Brush Turbo-generator (Alternator) Training Course

Turbogenerator Fundamentals November 6th2006

Brush Electrical Machines Ltd. PO Box 18, Loughborough, Leicestershire, LEI1 lHJ, England Telephone: +44 (1509) 61 1511 Telefax: +44 (1509) 610440 E-Mail: [email protected] Web Site: http:llwww.fki-et.com/bem

-BRUSH

B E M Ltd.-

I

I

Issue: A

I

I

Page: 2 of 5

TRAINING MANUAL CONTENTS 1 INTRODUCTION ........................................................................................................................................ 3 2 GUIDE TO TRAINING MANUAL ............................................................................................................... 3 3 PROJECT DOCUMENTATION ................................................................................................................. 3 4 TRAINING MODULES ............................................................................................................................... 4

ITraining Manual

CJBrush Electrical Machines Lld. 2006

I

INTRODUCTION This Training Manual is intended to provide Operators with an understanding of the concepts and procedures used in the design and manufacture of generators and ancillary equipment. In addition to general background information, the Training Manual incorporates details of basic design concepts and project specific information as appropriate. A schedule of the training modules provided, and a summary of their content is given in Section 4.

2

GUIDE TO TRAINING MANUAL Electronic copies of the Training Manual are provided in Adobe Acrobat format (PDF files), which includes bookmarks or links to enable the user to navigate between the various Sections within the manual. To move to the required Section, 'click' on the bookmark in the left hand portion of the screen.

3

PROJECT DOCUMENTATION The Training Manual is designed to supplement the information given in other project documentation Operating & Maintenance Manual comprising Installation 8 Commissioning procedures, Operation & Maintenance procedures, Drawings. Control & Monitoring Equipment and Suppliers Data. 9 Instruction ManualslHandbooks for Brush ancillary equipment 9 Quality Dossier incorporating as shipped equipment settings and, where B ~ s has h an involvement, as commissioned settings. 9

ITraining Manual

Q Brush E l e c t h l Machines Ltd. 2006

4

MODULES GENERAL Introduction To Brush Electrical Machines Ltd. Warning Symbols; Health & Safety At Work Act (1974); Control Of Substances Hazardous To Health (COSHH Regulations 1999); Operation & Maintenance; Protection & Monitoring Maintenance Philosophies Maintenance; Machine Deterioration; Maintenance Philosophies; Sensory Perception Principles Of AC Generation Faraday's Law Of Electromagnetic Induction; Three Phase Generation; Generator Excitation Control Systems GENERATORS DAX Generators Introduction; Stator; Rotor; Ventilation System; Bearings Open Ventilation Systems Internal Air Circuit; External Air Circuit Closed Air Water Cooling Systems Introduction; Maintenance; Pipework Systems Bearings -Fixed Profile Fixed Profile Bearings; Bearing Lubrication; Pressure Oil Seal Jacking Oil Panel Requirement For Jacking Oil; Jacking Oil Panel; Pipework Systems Generator EnclosurelCanopy

04 04.01. O l 04.02.01

04.03.01

(Training Manual

Generator Line And Neutral Cublcles Line Cubicles; Neutral Cubicles; Combined Line & Neutral Cubicles Generator Line Cublcles Generator Neutral Cubicles Generator Cleaning Cleaning A Seriously Contaminated Machine; Cleaning By Hand; COz Shot Blasting; Jet Water-Wash; Post Insulators Generator Rotor Removal Introduction; Precautions; Site Requirements; Rotor Removal Kit Components; Rotor Removal Procedure; Rotor Removal Illustrations; Rotor Threading Procedure; Rotor Transportation; Rotor Balancing GENERATOR INSTRUMENTATION Resistance Temperature Detectors And Thermocouples General; Recommended Alarm & Trip Settings; Resistance Temperature Detectors; Ovewoltage Protection; RTD Calibration Bently Nevada Vibration Monitoring Vibration Monitoring; Velocity & Acceleration Transducers; Measurements On Rotating Machinery GENERATOR SYSTEMS Power Generation Systems Prime MoverlGenerator; Generator . Operation; Automatic Voltage Control; Parallel Operation; Governor Droop; Generator Output Generator Synchronislng Introduction; DC Generators; AC Generators; Synchronising AC Generators; Lamp Synchronising; Synchroscope; Synchronising At The Switchboard/Control Panel; Automatic Synchronising; Check Synchronising; Closing Onto Dead Busbar Capability Diagrams Introduction; Stator Current; Power Output; Rotor Current; Stability Of The Rotor; Temporary Limitation; Use Of Capability Diagram; Capability Diagram For Synchronous Motor; Capability Diagram For Synchronous Condenser

O Brush Electrical Machines Ltd. 2006

Connection Of Generating Plant Introduction; G59 Recommendations Electrical Device Numbers 8 Functions Introduction; Device Numbers Equipment 8 Switchgear Labelling (853939) Introduction; General; Prefix Letter; Wire Numbers; Suffix Letters; Numbering Table High Voltage Phasing Checks Introduction; Phasing Out Of HV Systems; Phasing Sticks Electrical Power Resistance, Inductance & Capacitance; Current 8 Voltage; Active Power; Reactive Power; Power Factor & Apparent Power; Three Phase Power, Tariffs 8 Power Factor Correction. GENERATOR EXCITATION CONTROL EQUIPMENT Modular Automatic Voltage Regulator (MAVR) Principles The Brushless Generator; Generator Operation; Principles Of Automatic Voltage Control; Parallel Operation; The Generator Capability Diagram

-

ITralnlng Manual

0 Brush EWrlcal Machines Ltd 2006

INTRODUCTION -

-BRUSH

B E M Ltd.-

rraining Module: 01.01.01

I

Issue A

I

Date September 2002

0

.

..

Page. Iof 12

INTRODUCTION TO BRUSH ELECTRICAL MACHINES LTD.

l l . O l . O l (A) Introduction To BEM.doc

Q Brush Electrical Machines Ltd. 2002

1-

I

I

C INTRODUCTION TO BRUSH ELECTRICAL MACHINES LTD. -BRUSH B E M Ltd.Training Module: 01.01.01 1 Issue: A 1 Date: September 2002

. - .. I

Page: 2 of 12

CONTENTS 1 FKI PLC...................................................................................................................................................... 3 ........................................................................................................................... 3 1.1 Introduction........ ........................................................................................................ 3 1.2 FKI Energy Technology......... . . 1.3 Companies In The FKI Energy Technology Group ............................................................................. 4 2 BRUSH ELECTRICAL MACHINES LTD -HISTORY ......................................................................... 6 .............................................................................................6 Charles Francis Bmsh................... 2.1 Development ....................... ............................................................................................................ 6 2.2 2.3 Other Brush Products.......................................................................................................................... 7 2.4 Generators ........................................................................................................................................ 7 2.5 Diversification ...................................................................................................................................... 8 2.6 Development ..................................................................................................................................... 8 2.7 Brush Loughborough Site .................................................................................................................9 10 3 BRUSH ELECTRICAL MACHINES LTD introduction ............... . . . .................................................................................................................. 10 3.1 3.2 Products .........................................................................................................................................10 3.3 Industries Served ........................ . ................................................................................................11 3.4 Quality ............................................................................................................................................. 11 .. Aiter-Sales Service B Tralnlng ........................................................................................................11 3.5

. . .

..

. . . . .

.................................................................................................

01.01.01 (A) Introduction To BEM.doc

0 B ~ s Electrical h Machines Ltd. 2002

1

[-imm/

C INTRODUCTION TO BRUSH ELECTRICAL MACHINES LTD. -BRUSH B E M Ltd.Training Module: 01.01.01 I Issue: A I Date: September 2002 1

-. - . . I

Page: 3 of 12

FKI PLC Introduction

1.1

FKI plc is a major international engineering group. FKI has world leading positions in its specialised business areas of automated logistic solutions, lifting products and sewices, hardware and energy technology products. FKI was incorporated on 6 March 1920 in England under the companies Acts 1908 to 1917 and was re-registered on 3 June 1982 as a public limited company under the Companies Acts 1948 to 1980. The Group has operations in more than 30 countries and in the year ended 31 March 2002. its turnover amounted to f1.6 billion. and employs just under 16.000 people. b FKI Enerav Technoloqy

1.2

C

WKI PIC

I

I

-

I

C

I

L

.t)&~~ll+t.,, Lifting Products

Switchgear & Transformers Companies I HAWXI.

WRIC.. -A.7.

.SOD,.I,

110011c1 .OU"*l

<

Rotat~ngMachines Companies

I

I

!

r+$i - eri~torbbcock

-f

.Owl.

Baur.

Traction &Control Companies

SOYTW WALLS

* ,

-8RU6H

S E Y "a-

1.1,.

lndustrinl D r i w

*~(l

@ @a naf~\bFrn Trihnologr

WFroude Consine

WFroude liofmann

rn

-%I.Yd"

.UlcmmtD*L.m

@Mala(iMotori

FKI Electrical Engineering Group was established in 1996 following the acquisition of the Hawker Siddeley Electric Power Group and Marelli Motori. These acquisitions, added to the existing presence of Whipp & Bourne, Laurence Scott & Electromotors and Froude Consine within FKI, made up a Group of world class stature with synergies of technology, manufacturing, purchasing and sales. FKI Electri&l Engineering, along with the Measurement and Controls Division, formed FKI plc's Engineering Group. In July 2001, this became FKI Energy Technology.


O Bwsh Eklrical Machines Lld. 2002

-. - ...

pmim#q

@ INTRODUCTION TO BRUSH ELECTRICAL MACHlNES LTD. -BRUSH B E M Ltd.Training Module: 01.01.01 Issue: A 1 Date: September 2002

I

I

Page: 4 of 12

FKI Energy Technology is a leading independent supplier of rotating machines, particularly turbogenerators, switchgear and transformers; measurement and control products and is a significant supplier of other electrical products. Products and systems are sold to manufacturers of turbines, pumps, compressors, fans and other machines and to a wide variety of Customers in industry, power generation, oil and gas supply, air separation, petrochemical and contracting. Main businesses in the FKI Energy Technology group are: Rotating Machines: High, medium and low voltage electric motors; turbo, medium and low voltage generators; industrial drives, control equipment, frequency changers, engine and vehicle test systems. Switchgear: Indoor switchgear, outdoor circuit breakers, ring main units, pole mounted reciosers and DC switchgear. Transformers: Power, system and distribution transformers, pole mounted transformers and on load tap changers. Traction: Rail locomotive manufacture and refurbishment. Measurement and Control : Measurement and control devices and systems. b 1.3

Comoanies In The FKI Enerav Technoloav Grouo Many of the individual companies have histories going back over 100 years. These companies include: Brush Electrical Machines Ltd.: Located at Loughborough in the UK and is designated as FKl's Centre of Excellence for the design and manufacture of power management systems and air cooled 2-pole turbogenerators up to 150MVA. Brush HMA bv: The company, formerly known as 'HMA Power Systems' and before that 'Holec Machines and Apparaten', has been established for over 115 years and became part of FKI Energy Technology at the beginning of 2000. Brush HMA is FKl's Centre of Excellence for the design and manufacture of Cpole generators with ratings between 10MVA and 65MVA. Brush SEM sro: Located at Plzen in the Czech Republic and designated as FKl's Centre of Excellence for the design and manufacture of air cooled 2-pole turbogenerators above 150MVA, hydrogen cooled generators and hydrogenlwater cooled generators up to 1100MVA and the refurbishment of hydro generators up to 355MVA. Brush Transformers: Based in Loughborough, UK, Brush Transformers is a major international manufacturer of transformers. With over a century of experience, Brush Transformers manufacture a wide range of distribution, power, dry type, cast resin and traction transformers, along with flameproof transformers and switchgear. FKI Industrial Drives: Formed by the merger of Heenan Drives and Brush Industrial Controls, and now provide state of the art variable speed drive products from a new centrally located facility in Loughborough. Products also include AC sensorless flux vector inverters, synchronous motor drives and DC thyristor drives covering a power range from 0.37kW to 20MW. Fully engineered drive systems designed to customer specifications are available.. Hawker Siddeley Power Transformers: Based in Walthamstow. London, Hawker Siddeley Power Transformers is a major international manufacturer of power transformers including generator transformers for steam, hydro, nuclear and gas turbine power stations. Hawker Siddeley Switchgear: Based in Blackwood in South Wales, Hawker Siddeley Switchgear are an international producer of Switchgear. The Blackwood site is a centre of excellence for switchgear manufacture, producing a range of indoor and outdoor distribution switchgear.



Laurence Scott And Electromotors: Are the UK's premier manufacturer of electric motors (high and low voltage, ac and dc) and electro-mechanical power transmission product! (gearboxes, geared motors, eddy current variable speed drives, electro-pneumatic clutch/brakes). Brand names include LSE, NECO, EPG. TASC, NORAC. HEENAN. PSS GLENPHASE, EDC, SLENDAUR, CENTAUR. Marelli Motori: Produce a range of low and medium voltage asynchronous motors, DC motors and synchronous generators in a large variety of designs and power ranges up tc 3,000 kW. The factory is situated in Vicenza in the north of Italy, and has more than one hundred years of experience in the production of rotating electrical machines. South Wales Transformers: Based in Blackwood, South Wales, South Wales Transformer! is a major international manufacturer of distribution transformers and substations. Thr Blackwood site is a centre of excellence for distribution transformer manufacture, producing z wide range of liquid-filled distribution transformers, both pole- and ground-mounted, anc packaged substations. Whipp 8 Bourne: Established in 1903, and based in Rochdale. Lancashire, Whipp anc Bourne has long been a leader in heavy duty electrical switchgear. Products include a range of DC Circuit Breakers, Switchgear and Auto Reclosers. b



C TO BRUSH ELECTRICAL MACHINES LTD. issue A I Date September 2002 2

.

I

...

Page 6 of 12

BRUSH ELECTRICAL MACHINES LTD. -HISTORY 2.1

Charles Francis Brush

Figure 1: Charles Francis Brush The original company was the Anglo-American Brush Electric Light Corporation which was established in 1879 in Lambeth, London, to exploit the inventions of Charles Francis Brush (1849-1929). Brush, born in Cleveland, Ohio, had developed his first dynamo in 1876 and founded the American Brush Company in 1881. This American company lasted until about 1891. b

Lighting equipment (both arc lamps and incandescent lights) was the main product at first, expanding with the formation of lighting supply companies throughout the country. After an early boom in the promotion of lighting companies, the Electric Lighting Act of 1882 laid down new and onerous conditions of operating so that a general period of stagnation followed in the newiy-born electrical industry. However, there were some developments prior to the repeal of the Act in 1888, mainly in the field of industrial electrification. Thus the company was able to thrive on the manufacture of dynamos, motors, switchgear and small transformers. Trade again increased after 1888 and the works in Lambeth were no longer adequate for the vast increase in orders. New premises were required and, in the following year, the Falcon Engine and Car Works in Loughborough was purchased.

Figure 2: Brush Works (Early) 01.01.01 (A) lntmductionTo BEM.dcc


-

The title of the company was changed soon after the movement to Loughborough. At first, only the heavier manufacturing was transferred from Lambeth, but by 1895 most of the production was concentrated in the Falcon Works which by now incorporated large extensions. t

2.3

-

Other Brush Products

--

Figure 3: Brush 'Products' Prior to the First World War, tramcars and electrical engineering were the mainstays 01 production. The works employed about 2,000 men around 1910. Wartime, production was mainly concerned with munitions although vehicle bodies and even aircraft were constructed

t 2.4

Generators

Figure 4: 5000kW Brush-Ljungstrom Turbogenerator

I1 .O1 .O1 (A) Introduction To BEM.doc

c3 Brush Electrical Machines Ltd. 2W:

Electrical equipment sales remained steady during the period after World War 1. Turbine production experienced a great boom after 1918 when some 20 complete turbines with the attendant equipment were delivered each year. The size of these machines was in the 1.500 kW, 3,000 kW and 5,000 kW ranges, and they were well suited to the small municipal and company electricity works then in vogue. b 2.5

Diversification Employment in the works fell from a peak in 1925 when about 2,500 were employed to 1,500 some ten years later. The area of the works altered little. from 33 acres in 1924 to 35 acres in 1935 when the workshops covered about five acres. The first heavy oil engine made its appearance in 1935 and three years later in an attempt to diversify the range of products and to cater for an increasingly important line of business, the firm of Petters Ltd was taken over. Petters had been established in Yeovil. Somerset since the mid-19th century and had developed their first internal combustion engine in 1895. All the production was transferred to Falcon Works and remained there until 1948~whenthe former Lagonda Works at Staines, Middlesex were bought. After World War II the demand for heavy electrical equipment, dormant for many years. returned to the company making good the damage of wartime losses, and also encouraging renewal of large-scale capital investment in power generation. The new companies in the Brush Group were now more competitive in modern conditions and the two branches. ABOE (Associated British Oil Engines) and Brush, were complimentary in engine building and electrical equipment. Four-wheeled battery electric vehicles first appeared in 1947 and in the same year the Company returned to railway work after a lapse of many years, when diesel and diesel-electric locomotives were built in conjunction with W.G Bagnall Ltd of Stafford. Further companies joined the Group in 1950 when the National Gas & Oil Engine Company Ltd, Hopkinson Electric Company Ltd and the Vivian Diesels & Munitions Company Ltd of Canada were taken over. The title was changed to the "Brush ABOE Group'of Companies".

-

This was a period of great expansion with a large export drive and increasing capital investment in the industry. The £40 million of orders in 1951 were more than twice those of 1950. b

2.6

Develooment In April 1957 an offer of £22 million from the Hawker Siddeley Group was adopted and amalgamation took place. The Brush Group of companies was incorporated into the Hawker Siddeley Group under the name of Brush Electrical Engineering Co., Ltd. and had offices in Dukes Court, Duke Street, St James's, London S.W.1. In November 1991, the Hawker Siddeley Group was taken over by BTR plc in a f 1.5 billion bid. In the subsequent re-organisation Brush Electrical Machines Ltd became a major company within the BTR Electric Power Group, and the company's Traction Division became a separate company. Brush Traction Ltd. In November 1996, the FKI Group of Companies acquired the Hawker Siddeley Electric Power Group from BTR, Brush Electrical Machines and the other Brush companies joining the Group's Engineering Division. Following this, BrushTraction Ltd reverted to being a division of Brush Electrical Machines Ltd, and the Company's Industrial Controls Division became part of FKl's LSE Division. Brush Electrical Machines Ltd. is now one of FKI Energy Technology's Rotating Machines companies and is designated as the Centre of Excellence for the design and manufacture manufacture of power management systems and air cooled 2-pole turbogenerators up to 150MVA. Bmsh BEM joined with sister companies Brush HMA and Brush SEM to found the Brush Turbogenerators organisation. b

.Ol.Ol (A) Introduction To BEM.doc

@ Bmsh Electrical Machines Ltd. 2002

INTRODUCTION TO BRUSH ELECTRICAL MACHINES LTD. -BRUSH B E M Ltd.rraining Module: 01.01.01 I Issue: A I Date: September 2002 2.7

I

Page: 9 of 12

Brush Louahborouah Site

Figure 5: Brush Works, Loughborough In October 1960 the Falcon Works employed about 4,300 workers in the 40 acres ol workshops in a total site area of 59 acres. A majority of workers, 3.700, were employed or heavy electrical work whilst 500 were in the Traction Division and 100 on electric vehicle construction. The main production of the works still centred on electrical engineering witb heavy transformers, generators, motors, switchgear etc. In 1970 Hawker Siddeley Power Engineering, a project engineering group, was formed as a separate company with an office at a nearby site in Burton-on-the-Wolds and another at Chelmsford in Essex. Twelve months or so later, in 1971, the product divisions of the Brush Electrical Engineering Company Ltd were formed into separate manufacturing companies, Initially these comprised Brush Electrical Machines Limited, Brush Switchgear Ltd and Brush Transformers Limited, with Brush Switchgear taking on the responsibility of the Fusegea~ Division until January 1973 when Brush Fusegear Ltd was formally constituted. By this time there were approximately 5,000 workers on the Loughborough site. F


GI Brush Electrical Machines Ltd. 200;

-1

1

INTRODUCTION # TO BRUSH ELECTRICAL MACHINES LTD. Trainlng Module: 01.01.01 1 Issue: A 1 Date: September 2002 -BRUSH

3

B E M Ltd.-

.. . I

..I

Page:IOof12

BRUSH ELECTRICAL MACHINES LTD. 3.1

Introduction

-

BRUSH B E M Ltd.

-

Figure 6: Brush Electrical Machines Ltd. Logo Brush Electrical Machines Ltd. is now one of FKI Energy Technology's Rotating Machines companies and is designated as the Centre of Excellence for the design and manufacture manufacture of power management systems and air cooled 2-pole turbogenerators up to I50MVA. Brush BEM joined with sister companies Brush HMA and Brush SEM to found the Brush Turbogenerators organisation. Company turnover for the financial year 2001/2002 was approximately £90 million. Over 90% of production was exported. The company employs approximately 770 people. of whom 500 are in production. b

3.2

Products Our product portfolio, including relevant FKI Energy Technology products, includes: 9

9

9

9

9

9

CONTROLS PRlSMlC PMS power management systems for marine power and propulsion, offshore and onshore oil and gas applications, industrial and dockland installations. A range of automatic voltage regulators and excitation control equipment for generators and synchronous motors. GENERATORS Air cooled 2-pole turbogenerators for gas and steam turbine drive up to 200MVA, 15kV. Hydrogen and combined cooled 2-pole turbogenerators up to 1IOOMVA, 25kV. Air cooled 4-pole turbogenerators up to 65MVA, 15kV. Multi-pole synchronous types for diesel engine drive up to 30MVA, 15kV.. MOTORS Multi-pole synchronous single, multiple and variable speed types up to ZOMW, 15kV. 20-pole induction types up to 20MW, 15kV. LV cage induction types up to 1.5MW. DC types up to 120kW. Traction types up to 1000kW. Flameproof types. SWITCHGEAR Withdrawablelfixed vacuum circuit breakers, rated up to ISkV, 3150A, 40kA. Withdrawable fused vacuum contactors, rated up to 7.2kV, 400A, 40kA. TRANSFORMERS Distribution transformers 315kVA to 2500kVA. Power Transformers 2.5MA to 6OMVA up to 145kV. System transformers up to IEOMVA, 150kV. VARIABLE SPEED DRIVES . AC inverters up to 7MW, 1800V. AC synchroconverters up to 20MW. DC drive systems up to 3.5MW b

0 1 . O l . O l (A) Introduction To BEM.doc

-


1

6R\U;SH

B E M Ltd.Training Module: 01.01.01 -BRUSH

3.3

INTRODUCTION TO BRUSH ELECTRICAL MACHINES LTD.

I

Issue: A

I

I

-. - ..

fl

Date: September 2002

I

Page: 11 of 12

Industries Served Bmsh provides a complete electrical service to all sectors of the power industry. From a product portfolio encompassing generators, including control systems, for base load or intermittent duty, synchronous motors, power management systems and fully co-ordinated packages of electrical equipment. Brush can provide equipment and services to meet the most demanding specifications. Bmsh is renowned for the kind of robust yet versatile designs of generators and motors weli suited to the harsh operating environments encountered at oil and gas installations both onshore and offshore. This has led to Brush gaining an excellent reputation as a world class supplier to this demanding market. Brush also provides a complete electrical service to the marine industry. From generators and control systems, to complete electrical propulsion and auxiliary power system packages for naval, merchant and special purpose vessels. In addition, Bmsh can select and configure systems built from components sourced from throughout FKI Energy Technology group and elsewhere, including generators, motors, control systems, variable speed drives, switchgear and transformers, etc. h

3.4

Qualitv

I S 0 9001 Cem?icate No FM 12096

Figure 7: QA Registration Since 1991, the Company has been registered to IS0 9001 standard, which governs the quality of design, manufacture and service. Maintaining this registration, has become a cornerstone of management policy. All equipment complies with relevant European. American and International standard specifications. h 3.5

After-Sales Service 8 Training A comprehensive service is offered by the Service Department, located at Loughborough, dealing with the commissioning, service, repair and maintenance requirements on a worldwide basis. In addition, service centres in the USA, Malaysia. The Netherlands and Canada, along with local service partners in many other countries, can offer on-the-spot assistance. Comprehensive operator training courses for all products and systems are available either at the factory or at site. h

01.01.01 (A) IntroductionTo BEM.doc

0 Brush Electrical Machines Ltd. 2002

1

INTRODUCTION @ TO BRUSH ELECTRICAL MACHINES LTD. Training Module: 01.01.01 I Issue: A I Date: September 2002 -BRUSH

B E M Ltd.-

BLANK PAGE

-. . ... I

Page.lZofl2

SAFETY

SAFETY

31.02.01 (A) Safely.doc

O Brush Electrical Machines Ltd. 200:

SAFETY

M Ltd.Training Module: 01.02.01 -BRUSH

BE

I

Issue A

I

Date September 2002

Page 2 of 6

1 CONTENTS

....................................................................................................3 WARNING SYMBOLS ..................... . HEALTH 8 SAFETY AT WORK ACT (1974) ............................................................................................ 3 CONTROL OF SUBSTANCES HAZARDOUS TO HEALTH (COSHH REGULATIONS 1999) ............... 4

3.1 Introduction....................................................................................................................................... 4 .............................................. 5 3.2 COSHH Data For Standard Components ................................... . . OPERATION 8 MAINTENANCE ............................................................................................................... 6 PROTECTION AND MONITORING DEVICES..........................................................................................6

I

I

WARNING SYMBOLS Warning symbols used in manuals are as follows:

8

A A

Mandatory Notice - Instruction to be followed. Danger, General - Caution to be exercised. Appropriate safety measures to be taken, Danger. Electricity - Caution to be exercised. Appropriate safety measures to be taken Danger. Harmful or Irritating Substance measures to be taken.

+

2

-

Caution to be exercised. Appropriate safety

HEALTH (L SAFETY AT WORK ACT 119741 The information hereunder is supplied in accordance with Section 6 of the Health and Safety at Work Act 1974 with respect to the duties of manufacturers, designers and installers in providing health and safety information to Customers. The information advises of reasonably foreseeable risks involved with the safe installation, commissioning, operation, maintenance, dismantling, cleaning or repair of products supplied by Brush Electrical Machines Ltd.

I

I

Every precaution should be taken to minimise risk. When acted upon, the following precautions should considerably minimise the possibility of hazardous incidents. Delivery Checks: Check for damage sustained during transport. Damage to packing cases must be investigated in the presence of an Insurance Surveyor. Handling: Sling packing cases where indicated. Equipment not in a packing case, or removed from a packing case must only be lifled by the lifting points provided. Do not lifl complete machines by lugs on heat exchangers or air silencers etc. Storage: Unless the equipment has been designed for outside use or specifically packed for outside storage, store inside in a dry building, in line with the manufacturer's recommendations. Installation: Where installation is made by engineers other than Brush Electrical Machines Ltd. personnel, the equipment should be erected by suitably qualified personnel in accordance with relevant legislation, regulations and accepted rules of the industry. In particular, the recommendations contained in the regulations with regard to the earthing must be rigorously followed. Electrical Installation: IMPROPER USE OF ELECTRICAL EQUIPMENT IS HAZARDOUS.

A

It i s important to be aware that control unit terminals and components may be live t o line and supply voltages. Before working on a unit, switch off and isolate it and all other equipment within the confines of the same control cubicle. Check that all earth connections are sound. WARNING: Suitable signs should be prominently displayed, particularly on switches and isolators, and the necessary precautions taken to ensure that power is not inadvertently switched on to the equipment whist work is in progress, or is not yet completed.

01.02.01 (A) Salely.doc

0 Bwsh Electrical Machines Ltd. 2002

C SAFETY Training Module: 01.02.01

1

lssue: A

I


1

Page: 4 of 6

Adjustment and fault finding on live equipment must be by qualified and authorised personnel only, and should be in accordance with the following rules: D Read the Instruction Manual. D Use insulated meter probes. > Use an insulated screwdriver for potentiometer adjustment where a knob is not provided. > Wear non-conductingfootwear. D Do not attempt to modify wiring. > Replace all protective covers, guards, etc. on completion. Operation (L Maintenance: Engineers responsible for operation and maintenance of equipment should familiarise themselves with the information contained in the Operation & Maintenance Manual and with the recommendations given by manufacturers of associated equipment. They should be familiar also with the relevant regulations in force. 9 It is essential that all covers are in place and that all guards andlor safety fences to protect any exposed surfaces andlor pits are fitted before the machine is started. D Ail adjustments to the machine must be carried out whilst the machine is stationary and isolated from ail electrical supplies. Replace ail covers and/or safety fences before restarting the machine. 9 When maintenance is being carried out, suitable WARNING signs should be prominently displayed and the necessary precautions taken to ensure power is not inadvertently switched on to the equipment whilst work is in progress, or is not yet complete. D When power is restored to the equipment, personnel should not be allowed to work on auxiliary circuits, eg. Heaters, temperature detectors, current transformers etc.

I

Lifting Procedures: Ensure that the recommendations given in the manual are adhered to at all times.

3

I

CONTROL OF SUBSTANCES HAZARDOUS TO HEALTH lCOSHH REGULATIONS 1999) 3.1

Introduction The data provided hereafter satisfies the responsibilities detailed in the COSHH Regulations 1999, and includes details of substances commonly used on standard components supplied by Brush Electrical Machines Ltd. This data is not contract specific, and therefore may include substances not used Contract specific information can be obtained from our Service Department. ALWAYS USE SUBSTANCES IN ACCORDANCE WITH MANUFACTURERS INSTRUCTIONS. IF AFTER APPLYING THE SUGGESTED FIRST AID PROCEDURES, SYMPTOMS PERSIST, SEEK IMMEDIATE ADVICE FROM QUALIFIED MEDICAL STAFF. NEVER INDUCE VOMITTING, OR GIVE ANYTHING BY MOUTH TO AN UNCONSCIOUS PERSON.

01.02.01 (A) Safety.doc

(Q

B ~ s Electrical h Machines Ltd. 2002

I

4

OPERATION 8 MAINTENANCE

a

When working on this equipment it is important that a safe environment is achieved i.e 9 Isolate all electrical supplies including heaters. 9 Ensure adequate ventilation and lighting. 9 Use proper support for heavy items. 9 Maintain access ways. 9 Wear suitable protective clothing. Safety guards and covers must be fitted, unless the equipment has been made safe behind the guard or cover.

I

On-site safety procedures are to be followed as appropriate, in particular 'Permit To Work' type systems are be followed rigorously. Attention should be given to the advice given in Clause 2 (Health 8 Safety At Work Act (1974)) and Clause 3 (Control Of Substances Hazardous to Health (COSHH Regulations 1999)) Details of substances used on equipment that are potentially hazardous to health are detailed in Clause 3.2 and the Suppliers Data that forms part of the Operation & Maintenance Manual. IMPROPER USE OF ELECTRICAL EQUIPMENT IS HAZARDOUS. F

PROTECTION AND MONITORING DEVICES

A

WARNING: It is essential that any protection or monitoring device for use with generators or ancillary equipment should be connected and operational at all times unless specifically stated otherwise. It should not be assumed that all necessary protection and monitoring devices are supplied as part of Brush Electrical Machines Ltd. scope of supply. Unless otherwise agreed, it is the responsibility of others to verify the correct operation of all protection and monitoring equipment, whether supplied by Brush Electrical Machines Ltd. or not. It is necessary to provide a secure environment that ensures operator safety and limits potential damage to the generator and ancillary equipment. If requested, Brush Electrical Machines Ltd. would be pleased to provide advice on any specific protection application issues or concerns.

F

I

I

GENERATOR MAINTENANCE PHILOSOPHIES -BRUSH 8 E M Ltd.Date: September 2002 Training Module: 01.03.01 Issue: A

I

I

Page: 1 of 4

.

GENERATOR MAINTENANCE PHILOSOPHIES

01.03.01 (A) Generator Maintenance Philosophies.doc

D Brush Electrical Machines Ltd. 2002

1 --nuusti

BEM ~td.-

I


Training Module: 01.03.01

1

issue: A

CONTENTS 1 MAINTENANCE ........................................................................................................................... 3 2 MACHINE DETERIORATION ................................................................................................................... 3 3 MAINTENANCE PHILOSOPHIES ..................................... .................................................................. 3 3.1 Curative Maintenance 3 3.2 Preventive Maintenance 4 3.2.1 Time-Based Maintenan 4 3.2.2 Condition-Based Mainte 4 4 SENSORY PERCEPTION ...................................................................................................................... 4

.

1-1

-BRUSH

B E M Ltd.-

1



1

I

I

Issue A

I

1

rC

Date September 2002

Page 3 of 4

MAINTENANCE The term maintenance can be applied to a broad range of activities. in general, maintenance includes all activities necessary to enable the safe and efficient functioning of a machine or system, throughout its working life.

1

I

Maintenance can be said to encompass the following activities: 1) Maintain Proper Condition Prevent the malfunction of the machine or system. 2) Judge The Current Condition Obtain information of the actual condition of the machine or system. 3) Recondition To The Original Condition Maintenance must be performed to repair a fault.

Recommendations for the implementation of these activities are detailed in the Operating & Maintenance Manual, but the actual maintenance programme should be determined by the end user (or his representative) in order to reflect local site conditions e.g. operating regime, site location, operation B maintenance staff skills and availability, etc. b 2

MACHINE DETERIORATION The factors that cause machine deterioration include: 9 When Running 9 Outgoing Load 9 Thermal Load 9 Internal Magnetic Load 9 Internal Mechanical Load, including imbalance or misalignment. 9 External Mechanical Factors, including forces exerted by the prime mover, and external vibrations. 9 Ambient Conditions, including dust, water, corrosive atmospheres 9 At Standstill 9 External Mechanical Factors, including external vibrations. 9 Ambient Conditions, including dust, water, corrosive atmospheres From the above it can be concluded that the machine is 'subject to wear and tear' during its entire life. irrespective of the number of hours run. Any machine will therefore need to undergo a maintenance inspection or check from time to time. The purpose of this inspection is to detect possible abnormalities t operation, or in the case of a breakdown, determine the extent of that, sooner or later, may d i s ~ p its the damage. b

3

MAINTENANCE PHILOSOPHIES The availability of a machine has a direct influence on the wellbeing of a company. An unexpected breakdown can cause considerable inconvenience and financial loss. To keep a machine functioning efficiently throughout its working life can often cost more than the original cost of the machine itself, consequently the way in which maintenance is carried out is important. The objective is high reliability with minimum interruption of machine operation, with minimum outlay. There are two basic maintenance philosophies that can be adopted: b 3.1

Curative Malntenance With curative maintenance (or run-to-breakdown maintenance) a major overhaul is only performed after a breakdown. Overhauls cannot be planned and interruptions in operation occur unexpectedly. This policy is thus only appropriate when the machine's condition is likely to deteriorate abruptly, which is not usually the case with electrical machines. Certain components can, of course, always breakdown suddenly. b

01.03.01 (A) Generator Maintenance Philosophies.doc

I


1 3.2


1

C 'r 1

Preventive Maintenance With preventive maintenance, overhauls are planned ahead and take place in time to preven a breakdown. This means that the machine's condition should only be expected to deterioratt in a steady and predictable manner. For instance, the longer the machine is in operation the more likely the chance of a breakdown. In practice, particularly for electrical machines, preventive maintenance is preferred because i is more likely to ensure dependable plant operation. Preventive maintenance can be divided into two sub-categories, but in practice a combinatior of the two philosophies is used:

3.2.1

Time-Based Maintenance With time-based maintenance the machine is overhauled on the basis of calenda~ time andlor hours of operation e.g. once a month, year, etc. o r every so man) hours. In most cases this is acceptable, however there is the disadvantage that some components will be replaced before the are completely worn out. For example, thc bearing would still be functioning correctly.

3.2.2

Condltion-Based Maintenance With condition-based maintenance, the time when preventive action must bc undertaken is determined by the machine's condition. The assessment of the machine's condition must be carried out by means of monitoring equipment and skilled engineers who know how to interpret the measurements. b

SENSORY PERCEPTION Sensory perception means: P Looking P Touching P Smelling P Listening Sensory perception plays an Important part in maintenance, since it is often possible to detect abnormal behaviour or an abnormal situation at an early stage, without the use of any measuring equipment. b

I .03.01 (A) Generator Maintenance Philosophies.doc

O Bmsh Electrical Machines Ltd. 2W2

PRINCIPLES OF AC GENERATION -BRUSH

B E M Ltd.-


I

Issue: A

I


I

Page: 1 of 10

PRINCIPLES OF AC GENERATION

)1.04.01 (A) Principles Of AC Generation.doc

0 Bwsh Electrical Machines Ltd. 200:

- . .-----

-


B E M Ltd.-

rraining Module:

a

. -.

Date:

P a g e 2 of 10 --

:ONTENTS I ............................................. : FARADAY'S LAW OF ELECTROMAGNETIC INDUCTION ............... ! THREE PHASE GENERATION ................................................................................................................. ; I GENERATOR EXCITATION CONTROL SYSTEMS .............................................................................. f 3.1 Conventional Excitation System (DC Generator Commutator Exciter) t 3.2 Static Excitation System € 3.3 Brushless Excitation System E

. . .

.04.01 (A) Principles Of AC Generation.doc

O B ~ s Electrical h Machines Ltd. 2002


I

# 'm A

0

Motion

Figure I:Electromagnetic Induction Faraday's Law Of Electromagnetic Induction, illustrated in Figure 1, states that, if a conductor is moved in a magnetic field, then an electromotive force (emf) - or simply, a voltage - is induced in that conductor. it follows that, if the ends of the conductor are connected to an external load, then an electric current, driven by that voltage, will flow from the conductor, through the load and back again. Faraday showed that if a wire moves in a magnetic field, an artificial charge, or voltage, will be created in that wire. Faraday also showed that the magnitude of the voltage induced in the moving conductor depends on the strength of the magnetic field and the speed of movement, and on nothing else. These two laws form the whole basis of electrical power generation, both AC and DC. t Fleming's Right Hand Rule for generators determines how this is achieved. Figure '2 illustrates the relationship between the magnetic field (North to South), direction of motion and direction of emf (voltage) induced in the conductor.

Inducedemf Figure 2: Fleming's Right Hand Rule t

01.04.01 (A) Principles Of AC Generation.doc

O B ~ s Electrical h Machines Ltd. 2002

I

-BRUSH B E M Lid.Training Module: 01.04.01


I

Issue A

I

Date September 2002

Page 4 of 10

Figure 3 shows a loop of stiff wire on a shaft which can be turned. Suppose each end of the wire I connected to a slipring, insulated from the shaft, upon which there are brushes that are connected to load.

-

Figure 3: AC Generation Fixed Field As the shaft is turned, one bar passes the N-pole as the other passes the S-pole. Voltage is inducec one way in one bar and the opposite way in the other. b Figure 4 illustrates how an alternating curren waveform (sine wave) IS induced in the rotating coil as it passes the fx i ed magnetic field.

(a)

ELECTROMAGNETICINDUCTION

Figure 4: Alternating Current b

1 04 01 (A) Pnnc ples 01 AC Generatmn doc

.-

-

-.

-

Q Brush

Eleclncal Machines Lld 2&

Faraday's theory required only that the conductor should be moving through a magnetic field i.e. tha there should be relative motion between conductor and field. It would work just as well if the magnetic field moved past the conductor. In the arrangement shown in Figure 5 this is just what's happening.

Figure 5: Rotating Field (Permanent Magnet) In the above diagram, the stiff wire loop is fixed, and Me permanent magnet is rotated past it and inside it. As a pole passes a fixed conductor a maximum voltage is induced in it, opposite voltages on opposite sides, and they add up to give double voltage at the terminals or at the voltmeter.. In this arrangemenl no sliprings or brushes are needed which would be advantageous for a number of reasons, not leasl the reduced maintenance requirement. b

-

104 01 (A) Pnnclples 01AC Generation doc

--- ..

-- 0 Bwsh Eleclncal Machlnes Lld 2002

7I

1. n g o d u l e : 01.04.01 .. . -.

PRINCIPLED 0. AC GENERATION

I

I s s ~ eA:

I

-.. . .

.

1 jl(

.1 -

Date:September 2002

7

I

I

Page:.-6

So far only permanent magnets have been considered for producing the magnetic field. Far bette, results can be achieved by using an electromagnet, which can produce much stronger fields anc therefore much higher induced voltages (See Figure 6).

Figure 6: Rotating Field (Electromagnet) In this case however DC power must be provided to the coil which magnetises it. This can come from a battery or other DC source, but a pair of sliprings and brushes must be used to bring the battery currenl to the moving magnetising coil called the 'field coil'. This coil is said to 'excite' the field and the whole process is called 'excitation'.

-

Because the field magnet is not permanent but is an electromagnet, it is possible to vary the coil currenl by a resistance and so vary the strength of the magnetic field itself. This in turn will vary the amount ol the induced voltage. b Using this principle, it is possible for an Operator to control the machine's voltage (remotely) by varying the excitation. This is illustrated in the following diagram.

Figure 7: Voltage Control b

I .04.01 (A) Principles Of AC Generation.doc

0 Brush Electrical Machines Ltd. 2W2

2

THREE PHASE GENERATION

Figure 8: Three Phase Generation -Windings t The above diagram illustrates how the basic AC generator principles are applied to produce the three phase generation waveforms shown in Figure 9.

Figure 9: Three Phase Generation -Waveforms t

. 01 04.01 (A) P"nciples 01AC Generation aoc

. .-.

-. - .

0 Bwsn Electrical Machines Lta 200

1


3

*

r 4

GENERATOR EXCITATION CONTROL SYSTEMS Figure 7 showed how it would be possible (for an Operator) to control the main machine's voltage b) adjustment of the resistance which in turn varies the excitation i.e. If the Operator knows the voltage hc wants to see on a voltmeter connected to the generator output, he can adjust the resistance until the required value is achieved. This is called 'excitation control'. To make the process automatic, an electronic device called an Automatic Voltage Regulator (AVR) 01 Excitation Controller is used to sense the output voltage and compare it with a datum which has previously been set by hand. The AVR decides whether the output voltage is correct, too high or toc low. There commonly used types of excitation control systems for ac generators output control are: 3.1

Conventional Excitation Svstem fDC Generator Commutator Exciter)

-

Figure 10: Excitation System Conventional In this system, a dc control signal is fed from the excitation control to the stationary field of the dc exciter. The rotating element of the exciter then supplies a direct current to the field winding of the main ac generator. The rotating armature of the dc exciter is either driven from the same shaft as the rotating main field of the generator, or can be on a separate motor driven shaft. In both cases, a dc commutator is required on the exciter, and brushes and sliprings (collector rings) are required on the rotating generator field to carry the main generator field current. This system is sometimes used on smaller or older machines. b 3.2

Static Excitation Svstem

Figure 11: Static Excitatioh System

.04.01 (A) Principles Of AC Generat1on.doc

O Brush Electrical Machines Ltd. 2W2

ff PRINCIPLES OF AC GENERATION -BRUSH B E M Ltd.Training Module: 01.04.01

I

Issue: A

I


Page: 9 of 10

Static excitation systems obtain power from the electrical output of the generator or from the connected system to feed rectifiers in the regulating system, which in turn supply direct current to the main field winding of the generator through brushes and sliprings. b

3.3

Brushless Excitation System Brush generators are now almost exclusively fitted with 'brushless' excitation systems in which the exciter shares a common shaft thus doing away with the need for sliprings and brushes. Since a DC generator used as an exciter would require the brushgear to rotate, the main exciter is another, but smaller, AC generator with stationary field and rotating armature. The AC output from this armature is taken converted to DC through 'rectifiers' rotating with the shaft, and then fed to the rotating field winding of the main generator.

Sensing And

Main AC Exdter

Figure 12: Brushless Excitation System In this system the ac armature of the exciter, the rotating three phase diode bridge rectifier, and the main field of the ac generator are all mounted on the same rotating shaft system. All electrical connections are made along or through the centre of the shaft. b . It is common to add a small second, or 'pilot' exciter (or permanent magnet generator to excite the main exciter.

Pilot Exciter

- PMG)

Sensing

Main AC Exdter

Figure 13: Brushless Excitation s y s t e m w i t h Pilot Exciter b

01.04.01 (A) Principles OfAC

Generalion.doc



B E M Ltd.-


I

Issue A

I

Date September 2002

I

PagelOof10

Figure 14: Brushless Excitation System (Without Pilot Exciter) Some Customers prefer a brushless excitation system that does not use a pilot exciter. This arrangement is illustrated in the above diagram. b

01.04.01 (A) Principles Of AC Generation.doc


C DAX GENERATORS -BRUSH

B E M Ltd.-


I

Issue A

I

Date September 2002

Page 1 of 18

DAX GENERATORS

12.01.01 (A) DAX Generators.doc

@ Bmsh Electrical Machines Ltd. 2W:

1 1 d.-


1 ,-

DAX GENERATORS

I

issue: A

1

L


I

Page: 2 of 18

CONTENTS 1 INTRODUCTION ........................................................................................................................................ 3 .......................................................................................................... 1.1 Features .............................. . . 3 .................................................................................................. 3 1.2 Specifications .......................... . . . . ..................................................................................................... 1.3 Configurations ..................... . . . . 4 2 STATOR ..................................................................................................................................................... 5 2.1 Stator Frame ...................................................................................................................................... 5 . . . ...................................................................................................... 6 2.2 Stator Core ...................... . 2.3 Stator Winding ..................................................................................................................................... 7 2.3.1 Insulation System ................... ................................................................................................. 7 2.3.2 Coil Manufacture.......................................................................................................................... 8 2.3.3 Winding And Connections............................................................................................................ 9 ........................................................................................ 2.3.4 Winding Tests ............................... . . 9 2.4 Heaters.............................................................................................................................................. 10 3 ROTOR 11 3.1 Rotor Forging And Machining ........................................................................................................... 11 3.2 Rotor Winding................................................................................................................................. 12 3.3 Rotor Endcaps (Retaining Rings)....................................................................................................12 3.4 Rotor Earthing Brush.................................................................................................................... 13 3.5 Rotating Rectifier Assembly ............................................................................................................13 3.6 Rotor Tests ................................................................... ................................................................ 14 I VENTILATION SYSTEM 16 4.1 Internal Air Circuit.............................................................................................................................. 16 4.2 Stator ................................................................................................................................................. 16 17 4.3 Rotor.................................................................................................................................................. 5 BEARINGS 18 5.1 Bearings ............................................................................................................................................18 5.2 Monitoring Equipment .................... ..............................................................................................18

. .

.....................................................................................................................................................

. .

. .

........................................................................................................................

............................................................................................................................................

. .

2.01.01 (A) DAX Generatan.doc


DAX GENERATORS -BRUSH

B E M Ltd.-

Training Module: 02.01.01 1

I

I

Issue A

I

Date September 2002

Page 3 o f 18

I

INTRODUCTION

I

Figure 1: DAX Type Generator

' I. I

Features Wide experience gained from the long established Brush 'DAX range of air cooled, two pole, cylindrical rotor turbogenerators has provided the following features: 9 Simple foundation design for economic and speedy civil work. > Minimum number of individual power station components, offering substantial savings on expensive site time. % All units are fully factory tested, reducing commissioning to proving interconnections and combined turbinelgenerator testing. > Modular construction giving a fine balance between design flexibility and standardisation of components for fast economic production. 9 Fully developed system readily adapted to any turbine design. 9 Endframe or pedestal bearing machines available for all ratings. b

1.2

Specifications The DAX range of turbogenerators fully complies with the provisions of the relevant British. American and International Standard Specifications. The more common standards are: 9 BS 5000 Part 2 P IEC 34.1 and 34.3 > ANSl C50.13 (Steam Turbine Drive) 9 ANSl C50.13 (Gas Turbine Drive) b

02.01.01 (A) DAX Generaton.doc



B E M Ltd.-

Training Module: 02.01.01 1.3

I

Issue A

1

Date September 2002

Page 4 of 18

Confiaurations In order to accommodate various turbinelgenerator arrangements, a variety of generator driv, configurations are available which include:

-

Figure 2: Single End Direct Drive Endframe Bearings

-

Figure 3: Double End Direct Drive Endframe Bearings For information, DAX generators complete with basepiate, gearbox(es) and clutch(es) can also be provided.

-

Figure 4: Single End Drive With Baseplate, Gearbox And Clutch Pedestal Bearings b

.-

02 01 01 (A) D M Generalon aoc

-

. -

-

@'Brush Eleclncal Machlnes Ltd 2002


B E M Ltd.-

rralnlng Module: 02.01.01 ?

I

Issue A

I

Date September 2002

Page 5of 18

STATOR 2.1

Stator Frame

Figure 5: Stator Frame The stator frame is fabricated from mild steel plate, forming a rigid structure. Stators for endframe bearing generators have substantial mounting pads at suitable points on the underside. Holes are provided in each pad for foundation bolts and dowels. F Afler the fabrication process is complete, the stator frame is machined concentric throughout.

Figure 6: Stator Frame Machining For Concentricity All end faces are machined at the same time to ensure correct mechanical alignment during assembly. b

- -12 01 01 (A) DAX Generalon aoc

--

--

. O Blush Eleclncal Mach nes Lld 2Wi

r6RUSH1 -BRUSH

B E M Ltd.-

Training Module: 02.01.01 2.2

DAXGENERATORS

I

Issue A

I

I 'r

c

Date September 2002

-

..

Page 6 of 18

Stator Core

Figure 7: Stator Core Build The core is built up from segmental laminations of low-loss, high permeability, high silicon content electrical steel. The laminations of the core are located by means of dovetail key bars, bolted to suitably placed members of the stator frame. All laminations are deburred and coated with insulating varnish to minihise interlaminar contact and restrict eddy current losses. Radial ventilation ducts are formed at intervals along the core by 'H' section steel spacers. On each side of the spacer is a thicker lamination to prevent core distortion. The spacers extend to the end of the slot teeth to increase tooth rigidity. The core is hydraulically pressed at predetermined stages during the building operation to ensure uniform compaction, the pressure being carefully monitored. The finished core is cramped between heavy steel end plates which are located by keys inserted in slots in the key bar lands whilst the core is under pressure. Substantial nonmagnetic tooth supports transmit the pressure from the endplates to the stator teeth. On large units the end plate and tooth supports are formed in a single integral cast unit using nonmagnetic alloy. The core is subjected to a magnetising test prior to the insertion of the winding to check for soundness of interlaminar insulation and adequate tightness. b

'.01.01 (A) DAX Generaton.doc


DAX GENERATORS

2.3

I hI

Stator Windinq The stator winding is of the two layer diamond type, half coils being used for ease of handling during manufacture and winding. To satisfy the electrical design requirements, the winding may be of the single or multiple conductor type with parallel connections where necessary. In order to minimise eddy current losses, each conductor is subdivided into appropriately sized laminations which are insulated from each other by a resin impregnated woven glass braid and fully transposed to minimise circulating currents. Transpositions of the endwinding or Roebel type are used as appropriate.

Figure 8: Roebel Method Of Conductor Transposition The former transposes one or more laminations at each coil nose, the connection being arranged so that, over the complete winding, a complete transposition is achieved. This is particularly suited to multi-turn coils. On large single turn coils, it is not possible to match the number of laminations with the total number of turns per phase, and a Roebel system of transposition within the slot is used. b 2.3.1

Insulation System The insulation system is based on a resin rich mica glass tape which, when processed, results in a high performance insulation capable of continuous operation at temperatures up to 155% (Class F). The insulation possesses high dielectric strength and low internal loss and can meet all current specifications. The resin system is thermosetting so that the resulting insulated coil sides are dimensionally stable. Additionally, it is highly resistant to most of the common electrical machine contaminants such as hydrocarbons, acids, alkalis and tropical moulds.

? . O l . O l (A) DAX Generaton.doc

@ Brush Electrical Machines Ltd. 2002

DAXGENERATORS -BRUSH

B E M Ltd.-


I

1

Issue: A

I

C


Page' 8 of 18

Coil Manufacture

2.3.2

I

I

Figure 9: Stator Coil Construction (Simplified) The insulated copper laminations are cut to length, stacked together and the coil ends formed into the required endwinding shape on a jig. They are then clamped tightly together, taped with an initial layer of tape and hot pressed to consolidate the conductor stack. Following this, the main insulation is applied and pressed to size. The amount of the compression is carefully controlled to ensure correct resin flow and produce a consistent high standard of void free insulation.

Flgure 10: Stator Coils Each finished half coil is subjected to dimensional checks to ensure a correct fit in the stator slot is achieved. To prevent corona discharge in the slot and resultant insulation damage, the surface of the coil in contact with the core is made conductive by the application of a graphite impregnated polyester tape. A silicon carbide impregnated polyester tape is applied to the coil surface immediately outside the slot to control the voltage gradient in this region. b



I


B E M Ltd.-

Training Module: 02.01.01 2.3.3

1

Issue A

I

Date September 2002

Page 9 0 f 18

Winding And Connections The half coils are placed in the stator slots in two layers and wedged securely in position by synthetic resin bonded wedges prior to connection of the endwinding.

Figure 11: Inserting Wedges To Retain Stator Winding In Slots In order to withstand the forces which could arise in the event of an accidental short-circuit, the endwinding is security braced to insulated brackets supported from the stator frame. Spacer blocks are fitted between adjacent coil sides to produce a strong arch-bound, yet resilient, composite structure.

Figure 12: Stator Endwlnding Finally, the completed stator is 'baked' in an oven to fully cure the insulation. Resistance temperature detectors and thermocouples are embedded in tht windings at selected points, and anti-condensation heaters are fitted into the Stat0 frame. 2.3.4

Winding Tests Graded high voltage tests are carried out at stages during manufacture of the coil: and assembly of the winding. This ensures a high standard of insulation and alsl that any faults are detected at the earliest possible stage. F


0 Brush Electrical Machines Ltd. 2W


B E M Lid.-


I

Issue: A

1


I

Page:IOof18

Heaters are located in the generator and exciter frames. The purpose of the heaters is to prevent moisture condensation on the windings and metal parts, which could lead to low insulation resistance or corrosion. Access plates to the generator heaters, mounted at the ends of the stator, are provided. Exciter heaters mounted between poles at the bottom of the exciters, are accessible by removing the exciter endframe. Prior to energising the heaters, normal safety precautions should be adopted. When the heaters are energised, it is advisable to leave a small gap (say 5mm) behind some of the access covers to allow warmed air to be replaced by cool air, thus maintaining dry air inside the machine. Rain, dust, rodents, etc. should not be allowed to enter via this gap.

A

WARNING: Before energising the heaters, ensure that there ale no flammable materials in their vicinity.

The heaters should always be energised when the machine is not in service. p

02.01.01 (A) D M Generators.doc


I

DAX GENERATORS

3.1

L

H

Rotor Forqina And Machininq The rotor is manufactured from an integral forging of nickel chromium molybdenum alloy steel which is de-gassed and vacuum poured to obtain a uniform material which has excellent tensile properties. The manufacture of the forging is closely supervised with the forgemaster to an agreed quality control procedure, including checks for freedom from porosity and for mechanical and thermal stability. The standard forging material is suitable for use in ambient temperatures down to minus 20'C. In situations where the rotor may be subjected to lower temperatures, special materials are available. Axial slots, to cany the winding and for ventilation, are milled on the periphery of the body of the rotor.

Figure 14: Rotor Slot Machining Axial grooves are milled along the top of both winding and ventilation slots to hold the slot closing wedges. At the exciter end, a hole is bored along the axis of the shaft to take the leads from the main exciter to the rotor field winding. The connections to the rotor winding are brought out from the bore by radial connections. b


O Bmsh Electrical Machines Ltd. 2WZ


B E M Ltd.-


1

3.2

I

Issue: A

I


I

Page:12of18

Rotor Windinq The rotor winding conductor material is high conductivity copper silver alloy strip. The preformed coils are inserted into the slots, each turn being insulated from the next. Th class 'F'insulation system is moisture resistant, shockproof and capable of withstanding th high mechanical forces to which it will be subjected.

I

1 I

I

Figure 15: Wound Rotor, 3.3

Rotor Endcaps (Retaininn Rinasl After completion of the winding, the conductors are heated electrically and pressed to tht correct depth using pressing rings. A fully interconnected damper winding is fitted into the tops of the slots and the retainin5 wedges are inserted. The rotor endwinding is braced with packing blocks between the conductors, after which the rotor endcaps are fitted. The endcaps, which retain the rotor end. winding are manufactured from austenitic nonmagnetic 18-18 manganese chromium stee which is cold expanded during manufacture to produce the high mechanical strength required.

Figure 16: Rotor End Caps The endcaps are shrink fitted to spigots at each end of the rotor body.

I

Figure 17: Rotor End Caps (Fltted) b 02.01.01 (A) DAX Generators.doc


-

BRUSH1

-BRUSH

B E M Ltd.-

I

rraining Module: 02.01.01 3.4

DAX GENERATORS

I

Issue: A

I


I

Page 13of18

Rotor Earthinq Brush Current flowing across the oil film in a bearing can lead to the destruction of the by arc erosion in a comparatively short time. To overcome this problem a carbon rotor shaft earthing brush is fitted. The standard rotor earthing brush is approximately 25mm x 12.5mm x 40mm long, and should be changed when it has worn to approximately 14mm long.

Figure 18: Rotor Earthing Brush Standard DAX generators have both bearings insulated. The (main) exciter end bearing earth link wire should be left disconnected (bearing bush insulated) and the non-(main)-exciter end bearing earth link connected (bearing bush uninsulated). b 3.5

Rotating Rectifier Assembly

Figure 19: Rotating Rectifier Assembly (With REFM Transmitter) Brush generators are now almost exclusively fitted with 'brushiess' excitation systems in which the exciter shares a common shafl thus doing away with the need for sliprings and brushes. Since a DC generator used as an exciter would require the brushgear to rotate, the main exciter is another, but smaller. AC generator with stationary field and rotating armature. The AC output from this armature is taken converted to DC through 'rectifiers' rotating with the shaft, and then fed to the rotating field winding of the main generator. In this system the ac armature of the exciter, the rotating three phase diode bridge rectifier. and the main field of the ac generator are ail mounted on the same rotating shaft system. All electrical connections are made along or through the centre of the shaft

12.01.01 (A) DAX Generalon.doc


-

(~Ru-BRUSH

B E M Ltd.-

1


DAX GENERATORS

I

Issue: A

I

@

1


I

Page:14of18

The risk of diode failure is very remote. However, if a diode does break down, a heavy revers€ current will flow which is interrupted by the fuse. The adjacent diode and fuse would then be called upon to carry the whole current that was previously divided between two parallel paths Each path is designed with sufficient surplus capacity to carry the full current continuously The generator will therefore continue running as if nothing had happened. If the more heavily loaded diode should subsequently fail, its fuse will blow, thus isolating the faulty arm completely. Again the generator can continue operating, but in this case a ripple is induced in the exciter field current which is detected by the diode failure indicator unit. In this event, the set should be shutdown at the earliest opportunity so that the failed diodes and blown fuses can be located and replaced as follows: Locate blown diodes and fuses using a low voltage continuity checker. It may be necessary tc separate the diodes and fuses to do this. Always replace both the blown fuse and the associated diode even if one is apparently healthy. Re-assemble any diodes that have been replaced or disturbed, ensuring proper contact with the heat sinks. Refer to the instructions on the drawings. Good joints are essent1ai.b 3.6

Rotor Tests

Figure 20: Overspeed Test Pit All completed rotors are tested in the Company's rotor overspeed test facility, which is equipped with comprehensive monitoring equipment. The rotor is first given a low speed balance and is oversped to 20% above its normal operating speed for two minutes. The rotor is then heated to its maximum operating temperature, check balanced and the overspeed test is repeated. Finally, the balance at normal running speed is checked.

.01.01 (A) D M Generaton.doc

63 B ~ s ElecVical h Machines Ltd. 2W2

C DAX GENERATORS -BRUSH

B E M Ltd.-


I

Issue: A

I


I

Page:15of18

Balance adjustment planes are provided in the rotor body itself, in the ventilating fan rings, in special balance rings, and in the main exciter diode carrier fan hub. owing overspeed testing. the rotor is subjected to high voltage tests to prove the integrity of the insulation system. t

02.01.01(A) DAX Generaton.doc


- . . ...


B E M Ltd.-


Issue: A

I


I

Page:16of18

VENTILATION SYSTEM 4.1

Internal Air Circuit

Figure 22: DAX Generator Cooling air is forced around the generator by means of two axial flow fans mounted on the rotor shaft. b 4.2

Stator

I

Figure 23: Basic Ventilation System The stator core has radial ventilating ducts at intervals along the core. Most DAX units are too long for the stator cooling air requirements to be supplied by simple air gap flow, and this is overcome by arranging radial inward flow of air over sections of the stator to provide adequate airflow over the entire core length. In this case, the space behind the stator core is divided into five compartments. The first, third and fifth compartments are open at the top, forming the air exhaust flange. The second and fourth compartments are sealed at the outside, but are connected to the stator endwinding compartments by ducts through which they are fed with cool air in parallel with the airgap. b 02.01 .O1 (A) DAX Generaton.doc

@Brush Electrical Machines Lld. 2002

I

., .

DAX GENERATORS

-BRUSH B E M Lid.Training Module: 02.01.01

1

4.3

I

Issue: A

I


1

.a.

Page:17of18

Rotor The rotor is cooled by air flowing under the rotor endcap, past the endwinding and through axial cooling slots (interslots) between the winding slots.

Figure 24: Rotor Ventilation With lnterslot Cooling Only Exhaust ducts in the closing wedges of the interslots allow the air to escape at the centre 01 the rotor. In addition to the interslots, the rotors of larger machines also incorporate cooling slots (subslots) beneath the winding slots. The cooling air escapes from the subslots through radia exhaust ducts along the length of the winding.

-

Figure 25: Rotor Ventilation With Subslot.And Interslot Cooling Rotors with subslot cooling have independent cooling air paths over the endwinding tc minimise the temperature gradient across the winding. b

--02 01 01 (A) DMGenerators doc

--

--0 Brush Electrical Machlnes LtO 200


B E M Ltd.-


I

Issue: A

I


I

Page:IBof18

BEARINGS 5.1

Bearinas Various types of bearing, including fixed profile and tilting pad, are used depending on the application.

I

Figure 26: Endframe Bearlng Endframe bearing generators have specially stiffened and reinforced stator frames. A detachable solid ribbed steel plate, split on the bearing horizontal centreline incorporates the lower half bearing housing. The upper bearing housing is bolted and doweled to the bottom half housing. The endframe is completed by a steel plate bolted'on as the upper part of the endplate. This is arranged in sections capable of easy removal to give access to the bearing. t 5.2

Monitorinq Eaui~ment Provision is made on all bearings for temperature detectors in the bearing metal and in the oil drain. Most types of vibration detector can be accommodated. t



OPEN VENTILATION SYSTEMS -BRUSH

B E M Ltd.-


I

Issue A

I

Date September 2002

Page 1 of 6

OPEN VENTILATION SYSTEMS

02.02.02 (A) Open Ventilationdoc

Q Brush Electrical Machines Ltd. 2 W 3

.


B E M Ltd.-


I

Issue A

I

Date September 2002

Page 2 of 6

CONTENTS 1 INTERNAL AIR CIRCUIT .........................................................................................................................3 1.1 Stator .................................

......................................................................................................................... 5 2.3 2.4

Filter Type Maintenance........... . ..........

. . ......................................................................................................

6

II 1


I

*

B

3

INTERNAL AIR CIRCUIT

DAX turbogenerators are cooled by air, either in open circuit, filter ventilated, or closed air circuit water cooled configuration.

I

I

I

The generator internal air system is similar in all cases. Cooling air is forced around the generator by means of two axial flow fans mounted on the rotor shaft.

Flgure I: Basic Ventilation System The stator core has radial ventilating ducts at intervals along the core. Most DAX units are too long for the stator cooling air requirements to be supplied by simple air gap flow, and this is overcome by arranging radial inward flow of air over sections of the stator to provide adequate aifflow over the entire core length. In this case, the space behind the stator core is divided into five compartments. The first, third and fifth compartments are open at the top, forming the air exhaust flange. The second and fourth compartments are sealed at the outside, but are connected to the stator endwinding compartments by ducts through which they are fed with cool air in parallel with the airgap

02.02.02 ( A )Open Ventilation.doc


I


B E M Ltd.-


I

I

Issue: A

I

ff


Page: 4 of 6

The rotor is cooled by air flowing under the rotor endcap, past the endwinding and througi axial cooling slots (interslots) between the winding slots.

Figure 2: Rotor Ventilation With lnterslot Cooling Only Exhaust ducts in the closing wedges of the interslots allow the air to escape at the centre oi the rotor. In addition to the interslots, the rotors of larger machines also incorporate cooling slots (subslots) beneath the winding slots. The cooling air escapes from the subslots through radial exhaust ducts along the length of the winding.

I

I

Figure 3: Rotor Ventilation With Subslot And lnterslot Cooling Rotors with subslot cooling have independent cooling air paths over the endwinding to minimise the temperature gradient across the winding.

02.02.02 (A) Open Ventilation.doc


IBRUSHI -BRUSH

1

I

B E M Ltd.-

I


C - a

Date: September 2002 2

*..

Page: 5 of 6

EXTERNAL AIR CIRCUIT Open ventilated generators are cooled by ambient air drawn into the machine through filters and exhausted through an outlet duct connected to the stator air outlet flange.

Figure 4: External Air Clrcuits 2.1

Indoor Units Indoor units usually have the inlet filter mounted in the wall of the power station building, the filtered air being ducted to the generator air inlet flanges. The hot exhaust air is ducted from the generator to the outside of the building. Air silencers are fitted into the inlet and exhaust ducts. The silencers are of the splitter type and are constructed from heavy gauge galvanised steel with a sound absorbing infil which is non-hygroscopic, vermin proof and non combustible.

2.2

Outdoor Units Outdoor packaged units have the inlet filters supported in racks in the enclosure walls or housed in a separate air treatment module, which can be mounted above or beside the generator package. The exhaust air is ducted through the roof of the enclosure or through the air treatmenl module. Stainless steel gravity closing louvres at the outlet inhibit the ingress of rain or snow whilst the machine is shut down. The inlet and exhaust silencers are incorporated in the enclosure or the air treatment module.

2.3

Filter Tvues Replaceable media filter pads or washable filter bags, protected on the outside by angled louvres, are suitable for most environments. However, certain severe climatic conditions require additional filtration or slight modifications to.the . air circuit. Inertial separators can be fitted on the air inlets to remove excessive sand or large dusl particles. in marine environments, coalescer filters can be used to remove salt laden moisture droplets. In areas subjected to heavy rainfall, hoods are fitted to protect the air inlets and, if necessary, the exhaust. ---- -. -..- .

02 02 02 (A) Open Ventilation doc

--

- -.-. GI &sh

-

Electrical Machines Lta 2003

I

1- [

-BRUSH

B E M Ltd.-

I



I

Issue: A

I

1i-C


.. ... Page: 6 of 6

In drifting snow or freezing fog, there is a danger of filter blockage. To overcome this, a temperature sensitive, motor operated recirculation system located in the inlet hood recirculates some of the hot exhaust air over the inlet filters. Where extended filter life is desirable, self cleaning filters of the 'pulse clean' type can be provided. These are housed in a free standing module connected to the generator air inlets. 2.4

Maintenance Generator air intake filters must be properly maintained so that the total pressure drop external to the generator taking into account all ducting, filters (maximum dirty pressure drop), silencers, louvres etc., at the inlet and outlet, must not exceed the specified system design pressure drop. A differential pressure switch is usually connected across the filters to give a signal to notify

the Operator when filter renewal is necessary.

02.02.02(A)Open Ventilation.doc

~.

@Brush Electrical Machines Ltd. 2003

--

-- -- -

SH] I

--- -

--F ; 1

- 1

CLOSED AIR WATER COOLING -SYSTEMS

CLOSED AIR WATER COOLING SYSTEMS

12.02.03(13)CACW Coolin~.doc

@Brush Electrical Machines Ltd. 200:

:ONTENTS I INTRODUCTION........................................................................................................................................? ! MAINTENANCE ......................................................................................................................................... I I PIPEWORK SYSTEMS .............................................................................................................................. I

x 0 3 (8) CACW Cooling aoc

-B B n s h Eleclncal Machlnes Ltd 2W:

-1

-BRUSH

B E M Ltd.-

1



/

1

I

Issue: B

I

I Page: 3 of 6

Date: October 2002

I

INTRODUCTION Site conditions, such as severe desert conditions, extremely salty atmosphere or unsuitably contaminated environments may necessitate the use of a closed air circuit machine. Hot exhaust air from the generator is cooled before being returned to the generator inlet. Cooling is accomplished by means of water cooled heat exchangers containing tube nests which are arranged to permit cleaning in situ, but which can be easily removed for maintenance if required.

Figure 1: Airflow TolFrom Top Mounted Heat Exchanger I

, F-LO1-114

/ qra-M.

. -mar. ,YI_*-d,&,-w

--*--*-.wb.&.w

, . . L I -.--#-

-.=*-

c--**-"--\,~

amR-.Mmd-S

b-,--.

Flgure 2: Heat Exchanger Construction b

02.02.03 (6) CACW Cooling.doc

O Brush Eleclrical Machines Ltd. 2002

-BRUSH

B E M Ltd.-

1



I

Issue: B

I

1*

Date: October 2002

Page: 4 of 6

The heat exchanger is usually mounted in a sheet steel housing on top of the machine but the desigr and position of the heat exchanger assembly can be arranged to suit any specific application. The heat exchanger tube nests are complete with flanges for connection to the water supply, and arc arranged to permit part load operation with one or more tube nests inoperative.

Figure 3: Typical Top Mounted Heat Exchanger Generators fitted with multi-section coolers can be operated at reduced load (generally 67%) with one cooler section isolated for maintenance. Care should be taken not to operate the generator with two, series connected, tube nests inoperative. The cooler is designed to provide long and efficient service at the specified water flow rate. Reduction of water flow rate through the cooler, even if the generator is operating at part load, is no1 recommended, since low water velocity may result in tube blockage. On units fitted with emergency doors, the generator may be operated on open-air circuit for a limited time in the event of water circulation failure. In these circumstances ALL emergency doors in the cooler and enclosure are to be open to ensure maximum air flow. If doors are opened with the generator running, outlet doors should be opened first. t Water leaks from the heat exchanger into the generator are extremely rare. Those leaks as do Occur are invariably 'weeping' leaks at the joint between heat exchanger tubes and tubeplates. To ensure that any water released by a 'weeping' leak cannot be carried into the generator by the cooling air stream, it is usual for the 'top mounted' cooler design incorporate tube end spray baffles on each cooler nest. In addition, the tubes nests are located in deep drip trays which are drained through leak detectors.

Figure 4: Water Leak Detectors t

!.02.03(B) CACW Coolingdoc

D Brush E l ~ t r i c aMachines l Lld. 2002

I

2

I I

I

MAINTENANCE The system should be bled of air every month, or as experience dictates, to ensure that trapped air does not accumulate in the system. It is recommended that tube bores should be inspected, by removing water boxes, at the following intervals: Sea Water: Fresh Water: WaterIGlycol:

2 years 3 years 5 years

Care is required to ensure that the n ifs are not damaged during the cleaning process. Normal precautions to prevent ground contamination, drain contamination and vapour build-up should be observed.

I

The make-up air filter should be cleaned every 12 months. The filter should allowed to dry before refitting, ensuring that air gaps (leakage) between the filter and frame are minimised. It is necessary to lealdpressure test a cooler on site only when a cooler leak is suspected and cannot be located by other means or whenever header boxes have been removed and it is desired to check the re-sealing.

A

WARNING: During testing, any pressure above the Design Static Pressure, even for a short period, can cause severe damage and must be reported.

If, following testing, the vent valve is closed too early during the fill cycle, and a measurable pressure has been established then the cooler may not be properly vented. It will be necessary to vent the cooler back down to atmospheric pressure again before finally closing the vent valve.

3

PIPEWORK SYSTEMS To prevent leaks, it is important to check the tightness of connections in pipework systems particularly following installation, maintenance and overhaul operations.

02.02.03 ( 6 )CACW Cooling.doc


1

-BRUSH

B E M Ltd.-

1



I

Issue: B

I

I

rC,

Date: October 2002

Page: 6 of 6

BLANK PAGE

02.02.03(6) CACW Cooling.doc

D Brush Elect"cal Machines Ltd. 2002

-

BEARINGS FIXED PROFILE -BRUSH

B E M Ltd.-

1


I

Issue: A


Page: 1 of 4

-

BEARINGS FIXED PROFILE

I

I point of contacl at rlandstill equilibrium point st n rev.lmin

02.03.02 (A)Bearings - Fixed Profile.doc

2 O Brush Electrical Machines Ltd. 2W: -

BEARINGS -FIXED PROFILE

B E M Ltd.Training Module: 02.03.02

-BRUSH

I

Issue A

1

Ir

Date September 2002

Page 2 of 4

CONTENTS

1

I FIXED PROFILE BEARINGS ............................................................................................. BEARING LUBRICATION ................................... ....................................................................................................4 PRESSURE OIL SEAL .............................................................................................................................. 41 3 2

~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~

FIXED PROFILE BEARINGS

I

Figure 1: Fixed Profile Bearlng The spherically seated, forged steel bearing bushes are split on the horizontal centre line for ease of inspection and removal. The two halves are bolted and doweled together. Fixed profile bearings can have a spherical or elliptical profile depending on the application. 2

BEARING LUBRICATION Oil is supplied under pressure to the bearings, the flow being controlled by an orifice in the supply line. Drained oil collects in the bottom of the bearing housing and is returned to the lubricating oil system through a drain pipe. When running normally, the hydrodynamic effect on the pressurised oil forms a film between the rotor journal and the bearing white metal.

i

Ii Figure 2: Bearing Lubrication System

I

Generally the recommended bearing oil is a good quality I S 0 VG32 or I S 0 VG46 turbine lubricating oil. Jacking oil is required during periods of prolonged running of the generator at low speeds (typically below 20 rpm) and maintenance operations in order to minimise generator bearing wear, and where required to reduce the shaft system breakaway torque. b 02.03.02 (A) Bearings - Fixed Profile.doc


I

BEARINGS -FIXED PROFILE -BRUSH

B E M Ltd.-


1

Issue: A

1

Date. September 2002

.. .

...

Page: 4 of 4

PRESSURE OIL SEAL I

The construction of endframe bearing machines necessitates having part of the bearing housing in the cooling air steam. To prevent the suction from the generator fans drawing oil mist from the bearings into the generator, pressurised seals are fitted at each end of the bearing. The pressurised air is derived from the downstream side of the generator fan and is taken to the seals through flexible pipes. t

JACKING OIL PANEL -BRUSH

B E M Ltd.-

Tralning Module: 02.04.03

I

Issue A

I

Date September 2002

Page 1 of 4

JACKING OIL PANEL

02.04.03 (A) Jacking Oil Panel.doc


--

--

C JACKING OIL PANEL -BRUSH

BE

M

Ltd.-

I

1 CONTENTS 1

2 3

REQUIREMENT FOR JACKING OIL ........................................................................................................3 JACKING OIL PANEL ............................................................................................................................... 3 PIPEWORK SYSTEMS ............................................................................................................................ 4

I

JACKING OIL PANEL -BRUSH

B E M Ltd.-


1I

I

Issue A

I

Date September 2002

Page 3 of 4

REQUIREMENT FOR JACKING OIL On large units, particularly those with heavy rotors, the break-away torque required to set the rotor in motion is high and excessive bearing wear would take place on starting and during low speed barring operations. A high pressure oil supply is therefore provided at the bottom of the bearing to jack up the rotor to establish an oil film before the normal hydrodynamic effect takes over.

I

I

I Figure I: Bearing Oil Supply Jacking oil is required during periods of prolonged running of the generator at low speeds (typically below 20 rpm) and maintenance operations involving low speed barring. b 2

JACKING OIL PANEL

Figure 2: Jacking Oil Panel (Typical) Oil from the main oil supply pipework system is fed through the Jacking Oil Panel, which comprise: pump(s), valves and pipework, into the generator bearings at volumes sufficient to lift the generato shaft. It is important to ensure that the main oil supply system is running correctly, and the oil inlet isolatior valve on the Jacking Oil Panel is in the open position before starting the jacking pumps. it will be note( that the jacking pump output pressure switches need to be operative to allow jacking oil to be fed to thc generator. 02.04.03 (A)Jacking O il Panel.doc


- --- - - -- --

JACKING OIL PANEL --

Before running the generator, output from the jacking oil pump should be checked to verify that the minimum specified rotor lift is being achieved (0.025mm minimum), and the system should be checked for leaks.

I

PIPEWORK SYSTEMS To prevent leaks, it is important to check the tightness of connections in pipework systems particularly following installation, maintenance and overhaul operations. Care should be taken to follow manufacturers' instructions when assemblinglre-assembling pipework compression fittings. b

02.04.03 (A) Jacking Oil Panel.doc


I

-

GENERATORENCLOSUREICANOPY -BRUSH B E M Ltd.--

raining Module: 02.05.01

I

issue: A

I

Date September 2002

Page 1 of 4

GENERATOR ENCLOSUREICANOPY

12.05.01 (A) Enclosure.doc

&,Brush Electrical Machines Ltd. 2M)

GENERATOR ENCLOSUREICANOPY -BRUSH

B E M Ltd.-


I

Issue: A

I


Page: 2 of 4

CONTENTS I ENCLOSURES ................................................................................................................................

3

1-1

-BRUSH

B E M Ltd.-

1


GENERATOR ENCLOSUREICANOPY

i

Issue: A

1

lb-f l


., .

...

Page: 3 of 4

ENCLOSURES

Figure 1: Free Standing Enclosure To allow the generator to be integrated into a packaged assembly andlor to provide acoustic attenuation, various types of generator enclosure or canopy can be provided. Enclosures can be either indoor or outdoor weatherproof types, with or without noise attenuation characteristics. Free standing enclosures complete with roof and outward opening, lockable personnel access doors in the enclosure wall can be provided for most machine types. Depending on the application, free standing canopies can be a close fit to the sides of the generator stator or can be of a 'walk through' type. Close fitting canopies have removable panels to facilitate access to the generator foundation bolts and auxiliary connections. Walk through type allows access to at least on side of the generator frame from inside the canopy. Bedpiate mounted machines can be provided with an integral enclosure built on a structural steel framework mounted on the bedplate. b

02.05.01 (A) Enclosure.doc


1-1

-BRUSH

8 E M Ltd.-

1

GENERATOR LINE & NEUTRAL CUBICLES


I

Issue: A

I

I

C


Page: 1 of 4


--

02 06 01 (A) Lane 8 Neutral Cublcles doc

--

-

.-Q Brush Electrical Machlnes Ltd 2W2

1-

-BRUSH

B E M Ltd.-

I



I

Issue: A

I

1

C


Page: 2 of 4

CONTENTS 1 LINE CUBICLES ........................................................................................................................................ 3 2 NEUTRAL CUBICLES 4 3 COMBINED LINE AND NEUTRAL CUBICLE...........................................................................................4

...............................................................................................................................

7 I

GENERATOR LINE 8 NEUTRAL CUBICLES

1

I

1

ff

I

'rn

I

LINE CUBICLES

Figure 1: Generator Line Cubicle The line connections from the generator are brought out by way of epoxy resin bushings to a line side cubicle, usually mounted on the side of the stator frame or enclosure. The line cubicle can accommodate some or all of the following: D Current transformers for protection and metering. D Voltage transformers for protection and metering. D Fused tee-off for auxiliary power supply. b Surge arresters. b Surge capacitors. t

-BRUSH

1

B E M Ltd.-

1



I

Issue: A

I

1

#


Page: 4 of 4

I

NEUTRAL CUBICLES

Figure 2: Generator Neutral Cubicle The neutral star point is usually made in the neutral cubicle, which usually accommodates current transformers for metering and protection, a high impedance neutral earthing (grounding) transformer and a secondary earthing resistor. The neutral cubicle can be free standing or mounted on the side of the stator frame or enclosure. F

3

COMBINED LINE AND NEUTRAL CUBICLE Most applications require separate line and neutral cubicles. There are however two possible applications where it is possible to house the line and neutral equipment in a combined cubicle for: 9 Steam turbine sets mounted on a mezzanine floor, where it is oflen convenient to locate the line and neutral equipment beneath the generator in a free standing combined cubicle. 9 Combined line and neutral cubicle mounted inside the a gas turbine packaged, in order to save on shipping and installation costs. F

~ doc -02 06 01 (A) Lane 8 Nebtral C L cles

GIB ~ s Electrical h Mach nes Lld 2002

GENERATOR CLEANING -BRUSH

B E M Ltd.-


I

Issue: A

I


Page: 1 of 4

GENERATOR CLEANING

02.07.01 (A)Cleaning.doc

GI Brush Electrical Machines Ltd. 2002

GENERATOR CLEANING -BRUSH B E M Ltd.Training Module: 02.07.01

I

Issue: A

1

ff


Page: 2 of 4

CONTENTS 1 CLEANING A SERIOUSLY CONTAMINATED MACHINE .......................................................................3 2 CLEANING BY HAND (PREFERRED METHOD) .....................................................................................3 3 CO, (DRY ICE) SHOT BLASTING ............................................................................................................ 3 4 JET WATER-WASH ................................................................................................................................... 4 5 POST INSULATORS AND SIMILAR SURFACES ....................................................................................4

02.07.01 (A)Cleaning.doc

@ B ~ s Electrical h Machines Ltd. 2 W 2

j-iamEm-11 -BRUSH

B E M Lid.-


rC Ji..

GENERATOR CLEANING

I

Issue: A

I


.

...

Page: 3 of 4

CLEANING A SERIOUSLY CONTAMINATED MACHINE The windings of all electrical machines will suffer from very rapid deterioration if energised in the presence of conductive contamination e.g. salt water, carbon dust etc. Consideration should be given to the removal of a seriously contaminated machine from service in order to clean the windings and core. The machine and its enclosure are designed to minimise the possibility of the cooling ducts and passages becoming blocked with dirt. However, if the cooling performance has been seriously affected by the accumulation of dirt, then the machine should be cleaned (another option is to consider completely rewinding the machine). Before cleaning a seriously contaminated machine it is usually necessary to remove the rotor. During the cleaning operation it is essential that: 9 All components are protected from the damaging effects of the weather, eg. dust, rain, moisture etc. 9 Care is always taken to ensure that contaminants are not moved into more inaccessible areas. 9 If solvents are used then the area concerned must always be well ventilated. The choice of cleaning method will depend upon the level of contamination, accessibility and availability of cleaning equipment.

A 2

Note: During the cleaning operation it is important that a safe working environment is achieved, eg. isolate electrical supplies including heaters, provide adequate ventilation, wear suitable protective clothing, use proper support for heavy items etc. b

CLEANING BY HAND (PREFERRED METHOD) Clean readily accessible surfaces by hand using an industrial vacuum cleaner, lint free cloth, brushes and, if necessary, aided by the sparing use of a solvent (e.g. Pronatur (Orange Oil) or equivalent). Any solvent used must be proven non-damaging by conducting a small trial on an easily repaired section of the winding. The winding materials must not soften or be affected in any way. Loosen accumulated dirt by using rags, brushes, blunt hooks, scrapers, strips of insulation material, wood, and probes etc. The probes are best manufactured locally from pieces of wire of between 0.7mm and 4mm diameter (carefully radius the cut ends). Pull-throughs are sometimes found useful for use on long ducts, as are bottle brushes. Take care not to damage the machine surface below the dirt layer. If a suitable working area and protective clothing, masks, goggles etc. are available, then dust and dirt may be removed using clean, dry, low pressure compressed air (1.5 - 2 Bar g). When considering the use of compressed air, please remember that many contaminants form dangerous, even toxic, airborne particles. Always scrape the dirt towards an easily accessible area for removal, never poke it deeper into the machine or allow it to fall into an inaccessible area. Suck the loosened dirt away using a high powered industrial vacuum cleaner. Account for all scrapers etc. before re-assembling the machine. Note: When cleaning the rotor it is important that the same final condition is achieved on either side of a diameter so as to preserve the balance. b

3

COJDRY ICE) SHOT BLASTING .

-

The sparing use of specialist C02 (dry ice) shot blast equipment using C02 shot blast pellets can be used where contaminants are stubborn and difficult to remove. Dry ice cleaning should be performed in conjunction with hand cleaning and should only used when dry hand cleaning becomes difficult.

02.07.01 (A) Cleaning.doc

@I Brush Electrical Machines Ltd. 2M)2

11 4

GENERATOR CLEANING

II

JET WATER-WASH If oven drying facilities are available then water-wash cleaning can be used, particularly when the machine is contaminated by materials that will dissolve in water, or water and a mild soap soiution. Keep the water pressure sufficiently low so as not to damage the machine below the dirt layer. If using a soap soiution, wash the soap away with a final rinse cycle. Clean fresh water must be used (preferably de-ionised). After washing, the machine should be dried in an oven. Set the thermostat to a maximum oven air temperature of between 125°C and 140°C. Taking readings from the embedded winding RTD's, the machine temperature must be raised to between 110°C and 120°C for 18 to 24 hours. Drying should take place as soon as possible afler washing to limit the amount of corrosion damage

5

POST INSULATORS AND SIMILAR SURFACES Wiping with cloths moistened with mild soapy water should clean these. When clean, wipe the soapy water away with a cloth moistened with clean fresh water preferably deionised. b

GENERATOR ROTOR REMOVAL -BRUSH

B E M Ltd.-


I

Issue A

I

Date September 2002

Page 1 of 10

GENERATOR ROTOR REMOVAL

02 08 01 (A) Rotor Removal doc

0 Bwsh Electrical Machlnes Ltd 2W2


B E M Ltd.-


I

Issue A

1

Date September 2002

Page 2 of 10

CONTENTS 1 INTRODUCTION........................................................................................................................................3 2 PRECAUTIONS ......................................................................................................................................... 3 3 SITE REQUIREMENTS .............................................................................................................................3 4 ROTOR REMOVAL KIT COMPONENTS..................................................................................................3 5 ROTOR REMOVAL PROCEDURE ...........................................................................................................5 6 ROTOR REMOVAL ILLUSTRATIONS...................................................................................................... 5 7 ROTOR THREADING PROCEDURE........................................................................................................ 8 9 8 ROTOR TRANSPORTATION 9 ROTOR BALANCING 10

.................................................................................................................... ..............................................................................................................................

r6RLbS~l -BRUSH


B E M Ltd.-

I


Issue. A

Figure 2: Skid Carriage

I

I

Figure 4: Support Blocks

1

1i

e


-. .

..a

Page 4 of 10

Figure 3: Skid Block b

Figure 5: Skid Carriage On Skid Plate b

Figure 6: Skid Carriage 8 Coupling Plates b


B E M Ltd.-


I5

I

I

Issue. A


I

Page: 5 of 10

I

ROTOR REMOVAL PROCEDURE Where supplied, project specific rotor removal drawings should be used. Where no project specific information is provided we recommend that our Service Department be contacted for advice. There are three basic methods of removing the rotor from the stator. P With the aid of a crane. 9 With the aid of rail tracks and trolleys. P With support blocks and rollers. b 1) Ensure that the pole faces are in the vertical plane before commencing this procedure. 2) Uncouple the generator shafl from the drive. For double end drive machines, uncouple the generator shafl from both drive ends, and it will be necessary to manoeuvre the generator into a position which will allow the rotor to be removed. This will entail one or combinations of the following: a) Sliding the generator sideways between the drive units. b) Removing the driver or gearbox at one end. c) Skewing the generator. 3) Remove the following items where applicable; wiring and conduit, exciter and air ducts, generator end covers, exciter endwvers, rotating rectifier assembly, exciter frame, oil pipes to bearings. generator bearing seals and units coupled to shafl ends. 4) Fit protection over the vibration probe 'de-glitched' track on the rotor shafl. 5) Set up lifling bracket both ends. 6) Support rotor on lifling brackets. 7) Remove bottom half bearing bushes. 8) Remove bearing endframe housings as required. 9) Insert skid plate and skid block. 10) Fit skid carriage when possible. b ROTOR REMOVAL ILLUSTRATIONS

Figure 7: IRotor Supported On Lifting Brackets

02.08.01 (A) Rotor Rernoval.doc

Figure 8: Support Platform In Place b


1-1

-BRUSH

B E M Lid.-

1


I


issue: A

-

Figure 9: Rotor Supported Endframe Lowered

I

li-e


..

.

...

Page: 6 of 10

Flgure 10: Rotor Supported At Drive End b

Figure 11: Rotor Protection Collar 8 Skid Carriage In Position (Drive End) b

Figure 12: Rotor Passing Through Stator

02.08.01 (A) Rotor R e r n 0 v a l . d ~ ~

.

-Figure 13: Brake Applied To Rotor F

O Bwsh Electrical Machines Ltd. 2M)2


6 E M Ltd.-


I

Issue A

Figure 14: Rotor Set Down On Journal

I

Date September 2002

Page 7 o f 10

Figure 15: Rotor Slung Around Body Centre b

Figure 16: Rotor Removed b

12.08.01 (A) Rotor Removal.doc

-


C

GENERATORROTORREMOVAL B E M Ltd.Training Module: 02.08.01 -BRUSH

7

I

Issue: A

I


Page: 8 of 10

ROTOR THREADING PROCEDURE Rotor threading is the reverse of rotor removal procedure.

Figure 17: Rotor Threading The rotor is threaded into the stator as far as the slings allow. b

1

I

I

Figure 18: Pulling Plate 8 Skid Carriage The pulling plate and shackles are fitted to the rotor coupling. The skid carriage, which is sitting on the skid plate, is fitted to the shaft. b

Figure 19: Rotor Pulling Using Overhead Crane In this illustration, the rotor is pulled into the stator using an overhead crane. Wire rope passes through the wheel assembly, which is anchored to the floor. b

02.08.01(A)Rotor Removal.doc

O Brush Electrical Machines Ltd. 2 W 2

I

I

. -BRUSH

B E M Ltd.-


I

Issue: A

I

@

i Date: September 2002


* .

I

...

Page: 9 of 10

The following should be checked (Refer to Operating 8 Maintenance Manual): 1) Bearing insulation. 2) Coupling alignment 3) Alignment of bottom half bearing bushes, using of feeler gauges inserted between the bearing and shaft (both sides at each end) - before fitting the top half of the bearings. 4) Generator and exciter fan clearances. 5) Bearing seal settings. b 8

ROTOR TRANSPORTATION If the removed rotor is required to be transported, it is necessary to ensure that the rotor is supported in the best possible position to avoid damage due to axial or lateral movement. In addition, the rotor must be fully protected against damage caused by both exposure to adverse climatic conditions and the abrasive effect of wire ropes or slings. In general, a wooden packing case will be required for long duration journeys. For short journeys a tarpaulin can be used as a covering after the rotor has been protected as detailed hereafler. All exposed bare metal sections of the rotor shafl ends, such as bearing journals, thrust collars, proximity probe tracks and couplings, are to be given a protective coating of She1 'Ensis K' fluid or a suitable grade of heavy grease. In addition, the bearing journals and proximity probe tracks are to be wrapped with polyester film, which should be taped in position. Preferably, the rotor should then be sealed in a seet bag (a heavy duty plastic bag with a metal foil barrier) or similar enclosure. For transportation by sea, this type of packing should always be used. For long term storage the seet bag should contain silica gel desiccant and a visible litmus humidity indicator, or similar. If a seet bag or similar enclosure is not available, both ends of the shafl, including, when applicable, the main exciter armature and the pilot exciter magnet, should be completely wrapped with heavy gauge polythene sheet, taped as necessary to seal against the ingress of moisture and other contaminants, and silica gel bags should be included inside the wrapping, with openings in the rotor body taped over with brightly coloured adhesive tape. Two suitably constructed wooden cradle blocks are needed to securely support the ro!or within the box or on the vehicle platform or trailer. These should be profiled to suit the outside diameter of the centre body section of the rotor. The blocks must be positioned approximately 100mm 150mm from each rotor endcap (See diagram) and the rotor arranged with the poles in the top and bottom positions such that the weight is taken on the solid steel pole section and not on the winding slot area.

-

Rotor Transportation Supports To prevent any possible axial movement of the rotor, a suitably Const~Ctedaxial restraint device is needed. This device must be integral with the transportation box and sufficiently robust to prevent distortion under the shock conditions associated with rapiddeceleration. The rotor should be attached to the restraint structure by bolts passing through the holes in the rotor coupling flange. These bolts must be protected with sofl steel washers to prevent damage to the coupling face.

02.08.01 (A)Rotor Removal.doc

D Brush Electrical Machines Ltd. 2 W 2

I


B E M Ltd.-


I

Issue. A

I

I

I


1

Page:lOofIO

The rotor must be firmly lashed down inside the box and to the vehicle to prevent any possible movement in transit. This should be achieved using wire ropes or webbing straps with suitable tensioning devices. Chains should not be employed as these are difficult to tension correctly. The lashing should only be applied over the centre body section of the rotor; on no account must the ropes bear on the shaft ends or the rotor endcaps. Damage to the rotor body surface can be avoided by the use of hard protective sheet material under the wire ropes. When the transport contractor is completely satisfied that the rotor is secure (in the case of a boxed rotor, it must be ensured that the rotor is secure in its box and that the box is secure), it should be completely sheeted over with a waterproof tarpaulin or plastic sheeting. The sheeting must be firmly tied down all round to prevent contamination of the rotor from adverse climatic conditions. Note: For road and sea transport, in addition to the normal force of gravity, 'g' forces of up to l g in any direction can be expected. For rail transport, very much higher forces can be experienced and the advice of the Railway Company should always be sought. b 9

ROTOR BALANCING The field balancing of generator rotors is a specialist subject and should not be attempted unless the specialist knowledge of Modal Balancing techniques is available. Brush Electrical Machines Ltd. have specialist engineers available should there be a need to re-balance the rotor. Before attempting to adjust the balance weights, a careful record should be made of the balance weights and their axial and angular positions so that the original balance conditions can be restored. This record should be made for each balance plane that it is proposed to disturb.

/

I

Note: Record the original condition of the balance weight BEFORE adjustment.

-

Balance weight planes exist on the rectifier fan of brushless machines or on the sliprings of slipring machines, on each fan, on the outboard end of each end cap, and on the rotor body.

I

Screwed-plug type balance weights should be screwed flush with the rotor surface and locked by peening into the screwdriver slot or small, semi-circular grooves (the slot or grooves being at approximately 45" to any major axis). Dovetail type balance weights should have the grub screw tightened with a hexagonal wrench and then be secured by peening, to lock both the grub screw and the edges of the dovetail groove, to prevent circumferential slippage.

I

I

Report any weight changes made to Brush Electrical Machines Ltd.. Service Department. Note: Additional balance weight planes can be made available by the judicious adjustment of the coupling bolt weights if required. Note: All dovetail balance weight grooves have limits to the quantity of weights that should be fitted for continued component stability. As a general rule, no more than 3 additional weights should be fitted in the end caps, and 5 in other balance planes without first getting the approval of the Brush Electrical Machines Ltd. b

I

1-

-BRUSH

B E M Ltd.-

RESISTANCE TEMPERATURE DETECTORS 8 THERMOCOUPLES

'raining Module: 03.01.01

I

Issue: A

I


Page: 1 of 4

RESISTANCE TEMPERATURE DETECTORS & THERMOCOUPLES

3.01.01 (A) RTDs 8 ThermocouPles.doc

O Brush Electrical Machines Ltd. 2002-

CONTENTS . .

I 2 3

4 5

GENERAL .......................................................................................................................................3 RECOMMENDED ALARM (L TRIP SETTINGS ................................................................................. 3 RESISTANCE TEMPERATURE DETECTORS ........................................................................... 4 OVERVOLTAGE PROTECTION 4 RTD CALIBRATION ............................................................................................................................. 4 .

....................................................................................................... ~~~~~

~

~

1-

-BRUSH

B E M Ltd.-

RESISTANCE TEMPERATURE DETECTORS 8 THERMOCOUPLES Page: 3 of 4

11

GENERAL

Resistance Temperature Detectors And Thermocouples Figure I: The resistance temperature detector (RTD) or resistance thermometer uses the fact that the resistance of metals increases with temperature. Generally, the higher the resistance, the less affected the RTC will be due to small resistance/voltage fluctuations in the lead wires etc. The Thermocouple is a thermoelectric temperature sensor which consists of two dissimilar metallic wires. These two wires are connected at two different junctions, one for temperature measurement and the other for reference. The temperature difference between the two junctions is detected by measurin~ the change in voltage (electmmotive force, EMF) across the dissimilar metals at the temperature measurement junction. RTD's or thermocouples are fitted to the generator to monitor temperatures in the various parts of the machine. These detectors, or if specified separate temperature switches (thermostats), are commonly used to initiate trip and alarm functions. The location of these devices are illustrated on the drawings.

Unless stated otherwise in the Operating & Maintenance Manual, recommended alarm and trip settings are as follows:

I Parameter Stator Winding Temperature (OC) Bearina Oil Outlet Temoerature l°Cl Bearing Metal Temperature ('C) Thrust Bearing Metal Temperature ("C) Exciter Air Outlet Temperature ('C) Generator Air Outlet Temoerature f°Cl

03.01.01 (A) RTDs 8 Thennocouplesdoc

I

Alarm

150 87 92 105 105 105

I

Trip

I

160 90 95 110

0 Bmsh Electrical Machines Ltd. 2002

1-

-BRUSH

RESISTANCE TEMPERATURE DETECTORS 8 THERMOCOUPLES

B E M Ltd.-

I


Issue: A

I

I'rf fGl#fmmm -, . ..


Page: 4 of 4

RESISTANCE TEMPERATURE DETECTORS Unless stated otherwise in the Operating 8 Maintenance Manual temperature detectors of the resistance type comprise an element with a non-inductively wound platinum coil having a value of IOOQ at O°C. Operation of the detector is based on the principle that the resistance of a metallic conductor varies linearly with temperature. Three leads are brought out of the machine from each detector, two from one end and one from the other. In this way the detector can be connected to a Wheatstone Bridge resistance measuring circuit. so that variations in lead resistance do not affect the bridge reading of detector resistance. Ovewdtage Prdedion Device

m /

Resistor

Resistor

0 h

-

Three Wire RTD Measuring Instrument Circuit Diagram b OVERVOLTAGE PROTECTION The RTD's embedded in the stator winding are protected against potentially lethal voltage build-up using ove~oltageprotection devices built into the Klippon terminals. To operate successfully, one side of the protection device must be connected to earth and the other connected to the RTD lead (achieved as it passes through the terminal block). RTD's located in other parts of the machine do not have overvoltage protection devices fitted.

5

RTD CALIBRATION Tables of RTD calibration data (resistance versus temperature) can be found in Suppliers Data file:

ALSO002

Platinum Resistance Temperature Detectors,

03.01.01 (A) RTDs 8 Thenocouples.doc


LiusH1

1-1

-. ="ing .

B E M Ltd.-

_

--

-

BENTLY NEVADA VIBRATION MONITORING

-

Module: 03.02.01

.-

~s sb e : A [Date: Septembe3gZ

CONTENTS 1 VIBRATION MONITORING ....................................................................................................................... 3 1.1 Proximity Probe System ...................................................................................................................... 3 1.2 PROXPAC@ 1.3 Settings ...... 2 VELOCITY & ACCELERATION TRANSDUCERS ................................................................................... 5 3 MEASUREMENTS ON ROTATING MACHINERY ....................................................................................5 ................................................................. 5 3.1 Non-Contacting Relative Displacement .................... . . . 3.2 lnerlially Referenced Displacement, Velocity and Acceleration 6

1-1

-BRUSH

B E M Ltd.-

I

BENTLI NEVADA VIBRATION MONITORING

I


Issue: A

1

1

#


Page: 3 of 6

I

VIBRATION MONITORING Proximitv Probe Svstem

I

I

Figure I: Vibration Monitoring The proximity probe system can provide monitoring for radial vibration, axial (thrust) position, speed, and phase (Keyphaso63) measurements. b

Figure 2: Bently Nevada Proximity Probe System The proximity probe system consists of: 9 Probe 9 Extension cable F Proximito63 Sensor Bently Nevada eddy current proximity probes, or transducers allow direct obselvation of shaft displacement for a variety of vibration, position, speed, and timing (i.e. phase) measurements, and measure actual shaft motion. The system provides an output voltage directly proportional to the distance between the probe tip and the observed surface. It is capable of both static (position) and dynamic (vibration) measurements, and is primarily used for vibration and position measurement applications on fluid-film bearing machines.

---

-

03 02 01 (A) V braloon Monllonng BN Ooc

--

.0 Brush Electrical Machmes Ltd 2002

1

BENTLY NEVADA VIBRATION MONITORING Issue: A

I

Date:

The system allows interchangeability of probe, extension cable, and Proximito@ Sensoi without the need for individual component matching or bench calibration. The ProximitonB Sensor can be mounted on a DIN-rail or in a traditional panel. b 1.2

PROXPAC@

Figure 3: Bently Nevada PROXPAC@ PROXPAC@is a single package comprising the proximity transducer, housing and extension cables. Field wiring to the monitor system can then be run directly to the housing assembly. The PROXPAC@ proximity transducer assembly contains its own Proximitot@ Sensor inside the housing's cover. This design makes the PROXPAC@ assembly a completely selfcontained proximity probe system, and eliminates the need for an extension cable between the probe and its associated Proximito& Sensor and housing. V

Unless stated otherwise in the Operating & Maintenance Manual, the usually recommended settings are as follows: Parameter Shaft Relative Vibration", Peak To Peak (wm [inches])

I

I

Alarm 100 [0.004]

Trlp 150 [0.006]

If vibration is measured in terms of ampllude: Zero To Peak Amplitude (pm) = (Peak Velocity (mmls) x 9550Yrpm

b

-

1.02.01 (A) Vibration Monitoring BN.doc


1

1-1

-BRUSH B E M Ltd.Training Module: 03.02.01 2

I i-

P

BENTLY NEVADA VIBRATION MONITORING

I

I

Issue: A

..


...

Page: 5 of 6

VELOClTY8ACCELERATlONTRANSDUCERS

Unlike proximity probes which observe the machine's shaft directly, casing vibration transducers measure the vibration of the surface to which they are attached - usually a bearing housing. Devices in this category include both accelerometers and velocity transducers. Unless stated otherwise in the Operating & Maintenance Manual, the usually recommended settings are as follows: Parameter Bearing Housing. Vibration Peak Velocity (mmls [inchesls])

"

I

I

Alarm 9 10.351

Trip 19 [0.75]

" If vibration is measured in terms of amplitude:

Zero To Peak Amplitude (pm) = (Peak Velocity (mmls) x 9550)11pm

t 3

MEASUREMENTS ON ROTATING MACHINERY The following conventions have been generally adopted for polarity and phase referencing of transducers, data storage and data presentation. They are fully independent of the direction of rotation. dynamic impedance and dynamic action of the machine, and have been developed so as to remove possible ambiguity. 3.1

Non-Contacting Relative DiS~lacement

-von Vonage Toward Positwe (+)

0

0 von*

Motion Toward Probe

8

,-Gap

+ VOltS

Gap in mils or micrometres Decrease Gap increase-

0

(for reference only)

Figure 4: Non-Contacting Relative Displacement Measurement Motion toward the transducer along its sensitive axis shall produce a positive (+) magnitude of voltage or current. The polarity of a relative displacement transducer such as the Bently Nevada proximity probe is easily tested by decreasing gap as shown in Figure 4. The gap can be decreased by either moving the probe towards the observed material, or by moving the observed material towards the probe. b

-

03.02.01 (A)Vibration Monitoring BN.doc


(

B E N T L I NEVADA VIBRATION MONITORING

-BRUSH B E M L1d.Training Module: 03.02.01

I

Issue: A

I

I*


Page: 6 of 6

lnertiallv Referenced Displacement, Velocity and Acceleration

rF(

Transducer

+/

Time (+)

-

Sensitive Axis Displacement. Velociru, or Acceleration

fv U

Tap Lightly

(-)

Time Base presentation

Figure 5: lnertially Referenced Displacement Measurement The polarity of lnertially referenced displacement, velocity or accelerometer transducers is easily tested by means of a tap test. The tap test consists of lightly tapping the transducer in its sensitive axis. The resulting time based waveform, as shown in Figure 5, is an initially positive (+) going output signal when tapped toward the sensitive axis. b

-

03.02.01 (A) Vibration Monitoring BN.doc


i

POWER GENERATION SYSTEMS -BRUSH

B E M Ltd.-

I


issue B

I

a

Date Apr112003

*

..

Page 1 of 14

POWER GENERATION SYSTEMS -

PMG EXCITER

O PRIME MOVER

r ROTOR

? ROTATING RECTIFIER

STATOR

-

19

SENSING

VT CT

n'n'n' LOAD

04.01.01 ( 6 )Power Generation Systerns.doc


CONTENTS I PRIME MOVERIGENERATOR ................................................................................................................3 1.1 Arrangement 3 1.2 Prime Mover ................. a 1.3 Generator & 4 2 GENERATOR OPERATION ..................... ............................... 5 2.1 General................................................................................................................................................ F 2.2 Island Operatio 5 2.3 Parallel Operation................................................................................................................................6 3 AUTOMATIC VOLTAGE CONTROL......................................................................................................... 7 4 PARALLEL OPERATION 8 Quadrature Current Compensation .......................... . . . .......................................................... 8 4.1 10 Machines In Parallel.......................................................................................................................... 4.2 5 GOVERNOR DROOP I1 . . ........................................................................................................................11 Introduction.......... 5.1 . ........................................................................ 12 Case 1 Zero Droop (Isochronous) .................... 5.2 Case 2 -With Droop ..........................................................................................................................12 5.3 6 GENERATOR OUTPUT .......................................................................................................................... 13

............

-

..........................................................................................................................

..............................................................................................................................

-

4.01.01 (8) Power Generation Systems.doc


I

~04.01.01

I

Issue: B

Date: April 2003

1

Page: 3 of 14

I

PRIME MOVERIGENERATOR 1.1

Arranqement

PRIME MOVER

r

t ,

Governor

Raise Lower

GENERATOR

I

t

,

H

Raise Lower

Figure 1: Main Components Of A Generating Package 1.2

Prime Mover & Governor The prime mover is mechanically linked, or coupled, to the generator either directly or by a gearbox. It would typically be a turbine (gas, steam, water or wind) or a diesel engine. Its function is to rotate the generator. As the generator is usually a synchronous machine, the rotational speed is required to be kept fairly constant and this is the function of the governor. Modern governors are normally electronic, providing a fast, closed loop control but the output may take many forms to suit the prime mover being controlled. The governor output can be a fuel, water or gas valve; being opened to increase speed or closed to reduce it. Some form of speed signal is fed to the governor and compared with an adjustable reference. The difference, the error, is used to control the output. The speed to which the governor controls, the speed datum, is adjustable over a small range; the adjustment usually being made by means of a 'speeder motor' in the case of mechanical governors or by an upldown counter in electronic units. The raisellower signals might come from a control switch, an automatic synchroniser or an automatic control system. b

b 0 1

--

01 (6)Power Generallon Systems doc

-.

---

O Bnsh Eleclncal Machines Lld 2003

POWER GENERATION SYSTEMS

1.3

I 'r , C

Generator 8 AVR The Generator converts rotational mechanical energy produced by the prime mover int electrical energy. Figure 2 illustrates how the various elements are connected to a brushless generator AVI system.

-

PMG EXCITER

I

U

PRIME MOVER

D ROTATiNG RECTIFIER

ROTOR STATOR

-

TG?q

SENSING VT CT

it!' LOAD

Figure 2: GeneratorlAVR Block Diagram The purpose of the pilot exciter is to provide a source of excitation power whenever the machine is running. The pilot exciter is a single phase permanent magnet generator (PMG), with the magnets mounted on the shaft, and the AC output being generated in the stator. The main exciter is of the brushless type and comprises a fixed part called the main exciter stator, and a rotating part called the main exciter armature. The main.exciter stator is comprises laminated steel field poles around which are the field coils. t The three phase AC output from the main exciter armature is connected to the rotating rectifier assembly, which converts the AC output to the DC input required in the generator rotor winding (See Figure 3) . The rotating rectifier assembly is a three phase full wave bridge configuration, with fuses in series with each rectifier diode. On larger machines more than one fuselrectifier diode may be fitted to each arm of the bridge. Electrical connections between the rectified output and the generator rotor winding are carried in the central bore through the machine shaft.

04.01.01 ( 0 )Paver Generalion Sys1ems.doc

0 Brush Electrical Machines Lld. 2003


B E M Ltd.-


I

Issue B

I

Date Apr112003

Page 5 of 14

1

......................

I

Pasitwe Heat Sink

: I

NegativeH& Sink

:

........................

?__-.-.-.-.-.-.-.-.-.-.-.---.-.--

I I

Figure 3: Brushless Generator Schematic The voltage regulator allows the Operator to control the generator's voltage by variation o excitation. This is called 'excitation control'. To make the process automatic, an electronic device called an Automatic Voltage Regulator (AVR) or Excitation Controller is used tc sense the output voltage and compare it with a preset datum. The AVR decides whether tht output voltage is correct, too high or too low. The power output of the machine is produced in the generator stator windings. b !

GENERATOR OPERATION 2.1

General The power (MW, kW, W or Watts) supplied at the generator terminals is provided by the fue supplied to the prime mover (turbine or engine), which is determined by the prime move governor. When a generator is used to supply power, it can be operated isolated, sometimes referred ct as island mode, or in parallel with a system or other machines.

2.2

Island Operation In island operation, the machine speed is determined by the load and fuel supply, and the generator voltage is determined by the excitation. Because the unit operates in isolation, the generator power factor is equal to the load power factor.

4.01.01 (8) Power Generation Systems.doc

Q Brush Electrical Machines Ltd. 200:

C POWER GENERATION SYSTEMS -BRUSH

B E M Ltd.-

I


Issue: B

I

Date: April 2003

Page: 6 of 14

-

FUEL

FUEL REWLATOR

-

MECHANICAL FoVER

\

PMME MOMR

2

ELECTRICAL r n R

LOAD

GENERATOR

A FIELD

GOMRNOR

+

C

SEED SIGNAL

VOLTAGE RE-m

VmTffiE SlGNAL

Figure 4: Island Mode Operation When operating in isolation, an increase in load will have two effects:

1) Speed will initially fall because the energy being supplied by the fuel is less than that required by the load. The speed reduction is detected by the governor, which opens the prime mover fuel valve by the required amount to maintain the required speed. 2) Voltage will initially fall because the generator excitation is too low to maintain nominal voltage at the increased load. The voltage reduction is detected by the automatic voltage regulator (AVR) which increases the excitation by an amount required to maintain output voltage. b Parallel Oueration

2.3

- -

ElEmCAL POIlKR

MEWICAL POWER

'

-

FUEL

FUEL

REOVLAlW.

PWM

V

GENEFATOR

LARGE POWER SYSTEM

A FlEm

v +

V a T E REGULATOR

I

SENSlw SIGNALS

Figure 5: Parallel Operation When a machine operates in parallel with a power system, the voltage and frequency will be fixed mainly by the system. The fuel supply to the prime mover determines the power which is supplied by the generator and this is controlled by the governor.

I

The generator excitation determines the internal emf of the machine and therefore affects the power factor when the terminal voltage is fixed by the power system. The governor and AVR are arranged to have characteristics which allow them to be stable when the generator is operating in parallel with a power system. (See Section 4 - Parallel Operation).

04.01.01 (B) Power Generation Systemsdoc


-

-BRUSH 8 E M Ltd. Training Module: 04.01.01

li-e


I

Issue. B

I

Date: April 2003

-. ... Page: 7 of 14

In single and parallel operation it is important to realise that power is determined by the fuel supply to the prime mover, and that excitation determines voltage when single running, and power factor when parallel running. b 3

AUTOMATIC VOLTAGE CONTROL BRUSHLESS GENEPATOR

PILOT EXCITER

VOLTffiE B CURREM SENSING TRANSK)RMERS

--

,T ,

/

CM.mMUE0 RECnFlER

SIw.u\L

PDJUSTPBLE REFERENCE VOCTffiE

PMRlFlER

STPBILISIW N m

Figure 6: Principal Components Of A Generator And AVR The above diagram shows the principal components of the generator and its AVR. The voltage transformer (VT) provides a signal proportional to line voltage to the AVR where it is compared to a stable reference voltage. The difference (error) signal is amplified and then used to control the output of a thyristor rectifier which supplies a portion of the PMG output to the exciter field. If the load on the generator suddenly increases the reduction in output voltage produces an error signal which, when amplified, causes an increase in exciter field current resulting in a corresponding increase in rotor current and generator output voltage. Conversely, load reduction will cause the generator voltage to suddenly increase, and in this case the amplified error signal will cause a reduction in exciter field current resulting in a corresponding reduction in rotor current and generator output voltage. Because of the high inductance of the generator field windings, it is difficult to make rapid changes in field current. This introduces a considerable 'lag' in the coritrol system which makes it necessary to include a stabilising circuit in the AVR to prevent instability and optimise the generator voltage response to load changes. Without a stabilising circuit, the regulator would keep increasing and reducing excitation and the line voltage would continuously fluctuate above and below the required value. Modern voltage regulators are designed to maintain the generator line voltage within better than *I% of nominal for wide variations of machine load. b

14.01.01 ( 8 ) Power Generation Systems.doc



I

PARALLEL OPERATION 4.1

Quadrature Current Comuensation As mentioned earlier when a generator is connected in parallel with another power system i may be incapable of significantly influencing the system line voltage, with the level o excitation now determining the reactive power developed by the generator. If line voltage were less than that called for by the voltage regulator, it would supply maximum available excitatior in an attempt to increase line voltage and excessive lagging reactive line current would flow. Similarly, if line voltage were high, excitation would be reduced to zero in an attempt to reduce line voltage, and excessive leading line current would flow. Under such circumstances the generator could pole slip (run asynchronously) if any significant power were flowing. A standard method of overcoming the above problem is to modify the voltage control system so that as lagging reactive load on the generator increases, the line voltage that the regulato~ demands is reduced as shown in Figure 7 in which it will be seen that as the system voltage falls from level A to level 6 the lagging reactive current increases. For a fixed line voltage, generator reactive current may be varied by adjustment of the voltage setting potentiometel which adjusts the position of the AVR characteristic. GENERATOR LINE VOLTGE

A & B REPRESENT TWO SYSTEMVOLTGES

I

4 LEADING

0

w

LAGGING REACTlM CURRENT

Figure 7: Voltage Control Characteristic For Parallel Operatlon A method of achieving the above AVR characteristic is known as Quadrature Current Compensation (QCC). A voltage proportional to one line current is added to the voltage across the other two lines and the amplitude of the vector sum is regulated by the AVR as illustrated in the following diagram. b

101.01 (8) Power Generation Systems.doc



B E M Ltd.-


I

I

Issue: B

Date: April 2003

Page: 9 of 14

SCHEMATIC DIAGRAM I L

v

m n

b b b

"1

A m

VECTOR DIAGRAMS

C Figure 8: Quadrature Current Compensation It will be seen that the sensing voltage, V,, is the vector sum of line voltage and a voltagt proportional to the line current signal, Vc. If line voltage is much greater than VC, the followin! approximation way be made.

V, = VBA+ VCsin $ where C$is the phase angle Thus as lagging reactive load increases, so does the last term of the above expression whicl is proportional to reactive current, and therefore line voltage is reduced as the AVR acts tl maintain V1 constant. For leading reactive currents, line voltage is increased. The reduction il line voltage for rated current at zero power factor lagging is typically 5%. Provided line voltage does not vary, reactive current will be controlled to a level determined b the voltage setting potentiometer of the AVR. If, however, line voltage varied appreciably, a1 Operator would have to continually adjust the potentiometer to prevent excessive lagging 0 leading currents. Under such circumstances it may be desirable to use an automatic reactiv' current or power factor control system. b

04.01 0 1 (8) Power Generation Systerns.doc



B E M Ltd.-

I


1

4.2

I

Issue: B

- a

I

Date: Apr~l2003

...

Page. 10 of 14

Machines In Parallel Where a number of machines are operated in parallel, it is usual to adjust the regulators to give a similar amount of droop. This will ensure that the total VAR loading on the system remains reasonably balanced between generators. If droop settings are not equal, the machine with the least droop will tend to take more than its share of the load VARs. This means that the set with least droop will run at a lower lagging power factor than the others.

&ax3 TOTPLVPRS (SET BY LOAD)

B

A

ARBHAM E W A L DROOP

C

C HAS LESS DROOP THAN A& B

VOLTffiE

A SYSTEM VCLTPGE

ABB

LEAD

0

LAG

VPRsOn ARB

VpRs On C

VARs

In the above diagram, machines A and B have identical droop and at a particular line voltage will supply equal VARs. Machine C has less droop and will therefore supply more VARs than A or B, at the same line voltage. When a machine operates in parallel with an infinite busbar as shown in the following diagram, the busbar behaves like a machine with zero droop, therefore if the busbar voltage remains constant, the generator will produce constant VARs. b

I

il 1


INFINITE BUSBAR

7 A

GENERATOR

INCREASING AMI SET POINT

VOLTAGE

I

--->-

x \A

---__-----

SYSTEM VOLTAGE

-----__ ---___ ----___

Y

r

CHARACTERISTIC OF MACHINE A

LEAD

0

t VPRS

LAG

Figure 10: Machine In Parallel With Infinite Busbar To adjust the VARs on the machine it is necessary to raise or lower the position of line X-Y b) adjusting the AVR datum. This is the usual method of manually adjusting VARs or Powel Factor. b i

GOVERNOR DROOP 5.1

Introduction When operating in parallel the prime mover fuel control system is also changed from 2 constant frequency control system to one which can operate when the frequency i: determined by the grid system. A simple arrangement often used is known as governor d r 0 0 ~ where the governor speed datum is reduced as the load increases. SPEU)

(FREWWCY)

I ~ i f f i G-SET PolM

1 . r --

S Y r n FREWENCY

--.-__

-----------__._______ Y

lm%

0

rPOWER

Figure 11: Governor Droop Characteristic

in this simple arrangement the system frequency determines the point on the characteristic and adjustment of the governor datum will raise or lower the line Y-Y and allow the load to bt adjusted. As in generator controls, wide variations of system frequency would give rise to large powe variation and in such cases it would be normal to include an automatic load control system il the governor. b

14.01.01(El) Power Generation Systems.doc

O Brush ElectricalMachines Lld. 2W

ff


5.2

Case I-Zero Droop (Isochronous~ To explain the need for speed droop consider firstly the case of two generating packages without droop. These are required to run in parallel on an 'Island' system such as an isolatec oil rig.

-

Consider Package A, set to 50Hz, already on the bars and loaded to about half full load nc problem here. If the load should vary, the governor will adjust the fuel to bring the speed back to 50Hz. Now if Package B was needed, it would be synchronised to the bars usually by setting it a little faster, say 50.1Hz. Once the breaker is closed, the two sets are locked together and the troubles begin. The common speed of the two packages is likely to be somewhere between 50 and 50.1Hz. The governor on Package B will see this speed as too slow and increase the fuel supply. At the same time Package A's governor will see the speed as too fast and reduce fuel. Neither of these actions change the situation and the governors continue to fight, Package B will take all the available load and Package A will trip on reverse power. b

5.3

Case 2 -With D r o o ~ Now consider what happens when this is repeated but with the governor of Package B having droop. As before, Package B's governor sees the speed as too low and increases fuel and again Package A's fuel is reduced, but, as the power provided by B increases so its speed setting is reduced automatically by the droop mechanism and soon falls to 50Hz at which point both governors are happy. The governor of Package A with zero droop is said to be 'isochronous'. Figure 12 shows the characteristics of two such packages, one with droop and one isochronous. lsochmnws Droop

V)

0%

Load

I 1W%

Figure 12: lsochronouslDroop Characteristics If further sets are needed on the bars then they too must have speed droop. Just one set may be left in the isochronous mode and this set then effectively controls the frequency of the whole power system. Such an arrangement may seem ideal but, apart from the difficulty of ensuring that one, and Only one of the sets is isochronous, there is another problem: any load change is thrown solely onto the isochronous set. .It is more common to give all sets equal droop and in this way any load changes are shared equally between the running sets. The slight reduction in frequency as load is applied is a small penalty to pay for an inherently stable arrangement. In any case, a power management system such as PRlSMlC will off-set this and keep the system frequency constant in the long ten. b

04.01.O1 ( 6 )Power Generation Systems.doc


I

5

GENERATOR OUTPUT The generator is usually the only load driven by the prime mover and this produces a three phase output at a voltage to suit the distribution arrangement of the power system. Typical nominal voltages are 600V, 3300V, 6600V. 11,000V or 13,800V. The design of the generator determines the voltage it can produce, but merely spinning the machine will only generate about 5% nominal volts (produced by the residual magnetism of the rotor). To produce full voltage the generator has to be excited. In the case of a brushless generator this is done by applying a DC voltage to the exciter field. The control of the generator output voltage by this means is the job of the automatic voltage regulator (AVR). The task of any AVR is to maintain the generator voltage at a set level. A dip in voltage caused by an increased load on the machine will be compensated by increasing the voltage applied to the field. Modern AVRs employ semi-conductor devices to provide excitation and offer a fast response to maintain line voltage in the face of varying loads. Like the governor, the AVR has a droop characteristic but, in this case, it is the voltage that falls and with increasing reactive rather than real power (See Training Module 04.10.01). The voltage droop is can be set between 0 and lo%, a value of 4% being common. The droop allows the generator to share reactive power stably with other paralleled machines. The generator is selected to match the speed and power of the prime mover; the output frequency is given by the following formula:

where:

f is the generator frequency N is generator speed in revs per second p is the number of pairs of poles on the generator

Thus a four-pole generator running at 1500 rpm (25 revslsecond) will give a frequency of 50Hz. b

4.01.01 (6)Power Generation Systems.doc


[~RUSHI -BRUSH

B E M Ltd.-



I

Issue: B

I

BLANK PAGE

e I b a 1l E m i m .I. m 2003 * a

Date: April

Page:14of14

SYNCHRONISING

SYNCHRONISING

SYNCHROSCOPE

l4.02.01 (A) Synchronising.doc


pmiw -BRUSH

BEM

Training Modu

CONTENTS 1 INTRODUCTION........................................................................................................................................ : 2 DC GENERATORS .................................................................................................................................. : 3 AC GENERATORS.................................................................................................................................... 4 4 SYNCHRONISING AC GENERATORS .................................................................................................... ! 5 LAMP SYNCHRONISING .......................................................................................................................... t f 5.1 The 2-Lamp Method .......................................................................................................................... 5.2 The 3-Lamp Method ....................... .............................................................................................. : 5 SYNCHROSCOPE..................................................................................................................................... I 7 SYNCHRONISING AT THE SWITCHBOARD/CONTROL PANEL ..........................................................t < 3 AUTOMATIC SYNCHRONISING a 3 CHECK SYNCHRONISING 10 CLOSING ONTO DEAD BUSBAR I(

. . .

............................................................................................................... ........................................................................................................................ ......................................................................................................

1.02.01 (A) Synchronisingdoc

Q Brush Electrical Machines Ltd. 200:

SYNCHRONISING -BRUSH

B E M Ltd.-


/

1

1

Issue A

I

Date Apr112003

Page 3 of 10

INTRODUCTION The idea of synchronising is not new. Every time you change gear in a car you synchronise the engine to the road speed so that, when the clutch is let in, both shafts are running at the same speed and there is no jerk. Conversely, if you synchronise badly there is a jerk, stress on the engine and possibly a lot of noise.

I

In electrical engineering, synchronising is to either electrically Toin' the output of an AC generator to a live busbar, or join live bus sections together. Generator synchronising is applicable to installations that have more than one generator andlor are connected to another (external) network or grid.

/

I

When synchronising two electrical systems, the moment the circuit breaker closes the systems are mechanically locked through the busbars. Any synchronising displacement will cause the smaller of the systems to lock very quickly resulting in mechanical stresses in the both the prime mover and generator rotors and foundations. In turbines blades can be damaged. In generators windings and rotating diodes can be damaged due to the high transient currents that can occur during this 'fault' condition. b 2

DC GENERATORS The simplest case of synchronising occurs with dc generators.

Figure I:DC Generators Figure 1 represents two dc generators, both on open circuit but about to be paralleled by a switch. Each is separately excited such that machine 'A' has an open-circuit voltage VA and.machine '6' VB. Machine 'A' is assumed to be the 'running' generator, and machine '6' , is the 'incoming' generator which is to be paralleled to 'A'. Before closing the switch which puts the two generators in parallel it is necessary only to ensure that their voltages are the same -that is, that VB = VA ; then the switch may be closed, and no sudden current will flow - there will be no electrical Terks'. If the voltages were different, suppose that VA is greater than VB. On closing the switch there will be a closed loop with the emfs VA and VB opposing one another. Since VA is greater than VB there is a net clockwise emf in the loop, which will cause a clockwise current lcto flow round it (shown in red), limited only by the resistances of the two armatures. This current appears suddenly as the switch is closed, putting a sudden load onto generator 'A' so causing it to slow with a jerk, and causing generator '6'to motor, making it accelerate with a jerk. This circulating current, which occurs on closing the switchwhenever VA and Vg are not equal, is also called the 'synchronising current'. To avoid it and its consequent jerking effect on the system, the incoming machine voltage must first be matched to the voltage of the running machine - normally done by trimming the field of the incoming generator. t

I

I

I

AC GENERATORS

With ac generators the problem is more complicated. It can be seen in the dc case how a circulatin! current is caused by differing opposing voltages. In dc this is straightfornard, but in ac a voltage difference can be caused either by differing voltage amplitudes or, for the same voltage amplitudes, b~ differing phase.

(a) VOLTAGE DIFFERENCE (Same Phue)

v

(b) PHASE DIFFERENCE (Lmc Voltage)

Figure 2: Voltage And Phase Dlfference In Figure 2(a) the two voltages VA and VB are in phase with one another, but their amplitudes are different. At any instant such as time T, the instantaneous voltage of machine 'A' is TA and that of machine '6' is TB. Therefore there is, at that instant, a voltage difference A6 which will cause a circulating current to flow between the generators when the paraiieling switch is closed. This is true at any instant other than a common voltage zero. In Figure 2(b) the two voltages have equal amplitudes but are displaced in phase, VB lagging on VA .At any instant such as time T the instantaneous voltage of machine 'A' is TA and that of machine 'B' is TB. Although the two voltages are equal in amplitude, there is still an instantaneous difference of voltage A6 which will cause a circulating current to flow between the generators when the paralleling switch is closed. Therefore, even though the voltage leveis'(as read by voltmeters) are the same, a difference of phase will still cause a circulating, or 'synchronising', current to flow between the machines, causing one to accelerate and the other to decelerate and to jerk them into phase with each other as the switch is closed. Therefore, to prevent sudden circulating currents occurring and to achieve smooth paraiieling, the voltages of both machines must first be equaiised and the machines then brought into phase. This is described in the following section.

02.01 (A) Synchronising.doc


1

SYNCHRONISING

#

k

I=

There is one further requirement. As when changing gear in a car, the two generator speeds must alsc be equalised before paralleling. If this is not done, the faster machine will be jerked back and the slowel jerked forward, which could cause serious mechanical problems in large machines, as well as to the couplings, gear trains and prime movers. If the two machines are running at different speeds before paralleling, this will show as differen, frequencies on the frequency meters. Therefore a preliminary to synchronising is to equalise as nearl) as possible not only the machine voltages but also their frequencies, using the switchboard voltmeters and frequency meters. The following conditions must be equal before closing the circuit breaker: D Voltage D ~re~iency D Phase D Phase Rotation In some situations it may be preferable to have the generator being synchronised running sllghtly fasl (super-synchronous) at the moment of circuit breaker closure so that power flows from the prime mover into the busbars. Conversely, it may be preferable to have the generator being synchronised running sllghtly slow (sub. synchronous) at the moment of circuit breaker closure so that power flows from the busbars into the prime mover. This may however cause the generator 'reverse power' protection system to operate. b 4

SYNCHRONISING AC GENERATORS It is assumed that one machine' A ' (the 'running' generator) is already in service on the busbars and is on load, and that a second machine '6'(the 'incoming' generator) has been started and run up and is ready to be put in parallel with 'A' in order to share its load. Before this can be done the incoming generator '6' must be synchronised with the running machine 'A'. As already described, the first step is to match the incoming to the running voltage by,reference to the voltmeters on the two generator control boards, and by using the inwming voltage regulator to trim it. Similarly the incoming frequency Is matched to the running frequency by reference to the two frequency meters and by trimming the inwming speed regulator. Note that the running machine controls should not be touched -the incoming machine is always matched to the running, not vice versa. It now remains to bring the generators into phase. Even aeifr matching the frequencies by meter, the speeds will still not be exactly equal, and one machine will be slowly overtaking the other. As this occurs, their phase relationship will be steadily, but slowly, changing. The idea is to make this take place as slowly as possible and, as they momentarily pass through the 'in-phase' state, to catch them at that point, to close the paralleling switch and to lock them there.

-

There are two ways in which the correct phase may be detected the first is by lamps, and the other is by an instrument called a synchroscope. b

04.02.01 (A) Synchronising.doc

0 Brush Electrical Machines Lld. 2003

15

I

I

LAMP SYNCHRONISING The 2- lam^ Method

Synchronising

Figure 3: Lamp Synchronising (%Lamp Method) Synchronising by lamps makes use of the circuit shown in Figure 3; two lamps in series are connected across the same phase of each generator. Only when the two systems are in phase is the voltage across the lamps continuously zero, and both lamps are out. At all other times there is a voltage difference, and the iamps glow. This is known as the 'lamps dark' method of synchronising. The voltage phase vectors of both generators are shown. Machine No 1 is the 'running' and its vectors are in full line. Machine No 2 is the 'incoming' and its vectors are dotted. It is approaching synchronism with No I. When the machine frequencies are nearly equal, the iamps are switched on and alternately glow and go out, giving a slow flashing appearance. The nearer the frequencies are to being equal, the slower the lamp flashing period. Th.erefore to achieve phase matching, the incoming machine's speed is slowly trimmed until the lamps are flashing very slowly; then, as they are changing from bright to dark, the operator places his hand over the breaker control button or handle and, at the moment when the lamps go completely out, operates it to close the breaker. The lamps then stay out, but they should be switched off afler completing the synchronising.


@ Brush Electrical Machines Lld. 2003

I

li-r.,

SYNcHRoNlslNG -BRUSH

B E M Ltd.-


I

Issue A

I

.. .

Date Apr112003

...

Page 7 o f 10

Note: The lamps could be connected to burn at their brightest, instead of being dark, wher the systems are in phase, but this 'lamps bright' method is seldom used today. It is easier tc detect the exact point of 'no light' in a lamp than to estimate when it is at its brightest. The 'lamps dark' method is almost universally found. It is necessary to use two lamps in series because, when the systems are fully out of phasc (lamps at brightest), the voltage difference is then double the system phase voltage. b 5.2

The 3- lam^ Method

Gen 'B'

Gen ' A ' (~unning)

(Incoming)

Lamp 2

Lamp 1 (Y, -Y1) out

(BI-RI) out

Lamp 3

I

( R , -B, Out

Flgure 4: Lamp Synchronising (3-Lamp Method) An alternative method, known as '3-lamp synchronising' can also be used. It is shown ir Figure 4. The three lamps are connected as shown: No.1 (yellow-to-yellow)l No.2 (blue-to-red) and No.3 (red-to-blue). In the centre diagram the full lines refer to generator 'A' (R,, Y, and B,), and the dotted lines to generator '6'(R2, Y2 and B2). Machine '6'is shown approaching synchronism with machine' A '. W i h the lamps so connected, the voltage a c r o s s ~ o . 1lamp (Y, - Y2) is small, and the lamp glows dimly. The voltages across No.2 and No.3 lamps (B, R2 and R, B2) are large, and both lamps are bright. As synchronism is reached (left-hand of the three lowest diagrams: No.1 lamp goes out and the other two have equal brightness.

-

-

When the two generators are 120' out of synchronism (centre of the three diagrams) it can be seen that it is No.2 lamp (B, R2) which has no voltage and goes out. 120' later (right hanc diagram) No.3 lamp (R, B2) goes out.

-


-

Q Bmsh Electrical Machines Ltd. 200:

---- - -.

. -

-

--

SYNCHRONISING

Thus, as generator '6'catches up with generator 'A', each lamp goes out in turn, and at a decreasing rate, as synchronism is approached. Finally, at synchronism, No.1 lamp remains extinguished long enough for the generator breaker to be closed.

1

The lamps are arranged either in a triangle with No.1 at the top, or in a line with No.1 in the centre. They may be lettered 'A', 'B' and 'C' instead of being numbered. Depending on whether the order of going out is clockwise or anti-clockwise with the triangular arrangement, or left-to-right or right-to-left with the inline arrangement, the operator can deter-mine whether the incoming generator ,is fast or slow - which cannot be done with the 2-lamp method. b 6

I

SYNCHROSCOPE

Q SYNCHROSCOPE

Figure 5: Synchroscope A typical synchroscope is shown in Figure 5. It is an instrument with a movement similar to that of a power factor meter, but with the two windings fed from the running and incoming voltages. Whereas in a power factor meter the currentlvoltage phase relationship is fixed and the pointer is stationary, in a synchroscope the phase relationship between the two voltages is constantly changing and the pointer rotates continuously, the direction of movement depending on whether the incoming machine is rotating faster or slower than the running. The face is marked with arrows denoting FAST or SLOW; these terms always refer to the incoming generator. When the pointer passes through the 12 o'clock position, the machines are momentarily in phase. {Some synchroscopes are marked '+' and '-': The plus sign corresponds to FAST and the minus to SLOW). Standard specifications often require lamp back-up to the synchroscope. Many early synchroscopes are short time rated, and it is necessary to switch off these units when the synchronising operation has been completed.

7

SYNCHRONISING AT THE SWITCHBOARDICONTROL PANEL Most switchboardslcontrol panels control two or more generators, and some systems have section breakers or interconnectors to other generator systems, anyone of which may have to be synchronised with running machines. It would not be economic to have a separate synchroscope for each one, as it is used only infrequently. Common practice is therefore to have one synchroscope (sometimes with back-up lamps) in a central or conspicuous position on or near the switchboard/control panel together with selector switches whereby any chosen machine may be made the 'Incomer'. Selection may be by manual switch, key or plug. The running side is usually taken from the busbar. Where the switchboard handles high voltage the incoming and running voltage signals are taken through voltage transformers. The synchroscope is normally provided with fuses and an isolating switch, as it is not good practice to leave it in circuit when it is not in use.



- -- - -. - 7----

-

SYNCHRONISING

..

Training Module: To use the synchroscope, having selected which is to be the incoming generator, the voltages and frequencies are first matched as already described in Section 4. The synchroscope is then switched on; its pointer will be rotating. The incoming speed regulator is trimmed until the pointer is moving very slowly in the FAST direction. As it next approaches the 12 o'clock position, the hand is placed over the breaker control button or handle and, just before the pointer reaches 12 o'clock, it is operated to close the breaker. The synchroscope will then stop and remain locked in the 12 o'clock position as the generators remain in synchronism. Finally, the synchroscope should be switched off. The reason why the incoming generator should be running the faster is that, when the breaker is closed, it will immediately take up a small part of the load. If it were running slower, that load would be negative - that is, the machine would 'motor' - and a reverse power situation would exist. The generator's reverse power protection might then cause the breaker to trip. F

8

AUTOMATIC SYNCHRONISING It is common for switchboards1control panels to be provided with an automatic synchronising feature. The automatic synchroniser compare the incoming and running voltages and frequencies as well as their phase relation. Should any of these be outside limits, the incoming voltage regulator or speed regulator is automatically trimmed. Only when all three are within predetermined limits is a signal given automatically to the circuit breaker to close. Here again there is usually only one auto-synchronising unit to each switchboard; it is connected automatically to whichever machine is being started so long as the synchronising selector switch is set to AUTO.

-

Auto-synchronising is usually resewed for generators only. All other synchronising for example across section breakers or interconnectors or on L V switchboards is normally by hand.

-

9

CHECK SYNCHRONISING In many instances, particularly with smaller generators and in the cases just mentioned, automatic synchronising is not used, and the exercise must be carried out manually by lamp or synchroscope. In such cases there is a danger that, if the manual synchronising is carried out unskilfully.'the switch could be closed at the wrong instant and severe damage could result to expensive machinery. This can be prevented by 'check synchronising'. The equipment is similar to that used for autosynchronising, but it does not automatically trim the incoming voltage, frequency and phase it only monitors them. Nor does it carry out the final act of closing the circuit breaker automatically; these all have to be done manually by the operator. However it does inhibit the breaker's manual closing circuit so that, unless all three synchronising conditions are satisfied together, the operator cannot close the breaker even though he presses the CLOSE button. If the breaker then fails to close, the whole synchronising process must be repeated.

-

Some check synchronising units sense only phase angle difference and do not monitor voltage or frequency differences. They rely on manual adjustment of voltage and frequency and only inhibit the closing of the breaker when the phase angle difference is excessive. It should be noted that voltage difference will cause circulating reactive current only. Although this is not desirable, it does not cause any mechanical shock and consequent damage to the transmission or the turbine since no active power is involved. When, and only when, the check synchroniser is satisfied that the voltages, frequencies and phase difference are within acceptable limits (or, in the case of the 'phase only' type, that the phase difference is within limits), it closes a contact which 'arms' the circuit-breaker closing circuit, so permitting closure when the operator presses the CLOSE switch. The same contact on the check synchroniser can also momentarily light an IN SYNCHRONISM or READY TO SYNCHRONISE lamp, indicating to the operator that the breaker is ready for closing. Once this lamp has gone out again, he cannot close the breaker until it illuminates a second time.



BRUSii] -BRUSH

B E M Ltd.-

1


SYN~HRONISING

I

Issue: A

1

Date: Aprll 2003

I

Page.IOof10

Where check synchronising is fitted, it is brought automatically into circuit whenever a second or subsequent generator has been started and selected for switching on-line; it so serves as a protection against incorrect operation. Check synchronisers may also be fitted across section breakers, interconnectors and L V incomers from transformers - in fact at any point in the network where it might be possible to close across two unsynchronised systems accidentally. They are also fitted across main generator incomer breakers even when auto-synchronising is provided. They are usually arranged to come into action automatically if manual synchronising is selected. Sometimes operators form the bad habit of holding the breaker control switch closed before synchronism is reached, and relying on the arming contact of the check synchroniser to complete the closing circuit. This is bad practice and must be avoided. 10

CLOSING ONTO DEAD BUSBAR If it is required to connect an incoming generator, or L V transformer incomer, onto a dead busbar, the check synchroniser will not allow it to happen because, one side being dead, the two sides can never be in synchronism. In that case the check synchroniser must be temporarily 'cheated' while the connection is made. On most switchboards/control panels a special switch is provided for this purpose. It is spring-loaded to return to the OFF position so that the check synchroniser cannot be left permanently out of operation. This cheating switch may be tagged CLOSE ONTO DEAD BUSBAR or CHECK SYNC. OVERRIDE or other similar wording. b

CAPABILITY DIAGRAMS -BRUSH

B E M Ltd.-


I

Issue A

I

Page 1 of 10

Date Apr112003

CAPABILITY DIAGRAMS Theoretical stability limit Practical

MW

I; .-----4

\

\

I .

MVAr (Leading)

E T

0

Q

MVAr (Lagging)

e CAPABILITY DIAGRAMS -BRUSH

B E M Ltd.-


I

Issue. A

I

lj-

Date: April 2003

...... Page: 2 of 10

CONTENTS I INTRODUCTION ...................................................................................................................................... 2 STATOR CURRENT .................................................................................................................................. 3 POWER OUTPUT ...................................................................................................................................... 4 ROTOR CURRENT .................................................................................................................................. 5 STABILITY OF THE ROTOR ..................................................................................................................... 6 TEMPORARY LIMITATION ....................................................................................................................... 7 USE OF THE CAPABILITY DIAGRAM ..................................................................................................... 8 CAPABILITY DIAGRAM FOR SYNCHRONOUS MOTOR ........................................... :........................... 9 CAPABILITY DIAGRAM FOR SYNCHRONOUS CONDENSER .............................................................

04.03.01 (A) Capability Diagrarns.doc

B Brush Electrical Machines Ltd. 2003

rule: 04.03.01

1

I

1

I

Issue: A

I

ate: April 2003

Page: 3% 10

INTRODUCTION The principal limitations on the output of a generator are as follows: > Current heating of the stator (armature). 9 Power Output of the prime mover. > Current heating of the rotor (field). 9 Stability of the rotor angle.

1(

There are other limitations such as the heating due to iron losses, harmonic currents, negative and zerc sequence currents, etc., but the four listed above have the most decisive limiting effect. 2

STATOR CURRENT Consider first the stator. The I'R, or 'coppet, losses due to the load current are, together with the iron losses, the main sources of stator heating. With a given cooling system there is clearly an upper limit to such continuous stator currents no matter what their power factor may be. Stated another way, there is a limit of MVA beyond which the generator must not be allowed to go continuously, and this limit applies al all power factors.

MW I

MVAr

0

(Leading)

B N

MVAr (Lagging)

Figure I In Figure 1, if the reactive (MVAr lagging) loading is taken as the x-axis and the active (MW) loading as the y-axis, then for any given loading P (PN being the active component and PM the reactive), the line OP represents the MVA of that load (= JPN' + PM'), and the angle POM is the phase angle of the load. If a semi-circle is drawn about the origin 0 and with radius equal to the maximum permitted MVA, then only those loads (such as P) within that semicircle are within the capacity of the generator. This is the first limitation. POWER OUTPUT The electrical MW rating of an engine driven generating set is limited by the mechanical output of the prime mover. Therefore, if a horizontal line is drawn across the MW axis at a level equal to the maximum output of the prime mover (OA), the top part of the semicircle is cut off, since it represents MW power which is not attainable from the engine. Therefore the loading of the generator must be confined to points within the remainder of the semicircle. This is the second limitation and is shown in Figure 1 as a dotted line. C

04.03.01 (A) Capability Diagrams.doc

@ Bmsh

Electrical Machines Ltd. 2003

CAPABILITY DIAGRAMS

4

ROTOR CURRENT To achieve the rated MVA loading or, a certain level of excitation is required. This calls for a certain rotor current, with its consequent I ~ R losses which cause rotor heating. The cooling system takes this, together with the stator heater heating, into account. Any increase in excitation beyond this level - and hence in rotor current - will cause rotor overheating; so at first sight the load point P should remain to the left of the line RE. -

-

MW /---\

/

A

'\R

\

Max MW output o f prime mover

\

Rotor heating

-limit

\

\

I,

MVAr (Leading)

E

0

B

Q

MVAr (Lagging)

Figure 2 However, there is a point E* on the other side of the origin such that the line ER represents the emf of the generator when operating at its rated load and power factor. ER then represents not only the emf but also the excitation and so the rotor current needed to produce it. Constant excitation at various maximum loads and power factors is therefore represented by an arc of a circle through R, centre E, shown by the arc RQ in Figure 2. This arc this represents the maximum allowable rotor current at different maximum loads and power factors. To avoid overheating the rotor, therefore, the load point must lie to the left of the arc RQ (not to the leff of line RB as first suggested above) This is the third limitation.

-

-

Note: 'Though not strictly necessary to know for the purpose of this explanation, the posltion of point E is determined from the generators synchronous reactance. If this is n per unit (= percenUlOO), then the length OE is l l n times the radius of the semicircle. Thus if n = 200% (fairly typical), E is halfway between 0 and the circumference. b 5

STABILITY OF THE ROTOR When the machine is generating, the rotor is driven ahead of the stators rotating magnetic field at an angle depending on the actual active load it is called the 'Power Angle', symbol A. The opposing torque developed by the generator on the engine is due to the magnetic back-pull on the rotors poles by the stators magnetic field. The greater the power angle, the greater the back torque. The driving torque delivered by the engine is just balanced by this back torque from the rotor, and the rotor is stable.

-

When the loading is lagging reactive, armature reaction in the stator causes the field poles to become partly demagnetised. The consequent loss of air-gap flux reduces the net emf and so the terminal voltage; this is detected by the AVR, which causes increased excitationto restore the air gap flux and so the emf. W l h leading reactive loading the opposite effect occurs. The leading stator current causes the field poles to become more magnetised at first. The gain of air-gap flux increases the net emf and so the terminal voltage; this is detected by the AVR, which then decrease excitation to restore the air-gap flux.

04.03.01 (A) Capability 0iagrams.doc


I

CAPABILITY DIAGRAMS Page:5gl,!OIf this process were allowed to continue and the leading load to increase further, the point would be reached where the excitation of the rotor poles would be reduced to nothing, and all the air-gap flux would be provided by the stator alone. There would then be no rotor poles upon which the stator could pull back. The prime mover would drive the rotor ahead out of synchronism, and the generator would go unstable, pulling out of step. This situation would occur if the reactive loading reached a value equal to OE (leading), since at E the excitation is reduced to zero. Therefore the load point P must never be allowed to go to the left of the vertical line through E -that is, the leading MVAr must never be allowed to exceed the value OE. This is the fourth limitation and is shown in Figure 3.

Theoretical stability limit \ Practical

MW I

\

\

MVAr (Leading)

E T

0

Q

-

MVAr (Lagging)

Figure 3 Clearly such a limitation must never be allowed to occur or even to be approached, as the generator would become difficult to control. There is therefore a limit to the amount of leading current (or MVA) which a generator may be allowed to produce. The theoretical limit set in the previous paragraph is therefore in practise too high. The practical limit will be appreciably less and is represented by the dotted curve ST in Figure 3; the calculation of this curve is complicated, and it is merely indicated here. Its shape will depend on whether the rotor is cylindrical or has salient poles. in practise, however, leading loads on platforms should never arise. So in Figure 3 the theoretical semicircle inside which the loading of the generator must lie is limited at the top and now at both sides, and the only 'usable' part is the coloured area if the generator is to run within its rating and remain stable. The coloured part of Figure 3 is called the 'Capability Diagram' of that generator set. It provides a constant guide not only on the loaded state of the generator but also on its maximum allowable further loading. It shows whether any intended additional loading will still remain within, or go outside of, the rating of the generator set, and it therefore indicates whether or not s further machine should be started up. All that is required to determine the existing load point on the capability diagram are the generator MW and MVAr instrument readings. b 6

TEMPORARY LIMITATION A special case arises when large motors are to be started. They impose a large, but temporary, reactive loading while starting, which fails to a much smaller value when run up to speed. The extra excitation needed for this can if necessary be found from the AVR's field forcing circuits, which provide extra field current above the normal maximum. This, although above the steady current limit of the rotor windings (arc RQ), may be tolerated for a short time without damaging the rotor.



CAPABILITY DIAGRAMS

-BRUSH B E M Ltd.Training Module: 04.03.01

I

Issue A

1

Date Apr112003

Page 6 o f 10

For this reason capability diagrams are sometimes furnished with one or more additionai rotor current limitation arcs with a specified time limit of, for example, 30 seconds, as shown in Figure 4. This means that, within this time, the reactive loading may be increased to the indicated higher limit to allow the motor to start, provided that it falls back to within normal limits within the specified time when the motor has run up to its steady speed. On some systems, if the rotor current goes beyond the higher limit, or if it fails to return to within normal limits within the specified time, the generator is tripped.

MW I

i

/c---

--f

---

/

S A

Rotor heating temporary limit

\

for30 seconds

/'

-

i

I

MVAr

E T

0

(Leading)

Q

MVAr (Lagging)

Flgure 4 If the total reactive load on starting falls outside even this higher temporary limit and automatic tripping is not fitted, it goes beyond the field forcing limit of the AVR, and a prolonged dip of the system voltage will result, besides risking damage to the rotor. b USE OF THE CAPABILITY DIAGRAM To use the capability diagram, the Operator looks at the wattmeter and varmeter of the generator which is to be further loaded and he plots the point P on the diagram corresponding to the MVAr and MW standing load readings see Figure 5. He notes, or calculates, the additional load in the MVAr and MW which he intends to put on top the generator ; these he adds to the MVAr and MW values of the point P. If the resulting point PI lies within the coloured area, the generator can accept the additional lad. If not, he must be prepared to start an additional load. If not, he must be prepared to start an additionai generator to share the total load. If the excess is marginal, he must use his discretion.

I

I

Flgure 5

I

3.01

Issue: A

1

Date: April 2003

1

Page: 7 of 10

Particular care is needed if a large motor is to be started. Although the additional MVAr and MW at ful load may be acceptable to the generator, the MVAr due to the large starting current may not. FOI example, a certain gas export compressor motor has an input of 5MW at 0.85 PF, giving a full ioac demand of 2.6 MVAr and 5.OMW, which might be acceptable on top of the standing load. But the startin< current is approximately 1500A at 0.25 PF, giving a starting demand of about 25MVAr and 7MW. While even the 7MW might be acceptable to the generator, the capability diagram would show that the additional 25 MVAr on the starting almost certainly would not be, even taking into account any temporar) margin allowed. The operator would need to put on line extra generators to accommodate this start, ever if he took them off again once the motor had run up. The following illustrates this point with a differenl motor. When a second generator is put on line, it is assumed that both share the load equally; therefore the MW and MVAr loadings on each are half what they were with one generator only. This means that the 'workins point' P has half the previous values and is therefore much nearer the centre. This leaves more room f o ~ additional loading, remembering also that the additional load itself on each generator is also halved. b

Example A 6.6kV generator is rated 15MW at 0.85PF. At a certain moment it is carrying a standing load of 8MW and 6 MVAr (represented by point P in Figure 5) as given by its switchboard instruments. It is desired tc start and run a 3600kWm. 0.8PF water injection motor (efficiency 96%) on this generator. The motors starting current is four times full load current at 0.25PF. The capability diagram, including the temporar) limitation curve is given in Figure 5. Can this generator carry the extra load, and can the motor be started on it? If not, what action should be taken? (In the following calculations all results have generally been rounded off to the nearest 10 units Operations at a generated voltage of 6.8kV has been assumed).

Generator Generator rating 15MW at 0.85pF and 6.6kV (6.8kV operation) (15MW) Full-load current (I) =

15000 = 1500 d3 x 6.8 x 0.85

cos @ = 0.85, :.sin @=0.53 Full-load reactive power = d3 x kV x I x sin @ = 43 x 6.8 x 1500 x 0.53 = 9360 (say 9.4 MVAr)

Motor (Running) Motors output is 3600kWmat 0.9 efficiency; Motor input is 3600 = 4000kW. at 0.8pF (4.0MWe) 0.9

4000 = 425A Full-load current (IF,) = 43 x 6.8 x 0.8 Full-load reactive power = d3 x kV x IF, x sin 0 = d3 x 6.8 x 425 x 0.6 = 3000KVAr (3.0MVAr)

Motor (Starting) Starting current (Is,) = 4 x full-load running current (IFL)= 4 x 425 = 1700A at 0.25pF

- -4 0 3 01 (A) Capabllly Diagrams aoc --

--

-

--- --

-- @

Brush Eleclnca, Machlnes Lla 200:

ff

CAPABILITY DIAGRAMS -BRUSH

B E M Ltd.-


I

I

Issue: A

Date: April 2003

Page: 8 of 10

Starting active power = 63 x kV x ISTx cos 0 = 63 x 6.8 x 1700 x 0.25 = 5010KW, (say 5.OMW.) and starting reactive power = 43 x kV x lsr x sin 0 = 63 x 6.8 x 1700 x 0.968 = 19380KVAr (say 19.4MVAr) Combination When running: standing load is 8.OMW 8 6.OMVAr motor load is 4.OMW & 3.0MVAr Total: I2.0MW 8 9.0MVAr Plotted on the capability diagram, this gives point P, which is well within the coloured diagram limits and is therefore acceptable. When starting: standing load is 8.OMW B 6.OMVAr motor load is 5.OMW & 19.4MVAr Total: 13.OMW 8 25.4MVAr Plotted on the capability diagram, this gives point P2,which lies outside the diagram and even beyond the temporary limit. The starting of this motor is therefore not acceptable, even though the current could be carried continuously once running. Before starting, therefore, either the standing load must be sufficiently reduced or another generator set must be started and put on-line. b CAPABILITY DIAGRAM FOR SYNCHRONOUS MOTOR Although the capability diagram so far described takes the form of a semicircle, it can be continued below the horizontal axis to become a complete circle. In that case the y-axis, representing active power (or MW), is negative and so indicates negative active power supplied by the machine. This is equivalent to active power being received by the machine; that is to say, the machine is absorbing true power and is therefore motoring. The x-axis, representing lagging or leading machine power supplied, is not affected.

Rotor heating MVA limit Stator heating MVA lim

MW (Matoring) Figure 6

.03.01 (A) Capabiliw Diagrams.doc

0 E ~ s Electrical h Machines Ltd. 2003

C CAPABILITY DIAGRAMS -BRUSH

6 E M Ltd.-


I

I

Issue. A

Date. Apr~l2003

Page: 9 of 10

The two lower quadrants shown in Figure 6 thus represent the machine operating as a motor - that is, as a synchronous motor. The left-hand lower quadrant indicates such a motor running under excited and therefore supplying some leading VAr's to the system, equivalent to drawing lagging VAr's from it. The right hand lower quadrant indicates a motor well excited and supplying lagging VAr's to the system equivalent to drawing leading VAr's from it.

-

It should be noted that the excitation can be adjusted so that the machine is drawing neither leading no1 lagging VAr's (point Q) - that is, it is taking no reactive power at all, only active power. Such a motor is then running at unity power factor - a useful feature of the synchronous motor. It is possible to go even further. The machine can be deliberately run as a motor overexcited i.e, in the fourth quadrant where it will draw active power from the system as it motors, but it will at the same time supply lagging VAr's, and it will therefore run at a leading power factor. If a mixed load of induction motors and a large synchronous motor is installed, the synchronous motor run in this manner can help compensate for the poorer power factors of the induction motors.

-

Below the horizontal the prime mover output limitation clearly no longer applies, but the rotor and stability limitations apply as before. The 'working point' P must therefore fall within the coloured area of Figure 6 if the motor is to work within its design limits. When determing the working point P, all losses (including friction and windage losses) must be added ta the known mechanical power of the motor drive, since all go into the total power absorbed. The losses can be calculated from the efficiency of the motor at that particular loading. There are no synchronous motor drives in offshore or onshore installations, but they are used elsewhere onshore in larger plants where exact constant speed operation is required. F CAPABILITY DIAGRAM FOR SYNCHRONOUS CONDENSER A synchronous motor, whenever excited, can be used as if it were a bank of static capacitors.

MW (Generating)

MVAr (lead7

MVAr

E

0

p%iGq

QL -(lag) Variable

Figure 7 Figure 7 represents the capability diagram of such a synchronous machine. The full semi-circle above the line depicts its generation mode, as discussed previously. The y-axis represents generated active powel (MW). If extended downwards it represents negative active power - that is, motoring instead of generated power. The x-axis to the right represents lagging reactive power (MVAr) given out by the machine whethel generating or motoring and is associated with the degree of excitation.


0 Brush Electrical Machines Ltd. 200:

El I

CAPABILITY DIAGRAMS

*A

I=

Imagine such a machine used as a generator and driven up to speed by its prime mover an( synchronised onto the system, where it takes up its share of the active and reactive loads. The workin( point of the capability diagram of Figure 7 would be, say. P. Suppose then that the prime mover i! unclutched, or that its fuel is cut off, but that the machine is well excited and its excitation remain! unchanged. Mechanical drive to the machine then ceases, but it continues to rotate in synchronism wit1 the system. It draws from the system only enough active power to keep itself going without driving an! external load - it behaves as an unloaded motor, drawing just enough active power to make good it: losses - a 'reverse power' situation. Plotted on the capability diagram of Figure 7, the working point woulc now be Q, with slightly negative MW but delivering rather more lagging MVAr as before due to it: unaltered excitation. Such a machine would then be supplying reactive lagging power (megaVAh) but no active powel (megawatts). Supplying lagging VAts is the same thing as receiving leading VAr's, since one is thc negative of the other. Therefore a machine operating as described above can be regarded as drawinc leading reactive power that is to say, it behaves as a static capacitor. The machine is then called z 'synchronous capacitor', although the old name 'synchronous condenser' remains in common use.

-

Moreover, the amount of leading reactive power drawn will be determined by the degree of over. excitation. Therefore the 'capacitance' is infinitely variable as required by the changing system loac conditions, unlike that of a bank of static capacitors which can only be switched. If a synchronous condenser is not available to correct the power factor of a system, a corresponding effecl can be obtained by running any synchronous motors in the system in an over excited state. In this condition they will draw leading reactive current in addition to their active current. This will compensate f o ~ the large lagging currents drawn by many induction motors by providing a useful contribution to the lagging VAr's needed by those motors instead of calling on the generators to do so. b

1.03.01 (A) Capabilily Diagrams.doc


1I

CONNECTION OF GENERATING PLANT

L

I

C

CONNECTION OF GENERATING PLANT Ref. NO-. 1

OWNERSICOMPANY DETAILS

I

Name and Address

Telephone Nurnbar(s) 2

GENERATING PLANT DETAILS

I

~ocsuon of Generator

Manufacturer

,.... ......... ~~

....,...

.......

...,.,..................,.., ~

~

..................

~

............................ ......... ....... ~~

I

R a t d Vollage Fnquew CapacMy(kVA) cunsnt POW, Factor 3

ELECTRICITY BOARD SUPPLY DETAlLS vollage a m i c e Details Capacily (kVA) Maxlrnurn Fault Level PdntofCornrnonCoupllng Prolscllon

I

:ONTENTS I INTRODUCTION........................................................................................................................................ 3 ! G59 RECOMMENDATIONS FOR THE CONNECTION OF GENERATING PLANT ...............................3 2.1 Introduction a 2.2 Definition 2 2.3 Legal Aspect E 2.4 Connection Arrangements ........................ ........................................................................................ 5 2.5 System Earthing (Grounding) Aspects ..................... ............................................................... 6 2.5.1 HV System ....................... . . . ..................................................................................................6 2.5.2 LV System .............................................................................................................................. 6 2.6 Parallel Operation With The Electricity Board's System (Including Occasional Paralleling) ..............7 2.6.1 Operational And Safety Aspects ............................. . . ............................................................ 7 2.6.2 Technical Considerations........................................................................................................... 8 2.6.3 Control Equipment Requirements.................. ..................................................................... 9 2.6.4 Protective Equipment............ . ................................................................................................ 10 2.6.5 Power Factor Correction ............................................................................................................ 11 2.6.6 Testing And Commissioning ............................. . ..................................................................... 11 Metering .................... . ...........................................................................................................12 2.6.7 2.7 Operation With Alternative Connection To The Electricity Board's System ..................................... 12 2.8 Private Generation Test Record................ . .................................................................................... 13

............

.........

.05.01 (A) Connection Of Generating Plant.doc


-BRUSH

B E M Lid.-

1

Training Module: 04.05.01 I


I

Issue: A

1

* Ii-

Date: April 2003

..

...

Page: 3 of 14

INTRODUCTION With increasing numbers of factories and utilities generating power into the national electricity grid network, it is often considered necessary by the relevant authorities to introduce regulations to regulate these power providers. These regulations are designed to protect both the power providers' and distributors' electrical equipment should an electrical fault develop on either system. Much of the regulations covers switchgear protection which disconnects the distributor should a fault occur. Usually the main protection relay is the rate of change of frequency relay, often referred to as ROCOF relay, which detects that the system has become detached from the grid network. This relay will normally trip the grid feeder to the utility should the grid supply deviate out of preset timed frequency limits. It will only be allowed to trip this breaker should generators be on line at the instant the relay operates. The relay is used in conjunction with under and ovelvoltage relays. This will prevent crash synchronising of systems when the grid supply returns. Later versions of this relay detect distortion on the supply lines caused by diesel piston power strokes thus indicating the station has become disconnected from the grid network. In the United Kingdom G59 Recommendations For Connection Of Private Generating Plant to The Electricity Boards' Distribution Systems were introduced in June 1985 by the UK Electricity Council's System Development Consultancy Group. G59 Recommendations provide a good indication of the principles involved, hence a summary is provided hereafter for information (clause numbers do not correspond with actual G59 clause numbers). Note: It should also be appreciated that local regulations i n other parts o f the world may differ. b

2

G59 RECOMMENDATIONS FOR THE CONNECTION OF GENERATING PLANT 2.1

Introduction Recommendations relate to the wnnection of privately owned generators and generating systems to UK Regional Electricity Boards' distribution systems and is intended for use where the connection is to be made to Boards' systems at, or below, 20 kV and where the output of the generator system does not exceed SMW. The wnnection of generator systems of larger capacity and at higher voltages, will normally require a more stringent technical appraisal and consideration Such generating plant is therefore outside the scope of these recommendations, although similar principles will still apply. The document applies to systems where the private generating plant may be paralleled with the Boards' distribution systems or where either the private generating plant or the Electricity Boards' systems may be used to supply the same electrical load. Throughout the document. the term 'private generator' includes 'private generators or suppliers' as defined in Section 2.2.

2.2

Definitions Private Generator o r Supplier A person, other than an Electricity Board, who generates electricity or supplies electricity generated otherwise than by an Electricity Board. ,. Low Voltage (LV) A voltage not exceeding 1000 volts. High Voltage (HV) A voltage exceeding 1000 volts. Electricity Board's Control Englneer The Control Engineer at the Electricity Board's Control Centre.

04.05.01 (A) Connection Of Generating Plant.doc

Q Brush Electrical Machines Lld. 2W3

BRUSIHI I

-BRUSH

B E M Ltd.-

I



I

Issue: A

I

I1.

Date: April 2003

I=&!

I

Page: 4 of 14

Point Of Common Coupling The point on the Electricity Board's network, electrically nearest the generating plan installation, at which other consumers' loads are, or may be, connected. Point Of Supply The point of electrical connection between the apparatus owned by the Electricity Board ant the apparatus owned by a Private Generator. Plant Types Definitions of types of generating plant are given below; other types of plant may be suitable. a) Synchronous Generator A type of rotating electrical generator which operates at a speed that is directly related tc system frequency. The machine is designed to be capable of operation in isolation from other generating plant. The output voltage, frequency and power factor are determined b) control equipment associated with the generator. Under certain conditions, the synchronous generator may be paralleled with a network containing other generation. On disconnection of the paralleled connection, the synchronous generator will continue tc generate at a voltage and frequency determined by its control equipment. b) Mains-Excited Asynchronous Generator A type of rotating electrical generator which operates at a speed not directly related ta system frequency. The machine is designed to be operated in parallel with a network containing other generation. The machine is excited by reactive power drawn only from the network to which it is connected. The output voltage and frequency are determined by those of the system to which it is connected. On disconnection of the parallel connection, the mains excited asynchronous generator will cease generation. c) Power Factor Corrected Asynchronous Generator A derivative of the mains-excited asynchronous generator where the machine is excited partly by the network to which it is connected and partly by a device of fixed capacitance connected locally to the machine. On disconnection of the parallel connection, the power factor, corrected asynchronous generator may continue to generate electrical power at a voltage and a frequency determined by the machine and system characteristics. d) Self-Excited Asynchronous Generator A derivative of the mains-excited asynchronous generator where the machine is excited purely by a device of variable capacitance wnnected locally to the machine. The machine is capable of operation in isolation from a network containing other generation and in this respect is similar to the synchronous generator. Under certain conditions, the self-excited asynchronous generator may be operated in parallel with other generation, and on failure of that connection, the machine will continue to generate at a voltage and frequency determined by its control equipment. e) Self Commutated Static lnvertor An electronic device to convert direct current (d.c.) to alternating current (a.c.) in which the output value of a.c. frequency and voltage is determined by control equipment associated with the device. It is similar to the rotating synchronous generator in that, under certain conditions, it may be wnnected in parallel with a network containing other generators. On failure of that connection, the device will continue to provide power at a voltage and frequency determined by its control equipment. f) Line Commutated Static lnvertor A derivative of the self commutated static invertor where the output a.c. frequency and voltage are determined by the network containing other generation to which it must be connected. On disconnection of the parallel connection, the line commutated static invertor will normally cease generation. b

..05.01 (A) Connection Of Generating Plant.doc

B Brush Electrical Machines Ltd. 2W3

A-


1

According to various Acts Of Parliament Electricity Boards are not compelled to supply any premises unless it is reasonably satisfied that the electric lines, plant, fittings and apparatus on those premises are in good order and condition and are - not calculated to affect injuriously the use of energy by the Board or any other person. Electrical includes -a private generator's plant. Boards may discontinue supplies if the use of such plant interferes unduly or improperly with the efficient supply of energy to other persons by the Board. There is a statutory obligation an the Electricity Boards to maintain the safety and quality of electricity supply within defined limits. The conditions governing the connection of an installation to the Board's electricity supply network are contained in various Regulations, and a private generator must not operate his plant in such a way that the Electricity Board is unable to fulfil its obligations under these Regulations. An Electricity Board has a statutory obligation to offer, at the request of a private generator: a) to give and continue to give a supply of electricity to premises where he generates electricity, or from which he supplies electricity to others, or b) to purchase electricity generated by him, or c) to permit him to use the Board's transmission and distribution system for the purpose of giving a supply of electricity to any premises. The Board shall offer to comply with the request unless on technical grounds it would not be reasonably practicable to do so. A private generator who wishes to make a request must provide the Board with the particulars set out in the Regulations. The Board may require further information in individual cases. Every private generator has a general duty to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that other people, are not exposed to risks to their health or safety. This obligation extends to members of the public which would include employees of any Board affected by the connection of a private installation. The connection of a private installation could produce safety hazards to a Board's employees, and provision by the private generator of information, similar to that specified in the Regulations, to the Board would help to discharge the private generator's health and safety obligations. It is thus in the interests of private generators to notify Electricity Boards that generating plant has been or is intended, to be installed, since connection of that plant to the Electricity Board's supply system could put other persons at risk. b 2.4

Connection Arranaements Each installation with private generating plant must be designed to be compatible with the Electricity Board's network to which it is to be connected. Where it is necessary for an Electricity Board to provide any electrical lines, or other electrical plant, or for any other works to be carried out to enable the installation of private generating plant, the Board may require payments in respect of any expenditure incurred in carrying out this work. The two methods of operating private generating plant considered in this document are . described below. a) Parallel Operation With The Electricity Board's System (Including Occasional Paralleling) The operation of private generating plant in parallel with the Electricity Board's system in compliance with agreed technical and commercial arrangements. Occasional paralleling allows the connection of private generating plant to the Board's system for the purpose of maintaining the continuity of supply when changing over from one source of supply to the other.

-


GIBmsh Electrical Machines Ltd. 2003

b) Operation With Alternative Connection To The Electricity Board's System

The operation of private generating plant, as an alternative to the Electricity Board': supply, arrangements being such that the generating plant cannot be paralleled with tht Board's supply system. Where it is intended to change the existing method of operation to one of the above methods then the requirements for that method must be met in full. b 2.5

System Earthina lGroundinal A S D ~ C ~ S Regulations require public supply systems to be earthed. The private generator is responsible for earthing arrangements within his installation. 2.5.1

HV System

For HV system neutral earthing, the Electricity Board may use direct, resistor reactor or arc suppression coil methods. The magnitude of the possible earth faul current will depend on which of these methods is used. The private generator's earthing arrangement must therefore be designed ir consultation with the Electricity Board such that the private system is compatible with the Board's system. The actual earthing arrangements will also be dependenl on the number of machines in use and the private generator's own system configuration and method of operation. Where Boards' systems are designed for earthing at one point only, no star poinl or earthing transformer should be connected by the private generator durin~ parallel operation. Adequate precautions must be taken to ensure that the private generator's HV system is earthed when operating in isolation from the Board's system. Where the private generator supplies an unearthed isolated part of the Board's system under controlled conditions, either through prearranged switching or the planned automatic operation of control and protection equipment, system earthing will need to be provided at the generation point. Such controlled conditions will be planned for in the design of the private generator's and the Electricity board'.^ system. All reasonable steps must be taken to avoid unearthed operation by the installation of suitable protection to detect the loss of the Board's supply. Where the Board's system is designed for multiple earthing and the generating plant is connected to this system, earthing may be achieved by the use of a busbar earthing transformer or the use of the star point of the generator. It should be noted that where it is intended to adopt a multiple earthed system, the private generator will require specific approval from the Regulatory Authorities. Care should be taken with multiple generator installations to avoid excessive circulating third harmonic currents. It may therefore be necessary to restrict the earthing to the star point of a single machine and provide automatic transfer facilities of the generator star point earth to another machine in the event of the selected machine being tripljed. The use of suitable generator transformers with delta windings may provide a means .of avoiding excessive circulating harmonic currents. The earthing arrangements must be designed such that the operation of the Board's protective system is not adversely affected. 2.5.2

LV System Electricity Boards' LV systems are directly earthed. The majority of Boards' LV systems may now be multiple earthed.

1.05.01 (A) Connection 0 1 Generating Piant.doc



I

Issue: A

I

Date: April 2003

I

Page: 7 of 14

Where a Board's earthing terminal is provided, this may be used by the private generator for earthing his installation, subject to the Board being satisfied that the existing connection is of adequate capacity. If the private generating plant is intended to operate independently of the Board's supply, the installation must include an earthing system which does not rely upon the Board's earthing terminal. Where use of the Board's earthing terminal is retained, the private generator's earthing system and the Board's earthing terminal must be connected together by means of a conductor at least equivalent in size to that required to connect the Board's earthing terminal for the installation. Where the Electricity Board's substation is on the private generator's premises and adjacent to the location of the private generating plant, the Electricity Board may allow the substation earthing system to be used in place of a separate independent earthing system. The Board's written agreement is necessary before making any connection to the Board's earthing system. Generating plant will not be allowed to operate in parallel with a Board's LV system with a star point connected to the neutral andlor earthing system unless an approval has been obtained by the Board on behalf of the private generator. Such an approval would require precautions to be taken to limit the effects of circulatory harmonics. The administrative costs incurred by the Board in obtaining such an approval may be charged to the private generator. The method of earthing will affect the means of isolation. The isolator should be selected in the following manner: a) Where the Board's LV system is multiple earthed and the Board's earthing terminal is connected to the main earthing temlinal of the installation in an approved manner, isolation of the phase conductors only is necessary. However, in the case of alternative connection, a phase and neutral isolator may be used to avoid circulating currents. b) For all other cases where a Board's earthing terminal is connected to the installation, the Board may require isolation of phase and neutral conductors for safety reasons. c) Where a Board's earthing terminal is not used or not provided (all TT Systems) phase and neutral isolation is required. Where transportable or mobile generating plant is used, it is essential that all earth connections to the generator are efficiently made prior to making off any phase connections or running the generator. b Parallel Operation With The Electricity Board's System (Includlna Occasional Parallelinal 2.6.1

I

Operational And Safety Aspects Advice on the provision of safeguards for any person intending to operate or maintain interconnected electrical systems is given in various regulatory and recommendation documents. The private generator must obtain in writing from the Electricity Board, an agreement to operate private generating equipment in parallel with the Board's system. A plant diagram and schedule giving details of ownership, operation, maintenance and control of substation plant should be prepared. The private generator must ensure that all operating personnel are competent in that they have adequate knowledge and sufficient judgement to take the correct action when dealing with an emergency. Failure to take correct action may jeopardise the private generator's or Electricity Board's system.

--

-

- -.

04 05 01 (A) Connect8on 01 Generat~ngPlant aoc

-

O Bnsh Eleclncal Machlnes Lld 2003

1

Where the point of supply provided by the Board for parallel operation is at HV, the private generator must ensure: a) That a person with authority on his staff is available at all times to receive communications from the Electricity Board's Control Engineer so that emergencies, requiring urgent action by the private generator, can be dealt with adequately. Where required by the Board, it will also be a duty of the private generator's staff to advise the Electricity Board's Control Engineer of any abnormalities that occur on the private generating plant which have caused, or might cause, disturbance to the Board's system; b) That where it is necessary for his employees to operate the Electricity Board's equipment, they have been designated in writing by the Board as an 'authorised person" for this purpose. All operations on the Board's equipment must be carried out to the specific instructions of the Electricity Board's Control Engineer. In an emergency, the 'authorised person' can open a switch without prior agreement in order to avoid danger. The operation must be reported to the Electricity Board's Control Engineer immediately afterwards. Where the point of supply provided by the Board for parallel operation is at LV, the Board, depending upon local circumstances, may require a similar communications procedure as outlined in sub-paragraph (a) above. For generation connected to an HV point of supply, the private generator and the Electricity Board may have to reach technical agreement on scheduling the real and reactive power output to the Electricity Board's system to be compatible with local system conditions. The Board may require agreement on specific written procedures to control the bringing on and taking off such generating plant. The action within these procedures will be controlled, at all times, by the Electricity Board's Control Engineer. b 2.6.2

Technical Considerations I)Fault lnfeed When it is proposed to install private generating plant, consideration must be given to the contribution which that plant will make to the fault level on the Electricity Board's system. The design and safe operation of the private generator's and the Board's installations depend upon accurate assessment of the fault contributions made by all the plant operating in parallel at the instant of fault and it is in the private generator's interest to discuss this with the Board at the earliest possible stage. 2) Synchronislng In order to operate private generating plant other than mains excited asynchronous machined in parallel with an Electricity Board's system, it is necessary to synchronise the private generating plant with -that of the Electricity Board's supply prior to making the parallel connection. The voltage fluctuation on the Board's system during synchronizing should not normally exceed 3% at the point of common coupling. Where the mode of operation of generating equipment is such that synchronizing of a machine or machines will occur at intervals of less than two hours, the voltage fluctuation should not exceed 1%. .-

I

Automatic synchronizing equipment is preferred. 3) Distortion And Interference It should be noted that the stability and electrical output of a generating plant depend upon the source of power, and may be detrimentally affected if direct coupling is made to a fluctuating source.



I

I

1 -Training Module: 04.05.01 -BRUSH

B E M Ltd.-

1z

ff


I

Issue: A

I

Date: April 2003

I

Page: 9 of 14

Where the generating plant input motive power may vary rapidly, causing corresponding changes in the output power, for example an aero-generator, the voltage fluctuations at the point of common coupling should not exceed 1%. Where the generating plant is run-up to speed as a motor connected to the Electricity Board's system, the disturbance limits must be within defined limits. Harmonic voltages and currents produced within the private generator's system must not cause excessive harmonic voltage distortion on the Board's system. The private generator's installation must be designed and operated to comply with the criteria specified limits. The level of negative phase sequence voltage at the point of common coupling on a three-phase system should not exceed 1.3% of the positive phase sequence voltage, assuming an initially symmetrical system at this point. 4) Operational Switching

Circuit-breakers and switches on the Electricity Board's system are not normally fitted with check synchronizing facilities. To avoid the risk of out of synchronism closure onto private generation and also achieve the simplest method of connecting the plant in the system, the private generator will need to arrange for his plant to be disconnected from the system in the event of a loss of the Board's supply. The Electricity Board's system may have either now or in the future. autoreclose or automatic sequence switching facilities to assist in restoring supplies after transient faults and this will affect the time settings of protection. During auto-reclose and sequence switching operations, the system could be subjected to interruptions of up to one minute; however, many auto-reciose schemes for rural systems will restore the supply in the order of one second. The conditions to be met in order to allow automatic reconnection when the Board's supply is restored are defined. Where a private generator requires his plant to continue to supply a temporarily disconnected section of the Board's system, the special arrangements necessary will need to be discussed with the Electricity Board. 5) Means Of Isolation

Every installation or network which includes a private generating plant, operating in parallel with the Board's supply, must include a means of isolation, (suitably labelled) capable of disconnecting the whole of the private generating plant infeed from the Board's network. This means of isolation must be lockable, in the open position only, by a separate padlock. The private generator must grant the Board rights of access to the means of isolation without undue delay and the Board must have the right to isolate the private generator's infeed at anyfime as network conditions dictate. The means of isolation should normally be installed close to the metering point, but may be positioned elsewhere with the Board's agreement. 2.6.3

Control Equipment Requirements Each item of generating plant and its associated control equipment must be designed for stable operation in parallel with the Electricity Board's system.

04.05.01 (A) Connection Of Generating Plantdoc


1- r

-BRUSH

B E M Ltd.-

I



1

issue: A

I

- a

Date: April 2003

I

.

...

Page:IOof14

Characteristics of the local transmission or distribution network likely to introdua special requirements for voltage or frequency control of private generating plan will be identified by the Eiectricity Board. F 2.6.4

Protective Equipment In addition to any generating plant protection installed by the private generator fo his own purposes, the Board requires protective equipment to be provided by thc private generator to achieve the following objectives: a) To inhibit connection of the generating equipment to the Board's supply unless ail phases of the Board's supply are energized and operating within thc agreed protection settings. b) To disconnect the generator from the system when a system abnormalit) occurs that results in an unacceptable deviation of the voltage or frequency a the point of suppiy. c) To disconnect the generator from the Eiectricity Board's system in the event o loss of the Board's supply to the installation. d) To ensure either the automatic disconnection of the generating plant, or where there is competent supervision of an installation, the operation of an alarm with audible and visual indication, in the event of a failure of any supplies tc the protective equipment that would inhibit its correct operation.

1 Protective Equipment For HV Supply Arrangements Suitable protection arrangements and settings for an h.v. installation wil depend upon the particular private generator's installation and the requirements of the Electricity Board's IoCal system. These individua requirements must be ascertained in discussions with the Board. The protection will have to include the detection of: a) Over Voltage b) Under Voltage c) Over Frequency d) Under Frequency e) Loss of Mains Loss of Mains protection will depend, for its operation, on the detection ol some suitable parameter, for example rate of change of current, phase angle change, or unbalanced voltages. This protection must avoid unearthed operation, and must meet the requirements for Operational Switching. Other protection could be required and may include the detection of: a) Neutral Voltage Displacement b) Over Current c) Earth Fault d) Reverse Power 2) Protective Equipment for LV Supply Arrangements

a) All Types Of Generating Plant Although additional protection will be required for some types of plant. Table Iindicates recommended protection and settings which are likely to be acceptable at the majority of sites within the UK and would meet the stated objectives. These are protection settings to disconnect equipmenl at times of system abnormalities and should not be used as control settings or operating limits. Alternative schemes and settings may be applied subject to agreemenl between the private generator and the Electricity Board.

.05.01 (A) Connection Of Generating Plant.doc

0 B N S ~Electrical Machines Ltd. 2003

-BRUSH

B E M Ltd.-

1


I 'r mwaimw - ... C

. I


I

Issue: A

I

Date: April 2003

I

Page:l2of14

Other tests must be carried out on site; tests performed before delivery and installation are not acceptable. The private generator must keep a written record of all protection settings and of tests results. A copy of this record should be available for inspection at the metering position or as required by the Board. Periodic testing of the protection is recommended at intervals to be agreed in discussion between the Electricity Board and the private generator. 2.6.7

Metering Metering equipment must be installed at the point of supply to record measurements to the requirements of the Electricity Board. These may include both the export and import of active and reactive electrical energy to and from the private generator's network. Where the metering is to be supplied and owned by the Electricity Board, the private generator must provide t h e facilities for the equipment to be installed by the Board. b

2.7

O ~ e r a t i o nWith Alternative Connection To The Electricitv Board's Svstem No parallel operation with the Electricity Board's system is allowed with this form of connection. Precautions must be taken to ensure that an inadvertent parallel connection cannot be made under any circumstances. The Electricity Board must be satisfied that the methods of changeover and interlocking meet these requirements. Earthing, protection and instrumentation for this mode of operation are the responsibility of the private generator. Where such plant is to be installed the Electricity Board must be provided with the opportunity to inspect the equipment and witness commissioning of any auto-changeover plant. The changeover devices must be of a 'fail-safe' design so that one circuit controller cannot be closed if the other circuit controller in the changeover sequence is closed, even if the auxiliary supply to any electromechanical devices has failed. Changeover methods involving transfer of removable fuses or those having no integral means of preventing parallel connection with the Electricity Board's supply are not acceptable. The equipment must not be installed in a manner which interferes with the Electricity Board's metering, cut-out, fusegear or circuitbreaker installation at the supply terminals. The direct operation of circuit-breakers or contactors must not result in the defeat of the interlocking system. For example, if a circuit-breaker can be closed mechanically regardless of the state of any electrical interlocking. then it must have mechanical interlocking in addition to electrical interlocking. Where an automatic mains fail type of generating plant is installed, a conspicuous warning notice should be displayed and securely fixed. Changeover Operated at HV. Where the changeover operates at HV the following provisions may be adopted although each has limitations: a) An electrical interlock between the closing and tripping circuits of the changeover circuitbreakers. b) A mechanical interlock between the operating mechanisms of the changeover circuitbreakers. c) An electromechanical interlock in the mechanisms and in the control circuit of the changeover circuit-breakers. d) A system of mechanical interlocks operated by transferable key system. Although any one method meets the minimum requirement, it is recommended that two methods of interlocking are used.

04.05.01 (A) Connection 01 Generating Ptant.doc

@Brush Electrical Machines Ltd. 2W3

--

- --

--

Page 130f 14 -

Changeover Operated at LV. Where the changeover operates at LV the following provisions may be adopted: a) Manual break-before-make changeover switch. b) Two separate switches or fuse switches mechanically interlocked so that it in impossible for one to be moved when the other is in the closed position. c) An automatic break-before-make changeover contactor. d) Two separate contactors which are both mechanically and electrically interlocked. e) A system of locks with a single transferable key. The general requirements for earthing and isolation should be applied. For LV generating plant connected to an installation with a Board's earthing terminal, it should be noted that a parallel path exists in the neutral earthing system. A changeover device switching the neutral as well as the phases will avoid problems associated with high frequency or harmonic circulating currents. Alternatively it will be necessary to ensure that the conductor ratings are not exceeded as a result of these circulating currents. Where the neutral is not switched, any residual current earth fault protection will have to be positioned to avoid maloperation due to the parallel neutrallearth path. b Private Generation Test Record

2.8

Ref. NO -. 1

OWNERSICOMPANYDETAILS Nameand Addmas

Telephone Number(s) 2

GENERATINGPLANTDETAILS Locanon of Generator

Type(synchronoua, asynchronous, Inverter) Mmufwturor Rated! Vdhge Frsquenol c 8 p . W IkvA) current P o m r Factor 3

ELECTRICITY BOARD SUPPLY DETAILS Voltage SONIU Dotall.

CaprcHy (kVA) Maxlmurn Fault Level Point of Common Coupllng Pmtntlon

Figure I:Private Generation Test Record

--

I4 05 01 (A) Connect~on01Generating Plant ooc

--

-O Ensh ~ l e c l n c a ~ ~ a c n ~Lta n e2W3 s

/

- 1Training Module: 04.05.01 -BRUSH

B E M Ltd.-

C


I

Issue: A

1

I

Date: April 2003

...... Page: 14 of 14

Figure 2: Protection Tests Record Ref. No.

I

On behall ol Imrbffmat the gcnmtlnp equlpmenl spec fied m Seala, 2 nar been ~Nlalled and lerledand compl~eswith lha requammenb d Eqmmnng Remrrvnsndatm G 59

I

Signed ............................................ Date ...........................................

I II

On behall o( .................................................. Elededricity Board Ihave wiblessed the tests in Secbon 4 and cerdffmat me mslalialb mnpiies with me requirements d Engineering Remmmendaton 0.59 Signed ............................................ Date .............................................

(a) These tests am to safeguardthe Eledlldty Board's sy.tm. They do not m t i i mat me whole hslallatlcn has been tested. w meeta Me requirements of the Wring Regulations, or any statutory requirements. ( b ) The o w voltage and under voltage pmtection should be teated using an extern4 variable voltage stpply. (5)

-

II

Where me freqwnc~d me plant b dependent m me mains hequamy an eamnai v m b l e frequenq audio signal generator, with sumble voltage and current WutW be used f a the under and over frequeccy proleaim tesls.

-.

-- -

04 05 01 (A) Connection 01 Generatnng Plant doc

--

0 Bnrsh Electnca~~ a c h l i e sLld 2003

B E M Lid.Training Module: 04.07.01

-BRUSH

C

ELECTRICAL DEVICE NUMBERS B FUNCTIONS

I

Issue: A

I

Date: April 2003

Page: 1 of 8

ELECTRICAL DEVICE NUMBERS & FUNCTIONS D~YIc(L NO. Device

Dslinlllon and FuncUon

46

Rcvcrse-Phase.or Phasc oalance. Current Relay

This rclay hlncl'ins when the palyphase cuncnts are 01 reversc.phasesoquence. or whm the palyphase cunonb are unbalanced or contain negative phase sequence CompmCnts above a given amount.

47

Phase Sequence Voltagc Relay

Functions on a predctormined value of polyphase vcitage in the desired phase sequence.

49

Machine or Transtomr. Thermal Relay

This relay luncbans when h e temperature of a machine armaNre. or olher bad c a v i n g winding or element d a machine, or the temperature of a power rectifier or power Eanstormer (including a power rectifier translwmer) exceeds a predeterminedvalue.

so

InmantanOverarrent, or Rate-of.Rise Relay

This rundions n s e n t a n w on an excessive value or arrres. a m a excessive r a t e d a n e n t rise. thus indicating a faun in the apparatus or drcuil being pmected.

51

AC time avereurrent Relay

Is a relay with either a dernite or inverse 6me charactenstic h a t hlncmns when me current in an ac d r a i t exoeeds a predeterminedvalue

52

AC Circuit Breaker

This is used to close and mterrupt an ac power c i r a i l under n m l condltims or lo intempt this circuit under faun a emergency m n d i l i i s .

53

Exciter ordc generalor relay This f m s me dc machina field ucita(ion l o build up during slarling or which funams W n me machine vdtage has buin up to a given value.

54

Reserved for hltufe appiIcahon

55

Power Fador Relay

4.07.01 (A) Device Numben.doc

This operates when the pawer facmr in an ac circuit rises abwe or belaw a predeterminedvalue.


-BRUSH

B E M Ltd.-


ELECTRICAL DEVICE NUMBERS 8 C FUNCTIONS I Issue: A 1 Date: April 2003

...... Page: 2 of 8

CONTENTS 1 INTRODUCTION ...................................................................................................................................... 3 2 DEVICE NUMBERS ...................................................................................................................................3

04.07.01 (A) Device Nurnbers.doc


I

INTRODUCTION Devices in switching equipment are referred to by numbers, with appropriate suffix letters when necessary, according to the function they perform. These numbers are based on a system adopted as standard for automatic switchgear by IEEE, and incorporated in American Standard C37.2-1970. This system is used in connection diagrams, in instruction books, and in specifications. b

2

DEVICE NUMBERS

of the position of these devices or of these conditions

14

Under-Speed Device

04.07.01( A ) Device Numben.doc

Functions when the speed of a machine falls below a predetermined value.

0 Bnrsh Electrical Machines Lld. 2003

-BRUSH

B E M Ltd.-


ELECTRICAL DEVICE NUMBERS & FUNCTIONS I issue: A 1 Date: April 2003

Page: 6 of 8

Device No. IDevice IDefinition and Function 49 Machine or Transformer, This relay functions when the temperature of a machine armature, or Thermal Relay other load carrying winding or element of a machine. or the I I \temperature o f a power rectifier or ~ o w e transformer r (inciudina a I I I ]power rectifier transformer) exceeds a predetermined balue. 50 J~nstantaneous l ~ h i funct~ons s instantaneously on an excessive value of current. or on Overcurrent, or Rate-of- a excessive rate of current rise, thus indicating a fault in the Rise Relay apparatus or circuit being protected. 51 AC time overcurrent is a relay with either a definite or inverse time characteristic that Relay functions when the current in an ac circuit exceeds a predetermined value. 52 AC Circuit Breaker This is used to close and interrupt an ac power circuit under normal conditions or to interrupt this circuit under fault or emergency conditions. 53 Exciter or dc generator This forces the dc machine field excitation to build up during starting relay or which functions when the machine voltage has built up to a given value. 54 Reserved for future application 55 Power Factor Reiay This operates when the power factor in an ac circuit rises above or below a predetermined value. 56 Field Application Relay Is a relay that automaticailv controls the a ~ ~ l i c a t i oofnthe field lexcitation to an ac motor some predetermined point in the slip cycle I 57 IShort Circuiting or IThis primary circuit switching device functions to short circuit or to IGrounding ~ e v i c e lground a circuit in responseto automatic or manual means. 58 IRectification Failure l~unctionsif one or more anodes of a ~ o w e rectifier r fail to fire. or to ldetect an arc-back or on failure of a diode to conduct or block' I I /Relay properly. 59 Overvoltage Relay Functions on a given value of overvoltage. 60 Voltage or Current Operates on a given difference in voltage, or current input or output of two circuits. Balance Relay 61 Reserved for future lappiication I 62 l ~ i m Delay e Stopping or IServes in conjunction with the device that initiates the shutdown, lopening Relay Istopping, or opening operation in an automatic sequence. 63 ]Pressure Switch loperates on given values or on a given rate of change of pressure. 64 IGround Protective Relayl~unctionson failure of the insulation of a machine, transformer or of other apparatus to ground, or on flashover of a dc machine to ground. Note: This function is assigned only to a relay which detects the flow of current from the frame of a machine or enclosing case or structure of a piece of apparatus to ground, or detects a ground on a normally ungrounded winding or circuit. It is not applied to a device connected in the secondary circuu or secondary neutral of current transformer. lconnected in the power circuit of a normally grounded system. I 65 ]Governor 11sthe assembly of fluid, electrical or mechanical control eaui~ment used for regulating the flow of water, steam, or other medium to the prime mover for such purposes as starting, holding .speed or load, or stopping. 66 Notching or Jogging Functions to allow only a specified number of operations of a given Device device, or equipment, or aspecified number of successive operations within a given time of each other. It also functions to energize a circuit periodicallv or for fractions of S~ecifiedtime intervals. or that is used to permit intermittent acceieratibn or jogging of a machine at low speeds for mechanical positioning. 67 AC Directional Functions on a desired value of ac overcurrent flowing in a Overcurrent Relay predetermined direction.

-

t

I

04.07.01 (A) Device Numbers.doc

~


any similar piece of apparatus

-BRUSH

B E M Ltd.-


ELECTRICAL DEVICE NUMBERS 8, FUNCTIONS I Issue: A I Date: April 2003

Device No. ]Device 90 l~egulatingdevice

I 91 92

93 94

95 96 97

l ~ o l t a g eDirectional Relay Voltage and Power Directional Relay

Field Changing Contactor Tripping or Trip-free relay

- a

..a

Page: 8 of 8

IDefinition and Function l~egulatesa quantity, or quantities, such as voltage, current, power. speed, frequency, temperature, and load, at a certain value or between certain (generally close) limits for machine, tie lines or other lapparatus. (Operates when the voltaoe across an ooen circuit breaker nr , contactor exceeds a giv& value in a given direction. Permits or causes the connection of two circuits when the voltage difference between them exceeds a given value in a predetermined direction and causes these two circuits to be disconnected from each other when the power flowing between them exceeds a -oiven value in the opposite direction. Functions to increase or decrease in one step value of field excitation on a machine. Functions to trip a circuit breaker, contactor, or equipment, or to permit immediate tripping by other devices; or to prevent immediate reclosure of a circuit interrupter, in case it should open automatically even though its closing circuit is maintained closed. Used only for specific applications on individual installations where none of the assigned numbered functions from 1 to 94 is suitable. Used for 'trip circuit supervision' monitoring tripping supplies and (sometimes) circuit continuity Used only for specific applications on individual installations where none of the assigned numbered functions from 1 to 94 is suitable. ~

1-

-BRUSH

8 E M Ltd.-

1

EQUIPMENT a SWITCHGEAR LABELLING


I

Issue: A

I

Page: 1 of 6

Date: Apr~l2003

EQUIPMENT & SWITCHGEAR LABELLING Lmer Clrcu11FuncUon

Wlre numbers

A

Cunonl bansformers tor PnmaIY proloeflon axduding ovemrrent

E

Cunent bansformersfw busbar prMoction

c

Cunent transformers farmercurrent Prntsnion (indudingcambined eanh fault waedion) and insbumants

D

Cunmt transformers lcf metering and voltage ~ n l r d

E

Relerence vdlaga f a imhlrnenls. matering and pmtsnion

F

Referem

G

Referenc~v~agefasynchronising

H

AC and AClDC supplies

1-69

Switchgear and genaratas

J

DCSupplleP

70.99

Transfamen

10.29

Redphase

30.49

Yellow Phase

50.69

Blue Phase

70.89

Residual cimhs and neunal wrrent 4xansformers

90

E B R mres ~ direcfly connecied lo earth bar

91-99 Teat windings, -ally

inoperative

ona age for voltage m t m i

K

Closing and Wp(ng m l r d cimits

L

Alarrre and indiimm W l e d by awiliiry swilches and relay antads. exduding those fa r e m e selective a n b d and tor General Indicationequipment

14.08.01(A)Switchgear Labeliing.doc

Anynumberhan t upwards

8 Brush Electrical Machines Ltd. 200:

1-1

-BRUSH

B E M Ltd.-

/


I 2 3 4 5 6

EQUIPMENT a% SWITCHGEAR LABELLING

I

Issue: A

1

Date Apr112003

Page. 2 of 6

INTRODUCTION ........................................................................................................................................ 3 GENERAL .................................................................................................................................................. 3 PREFIX LETTER...................................................................................................................................... 3 WIRE NUMBERS ....................................................................................................................................... 4 SUFFIX LETTERS ..................................................................................................................................... 4 NUMBERING TABLE ................................................................................................................................ 4

I

EQUIPMENT 8 SWITCHGEAR LABELLING Issue:

I

I

Date: April

INTRODUCTION BS3939 is the Specification for Standard Numbering of Small Wiring for Switchgear and Transformer: together with their Associated Relay and Control Panels.

2

GENERAL a) Each wire shall have a letter to denote its function, eg control of circuit breaker, current transformel for primary protection, voltage for instruments, metering and protection. The function letter shall b6 followed by a number identifying the individual wire. Every branch of any connection shali bear the same identification mark. Where it is necessary to identify branches which are commoned (e.g current transformer leads), different identification marks for the branches may be employed only i they are commoned through links, or are connected to separate terminals which are ther commended by removable connections. Suffix letters shall be used as indicated in Section 5. b) Numbering shall read from the terminals outwards on all wires. b

1

PREFIX LETTER a) Where part of a circuit is common to more than one function, the first in alphabetical order of the appropriate function letters in the table shall be used for the common part. Where the circuits split as a separate contact (eg fuse, link, switch or relay contact) the function letter shall change if necessao from the splitting point onwards. b) Circuits having functions not included in the function letter table shall not have prefix letters. FOI example, circuits of devices which provide a continuous indication, such as remote winding temperature indicators or resistance thermometers, shall not have a prefix letter unless the circuit 01 the particular indication already has a function letter. Where, however, an indication or alarm is initiated by the opening or closing of an auxiliary contact prefix 'L' or 'X should be used as appropriate. c) Where the manufacturer has been unable to ascertain from the purchaser the function letters and numbering to be assigned to equipment wiring by the time that wiring is required, the manufacture1 shali himself provide wire numbers preceded by the letter '0'. Where the appropriate function lettel only can be determined, it shall be preceded by an '0' and followed by the manufacturers owr number. The same procedure my be applied to equipment or parts of equipment not assigned tc specific contracts at the time of manufacture, subject to the purchasers approval and to the use ol ferruling in accordance with approved standard diagrams as far as these are applicable. d) Where relays are employed, the coil and the contact circuits do not necessarily bear the same function letter; this should be determined by the function of the individual circuit eg the coil circuit of a series flag relay may be 'K' but the contact circuits may bear letters such as 'X', 'L' or 'N' as appropriate. e) The following rules shall apply to current and voltage transformer function letters: i)

Current Transformers for Protection Prefix 'C'shall be used for all types of over-current protection (whether used as primary or back-up protection), standby earth fault, generator negative phase sequence, transformer winding temperature protection, and instruments fed from separate current transformer. Where duplicate primary protection is applied prefix 'A' shall be used for both, the second line being distinguished by adding 300 to the number.

ii)

Interposing and Auxiliary Transformers The function letters shall follow through any interposing and auxiliary current and voltage transformers, including such transformers when used for light current circuits, provided that these are not used as isolating transformers to couple circuits which have differing functions. When an ac supply, reflecting the primary quantities and derived from a current or voltage transformer, is rectified for the operation of instruments or relays, the dc circuit shall carry the same function letter as the ac circuit.

iii)

Current Transformer Connections for Line Drop Compensation o r Compounding Prefix 'D' shall be used for these circuits, including the current side of the isolating transformer. The connections to the voltage circuit from this transformer shall have prefix 'F'.

4.08.01 (A) Switchgear Labelling.doc

a Brush Electrical Machines Ltd. ZOO?

1

EQUIPMENT & SWITCHGEAR LABELLING

-BRUSH 6 E M Ltd.Training Module: 04.08.01

i

iv)

1

Issue: A

I

Date: April 2003

Page: 4 of 6

Voltage Transformer Connections for Automatic Voltage Control Prefix 'F' shall be used for these circuits.

Light current equipment may require numbering schemes differing from the above for complete identification. In such cases, where connections from such equipment are associated with power equipment wired in accordance with this Recommendation, the numbering of such connections shall include the appropriate prefix letter (J, W. X or Y) to distinguish them. The letter W ' is generally used for the light current side of interposing relays for control purposes. t

f)

WIRE NUMBERS

4

The wire number may consist of one or more digits as required. For functions A-G. H, J and M, the numbers shall be given in the column under Wire Numbers'. DC supplies from a positive source shall bear odd numbers and dc supplies from a negative source shall bear even numbers. Where coils or resistors are connected in series the change from odd to even shall be made at the coil or resistor lead nearest to the negative supply. SUFFIX LETTERS

5

Where similarly numbered leads from separate primary equipments are taken to a common panel (eg bus zone protection, summation metering, banked transformers, etc), suffixes A, B and C, etc, should be used to distinguish them. Where similarly numbered leads from different parts of a unit of primary equipment are taken to a common panel (eg generator and unit transformers, HV and LV sides of a transformer, etc), the leads of the subsidiary or lower voltage equipment shall be distinguished by adding 500 to the wire numbers. When more than two sets of leads require to be distinguished, specific wire numbering schemes appropriate to the case shall be issued by means of a standard diagram showing the scheme to be adopted. The method of distinguishing between sets of leads shall be shown on the individual schematic (circuit) and wiring diagrams. The distinguishing suffixes or numbers apply only in the common panel or junction box, and at each end of the interconnecting cores. When specified, however, suffixes may be omitted from the ends of the interconnecting cores. t

16

Letter lClrcuit Function A ICurrent transformers for ~ r i m a r v l~rotectionexcludina oveicurre;

1

I B C D E F G H J

.

I

NUMBERING TABLE

ICurrent transformers for busbar protection Current transformers for overcurrent protection (including combined earth fault protection) and instruments Current transformers for metering and voltage control Reference voltage for instruments, metering and protection Reference voltage for voltage control Reference voltage for synchronising AC and AClDC supplies DC Supplies

I K

]Closing &tripping control circuits

04.08.01 (A) Switchgear Labelling.doc

IWIre numbers 110-29 Red Phase 130-49 Yellow phase 50-69 Blue Phase 70-89 Residual circuits 8 neutral current transformers 90 Earth wires directly connected to earth bar 191-99 Test windings, normally inoperative

I

1-69 Switchgear & Generators 70-99 Transformers 1-69 Switchgear & Generators 170-99 Transformers l ~ n number y from Iupwards


I

1

8 SWITCHGEAR LABELLING --

Issue: A

.-

BLANK PAGE

.08.01 (A) Switchgear Labelling.doc


C HlGH VOLTAGE PHASING CHECKS -BRUSH

B E M Ltd.-


I

Issue A

I

Date Apr112003

Page 1 of 6

HlGH VOLTAGE PHASING CHECKS

04.09.01 (A) HV Phasing.doc


CONTENTS 1 INTRODUCTION ........................................................................................................................................ 3 2 PHASING OUT OF HV SYSTEMS .......................................................................................................... 3 3 PHASING STICKS ..................................................................................................................................... 5

04.09.01 (A) HV Phasingdoc

O Brush Electrical Machines Lld. 2003

HIGH VOLTAGE PHASING CHECKS -BRUSH

B E M Ltd.-

Training Module: 04.09.01 I

I

Issue: A

I

Date: April 2003

Page: 3 of 6

INTRODUCTION The fundamentals of phasing out of high voltage (HV) power systems are detailed hereafter.

A

WARNING: Specialised HV training is required before entering any HV switchgear panels.

When synchronising a generator to a busbar system it is imperative to check that the Voltage Transformers (VT's) to the synchronising gear reflect correctly the phase rotation and phase difference between the two systems. Some switchgear breakers have no VT's fitted, these are normally ring main units or auxiliary switchgear. In these situations the only way of checking these is Phasing Sticks (See Section 3). Phase displacements between the output lines of a three phase ac generator are 120 electrical degrees apart. This is to assure power is taken equally during the rotation of the prime mover. These lines can be referred as Red, Yellow, Blue phases, or L l , L2, L3, or R, S, T or U. V, W dependant on which international standard is used. It is important to ensure the order in which the line voltages rise. This defines the phase rotation of the system. With an ac generator the phase rotation is set by the direction of rotation of the prime mover. Nowadays phase rotation is U, V. W irrespective of mechanical rotation for an ac generator. During phasing checks we cannot rely on HV cable core identifications, as any joints in the cable would be carried out to suit the lay of the connectors and not the continuity of the core numbers by the cable jointer, Likewise with the secondary of the VT's the cabling may pass through several interconnecting termina blocks before arriving to the synchronising instrumentation. b 2

PHASING OUT OF HV SYSTEMS Before joining two systems the following criteria must be met: 1) Voltages on both systems must be equal. 2) The frequency of both systems should be identical. 3) The phase difference between supplies should be zero. 4) The phase rotation of both supplies should be the same. 5) Vector windings should be identical (Transformer in circuit only). to 3) are unobtainable due to fluctuating site load so there are acceptabie limits that wil In practice I) allow the two systems to be joined. Any voltage mismatch will cause reactive currents to flow between the interconnected systems and with any phase difference this creates a mechanical shock to the generatol rotor system and therefore the stator assembly. This should be minimised. Any phase displacemen1 between the two systems caused by slip between a generator and a busbar frequency will cause the generator to electrically lock into synchronism the instant the generator breaker is closed. It is norma practice to synchronise with the Prime Mover slightly above synchronous speed, this assures that powel is taken up by the set the instant the breaker is closed. This prevents the set tripping out on revers€ power. b

.

X

Bus coupler

-

qVr1 X

Generator breaker

Vr2

Figure I: Typical Generator To B e Synchronised 04.09.01 (A) HV Phasing.doc


Figure 1 shows a typical situation where a generator is to be synchronised to a network. Where possible the following procedure should be performed to ensure that the following criteria are met: > Phase rotation of the set is correct. > The VTs are correctly reflecting the status of the HV system. > External wiring to controllsynchronising panel is correct. > The correct phasing of the incoming machine is correct, ie Red phase to Red phase etc.

A

WARNING: The use of Low Voltage Phase rotation meters on an unexcited HV set i s dangerous practice and should not be performed.

i

The following is a typical exercise to synchronise a machine as shown in Figure 1: 1) lsolate bus coupler and Generator breaker as per current safety rules. lsolate any synchronising breaker signals ensuring that none of the breaker close signal cabling can 'short down' to earthed metalwork. 2) Confirm that three phase VTs are used. Check the earthing of the VI Winding (eg yellow earthed or neutral earthed). Providing VT earthing is identical the following procedure may be followed. 3) Earth bus section as per current safety rules. 4) lsolate and insulate the three machine output cables. If not insulated, remove the generator neutral 'stat connections. Note: lsolate at the machine temlinals should it be suspected that due to the age of the machine the ends of the windings been swapped due to stator leakage currents. However not all machines were graded for line voltage to the star point. 5) Remove bus section earthing and return to normal operation with generator leads still isolated and insulated as per current safety rules. 6) Close bus coupler and energise up the RHS busbar. 7) Close Generator breaker. (This is referred to as back-energising the generator). 8) Check and record phase rotation of VT1 (generator). 9) Check and record phase rotation of VT2 (busbar). b 10) Produce phasing chart as shown in Table 1. Verify the phasing by measuring the .VT secondary ac voltages. Verify (ifconnected) that the synchroscope is reading twelve o'clock and that the check synchroniser unit contacts are closed (iffitted). Table 1: Phasing Chart Yellow Yellow Blue

110V 11OV

Zero IlOV

llOV Zero

At this stage the phasing of the VT's across the breaker have been prove using the busbar supply. The phase rotation of the running supply has been verified. 11) lsolate bus coupler and generator breaker as per current safety rules. 12) Earth bus section as per current safety rules. 13) Reinstall generator HV cabling. 14) Remove bus section earthing and return to normal operation. 15) Ensure bus coupler is open and locked off 16) Start generator and deadbar. Close generator breaker onto RHS busbar. 17) Check and record phase rotation of VT1 and 2. Ensure that this is the same as in steps 8) and 9) (this proves that the phase rotation of both machine and busbars are the same). 18) Produce phasing chart as shown in Table 1. Verify the phasing by measuring the VT secondary ac voltages. Verify (if connected) that the synchroscope is reading twelve o'clock. At this stage the phasing of the VT's across the breaker have been proven, using the busbar supply. The phase rotation of both the running (busbars) and incoming (generator) supplies are correct. b

:.09.01 (A) HV Phasing.doc

O Brush ElecUical Machines Lld. 2003

1-

HIGH VOLTAGE PHASING CHECKS

-BRUSH

B E M Ltd.-


I

Issue: A

I

l* b $ m 5- m m - a

Date: April 2003

. a *

Page: 5 of 6

PHASING STICKS The final check is to verify the HV cabling, this is done using a combination of live line tester with phasing sticks. Refer to the manufacturer's instructions before using this equipment.

Flgure 2: Phasing Stick Connectionsb Figure 2 outlines the connection for the equipment. Firstly, using the live line tester only, verify the voltages A l . 81, C1, A2, 82. C2, individually to earth and record in a chart similar to Table 2. Table 2: Voltage Verification Chart

Phase to neutral volts = Line Volts d3

" Volts on phasing sticks when in synchronism = 2 x

Line Volts 43

Connect up the phasing sticks and now verify the remaining readings between incoming and running phases. Ensure that the reference synchroscope is reading 12 o'clock by trimming the incoming machines governor. When all readings are acceptable synchronising is permissible. b

04.09.01 (A) HV Phasing.doc

D B ~ s Electrical h Machines Ltd. 2003

-. . ...

HIGH VOLTAGE PHASING CHECKS -BRUSH

B E M Ltd.-


I

Issue: A

I

Date: April 2003

Page: 6 of 6

BLANK PAGE

-04 09 01 (A) HV Phaslng doc

--

D Brush Electrical h 4 a c h l G ~ t a2003

ELECTRICAL POWER

-Power Flow

GENERATOR

R!

Line Voltages

/

LOAD

"R Y

-

'Y

-

'9

"B R

I

~ $ 0

I Neutral Current (4)

, VY

04.10.01 (A) Electrical Power.doc


ELECTRICAL POWER -BRUSH

B E M Ltd.-


1

lssue A

1

- a

Date Apr112003

-

..

Page 2 of 16

CONTENTS 1 RESISTANCE, INDUCTANCE 8 CAPACITANCE ................................................................................... : 1.I Resistan .............................................. 1.2 lnductan 1.3 Capacitance 2 CURRENT8 3 ACTIVE POWER ........................................................................................................................................ t I REACTIVE POWER ................................................................................................................................. 1( 5 POWER FACTOR 8 APPARENT POWER ............................................................................................. 1( j THREE PHASE POWER ......................................................................................................................... 1f I TARIFFS AND POWER FACTOR CORRECTION If

.................................................................................


0 B ~ s Electrical h Machines Ltd. 200:

[SmEiilI -BRUSH

B E M Ltd.-


I

Issue: A

I

Date: April 2003

RESISTANCE, INDUCTANCE & CAPACITANCE 1.1

Ii

-

#

ELECTRICAL POWER

.. . ...

Page: 3 of 16

Resistance Ohm's Law establishes that the relationship between voltage and current in a simple dc circuit is constant i.e. V// = Constant. During Ohm's experiments he found that this constant varied from sample to sample. The ratio V/R is called 'resistance' or R, which in electrical terms can be considered as opposition to flow of electrons. in a mechanical analogy, electrical resistance is like friction. Resistance is present in all ac electrical circuits. The amount of resistance is usually relatively small, but can be high in devices such as heaters etc. and are referred to as 'resistive' loads. F

1.2

Inductance Wherever a magnetic field is produced by an electric current passing through a circuit, that circuit displays the phenomenon of 'inductance'. A mechanical analogy would be a large grindstone with a turning handle. Because it is old its bearings are stiff and rusty, giving a lot of friction. When we try to turn the handle, we must overcome this friction, causing heat and loss of energy at the bearings and making ourselves hot with the effort expended.

Figure I : Grindstone Analogy Since the grindstone is heavy, in addition to friction we also need to overcome its inertia in order to provide the wheel with an accelerating force for it to gather speed. The greater the weight or inertia, the greater the force needed to accelerate. An electric circuit exhibits the same effects. It has resistance (friction in the mechanical analogy), and, in order for a current to flow, a pressure in the form of a voltage is needed to overcome it (our efforts in the mechanical analogy). An electrical circuit has inertia too. It opposes any attempt to speed up the current or to cause it to grow. This inertia in an electrical circuit is called 'inductance' and is due to the fact that any electric current causes magnetisation. This effect is greatly increased by the presence of iron for example (which magnetises easily). F

04.10.01 (A) Electrical Powerdoc

O Brush Electrical Machines Lld. 2W3

Figure 2: Electromagnetic Induction Faraday's Law of Electromagnetic lnduction states that, if a conductor moves in a magnetic field, an emf (or electro-magnetic force or voltage) is induced in it. The opposite is also true i.e. an electric current in a wire gives rise to a magnetic field along its axis (Oersted's Principle). To explain how inductance arises in a circuit due to its magnetisation, which causes it to display electrical inertia or 'sluggishness', can be explained by the following example. Consider a coil of wire through which a current is flowing, there is a magnetic field Concentrated along its axis. If the current increases, then the magnetic field also increases which, by Faraday's Law induces creates an emf (voltage) in each tum. The direction of the emf would be such as to oppose the change i.e. in this case to try to prevent the current increasing, and is therefore often referred to as the 'back-emf. Circuits incorporating equipment that have coils, especially those with iron such as generators, motors and transformers, have both resistance and inductance. They are generally referred to as 'inductive' loads. b

1.3

Capacitance Capacitance in electrical terms is the ability to store energy. This should not be confused with the word 'capacity'. Care is needed to distinguish between 'capacitance' and, 'capacitor' which is a device for storing energy. A mechanical analogy of an electric capacitor would be a large, closed tank filled with water, fitted with a flexible membrane down the middle, and fitted a pressurised water supply on one side and a suction outlet on the other side.

Figure 3: Water Tank Analogy 1.10.01 (A) Electricaf Power.doc


n g Module: 04.10.01

I

Issue: A

I

Date: April 2003

I

Page: 5 of 16

Initially, with the valve closed both sides of membrane are at equal pressure and the membrane is undistorted. When the valve is opened water under pressure flows into the right hand side of the tank and out through the left side. Water movement through the tank itself compared to the flow through the pipes is small compared to the large cross-section of the tank, hence the membrane will distort right to left as illustrated in Figure 3. Eventually when the distortion is such as to produce a pressure equal to the incoming water, water flow will cease, and the membrane will be in a state of elastic strain. Closing the valve at this point, the right hand side of the tank is under pressure with static energy stored in the stretched elastic membrane. Although water can move through the external piping, there is no transfer of water within the tank across the membrane.

I

In an electric capacitor, the current entering one side and leaving the other side is the 'charging current', which is like the water flow in the pipes in the water tank analogy. In the water tank, reversing the process would cause the stretched membrane to relax or release the static energy. Similarly passing a current into a capacitor 'discharges' it and recovers the stored energy or capacitance. Examples of 'capacitive' loads are obviously capacitors, overheads lines and some long, straight cable runs. b

2

CURRENT 8 VOLTAGE For a simple dc circuit that is purely resistive, Ohm's Law states that V/l = R (VoltagelCurrent = Resistance), i.e. the relationship between voltage and current is constant. In an ac circuit this constant relationship is illustrated in Figure 4.

Figure 4: Resistive Load Waveforms When the circuit is switched on, the voltage and current waveforms coincide and are said to be 'in phase'. In an inductive dc circuit however the current rises-slowly at first since the applied voltage is overcoming the 'back-emf, or inertia of the system to make the currentgrow. This characteristic has a significant effect on the voltagecurrent waveform relationship in a purely inductive ac circuit. b

ELECTRICAL POWER

I

I

Figure 5: Inductive Load Waveforms In Figure 5 the switch in a purely inductive ac circuit is closed when the voltage wave is at the positive peak. Because the load is inductive, the first application of voltage will cause the current to rise slowly. and it will continue to rise in this manner until 'A', by which time the voltage wave has fallen to zero. At this point there is no more voltage drive and the current ceases to rise i.e. maximum positive 'P'. After this point the voltage becomes increasingly negative, opposing the current flow and causing the current to reduce. During the times 'B' and 'C' the voltage is negative, so the current becomes increasingly negative. After 'C' the voltage passes through zero, and with no voltage drive the current ceases to decrease i.e. maximum negative 'Q'. During time 'Dmthe voltage becomes positive again, opposing the current's negative flow. The current becomes less negative and returns to zero at 'D' when the voltage is at its positive maximum. The condition at 'D' is the same as the start time '0' and the whole cycle begins again. It can be seen from Figure 5 that the current wave is 'late' compared to the voltage wave by one quarter of a cycle. It is said to 'lag'. If one cycle is 360°, the current waveform lags the voltage waveform by 9 0'. In a capacitive dc circuit a charging current is set up as the voltage is applied, and the growing charge on the capacitor increasingly opposes the applied voltage until the charging current has decayed and ceased. The effect of this characteristic in a capacitive ac circuit on the voltage-current waveform relationship is illustrated as follows. F



I

~RUSHJ -BRUSH

B E M Ltd.-

ELECTRICAL POWER

(a) SQUARE.WAVE CURRENT

(b) SINUSOIDALCURRENT

Figure 6: Capacitive Load Waveforms in Figure 6(a) the ac charging current is considered to be square shaped instead of the classical sinewave shape. Between 'A' to 'B' the charging current is constant and positive and the capacitor is charging at a constant rate. At the same time its charge voltage E, , which is opposing the applied voltage V, is decreasing negatively to its negative maximum at 'P'. At this point the applied voltage V is at its maximum positive. Between 'B' and 'D' the charging current has reversed and is constant and negative and the capacitor is discharging at a constant rate. At the same time its charge voltage E, , which is opposing the applied voltage V, is increasing positively to its positive maximum at 'Q'. At this point the applied voltage V is at its maximum negative. At 'C'the capacitor has no charge. From 'D' to 'E' the charging current is once again constant and positive, and its charge voltage E, is decreasing negatively towards its negative maximum, passing through zero at 'E'. Beyond this point the conditions are the same as the start and the whole cycle begins again. For the purpose of explanation a square shaped charging current was assumed. This would not the case in practice where the charging current wave would normally be a sine-wave. In Figure 6(a) the square topped and angled lines are 'rounded off implying a gradual rather than a sudden change, which approaches the sine-wave shapes shown in Figure 6(b). From Figure 6(b) it will be noted that the current Iis ahead in time of the applied voltage V , and the current is said to 'lead' the applied voltage. If one cycle is 360°,the current waveform leads the voltage waveform by 90".b

ELECTRICAL POWER

Figure 7: Inductive 8 Capacitive Currents Figure 7 illustrates on the same diagram how inductive circuit currents lag the applied voltage by 90' and how capacitive circuit currents lead by 9 0'. It will be noted that since each current is displaced 90"either side of the voltage wave, there is 180' between them, or in other words inductive and capacitive current waves are exactly opposite to each other in phase. Convention considers that capacitive loads 'supply' current , whilst inductive 'take' current, which is important to remember since most practical circuits are a combination of capacitive. inductive and resistive loads. b 3

ACTIVE POWER The purpose of most electrical systems is to generate electrical power and to convey it to those consumer installations which will use it. When an electric generator is delivering this energy, or the rate of delivering 'real' power, it is at the same time usually delivering another type of 'false' energy which may also be required by certain consumer equipment. To distinguish between them, 'real' power, which represents real energy, is called 'active power' (sometimes also called 'wattful', 'actual', 'true'. 'real' or 'working' power). The other kind, which is the rate of delivering 'false' energy, is termed 'reactive power' (sometimes also called 'wattless' or 'blind' power). 'Reactive' power is dealt with separately in Section 4. 'Active' power may be used to energise a mechanical drive, or to provide heating and lighting, or to energise control and communication systems such as instrumentation or radio and telephone installations. All of these things consume energy, and that energy is absorbed at a stated rate i.e. power consumption. 'Real' power consumption is measured in 'watt' (W), kilowatt (kW) one thousand watts, or megawatt (MW) - one million watts.

-

Electric power is usually obtained from a generator, which receives its power from a prime mover (engine petrol, diesel or gas; turbine gas, steam, water or wind). With the exception of water and wind driven sets, the energy delivered by the prime mover to the generator is derived from the fuel which they bum i.e. the energy source is ultimately a chemical one.

-

-

Voltage is a pressure, and current is a flow. In mechanical engineering, power -the rate of doing work is the product of pressure and volume Row. In electrical circuits, power is the product of voltage and current i.e. Power = V x I.If V is measured in volts and Iin'amps, their product is the power in Watts (

w.

In dc this presents no problem. Both V and Iare steady quantities and their product is a direct measure of the power in watts. With ac however the same rule applies, but these quantities are constantly changing as the voltage and current alternate. It is therefore necessary to look at this product instant by instant to see if it has an average value. b

04.10 01 (A) Electrical Power.doc

-

-

.-

--

-

8 Brush Eleclncal Machlnes Lld 2003

li-C


B E M Ltd.-


I

Issue A

I

Date Apr112003

..

.

...

Page 9 of 16

-

Figure 8: AC Power Resistive Load Consider an ac voltage feeding a purely resistive load. If the top wave of Figure 8 represents the voltage, the second wave represents the current is in phase with the voltage. The power at any instant is the product of the voltage and current at that instant. At b, b and t8 both waves are at zero, so their product is also zero. At any time in the first half-cycle voltage and current are both positive, so their product is also positive, and is greatest at time t2, where both are at their maximum. At any time in the second half-cycle voltage and current are both negative, so their product is again positive and is greatest at b, where both are at their negative peaks. The power wave is therefore the bottom waveform in Figure 8. It is of double frequency i.e. two peaks for every one voltage peak) and is wholly above the line (positive). It represents pulses of power, always positive, and the average value of that power is midway between the power peaks and troughs. In this case, for a purely resistive load the average, or mean (peak to peak) power P = V x I(watts) and is the 'active' or 'true' power, and is the same as i n a similar dc circuit. .

-

'Active' power is measured by a wattmeter, which automatically calculates the value of 'real' power in the ac (or dc) circuit. b




B E M Ltd.-

I


I

Issue A

I

Date Apr112003

Page. 10 of 16

I

REACTIVE POWER

0

M a n Vdu.

= Zerowarn

I

-

I

Figure 9: AC Power Pure Inductive Load Figure 9 shows waveforms for a purely inductive ioad, in which the current 'lags' the voltage by 90". Using the same principles as before to determine the instantaneous values of the product of current and voltage, results in the 'active power' waveform shown at the bottom of Figure 9. Because of the 'phaseshift between current and voltage, the average, or mean (peak to peak) value of 'active power' is zero.

I

Similarly, for a purely capacitive load, in which the current 'leads' the voltage by 90°,'the average, or mean (peak to peak) value of 'active power' will also be zero. If there is nett power in a purely resistive ac ioad only, there is a need to reconsider the rules for determining power for the more usual ac loads that include inductive, capacitive and resistive elements, since simple multiplication of current and voltage values do not represent the 'true' power in watts. b In circuits incorporating inductive andlor capacitive elements i.e. non-pure systems, the product of voltage and current is known as 'Reactive' or 'Wattless' or 'False' or 'Blind' power is measured in VAr (volt-amp reactive), and is a measure of the energy stored (but not consumed) in a magnetised system.

I

I1

In installations that incorporate transformers and motors, which all need to be magnetised, the demand for VAr's can be considerable 'Reactive' power is measured by a varmeter, which automatically calculates the value of 'reactive' .power in an ac circuit. b 5

POWER FACTOR 8 APPARENT POWER Only power in purely resistive and purely reactive (inductive and capacitive) circuits has been considered so far. Figure 10 shows the general case for a more typical circuit incorporating both resistive and inductive elements.

04 10 01 (A) Electrical Power doc

--

@ Bnsh Electrical Machlnes LtO 2003

I


B E M Lid.-


I

Issue: A

/

Date: April 2003

I

Page:lloflG

-

Figure 10: AC Power General Case The resistive part of the load draws in-phase current, and the reactive part a current lagging 90°, Between them they draw a single current somewhere between in-phase (0' lag) and 90' lag, as showrI on the second curve. The actual phase angle between current and voltage is usually written cp (Greek 'phi' for 'phase'). If the same process is used, as before, of multiplying the voltage by the current at each instant of time the power wave produced (bottom of the figure) would again be double-frequency but will now be partl)I asymmetrical, and its average value will be positive and will lie somewhere above the zero line. This means that, in the general case, the average active power (watts) will always be less than the maximumI value which occurs in the purely resistive case, where the nett power is V x Iwatts. Because in the early days of electricity power was always the simple product of V and I,which is correclt for dc circuits, a correcting factor was introduced for power in ac circuits. This correcting factor was given the name 'power factor' ('PF') and is the cosine (cos) of 'phase difference' angle between the! current and voltage. Thus for an ac circuit nett power is V x Ix coscp. For ac circuits incorporating capacitive elements, where the current 'leads' the voltage i.e. opposite 01 'negative' compared to inductive loads, the nett power formula above is still valid since for a particulal angle, the cosine for a positive or negative angle is the same. b


0 Brush Electrical Machines Ltd. 2M): I-


B E M Ltd.-


I

Issue: A

I

Dat

Figure 13: Power Vectors (Two Generators) If one generator is being operated in parallel with the National Grid then the whole National Grid load still sets the power factor, but any individual generator can be operated at any power factor because it so relatively small. It is only the total system Watts and VAr's that is fixed. It can be seen from Figure 13 that it is permissible to add and subtract Watts, and to add and subtract VAr's. Adding and subtracting VA's however produce a non-meaningful result. b

Figure 14: Power Factor Meter Power factor meters as shown in Figure 14, are calibrated to read cos cp and always show a positive number but are arranged to indicate lagging or leading power factors. b It is often convenient for operators to consider 'active' and 'reactive' power separately, though in practice both are present together, travel down the same cables and wires, and are produced by the same generator.

. ... .-- - - -Q10 01 (A) Electrical Power ooc

.

..

. .

.-

-

0 Bnsh Electnwl Mach nes Ltd 2W3

ELECTRICAL POWER

1

m-

A

Field

Figure 15: Active & Reactive Motor Power Figure 15 shows how active and reactive power to a motor is generated, distributed and consumed. Active or 'true' power originates from the generator's prime mover as mechanical output from the turbine. On the other hand reactive power emanates from the generator's excitation system through its main field. Both powers come from the generator itself through a common cable. At the switchboard they give a common current indication on the generator ammeter, and both combine to give a'common power factor indication. They separate to give independent wattmeter and varmeter indications. They recombine to feed the motor through a common cable. At the motor the reactive power is used to magnetise the machine, and the active power supplies the (variable) mechanical load and also the losses. F



L

ELECTRICAL POWER

I

6

4-

THREE PHASE POWER Consider a three phase system incorporating a star-connected three phase generator connected to a three phase star connected load as shown in Figure 16. The load is 'balanced' consequently the neutral current is zero. Power Flow

I

Line Voltages

&

GENERATOR

LOAD

IR

-

VR Y

--

VBR

lY

B!

*

vYIB

-

Neutral Current (=O)

, VY

Figure 16: Three Phase System Each of the three phases are considered separately, with each generator winding having a phase voltage e.g. VR, developed in it. Because the load is balanced, the line current in eqch phase is the same e.g. I, = IRan so on. The active power transmitted in each phase is: VR X IL X COS (p thus the total for all three phases is: ~xVRX/LXCOS(~

.

The line-to-line voltage VL is 43 x Phase voltage, e.g. d3 x VR, thus the total power three phase active power is: P = ~ X V ~ X I ~ X C O Swatts (~ The above formula is correct for whether the source or load is star or delta connected. b

7

TARIFFS AND POWER FACTOR CORRECTION Installations where some or all of the electrical power is imported will be subject to a charge or tariff for the provision of this power by the supply Authority or Utility. This tariff will in general be in two parts one based solely on the energy consumed to meet the suppliers fuel and other running costs, the second part of the tariff is required to meet each consumer's'contribution to the suppliers capital Costs which relate to the provision and ongoing repairireplacement of generating and distribution plant.

-

To meet suppliers fuel and running costs, the consumer is provided with a meter which records the total energy consumed in k w h (kilowatt-hours) or MWh (megawatt-hours) and is charged at the appropriate rate per 'unit' (kwh or MWh). This is usually the only charge for domestic installations, which are essentially resistive loads.



I I

To meet the suppliers capital costs, which is a reflection of the generation capacity that needs to be installed, the tariff is based on a comparison of the consumers expected maximum load (stated by the consumer prior to commencement of the supply contract) and the actual maximum load in kVA i.e. 'Maximum Demand kVA'. In practice maximum demand is not measured at any given instant, but is averaged over successive periods of (usually) 30 minutes. To limit this part of the payment it is in the consumers interest to limit the magnitude of kVA demand to the stated expected maximum load, or below. To achieve this it is good practice to operate plant as efficiently as possible, which in electrical terms means operating equipment at the best power factor to produce the lowest kVA demand as explained below. b

Figure 17: Power Factor Correction Figure 17 shows a typical power vector diagram for an inductive load e.g. an induction motor. It will be noted that for a given power rating W, the VAr reduces from VAr, to VAr2 as the power factor improves from cpl to cp2, and there is a resultant reduction in the VA value (VA2 compared to VA,). When W and VA are equal the VAr value is zero and the power factor angle cp is 1.0 or Unity. Power factor improvement is often achieved by the introduction of special power correction equipment into the system, which incorporates capacitors which have a leading VAr characteristic. Usually systems are operated slightly under-corrected i.e. the power factor is less than unity, since the extra maximum demand amount remaining is small compared to the cost of extra capacitance required to achieve full correction. It will be noted that it is also possible to over-correct the power factor such that a leading reactive power (VAr) element is present, but this is not usual since the reactive power element will increase the value of the apparent power or maximum demand VA. Generally, where practical and safe, electrical equipment should be operated at full load since most equipment is designed to operate at it's most efficient at full load. Operating at part load can be inefficient and may result in a poor power factor that may have an impact on the overall plant maximum demand kVA. b


@ Brush Electrical Machines Ltd. 2 W 3

MODULAR AUTOMATIC VOLTAGE REGULATOR (MAVR) PRINCIPLES

15.01.01 (A) MAVR Principles.doc

0 Brush Electrical Machines Ltd. 2Wi

-BRUSH

[h- ......

B E M Lid.-


MODULAR AUTOMATIC VOLTAGE e REGULATOR (MAVR) PRINCIPLES 1 Issue: A ( Date: September 2002

I

Page: 2 of 12

CONTENTS 1 THE BRUSHLESS GENERATOR .............................................................................................................3 2 GENERATOR OPERATION ...................................................................................................................... 5 General............ ............................................................................................................................ 5 2.1 ..................... ................................ 5 2.2 Island Operation ....... 2.3 Parallel Operation................................................................................................................................ 6 7 3 PRINCIPLES OF AUTOMATIC VOLTAGE CONTROL 4 PARALLEL OPERATION 8 . . ......................8 Quadrature Current Compensation.................................................................... . 4.1 10 Machines In Parallel ........................ ............................................................................................. 4.2 4.3 Governor Droop................................................................................................................................. 11 12 5 THE GENERATOR CAPABILITY DIAGRAM

. . .

............................................................................ ..........................................................................................................................

. .

.........................................................................................



ICI V U L I A U C

AAVR) 05.01.01

I

I

Issue: A

I

is

15-

I


., .

I

..,

Page: 3 of 12

THE BRUSHLESS GENERATOR

Figure 1: DAX Type Generator The above diagram shows a typical single end drive Brush DAX type generator. Important points tc note are: The purpose of the pilot exciter is to provide a source of excitation power whenever the machine is running. The pilot exciter is a single phase permanent magnet generator (PMG), with the magnet: mounted on the shaft, and the AC output being generated in the stator. Typically, on a 300013600 rpn machine. the PMG produces between 200 to 300 volts at 4001480Hz. The main exciter is of the brushless type and comprises a fixed pati called the main exciter stator and a rotating part called the main exciter armature. The main exciter stator is comprises iaminatec steel field poles around which are the field colls. Leads are taken from the field coils to a terminal bo) on the side of the housing. The three phase AC output from the main exciter armature is connected to the rotating rectifiel assembly, which converts the AC output to the DC input required in the generator rotor winding. Thc rotating rectifier assembly is a three phase full wave bridge configuration, with fuses in series with eact rectifier diode. On larger machines more than one fuselrectifier diode may be fitted to each arm of thc bridge. Electrical connections between the rectified output and the generator rotor winding are carried i r .the central bore through the machine shaft. The power output of the machine is produced in the generator stator windings The following diagrams illustrate how the various elements are connected in a brushless generator AVF system. b

)5.01.01 (A) MAVR Principles.doc

B B ~ s Electrical h Machines Ltd. 200:

-BRUSH

MODULAR AUTOMATIC VOLTAGE @ REGULATOR (MAvR) PRINCIPLES Issue A Date September 2002

li-

B E M Ltd.-

I


...... Page 4 of 12

PMG EXCITER

I

n

PRIME MOVER

n ROTATING RECTIFIER

ROTOR STATOR

--

f

SENSING VT CT

r

,

AVR

i'i'i' LOAD

Figure 2: GeneratorlAVR Block Diagram b Rot~4.-'-'-'-'-'-'-'-'-'-----------.

1

......................

I

RxMe Heat Sink

I

Negative Heat Sink : ........................

I_-.-_-_-__._.-.-.-.-.-.-.-.-.-.-.

I I

Figure 3: Brushless Generator Schematic b



-BRUSH

lI43Immlm -. .

B E M Ltd.-


1

MODULAR AUTOMATIC VOLTAGE # REGULATOR (MAVR) PRINCIPLES I Issue: A I Date: September 2002

.a*

I

Page: 5 of 12

GENERATOR OPERATION 2.1

General The power (MW, kW, W or Watts) supplied at the generator terminals is provided by the fuel supplied to the prime mover (turbine or engine), which is determined by the prime mover governor.

I1

When a generator is used to supply power, it can be operated isolated, sometimes referred to as island mode, or in parallel with a system or other machines. 2.2

Island Oueration In island operation, the machine speed is determined by the load and fuel supply, and the generator voltage is determined by the excitation. Because the unit operates in isolation, the generator power factor is equal to the load power factor.

- FLEL

FLEL REOULATOR

MECHANICAL

ELECTRICAL WWER

FcVEQ

\

PRlME

*/

MOMR

LOAD

GENERATOR

A FlEm

GOMRMXl

C

SPEED S I N

C

VOLTAGE

VOLTffiE S I W

Figure 4: Island Mode Operation When operating in isolation, an increase in load will have two effects: 1) Speed will initially fall because the energy being supplied by the fuel is less than that required by the load. The speed reduction is detected by the governor, which opens the prime mover fuel valve by the required amount to maintain the required speed.

2) Voltage will initially fall because the generator excitation is too low to maintain nominal voltage at the increased load. The voltage reduction is detected by the automatic voltage regulator (AVR) which increases the excitation by an amount required to maintain output voltage. F

I

-BRUSH

B E M Ltd.-


FUEL

FUEL REGULATOR

A

1

MODULAR AUTOMATIC VOLTAGE # REGULATOR (MAVR) PRINCIPLES Issue: A 1 Date: September 2002

-

MCHANlCAL FiXER PMME MOVER

I

I

Page: 6 of 12

ELECTMCAL POYKR

.J \

- . ...

V

GENERATOR

LARGE POWER SYSTEM

FIELD

SWSlNG

%PEED S1-

vaTm

1

SIWS

REGULATDR

I

Figure 5: Parallel Operation When a machine operates in parallel with a power system, the voltage and frequency will be fixed mainly by the system. The fuel supply to the prime mover determines the power which is supplied by the generator and this is controlled by the governor. The generator excitation determines the internal emf of the machine and therefore affects the power factor when the terminal voltage is fixed by the power system. The governor and AVR are arranged to have characteristics which allow them to be stable when the generator is operating in parallel with a power system. (See Section 4 - Parallel Operation). In single and parallel operation it is important to realise that power is determined by the fuel supply to the prime mover, and that excitation determines voltage when single running, and power factor when parallel running. b

05.01.01 (A) MAVR Pn'nciples.doc

0 B N S ~Electrical Machines Ltd 2002

-BRUSH

B E M Ltd.-


L

1

MODULAR AUTOMATIC VOLTAGE @ REGULATOR (MAVR) PRINCIPLES 1 Issue: A I Date: September 2002

I

.. .

..a

Page: 7 of 12

PRINCIPLES OF AUTOMATIC VOLTAGE CONTROL PILOT EXCITER

BRUSHLESS GENERATOR

VOLTAGE

8 CURRENT SENSING TRANSFORMERS

--

,T

/

, CONmOUEo wcnnm mJUsTPBLE SlGNAL

REFERENCE VOLTAGE

AMPLIFIER

STABlLlSlNG

NEw.cm

Figure 6: Principal Components Of A Generator And MAVR The above diagram shows the principal components of the generator and its AVR.

.

The voltage transformer (VT) provides a signal proportional to line voltage to the AVR where it is compared to a stable reference voltage. The difference (error) signal is amplified and then used to control the output of a thyristor rectifier which supplies a portion of the PMG output to the exciter field. If the load on the generator suddenly increases the reduction in output voltage produces an error signal which, when amplified, causes an increase in exciter field current resulting in a corresponding increase in rotor current and generator output voltage. Conversely, load reduction will cause the generator voltage to suddenly increase, and in this case the amplified error signal will cause a reduction in exciter field current resulting in a corresponding reduction in rotor current and generator output voltage. Because of the high inductance of the generator field windings, it is difficult to make rapid changes in field current. This introduces a considerable 'lag' in the control system which makes it necessary to include a stabilising circuit in the AVR to prevent instability and optimise the generator voltage response to load changes. Without a stabilising circuit, the regulator would keep increasing and reducing excitation and the line voltage would continuously fluctuate above and below the required value. Modern voltage regulators are designed to maintain the generator line voltage within better than +I% ol nominal for wide variations of machine load. b

--i 01 01 (A) ~ ~ v c n c l p l doc e s

-

. -

Q Brush Eleclncal Macnmes Lld 2002

4

PARALLEL OPERATION 4.1

Quadrature Current Com~ensation As mentioned earlier when a generator is connected in parallel with another power system it may be incapable of significantly influencing the system line voltage, with the level of excitation now determining the reactive power developed by the generator. If line voltage were less than that called for by the voltage regulator, it would supply maximum available excitation in an attempt to increase line voltage and excessive lagging reactive line current would flow. Similarly, if line voltage were high, excitation would be reduced to zero in an attempt to reduce line voltage, and excessive leading line current would flow. Under such circumstances the generator could pole slip (run asynchronously) if any significant power were flowing. A standard method of overcoming the above problem is to modify the voltage control system so that as lagging reactive load on the generator increases, the line voltage that the regulator demands is reduced as shown in Figure 7 in which it will be seen that as the system voltage falls from level A to level B the lagging reactive current increases. For a fixed line voltage,, generator reactive current may be varied by adjustment of the voltage setting potentiometer which adjusts the position of the AVR characteristic. GENERATOR LINE VOLTPGE CHARACTERlSllC

A& B REPRESENT W O SYSTEM VOLTPGES

4 LEADING

b 0

LAGGING REACTlM CURRENT

A method of achieving the above AVR characteristic is known as Quadrature Current Compensation (QCC). A voltage proportional to one line current is added to the voltage across the other two lines and the amplitude of the vector sum is regulated by the AVR as illustrated in the following diagram. b



I

-BRUSH

B E M Ltd.-


1i

MODULAR AUTOMATIC VOLTAGE fl REGULATOR (MAVR) PRINCIPLES I Issue: A I Date: September 2002

.. I

.

a * .

Page: 9 of 12

SCHEMATIC DIAGRAM I h

A M A

b b b

"1

Am

VECTOR DIAGRAMS

C

B Figure 8: Quadrature Current Compensation

It will be seen that the sensing voltage, V,, is the vector sum of line voltage and a voltage proportional to the line current signal. Vc. If line voltage is much greater than Vc, the following approximation way be made.

V1= VBA+ Vc sin @ where @ is the phase angle. Thus as lagging reactive load increases, so does the last term of the above expression which is proportional to reactive current, and therefore line voltage is reduced as the AVR acts to maintain V, constant. For leading reactive currents, line voltage is increased. The reduction in line voltage for rated current at zero power factor lagging is typically 5%. Provided line voltage does not vary, reactive current will be controlled to a level determined by the voltage setting potentiometer of the AVR. If, however, line voltage varied appreciably, an Operator would have to continually adjust the potentiometer to prevent excessive lagging or leading currents. Under such circumstances it may be desirable to use an automatic reactive current or power factor control system. b 5.01.01 (A) MAVR Principles.doc


1

4.2

Machines In Parallel Where a number of machines are operated in parallel, it is usual to adjust the regulators to give a similar amount of droop. This will ensure that the total VAR loading on the system remains reasonably balanced between generators. If droop settings are not equal, the machine with the least droop will tend to take more than its share of the load VARs. This means that the set with least droop will run at a lower lagging power factor than the others.

m3 TOTAL VPRS (SET BY LOAD)

A

C

B

ABBHAM EWAL DROOP

C HAS LESS DROOP THANA&B

VOLTKE

A

A&B I I

LEAD

0

LAG

VmOn

A&B

VARs On C

b VARs

Figure 9: Three Machines In Parallel On Independent Load In the above diagram, machines A and B have identical droop and at a particular line voltage will supply equal VARs. Machine C has less droop and will therefore supply more VARs than A or 6,at the same line voltage. When a machine operates in parallel with an infinite busbar as shown in the following diagram, the busbar behaves like a machine with zero droop, therefore if the busbar voltage remains constant, the generator will produce constant VARs. t

I

-BRUSH

1i

MODULAR AUTOMATIC VOLTAGE P REGULATOR (MAVR) PRINCIPLES I Issue: A I Date: September 2002

B E M Ltd.-


* .

I

.

I..

Page: 11 of 12

is---

INFINITE BUSBAR

A

GENERATOR VOLTAGE

x

INCREASING

AM3 SET POINT

--->t

SYSTEM VOLTAGE

-

--..----___

---___ ---___ ----___

Y Y

CHARACTERISTIC OF MACHINE A

b LEAD

0

LAG

VMs

Figure 10: Machine In Parallel Wlth Infinite Busbar To adjust the VARs on the machine it is necessary to raise or lower the position of line X-Y by adjusting the AVR datum. This is the usual method of manually adjusting VARs or Power Factor. t

4.3

Governor Droop When operating in parallel the prime mover fuel control system is also Changed from a constant frequency control system to one which can operate when the frequency is determined by the grid system. A simple arrangement often used is known as governor droop where the governor speed datum is reduced as the load increases. SPEED (FREWEW

INCREASING ~EQKRSETPOI~ S Y r n ----------__.._____.----

POWER

0

103%

Figure 11: Governor Droop Characteristic In this simple arrangement the system frequency determines the point on the characteristic, and adjustment of the governor datum will raise or lower the line Y-Y and allow the load to be adjusted. As in generator controls, wide variations of system frequency would give rise to large power variation and in such cases it would be normal to include an automatic load control system in the governor. t

15.01.01 (A) MAVR Pnnciples.doc


MODULAR AUTOMATIC VOLTAGE REGULATOR (MAVR)

-BRUSH

€3 E M Ltd.-

f&ning

Module: 05.01.01

i

I

Issue: A

THE GENERATOR CAPABILITY DIAGRAM The generator capability diagram or operating cnart is a convenient method of indicating the operatins conditions of a generator in relation to the various constraints which apply. WATTS

--125

.0.95

0.8,

C

I

LEAD

1 .

I

75

50

25

UNDEREXCITED

0

VARS

I

25

50

75

!

, I

looLAG

OVEREXCITED

Figure 12: Typical Generator Capability Diagram Section A of the curve indicates the reactive limit necessary to prevent overheating of the excitation windings. Section B indicates the limit placed by rated stator current. Section C indicates the underexcitation limit. With excitation levels below this the machine may no1 develop enough synchronising torque to remain in step with the system and may pole slip. A further limit which can be indicated on the diagram is the power limit which corresponds to the

maximum rating of the prime mover. It is normal for the power rating of a prime mover and the generator to increase at lower ambienl temperature and different sets of curves can be drawn on the diagram which correspond to differenl ambient temperatures. Modern voltage regulators have control circuits included which automatically prevent excitation being increased to a level which would cause the excitation wi'ndings to overheat and also prevent the excitation from being reduced to a level which would cause danger of pole slipping. It is also quite normal for the voltage regulator to include facilities for automatic control of power factor and reactive VA. Governors fitted to the prime movers usually have control circuits which limit the machine output power according to ambient temperatures, or other parameters associated with the prime mover. F

5.01 .O1 (A) MAVR Principles.doc


Brush Turbo-generator (Alternator) Training Course

Recommend Documents