troubl blee on othe otherr circ circui uits ts.. Typi Typica call lly, y, a leas leasin ing g agency agency’s ’s operat operating ing and mainte maintenan nance ce person personnel nel do not understan understand d the level of reliabili reliability ty necessary necessary for relaying relaying circuits. (3) Leased Leased circuit circuitss have have been been used used for SCADA system tem cont contro roll of plan plants ts and and subs substa tati tion ons. s. Here Here,, too, too, the the result resultss have have been been mixed. mixed. For short short distan distances ces where where the leasing agency can provide a direct link between the local and remote remote station station,, result resultss have have been been good. good. Where Where the circuit has been routed through a central office, the reliability of service has in a number of cases not been of the level of reliability needed for data acquisition and control. The lack of reliability is apt to be more of a problem if the plant is in a remote location and served by a small tele teleph phon onee comp compan any. y. Use Use of leas leased ed faci facili liti ties es has has to be
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consid considere ered d on a case-b case-by-c y-case ase basis, basis, and all of the influinfluencing factors need to be considered, including the service record of the proposed leasing agency. e. Power Power line carri carrier. er.
(1) A “basic “basic”” PLC system system consis consists ts of three three distin distinct ct parts: (a) The terminal terminal assemblies, assemblies, consisting consisting of the transtransmitters, receivers, and associated components. (b) The coupling coupling and tuning tuning equipmen equipment, t, which which proprovides vides a means means of connec connectin ting g the PLCs termin terminals als to the high-voltage transmission line. (c) The high-v high-volt oltage age transm transmiss ission ion line, line, which which proprovide videss the the path path for for tran transm smis issi sion on of the the carr carrie ierr ener energy gy.. High-volta High-voltage ge coupling coupling capacitors capacitors are used to couple couple the carrier energy to the transmission line, and simultaneously block 60-Hz power from the carrier equipment. (2) Most transmitt transmitter/r er/receiv eceiver er equipment equipment is installed installed in standard 19-in. radio racks inside cabinets located near the plant control control room. Carrier Carrier frequency frequency energy energy is conducted out of the plant by coaxial cable to the high-voltage transm transmiss ission ion line line tuning tuning and coupli coupling ng equipm equipment ent.. PLC equipm equipment ent power power requir requireme ements nts are suppli supplied ed from from either 48-V or 125-V DC derived from the station battery or a dedica dedicated ted communi communicat cation ionss batter battery y source source.. If a PLC system is to be provided, routing provisions for the wire and cables needed must be included in the plant design. (3) Power line carrier communicat communication ion systems have found extensive use for relaying, control, and voice communications in Europe, and in some areas of the United Stat States es.. Thei Theirr use use is less less popu popula larr in the the Unit United ed Stat States es,, apparently apparently because of the availabil availability ity of radio frequency frequency spectrum, and utility-owned communication systems apart from the power transmissi transmission on facilities. facilities. PLC bandwidth bandwidth is limited because of its operating frequencies and the transmissio mission n medium medium.. Its transmis transmissio sion n path path is suscep susceptib tible le to noise from arcing faults, interruption by ground faults and other accidents accidents to the line, and weather. weather. If other reliable reliable communica communication tion means are available available at a reasonabl reasonablee cost, it would would probab probably ly be advant advantage ageous ous to avoid avoid the use of PLC. f. TWLM radio.
(1) There There is some some very very limite limited d use of TWLM TWLM radio radio in SCAD SCADA A syst system emss usin using g the the 150150-MH MHzz and and 450450-MH MHzz freque frequency ncy bands. bands. Mostly Mostly,, it is used used for data data links links with
EM 1110-2-3006 30 Jun 94 small small distributi distribution on system system remote remote terminal terminal units (RTUs) that that are not critic critical al to power power system system operatio operation n and not economical to serve with a dedicated or dial phone line. More More comm common on usag usagee of TWLM TWLM medi mediaa is Mult Multip iple le Addr Addres esss Syst System em (MAS (MAS)) radi radio, o, whic which h was was deve develo lope ped d specifically for SCADA applications. (2) MAS essent essential ially ly emulat emulates es teleph telephone one leased leased line line circui circuits. ts. The system system consists consists of a transm transmitt itting ing master master station station and multiple multiple remote stations stations using frequenci frequencies es in the 900-MHz 900-MHz and above range. range. Its use is not practical practical for for hydro plant data acquisition and control, but it should be considere considered d if a hydromete hydrometeorolo orologica gicall (hydromet (hydromet)) data system tem is to be buil builtt in the the plan plantt area area,, and and hydr hydrom omet et data data gath gather erin ing g cont contro roll lled ed from from the the plan plant. t. It coul could d also also be consid considere ered d for use in pumpin pumping g plants plants that are under the surveilla surveillance nce of the plant staff. g. Microw Microwave ave radio radio..
(1) Microwave Microwave radio consists consists of transceiv transceivers ers operating operating at or above 1,000 MHz in either a point-to-point or pointmultip multipoin ointt mode. mode. Microw Microwave ave radio radio system systemss have have both both multip multiple le voice voice channe channell and data data channe channell capabi capabilit lities ies.. Microwave systems use either analog (Frequency Division Multip Multiplex lex [FDM]) [FDM]) or digita digitall (Time (Time Divisi Division on Multip Multiplex lex [TDM [TDM]) ]) modu modula lati ting ng tech techni niqu ques es.. The The tren trend d is towa toward rdss digital modulating systems because of increasing need for high high speed speed data data circui circuits ts and the superi superior or noise noise perfor perfor-mance mance of TDM modulat modulation ion.. Analog Analog radio radio is consid considere ered d to be obso obsole lete te tech techno nolo logy gy,, and and it is like likely ly that that anal analog og radio will not be available in the future. (2) Microw Microwave ave radio energy energy is transm transmitt itted ed in a “line “line of sight” to the receiving station, and the useful transmission sion path path leng length th vari varies es depe depend ndin ing g on the the freq freque uenc ncy. y. Whether a microwave system can be used at all depends on factors beyond the scope of this manual, including the terrai terrain n featur features es between between end points points of the system. system. HowHowever, in general it can be said that useful systems of any length will require one or more repeater stations located at such points on the radio path that they can be seen from the stations they receive from, and the stations they transmit to. Such Such repeat repeater er locatio locations ns may be remote remote from from any utility services, and in fact may not even be near a road. Site Site access access,, real real estate estate acquis acquisiti ition, on, constr construct uction ion on the site, site, environme environmental ntal impacts, impacts, and maintenan maintenance ce of the station tion need need to be carefu carefully lly consid considere ered d before before a final final decidecision is made to use microwave microwave communicatio communications. ns. FIRMR requirements must also be considered. (3) Microwave Microwave radio radio has found some short-ra short-range nge use in providing communication between the powerhouse and
its switchyard, if the switchyard is located a mile or more away away from from the the plan plantt and and the the plan plantt grou ground nd mat mat is not not soli solidl dly y conn connec ecte ted d to the the subs substa tati tion on grou ground nd mat. mat. The The dang danger er of volt voltag agee rise rise on cont contro roll and and comm commun unic icat atio ion n cables cables betwee between n plant plant and substa substatio tion n during during fault fault condicondition tionss is well well know known. n. Micr Microw owav avee radi radio o is part partic icul ular arly ly useful here in providing isolation from noise and dangerous voltage levels on these circuits, since with the radio there there is no metall metallic ic connec connectio tion n betwee between n the termin terminals als.. Note, however, that a fiber-optic carrier system will also offer the advantages of a nonmetallic connection, and may be more economical. (4) Genera Generally lly,, microw microwave ave radio radio transc transceiv eiver er equipequipment ment acco accomm mmod odat atio ions ns in the the plan plantt are are hand handle led d in the the same manner manner as PLC equipment accommo accommodatio dations. ns. However, distance to the antenna, antenna location, and wave guide routing routing must be considered considered.. The effects effects of icing icing on the antenna may require a power source for the antenna location to provide antenna heating. h. Fiber-optic Fiber-optic cable.
(1) A fiber-optic fiber-optic cable system system consists consists of a terminal with with mult multip iple lexi xing ng equi equipm pmen ent, t, and and a tran transm smit itte terr and and receiv receiver er couple coupled d to fiberfiber-opt optic ic light light conduc conductor torss that that are routed routed to the other termin terminal, al, which also also has a receiv receiver, er, transm transmitt itter, er, and multip multiplex lexing ing equipmen equipment. t. Becaus Becausee the transmis transmission sion medium is nonmetalli nonmetallic, c, it offers offers the advanadvantage of electrical electrical isolation isolation between between terminals terminals and immuimmunity from electromagnetic interference. (2) (2) Beca Becaus usee of the the freq freque uenc ncy y of the the tran transm smit itti ting ng medium, medium, light, light, the fiber-opti fiber-opticc system system offers offers a bandwidth bandwidth that that can carry carry a great great deal of data at very high high speeds speeds.. The The glas glasss fibe fibers rs are are smal smalll and and deli delica cate te,, so shou should ld be enclosed enclosed in a protectin protecting g sheath. For communicati communication on systems external to the plant, right-of-way acquisition may be a problem since the fiber-optic cable does require routing just as a copper cable would. (3) (3) Ther Theree are are many many poss possib ible le ways ways of rout routin ing g the the fiber. fiber. It is possib possible le to obtain obtain high-vol high-voltag tagee transm transmiss ission ion line cable with fiber-optic light conductors incorporated in its construct construction. ion. The fiber-opti fiber-opticc light conductor conductor can also be underbui underbuilt lt on the transm transmiss ission ion line to the plant. plant. For long long tran transm smis issi sion on dist distan ance ces, s, the the fibe fiberr-op opti ticc syst system em requ requir ires es repe repeat ater ers. s. The The tran transm smis issi sion on dist distan ance ce befo before re repeaters are needed has been steadily increasing because of the developm development ent effort effort in this this techno technolog logy. y. It offers offers great possibilitie possibilitiess for external external plant communicatio communication n systems and should be considered in each case.
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EM 1110-2-3006 30 Jun 94 (4) Probably Probably the most important important applicatio application n for fiberopti opticc tech techno nolo logy gy is for for a Loca Locall Area Area Netw Networ ork k (LAN (LAN)) within within the plant. Its large large data capacity, capacity, high rate of data transmiss transmission ion speed, speed, and immunity immunity from electroma electromagneti gneticc interference make the LAN an ideal medium for communicati nication on among among the elemen elements ts of distri distribut buted ed contro controll syssystems tems within within the plant. plant. The technol technology ogy is develo developin ping g at a very rapid rate, and standards are coming into being, such as the Fiber Distribute Distributed d Data Interface Interface (FDDI), (FDDI), allowing allowing its use with a variety of devices. i. Satellite Satellite communications communications. Satellit Satellitee communi communicati cation on systems have not been applied to Corps plants because of cost cost and and conv conven enie ienc nce. e. The The Corp Corpss has has made made use use of a satell satellite ite time time signal signal to provid providee a unifor uniform m time time signal signal to plant plant contro controll system systems, s, but that that signal signal is availa available ble to any suitable suitable receiver receiver without charge. charge. Though this alternativ alternativee appear appearss to have have many many attrac attractiv tivee advant advantage ages, s, the utilit utility y industry in general has yet to implement widespread use of private networks based on satellite technology.
10-4. Communicatio Communication n System Selection Selection a. System Systemss extern external al to the plant plant .
In most most case cases, s, the the choice of the communications media used for dispatching and and remo remote te plan plantt cont contro roll and and moni monito tori ring ng will will not not be a responsibi responsibility lity of the plant designer. designer. The power-wheeli power-wheeling ng entity entity for the plant’ plant’ss power power produc productio tion n will will use system systemss and equipment equipment compatibl compatiblee with the utility’s utility’s “backbone” “backbone” comm commun unic icat atio ions ns netw networ ork. k. It is the the plan plantt desi design gner er’s ’s responsibility to ensure that adequate provisions are made for the communica communication tion system’s system’s terminal terminal equipment equipment and
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to ensure that plans and specifications prepared for powerhouse house equipm equipment ent and system systemss addres addresss specia speciall requir requireements for voice and data transmission as dictated by the extern external al commun communica icatio tion n system system.. Coordi Coordinat nation ion with with the system owner will be required to ensure compatibility. b. Design Design consid considera eration tionss.
Othe Otherr desig design n consi conside derrations ations include include interface interface requirements requirements for data circuits, circuits, as imposed by the communication utility due to FCC regulations, tions, and ground ground potential potential rise protectio protection n requiremen requirements ts for plant terminals of the metallic circuits used for voice, data data,, and and cont contro rol. l. In case casess wher wheree the the proj projec ectt scop scopee includ includes es develo developme pment nt of a commun communica icatio tions ns networ network, k, a comprehensive study should be made of alternatives available able includ including ing system system life-c life-cycl yclee costs costs to determ determine ine the most technically appropriate and cost-effective scheme to achieve achieve successful successful communica communications tions system system integratio integration. n. EPRI EL-5036, Volume 13, provides guidance on criteria to evaluate if the project scope includes development of a communications network. c. Internal Internal plant communication communicationss. Intern Internal al data data circircuits cuits (LANs) (LANs) will will be includ included ed with with the data data acquis acquisiti ition on and contro controll equipm equipment ent that that uses uses them, them, but the design designer er should should consider consider that fiber-opt fiber-optic ic technology technology will probably probably be used. Also, for large large plants plants to be staffed with adminis adminis-trativ trativee and mainte maintenan nance ce person personnel nel,, a networ network k of micromicrocomput computers ers may be added added after after the plant is in operat operation ion.. The plant plant design designer er should should provid providee facili facilitie tiess for routin routing g networ network k data data highwa highways ys betwee between n office offices, s, mainte maintenan nance ce shops, and the control room.
EM 1110-2-3006 30 Jun 94
Chapter 11 Direct-Current Direct-Current System
11-1. 11-1. Genera Generall A direct direct-cu -curre rrent nt system system is used used for the basic basic contro controls, ls, relayi relaying, ng, SCADA SCADA equipm equipment ent,, invert inverter, er, commun communica icatio tion n equipment equipment,, generator generator exciter exciter field field flashing, flashing, alarm function tions, s, and and emer emerge genc ncy y ligh lights ts.. The The syst system em cons consis ists ts of a storage storage battery battery with its associate associated d eliminat eliminator-ty or-type pe chargchargers, providing the stored energy system required to ensure adequa adequate te and uninte uninterru rrupti ptible ble power power for critic critical al power power plant equipmen equipment. t. The battery battery and battery circuits circuits should be properly designed, safeguarded and maintained, and the emergency emergency requirements requirements should be carefully carefully estimated estimated to ensure ensure adequate adequate battery battery performan performance ce during during emergenci emergencies. es. IEEE IEEE 946 and EPRI EPRI EL-503 EL-5036, 6, Volume Volume 9, provid providee guidguidance ance about about factor factorss to consid consider er and evalua evaluate te in planni planning ng and designing designing direct direct current systems. systems. IEEE 450 provides provides guideline guideliness and procedures procedures for testing the capacity capacity of the battery system.
11-2. Batteries Batteries a. Type Type. The The batt batter ery y or batte batteri ries es shoul should d be of the the lead-acid type in vented cells or a sealed cell. b. Batter Batteryy room room and mounting mounting. A separ separat atee room room or an area area enclos enclosed ed with with a chain chain link link fence fence with with lockab lockable le doors doors provid provides es adequa adequate te protec protectio tion n agains againstt accide accidenta ntall contact contact or malicious malicious tampering. tampering. The room or area should be ventilated in such a manner that exhaust air from the room does not enter any other room in the plant. If necessary, heat should be provided to obtain full rated performance mance out of the cells. cells. The cells cells should should be mounted mounted in rows on racks permitting viewing the edges of plates and the bottom bottom of the cells cells from one side of the battery battery.. The tops of all cells should preferably be of the same height abov abovee the the floo floor. r. The The heig height ht shou should ld be conv conven enie ient nt for for adding adding water water to the cells. cells. Tiered Tiered arrange arrangemen ments ts of cells cells should should be avoided. avoided. Aisles Aisles should be provided provided permitting permitting removal of a cell from its row onto a truck without reaching ing over over any othe otherr cell cells. s. The The ligh lighti ting ng fixtur fixtures es in the the room room should should be of the vapor-pr vapor-proof oof type, with the local contro controll switch switch mounte mounted d outsid outsidee by the entran entrance ce to the room. room. Batter Battery y chargi charging ng equipm equipment ent and contro controls ls should should not not be locate located d in the batt batter ery y room room.. Ther Thermo most stat atss for for heater control should be of the sealed type, and no contactors tors or other other arc-pr arc-produ oducin cing g device devicess should should be locate located d in the battery battery room. A fountain fountain eyewash-safet eyewash-safety y shower and drain should be provided in the battery room.
c. Numb Number er and and size sizess.
The The numbe numberr and size sizess of batteries depend upon the physical sizes of the initial and ultimate stages of plant construction and the loads to be carr carrie ied d by the the batt batter ery y syst system em.. A 58/6 58/600-ce cell ll batt batter ery y (129 (129-V -V)) is adeq adequa uate te for for a plan plantt with with four four to six six main main units. units. Where Where a large large plant has a consid considera erable ble amount amount of emerge emergency ncy lighti lighting, ng, long long circui circuits, ts, and a high high number number of solenoid loads, a 116/120-cell battery may be warranted. d. OneOne- or two-batte two-battery ry systems systems. If the ultim ultimate ate plant plant
will will have have a larg largee numb number er of gene genera rati ting ng unit units, s, stud studie iess should be made to determine whether one control battery for the ultimate plant will be more desirable and economically cally justifiab justifiable le instead instead of two or more smaller batteries batteries instal installed led as the plant grows. grows. Select Selection ion of a oneone- or twotwobattery system will depend not only on comparative costs of differ different ent batter battery y sizes sizes and combin combinati ations ons,, includ including ing circuits and charging facilities, but consideration of maximum dependabil dependability, ity, performan performance, ce, and flexibili flexibility ty during during periods of plant expansion. e. DC loa load d . The recommen recommended ded procedure procedure for deterdetermining the proper battery rating is outlined in IEEE 485. The standard classifies the total DC system load into the following categories:
(1) Moment Momentary ary loads. loads. Moment Momentary ary loads loads consist consist of switch switchgea gearr operat operation ions, s, genera generator tor excite exciterr field field flashi flashing, ng, voltage voltage regulators, regulators, and similar devices. devices. Momentary Momentary loads are assumed to be applied for 1 min or less. (2) (2) Non Nonco cont ntin inuo uous us load loads. s. Nonc Noncon onti tinu nuou ouss load loadss consis consistt of emerge emergency ncy pump pump motors motors,, fire fire protec protectio tion n syssystems, tems, and similar similar systems. systems. Noncontinu Noncontinuous ous loads are those only energized for a portion of the duty cycle. (3) Contin Continuou uouss loads. loads. Contin Continuou uouss loads consist consist of indica indicatin ting g lamps, lamps, invert inverters ers,, contac contactor tor coils, coils, and other other contin continuou uously sly energize energized d device devices. s. Contin Continuou uouss loads loads are assumed to be applied throughout the duty cycle. f. Emergency loads.
In cas cases where where emer emerge genc ncy y ligh lighti ting ng is exce excess ssiv ive, e, the the emer emerge genc ncy y load load shou should ld be broken down into two separate loads: (1) (1) Thirt Thirtyy-mi minu nute te emer emerge genc ncy y load load.. The The 30-m 30-min in emergency load consists of emergency lights that can be conveniently disconnected from the DC system when the location of the trouble has been determined. (2) (2) Thre Threee-ho hour ur emer emerge genc ncy y load load.. The The 3-hr 3-hr emer emer-gency load consists of the emergency lights required after the trouble area has been determined.
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EM 1110-2-3006 30 Jun 94 g. Batter Batteryy capacity capacity. Using Using the above above load class classes es and
durations durations and battery battery data obtained obtained from manufacturer’s manufacturer’s literatur literature, e, a station station battery battery duty cycle is determine determined d (see IEEE IEEE 485). 485). The battery battery capaci capacity ty required required is determ determine ined d as the sum of the requirements for each class and duration of load comprising the duty cycle. h. Batter Batteryy and access accessory ory purcha purchase se.
The The batt batter erie ies, s, with their accessori accessories, es, indicating indicating cell connector connectors, s, hydrohydrometers, cell number, etc., are normally purchased through the GSA Schedule. Schedule. Standard Standard battery battery racks for the battery battery installation may also be obtained through GSA Schedules.
rech rechar argi ging ng the the stat statio ion n batt batter ery y at a norm normal al rate. rate. The The chargers should be of the “battery eliminator” type (additional tional filtering filtering)) allowing allowing them to carry carry station station DC loads while the battery battery is disconnected disconnected for service. service. The batterybatterycharger systems should be located near the battery room, usually in a special room with the battery switchboard and the the inve invert rter er sets sets.. Stan Standa dard rd comm commer erci cial al feat featur ures es and and options options available available with station station and communica communication tion battery chargers are outlined in NEMA PE5 and PE7.
11-4. Inverter Inverter Sets
Standa Standard rd rack rack perform performanc ancee criter criteria ia should should be evalua evaluated ted to ensure ensure compli complianc ancee with with plant plant requir requireme ements nts.. Seismi Seismicc consid considera eratio tions ns and other factors may dictate the need for special racks and special anchor anchoring ing needs. needs. The racks, racks, anchor anchors, s, and instal installat lation ion practices, practices, including including seismic seismic considerat considerations, ions, are discussed discussed in IEEE 484 and IEEE 344. Electr Electrica icall safety safety consid considererations for battery installations are covered in Article 480 of the National Electrical Code (NFPA 70).
One inverter set should be provided in all plants where it is necess necessary ary to mainta maintain in a contin continuou uouss source source of 120-V 120-V AC. A separate separate supply bus for selected selected 120-V 120-V AC singlephase phase feeder feeder circui circuits ts should should be provid provided ed for SCADA, SCADA, recording instrument motors, selsyn circuits, and communication nication equipment. equipment. A transfer switch switch should be provided to automatically transfer the load from the inverter output to the station service AC system feeder in case of inverter failure. failure. Standard Standard commercial commercial features features and options options available with inverters used in uninterruptible power supplies are outlined in NEMA PE1.
11-3. Battery-Cha Battery-Charging rging Equipment Equipment
11-5. Battery Battery Switchboar Switchboard d
Static Static charger charger sets are preferred preferred for battery-ch battery-chargin arging g service. vice. Two sets sets should should be provide provided d so one will will always always be availa available ble.. The charger charger capaci capacity ty should should be suffic sufficien ientt for supplying the continuous DC load normally carried while
Batt Batter ery y brea breake ker, r, DC feed feeder er brea breake kers rs,, amme ammete ters rs,, and and ground ground and underv undervolt oltage age relays relays should should be groupe grouped d and mounted mounted in a battery battery switchboar switchboard. d.
i. Safety considerat considerations ions.
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EM 1110-2-3006 30 Jun 94
Chapter 12 Lighting and Receptacle Systems
12-1. 12-1. Des Design ign a. Genera Generall.
For For the the purp purpos oses es of desi design gn and and plan plan prepar preparati ation, on, the lighti lighting ng system system is define defined d as beginn beginning ing with with the lighti lighting ng transf transform ormers ers and extend extending ing to the fixfixture tures. s. This This faci facili lita tate tess desi design gn coor coordi dina nati tion on of vari variou ouss featur features es of the lightin lighting g system system.. For purposes purposes of discus discus-sion, it also covers 480-V and 120-V convenience outlets and correspondi corresponding ng circuits. circuits. After the design design is complete, complete, the system may be broken down into separate categories as determined by how the equipment will be obtained and instal installed led in the constru constructi ction on stage. stage. One method method of hanhandling the division division of work is outlined outlined below. below. The lighting lighting systems, systems, including including fixtures and receptacl receptacles, es, are normally normally furnished and installed by the powerhouse contractor. b. Condui Conduitt and cable schedule schedule.
Supp Supply ly cabl cables es and and condui conduitt to transf transform ormers ers and lighti lighting ng panels panels should should be listed listed in the conduit conduit and cable cable schedu schedule. le. Branch Branch circuit circuitss are normally not included on the schedule. c. Pane Panels ls. Lighting Lighting panels panels should be designed designed for the job, using air circuit breakers to protect the branch circuits, and should be purchased and installed by the general contractor. d. Distrib Distributio ution n center center . In designi designing ng the lighti lighting ng disdis-
tribution tribution system, several several schemes schemes should should be considered considered,, and a scheme adopted which gives the lowest overall cost without without sacrifici sacrificing ng simplici simplicity ty of design design or efficienc efficiency y of operation operation.. Two general general schemes schemes are: (1) Small Small plant. plant. A centra centrally lly locate located d lighting lighting transtransformer supplying the entire plant, which may be either: (a) A 480-120/24 480-120/240-V, 0-V, single-pha single-phase se transforme transformerr with 120/240-V feeders and branch circuits. (b) A 480-12 480-120/2 0/20808-V, V, 3-phas 3-phase, e, 4-wire 4-wire transf transform ormer er with 120/208-V feeders and branch circuits. (c) A 480-48 480-480Y/ 0Y/277 277-V, -V, 3-phas 3-phase, e, 4-wire 4-wire transf transform ormer er with 480Y/277-V feeders and branch circuits. (2) Large Large plant. plant. Transf Transform ormers ers locate located d near near the load load center centerss and fed by indivi individua duall supply supply feeder feederss from from the statio station n servic servicee switch switchgea gearr to supply supply lighti lighting ng for a local local area, each transformer being either:
(a) (a) A 480480-12 120/ 0/24 2400-V, V, sing single le-p -pha hase se tran transf sfor orme mer, r, feeding panels with 120/240-V branch circuits. (b) A 480-12 480-120/2 0/20808-V, V, 3-phas 3-phase, e, 4-wire 4-wire transf transform ormer, er, feeding panels with 120/208-V branch circuits. (c) A 480-480Y/2 480-480Y/277-V, 77-V, 3-phase, 3-phase, 4-wire 4-wire transforme transformer, r, feeding panels with 480Y/277-V branch circuits.
12-2. Illumination Illumination Requireme Requirements nts a. Intensi Intensity ty level level. The The ligh lighti ting ng syste system m shou should ld be designed to give the maintained-in-service lighting intensities recommended by the IES Handbook (Kaufman 1984). A maintenance factor of 0.75 is considered appropriate for a well-maintained project. b. Emerge Emergency ncy lightin lighting g.
Emerge Emergency ncy light lighting ing shoul should d be design designed ed to light light import important ant workin working g areas areas within within the powerhouse and should be adequate to provide safe passage sage betw betwee een n such such area areass with with a mini minimu mum m load load on the the statio station n batter battery. y. NFPA 101 provides provides guidanc guidancee on areas requiring requiring emergency emergency lighting lighting for personnel personnel safety. safety. Selfcontained, contained, battery-op battery-operat erated, ed, emergency emergency lighting lighting systems systems should should be considere considered d to lower capacity capacity requireme requirements nts on the station station battery. Self-conta Self-contained, ined, battery-o battery-operat perated ed systems tems should should be employ employed ed in areas areas with with minima minimall occuoccupancy pancy or person personnel nel access access follow following ing an event event initia initiatin ting g use of the emergency emergency lighting lighting system. system. Emergency Emergency lightlighting for contro controll rooms, rooms, unit unit contro controll switch switchboa board rd areas, areas, station service switchgear areas, the emergency generator area, area, and interc interconn onnect ecting ing passag passagewa eways ys betwee between n these these areas should be powered by the station battery. c. Exterio Exteriorr lighting lighting.
Exte Exteri rior or light lightin ing g shou should ld be provided provided for the switchyard switchyard,, parking parking areas, areas, passageways passageways near near the the powe powerh rhou ouse se,, the the draf draftt tube tube deck deck,, and and for for the the upstre upstream am deck if there there is one. one. FloodFlood-lig lighti hting ng of the outside powerhouse walls should be included in the original design design,, with with provis provision ionss made made for extens extension ion of lighti lighting ng circuits circuits if the floodlights floodlights are not initially initially installed. installed. Exterior rior door doorwa ways ys shou should ld be ligh lighte ted d eith either er by flus flush h soff soffit it lights lights or by bracket bracket lights. lights. If bracket bracket lights are used, used, they should be selected to enhance the architectural appearance of the doorways. d. Specifi Specificc conditi conditions ons. For For genera generall areas, areas, the zonal zonal cavity method of illumination design (see IES Handbook) is considered considered satisfacto satisfactory. ry. For special special conditions conditions such as illumi illuminat nation ion (Kaufm (Kaufman an 1984) 1984) of the vertic vertical al surfac surfaces es of swit switch chbo boar ards ds,, a care carefu full chec check k by the the poin pointt-by by-p -poi oint nt metho ethod d may may be neede eeded. d. Care Care sho should uld be taken aken to
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EM 1110-2-3006 30 Jun 94 minimi minimize ze reflec reflected ted glare glare from from the faces faces of switch switchboa board rd instrumen instruments. ts. To facilitate facilitate design review, review, the manufacturmanufacturer’s candlepowe candlepowerr distributi distribution on curves curves should should accompany accompany the design design drawin drawings. gs. If fixture fixturess of unusua unusuall design design are being specified, their use must be justified, with complete details details of the fixtures fixtures submitted submitted with the lighting lighting design data. e. Evalua Evaluation tion. Eval Evalua uati tion on and and choi choice ce of light lightin ing g system systemss should should consid consider er both both energy energy and mainte maintenan nance ce costs as well as initial cost of the fixtures.
12-3. Efficiency Efficiency a. Genera Generall. Ener Energy gy cons conser erva vati tion on is an impo import rtan antt concern concern when designing designing lighting lighting systems. systems. In the powerhouse, use of high efficiency lighting has the potential for saving saving significant significant amounts amounts of energy. energy. An efficient efficient lighting system is one in which the required amount of light reaches the area to be illuminated at the proper level and color, color, while while using using the minimu minimum m amount amount of energy. energy. The well-designed lighting system should make maximum use of availa available ble natura naturall light light and consid consider er the direct direction ion of light light and the desired desired dispers dispersion ion or focus. focus. Encour Encouragi aging ng effici efficient ent use requir requires es provis provision ion of conven convenien ientt contro controll points, points, use of proximity proximity detectors detectors in unoccupied unoccupied interior interior spaces spaces,, and consid considera eratio tion n of two-le two-level vel light lighting ing in lowlowoccupancy machinery areas.
(b) (b) HID HID meta metall hali halide de lamp lampss are are a good good sour source ce of “white “white”” light, light, coveri covering ng about about 70 percen percentt of the visibl visiblee spec spectr trum um.. They They have have good good life life and and are are very very effi effici cien ent. t. Their Their disadv disadvant antage agess are relati relativel vely y long long start start and restar restartt times. (c) HID high pressure pressure sodium sodium lamps lamps are very efficient, cient, but are a poor poor source source of “white “white”” light light,, coveri covering ng only only about about 21 percen percentt of the availabl availablee spectr spectrum. um. They They need about 3 or 4 min of start time, and about 1 min of restart time. (4) Low-pr Low-press essure ure sodium sodium (LPS) (LPS).. LPS lamps lamps are the most most effici efficient ent lamps lamps availa available ble,, but produc producee almost almost no “whi “white te”” ligh light, t, so thei theirr use use is extr extrem emel ely y limi limite ted. d. They They have have long long lives, lives, short short start start times, times, and very very short short restar restartt times. c. Evalua Evaluation tion. When When design designing ing the lightin lighting g system system,,
all all of the the abov abovee sour source cess shou should ld be cons consid ider ered ed and and the the most efficient efficient combinatio combination n of sources sources used, appropriate appropriate with with achiev achieving ing design design lighti lighting ng levels levels and good good lighti lighting ng qual qualit ity. y. Eval Evalua uati tion on and and choi choice ce shou should ld cons consid ider er both both energy energy and mainte maintenan nance ce costs, costs, as well well as initia initiall cost cost of the the fixt fixtur ures es.. EPRI EPRI TR-10 TR-1017 1710 10 prov provid ides es guid guidan ance ce on achiev achieving ing design design lighti lighting ng levels levels in an energy energy-ef -effic ficien ient, t, cost-effective manner.
12-4. Conductor Conductor Types Types and Sizes Sizes b. Ligh Lightin ting g sour source ce type typess.
Effi Effici cien entt ligh lightt sour source cess should should be consid considere ered. d. There There are four four common common lighti lighting ng source categories, as follows: (1) (1) Inca Incand ndes esce cent nt.. In gene genera ral, l, inca incand ndes esce cent nt lamp lampss provid providee the “whitest “whitest”” light, light, but at a higher higher energy energy cost cost and relativ relatively ely short short life. life. Incand Incandesc escent ent lamps lamps are used where fluorescent fixtures are not practical for reasons of vapor, limited space, high lighting levels, or the need for superior color rendition. (2) Fluorescen Fluorescent. t. Triphospho Triphosphorr fluorescen fluorescentt lamps are are a good source of “white” light and are relatively long-lived, with energy energy efficienc efficiencies ies better better than incandesc incandescent ent lamps. lamps. Most rooms and shops should be illuminated with energyefficient efficient,, fluoresce fluorescent nt fixtures, fixtures, using T-8 high-effi high-efficienc ciency y lamps and electronic ballasts. (3) High-inten High-intensity sity discharge discharge (HID). (a) (a) HID HID merc mercur ury y lamp lampss are are fair fairly ly effi effici cien ent, t, have have relatively long lives, but are not a good source of “white” ligh light, t, cove coveri ring ng only only abou aboutt 50 perc percen entt of the the visi visibl blee spectrum.
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The The volt voltag agee drop drop in pane panell supp supply ly circ circui uits ts shou should ld be limite limited d to 1 perc percent ent if possib possible, le, and the drop in branch branch circui circuits ts should should be limited limited to 2 percen percent. t. If it is not possipossible to limit the voltage drop to these figures, a limit of 3 percen percentt for the total total voltag voltagee drop drop should should be observ observed. ed. In arriving at the voltage at the load, the impedance drop throug through h the transf transform ormer er should should be consid considere ered, d, althou although gh this drop need not be considered in feeder or branch circuit cuit desi design gn.. Bran Branch ch circ circui uitt and and pane panell feed feeder er desi design gn should be based on the considerations outlined in Chapter 15. 15. Mini Minimu mum m cond condui uitt size size shoul should d be 3/4 in. and the the minimum conductor size should be No. 12 AWG.
12-5. Emergency Emergency Light Light Control Control A system system employing employing selected fixtures normally supplied from the AC source through an automatic transfer switch transferring the fixtures to the DC system on AC voltage failur failuree should should be provid provided. ed. Fixtur Fixtures es sourced sourced from the statio station n batter battery y should should be minimi minimized zed to reduce reduce batter battery y drain (see paragraph paragraph 12-2b). Retu Return rn to the the AC sour source ce should be automatic when the AC source is restored.
EM 1110-2-3006 30 Jun 94 12-6. Control Control Room Lighting Lighting a. Genera Generall. Many Many differen differentt schemes schemes have been been used in attempti attempting ng to develop develop “perfect” “perfect” control room lighting. lighting. This emphasis is due to the difficult and continuous visual tasks that that are performed performed in the control control room. Task ambiambient ent ligh lighti ting ng prov provid ides es the the most most effe effect ctiv ivee appr approa oach ch to achieving achieving desired desired results. results. IES-RP-24 IES-RP-24 provides provides guidance guidance on topics topics such as quality quality of illumination illumination,, luminance luminance levels, els, and and the the visu visual al comf comfor ortt of room room occu occupa pant nts, s, whic which h must be evaluated evaluated in developing developing a control control room lighting lighting design. b. VDTs VDTs and instrumen instrumentt faces. Plant Plant contro controll systems systems
use visual display terminals (VDTs) which tend to “wash out” in high ambient lighting, and the VDT face reflects ligh lightt from from sour source cess behi behind nd the the oper operat ator or that that make make the the screen screen image unreadable. unreadable. Switchboar Switchboard d instrument instrument faces also reflect light, and such reflections obscure the instrument ment dial. dial. Light Light fixture fixturess or window window areas areas should should not be reflected by the instrument glass and VDT screen. c. Switch Switchboa board rd lighting lighting.
Swit Switch chbo boar ards ds shou should ld be lighte lighted d so that that the instru instrumen mentt major major scale scale markin markings gs and pointers can be readily seen from the control console even though the actual numbers opposite these markings cannot be read. read. Suffic Sufficien ientt vertic vertical al illumi illuminat nation ion on the fronts fronts of the boards boards is only only part part of the answer answer.. Illumi Illuminat nation ion must be provided in a manner that does not produce glare from the instru instrumen mentt glass, glass, or object objection ionabl ablee shadow shadowss on the instru instrumen mentt face face from from the instru instrumen mentt rims rims and contro controll swit switch ches es.. It is also also import importan antt that that no ligh lightt sour source ce be visible in the line of the operator’s vision when viewing the boards. d. Lightin Lighting g criter criteria ia.
Extr Extrem emee cont contra rast stss in ligh lighte ted d areas, areas, such as a bright bright ceiling ceiling or wall wall visibl visiblee above above the switchboard, must be avoided, as they produce eye strain. The modern practice of using light-colored switchboards, and the latest latest design design of indicatin indicating g instrument instrument dials have both both help helped ed to impr improv ovee cont contro roll room room ligh lighti ting ng.. Good Good contro controll room room lighti lighting ng will will be obtain obtained ed if the follow following ing criteria are observed: (1) Adequa Adequate te vertic vertical al illum illumina inatio tion n on vertic vertical al board board surfaces. (2) Bright Brightnes nesss contra contrasts sts prefer preferabl ably y within within a ratio ratio of 1 to 3. (No light light sources sources in line of vision). vision). (3) (3) No spec specul ular ar refl reflec ecti tion on from from inst instru rume ment nt,, VDT screen, or other surfaces.
(4) No objectionabl objectionablee shadows on working surfaces. surfaces. e. Heat Heat . The amount amount of heat from from the lamps lamps (of any type) in the control room must be given special consideration in designing the air-conditioning layout for the control room and adjacent areas.
12-7. Hazardous Hazardous Area Lighting Lighting Battery room and oil room fixtures should be vapor- and explosion-proof type, and local control switches should be mounted mounted outside outside the door. Lighting Lighting switches switches of the standard dard vari variet ety y may may be used used by plac placin ing g them them outs outsid idee the the room door. door. Convenienc Conveniencee receptacles receptacles in the rooms should should be avoided, or where necessary, be of the explosion-proof type.
12-8. Receptacles Receptacles The The type typess and and rati rating ngss of rece recept ptac acle less for for conv conven enie ienc ncee outl outlet etss shou should ld be clea clearl rly y indi indica cate ted d on the the fixt fixtur uree and and device device schedule schedule sheet in the drawings drawings,, or in the bill of materi materials als.. Standa Standardi rdizat zation ion of recept receptacl acles es allows allows use of portable portable equipment equipment throughout throughout the project. project. The following following recept receptacl acles es are sugges suggested ted as the approp appropria riate te qualit quality y and type: a. 480-V 480-V rece recept ptac acle less. 3-wire, 4-pole, 30 A, grounded through extra pole and shell of plug type receptacl tacles es are are reco recomm mmen ende ded. d. The The rece recept ptac acle less and and plug plugss should meet the requirements of ANSI/UL 498 and should be weather weather resistant resistant for use in wet and dry dry locations. locations. For weldin welding g machin machines es and other other portab portable le 480-V 480-V equipm equipment ent,, use two-gang-type cast boxes to ensure adequate room for No. 6 AWG feeders, except for the placement of 480-V rece recept ptac acle less at the the end end of cond condui uitt runs runs,, whic which h may may be single-gang receptacles. b. 120-/20 120-/208-V 8-V recept receptacl acles es.
4-wi 4-wire re,, 5-po 5-polle, 30 A, grounded type receptacles, plugs, and fixtures meeting the requirements of ANSI/UL 498 and 514 are recommended. Typically, these fixtures are used to service supplemental lighting in work areas during overhauls. c. 120-V 120-V recept receptacl acles es.
The The choic choicee betwe between en usin using g a twist-lock twist-lock receptacl receptaclee or using a parallelparallel-blade blade receptacl receptaclee has never been been standardized standardized nationwi nationwide. de. There is a trend to employ employ parallelparallel-blade blade receptacles receptacles on new constructi construction on projec projects. ts. Parall Parallelel-bla blade de recept receptacl acles es are recomm recommend ended ed unless unless there there is a strong strong local local prefer preferenc encee for twisttwist-loc lock k rece recept ptac acle less base based d on exis existi ting ng loca locall stan standa dard rdiz izat atio ion. n. Ground Ground fault fault protec protectio tion n should should be provid provided ed for 120-V 120-V
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EM 1110-2-3006 30 Jun 94 outlet outletss in all wet locatio locations ns or outdoors outdoors.. Use appropri appropriate ate ground fault interrupter circuit breakers in these locations. (1) TwistTwist-loc lock k recept receptacl acles. es. For project projectss using using twisttwistlock receptacles, 3-pole, 15-A, 125-V, grounding, duplex, twisttwist-loc lock, k, NEMA NEMA L5-15R L5-15R config configura uratio tion n for use with with comp compat atib ible le twis twistt-lo lock ck caps caps are are reco recomm mmen ende ded d for for dry dry locations locations within within all powerhouse areas. areas. For wet locations locations or outdoors, a similar single-gang receptacle in a cast box with twist-lock twist-lock caps caps or plugs is recommend recommended. ed. For lunch rooms, rooms, office office areas, areas, lounges lounges and restrooms, restrooms, duplex duplex combinati bination, on, twisttwist-loc lock, k, straig straightht-bla blade de recept receptacl acles, es, NEMA NEMA L5-15R configuration, are recommended. (2) (2) Stra Straig ight ht-b -bla lade de rece recept ptac acle les. s. For For proj projec ects ts usin using g straight-blade receptacles, 3-pole, 20-A, 120-277-V grounding, duplex, hospital grade, NEMA 5-20R configuration, are recommend recommended ed for dry locations. locations. For wet locations locations or outdoor use, single, hospital-grade receptacles in the same configurat configuration, ion, with weatherpr weatherproof oof single-re single-recepta ceptacle cle cover plates are recommended.
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EM 1110-2-3006 30 Jun 94
Chapter 13 Grounding Systems
e. Durati Duration on of the fault fault and body contact contact for a suffisuffi-
cient time to cause harm.
13-3. Field Exploration Exploration 13-1. 13-1. Genera Generall a. Purpos Purposee. A safe groundi grounding ng design design has two objecobjectives: tives: to carry electri electricc curren currents ts into earth earth under normal normal and fault fault condit condition ionss withou withoutt exceed exceeding ing operat operating ing and equipm equipment ent limits limits or advers adversely ely affect affecting ing contin continuit uity y of serv servic icee and and to assu assure re that that a pers person on in the the vici vicini nity ty of grounded facilities is not exposed to the danger of electric shock. b. Refere Reference nce.
IEEE 142 142, known as “The Green Book,” Book,” covers covers practi practical cal aspect aspectss of ground grounding ing in more more detail, detail, such as equipment equipment grounding, grounding, indoor indoor installat installations, ions, cable sheath sheath grounding, grounding, etc. This standard standard provides provides guidance ance in addres addressin sing g specif specific ic ground grounding ing concerns concerns.. AddiAdditional tional guidance guidance for powerhouse powerhouse-spe -specific cific grounding grounding issues issues is provided in EPRI EL-5036, Volume 5.
13-2. Safety Safety Ha Hazards zards The existence of a low station ground resistance is not, in itself, itself, a guarantee of safety. safety. During During fault conditions, conditions, the flow flow of curren currentt to earth earth will will produc producee potent potential ial gradie gradients nts that may be of sufficient magnitude to endanger a person in the area. area. Also, Also, danger dangerous ous potenti potential al differen differences ces may develo develop p betwee between n ground grounded ed equipm equipment ent or struct structure uress and near nearby by eart earth. h. IEEE IEEE 80 prov provid ides es deta detail iled ed cove covera rage ge of design issues relating to effective ground system design. It provides a detailed discussion of permissible body current limi limits ts and and shou should ld be revi review ewed ed prio priorr to deve develo lopi ping ng a grounding grounding design. design. It is essential essential that the grid design design limit step and touch voltages to levels below the tolerable levels identif identified ied in the standar standard. d. The conditio conditions ns that that make make electric shock accidents possible are summarized in Chapter 2 of the guide and include: a. High High fault fault current current to ground ground in relation relation to the area area
of ground system and its resistance to remote earth. b. Soil resistivit resistivity y and distributio distribution n of ground currents currents
such that high potential gradients may occur at the earth surface. c. Presence Presence of an individual individual such that the individual individual’s ’s body is bridging two points of high potential difference. d . Absenc Absencee of suffic sufficien ientt contac contactt resist resistanc ancee to limit limit
current through the body to a safe value.
After After prelim prelimina inary ry layout layoutss of the dam, dam, powerh powerhous ouse, e, and switchyard have been made, desirable locations for two or more ground ground mats can be determined. determined. Grounding Grounding condiconditions tions in these these areas areas should should be invest investiga igated ted,, and the soil soil resistanc resistancee measured. measured. IEEE 81 outlines methods methods for field tests tests and formulas for computing computing ground electrode resistances. tances. Sufficient Sufficient prospect prospecting ing should be done to develop a suit suitab able le loca locati tion on for for the the grou ground nd mat mat coup couple led d with with a determina determination tion of average average soil resistivity resistivity at the proposed proposed loca locati tion on.. IEEE IEEE 81 desc descri ribe bess and and endo endors rses es use use of “the “the Wenn Wenner er four four-p -pin in meth method od”” as bein being g the the most most accu accura rate te procedure procedure for making the soil resistivity resistivity determina determination. tion. It also provides information on other recognized field measurement techniques.
13-4. 13-4. Ground Ground Mats Mats a. General General requirements requirements.
The The measur measured ed soil soil resis resis-tivity tivity obtain obtained ed by field field explor explorati ation on is used used to determ determine ine the the amou amount nt of grou ground nd grid grid nece necess ssar ary y to deve develo lop p the the desire desired d ground ground mat resist resistanc ance. e. The resistan resistance ce to ground ground of all power plant, dam, and switchyard mats when connect nected ed in para parall llel el shou should ld not not exce exceed ed,, if prac practi tica cabl ble, e, 0.5 0.5 ohm ohm for for larg largee inst instal alla lati tion ons. s. For For smal smalll (150 (1500 0 kW ) plan plants ts,, a resi resist stan ance ce of 1 ohm ohm is gene genera rall lly y acce accept ptab able le.. Practi Practical cal electr electrode ode drive drive depth depth should should be determ determine ined d in the field. field. A depth reaching reaching permanent permanent moisture moisture is desirdesirable. able. The effecti effective ve resistan resistance ce of, and the step and touch pote potent ntia ials ls for, for, an enti entire re grou ground nd mat mat with with a numb number er of electr electrode odess in parall parallel el can be determ determine ined d from from IEEE IEEE 80. The diamet diameter er of the electr electrode ode is determ determine ined d by drivin driving g requir requireme ements nts.. Copper Copper-we -weld ld ground ground rods rods of 3/4 in. diam diam are are usua usuall lly y sati satisf sfac acto tory ry wher wheree driv drivin ing g dept depths hs do not not exceed exceed 10 ft. For greate greaterr depths depths or difficul difficultt soil soil condiconditions, tions, 1-in.-di 1-in.-diam am rods rods are preferre preferred. d. Galvan Galvanize ized d pipe pipe is not suitable for permanent installations. b. Locatio Location n. The The dept depth h and and cond condit itio ion n of the the soil soil upstre upstream am from from the dam on the flood plain is freque frequentl ntly y favo favora rabl blee for for plac placem emen entt of one one or two two grou ground nd mats mats.. These can be used for the grounding of the equipment in the dam and leads extended to the grounding network in the powerh powerhous ouse. e. At least least one ground ground mat should should be proprovided under or near the switchyard. c. Lead Leadss. Leads Leads from groun ground d mats should should be suffisuffi-
ciently large to be mechanically durable, and those which
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EM 1110-2-3006 30 Jun 94 may carry large fault currents should be designed to minimize mize IR drop. Two leads, leads, preferab preferably ly at opposi opposite te ends of the mat, should be run to the structure or yard, and the entire layout designed to function correctly with one lead disc discon onne nect cted ed.. The The desi design gn and and loca locati tion on of conn connec ecti ting ng leads should account account for constructi construction on problems problems involved in preserving the continuity of the conductor during earth movi oving, ng, concr oncret etee plac placeement ment,, and and for form remov emoval al operations.
(2) (2) Copp Copper er bar bar rath rather er than than cabl cablee is pref prefer erre red d for for expo expose sed d runs runs of bus. bus. Gene Genera rato torr lead leadss of the the meta metallenclosed type will be equipped by the manufacturer with a ground grounding ing bar interc interconn onnect ecting ing all bus suppor supports. ts. ProProperl perly y conn connec ecte ted, d, this this form formss a link link in the the powe powerh rhou ouse se ground bus. (3) In selecting selecting conductor conductor sizes for the main main grounding ing netw networ ork, k, thre threee cons consid ider erat atio ions ns shou should ld be born bornee in mind:
d. Types Types of groun ground d mats. Topogr Topograph aphy y of the site, soil soil
condit condition ions, s, and depth depth of soil soil above above bedroc bedrock k are factor factorss influencing not only the location, but type of ground mat used. used. Some Some common common types types (in additio addition n to forebay forebay location) are: (1) Ground Ground rods rods driven driven to perman permanent ent moisture moisture and interc interconn onnect ected ed by a grid grid system system of bare, bare, soft soft anneal annealed ed copper copper conductors. conductors. This type of mat is preferable. preferable. (2) (2) A grid grid of inte interc rcon onne nect cted ed cond conduc ucto tors rs laid laid in trenches dug to permanent moisture below the frost line. (3) (3) Grou Ground nd well wellss with with stee steell casi casing ngss used used as elec elec-trodes trodes,, or holes holes in rock rock with with insert inserted ed copper copper electr electrode odess and the hole backfille backfilled d with bentonite bentonite clays. The wells or holes should penetrate to permanent moisture. (4) Plate Plate electr electrode odess or grids grids laid laid in the powerhou powerhouse se tailrace, suitably covered or anchored to remain in place. e. Ground Ground resista resistance nce test . A test test of the over overal alll propro-
ject ground resistance should be made soon after construction. tion. Constructi Construction on contract specifica specifications tions should should contain provisions provisions for adding adding ground ground electrode electrodess if tests tests indicate indicate that that this this is nece necess ssar ary y to obta obtain in the the desi design gn resi resist stan ance ce.. Proper measurement of the resistance to ground of a large mat or group of mats requires placement of the test electrod trodes es at a cons consid ider erab able le dist distan ance ce (ref (refer er to IEEE IEEE 81). 81). Transmission line conductors or telephone wires are occasionally used for test circuits before the lines are put into service.
13-5. Powerhouse Powerhouse Grounding Grounding a. Main groundin grounding g network network .
(1) This network network should consist consist of at least two major runs runs of ground grounding ing conducto conductors rs in the powerh powerhous ouse. e. Major Major items items of equipm equipment ent such such as genera generator tors, s, turbin turbines, es, transtransformers, formers, and primary primary switchgear switchgear should should be connected connected to these grounding “buses” so there are two paths to ground from each item of equipment.
13-2
(a) The conduct conductors ors should should be large large enough so that that they will not be broken during construction. (b) (b) Curr Curren entt-ca carr rryi ying ng capa capaci city ty of the the cond conduc ucto tors rs should be sufficient to carry the maximum current for a fault fault to ground ground for a minim minimum um period period of 5 sec sec withou withoutt damage to the conductor (fusing) from overheating. (c) (c) The The tota totall resi resist stan ance ce of the the load loadss from from majo majorr items of equipment should be such that the voltage drop in the cable under fault conditions will not exceed 50 V. b. Equipm Equipment ent .
Miscel Miscellan laneou eouss electr electrica ically lly operate operated d equipm equipment ent in the powerh powerhous ousee should should be ground grounded ed with with taps taps from from the the main main grou ground nd netw networ ork. k. For For mech mechan anic ical al streng strength, th, these these conduc conductor torss should should be not less less than than No. 6 AWG. The resistance resistance of these these taps should should keep the voltvoltage drop in the leads to the ground mat to less than 50 V. They They shou should ld carr carry y the the curr curren entt from from a faul faultt to grou ground nd without damage to the conductor before the circuit protective device device trips. Provisions Provisions should should be made in the design design of the the powe powerh rhou ouse se grou ground ndin ing g syst system em for for bare bare copp copper er cabl cablee taps taps of suff suffic icie ient nt leng length th to allo allow w conn connec ecti tion on to equipm equipment ent instal installed led after after instal installat lation ion of the ground grounding ing system. system. Generally, Generally, the tap connection connection cable cable is coiled in a concrete blockout for easy accessibility later when attaching the tap to the housing of the equipment with pressure connec connector tors. s. Items Items of minor minor equipm equipment ent may be ground grounded ed by a bare bare wire wire run in the conduit conduit from the distrib distributi ution on center center to the equipme equipment. nt. The neutral neutralss and enclosu enclosures res of lighting and station service power transformers should be ground grounded. ed. Distri Distribut bution ion center center and lighting lighting panel encloenclosures as well as isolated conduit runs should be grounded. c. Conductor Conductor size selectio selection n. Ground Ground condu conducto ctorr sizes sizes shou shoulld be limit imited ed to Nos Nos. 6, 2, 2/0, 2/0, 250 250 kCM and and 500 500 kCM kCM,, or larg larger er,, to limi limitt orde orderi ring ng inve invent ntor orie iess and and acce access ss norm normal ally ly stoc stocke ked d cond conduc ucto torr size sizes. s. Subj Subjec ectt to short-circuit studies, usage, in general, is as follows:
(1) No. 6: Control Control cabinets, cabinets, special special outle outlets, ts, machinmachinery, lighting standards, power distribution equipment with
EM 1110-2-3006 30 Jun 94 main main feed feeder erss #2 or less less,, and and moto motorr fram frames es of 60 hp or less. (2) (2) No. No. 2: Swit Switch chbo boar ards ds,, gove govern rnor or cabi cabine nets ts,, larg largee tanks, power distribution equipment with primary or seconda ondary ry feed feeder erss 250 250 kCM kCM or less less,, and and moto motorr fram frames es between 60 and 125 hp. (3) No. 2/0: Roof steel, steel, crane crane rails, rails, generator generator neutra neutrall equipment, gate guides, power distribution equipment with primar primary y or second secondary ary feeder feederss larger larger than than 250 kCM, kCM, and motor frames larger than 125 hp. (4) 250 kCM: kCM: Turbin Turbinee stay-r stay-ring ings, s, turbine turbine pit liners liners,, gene genera rato torr hous housin ings gs and/ and/or or cove coverr plat plates es,, larg largee stat statio ion n service service transforme transformers, rs, transmissi transmission on tower steel, and interinterconnecting powerhouse buses. (5) 500 kCM: kCM: Main Main powerhou powerhouse se buses, buses, leads leads to the ground ground mat, generator generator step-up transform transformer er grounds, grounds, and surge arrester grounds. (6) 750-1,000 750-1,000 kCM: kCM: Main powerh powerhouse ouse buses buses or leads leads to the ground mat when larger sizes are needed. d. Misce Miscella llane neou ouss metal metal and and pipin piping g.
Powe Powerh rhou ouse se crane rails should be bonded at the joints with both rails being connecte connected d to ground. Roof trusses; trusses; draft draft tube gate guides; and miscellaneous structural steel, which may be exposed exposed to dangerous dangerous potentials potentials from energized energized circuits, circuits, should should be connecte connected d to the ground ground networ network. k. All piping piping systems should be grounded at one point if the electrical path path is contin continuou uous, s, or at more more points points if the piping piping syssystem’s electrical path is noncontinuous.
surfac surfacing ing or a ground grounding ing mesh mesh buried buried 12-18 12-18 in. below below grade grade should should be provid provided ed at each each discon disconnec nectin ting g switch switch handle handle.. The platfor platform m or mesh mesh should should be grounded grounded to the steel tower and to the ground network in two places. d. Grou Ground nded ed equi equipm pmen ent t . Grou Ground ndeed switc witchy hyar ard d equipm equipment ent includ includes es tanks tanks of circui circuitt breake breakers, rs, operat operating ing mechan mechanism ismss of discon disconnec nectin ting g switch switches, es, hinged hinged ends ends of disconnect disconnect grounding blades, transform transformer er tanks tanks and neutrals, surge arresters, cases of instrument transformers and coupling coupling capacitors capacitors,, and high-voltage high-voltage potheads. potheads. Isolated Isolated conduit conduit runs, power and lighting lighting cabinet enclosures, enclosures, and frames of electrically operated auxiliary equipment should also also be grou ground nded ed.. Sepa Separa rate te conduc conducto tors rs are used used for for grounding grounding surge arresters arresters to the ground network. network. Fences, Fences, including both sides of any gates, and other metal structures in the switchyard, should be grounded to the switchyard yard grid at inte interv rval alss of about about 30 ft. If the fence fence gate gatess open open outw outwar ard, d, a grou ground nd cond conduc ucto torr shal shalll be prov provid ided ed approx approxima imatel tely y 3 ft outside outside the gate gate swing swing radius. radius. Each Each switch switchyar yard d tower tower should should be ground grounded ed throug through h one leg. leg. All struct structure uress suppor supportin ting g buses buses or equipm equipment ent should should be grou ground nded ed.. If the networ network k does does not exte extend nd at leas leastt 3 ft outside outside the fence line, separate separate buried buried conductors conductors should be instal installed led to preven preventt a danger dangerous ous potent potential ial differ differenc encee between between the ground surface surface and the fence. fence. These conducconductors should be connected to both the fence posts and the ground network in several places. e. Overhe Overhead ad ground ground wires wires.
Overhe Overhead ad groun ground d wires wires should should be bonded bonded secure securely ly to the steel structur structuree on one end only and insulated on the other to prevent circulating current paths.
13-7. Grounding Grounding Devices Devices 13-6. Switchyard Switchyard Groundi Grounding ng a. Copper Copper conducto conductors rs.
A grid grid of copper copper condu conduct ctor orss should be installed beneath the surface of the switchyard to preven preventt danger dangerous ous potent potential ial gradie gradients nts at the surfac surface. e. The cables cables should should be large large enough enough and be buried buried deep enou enough gh for for prot protec ecti tion on from from mech mechan anic ical al dama damage ge.. The The cables’ cables’ current-c current-carry arrying ing capacity capacity under fault conditions conditions and and duri during ng ligh lightn tnin ing g disc discha harg rges es shou should ld be chec checke ked. d. Under all conditions, the grid serves to some extent as an electrode for dissipating fault current to ground. b. Grou Ground nd rods.
If warra warrant nted ed by soil soil condi conditi tion ons, s, a system of ground rods should be installed with the grid to provide maximum conductance to ground.
a. Cabl Cables es. Grounding Grounding cable cable used for direct direct burial burial or embedding in concrete should be soft-drawn bare copper. Sizes larger than No. 6 AWG should be stranded. b. Electr Electrode odess.
Elec Electr trod odes es for drivi driving ng shoul should d be copper copper-we -weld ld rods rods of approp appropria riate te diamet diameter er and length length.. Desired lengths can be obtained on factory orders. c. Exterior Exterior connections connections.
Ground Ground cable cable conne connecti ctions ons to driven driven ground ground rods, rods, any buried buried or embedd embedded ed connec connec-tions, or any exposed ground grid connections should be made either with an appropria appropriate te molded molded powdered powdered metal weld or by a copper alloy brazed pressure connector. d. Interi Interior or connec connection tionss.
c. Ground Grounding ing platfor platform m.
A grou ground ndin ing g plat platfo form rm conconsisting of a galvanized steel grating set flush in the gravel
Pres Pressu sure re clamp clamp (bolt (bolted ed)) type type termin terminal al lugs should should be used used for interio interiorr work. work. For neatness of appearance of interior connections, embedded
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EM 1110-2-3006 30 Jun 94 grou ground ndin ing g cabl cables es may may term termin inat atee on or pass pass thro throug ugh h grounding inserts installed with the face of the insert flush with the finished finished surface. surface. Connection Connection to the apparatus apparatus is made by bolting an exposed strap between a tapped hole on the insert and the equipment frame. Test stations stations should should be provide provided d for e. Test Test station stationss. Test measur measuring ing resist resistanc ancee of indivi individua duall mats mats and checki checking ng continuity continuity of interconne interconnecting cting leads. leads. Where Where measureme measurements nts are contem contempla plated ted,, the design design of the ground grounding ing system systemss should should avoid avoid interc interconn onnect ection ion of ground ground mats mats throug through h grounded equipment, overhead lines, and reinforcing steel. f. Embedded cable installation.
Embe Embedd dded ed gro groun und d cables cables must must be instal installed led so moveme movement nt of struct structure uress will will not sever or stretch the cables where they cross contraction tion join joints ts.. Suit Suitab able le prov provis isio ion n shou should ld be made made where where embedded cables pass through concrete walls below grade or water level to prevent percolation of water through the cable strands. g. Conduit Conduit . Ground Grounding ing conduc conductor torss run in steel steel conduit duit for mechan mechanica icall protec protectio tion n should should be bonded bonded to the cond condui uit. t. Cont Contro roll cabl cablee shea sheath thss shou should ld be grou ground nded ed at both both ends. ends. Signal Signal cable cable shields shields are grounde grounded d at one end only.
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EM 1110-2-3006 30 Jun 94
Chapter 14 Conduit and Tray Systems
14-1. 14-1. Genera Generall The conduit and tray system is intended to form a permanent pathway and to provide maximum protection for the conduc conductor tors. s. The system system design design should should allow allow for reasonreasonable expansion of the number of leads and circuits.
14-2. 14-2. Condui Conduitt a. Desi Design gn. Where Where practica practicable ble,, all conduit conduitss should should be concealed. concealed. In cases in which allowance allowance must must be made for circuits to future equipment, the conduit extension may be expose exposed. d. Connec Connectio tions ns to equipmen equipmentt should should not be made with flexible conduit if suitable connections can be made with rigid conduit.
(1) (1) Cond Condui uitt size size is dete determ rmin ined ed by the the type type of wire wire and number of circuits in the run, the length of run and the number and degree of bends in the run. (2) Where Where conduits conduits cross building building contraction contraction joints, the conduit runs should be perpendicular to the joint and expansion fittings, such as dresser couplings with grounding ing stra straps ps,, inst instal alle led d to prov provid idee for for move moveme ment nt of the the condui conduitt and to maintain maintain an unbroken unbroken ground ground path. The fitt fittin ing, g, inst instal alle led d on one one side side of the the cont contra ract ctio ion n join joint, t, should should be protec protected ted with with a suitab suitable le neopre neoprene ne sleeve sleeve to accommodate differential movement of the concrete. (3) Conduit Conduit should be installed installed in a manner to permit condensed condensed water water to drain whenever whenever possible. possible. When selfselfdrai draini ning ng is not not poss possib ible le,, a suit suitab able le drai drain n shou should ld be instal installed led in the low point point of the run. run. Thread Threaded ed joints joints in metal metal condui conduitt and termin terminati ations ons in cast cast boxes boxes should should be coat coated ed with with an appr approv oved ed join jointt comp compou ound nd to make make the the joints watertight and provide electrical continuity of the conduit system. (4) (4) The The cond condui uitt shou should ld prov provid idee a grou ground nd for for the the frames or housings of equipment to which it is connected, thereb thereby y provid providing ing a backup backup for the ground ground wire wire connec connec-tion tion to the main main ground grounding ing system. system. All conduit conduitss except except lighti lighting ng branch branch circui circuitt condui conduits ts should should be listed listed in the conduit and cable schedule.
b. Conduit Conduit types types.
(1) Rigid steel steel conduit should be hot-dip galvanized galvanized on insi inside de and and outs outsid idee surf surfac aces es,, conf confor ormi ming ng to ANSI ANSI C80.1. (2) For powerhouse powerhouse substructure substructure work, if conditions conditions are such that embedded galvanized conduit might rust out, considerat consideration ion should be given to installing installing exposed runs which can be replaced replaced.. Galvanized Galvanized conduit conduit buried buried in the switchyard should be protected with a coat of bituminous paint or similar material, unless experience at the particular site site has demons demonstra trated ted that that no specia speciall protec protectio tion n is needed on the galvanized conduit. (3) Unjacketed Unjacketed type type MC or type MV cables, meeting meeting the requirements of UL 1569 or UL 1072, may be used to avoid installing a cable tray carrying only a few conductors or where the installed cost would be substantially less than installin installing g rigid rigid steel steel conduit. Compatible Compatible connectors connectors should be used to bond the sheath to the ground system and to the equipme equipment nt served. served. The copper copper sheath sheath versio version n is pref prefer erab able le for for corr corros osiv ivee envi enviro ronm nmen ents ts.. MC or MV cables cables with with PVC insula insulatio tion n or jacket jacketing ing should should not be used. c. Boxes Boxes and cabi cabinet netss.
(1) The materials materials used used for boxes and cabinets cabinets should confor conform m to those used for the condui conduitt system system.. Cast Cast iron iron boxes should be used with galvanized conduit in embedded ded and and expo expose sed d loca locati tion onss at and and belo below w the the gene genera rato torr room room floo floorr leve level. l. Galv Galvan aniz ized ed shee sheett stee steell boxe boxess are are accept acceptabl ablee in locati locations ons above above the genera generator tor room room floor. floor. Suitab Suitable le extens extension ion rings rings should should be specif specified ied for outlet outlet boxes boxes in walls walls finishe finished d with with plaste plasterr or tile. tile. Large Large cabinets used for pull boxes, distribution centers, and terminal cabinets cabinets are usually usually constructe constructed d of heavy-gaug heavy-gauge, e, galvagalvanized sheet sheet steel. Because Because it is impractic impracticable able to galvanize galvanize large sheet metal boxes and fronts after fabrication without severe warping, galvanized steel sheets should be used in the fabrication fabrication.. Box corners corners should be closed by welds after bending, and the galvanizing repaired by metallized zinc spray. (2) If a cabine cabinett is embedde embedded d in a wall wall finished finished with plaster plaster or tile, tile, special special precautions precautions should be observed observed to ensure that the face of the installed cabinet is flush with
14-1
EM 1110-2-3006 30 Jun 94 the finishe finished d wall. wall. Front Front covers covers are general generally ly mounted mounted with with machin machinee screws screws throug through h a box flange flange drille drilled d and tapped tapped in the field field to facili facilitat tatee proper proper alignme alignment. nt. The requirements of UL 50 should be considered as minimum in the design of such cabinets. cabinets. Provision Provision should should be made for internal bracing of large cabinets to prevent distortion during concreting operations.
Cabl Cablee tray trayss are are fabr fabric icat ated ed from from extrud extruded ed alumi aluminum num,, formed formed sheet sheet metal, metal, or expand expanded ed metal. metal. Materi Material al costs for the expand expanded ed metal trays trays may be slig slight htly ly high higher er,, but but a grea greate terr sele select ctio ion n of join joinin ing g device devices, s, greate greaterr distan distance ce betwee between n suppor supports, ts, and specia speciall sections and fittings minimize field labor costs and generally result in lowest installed cost.
(3) Pull Pull boxes boxes for telephon telephonee circui circuits ts should should be large large enough enough to provid providee adequa adequate te space space for fannin fanning-o g-out ut and connecting cables to the terminal blocks.
c. Tray Tray supports supports. The The tray trayss are are inst instal alle led d on fabri fabri-cated galvanized steel supports designed and anchored to the powerh powerhous ousee walls walls and/or and/or ceilin ceiling g to provid providee a rigid rigid struct structure ure through throughout out.. In the cable cable spread spreading ing room, room, the tray supports may extend from the floor to the ceiling to give give the the nece necess ssar ary y rigi rigidi dity ty.. Supp Suppor orts ts simi simila larr to cabl cablee racks and hooks are suitable for supporting cable trays on cable cable tunnel tunnel walls. walls. If trays trays run throug through h the center center of a tunnel tunnel,, they they should should be suppor supported ted on struct structura urall member memberss such such as channel channel with with angle angle cross-pi cross-piece eces. s. Metal Metal tray sections tions 8 ft long long requir requiree suppor supports ts on 8-ft 8-ft center centers. s. Splice Splicess should should be made made at suppor supports ts to provid providee proper proper anchor anchorage age for the tray sections.
14-3. 14-3. Cable Cable Trays Trays a. Genera Generall. Cable Cable trays trays are common commonly ly used to carry carry groups groups of cables cables from from genera generatin ting g units, units, the switch switchyar yard, d, and access accessory ory equipm equipment ent that that termin terminate atess in the contro controll room. room. Trays in place of conduit provide provide flexibility, flexibility, accesaccessibili sibility, ty, and space economy economy.. Trays Trays are also also used used for the interconn interconnectin ecting g cables cables between between switchboar switchboards ds in the control trol room, room, and from from switch switchboa boards rds to the termin terminati ations ons of embedd embedded ed condui conduits ts runnin running g to equipmen equipment. t. Short Short runs runs of trays may be used to connect two groups of conduit runs where it is not practicable to make the conduit runs continuou tinuous. s. The designe designed d tray tray system system should should provide provide the maximum practicable segregation between control circuits and power power and lighti lighting ng circui circuits. ts. Approp Appropria riate te guidel guideline iness for for cabl cablee tray tray desi design gn cons consid ider erat atio ions ns are are cont contai aine ned d in IEEE 422.
14-2
b. Fabric Fabricatio ation n.
d. Cable Cable suppor supports ts. Split Split hardwoo hardwood d blocks blocks drilled drilled to
fit fit cabl cables es or acce access ssor orie iess for for the the meta metall tray trayss shou should ld be prov provid ided ed as nece necess ssar ary y to supp suppor ortt cabl cables es ente enteri ring ng and and leavin leaving g the trays. trays. The tray system system should should be designed designed to avoid long steep runs requiring anchoring of the cables to prevent movement.
EM 1110-2-3006 30 Jun 94
Chapter 15 Wire and Cable
15-1. 15-1. Genera Generall Wire and cable systems should be designed for long life with with a minimu minimum m of servic servicee interr interrupt uption ions. s. The material materialss and constr construct uction ion descri described bed in Guide Guide Specif Specifica icatio tion n CW16120 provide construction materials consistent with these servic servicee requir requireme ements nts.. IEEE IEEE 422 provides provides overall overall guidguidance in planning, designing, and installing wire and cable syst system emss in a powe powerr plan plant. t. Topi Topics cs covere covered d in the IEEE IEEE guide include cable performance, performance, conductor sizing, cable segregation systems, installation and handling, acceptance testing, testing, and other related subjects. subjects. Additional Additional guidance guidance is provided in EPRI EL-5036, Volume 4.
15-2. 15-2. Cable Cable Size Size The The mini minimu mum m size size of cond conduc ucto torr for for curr curren entt-ca carr rryi ying ng capacity should be based on the National Electrical Code (NEC (NEC)) requ requir irem emen ents ts for for 60 °C insu insula late ted d wire wire.. NEMA NEMA WC50 WC5 0 and WC5 WC51 1 provid providee ampaci ampacitie tiess for high-v high-volt oltage age cables cables and for multic multicond onduct uctor or cables cables not covere covered d in the NEC. NEC. Circui Circuitt voltag voltagee drop drop should should be checked checked to ensure ensure the total drop from the source to the equipment does not exceed requirements of Articles 210 and 430 of the NEC.
15-3. Cable System System Classificat Classification ion All cables cables or conduc conductor tors, s, except except lighti lighting ng system system branch branch circuits, should be listed in the conduit and cable schedule under the appropria appropriate te heading heading as either either power or control control cable. cable. Design Design of the cable cable systems systems is divided divided into three three classifications according to functions, as follows: a. Interior Interior distributi distribution on.
(1) Power Power and lighti lighting ng conduc conductor torss includ includee circui circuits ts from the station service switchgear to distribution centers or to statio station n auxili auxiliary ary equipm equipment ent;; branch branch circui circuits ts and contro controll circui circuits ts from from distri distribut bution ion center centerss to auxili auxiliary ary equipment; feeders to lighting panels; and lighting branch circui circuits. ts. No conducto conductorr size size smaller smaller than No. 12 AWG should be used, except for control circuits associated with heating heating and air-condition air-conditioning ing equipment equipment where No. 14 is adequate. (2) Multic Multicond onduct uctor or power power cables cables should should be used used for the larger and more important circuits such as feeders to distributi distribution on centers in the dam, the powerhouse, powerhouse, and the switchyard switchyard;; lighting lighting panels; panels; and any other major project
load loads. s. Sing Single le-c -con ondu duct ctor or wire wiress can can be used used for for bran branch ch circuits circuits and control control circuits circuits from distribut distribution ion centers centers to equi equipm pmen entt when when inst instal alle led d in cond condui uit. t. For For cabl cablee tray tray instal installat lation ions, s, Articl Articlee 318 of the Nation National al Electr Electric ic Code Code (NFPA 70-1993) dictates the use of multi-conductor tray rate rated d cabl cablee for for all all circ circui uits ts requ requir irin ing g No. No. 1 cabl cablee or smaller. b. Control Control and communica communication tion.
(1) Control Control cables include include station control control and annunannunciator ciator circui circuits ts from from the contro controll room room switch switchboa boards rds,, unit unit instrument boards, exciter cubicles, and secondary control center centers. s. Such Such circui circuits ts are generall generally y identi identifie fied d with with the DC control system, the instrument bus, or the annunciator system. system. All control control cables, except except those for the communicommunicati ation sys system tem and and spec speciial circ circui uitts not noted in para para-graph 15-3b(6), (6), should should comply comply with with the requir requireme ements nts of Guide Specification CW-16120. (2) (2) The The cabl cables es shou should ld be adeq adequa uate tely ly supp suppor orte ted d in long vertical runs and where they enter or leave the cable trays. trays. MultiMulti-con conduc ductor tor cables cables are usuall usually y No. 19/25 or 19/22 19/22 for contro control, l, meteri metering, ng, and relayi relaying ng circui circuits ts and No. No. 16 stra strand nded ed for for annu annunc ncia iato torr circ circui uits ts.. All All curr curren entt transf transform ormer er second secondary ary circui circuits ts should should be No. 19/22 19/22 or larger larger.. Larger Larger conduct conductor or sizes sizes may be requir required ed to take take care of voltage drop, or to decrease the burden on instrument transformers. (3) No splices should should be made between the terminal terminal points of the cable. (4) In selecting selecting cables, considerat consideration ion should be given to minimizing the number of different cable items ordered for installati installation on or stocked stocked for maintenance. maintenance. For example, example, the 4-, 6-, and 8-conductor cables might be omitted and 5-, 7-, and 9-cond 9-conduct uctor or cables cables substi substitut tuted, ed, leavin leaving g one spare spare conducto conductor. r. The practic practicee of includin including g one or more more spare conductors in each cable of more than four conductors is considere considered d desirable. desirable. Selection Selection of sizes and numbers of conductors per control cable should be limited, if possible, to combinations that have 50 ft or more in each item of a lot ordered. (5) All wiring wiring for the teleph telephone one system system,, includ including ing circuits from the main cabinet to the local telephone jacks, should be listed under “Telephone” cables in the schedule. Selection of telephone system conductors will be dictated by the application. (6) Special Special circuits circuits such as calibrated calibrated ammeter ammeter leads, and coaxia coaxiall cable cable circui circuits ts to carrie carrier-c r-curr urrent ent capaci capacitor tors, s, comput computer er networ networks, ks, microw microwave ave,, and video, video, should should be
15-1
EM 1110-2-3006 30 Jun 94 sche schedu dule led d unde underr cont contro roll cabl cables es or tele teleph phon onee cabl cables es,, whichever whichever is applicable. applicable. Clarifyin Clarifying g remarks concernin concerning g the the type type of the the cond conduc ucto torr and and the the supp suppli lier er shou should ld be included. included. Where fiber-opt fiber-optic ic cables are used, installation installation and applicati application on should should follow follow the manufactur manufacturer’s er’s recomrecommendat mendation ions. s. Two-co Two-condu nducto ctorr No. 19/25 control control cables cables may be used where the circuit lengths make it impractical to obtain obtain calibrate calibrated d leads with the instrumen instruments. ts. (7) (7) Anal Analog og and digita digitall sign signal al cable cables. s. Ther Theree is no standard standard specificat specification ion for these cables. cables. There are general general guidelines that should be followed in selecting the general charac character terist istics ics of the signal signal cable cable to be used. used. Some Some of these guidelines are: (a) PVC insulation insulation or jacketing jacketing may not be used. (b) (b) Insu Insula lati tion on and and jack jacket et mate materi rial al shou should ld pass pass UL flame tests.
b. Power Power circu circuits its.
(1) Each cable and conduit conduit should be identifie identified d with an indi indivi vidu dual al desi design gnat atio ion. n. The The cabl cablee and and cond condui uitt are are tagged with a designation at each end and at intermediate points points as necessary necessary to facilitate facilitate identificat identification. ion. The designation is also shown on equipment wiring diagrams, tray loading diagrams, on conduit plans and details, on cabinet layouts, and on junction and pull box layouts. (2) The scheduli scheduling ng of cables cables should should always always include include (opposite the cable designation) the following information: (a) Number Number and size of conducto conductor. r. (b) Function Function or equipmen equipmentt served. served. (c) Origin Origin and destinat destination. ion. (d) Routing Routing via conduits conduits and trays. trays.
(c) (c) Anal Analog og sign signal al cond conduc ucto tors rs must must be pair paired ed and and twis twiste ted d toge togeth ther er with with a shie shield ld,, sign signal al cond conduc ucto tor, r, and and return conductor in the same pair.
(e) Special Special conditio conditions. ns. (f) Estimate Estimated d length. length.
(d) Conduc Conductor tor pairs pairs should should be twiste twisted, d, variab variable le lay, lay, pairs individually shielded. (e) Multipair Multipair cables cables should have an overall shield shield and an outer jacket. (f) (f) Shie Shield ldss shou should ld be grou ground nded ed at one one end end only only to prevent shield current.
(3) The scheduling scheduling of conduit should include include (opposite the conduit designation) the following: (a) Size and and type of conduit conduit.. (b) Function Function or equipment equipment serviced. serviced. (c) Origin Origin and destinat destination. ion.
(g) (g) Cond Conduc ucto torr size size shou should ld be not not less less than than No. No. 18 AWG. (h) Minimum Minimum insulation insulation level level should be 150 V. Embe Embedd ddeed grou groun nding ding system system conduc conductor torss should should be strand stranded, ed, soft-d soft-draw rawn, n, bare bare copper copper wire wire follow following ing the recomm recommend endati ations ons of ChapChapter 13. 13. The cables cables need not be schedule scheduled, d, but if brough broughtt out in test test statio stations, ns, should should be suitab suitably ly tagged tagged for future future identification. c. Ground Grounding ing
conduc conductor torss.
15-4. Conduit and Cable Schedul Schedules es a. Genera Generall.
The The inten ntentt of the cond conduit uit and and cabl cablee schedule is to provide all pertinent information to assist in installing, connecting, identifying, and maintaining control and power power cables cables.. When When not includ included ed with the plans plans for constructi construction on bids, the specifica specifications tions indicate cable schedules will be furnished to the contractor.
15-2
(d) Special Special conditi conditions. ons. (e) Length Length.. (4) Conduit Conduit and cable should should have the same designadesignation if possible. possible. The number number assigned assigned should give inforinformati mation on abou aboutt the the serv servic icee rend render ered ed by the the cabl cable, e, the the termination points of the cable, and the approximate voltage or power classification. (5) (5) Gene Genera rall lly, y, each each cabl cablee betw betwee een n majo majorr unit unitss of equipment or from major units of equipment in the powerho erhous usee to stru struct ctur ures es exte extern rnal al to the the powe powerh rhou ouse se is assigned a number made up of three parts, as follows: (a) (a) The The firs firstt part part of the the cabl cablee numb number er show showss the the beginn beginning ing of each each cable cable run and is compos composed ed of upperuppercase letters and numerals assembled into a code to represent sent the variou variouss major major units units of equipm equipment ent,, switch switchgea gear, r,
EM 1110-2-3006 30 Jun 94 swit switch chbo boar ards ds,, powerhouse.
cabi cabine nets ts,,
etc. etc.,,
loca locate ted d
thro throug ugho hout ut the the
(b) The second second part of the cable number number is composed composed of a single lower-case lower-case letter letter and number. number. The letter letter indicate catess the the type type of serv servic icee rend render ered ed by the the cabl cable, e, i.e. i.e.,, power, alarm, etc., while the number serves to differentiate betwee between n cables cables of a partic particula ularr type type runnin running g betwee between n two points. (c) (c) The The thir third d part part of the the cabl cablee numb number er show showss the the term termin inat atio ion n of each each cabl cablee run run and and is comp compos osed ed in the the same manner as the first part of the cable number. Example: Example: Cable Number Number Cable ID: SC-u3-G1 SC-u3-G1 Breakdown: Breakdown: SC = Start of cable cable run (Main (Main contr control ol switchboard) u = Type of of service service (Annunc (Annunciato iatorr lead) 3 = Number Number of of such such cable cable (3rd (3rd annunciator lead cable to Generator No. 1; there might be 6 or 9 cables, for example, each with its own number) G1 = Terminatio Termination n of cable (Generat (Generator or No. 1) (6) Cables Cables betwee between n low-vo low-volta ltage ge equipm equipment ent (such (such as motor control centers) and minor units of equipment (such as station auxiliaries) have no code letter and numeral to show show the termin terminati ation on of the cable cable run. The cable cable numbers bers in these these cases cases are made made of only only two parts. parts. The first first part indicates the start of the cable run, while the second part indicates the type of service rendered by the cable. Example: Example: Cable Number Number Cable ID: CQ5-c12 CQ5-c12 Breakdown: Breakdown: CQ5 = Start of cable cable run (480-V (480-V load center No. 5) c = Type of service (Control circuit) 12 = Circuit number number (7) Number Numberss are assigne assigned d to the power power and control control cab cables les so the the power ower circ circui uitt of a give given n num number ber is
contro controlle lled d by a contro controll circui circuitt having having the same same number number,, the differentiati differentiation on being only in the code letter letter designadesignation of the circuit circuit duty. As an example, cable cable “CQ5-c12” would be the control for power circuit “CQ5-q12.” (8) (8) Ther Theree are are case casess wher wheree a circ circui uitt term termin inat ates es at severa severall duplic duplicate ate device devices. s. For instance instance,, an annunc annunciat iator or circuit runs to a junction box and is spliced at this point with branches running to a thermostat in each tank of a tran transf sfor orme merr bank bank.. In such such a case case,, the the cabl cablee from from the switch switchboa board rd may have have a design designati ation on such such as S1-u2S1-u2-T1 T1 and the branch branch designati designations ons are S1-u2.1-T1, S1-u2.1-T1, S1-u2.2-T1, S1-u2.2-T1, and S1-u2.3-T1. (9) Spare Spare condui conduits ts are numbered numbered by using using a threethreepart part numb number er wher wheree poss possib ible le.. In case casess wher wheree the the spar sparee conduits leave a certain switchboard or distribution center and are stubbed at the end of the building, only a two-part numb number er can can be used used,, e.g. e.g.,, CQ01 CQ01-s -s1 1 is a spar sparee cond condui uitt leaving motor control center CQ01. c. Lighting Lighting circuit circuitss.
(1) Numbering Numbering of the circuits circuits and conduits conduits for lighting ing circ circui uits ts is simi simila larr to the the powe powerr circ circui uitt numb number erin ing g scheme. scheme. Each cable cable is assigned a three-part three-part number number such as SR1-r3 SR1-r3-CR -CR4. 4. Full Full inform informati ation on for these these condui conduits ts and circui circuits ts is given given on lighti lighting ng drawin drawings. gs. Circui Circuits ts from from the lighti lighting ng cabine cabinets ts receiv receivee number numberss corres correspon pondin ding g to the switch switch numbers numbers in the lighting cabinets. cabinets. (2) The lighti lighting ng drawin drawings gs indica indicate, te, betwee between n each each outlet outlet,, the condui conduitt size, size, number number of conduc conductor tors, s, and the size size of the the cond conduc ucto tors rs.. The The numb number er of cond conduc ucto tors rs is indicated indicated by drawing drawing small small lines across the conduit, conduit, one line line for each each conduc conductor tor.. At the side of each each outlet outlet,, there there is a small number indicating the circuit to which the outlet is connected, another number at the side of the outlet indicating the size of the lamp to be installed if not covered elsewhere elsewhere.. Where the conduit conduit leaves the first first outlet to run to the lighting cabinet, the circuit numbers of the conductors in the conduit are indicated. d. Code letter letter identifica identification tion.
(1) General. General. Code letters letters are are broken broken down into into three three classes: classes: terminal terminal equipment, equipment, modifying modifying terms terms for terminal equipment, equipment, and cable service service classificati classification. on. Code letters letters and explanations are given in Table 15-1 below.
15-3
EM 1110-2-3006 30 Jun 94 Table 15-1 Code Letters for Conduit and Cable Terminal Equipment • Operator’s Operator’s desk, switchboard switchboards, s, and switchgear switchgear SA SAT SAT S SB SC SCC SG SL SO SOC SJ SP SQ SH ST SU SR SX GN OD CC ER MUX MW FSC DOC ROC FSP FCP FSQ FSU TF
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Fishwa Fishwater ter Genera Generator tor Switch Switchboa board rd Satell Satellite ite Digital Digital Proces Processor sor Gene Genera rator tor Swit Switch chbo boar ard d (Add (Add No.) No.) Batter Battery y Swit Switch chbo boar ard d Main Main Contr Control ol Switc Switchb hboa oard rd Main Main Con Contro troll Cons Console ole Graphi Graphic c Instru Instrumen mentt Switch Switchboa board rd Load Load Cont Contro roll Swit Switch chbo boar ard d Station Station Servic Service e Switch Switchboa board rd System System Operations Operations Controller Controller 13.8 kV Switchgear (Add No.) 4160 4160 V (or (or 2400 2400 V) Swit Switch chge gear ar 480 480 V Switc Switchg hgea earr (Add (Add No.) No.) Heatin Heating g Switc Switchg hgea earr Sta Status tus Boa Board Moto Motorr Con Contr trol ol Cent Center er (Add (Add No.) No.) Ligh Lightin ting g Swit Switch chge gear ar Excita Excitation tion System System Equipm Equipment ent (Add (Add No.) No.) Gene Genera rator tor Neut Neutra rall Oper Operat ator or’s ’s Desk Desk Carrie Carrierr Curren Currentt Equipm Equipment ent Electr Electrica icall Equipm Equipment ent Roo Room m Cab Cabine inets ts Multip Multiplex lexer er Microw Microwave ave Termin Terminals als Fishwa Fishway y Switc Switchbo hboard ard Digital Digital Operations Operations Controller Controller Remote Remote O Operat perations ions Controller Controller 4160 416 0 V Fishwa Fishway y Swit Switchg chgear ear 4160 416 0 V Fishwa Fishway y C Cont ontrol roller ler 480 V Fish Fishway way Switch Switchgea gearr Fishwa Fishway y Unit Unit Swit Switchg chgear ear Tele Teleph phon one e Fram Frame e
• Load centers centers CP CQ CR CD CE CF CA CH CY DQ FCP FCQ FCQ PQ
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4160 4160 V (or (or 2400 400 V) 48 480 V 120/2 120/240 40 V (120 (120/2 /208 08 V) 4 8 V DC 1 25 25 V DC 2 50 50 V DC Emerge Emergenc ncy y Ligh Lighti ting ng Pref Prefer erre red d AC (CO2) Cabinet 480 480 V (Da (Dam) 4160 416 0 V (or 240 2400 0 V) V) Fish Fishway way 480 480 V (Fis (Fishw hway ay)) 480 480 V (Pro (Proje ject ct))
• Apparatus Apparatus A B G GF X
-
Act Actua uato torr (Gov (Gover erno nor) r) Battery Generator Fishwa Fishwate terr Gene Genera rator tor Brea Breake kerr (Add (Add Volt Voltag age e Lett Letter er))
T Z CT V EG MG MC M PT K FT
Tran Transf sfor orme merr (pow (power er)) Discon Disconnec nectin ting g Switch Switch (Add (Add Voltag Voltage e Letter Letter)) Curren Currentt Transf Transform ormer er Volta Voltage ge Tran Transf sfor orme merr Engi Engine ne Gene Genera rato torr Moto Motorr Gene Genera rator tor Motor Mot or Con Contro troll Cab Cabine inett Motor Potent Potential ial Transfo Transforme rmerr (Separ (Separate ate Apparat Apparatus us modified modified by voltage as PTW) - Crane - Fish Fishwa way y Tran Transf sfor orme merr
• Miscellane Miscellaneous ous terminal terminal equipment, equipment, boxes, or structure structures. s. Some items items in this this list list are used for cable cable and condui conduitt termin terminals als,, but a majority are used only as modifying suffixes for devices on schematic diagrams: AA AH AN AQ AR AS BC BG BK BU BV CAC CJB CM CPD CTC DP DS DT DWP EA EC EF EH EHQ EL EP ETM EV FM FP FS FTC FW FWG GH GI GP GW HC HD HF (Continued)
15-4
-
-
Govern Governor or Air Com Compre presso ssorr Air Hor Horn Annu Annunc ncia iato torr Gove Govern rnor or Oil Oil Pump Pump Annu Annunc ncia iato torr Rese Resett Amme Ammete terr Switc Switch h Batte Battery ry Char Charge gerr Brea Break k Glas Glass s Stat Statio ion n Br Brakes Bubb Bubble lerr Syst System em Bypass Bypass Valve Valve or Butter Butterfly fly Valve Valve Central Central Air Air Conditio Conditioner ner Junction Junction Box, Box, Master Control Control Circui Circuits ts (Modify (Modify by Unit Unit No.) Channe Cha nnell Man Manome ometer ter Capacitance Capacitance Potential Potential Device Device Control Control Termina Terminall Cabinet Cabinet Drai Draina nage ge Pump Pump Deck Deck Stat Statio ion n Differentia Differentiall Transmitter Transmitter (Transduce (Transducer) r) Domestic Domestic Water Water Pump Sewa Sewage ge Aera Aerato torr Efflue Effluent nt Com Commin minuto utorr Exha Exhaus ustt Fan Fan Elec Electr tric ic Heat Heater er Electric Electric Oil Heater Heater Ele Elev vato ator Sewage Sew age (Efflu (Effluent ent)) Pump Pump Elapse Elapsed d Time Time Meter Meter Electr Electrica ically lly Operat Operated ed Valve Valve Flow Flow Mete Meterr Fir Fire Pump ump Float Float Switch Switch (Devic (Device e 71 prefer preferred red)) Fishway Fishway Terminal Terminal Cabinet Cabinet Floa Floatt Well Well Forebay Forebay Water Water Level Gage Gage Gene Genera rator tor Heat Heater er Groun Ground d Inse Insert rt Grea Grease se Pump Pump Generator Generator Cooling Cooling Water Water (Pump (Pump or Valve) Valve) Head Head Cove Coverr Sump Sump Pump Pump Air Con Conditi ditioni oning ng Dam Damper per Air Con Conditi ditioni oning ng Air Air Filt Filtrat ration ion Equipm Equipment ent
EM 1110-2-3006 30 Jun 94 Table 15-1. 15-1. (Concluded) (Concluded) HH HP HQ HR HV HW HY IG IM IS IQ IV JB LC LT LTH LTH LTU LTU MO MOD OR OS PA PB PC PG PH PR PS
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PT PV QPD QPL QPT RC RF RW SD SF SN SO TA TB TBA TBD TC TD TE TH TM TP TQ TS TWG UAC ULC US UV UW VQ
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Air Con Condit dition ioning ing System System Hum Humidi idifie fierr High High Pressu Pressure re Thrust Thrust Bearin Bearing g Oil Pump Pump Conditi Con ditioni oning ng System System Oil Pump Pump Air Con Condit dition ioning ing System System Refrig Refrigera eratio tion n Pump Pump Air Con Condit dition ioning ing System System,, Mast Master er Device Devices s Air Con Condit dition ioning ing System System Water Water Pump Pump Hyp Hypoc ochl hlor orin inato atorr In Int ak ake Gate Inta Intake ke Mano Manome mete terr Intr Intrud uder er Dete Detect ctor or Syst System em Inta Intake ke Gate Gate Oil Oil Pump Pump Inverter Junc Juncti tion on Box Load Load Cont Contro roll Cabi Cabine nett Outs Outsid ide e Ligh Lightin ting g (480 (480 V) High High Bay Bay Ligh Lightin ting g Line Line Tuni Tuning ng Unit Unit Load Load Cont Contro roll Mast Master er Motor Operated Operated Disconnec Disconnectt Oper Operat atio ions ns Reco Record rder er Load Loa d Cont Control rol Statio Station n Oper Operati ation on Select Selector or Statio Station n (Plant (Plant)) Air Com Compre presso ssorr Pull Pull Box Box or Push Pushbu butt tton on Progra Program m Cont Contro roll ller er Penst Penstoc ock k Gate Gate Powe Powerh rhou ouse se (Add (Add No.) No.) Proj Projec ectt Buil Buildi ding ng Pot Poten enti tial al Sele Select ctor or or Pres Pressu sure re Swit Switch ch (Dev (Devic ice e 63 preferred for pressure switch) Pres Pressu surre Tank Tank Penst Penstoc ock k Valv Valve e Oil Transf Transfer er Pump Pump (Dirty (Dirty)) Oil Transf Transfer er Pump Pump (Lub (Lube) e) Oil Transf Transfer er Pump Pump (Trans (Transil) il) Code Code Call Call Rela Relay y Box Box Reci Recirc rcul ulat atin ing g Fan Fan Raw Raw Wate Waterr Pump Pump Servo Servo or Shaft Shaft Oil Catche Catcherr Drain Drain Pump Pump S up upply Fan St Stop Nut Load Loa d Con Contro troll System System Select Selector or Transf Transform ormer er Coo Coolin ling g Equipm Equipment ent Air Syste System m Tele Teleph phon one e Box Box or Test Test Bloc Block k Turbin Turbine e Beari Bearing ng Oil Oil Pump Pump - AC AC Turbin Turbine e Beari Bearing ng Oil Oil Pump Pump - DC Term Termin inal al Cabi Cabine nett Trans Transfo form rmer er Delu Deluge ge Thermo Thermosta statt (Heat (Heating ing & Venti Ventilat lation ion Equipm Equipment ent Draw Drawing ings) s) Pref Prefer erre red d AC Tran Transf sfor orme merr Tailra Tailrace ce Mano Manome mete terr T ur urbine Pit Transf Transform ormer er Coo Coolin ling g Equipm Equipment ent Oil Pump Pump Tes Test Stat Statio ion n Tailwa Tailwater ter Level Level Gage Gage Unit Unit Air Con Condit dition ioner er Unit Unit Load Load Con Contro troll Sele Selecto ctorr Unit Unit Sele Select ctor or Unloa Unloade derr Valv Valve e Unwa Unwate teri ring ng Pump Pump Valve alve Oil Oil Pump ump
XA XF VS WG WH WP WV
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Circui Circuitt Brea Breaker ker Air Com Compre press ssor or Circui Circuitt Break Breaker er Coo Coolin ling g Fan Voltm Voltmet eter er Swit Switch ch Water Water Gate Gate (Sluic (Sluice, e, Weir, Weir, etc. etc.)) Water Water Heate Heaterr (Hot (Hot Water Water Tank Tank or Boile Boiler) r) Gate Gate Wash Wash Pump Pump - Deck Deck Wash Wash Pump Pump Water Water Valv Valve e Modifying terms for terminal equipment
• As an aid to further further identification identification of voltage class class and location location of the equ equipm ipment ent,, the follow following ing letter letters s are app applie lied d to separa separatel tely y mounted mounted breakers, breakers, disconnect disconnecting ing switches, switches, current current transformer transformers, s, and voltage transformers: U M W J P Q R F E D H
-
500 kV 230 kV 115 kV 13.8 kV or 7.2 kV 416 4160 V (or (or 2400 2400 V) 480 V 120/ 120/24 240 0 V (120 (120/2 /208 08 V) 25 250 V DC 12 125 V DC 48 48 V DC 120 120 V Prefe referrred red AC
• Other modifyi modifying ng terms terms O N Y
- (as (as GO, GO, TO) TO) - Stat Statio ion n Serv Servic ice e - (as (as GN1, GN1, TN1) TN1) - Neut Neutra rall - (as CY for CO2 Cabinet) - CO2 Service classification
a c
d e f h j m p q r s tr t ts u
uc v ut x
- Curr Curren entt Tran Transf sfor orme merr - Shun Shuntt Lead Leads s - Con Contro troll Circui Circuits, ts, (Cir (Circui cuitt Breake Breakerr Contro Controll Circui Circuits, ts, Exci Excitatation tion Syst System em Cont Contro roll Circ Circui uits ts,, and and Gove Govern rnor or Cont Contro roll Circuits) - 0 - 48 V DC - Powe Powerr Circ Circui uit, t, 125 125 V DC - Powe ower Circ ircuit, uit, 250 250 V DC - 120 120V Prefe referr rred ed AC - Power Circuit, 13.8 kV AC - Powe Powerr Circ Circui uit, t, 230 230 kV AC - Powe Powerr Circ Circui uit, t, 4160 4160 V or 2400 2400 V AC - Powe Powerr Circ Circui uitt 480 480 V AC - Pow Power er Circui Circuitt (Light (Lighting ing)) 120 120/24 /240 0 V or 120 120/20 /208 8 V AC - Sp Spare Condui t - Radi Radio o Circ Circui uits ts - Teleph Telephone one Circui Circuits, ts, Inte Interco rcommu mmunic nicati ation on Circui Circuits ts - Soun Sound d Powe Powerr Circ Circui uitt - Alar Alarm m Circ Circui uits ts;; Annu Annunc ncia iato torr Circui Circuits ts;; Wate Waterr Flow Leve Level; l; Pressu Pressure; re; and Temper Temperatu ature re Indica Indicatin ting g and Record Recording ing Circuits; Telemetry, Analog, Operations Recorder, etc. - Code Code Call Call Circ Circui uits ts - Volta Voltage ge (Pot (Poten enti tial al)) Tran Transf sfor orme merr Seco Second ndar arie ies s and and DC Voltage Leads - Carr Carrie ierr or Pilo Pilott Wire Wire Circ Circui uitt - Exci Excita tati tion on Circ Circui uits ts
15-5
EM 1110-2-3006 30 Jun 94 e. Code identific identification ation notes notes.
(1) The list of letter letterss in paragrap paragraph h 15-4 15-4 d (1) ( 1) is used used for separately separately mounted mounted apparatus apparatus only. Instrumen Instrumentt transformers formers and disconnec disconnecting ting switches switches are given individual individual designations only if they are mounted by themselves, as in an outdoor structure or in a similar indoor arrangement. (2) (2) Ins Instr trum umen entt tran transf sfor orme mers rs and and disc discon onne nect ctin ing g switches switches mounted on a circuit circuit breaker or circuit circuit breaker struct structure ure have have the cable cable and condui conduitt design designati ations ons of the breaker. breaker. For example, example, bushing-t bushing-type ype current transform transformers ers and potential devices mounted on oil circuit breaker XJ3 have cable and conduit designations such as “S3-a1-XJ3” and “S3-v1-XJ3” (3) Cable terminal terminal designation designationss are used to designate major major assemblies assemblies such as a switchgear switchgear assembly assembly and not an indivi individua duall breake breakerr within within the switch switchgea gear. r. Indivi Individua duall breake breakerr design designati ation on is desira desirable ble,, but includ including ing it in the termi terminal nal design designati ation on (first (first term term of cable cable code) code) would would compli complicat catee the system system impair impairing ing its useful usefulnes ness. s. Thus, Thus, instru instrumen mentt transf transform ormers ers,, breake breakers, rs, and discon disconnec nectin ting g switches mounted in a switchgear or switchboard take the termi terminal nal design designati ation on of the switch switchgea gearr or switch switchboa board. rd. For example, a breaker mounted in a 480-V switchboard has a cable and conduit designation of “SQ” for the first term term and even though though the breake breakerr may have a number number,, this number is disregarded in the first term of the cable code. code. Where Where there there are only a few breake breakers, rs, the lack lack of a more positive identification is not objectionable. (4) Wh Wheen a swit switch chbo boaard has has a large arge num number ber of breakers, considerable time may be consumed in locating the cable. cable. To overcome overcome this objection, objection, the second second term of the cable code is numbered to correspond with the breaker number number.. For example example,, CQ2-q8 CQ2-q8 and CQ2-q2 CQ2-q25 5 are 480-V 480-V power power circuits circuits connecte connected d to breake breakerr No. 8 and No. 25, resp respec ecti tive vely ly,, in 480480-V V cabi cabine nett No. No. 2. No diff diffic icul ulty ty is encountered because the number in the second term serves to differentiate one cable from another and doesn’t indicate the total number of cables from a point. (5) (5) The The orde orderr of term termin inal al desi design gnat atio ion n foll follows ows the the order order given given in the code. For exampl example, e, a cable cable between between a lighting lighting switchboard switchboard and a lighting lighting cabinet cabinet is designate designated d as “SR2-r4“SR2-r4-CR5 CR5.” .” The switchbo switchboard ard table table preced precedes es the load center table, the switchboard switchboard designatio designation n being the first first term and the load center center the last last term. term. Other Other examexamples ples would would be SJ-j2SJ-j2-G1 G1 and CP-p1 CP-p1-K -K2. 2. This This order order of design designati ation on is mainta maintaine ined d for items items of the same same table; table; e.g., SC-a1-SP or A2-c1-G2.
15-6
(6) Becaus Becausee of the compli complicat cated ed code, code, the design designaation tion’s ’s prim primar ary y appl applic icat atio ion n is in the the powe powerh rhou ouse se.. The The same same design designati ation on may be used used with with a prefix prefix to signif signify y location location at a different different feature feature of the project. For example, example, DCR can represent a lighting cabinet in the dam. (7) Simila Similarly rly,, FCQ repres represent entss a fish fish facil facility ity 480-V 480-V contro controll center center.. This This system system is maintain maintained ed at the powerpowerhouse for terminal equipment, cables, and conduits servicing ing the the fish fishwa way y next next to the the powe powerh rhou ouse se and and also also is maintained maintained partiall partially y at the fishway. fishway. However, However, on portions portions of the fishwa fishway y includ including ing collec collectio tion n channe channels, ls, diffus diffusion ion cham chambe bers rs,, and and the the vari variou ouss gate gates, s, it is desi desira rabl blee to use use designatio designations ns employed employed in the structural structural and mechanica mechanicall design design and having having name familia familiarit rity. y. Design Designati ations ons and locations locations of these elements elements of fish facilities facilities are projectprojectspecific. (8) (8) Cabl Cablee runn runnin ing g from from one one part part of the the proj projec ectt to anothe anotherr should should be clearl clearly y identi identifie fied. d. For instanc instance, e, the 4160-V cables originating at the powerhouse and used to supply power for the fishway, dam, and lock may have a designation SP - p1 to the first point of connection, SP p1.1 betwee between n the first first and second second points points of connec connectio tion, n, and SP - p1.2, and so on, for the subsequent points. (9) Powerhouse Powerhouse drawings drawings showing the cable running running to the fishway should indicate the cable number and give reference to the fishway drawing in which the other terminal of the cable cable is shown. shown. Simila Similarly rly,, the fishwa fishway y drawdrawings ings should should indica indicate te the cable cable number numberss for the cable cable in both directions directions and reference referencess given to both powerhouse powerhouse and dam drawings. (10) (10) Wiri Wiring ng diag diagra rams ms for for a larg largee swit switch chbo boar ard d or switchgear switchgear assembly assembly are on several drawings, drawings, so considconsiderable erable time time is consum consumed ed in locati locating ng the proper proper drawin drawing g and and the the prop proper er panel. panel. To avoi avoid d this this diffic difficul ulty ty,, each each switchboard has its front panels numbered in order from left left to right. right. The panel panel design designati ation on is the switchb switchboar oard d designation followed by the panel number, and the cable number number then designates designates the panel at which it terminat terminates. es. For exampl example, e, on Genera Generator tor Switch Switchboa board rd No. 1, the third third pane panell from from the the left left would would be desi design gnat ated ed “S13 “S13”” and and a cable running from this panel has a designation such as, “S13-c1-TO.” (11) (11) In duplex duplex switchbo switchboard ards, s, a rear rear panel panel is desigdesignated by the letter “R” followed by a number corresponding ing to its its front ront pane panell. For For exam exampl plee, on Gene Generrator ator Switc Switchb hboa oard rd No. No. 1, the the thir third d rear rear pane panell from from the the righ rightt
EM 1110-2-3006 30 Jun 94 (facing the front of the rear panels) is designated “S1R3” and and a cabl cablee runn runnin ing g from from this this pane panell has has a desi design gnat atio ion n such as “S1R3-c1-TO “S1R3-c1-TO.” .” (12) Some vertical vertical sections sections of a motor motor control center center assembly may include two or more lighting panels, in one instance instance with the same voltage classificati classification on (e.g., CR-r and CA-r). The lighting lighting panel designati designation on is used in lieu of the the vert vertic ical al sect sectio ion n numb number er in thes thesee inst instan ance ces. s. A motor control control center center could could include include lighting lighting panels of the following designations: SU1 - - - CR11, CE11, CF11, CA11, CB11 SU2 - - - CR21, CE21, CF21, CA21, CB21 SU3 - - - CR31, CE31, CF31 CA31, CB31 SU4 - - - CR41, etc. f. Lighting circuits. With lighting lighting circuit circuits, s, it is desirdesir-
able to deviate from the general plan of providing a relationsh tionship ip betwee between n the condui conduitt and its contai contained ned circui circuits. ts. Branch Branch circui circuits ts from from lighti lighting ng cabine cabinets ts are number numbered ed to comply comply with the power circui circuitt guide. guide. The numberi numbering ng of branch conduits from lighting cabinets complies with the guide, except the conduit number bears no relationship to the numbers numbers of the circuit circuitss runnin running g throug through h it. The conduit number is initially initially determined determined by sequence sequence numbernumbering in a clockw clockwise ise direct direction ion from from the upper upper rightright-han hand d corner when facing the lighting cabinet and is not affected by circ circui uits ts and and cond condui uits ts feed feedin ing g the the ligh lighti ting ng cabi cabine net. t. Where more than one row of knockouts is involved, the sequ sequen encce of numb umberi ering is from from fron frontt to bac back and and clockwise.
15-7
EM 1110-2-3006 30 Jun 94
Chapter 16 Procedure for Powerhouse Design
16-1. Design Initiation Initiation Design Design for a powerhouse powerhouse is initiate initiated d during during engineeri engineering ng and design design activitie activitiess supporting supporting preconstr preconstructio uction n planning planning studies. studies. The planning planning studies accompany accompany reports reports to Congres gresss seek seekin ing g init initia iall auth author oriz izat atio ion n for for a proj projec ect. t. The The accompanying studies are either reconnaissance reports or feasibilit feasibility y studies with an engineeri engineering ng appendix. appendix. If favorable congressional action is received as a result of initial author authoriza izatio tion n activi activitie ties, s, furthe furtherr engine engineeri ering ng and design design activities are conducted including preparation of a General Design Design Memorandum Memorandum (GDM). (GDM). The GDM is incorporated incorporated into documentation submitted to higher authority seeking a cons constr truc ucti tion on star start. t. ER 1105 1105-2 -2-1 -100 00 prov provid ides es furt furthe herr informati information on on the contents contents of these reports. reports. Chapter Chapter 17 descri describes bes requir requireme ements nts for the GDM. At each stage stage of the process, process, powerhouse powerhouse design is further further refined. refined.
16-2. Design Process Process After After a projec projectt has been been author authorize ized d and funds funds approp appropririated ated or allo allott tted ed for for desi design gn of the the powe powerr plan plant, t, crit criter eria ia outlin outlined ed in Guide Guide Specif Specifica icatio tion n CE 4000, 4000, Append Appendix ix A, should should be follow followed ed regard regardles lesss of the organi organizat zation ion perperform formin ing g the the desi design gn.. The The crit criter eria ia outl outlin inee a proc proces esss of preparation of Feature Design Memorandums covering the design design featur features es of the power power plant, plant, prepar preparati ation on of plans plans and and spec specif ific icat atio ions ns,, and and othe otherr engi engine neer erin ing g acti activi viti ties es involved involved in implemen implementing ting design, constructi construction, on, and commissionin missioning g of the power plant. The field operatin operating g activity (FOA) (FOA) can utiliz utilizee either either the Hydroe Hydroelec lectri tricc Design Design Center Center (HDC) (HDC) or an archit architect ect engine engineer er (A-E) (A-E) to provid providee the engineering and design services for developing powerhouse design, preparing preparing plans and specifica specifications tions,, reviewreviewing vendor drawings, assisting in preparation of operation and maintenan maintenance ce manuals, manuals, and providing providing record drawing drawing documentation.
16-1
EM 1110-2-3006 30 Jun 94
Chapter 17 General Design Memorandum
17-1. Requirement Requirements s Format Format and content requirements requirements for the General Design Design Memora Memorandu ndum m (GDM) (GDM) are descri described bed in ER 1105-2 1105-2-10 -100. 0. The genera generall featur features es of the select selected ed power power plant plant design design are presen presented ted and analyz analyzed ed by means means of sketch sketches, es, diadiagrams, grams, and cost cost compar compariso isons. ns. Sketch Sketches, es, diagram diagrams, s, and cost comparisons are used to explain plan formulation and the the plan plan sele select ctio ion n proc proces ess. s. The The elec electr tric ical al draw drawin ings gs requir required ed for the memora memorandu ndum, m, in additi addition on to equipm equipment ent locations shown on general floor plans, consist chiefly of one-line one-line diagrams. diagrams. Approximat Approximately ely six to eight drawings drawings are sufficient sufficient to show main unit and switchyard switchyard connections, tions, the station service scheme, the control control and protective relaying schemes, the communications system, and a lighti lighting ng feeder feeder scheme. scheme. Major Major equipm equipment ent informat information ion,, obtained from vendors, should be included in the appendixes. dixes. If the report report is approved approved,, it becomes becomes a guide for subseq subsequen uentt detail detailed ed engine engineeri ering ng develo developed ped in Featur Featuree Design Design Memora Memorandu ndums ms and design design drawin drawings gs (cover (covered ed in Chapter 18).
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EM 1110-2-3006 30 Jun 94
Chapter 18 Feature Design Memorandums and Drawings
18-1. Design Memorandu Memorandum m Topics and Coverage Coverage Following approval of the General Design Memorandum, engi engine neer erin ing, g, desi design gn,, and and draw drawin ing g prep prepar arat atio ion n for for the the power plant proceed using Feature Design Memorandums (FDM) and accompanyi accompanying ng drawings. drawings. A completion completion schedul dule for for each ach of the the plann lanned ed memo memorrand andums ums and a sequence of submission is developed for the concurrence and approv approval al of the field field operat operating ing activi activity ty (FOA) (FOA) and higher higher authorit authority y early early in the process process.. Design Design memoran memoran-dum sequence and submission dates should be coordinated with the power plant construction schedule and equipment procureme procurement nt schedules. schedules. Timing Timing and sequence of submission sion are schedu scheduled led to maximi maximize ze review review time time and allow allow effe effect ctiv ivee use use of engi engine neer erin ing g reso resour urce cess of the the revi review ew agency.
18-4. Design Drawings Drawings Design drawings accompanying an FDM will conform in genera generall to the requir requireme ements nts mentio mentioned ned in the follow following ing paragraphs. a. Genera Generator torss.
No desig design n draw drawin ings gs are neces necessa sary ry for generators, unless needed to depict unusual generator lead arrangements, arrangements, or illustrate illustrate connections connections to and location of excitation equipment. b. Transformer Transformerss. Design Design drawings drawings for either either generagenerator step-up or station service transformers are not required with FDM submission. c. High-vo High-voltag ltagee system system. Draw Drawin ings gs loca locati ting ng the the switch switchyar yard d with with respec respectt to the powerh powerhous ouse, e, depict depicting ing cable tunnel or cable duct locations, and providing details on bay widths, types of structures, and phase-to-phase and phase-tophase-to-groun ground d clearances clearances should be furnished. furnished. A plan of the switchyard, including line bay and transformer bay sectio sections ns and a switch switchyar yard d one-li one-line ne diagra diagram, m, will will adeadequately quately convey convey the design design intent. intent.
18-2. Feature Feature Design Memorand Memorandums ums FDMs are normally prepared for electrical equipment and syst system emss purc purcha hase sed d by the the Gove Govern rnme ment nt.. They They are are also also prepared prepared for electrica electricall systems systems having having a significan significantt content of GovernmentGovernment-furni furnished shed equipment equipment.. The plans and specifications required for purchased equipment are based on the design parameters and information contained in the FDM. FDM. Typica Typicall equipm equipment ent and system systemss requir requiring ing FDMs include include generators generators,, step-up step-up and station station service service transform transform-ers, generator bus and breakers, station service switchgear, powe powerr plan plantt ener energy gy mana manage geme ment nt syst system emss (SCA (SCADA) DA),, 480-V 480-V statio station n servic servicee and distri distribut bution ion system systems, s, statio station n batter battery y system systems, s, and statio station n lighti lighting ng and distri distribut bution ion systems.
18-3. Engineering Engineering Document Documentation ation The engineeri engineering ng documenta documentation tion in FDMs should should include include the methods, formulas, detailed computations, and results (if result resultss are obtain obtained ed from from engine engineeri ering ng softwa software re proprograms) grams) used to determine determine equipment equipment and system ratings and technica technicall design design paramete parameters. rs. Design Design alterna alternativ tives es invest investiga igated ted during during the equipm equipment ent or system system select selection ion process should be discussed together with the rationale for choosi choosing ng the selected selected alternat alternative ive.. FDMs FDMs should should contain contain suffic sufficien ientt detail detail not only only to facil facilita itate te the checki checking ng and revi review ew proc proces ess, s, but but to allo allow w prep prepar arat atio ion n of plan planss and and specifications accurately conveying the design intent.
d. Generator-vol Generator-voltage tage system system. A plan plan of the arra arrang ngeement ment of the genera generator tor bus and breake breakerr system system,, togeth together er with locating and limiting dimensions, equipment ratings, generator surge protection equipment, and excitation system power potential system taps, should be provided with the FDM. In addition, addition, a plant one-line one-line diagram diagram should be provided. e. Station Station service service system systemss.
Drawin Drawings gs with with arran arrangegements, ments, locati locations ons,, limiti limiting ng dimens dimension ionss and one-li one-line ne diadiagram gramss for for medi medium um-v -vol olta tage ge swit switch chge gear ar,, lowlow-vo volt ltag agee switchgear switchgear,, and low-voltage low-voltage motor control control centers centers of the station service system should be included with the FDM. f. Control system. Drawin Drawings gs includ included ed with with the con-
trol trol system system FDM should should define define the design design of the plant energy energy managemen managementt (SCADA) (SCADA) system, system, the plant plant control control and relay scheme, the control and protective relay switchboar boards ds,, and and asso associ ciat ated ed equi equipm pmen ent. t. The The plan planss shou should ld provide provide sufficient sufficient information information regarding regarding control control and protective tective relay functions functions to convey convey the intended intended operation operationss of the plant’ plant’ss contro controll and protec protectiv tivee relayi relaying ng system systems. s. Typically Typically,, unit one-line diagrams, diagrams, unit and plant control and protective relaying schematics, station service control and protective relaying schematics, and block diagrams of the plant’s energy management system adequately provide this informa information. tion. In addition, addition, a control room room layout, and
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EM 1110-2-3006 30 Jun 94 a layout layout with control equipment equipment locations, locations, together together with loca locati ting ng and and limi limiti ting ng (if (if nece necess ssar ary) y) dime dimens nsio ions ns,, is provided. g. Communication Communicationss systems systems. A drawin drawing g of the exte extent nt
and composition of leased commercial telephone facilities, the code call system, and dedicated communications systems tems for utilit utility y commun communica icatio tions, ns, teleme telemetry try,, and plant plant energy energy manage managemen mentt system systemss (SCADA (SCADA)) should should be proprovided. vided. Drawin Drawings gs with with locati locations ons of the commerc commercial ial teletelephone phone main main distri distribut bution ion frame, frame, code code call call statio stations, ns, and dedicated communication system components of either the power line carrier, carrier, microwave microwave system, system, or the fiber-optic fiber-optic system should be provided. h. Direct Direct current current system system. In additi addition on to the one-l one-line ine and schematic schematicss described described in paragraph paragraph 18-4 f , a prelim prelimii-
nary layout should be provided of the DC system equipment. ment. The drawing drawing should should include include the rating rating of batter battery y chargers, inverters, and batteries; any limiting dimensions of equipment; and the arrangement of the battery cells. i. Lighting Lighting and recepta receptacle cle systems systems.
Draw Drawin ings gs of of the the plant normal and emergency emergency lighting lighting systems systems should be
18-2
provided. provided. Informati Information on regarding regarding connected connected lighting system loads, intended feeder sizes, and location of lighting distributi distribution on panels panels and transform transformers ers should should be included. included. In addition, addition, informati information on on intended intended lighting lighting intensitie intensitiess throug throughou houtt the plant plant and propos proposed ed types types of lumina luminaire iress should be provided. j. Grounding systems.
A plan lan of the powe powerr plan lant ground mat, including taps to major equipment, should be provided. provided. A similar plan plan should be provided provided if a separate separate swit switch chya yard rd grou ground nd mat mat is incl includ uded ed in the the proj projec ectt development. k. Condui Conduitt and cable cable tray tray system systemss.
Desi Design gn lay layou outs ts with with locati locations ons and prefer preferred red method methodss of routin routing g major major cond condui uitt runs runs (inc (inclu ludi ding ng numb number er and and size size of cond condui uit) t) should should be provid provided. ed. Simila Similarr layout layoutss should should be provid provided ed for for the the plan plant’ t’ss cabl cablee tray tray syst system ems. s. Thes Thesee prel prelim imin inar ary y layo layout utss form form the the basi basiss for for deta detail iled ed draw drawin ings gs of thes thesee syst system emss prep prepar ared ed for for the the powe powerh rhou ouse se cons constr truc ucti tion on contract. l. Wire Wire and cable cable. Design Design drawings drawings are not prepared prepared
for this phase of the work.
EM 1110-2-3006 30 Jun 94
Chapter 19 Construction Specifications and Drawings
19-1. Specificatio Specifications ns
practi practices ces becaus becausee the specif specifica icatio tions ns and plans plans must must be self-explanatory without amplification about details of the constructi construction on or equipment equipment fabricatio fabrication. n. Typically Typically,, private private sector sector specif specifica icatio tions ns depend depend on interp interpret retati ations ons of the engine engineeri ering ng organi organizat zation ion design designing ing the projec project. t. Privat Privatee sector sector specif specifica icatio tions ns are unsuit unsuited ed to the Corps Corps of EngiEngineers’ neers’ compet competiti itive ve open open biddin bidding g method methodss of awardi awarding ng contracts and performing the work.
a. Types Types of contra contracts cts. Construct Construction ion specificat specifications ions and
drawings for hydroelectric power plant work are used for two different different classes classes of contracts: contracts: supply supply contracts contracts for the purchase of built-to-order equipment from manufacturers; and construction contracts for the building of the powerhouse, switchyard, and related structures. When construction begins before engineering engineering and design design of all features are completed completed,, secondsecond- and third-stag third-stagee constructi construction on contracts tracts are used used to cover cover the supers superstru tructu cture re and/or and/or wiring wiring and installation of machinery and equipment. b. Select Selection ion of contra contract ct type. The The choic choicee of wheth whether er to includ includee electr electrica icall equipm equipment ent procur procureme ement nt within within the powe powerh rhou ouse se cons constr truc ucti tion on scop scopee of resp respon onsi sibi bili lity ty,, to directly directly purchase purchase the required required equipment equipment for installati installation on by the contractor (installation only), or to procure design, fabricatio fabrication, n, and installa installation tion of equipment equipment (“turn-ke (“turn-key”) y”) is depe depend nden entt upon upon a numb number er of fact factor ors. s. Thes Thesee fact factor orss include equipment procurement lead times, the complexity of the fabricated equipment, and the need for specialized installat installation ion skills. skills. Generally Generally,, supply supply contracts contracts are used to procure equipment with long lead times, equipment with a high high degr degree ee of comp comple lexi xity ty,, or equi equipm pmen entt requ requir irin ing g specia specializ lized ed instal installat lation ion skills skills and techni technique ques. s. Typica Typicall equipment procured with supply contracts includes generators ators (turn(turn-key key procur procureme ement) nt),, SCADA SCADA system systems, s, highhighvoltage bus and breakers, generation step-up transformers, and generator generator-- and high-volta high-voltage ge power circuit breakers. breakers. Low-voltage Low-voltage switchgear switchgear,, motor control centers, centers, lighting lighting panels panels,, and cable cable tray tray system systemss are typica typicall of equipm equipment ent included in a construction scope of supply. c. Specifi Specificat cation ion prepar preparati ation on. Gene Generral cri criteri teriaa and and polici policies es to be observ observed ed in prepar preparing ing specif specifica icatio tions ns are found found in Append Appendix ix A of Guide Guide Specif Specifica icatio tion n CE-400 CE-4000. 0. Specifica Specifications tions and plans should be carefully carefully coordinated, coordinated, and various various sections sections in a given specificati specification on (sometim (sometimes es prepared prepared by different different writers) writers) checked checked to ensure ensure consisconsistency, eliminate conflicts, clearly define limits of payment item items, s, and and avoi avoid d over overla lapp ppin ing g paym paymen ents ts for for any any item item.. Specifications are prepared to accommodate three classes of users users of the specifi specificat cation ions: s: the constru constructi ction on and/or and/or manufactur manufacturing ing contractor contractor,, the resident resident engineer, engineer, and the field field or shop inspector inspector.. Specificat Specifications ions for Corps of Engineer neerss civi civill work workss proj projec ects ts diff differ er from from priv privat atee sect sector or
19-2. Construction Construction Drawings Drawings a. Genera Generall. Constr Construct uction ion drawin drawings gs should should be comcomplete and based on commercially available equipment and indust industryry-rec recogn ognize ized d constr construct uction ion and instal installat lation ion techtechniqu niques es.. Deta Detail ilss of equi equipm pmen entt desi design gn and and inst instal alla lati tion on,, wiring wiring,, and condui conduitt should should be comple complete te to minimi minimize ze the need need for for fiel field d revi revisi sion on.. Disc Discus ussi sion onss in the the foll follow owin ing g paragraphs indicate the type and scope of information that should be included on construction drawings for the various phases of work covered by this chapter. b. Genera Generator torss.
(1) Select Selected ed or modifi modified ed drawin drawings gs from from the general general arrang arrangeme ement nt drawin drawings gs of the powerh powerhous ousee are genera generally lly used used to acco accomp mpan any y the the spec specif ific icat atio ions ns for for purc purcha hase se of generators generators.. Drawings Drawings prepared prepared to accompany accompany guide specifications should indicate various mechanical and electrical interfaces including main leads, piping terminations (e.g., lube oil, cooling water, CO 2, brake air), neutral equipment locations, and excitation system equipment locations. (2) (2) A plan plantt or main main unit unit oneone-li line ne diag diagra ram m shou should ld also also be includ included ed in the procur procureme ement nt drawin drawing g set. set. EquipEquipment ment center centerlin linee should should be dimens dimension ioned ed from from struct structure ure lines. lines. Powerhouse Powerhouse crane crane hook coverage should should be shown on the appropri appropriate ate procure procuremen mentt drawin drawing g set. set. Other Other govgoverni erning ng or limi limiti ting ng dime dimens nsio ions ns shou should ld be esta establ blis ishe hed. d. Locations and dimensions of openings, sleeves, and interfering fering equipm equipment ent should should be shown shown where possibl possible. e. In cases where dimensions cannot be determined until later, the dimensio dimension n lines lines should should be drawn drawn in and indica indicatio tion n made made that that the the dime dimens nsio ion n will will be adde added d at a late laterr date date.. Generator Generator procurement procurement drawings may be included included in the constructi construction on contract contract set to show the extent of generator generator erection performed by the generator supplier. c. Transformer Transformerss.
(1) (1) Suit Suitab able le draw drawin ings gs show showin ing g the the loca locati tion on and and general general arrangeme arrangement nt of the transform transformers ers and connecting connecting bus bus stru struct ctur ures es and and limi limits ts of work work unde underr the the cont contra ract ct
19-1
EM 1110-2-3006 30 Jun 94 should should be includ included ed with with the transf transform ormer er procur procureme ement nt specifications. (2) (2) The The draw drawin ings gs shou should ld incl includ udee all all feat featur ures es not not adequa adequatel tely y covere covered d in the specif specifica icatio tions ns affect affecting ing the design design of the transformers transformers or powerhouse powerhouse,, such as limitlimiting transformer dimensions, rails and other provisions for lifting and moving the transformers, locations of terminal cabi cabine nets ts,, surg surgee arre arrest ster ers, s, chil chilli ling ng sump sumpss and and wall wallss between between transform transformers, ers, bushing bushing enclosure enclosuress for connection connection to metalmetal-enc enclos losed ed bus, bus, and locati location on of heat heat exchan exchanger gers. s. Othe Otherr deta detail ilss incl includ udee size size of oil oil pipe pipess for for Clas Classs FOW FOW transform transformers ers where the heat exchangers exchangers will be installe installed d remotely from the transformers, types and sizes of bushing terminal connectors, and provisions for grounding the neutrals of the high-voltage windings and the transformer tanks. d. High-v High-volta oltage ge system system.
Cons Constr truc ucti tion on drawi drawing ngss for for this system should show all necessary layouts and details for installation of equipment from the high-voltage bushings of the transformers to the outgoing transmission line interf interface ace in the switchy switchyard ard.. These These plans plans should should include include drawings of the high-voltage leads with details of termination points; points; switchyard switchyard equipment equipment arrangeme arrangement nt drawings, drawings, including plans, sections, elevations, and details; structure load loadin ing g diag diagra rams ms;; cond condui uitt and and grou ground ndin ing g plan plans; s; and and detail detailss of lighti lighting ng and power power panels panels and other other miscel miscellalaneous equipmen equipment. t. A one-line diagram diagram of the high-voltage high-voltage system should be prepared, together with control schematics of controlled controlled equipment equipment.. Manufactur Manufacturers’ ers’ shop drawdrawings are used to a great extent in the actual installation of equipment.
one-li one-line ne diagra diagram m and drawin drawings gs used used for purcha purchase se of the switch switchgea gearr and motor motor contro controll center centers, s, if supply supply of this this equipm equipment ent is not includ included ed in the constr construct uction ion scope scope of supply. (2) Station Station service service switchgear. switchgear. (a) The statio station n servic servicee switch switchgea gearr drawin drawings gs should should show all information necessary for design of the switchgear and, insofar as possible, the information needed for installation. (b) (b) The The swit switch chge gear ar draw drawin ings gs shou should ld indi indica cate te the the frame size and ampere rating of each breaker, as well as the namepla nameplate te designat designation ion of each each circui circuit. t. Wire Wire sizes sizes of outgoing feeders should be provided for correct sizing of circui circuitt breake breakerr lugs. lugs. The number number and rating rating of curren currentt and potential potential transformer transformerss should should be indicated indicated.. The preferred ferred layout layout of indicating indicating and control control equipment equipment should be shown. (c) (c) A oneone-li line ne diag diagra ram m shou should ld be prep prepar ared ed of the the switchgear switchgear line-up. line-up. Centerlin Centerlinee dimensions dimensions and preferred preferred routin routing g of any bus includ included ed in the switchge switchgear ar scope scope of supply supply should should be provided. provided. (d) Drawin Drawings gs showin showing g the switch switchgea gearr instal installat lation ion should be prepared with sufficient arrangement flexibility to accommodat accommodatee variation variationss in dimensions dimensions among equipequipment ment suppli suppliers ers.. Drawin Drawings gs prepared prepared for the purcha purchase se of the switchgear are also included in the contract construction tion drawin drawings gs to indica indicate te the scope scope and comple complexit xity y of instal installat lation ion and connec connectio tion. n. Manufa Manufactu cturer rers’ s’ shop shop drawdrawings are used for installation of the switchgear.
e. Generator-vol Generator-voltage tage system system. Drawin Drawings gs for the the genergener-
ator-v ator-volt oltage age system system should should show show suffic sufficien ientt detail detailss for purc purcha hase se of the the gene genera rato torr main main and and neut neutra rall lead leadss and and associ associate ated d equipm equipment ent,, and the genera generator tor switch switchgea gearr if included included in the supply supply scope. The drawings drawings should should show the general layout, details of arrangemen arrangementt and ratings of equipment, limiting dimensions, termination methods, and a one-li one-line ne diagram diagram showing showing items of equipmen equipment. t. If the supply scope includes generator switchgear, control schematics matics of the contro controlle lled d equipm equipment ent should should be provid provided. ed. These These drawin drawings gs are also also includ included ed with with the drawin drawings gs for the construction contract to show the extent of the installation lation work. Manufactur Manufacturers’ ers’ detail detail drawings drawings are used for installation of this equipment. f. Station service systems.
(1) Genera General. l. Constr Construct uction ion drawing drawingss for the station station serv servic icee syst system em shou should ld cons consis istt of the the stat statio ion n serv servic icee
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(3) Motor contr control ol centers. centers. (a) Drawings Drawings for motor control control centers are similar similar in scope scope to the drawin drawings gs of the switchg switchgear ear.. Motor Motor control control centers consist of free-standing cubicles containing combinations nations of standardiz standardized ed factory factory subassembl subassemblies. ies. The stanstandardized units described in Chapter 7 are preferred. (b) Outsid Outsidee dimens dimension ionss of embedd embedded ed cabine cabinets ts and locations of conduits for supply and branch circuits should be shown. Motor Motor control control center center elevat elevation ionss indica indicatin ting g preferred location of starters, control switches, and nameplat plates es should should be show shown. n. A oneone-li line ne diag diagra ram m with with the the relative positions of equipment enclosed within the control center, direction of bus runs, the location of bus lugs, and the ratings of all equipment should be provided.
EM 1110-2-3006 30 Jun 94 (c) The drawin drawings gs should should contai contain n tabula tabulatio tions ns of the circuit circuit number, number, the nameplate nameplate designation designation of the circuit, circuit, the expected load, the breaker frame size, the starter size, and the number and size of conductors. (4) Lighting Lighting and power panelboar panelboards. ds. (a) (a) The The purc purcha hase se and and inst instal alla lati tion on of ligh lighti ting ng and and power panels are included in the powerhouse construction contra contract. ct. Drawin Drawings gs are prepar prepared ed showin showing g the size size of the embedded cabinets, the size of the front covers, bus diagrams, grams, and any pertinent pertinent details such as space allocatio allocation n and wiring wiring diagra diagrams ms for throwthrow-ove overr switch switches es or remote remote contro controll switch switches es located located in the panels. panels. Tabula Tabulatio tions ns of main main bus curren currentt rating ratings, s, main main breake breakerr rating ratings, s, locati location on and sizes of main and neutral lugs, and the number and ratings ratings of branch-cir branch-circuit cuit breakers breakers should should be included included on the drawings. (b) Lighting Lighting plan circuit designation designationss should be provided vided on the panel panel bus diagram diagrams. s. Panel Panel layouts layouts should should provide space for spare and future circuit breakers. (c) Doors, locks, locks, and details of door openings openings should be show shown. n. Fron Frontt cove covers rs shou should ld over overla lap p the the embe embedd dded ed cabine cabinett approx approxima imatel tely y 1 in. all around around.. All contac contactor torss should should be comple completel tely y separa separated ted by barrie barriers rs from from other other equipment equipment and from wire gutters. gutters. (d) Buses should should also be completel completely y enclosed except except at the ends of runs runs.. The The nece necess ssit ity y for for the the remo remova vabl blee cover over the bus lugs should be considered in locating equipment within the cabinet. g. Contro Controll system system.
Drawin Drawings gs issued issued for purch purchase ase of switchboar switchboards, ds, control control panels, panels, and the operator’s operator’s control console (if required), comprising the plant control system, should include plant and unit one-line diagrams, plant and unit control and protective protective relay schematic schematics, s, station station service control and protective protective relay schematic schematics, s, and associassociated ated equi equipm pmen ent. t. Othe Otherr draw drawin ings gs that that shou should ld be in the the drawing package include switchboard and control console arra arrang ngem emen ents ts show showin ing g pref prefer erre red d loca locati tion onss of rela relays ys,, instrument instruments, s, and control control switches. switches. Preparati Preparation on of wiring wiring diagra diagrams ms for this this equipm equipment ent should should be includ included ed in the manufacturer’s scope of supply, together with the preparation tion of termin terminal al connec connectio tion n diagra diagrams ms to which which extern external al plant interconnection details can be added during the shop drawin drawing g review review process process.. If a plant plant energy energy manage managemen mentt system system (SCADA) (SCADA) is incorp incorpora orated ted in the contro controll system system procur procureme ement, nt, block block diagra diagrams ms of the system system should should be incorpora incorporated ted with the procurement procurement drawing drawing set. Control Control system drawings are also incorporated in the construction
drawing set for information as to the extent of the installation lation work. work. Actual Actual instal installat lation ion of the control control system system should should be perfor performed med in accord accordanc ancee with with the manufa manufaccturer’s turer’s approved approved drawings. drawings. Included Included in the constructio construction n set should be drawings providing locating dimensions for control system equipment. h. Annunciation Annunciation system system. Generally Generally,, annunciato annunciators rs are
includ included ed in the scope of supply supply for the control control switch switch-boar boards ds.. A draw drawin ing g of the the inco incomi ming ng trou troubl blee and and alar alarm m points to the annunciators, together with preferred window arrang arrangeme ements nts and window window legend legends, s, should should be provid provided. ed. Incomi Incoming ng troubl trouble, e, alarm, alarm, and event event points points to the plant plant sequen sequencece-ofof-eve event nt record recorder er (SER), (SER), togeth together er with with a prepreferred ferred format format for printo printout ut of record recorded ed events events,, should should be provided on the drawings. i. Communication Communicationss system system. Drawin Drawings gs that defin definee the
scope of facilities that will permit the installation of communicatio munication n terminat termination ion equipment equipment should should be included included in the constructio construction n drawing set. The constructio construction n contractor contractor will provide provide the facilities facilities.. The communicat communication ion terminatermination equipment equipment will be furnished and installed installed by others others (see Chapter Chapter 10). In addition, addition, a drawing with locations locations of the plant’s code call system should be prepared. j. Direct current system.
The The drawi drawing ng for for the purpurchase chase of the battery battery switch switchboa board rd is simila similarr in scope scope to those those for the equipm equipment ent discus discussed sed in paragr paragraph aph 19-2 19-2 g. The battery battery switchboard switchboard is generally generally purchased purchased with the control control switchboard. switchboard. The battery battery switchboard switchboard drawing is included with the construction contract drawings to depict the extent of the work and provide explanatory material. k. Lighting Lighting and receptacle receptacle systems systems.
(1) (1) Ligh Lighti ting ng draw drawin ings gs on the the ligh lighti ting ng plan plan for for an area should show all fixture, fixture, switch, switch, and receptacle receptacle outlets, and all conduits in the walls and ceiling. (2) Condui Conduits ts in the ceiling ceiling and walls of an area area are shown shown on a floor floor plan of that area. area. Condui Conduitt in the floor floor slab for the same area, even though used to feed outlets in the area, should be shown on another plan as in the ceiling for the area below. (3) Buildi Building ng and room room outlin outlines, es, beams, beams, and openopenings ings,, shou should ld be show shown. n. Room Roomss shou should ld be iden identi tifi fied ed.. Normally, it is not necessary to show equipment on lighting ing draw drawin ings gs.. Sect Sectio ions ns and and deta detail ilss shou should ld be shown shown where where necess necessary ary for clarif clarifica icatio tion. n. Wiring Wiring diagra diagrams ms and equi equipm pmen entt shou should ld be deta detail iled ed in acco accord rdan ance ce with with the the drawing drawing legend. legend. All outlets, outlets, junction junction boxes, and conduit conduit
19-3
EM 1110-2-3006 30 Jun 94 term termin inat atio ions ns shou should ld be loca locate ted d by dime dimens nsio ions ns and, and, if necessary, by elevations. (4) The conduit system system should be detailed completel completely y and all sizes and material materialss noted. noted. Embedd Embedded ed conduit conduit for branch circuits should be limited to ¾- and 1-in. sizes if possible. possible. Conduits Conduits serving serving ceiling fixtures fixtures in areas with with suspended ceilings should be stubbed out of the concrete. The The cond condui uitt will will be exte extend nded ed to fixt fixtur uree outl outlet et boxe boxess before placing the ceiling suspension system. (5) (5) Boxe Boxes, s, exte extens nsio ion n ring rings, s, and and cove covers rs shou should ld be suited to the finish of the space in which they are used with with approp appropria riate te notati notations ons or detail detailss made made on the drawdrawings to ensure the use of the proper materials and fittings. Wall outlet boxes should be sheet metal boxes with suitable able extens extension ion rings rings when when locate located d above above the genera generator tor room floor. floor. On turbine turbine room walls, boxes boxes should be cast boxes meeting the requirements of UL 514A. (6) Complete Complete details details should be given for lighting lighting fixture mountings, wiring devices, and device plates. Circuits should be designated by lighting panel number and circuit number and balanced across the lighting panel buses and transform transformer. er. The number and sizes sizes of wires in each conduit are indicated indicated by standard standard hash marks marks and notes. The syst system em shou should ld be colo colorr-co code ded d as note noted d on the the typi typica call drawing. (7) To avoid confusion, confusion, local switches switches and their controlled trolled fixtures should have an individual individual letter designation tion to indi indica cate te thei theirr rela relati tion on.. Fixt Fixtur ure, e, swit switch ch,, and and receptacle types should be designated on the drawings and referred to a schedule giving the fixture type by reference to a catalo catalog g produc productt or to a detail detail drawin drawing. g. The schedul schedulee should also show all mounting fittings. Grou Ground ndin ing g syst system em drawi drawing ngss should should include include all plans, plans, informati information, on, and details details necesnecessary sary for the instal installat lation ion of the power power plant plant ground ground mat, mat, the main main powerh powerhous ousee ground grounding ing networ network, k, and taps taps and conn connec ecti tion onss to equi equipm pmen ent. t. The The taps taps from from the the main main ground network to equipment may be shown conveniently on the power power and contro controll condui conduitt plans. plans. Detail Detailss should should include test stations if used, water seals, exposed ground bus bus supp suppor orts ts,, and and typi typica call conn connec ecti tion onss to the the fram framee or housing of plant equipment and metal structures.
design designate ated d area. area. Obstru Obstructi ctions ons,, struct structura urall featur features, es, and locations of equipment influencing conduit location should be shown on the drawings. (2) Condui Conduits ts should should be in accord accordanc ancee with with the legend. end. Each Each condui conduitt shou should ld be labe labele led d with with the size size and and conduit number shown in the conduit and cable schedule. Conduit Conduit terminat termination ion locations locations should be dimension dimensioned ed to building control lines wherever possible. (3) All outlet outlet boxes boxes and cabinet cabinetss should should be shown shown on the drawin drawings gs with with size, size, locati location, on, and, and, if applic applicabl able, e, design designati ation on number numberss given. given. Any requir required ed boxes boxes should should be located and detailed. (4) Where Where a number number of conduit conduitss stub out of a wall or floor floor within within a small small area, area, a struct structura urall steel steel termin terminal al plate plate should should be detail detailed ed for use in holdin holding g the conduits conduits rigidly rigidly in place during concrete concrete placement placement operations. operations. If condui conduitt locati locations ons are not known when when the drawin drawings gs are prepared, indication should be made that dimensions will be furnished at a later date. (5) (5) Suff Suffic icie ient nt elev elevat atio ions ns and and deta detail ilss of cond condui uits ts entering junction boxes, pull boxes, or cabinets should be prov provid ided ed show showin ing g the the comp comple lexi xity ty of the the work work and and the the quality and size of allowable electrical construction materials. rials. Where Where stubs are left in concrete concrete walls walls or ceilin ceilings gs for for expo expose sed d runs runs to equi equipm pmen ent, t, the the cond condui uitt shou should ld be stubbed flush with a coupling and closed with a pipe plug. (6) (6) One One or two two spar sparee cond condui uits ts shou should ld be run run from from each motor control center or lighting lighting panel wall location location to 6 in. below the ceiling of the room in which the installation lation is located and terminat terminated ed in a flush coupling. coupling. One or more spare conduits should be similarly terminated in the room below the installation.
l. Ground Grounding ing system systemss.
m. Condui Conduitt and cable cable tray systems systems.
(1) Conduit Conduit plans for station station service service power and for all contro controll circui circuits, ts, includ including ing the commun communica icatio tion n system system,, shou should ld show show the the cond condui uits ts in the the floo floorr and and wall wallss of the the
19-4
(7) Pull boxes, boxes, embedded embedded power cabinets, cabinets, and junction tion boxes boxes should should be comple completel tely y detail detailed ed to show show size, size, material, material, flange flange width, width, front covers, and conduit conduit drilling. drilling. For For cast cast iron iron boxe boxes, s, a stan standa dard rd cata catalo log g prod produc uctt with with drilled and tapped conduit entrances is specified. (8) (8) Draw Drawin ings gs shou should ld show show the the arra arrang ngem emen entt and and loca locati tion on of the the comp comple lete te tray tray syst system em.. Deta Detail ilss of tray tray hangers, hangers, supports supports and splices, and supporting supporting blocks for cables entering or leaving the trays, should be shown on the drawings. drawings. The trays should should be suitably suitably identified identified for listing listing in cable cable schedule reference references. s. Constructi Construction on details of all fabric fabricate ated d compon component entss should should be provid provided ed on the drawin drawing. g. Compon Component ent totals totals should should be included included on a bill bill of materials.
EM 1110-2-3006 30 Jun 94 n. Wire Wire and and cabl cablee.
The cable cable and and conduit conduit sched schedule ule should be prepared as outlined in Chapter 15. It is convenient to list the multiconductor control cables separately from power cables. ComputerComputer-gener generated ated spreadsheet spreadsheetss are generally used for listing all power plant power, control, and communi communicat cation ionss cables cables.. The locatio locations ns of wire wire and cable cable in trays trays should should be shown shown on tray tray diagra diagrams. ms. These These diagrams will expedite construction and provide “as construct structed” ed” engine engineeri ering ng docume documenta ntatio tion n useful useful for plant plant maintenance.
19-5
EM 1110-2-3006 30 Jun 94
Chapter 20 Analysis of Design
20-1. Permanent Permanent Record The The “Ana “Analy lysi siss of Desi Design gn”” memo memora rand ndum um shou should ld be a permanent permanent record record for future future reference. reference. It should consoliconsolidate date into into one one docu docume ment nt engi engine neer erin ing g info inform rmat atio ion n and and computations from previously approved design memorandums pertinent pertinent to the executed executed plans and specifica specifications tions..
20-2. Up-To-Date Up-To-Date Values Orig Origin inal al comp comput utat atio ions ns base based d on assu assume med d valu values es for for machine or equipment characteristics are revised to reflect up-t up-too-da date te valu values es base based d eith either er on the the manu manufa fact ctur urer ers’ s’ design calculations or on field or factory test measurements.
20-3. Expansion Expansion If provis provision ionss are made made in the powerh powerhous ousee or switch switchyar yard d design design for future addition of units, units, transmiss transmission ion lines, or auxiliary equipment, the Analysis of Design memorandum should detail the provisions for the expansion.
20-1
EM 1110-2-3006 30 Jun 94
Appendix A References
ANSI C2-1993 National Electrical Safety Code
A-1. A-1.
ANSI C37.06-1987 Americ American an Nation National al Standa Standard rd for Switch Switchgea gearr - AC HighHighVoltage Circuit Breakers Rated on a Symmetrical Current Bas Basis - Pre Preferr ferreed Rati Rating ngss and and Rel Relate ated Requ Requiired red Capabilities
Requir Required ed Publica Publicatio tions ns
TM 5-810-1 Mechanical Design, HVAC ER 1105-2-100 Guidance for Conducting Civil Works Planning Studies ER 1110-2-103 Stro Strong ng Moti Motion on Inst Instru rume ment nt for for Reco Record rdin ing g Eart Earthq hqua uake ke Motions on Dams EM 1110-2-3001 Plan Planni ning ng and and Desi Design gn of Hydr Hydroe oele lect ctri ricc Powe Powerr Plan Plantt Structures EM 1110-2-4205 Hydroelectric Power Plant Mechanical Design CE 4000 Civil Works Guide Specification for Lump Sum Contract for Engine Engineeri ering ng Servic Services es for Design Design of Hydroe Hydroelec lectri tricc Power Plant CW-13331 Civil Works Guide Specificat Specification ion for Supervisor Supervisory y Control Control and Data Acquisition Equipment
ANSI C37.16-1980 American American National National Standard Standard Preferred Preferred Ratings, Ratings, Related Related Requir Requireme ements nts,, and Applic Applicati ation on Recomm Recommend endati ations ons for LowLow-Vo Volt ltag agee Powe Powerr Circ Circui uitt Brea Breake kers rs and and AC Powe Powerr Circuit Protectors ANSI C37.90.1-1989 IEEE IEEE Standa Standard rd Surge Surge Withst Withstand and Capabi Capabilit lity y (SWC) (SWC) Test Test for Protective Relays and Relay Systems (ANSI) ANSI C80.1-1983 Rigid Steel Conduit-Zinc Coated ANSI C84.1-1989 American American National National Standard Standard Voltage Voltage Ratings Ratings for Electric Electric Power Systems and Equipment (60 Hz) ANSI/IEEE 242-1986 IEEE Recommended Recommended Practice Practice for Protection Protection and CoordiCoordination of Industrial and Commercial Power Systems ANSI/ISA S18.1-1981 Annunciator Sequence and Specifications
CW-16120 Civil Works Guide Specificati Specification on for Insulated Insulated Wire and Cable
EPRI EL-5036 Power Plant Electrical Electrical Reference Reference Series, Series, Vol. 2, “Power Transformers”
CW-16211 Civi Civill Works orks Gui Guide Spec Specif ific icaation tion for for Rewi Rewind nd of Hydraulic-Turbine-Driven Alternating Current Generators
EPRI EL-5036 Power Power Plant Plant Electr Electrica icall Refere Reference nce Series Series,, Vol. Vol. 4, “Wire “Wire and Cable” Cable”
CW-16252 Civi Civill Wo Work rkss Guid Guidee Spec Specif ific icat atio ion n for for Gove Govern rnor orss for for Hydraulic Turbines and Pump Turbines
EPRI EL-5036 Power Plant Electrical Reference Series, Vol. 5, “Grounding and Lightning Protection”
CW-16320 Civil Works Guide Specification for Power Transformers
EPRI EL-5036 Powe Powerr Pla Plant Elec Electtrica ricall “DC Distribution”
AIEE Transactions on Power Apparatus and Systems, 1953 (Oct) Charac Character terist istics ics of SplitSplit-Pha Phase se Curren Currents ts as a Source Source of Generator Protection, Paper 53-314.
Refe Refere renc ncee
Seri Series es,,
Vol. Vol.
9,
A-1
EM 1110-2-3006 30 Jun 94 EPRI EL-5036 Power Plant Electrical Reference Series, Vol. 10, “Electrical and Instrumentation” EPRI EL-5036 Powe Powerr Plan Plantt Elec Electr tric ical al “Communications”
Refe Refere renc ncee
Seri Series es,,
Vol. Vol. 13, 13,
EPRI TR-101710, 1993 EPRI Lighting Fundamentals Handbook IEEE Transactions on Power Apparatus and Systems, 1983 IEEE IEEE Transa Transacti ctions ons on Power Power Appara Apparatus tus and System Systems, s, 1983, Vol PAS-102, No. 9 (September). IEEE Transactions on Power Apparatus and Systems, 1983 IEEE IEEE Transa Transacti ctions ons on Power Power Appara Apparatus tus and System Systems, s, 1983, Vol PAS-102, No. 10 (October).
IEEE 484-1987 IEEE Recommende Recommended d Practice Practice for Installa Installation tion Design Design and Installat Installation ion of Large Lead Storage Storage Batteries Batteries for GeneratGenerating Stations and Substations (ANSI) IEEE 485-1983 IEEE IEEE Recomm Recommend ended ed Practi Practice ce for Sizing Sizing of Large Large Lead Lead Storage Batteries for Generating Stations and Substations (ANSI) IEEE 605-1987 IEEE IEEE Guid Guidee for for Structures (ANSI)
Desi Design gn
of
Sub Substa station tion
Rigi Rigidd-Bu Buss
IEEE 946-1992 IEEE Recommended Practice for the Design of DC Auxiliary Power Systems for Generating Stations IEEE 979-1984 (Reaffirmed 1988) IEEE Guide for Substation Fire Protection (ANSI)
IEEE 43-1974 IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery (ANSI)
IEEE 980-1987 IEEE Guide for Containment and Control of Oil Spills in Substations (ANSI)
IEEE 80-1986 IEEE IEEE Guid Guidee for for Safe Safety ty in AC Subs Substa tati tion on Grou Ground ndin ing g (ANSI)
IEEE 1010-1987 IEEE IEEE Guide Guide for Contro Controll of Hydroe Hydroelec lectri tricc Power Power Plants Plants (ANSI)
IEEE 81-1983 IEEE IEEE Guide Guide for Measur Measuring ing Earth Earth Resist Resistivi ivity, ty, Ground Ground Impeda Impedance nce,, and Earth Earth Surfac Surfacee Potent Potential ialss of a Ground Ground System
IEEE C37.013-1988 IEEE IEEE Standa Standard rd for AC High-V High-Volt oltage age Genera Generator tor Circui Circuitt Breakers Rated on a Symmetrical Current Basis (ANSI)
IEEE 115-1983 IEEE Test Procedures for Synchronous Machines (ANSI) IEEE 142-1991 IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems (ANSI) IEEE 399-1990 IEEE Recommended Practice for Power Systems Analysis IEEE 422-1986 IEEE Guide for Design and Installation of Cable Systems in Power Generating Generating Stations Stations (ANSI) IEEE 450-1987 IEEE Recommende Recommended d Practice Practice for Maintenan Maintenance, ce, Testing, Testing, and Replac Replaceme ement nt of Large Large Lead Lead Storag Storagee Batter Batteries ies for Generating Stations and Substations (ANSI)
A-2
IEEE C37.122 (with Supplement .122a)-1983 IEEE Standard for Gas Insulated Substations (ANSI) IEEE C37.123-1991 IEEE Guide to Specification for Gas-Insulated Substation Equipment (ANSI) IEEE C37.2 Electrical Power System Device Function Numbers IEEE C37.20.2-1987 IEEE Standard Standard for Metal-Cla Metal-Clad d and Station-T Station-Type ype Cubicle Cubicle Switchgear (ANSI) IEEE C37.23-1987 IEEE IEEE Standa Standard rd for MetalMetal-Enc Enclos losed ed Bus and Calcul Calculati ating ng Losses Losses in IsolatedIsolated-Phase Phase Bus (ANSI) (ANSI)
EM 1110-2-3006 30 Jun 94 IEEE C37.91-1985 (Reaffirmed 1990) IEEE IEEE Guide Guide for Protec Protectiv tivee Relay Relay Applic Applicati ations ons to Power Power Transformers (ANSI)
IEEE C57.104-1991 IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers
IEEE C37.95-1989 Guide for Protectiv Protectivee Relaying Relaying of Utility Utility Customer Customer Interconnections (ANSI)
IEEE C57.116-1989 IEEE Guide for Transformers Directly Connected to Generators (ANSI)
IEEE C37.96-1988 IEEE Guide for AC Motor Protection (ANSI)
IEEE C57.120-1991 IEEE IEEE Standa Standard rd Loss Loss Evalua Evaluatio tion n Guide Guide for Power Power TransTransformers and Reactors (ANSI)
IEEE C37.97-1979 (Reaffirmed 1990) IEEE IEEE Guide Guide for Protec Protectiv tivee Relay Relay Applic Applicati ations ons to Power Power Systems Buses (ANSI) IEEE C37.101-1985 (Reaffirmed 1990) IEEE Guide for Generator Ground Protection (ANSI) IEEE C37.102-1987 (Reaffirmed 1991) IEEE Guide for AC Generator Protection
IEEE C62.1-1989 IEEE IEEE Stan Standa dard rd for for Gapp Gapped ed Sili Silico conn-Ca Carb rbid idee Arresters for AC Power Circuits (ANSI)
Surg Surgee
IEEE C62.11-1987 IEEE IEEE Stan Standa dard rd for for Meta Metall-Ox Oxid idee Surg Surgee Arre Arrest ster erss for for AC Power Circuits (ANSI)
IEEE C37.106-1987 IEEE IEEE Guid Guidee for for Abno Abnorm rmal al Freq Freque uenc ncy y Prot Protec ecti tion on for for Power Generating Plants (ANSI)
IEEE C62.2-1987 IEEE IEEE Guid Guidee for for the the Appl Applic icat atio ion n of Gapp Gapped ed Sili Silico connCarbide Carbide Surge Arresters Arresters for Alternatin Alternating g Current Current Systems Systems (ANSI)
IEEE C57.12.00-1987 IEEE IEEE Stan Standa dard rd Gene Genera rall Requ Requir irem emen ents ts for for Liqu Liquid id-Immers Immersed ed Distri Distribut bution ion,, Power, Power, and Regula Regulatin ting g TransTransformers (ANSI)
IEEE C62.92.2-1989 IEEE Guide for Grounding in Electrical Electrical Utility Utility Systems, Systems, Part Part II - Ground Grounding ing of Synchr Synchrono onous us Genera Generator tor System Systemss (ANSI)
IEEE C57.12.11-1980 IEEE IEEE Guid Guidee for for Inst Instal alla lati tion on of OilOil-Im Imme mers rsed ed Tran Transsform former erss (10M (10MVA VA and and Larg Larger er,, 69 kV kV - 287 287 kV kV Rati Rating ng)) (ANSI)
IES-RP-24-1989 VDT Lighting
IEEE C57.12.14-1982 IEEE Trial Use Standard for Dielectric Test Requirement for Power Transformers for Operation at System Voltage from 115 kV through 230 kV IEEE C57.12.90-1987 IEEE Standard Standard Test Code for Liquid-Imm Liquid-Immersed ersed DistribuDistribution. Power, Power, and Regulating Regulating Transform Transformers; ers; and Guide for ShortShort-Cir Circui cuitt Testin Testing g of Distri Distribut bution ion and Power Power TransTransformers (ANSI)
NEMA PE 1-1983 Uninterruptible Power Systems NEMA PE 5-1985 Utility Type Battery Chargers NEMA PE 7-1985 Communication Type Battery Chargers NEMA WC 50-1976 Ampacities, Including Effect of Shield Losses for SingleConduc Conductor tor SolidSolid-Die Dielec lectri tricc Power Power Cable Cable 15 kV throug through h 69 kV
IEEE C57.19.01-1991 IEEE Standard Standard Performan Performance ce Characteri Characteristic sticss and DimenDimensions for Outdoor Outdoor Apparatus Apparatus Bushings Bushings (ANSI)
NEMA WC 51-1986 Ampacities of Cables in Open-Top Cable Trays
IEEE C57.98-1986 IEEE Guide for Transformer Impulse Tests (ANSI)
NFPA 70-1993 “National Electric Code,” Article 480
A-3
EM 1110-2-3006 30 Jun 94 NFPA 101-1991 Code Code for for Safe Safety ty to Life Life from from Fire Fire in Buil Buildi ding ngss and and Structures UL 50-1980 Cabinets and Boxes UL 489-1986 The The Stan Standa dard rd for for Mold Molded ed-C -Cas asee Circ Circui uitt Brea Breake kers rs and and Circuit-Breaker Enclosures UL 1072-1988 The Standard for Medium-Voltage Power Cables UL 1569-1985 The Standard for Metal-Clad Cables Dawes, C. A. Electrical Engineering, Engineering, Vol II, AlterDawes, Chester A., Electrical nating Currents, McGraw Hill Book Co., 1947. Fitzgerald and Kingsley, Jr. Fitzge Fitzgeral rald, d, A. E., and Kingsl Kingsley, ey, Charle Charless Jr., Jr., Electric Machinery, McGraw Hill, 1961. Kaufman Kaufman, J. E., ed. IES Lighting Handbook . New New Yor York: k: Illu Illumi mina nati ting ng Engi Engine neer erin ing g Soci Societ ety y (IES (IES); ); Refe Refere renc ncee Volume, 1984.
ANSI C37.12-1981 American National Standard Guide Specifications for AC High-V High-Volt oltage age Circui Circuitt Breake Breakers rs Rated Rated on a Symmet Symmetric rical al Current Basis and Total Current Basis ANSI C37.32-1979 American American National National Standard Standard Schedules Schedules of Preferred Preferred Ratings, Manufacturing Specifications and Application Guide for High-Voltage Air Switches, Bus Supports, and Switch Accessories ANSI C50.12-1982 Americ American an Nation National al Standa Standard rd Requir Requireme ements nts for Salien SalienttPole Synchronou Synchronouss Generators Generators and Generator/ Generator/Motor Motorss for Hydraulic Turbine Applications ANSI C84.1-1989 American National Standard Voltage Ratings for Electric Power Systems and Equipment (60 Hz) ANSI C93.1-1972 Requirements for Powerline Coupling Capacitors ANSI C93.2-1976 Requiremen Requirements ts for Powerline Powerline Coupling Coupling Capacitor Capacitor Voltage Voltage Transformers ANSI C93.3-1981 Requirements for Powerline Carrier Traps
Kent 1950 Kent, Willia William m 1950. “Mechanic “Mechanical al Engineers Engineers Handbo Handbook,” ok,” John Wiley and Sons, Inc.
ANSI/NFPA 851-1987 Recommended Practice for Fire Protection for Hydroelectric Generating Plants
Marks 1951 Mark Marks, s, Lione Lionell S. 1951 1951.. “The “The Mecha Mechani nica call Engine Engineer ers’ s’ Handbook,” McGraw-Hill Book Co., New York.
EPRI EL-5036 Power Plant Electrical Reference Series, Vols. 1, 2, 3, 5, 7, and 8.
Puchstein, Lloyd, and Conrad Puchstein, A. F., Lloyd, T. C., Conrad, A. G. Alternating Current Machines, John Wiley & Sons, 1954.
Electric Utility Engineering Reference Book Electric Utility Engineering Reference Book - Distribution Systems, Systems, Volume Volume 3, available available from: from:
A-2. A-2.
Related Rela ted Publica Publicatio tions ns
ER 1105-2-100 Guidance for Conducting Civil Works Planning Studies ETL 1110-3-376 Telephone System ANSI C2-1993 National Electric Safety Code
A-4
ABB Power T&D Services Co 1021 Main Campus Drive Raleigh, NC 27606 IEEE 1-1986 General General Principles Principles Upon Which Temperature Temperature Limits Limits are Base Based d in the the Rati Rating ng of Elec Electr tric ic Mach Machin ines es and and Othe Otherr Equipment
EM 1110-2-3006 30 Jun 94 IEEE 32-1972 IEEE Standard Requirements Requirements Terminolo Terminology gy and Test Procedures for Neutral Grounding Devices (ANSI)
IEEE 421.1-1986 IEEE IEEE Standa Standard rd Defini Definitio tions ns for Excita Excitatio tion n System Systemss for Synchronous Machines (ANSI)
IEEE 56-1977 IEEE IEEE Guid Guidee for for Insu Insula lati tion on Main Mainte tena nanc ncee of Larg Largee AC Rotating Machinery (10,000 kVA and larger) (ANSI)
IEEE 421.2-1990 IEEE Guide for Identification, Testing, and Evaluation of the Dynamic Dynamic Performanc Performancee of Excitation Excitation Control Systems Systems (ANSI)
IEEE 80-1986 IEEE IEEE Guid Guidee for for Safe Safety ty in AC Subs Substa tati tion on Grou Ground ndin ing g (ANSI) IEEE 94-1991 IEEE Recommended Definitions of Terms for Automatic Generation Control on Electric Power Systems IEEE 95-1977 IEEE IEEE Recomm Recommend ended ed Practi Practice ce for Insula Insulatio tion n Testin Testing g of Large AC Rotating Rotating Machinery Machinery with High Direct Direct Voltage Voltage (ANSI) IEEE 141-1986 IEEE Recommended Practice for Electric Power Distribution for Industria Industriall Plants Plants (ANSI) IEEE 242-1986 IEEE Recommende Recommended d Practice Practice for Protection Protection and CoordiCoordinati nation on of Indu Indust stri rial al and and Comm Commer erci cial al Powe Powerr Syst System emss (ANSI) IEEE 275-1981 IEEE Recommend Recommended ed Practice Practice for Thermal Thermal Evaluation Evaluation of Insulation Systems for AC Electric Machinery Employing Form-Wound Form-Wound Pre-Insul Pre-Insulated ated Stator Stator Coils, Coils, Machines Machines Rated 6900 V and Below (ANSI) IEEE 281-1984 IEEE IEEE Stan Standa dard rd Serv Servic icee Cond Condit itio ions ns for for Powe Powerr Syst System em Communication Equipment (ANSI) IEEE 286-1975 IEEE Recommended Recommended Practice Practice for Measurement Measurement of Power Factor Factor Tip-Up Tip-Up of Rotating Rotating Machinery Machinery Stator Stator Coil Insulation (ANSI) IEEE 367-1987 IEEE Recommended Practice for Determining the Electric Power Station Ground Potential Risk and Induced Voltage from a Power Fault (ANSI) IEEE 400-1991 IEEE IEEE Guide Guide for Making Making High-D High-Dire irectct-Vol Voltag tagee Tests Tests on Power Cable Systems in the Field (ANSI)
IEEE 421B-1979 IEEE Standard Standard for High-Poten High-Potential tial Test Requireme Requirements nts for Excitation Systems for Synchronous Machines (ANSI) IEEE 422-1986 IEEE Guide for Design and Installation of Cable Systems in Power Generating Generating Stations Stations (ANSI) IEEE 433-1974 IEEE IEEE Recomm Recommend ended ed Practi Practice ce for Insula Insulatio tion n Testin Testing g of Large AC Rotating Machinery with High Voltage at Very Low Frequency (ANSI) IEEE 434-1973 IEEE Guide for Functional Functional Evaluatio Evaluation n of Insulation Insulation Systems for Large High-Voltage Machines (ANSI) IEEE 446-1987 IEEE Recommended Practice for Emergency and Standby Power Systems for Industria Industriall and Commercia Commerciall ApplicaApplications (ANSI) IEEE 487-1987 IEEE Recommended Recommended Practice for the Protection Protection of Wire Line Communica Communications tions Facilitie Facilitiess Serving Serving Electric Electric Power Stations IEEE 487-1992 IEEE Recommended Recommended Practice for the Protection Protection of Wire Line Communica Communications tions Facilitie Facilitiess Serving Serving Electric Electric Power Stations IEEE 492-1974 IEEE IEEE Guide Guide for Operat Operation ion and Mainte Maintenan nance ce of Hydro Hydro Generators (ANSI) IEEE 525-1992 IEEE Guide for Design and Installation of Cable Systems in Substations IEEE 643-1980 IEEE Guide for Power-Line Carrier Applications (ANSI)
A-5
EM 1110-2-3006 30 Jun 94 IEEE 665-1987 IEEE Guide for Generating Station Grounding (ANSI) IEEE 693-1984 IEEE IEEE Reco Recomm mmen ende ded d Prac Practi tice cess for for Seis Seismi micc Desi Design gn of Substations (ANSI) IEEE 739-1984 IEEE IEEE Recomm Recommend ended ed Practi Practice ce for Energy Energy Conser Conservat vation ion and Cost-Effective Planning in Industrial Facilities (ANSI) IEEE 789-1988 IEEE Standard Standard Performan Performance ce Requireme Requirements nts for CommuniCommunicati cation onss and and Cont Contro roll Cabl Cables es for for Appl Applic icat atio ion n in High High Voltage Environments (ANSI) IEEE 810-1987 IEEE IEEE Stan Standa dard rd for for Hydr Hydrau auli licc Turb Turbin inee and and Gene Genera rato torr Integrally Forged Shaft Couplings and Shaft Runout Tolerances (ANSI) IEEE 944-1986 IEEE Application Application and Testing Testing of Uninterrup Uninterruptibl tiblee Power Supplies for Power Generating Stations (ANSI) IEEE 979-1984 IEEE Guide for Substation Fire Protection (ANSI) IEEE 980-1987 IEEE Guide for Containment and Control of Oil Spills in Substations (ANSI) IEEE 999-1992 IEEE Recommende Recommended d Practice Practice for Master/Rem Master/Remote ote SuperSuperviso visorry Cont Contro roll and and Data Data Acqu Acquis isit itio ion n (SCA (SCADA DA)) Communication IEEE 1020-1988 IEEE IEEE Guide Guide for Contro Controll of Small Small Hydroe Hydroelec lectri tricc Power Power Plants (ANSI) IEEE 1050-1989 IEEE Guide for Control Equipment Grounding in Generating Stations IEEE 1095-1989 IEEE IEEE Guide Guide for Instal Installat lation ion of Vertic Vertical al Genera Generator torss and Generator/Motors for Hydroelectric Applications IEEE 1119-1988 IEEE IEEE Guid Guidee for for Fenc Fencee Safe Safety ty Clea Cleara ranc nces es in Elec Electr tric ic-Supply Stations (ANSI)
A-6
IEEE C37.010 (with Supplements .010 b and e)-1979 IEEE IEEE Applic Applicati ation on Guide Guide for AC High-V High-Volt oltage age Circui Circuitt Breakers Rated on a Symmetrical Current Basis (ANSI) IEEE C37.011-1979 IEEE Applicati Application on Guide for Transient Transient Recovery Voltage for AC High-V High-Volt oltage age Circuit Circuit Breake Breakers rs Rated Rated on a SymSymmetrical Current Basis (ANSI) IEEE C37.04 (with Supplements .04 f, g, h)-1979 IEEE IEEE Standa Standard rd Rating Rating Struct Structure ure for AC High-V High-Volt oltage age Circui Circuitt Breake Breakers rs Rated Rated on a Symmet Symmetric rical al Curren Currentt Basis Basis (ANSI) IEEE C37.081-1981 IEEE IEEE Guid Guidee for for Synt Synthe heti ticc Faul Faultt Test Testin ing g of AC High High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis (ANSI) IEEE C37.09 (with Supplements .09 c and e)-1979 IEEE IEEE Stan Standa dard rd Test Test Proc Proced edur uree for for AC High High-V -Vol olta tage ge Circui Circuitt Breake Breakers rs Rated Rated on a Symmet Symmetric rical al Curren Currentt Basis Basis (ANSI) IEEE C37.1-1987 IEEE Standard Definitions, Specification, and Analysis of Systems Systems Used for Supervisor Supervisory y Control, Control, Data Acquisition Acquisition and Automatic Control (ANSI) IEEE C37.11-1979 IEEE Applicati Application on Guide for Transient Transient Recovery Voltage for AC High-V High-Volt oltage age Circuit Circuit Breake Breakers rs Rated Rated on a SymSymmetrical Current Basis (ANSI) IEEE C37.13-1990 IEEE IEEE Stan Standa dard rd for for LowLow-Vo Volt ltag agee AC Powe Powerr Circ Circui uitt Breakers Used in Enclosures (ANSI) IEEE C37.14-1979 IEEE IEEE Stan Standa dard rd for for LowLow-Vo Volt ltag agee DC Powe Powerr Circ Circui uitt Breakers Used in Enclosures (ANSI) IEEE C37.20.1-1987 IEEE IEEE Standa Standard rd for MetalMetal-Enc Enclos losed ed Low-Vo Low-Volta ltage ge Power Power Circuit Breaker Switchgear (ANSI) IEEE C37.29-1981 IEEE IEEE Standa Standard rd for Low-Vo Low-Volta ltage ge AC Power Power Circui Circuitt ProProtectors Used in Enclosures (ANSI)
EM 1110-2-3006 30 Jun 94 IEEE C37.30-1992 IEEE IEEE Standa Standard rd Defini Definitio tions ns and Requir Requireme ements nts for HighHighVoltage Air Switches IEEE IEEE C37. C37.34 34 (wit (with h Supp Supple leme ment ntss .34 .34 a, b, d, and and e)e)1979 IEEE Standard Test Code for High-Voltage Air Switches (ANSI) IEEE C37.35-1976 IEEE Guide for the Applicatio Application, n, Installat Installation, ion, Operation, Operation, and Maintenance of High-Voltage Air Disconnecting and Load Interrupter Switches (ANSI) IEEE C37.36B-1990 IEEE IEEE Guide Guide to Curren Currentt Interr Interrupt uption ion with with Horn-G Horn-Gap ap Air Switches (ANSI) IEEE C37.37-1979 IEEE IEEE Stan Standa dard rd Load Loadin ing g Guid Guidee for for AC High High-V -Vol olta tage ge Switches (in excess of 1000 volts) (ANSI) IEEE C37.38-1989 IEEE Standard for Gas-Insulated Metal-Enclosed Disconnecting, Interrupter, and Grounding Switches IEEE C39.96-1988 IEEE Guide for AC Motor Protection (ANSI) IEEE C57.12.01-1989 IEEE Standard Standard General General Requireme Requirements nts for Dry-Type Dry-Type Distribution tribution and Power Transformers Transformers Including Including Those with Solid Cast and/or Resin-Encapsulated Windings (ANSI) IEEE C57.12.12-1980 IEEE Guide for Installation of Oil-Immersed EHV Transformers 345 kV and Above (ANSI) IEEE C57.13.1-1981 (Reaffirmed 1986) IEEE Guide for Field Testing of Relaying Current Transformers (ANSI) IEEE C57.19.00-1991 IEEE General Requirements and Test Procedure for Outdoor Power Apparatus Bushings (ANSI) IEEE C57.19.101-1989 IEEE IEEE Tria Triall-Us Usee Guid Guidee for for Load Loadin ing g Powe Powerr Appa Appara ratu tuss Bushings
Transf Transform ormers ers up to and Includ Including ing 100 MVA MVA with with 55 °C or 65 °C Winding Rise (ANSI) IEEE C57.94-1982 IEEE Recommended Practice for Installation, Application, Operation and Maintenance of Dry-Type General Purpose Distribution and Power Transformers (ANSI) IEEE C57.106-1991 IEEE Guide for Acceptance Acceptance and Maintenance Maintenance of InsulatInsulating Oil in Equipment IEEE C57.109-1985 IEEE Guide for Transformer Through-Fault Current Duration (ANSI) IEEE C57.113-1991 IEEE Guide for Partial Discharge Measurement in LiquidFilled Power Transformers and Shunt Reactors IEEE C57.114-1990 IEEE IEEE Seis Seismi micc Guid Guidee Reactors (ANSI)
for for Powe Powerr
Tran Transf sfor orme mers rs and and
IEEE C57.115-1991 IEEE IEEE Guide Guide for Loadin Loading g Minera Mineral-O l-Oilil-Imm Immers ersed ed Power Power Transformers Rated in Excess of 100MVA (65C Winding Rise) (ANSI) IEEE C62.22-1991 IEEE IEEE Guide Guide for the Applic Applicati ation on of MetalMetal-Oxi Oxide de Surge Surge Arresters for Alternating Current Systems (ANSI) IEEE C62.92-1987 IEEE Guide for the Application of Neutral Grounding in Electric Utility Systems, Part I-Introduction (ANSI) IEEE C62.92.1-1987 IEEE Guide for the Application of Neutral Grounding in Electric Utility Systems, Part I - Introduction (ANSI) IEEE C62.92.2-1989 IEEE Guide for the Application of Neutral Grounding in Electric Electric Utility Utility Systems, Systems, Part II-Grounding II-Grounding of SynchroSynchronous Generator Systems (ANSI) IEEE C62.92.5-1992 IEEE Guide for the Application of Neutral Grounding in Electric Electric Utility systems, systems, Part V - Transmiss Transmission ion Systems Systems and Subtransmission Systems
IEEE C57.92-1981 IEEE IEEE Guide Guide for Loadin Loading g Minera Mineral-O l-Oilil-Imm Immers ersed ed Power Power
A-7
EM 1110-2-3006 30 Jun 94 NEMA ICS 1-1983 Industrial Control and Systems
UL 514B-1982 Fittings for Conduit and Outlet Boxes
NEMA ICS 2-1988 Industrial Control Devices, Controllers and Assemblies
UL 845-1987 The Standard for Motor Control Centers
NEMA ICS 6-1983 Enclosures for Electrical Controls and Systems
UL 1066-1985 The Standard for Low-Voltage AC and DC Power Circuit Breakers Breakers Used in Enclosures Enclosures
NEMA PB 1-1990 Panelboards NEMA PB 2-1989 Deadfront Distribution Switchboards NEMA ST 20-1986 Dry-Type Transformers for General Applications NEMA VE 1-1984 Metallic Cable Tray Systems NEMA WC 50-1976 Ampacities, Including Effect of Shield Losses for SingleConduc Conductor tor SolidSolid-Die Dielec lectri tricc Power Power Cable Cable 15 kV throug through h 69 kV NEMA WC 51-1986 Ampacities of Cables in Open-Top Cable Trays NEMA WD 1-1983 Wiring Devices NFPA 70-1993 National Electrical Code UL 6-1981 Rigid Metal Conduit UL 467-1984 Grounding and Bonding Equipment
A-8
UL 1072-1988 The Standard for Medium-Voltage Power Cables UL 1236-1986 The Standard for Battery Chargers UL 1277-1988 The The Stan Standa dard rd for for Elec Electr tric ical al Powe Powerr and and Cont Contro roll Tray Tray Cables with Optional Optical-Fiber Members UL 1558-1983 The Standa Standard rd for MetalMetal-Enc Enclos losed ed Low-Vo Low-Volta ltage ge Power Power Circuit Breaker Switchgear UL 1561-1988 The Standard for Large General Purpose Transformers UL 1564-1985 The Standard for Industrial Battery Chargers UL 1569-1985 The Standard for Metal-Clad Cables Beeman Beeman, D. L., Ed., Industrial Power Systems Handbook . New York: McGraw-Hill, McGraw-Hill, 1955. Helms Illuminating g Engineering Engineering for Energy Energy EffiHelm Helms, s, R. N. Illuminatin York: Prentice Prentice-Hall -Hall.. ciency. New York:
EM 1110-2-3006 30 Jun 94
Appendix B Power Transformer Studies and Calculations
(3) Transform Transformer er data: - 46,000 kVA - 13.2 kV /115 kV - two-winding - 1φ - FOA type cooling
B-1. Recommended Recommended Studies Studies a. The following following studies studies should be performed performed during
the preliminary design phase for generator step-up power transformers:
B-3. B-3. Sample Sample Study Study B1, BIL / Surge Surge Arreste Arresterr Coordination a.
Obje Object ctiv ive. e.
(1) Transforme Transformerr kVA Rating Study. The objective of this study is to determine the following: (2) Transforme Transformerr Cooling Cooling Study. Study. (3) (3) Basi Basicc Impu Impuls lsee Insu Insula lati tion on Leve Levell (BIL (BIL)) / Surg Surgee Arrester Coordination Study.
(1) Transform Transformer er high-voltage high-voltage basic impulse impulse insulation insulation levels (BIL’s). (2) Transform Transformer er impulse impulse curves. curves.
(4) Transforme Transformerr Bushings Bushings Rating Rating Study. (3) Surge arrest arrester er type and and sizing. sizing. (5) Transforme Transformerr Efficiency Efficiency Study. Study. (4) Surge arrest arrester er impulse impulse curves. curves. (6) Transforme Transformerr Loss Evaluation Evaluation Study. Study. (7) System System Fault Fault Study Study for Transf Transform ormer er Impeda Impedance nce Determination.
(5) Transf Transform ormer er high-v high-volt oltage age BIL / surge surge arrest arrester er coordination. b.
Refer Referen ence ces. s.
b. This append appendix ix outlin outlines es sample sampless of these these studie studiess
and calculation calculationss as listed above. Sample Sample studies for items items (a) and (b) are not included due to their lesser degree of complexity and site-specific nature (a discussion concerning transf transform ormer er rating ratingss and coolin cooling g consid considera eratio tions ns is includ included ed in Chapte Chapterr 4). A system system fault fault study study should should be performed performed prior prior to determini determining ng transform transformer er impedances impedances.. A sample system fault study is not included in this appendix due to its expanded scope and site-specific nature.
The following references were used in the performance of this this study. study. Comple Complete te citatio citations ns can be found found in AppenAppendix A of this document, “References.” (1) ANSI C62.1-1984. C62.1-1984. (2) ANSI C62.2-1987. C62.2-1987. (3) ANSI C62.11-1987 C62.11-1987..
B-2. Data Used Used for Sample Sample Studies Studies (4) ANSI/IEEE ANSI/IEEE C57.12.00-19 C57.12.00-1987. 87. a. The sample sample studies shall be based upon the followfollow-
ing assumed data: (1) Transmiss Transmission ion line line data: data: - 230 kV L-L - 750 kV BIL BIL rating
(5) ANSI/IEEE ANSI/IEEE C57.12.14-19 C57.12.14-1982. 82. (6) ANSI/IEEE ANSI/IEEE C57.12.90-19 C57.12.90-1987. 87. (7) ANSI/IEEE ANSI/IEEE C57.98-1986 C57.98-1986.. The proposed transformer transformer replacement ment will will be two two wind windin ing, g, sing single le-p -pha hase se,, 60-H 60-Hz, z, FOA FOA cooled cooled units, units, 65 °C rise, rise, connec connected ted delta/ delta/wye wye,, with with the following ratings: c.
(2) Generator Generator data: - 69,000 kVA - 110 kV winding winding BIL
Proc Proced edur ure. e.
B-1
EM 1110-2-3006 30 Jun 94 Transform Transformer er bank: bank: Three-1 Three-1φ, 46,000 kVA, 13.2 kV /230 kV . These transformer transformerss are considered considered to be a “replaceme “replacementntin-kind.” Transformer high-voltage high-voltage basic impulse insulation (1) Transformer levels (BIL’s).
(a) Line Line BIL characte characteris ristic tics. s. The Power Power Marketin Marketing g Authority Authority’s ’s (PMA’s) (PMA’s) transmiss transmission ion line, line, transform transformer er highvoltage voltage insulatio insulation, n, high-volta high-voltage ge bushing bushing BIL character characterisistics, and surge arrester duty-cycle ratings are as follows:
Chopped-wave withstand voltage levels for different transformer former high-v high-volt oltage age BIL rating ratingss are listed listed in Table Table 5 of ANSI/ ANSI/IE IEEE EE C57.1 C57.12. 2.00 00.. Thes Thesee leve levels ls corr corres espo pond nd to 1.1 × BIL, and the time-to-chop occurs at 3.0 µs. Table B-2 CWW Withstand Voltage Line Voltage, kV
BIL Rating, kV
CWW Strength, kV
230 230 230
65 0 75 0 82 5
71 5 82 5 90 5
230-kV System: System: •
(c) Full-wave Full-wave (BIL) (BIL) withstand withstand voltage. voltage.
Transm Transmiss ission ion line: line: approx approxima imatel tely y 750 750 kV BIL
• Tran Transf sfor orme merr high high-v -vol olta tage ge insu insula lati tion on:: 650 kV BIL •
typi typica call lly y
(d) Switching Switching impulse impulse level (BSL) withstand withstand voltage. voltage.
High-v High-volt oltage age bushin bushings: gs: typica typically lly 750 kV BIL B IL
• Surge Surge arrest arrester er rating rating:: typica typically lly 180 kV duty-cycle rating (b) This study will analyze transformer transformer high-voltag high-voltagee BIL levels of 650 kV , 750 kV , and 825 kV , for the 230-kV tran transm smis issi sion on line line,, and and dete determ rmin inee the the corr correc ectt leve levell of protection. curves. (2) Transformer impulse curves.
(a) Front-Of-W Front-Of-Wave ave (FOW) withstan withstand d voltage. voltage. As indica indicated ted by ANSI ANSI C62.2, C62.2, the FOW streng strength th range range should be between 1.3 and 1.5 times the BIL rating, with time-totime-to-chop chop occurring occurring at 0.5 µs. For the purposes purposes of this coordi coordinat nation ion study, study, an FOW streng strength th of 1.4 times times BIL shall be used. Table B-1 FOW Withstand Voltage Line Voltage, kV
BIL Rating, kV
FOW Strength, kV
230 230 230
650 750 825
910 1050 1155
(b) Chopped-wave Chopped-wave (CWW) (CWW) withstand withstand voltage. voltage.
B-2
The full-wave withstand voltage is equivalent to the highvoltag voltagee BIL rating rating of the transfo transforme rmer. r. This This withst withstand and voltage occurs as a straight line from 8 to 50 µsec.
Switching Switching impulse impulse withstand withstand voltage voltage levels levels for different different transformer high-voltage BIL ratings are listed in Table 5 of ANSI/IEE ANSI/IEEE E C57.12 C57.12.00 .00.. These These levels levels corres correspon pond d to 0.83 × BIL, and extend from 50 to 2,000 µsec. Table B-3 BSL Withstand Voltage Line Voltage, kV
BIL Rating, kV
BSL Strength, kV
230 230 230
65 0 75 0 82 5
54 0 62 0 68 5
(e) Applied Applied voltage voltage test level. level. Applied voltage test levels for different transformer highvoltag voltagee BIL rating ratingss are listed listed in Table Table 5 of ANSI/I ANSI/IEEE EEE C57.12.00. Table B-4 APP Voltage Voltage Line Voltage, kV
BIL Rating, kV
APP Strength, kV
230 230 230
65 0 75 0 82 5
27 5 32 5 36 0
EM 1110-2-3006 30 Jun 94 (f) Transforme Transformerr impulse impulse curve generation generation.. The transtransformer impulse curve is generated as indicated in Figure 3 of ANSI C62.2. C62.2. As discussed discussed in in Figure 3: 3: It is not possib possible le to interp interpola olate te exactl exactly y betwee between n poin points ts on the the curv curve. e. Good Good expe experi rien ence ce has has been been obtained with the assumptions implicit in the preceding ceding rules: rules: (a) The The full BIL strength strength will apply apply for front front times between between 8 and 50 µs. (b) Minimum Minimum switching switching surge withstand occurs between 50 and 2,000 2,000 µs. µs. Refer Refer to the attach attached ed plot of the transtransformer former impulse impulse curves curves located located at the end of this this study. arrester type and sizing. (3) Surge arrester
(a) Genera General. l. The objec objectiv tivee for surge surge protec protectio tion n of a power system is to achieve at a minimum cost an acceptably low level of service interruptions and an acceptably low level level of transf transform ormer er failur failures es due to surgesurge-rel relate ated d events. (b) (b) Arre Arrest ster er type type.. Surg Surgee arre arrest ster erss util utiliz izin ing g meta metalloxide (such as zinc-oxide) valve (MOV) elements will be used used due to the extrem extremee improv improveme ement nt in nonlin nonlinear earity ity as compared to arresters with silicon-carbide valve elements. This nonlinear nonlinear character characteristi isticc of the voltage-cu voltage-current rrent curve provides provides better better transform transformer er protectio protection n and improves improves the arrester’s thermal stability. (c) (c) Arre Arrest ster er clas class. s. Stat Statio ion n clas classs arre arrest ster erss shal shalll be utilized, based on system line voltage of 230 kV . (d) Arrest Arrester er sizing sizing.. It is desirabl desirablee to select select the miniminimum-sized arrester that will adequately protect the transformer former insulation insulation from damaging damaging overvolta overvoltages, ges, while not self-destr self-destructin ucting g under any reasonabl reasonably y possible possible series series of even events ts at the the loca locati tion on in the the syst system em.. Sinc Sincee the the meta metalloxide valve in MOV arresters carries all or a substantial portion of total arrester continuous operating voltage, the most most import important ant criter criterion ion for select selection ion of the minimu minimum m arrest arrester er size size is the continuo continuous us operat operating ing voltage. voltage. SelecSelection of a size for an arrester to be installed on grounded neutral systems is based upon: • The The maxi maximu mum m cont contin inuo uous us oper operat atin ing g volt voltag agee (MCOV), line-to-neutral, at the arrester location computed as the maximum system voltages divided by root-three. • The The assu assump mpti tion on that that the the syst system em is effe effect ctiv ivel ely y grou ground nded ed wher wheree a faul faultt is expe expect cted ed to init initia iate te circ circui uitt breaker operation within a few cycles.
(e) (e) Mini Minimu mum m arre rrester ster sizi sizing ng for sys system tem line ine voltage. voltage. Based upon ANSI C57.12.00, C57.12.00, the relations relationship hip of nominal system voltage to maximum system voltage is as follows: Nomi Nomina nall Syst System em Volt Voltag agee
Maxi Maximu mum m Syst System em Volt Voltag agee
230 kV
242 kV
(4) The minimum minimum arrest arrester er sizing sizing in MCOV for the system line voltage shall, therefore, be as follows: • Arrest Arrester er MCOV MCOV ratin rating g = 242 kV / / √ 3 = 139.7 kV 1-n • Thi This calc alcula ulated ted arre arresster ter rati rating ng of 139. 139.7 7 kV 1-n MCOV for the 230- kV line voltage corresponds to a standard dard arrest arrester er voltag voltagee rating rating of 140 kV 1-n MCOV MCOV and and a duty-cycle voltage of 172 kV 1-n, as outlined in Table 1 of ANSI C62.11. C62.11. (5) Line Line voltag voltages es at the powerhou powerhouse se are commonl commonly y operated between the nominal and maximum system voltages. ages. Based Based on this, this, the surge surge arreste arresterr should should be sized somewhat higher than the maximum system line-to-neutral volt voltag agee rati rating ng of the the line line to avoi avoid d over overhe heat atin ing g of the the arrester arrester during during normal operating operating conditions. conditions. The arrester arrester rating rating chosen chosen shall shall be one MCOV step step higher higher than the recommende recommended d MCOV for grounded neutral neutral circuits. circuits. The following arrester MCOV values have been chosen: • Arrest Arrester er MCOV MCOV ratin rating g = 144 kV • Arrester Arrester duty-c duty-cycle ycle rating rating = 180 kV
B-4. Surge Arrester Arrester Impulse Impulse Curves Curves For the purposes of this coordination study, surge arrester voltage withstand levels shall be assumed to correspond to typica typicall manufa manufactu cturer rer’s ’s data. data. These These voltag voltagee withst withstand and volt voltag agee leve levels ls shal shalll be used used for for the the gene genera rati tion on of the the arrester arrester curves curves and the coordinati coordination on study. Gapped Gapped design MOV surge surge arrest arresters ers are typica typically lly used used for distri distribut bution ion class class transformers transformers.. The gapless design design surge arrester arrester shall be addres addressed sed in this this study, study, since since it repres represent entss a typica typicall MOV type arrester suitable for these applications. a. Maximu Maximum m 0.5 µs µs discha discharge rge volta voltage ge (FOW). (FOW). The discharge voltage for an impulse current wave which produces duces a voltag voltagee wave wave cresti cresting ng in 0.5 µs is correl correlati ative ve to the front-of-wa front-of-wave ve sparkover sparkover point. The discharge discharge currents used used for for stat statio ion n clas classs arre arrest ster erss are are 10 kA for for arre arrest ster er
B-3
EM 1110-2-3006 30 Jun 94 MCOV MCOV from from 2.6 2.6 thro throug ugh h 245 245 kV . As tak takeen from from the the manufacturer’s protective characteristics, 230 kV line line voltage (144 kV arrester arrester MCOV) Maximum 0.5 µs discharge voltage = 458 kV b. Maximu Maximum m 8 × 20 µs curr curren entt disc discha harg rgee volta voltage ge (LPL). Disc Discha harg rgee volt voltag ages es resu result ltin ing g when when ANSI ANSI
8 × 20 20 µs µs curr curren entt impu impuls lses es are are disc discha harg rged ed thro throug ugh h the the arrester are listed in the manufacturer’s data from 1.5 kA throu hrough gh 40 kA. kA. For For coor coordi dina nati tion on of the 8 × 20 µs current-wave discharge voltage with full-wave transformer withstand voltage, a value of coordination current must be sele select cted ed.. To accu accura rate tely ly dete determ rmin inee the the maxi maximu mum m disdischarge currents, the PMA was contacted and the following line fault currents were obtained:
Table B-5 Surge Arrester Coordination MOV MOV Arre Arres ster ter Prot Protec ecti tive ve Level
Tran Transf sfor orme merr Withs ithsta tand nd Level
Maximum Maximum 0.5 µ s disc ischarg harge e voltage - “FOW”
Cho Chopped pped-w -wa ave with withs stan tand “CWW”
Maximum 8 × 20 µ s current discharge voltage - “LPL”
Full-wave wit hs hst an and “BIL”
Maximum switching surge 45 × 90 µ s discharge voltage - “SSP”
Switching surge withstand “BSL”
At each of the above above three three points points on the transtransformer former withstand withstand curve, a protectiv protectivee margin margin with respect to the surge arrester protective curves is calculated as: b.
Transmission Line (230 kV ): ): 3φ fault................17010 Amperes line-ground fault..15910 Amperes c. Maximum Maximum switching switching surge surge protec protective tive level (SSP). (SSP).
The fast fast switch switching ing surge surge (45 × 90 90 µs) discha discharge rge voltag voltagee defines defines the arresters’ arresters’ switching switching surge protective protective level. As taken from the manufacturer’s protective characteristics,
(Transformer Withstand) (Protective Level)
1 × 10 100
The protective protective margin margin limits for coordinati coordination, on, as specified in ANSI C62.2, are as follows: c.
(1) % PM (CWW/F (CWW/FOW) OW) ≥ 20 (2) % PM (BIL/L (BIL/LPL) PL) ≥ 20
230 kV line line voltage (144 kV arrester arrester MCOV) Maxi aximum mum swit switch chiing sur surge prot rotect ective ive leve evel classifying 1,000 ampere current level = 339 kV .
% PM
at
d. 60-Hz 60-Hz tempora temporary ry overvo overvoltag ltagee capabil capability. ity. Surge arrest arresters ers may infreq infrequen uently tly be requir required ed to withst withstand and a 60-Hz 60-Hz voltage voltage in excess excess of MCOV. MCOV. The most most common common cause is a voltage rise on unfaulted phases during a lineto-gro to-ground und fault. fault. For the arrest arrester er being being addres addressed sed for the purposes of this coordination, the arrester could be energized at 1.37 × MCOV for a period of 1 min.
230-kV line line voltage (144- kV arrester arrester MCOV) 60-Hz temporary overvoltage capability: 144 kV × × 1.37 = 197.3 kV
B-5. Transforme Transformerr High-Voltage High-Voltage BIL/Surge BIL/Surge Arrester Coordination
(3) % PM (BSL/S (BSL/SSP) SP) ≥ 15 d. The protecti protective ve margin marginss for the MOV arrester arresterss selected yield protective margins of: Transformerr BIL = 650 kV . (1) Transforme
(a) (a) % PM (CWW (CWW/F /FOW OW)) = (715 (715 kV /458 kV - 1) × 100 = 56% (b) % PM (BIL/L (BIL/LPL) PL) = (650 (650 kV /455 kV - 1) × 100 = 43% (c) % PM (BSL (BSL/SS /SSP) P) = (540 (540 kV /339 kV - 1) × 100 = 59% Transformerr BIL = 750 kV . (2) Transforme
a. Coordinat Coordination ion betwee between n MOV arrest arresters ers and transtrans-
(a) (a) % PM (CWW (CWW/F /FOW OW)) = (825 (825 kV /458 kV - 1) × 100 = 80%
former former insulation insulation is checked checked by comparing comparing the following following points points of transf transform ormer er withst withstand and and arrest arrester er protec protectiv tivee levels on the impulse curve plot:
(b) % PM (BIL/ (BIL/LPL LPL)) = (750 kV /455 kV - 1) × 100 = 65%
B-4
EM 1110-2-3006 30 Jun 94 (c) % PM (BSL/ (BSL/SSP SSP)) = (620 (620 kV /339 kV - 1) × 100 = 83% Transformer BIL = 825 kV . (3) Transformer
(a) (a) % PM (CW (CWW/FO W/FOW W) = (905 (905 kV /458 kV - 1) × 100 = 98% (b) % PM (BIL/L (BIL/LPL) PL) = (825 (825 kV /455 kV - 1) × 100 = 81% (c) % PM (BSL/ (BSL/SSP SSP)) = (685 (685 kV /339 kV - 1) × 100 = 102% d.
(5) (5) Main Main Unit Unit Gene Genera rato torr Step Step-u -up p Tran Transf sfor orme merr Replacement, BIL / Surge Arrester Coordination Study. As summar summarize ized d in the referenc referenced ed studies, the transformers shall be rated as follows: c.
Proc Proced edur ure. e.
46,000 kVA 13.2 kV /230 kV Y Y 750 kV High-Voltage High-Voltage Winding BIL 110 kV Low-Voltage Low-Voltage Winding BIL d.
Bushin Bushing g ratings ratings and and charact characteri eristic stics. s. As outlined
in IEEE Std. 21-1976, 21-1976, performanc performancee character characteristi istics cs based upon definite conditions shall include the following:
Summ Summar ary. y.
• Rated maximum maximum line-to line-to-grou -ground nd voltage voltage (1) (1) As note noted d from from the trans ransfo forrmer BIL BIL / sur surge arrest arrester er coordi coordinat nation ion plots plots (Figur (Figuree B-1), B-1), the minim minimum um prot protec ecti tive ve marg margin inss are are much much grea greate terr than than the the desi design gn standa standards rds,, due to the better better protec protectiv tivee charac character terist istics ics of MOV surge arresters.
• Rated Rated freque frequency ncy • Rated dielectri dielectricc strengt strengths hs • Rated continuous continuous currents currents
(2) A high-voltag high-voltagee winding winding BIL rating rating of 750 kV BIL for the 230230-kV nominal nominal system system voltage voltage shall shall be selected selected for the transf transform ormers ers.. These These BIL selectio selections ns will will provid providee the follow following ing advant advantage ages: s: (a) reduct reduction ion in transf transform ormer er procur procureme ement nt costs, costs, (b) reduct reduction ion in transf transform ormer er losses losses,, (c) better coordination with the BIL rating structure of the system, and (d) reduction in the physical size of the transformer former.. Item Item (d) is due conside considerat ration ion because because of vault vault size limitations.
B-6. Sample Study Study B2, Transformer Transformer Bushings Bushings Rating a.
Objec Objectiv tive. e. The objective objective of this study is to deterdeter-
mine mine the the prop proper er rati rating ngss for for the the bush bushin ings gs and and bush bushin ing g current transformers on the replacement generator step-up (GSU) transformers. b. Refe Refere renc nces es.. The following following references references were used in the performance performance of this study. study. Complete Complete citations citations can be found in Appendix A of this document, “References.”
(1) ANSI C76.1-197 C76.1-1976 6 / IEEE Std. 21-1976 21-1976.. (2) ANSI C76.2-197 C76.2-1977 7 / IEEE Std. 24-1977 24-1977.. (3) ANSI C57.13-1978 C57.13-1978..
The bushings bushings will not be subjec subjectt to any unusual unusual servic servicee conditions. line-to-ground d voltage. (1) Rated maximum line-to-groun
(a) Based Based upon ANSI C57.12 C57.12.00, .00, the relation relationshi ship p of nominal system voltage to maximum system voltage is as follows: Nomi Nomina nall Syst System em Volt Voltag agee
Maxi Maximu mum m Syst System em Volt Voltag agee
230 kV
242 kV
(b) The maximum maximum line-to-gro line-to-ground und voltage voltage is therefore therefore:: Maximum Line Line-T -Too-Gr Grou ound nd Volt Voltag agee
Maxi Maximu mum m Syst System em Volt Voltag agee 242 kV
139.7 kV
(c) Line Line voltag voltages es are common commonly ly operat operated ed betwee between n the nominal nominal and maximum maximum system system voltag voltages. es. Based Based on this, this, the select selection ion of maximu maximum m line-t line-to-g o-grou round nd voltag voltages es will will be chosen chosen as 5 perc percent ent higher higher than than the ANSI sugsuggested values to avoid overheating of the bushings during normal normal operating operating conditions. conditions. This leads to bushing selecselections with the following Rated Maximum Line-To-Ground Voltage, Insulation Class, and BIL characteristics:
(4) (4) Main Main Unit Unit Gene Genera rato torr Step Step-u -up p Tran Transf sfor orme merr Replacement, Transformer kVA Rating Study.
B-5
EM 1110-2-3006 30 Jun 94
B-6
EM 1110-2-3006 30 Jun 94 •
Line Line Volt Voltag age: e: 230 230 kV
•
Bushin Bushing g Insula Insulatio tion n Class: Class: 196 kV
•
Bush Bushin ing g BIL: BIL: 900 900 kV
•
Rated Rated Maxi Maximum mum Line-t Line-to-G o-Grou round nd Volt Voltage age:: 146 kV
(d) The low-voltage low-voltage terminal terminal bushings bushings shall be insulate lated d at the the same same BIL BIL as the the gene genera rato torr wind windin ings gs,, i.e. i.e.,, 110 kV BIL. BIL. This This corres correspon ponds ds to an insulat insulation ion class class of 15 kV .
• Choppe Chopped d Wave Wave Impu Impulse lse - kV Crest, Crest, 2µsec Withstand Withstand:: 142 kV • Choppe Chopped d Wave Wave Impu Impulse lse - kV Crest, Crest, 3µsec Withstand Withstand:: 126 kV (c) Neutral Neutral bushings. bushings. • 60 Hz, 1-min 1-min Dry Voltag Voltagee Withsta Withstand nd Test: Test: 60 kV rms • 60 Hz, 10-sec 10-sec Wet Wet Voltage Voltage Withst Withstand and Test: Test: 50 kV rms
(e) The neutral neutral terminal terminal bushings bushings shall be insulate insulated d at 150 kV BIL, BIL, corr corres espo pond ndin ing g to an insu insula lati tion on clas classs of 25 kV .
150 kV
frequency. The (2) Rated frequency. The freq freque uenc ncy y at whic which h the the bushings shall be designed to operate is 60 Hz.
• Choppe Chopped d Wave Wave Impu Impulse lse - kV Crest, Crest, 2µsec Withstand Withstand:: 194 kV
(3) Rated dielectric dielectric dielectric strengths. strengths. The rated dielectric strengths for the transformer bushings, expressed in terms of specif specific ic values values of voltag voltagee withst withstand and tests, tests, shall shall be as follows:
• Choppe Chopped d Wave Wave Impu Impulse lse - kV Crest, Crest, 3µsec Withstand Withstand:: 172 kV
(a) (a) 230 230 kV system system high-voltage bushings. • 60 Hz, Hz, 1-min 1-min Dry Dry Voltag Voltagee Withst Withstand and Test Test:: 425 kV rms rms • 60 Hz, Hz, 10-sec 10-sec Wet Wet Volta Voltage ge Withs Withstan tand d Test: Test: 350 kV rms rms • Full Wave Impulse Impulse Voltage Voltage Withs Withstand tand Test: 900 kV
• Full Wave Wave Impulse Impulse Voltage Voltage Withsta Withstand nd Test:
currents. (4) Rated continuous currents.
(a) The following following are are the rated currents currents for for the transtransformer former bank, based based upon upon the maximu maximum m k VA VA generatin generating g capacity of each generating unit: • Two Two gene genera rato tors rs shal shalll be conn connec ecte ted d to the the tran transsformer former bank. bank. The maxim maximum um k VA VA rating of each generator tor is 69,0 69,000 00 k VA. V A. The The tota totall of the gener generat ator or rated rated currents for these units is, therefore: I
• Choppe Chopped d Wave Wave Impuls Impulsee - kV Crest, Crest, 2µsec Withstand Withstand:: 1160 kV • Choppe Chopped d Wave Wave Impuls Impulsee - kV Crest, Crest, 3µsec Withstand Withstand:: 1040 kV
• 60 Hz, Hz, 1-min 1-min Dry Dry Voltag Voltagee Withst Withstand and Test Test:: 50 kV rms rms •
60 Hz, Hz, 10-sec 10-sec Wet Wet Volta Voltage ge Withs Withstan tand d Test: Test: 45 kV rms rms • Full Wave Impulse Impulse Voltage Voltage Withs Withstand tand Test: 110 kV
(2)69,000 kVA
3 V L
3 (13. (13.8 8 kV )
5,774 Amps
• Total Total rated rated low-vo low-volta ltage ge termi terminal nal current current for delta delta connected transformers: I
(b) (b) 13.2 13.2 kV low-voltage low-voltage bushings.
2S 3φ
I
5,774 Amps
3
3
3,334 Amps
• Rated Rated line line curren current: t: I L 5,774 Amps ×
13.2 kV 230 kV
331 Amps
(b) Based on the above above data, the the suggested suggested minimum minimum bushing bushing rated rated current current requireme requirements nts shall be as follows: follows:
B-7
EM 1110-2-3006 30 Jun 94 • High-V High-Volt oltage age Bushing Bushing Minimu Minimum m Curren Currentt Rating Rating:: 400 Amperes
(6) Determine Determine the losse losses. s. (7) Determine Determine transforme transformerr estimate estimated d efficienc efficiency. y.
• Neut Neutrral 400 Amperes
Bush Bushiing
Mini Minim mum
Cur Current rent
Rati Rating ng::
• Low-Vo Low-Volta ltage ge Bushing Bushing Minimu Minimum m Curren Currentt Rating Rating:: 3,500 Amperes
Tran Transsfor former mer bank bank:: 46,0 46,000 00 k VA, 1φ, 13.2 13.2 kV /230 kV Y, FOA cooled transformers. d.
Transformer BIL rating. rating. (1) Transformer
e. Bush Bushin ing g curr curren entt tran transfo sform rmer er (CT (CT)) ratin ratings gs and and characteristics. Two standard standard multi-ra multi-ratio tio bushing-type bushing-type
(a) Low-vol Low-voltag tagee windi windings ngs:: 110 kV BIL. BIL.
CT’s for relaying service shall be installed in each of the 230-kV transfor transformer mer high-volta high-voltage ge bushings bushings for the bank, confor conformin ming g to accura accuracy cy classi classific ficati ation on ’C’, ’C’, rated rated 400/5. 400/5. Thes Thesee CT’s CT’s shal shalll be used used for for tran transf sfor orme merr diff differ eren enti tial al relaying and line protective relaying.
(b) High-v High-volt oltage age windin windings: gs: 750 kV BIL. BIL.
B-7. Sample Study Study B3, Transformer Transformer Efficiency Efficiency a.
The following following references references were used in the performanc performancee of this study. study. Complete Complete citations citations can be found in Appendix A of this document, “References.” Refe Refere renc nces es..
(1) (1) Main Main Unit Unit Gene Genera rato torr Step Step-u -up p Tran Transf sfor orme merr Replacement, Transformer k VA VA Rating Study. (2) (2) Main Main Unit Unit Gene Genera rato torr Step Step-u -up p Tran Transf sfor orme merr Replacement, BIL/Surge Arrester Coordination Study. (3) Westinghou Westinghouse se Electric Electric Corpor Corporation ation.. 1964 (locate (located d at end of study). The calcul calculati ations ons for estima estimatin ting g the transf transform ormer er losses losses and effici efficienc ency y calcul calculati ations ons shall shall be base based d on the the West Westin ingh ghou ouse se Tech Techni nica call Data Data Bull Bullet etin in No. 48-500 48-500.. The followi following ng steps will be used in deterdetermining this data: c.
Proc Proced edur ure. e.
(1) Determine Determine the insulation insulation level level of the transformer. transformer. (2) (2) Dete Determ rmin inee the the equi equiva vale lent nt two two wind windin ing g 65 °C reference product factors. (3) (3) Dete Determ rmin inee the the basi basicc prod produc uctt fact factor or from from the the Table A: 65 °C reference reference product product factors. factors. (4) Adjust Adjust for special special featur features. es. (5) Determine Determine the the ratio ratio of losses. losses.
B-8
Basic produc productt factor factor determ determina ination tion (Pe). Basic (3) Basic reference product factor:
Obje Objecti ctive ve.. The object objective ive of this this study study is to estiesti-
mate the transformer efficiencies for the proposed replacement generator step-up (GSU) transformers. b.
Equivalen lentt two-win two-windin ding g 65 °C self-c self-coole ooled d MVA. MVA. (2) Equiva For FOA type cooling rated at 65 °C, the specified MVA is for self-cooling.
Pe
B
A MVA MVA
MVA
(a) As taken taken from from Table Table A, A = .000159 .0001590, 0, B = .2564 .2564 (b) (b) Conv Conver ersi sion on of the the MVA(1φ) to MVA(3φ) is required to calculate the product factor. MVA(3φ) = 2 × MVA(1φ) = 2 × 46 MVA = 92 MVA
(c) Therefore, Therefore, the the base product product factor factor (Pe) is: Pe
.0001590 .0001590 92
.2564
.028257
92
Adjust Pe for % adde adders rs (P r ). The base product (4) Adjust product factor factor calcul calculate ated d in (c) should should be adjust adjusted ed furthe furtherr for special special features. features. The adjusted adjusted base product product factor, Pr , is calculated as follows:
Pr
(1
PercentAdditions
100
) × Pe
(a) From From Table Table B, on page 12 of the Westing Westinghou house se document, the percent additions are: Front of of Wave Impulse Impulse Test: Test: 5% (b) Final adjuste adjusted d base product product factor: factor: Pr = .028257 × (1+.05) = .029669
EM 1110-2-3006 30 Jun 94 (5) Loss ratio (R). The The rati ratio o of losses losses (NL kW /L kW ), ) , appl applyi ying ng to the the refe refere renc ncee prod produc uctt fact factor ors, s, for for transforme transformers rs with the high-volta high-voltage ge winding winding BIL between between 550 and 750 kV , is calculated as follows:
R = 2.75 - .182 ln 46 = 2.053 Determination of losses. losses. (6) Determination
b.
(a) The percent percent no-load no-load loss loss is given given by:
%Fe
.029669 2.053
.120214
MVA
100
Obje Object ctiv ive. e. The objective objective of this study is to estab-
Refer Referen ence ces. s. The following following reference reference was used in
the performanc performancee of this study. A complete complete citation citation can be found in Appendix A of this document, “References.” (1) (1) “Mai “Main n Unit Unit Gene Genera rato torr Step Step-U -Up p Tran Transf sfor orme merr Replacement, Transformer Efficiency Study.” (2) G ui ui de de Transformers.
(b) No-loa No-load d loss is given given by: by: No Load Loss
a.
lish the loss evaluation and penalty factors, and determine an auxiliary cooling loss evaluation factor, for use in the construction specifications for the new main unit generator step-up replacement transformers.
R = 2.75 - .182 1n MVA
P R
B-8. Sample Study Study B4, Transform Transformer er Loss Evaluation
c.
× %Fe
46 × .120 .12021 214 4 100
.055 .05529 299 9 MW
S pe pe ci ci fi fi ca cat io io n
C EE- 2 22 2 03 03 .
P ow ow er er
Disc Discus ussi sion on..
Pertinent values for computatio computations. ns. The following (1) Pertinent sample sample values values will will be used used in the computat computation ionss for loss loss evaluation:
No-Load Loss = 55.30 kW
(a) Value of replace replacement ment energy energy:: 15.94 mills mills/KW-h /KW-hrr
(c) Total Total loss loss is give given n by:
(b) Value of replacem replacement ent capacit capacity: y: $267,800/MW $267,800/MW-yr -yr = $30.57/KW-yr
Total Loss = ( R+1) × No-Load Loss Total Loss = (2.053 + 1) × 55.30 kW = = 168.83 kW
(d) Plant Plant capa capacit city y facto factor: r: 54%
(d) Load Load loss loss is given given by: by: Load Loss = Total Loss - No-Load Loss = 168.83 kW - 55.30 kW Load Loss = 113.53 kW Estimated d efficie efficiency ncy (η). (7) Estimate mated efficiency is given by:
η
MVA
46
The The trans transfo form rmer er esti esti--
MVA × 100% Total Losses
46 × 100 100% .168830
(c) Alternativ Alternativee cost of Federal financing financing interes interestt rate: 8.5%
99.6 99.63 3%
Determination of rates of evaluation. The evalu(2) Determination ation ation of transf transform ormer er effici efficienc ency y for use in determ determini ining ng award of the contract should be based on the same value per kW of loss loss used used in dete determ rmin inin ing g the the eval evalua uati tion on of efficienc efficiency y of the associated associated main generator generators. s. This value value of one one kilo kilowa watt tt of loss loss is the the capi capita tali lize zed d valu valuee of the the annual annual capaci capacity ty and energy energy losses losses based based on the averag averagee annual annual number number of hours hours of operat operation ion.. The transfo transforme rmerr load load used used for effici efficienc ency y evalua evaluatio tion n should should corres correspon pond d approximately to the generator load used for evaluation of generator generator efficienc efficiency. y. For class FOA transformers transformers,, 87 percent of rated load at 1.0 power factor shall be used.
B-9
EM 1110-2-3006 30 Jun 94
B-10
EM 1110-2-3006 30 Jun 94
B-11
EM 1110-2-3006 30 Jun 94
B-12
EM 1110-2-3006 30 Jun 94
B-13
EM 1110-2-3006 30 Jun 94 (a) The rate of evaluation evaluation for efficienc efficiency y is calculated calculated as present worth, as follows: •
Transformer loss is therefore Loss 40,020 kW 39,872 kW
148 kW
R = rate of evaluation
•
EV = = energy value
•
CV = = capacity value
•
CF = = capacity factor
•
(c) (c) Rate Rate of eval evalua uati tion on for for each each 1/10 1/100% 0% of tran transsform former er effi effici cien ency cy.. Tran Transf sfor orme merr loss losses es per per 1/10 1/100% 0% of transformer efficiency is: Loss per 1/100%
PWF = = present worth factor
148 kW 99.6 99.63) 3) × (100 (100))
(100 (100
The rate of evaluation per 1/100 percent of efficiency is:
So,
Rate of evaluation (1,175.02 R = (PWF ) ((365) (24) ( EV ) (CF ) + CV )
4,700 The present worth factor ( PWF ) for 35 years at 8.5% is: PWF
(
P ,8.5%,35) A
(1 .085) .085)35 1
× (.01594 1,175
$ KW HR
11.088 YR
.085(1 .085(1 .085)35
R (11.088YR) × ((365
DAYS HOURS ) × (24 ) YEAR DAY
) × (.54 (.54))
30.5 30.57 7
$ KW YR
)
$ KW
(b) Transf Transform ormer er efficien efficiency cy and losses losses.. Transf Transform ormer er input shall be based upon 87 percent of rated load at 1.0 powe powerr fact factor or of the the conn connec ecte ted d gene genera rato tors rs.. The The tran transsformer bank has two generators connected, each rated at 69,000 kVA at 1.0 power power factor. factor. The total total input input to each each sing single le-p -pha hase se tran transf sfor orme merr unde underr thes thesee cond condit itio ions ns is therefore: Input
(2) × (69,00 (69,000 0 kVA) × (1.0 pf ) × (0.87) 3 transformers 40,020 kW
Transf Transform ormer er output output shall shall be based based upon upon the specif specified ied efficiency of 99.63 percent: Output 40,020 kW × (99. (99.63 63%) %)
B-14
4.00 kW
39,8 39,872 72 kW
$
) × (4.00
kW
kW
) 1/100% eff
$ 1/100% eff
Application of rates of evaluation evaluation to contract bid (3) Application and penalty for failure to meet guaranteed efficiency. The
calcul calculate ated d rate rate of evalua evaluatio tion n per 1/100 1/100 perce percent nt of transtransformer efficiency shall be used during the bid evaluation to credit the bid price for each 1/100 percent of efficiency that the guaranteed value exceeds the specified minimum value value of 99.63 99.63 percen percent. t. After After final testing testing of the transtransformer, twice the rate of evaluation shall be applied as a penalty for each 1/100 percent of efficiency less than the guaranteed value. Auxiliary cooling loss. loss. (4) Auxiliary
(a) Guide Specific Specification ation CE-2203 CE-2203 states states the following: following: In the evaluation of Transformer Auxiliary Power, the power required for motor-driven fans and oilcirculating pumps should be evaluated on the basis that each horsepower of motor rating in excess of the number of horsepower excluded from evaluation is equal in value to approximately 40 percent of the capitalized value of one kW of loss used in the transformer efficiency evaluation. (b) The rate rate of evalua evaluatio tion n for transfor transformer mer auxiliar auxiliary y power for FOA cooled transformers is given by: Rate of evaluation
$1,175 $1,175 × 40% 40%
$470 hp
EM 1110-2-3006 30 Jun 94 (c) The total horsepower of motor-driven fans and oil pumps pumps exclud excluded ed from from evalua evaluatio tion n for each each size size of transtransformer is given by: Total losses based on 99.6% estimated efficiency: 46,000 kVA 99.6%
46,000 kVA 184.74 kW
Total auxiliary loss in hp excluded from evaluation: 184.74 kW ×
.05 hp kW
9.24 hp
B-15
