173-Gas Substations Project Guide

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QSV 81-91G Gas Power Plant Project Guide

Page 1Issue 2.0 / March.2001

Technical data contained in this publication is not contractual and may change without prior notice.

Foreword

This Power Plant Project Guide

describes CHP power plants and gas

fueled power plants built around our new

generation of lean-burn gas engines.

The project guide is intended for use in

presale activities and also as support

for final design of power plants from 1

to 20 MW.Parts of this document, such as

equipment description and auxiliaries

data sheets may be reproduced and

disclosed to clients.

The content of this document is based

on the most current information at the

time of publication and is subject to

change without notice.

Cummins Power Generation

Manston Park

Columbus Avenue

Manston

Ramsgate

Kent

CT12 5BF

U.K.

Telephone +44 (0) 1843 255 000


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Page 2 Issue 2.0 / March.2001


Gas Power Plant Project Guide QSV 81-91G

Contents

Foreword 1

1. General 6Introduction ....................................................... 6

Quality assurance .............................................. 6

World electricity supplies.................................. 7

Standards .......................................................... 10Prime movers..................................................................10

Generators ......................................................................10

Electrical Equipment .....................................................10

2. Generating sets 11

Reference conditions...................................................... 11De-rate factors ................................................................ 11

Gas engine 11Engine components ........................................................ 11

Engine block ................................................................... 11

Cylinder head ................................................................. 11

Crankshaft......................................................................12

Connecting rod ...............................................................12

Main bearings and conrod big end bearing ................12

Cylinder liner .................................................................12

Piston...............................................................................12Piston rings ..................................................................... 12

Camshaft and valve mechanism ...................................12

Flywheel housing............................................................13

Free end cover ................................................................13

Oil sump..........................................................................13

3 Combustion 14QSV 81-91G design: open chamber .............................14

Exhaust Gas composition ..............................................15

Combustion process .......................................................15

4 Gas Definition 16Heat value .......................................................................16

Gas density .....................................................................16

Methane number............................................................16

Current Methane Numbers (MN) ................................16

Natural gas .....................................................................17

Gas quality requirements ..............................................17


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5 Engine Lubricant & Coolant Definition 18Lube Oil Definition........................................................18

Lube Oil Quality ............................................................18

Lube Oil Grade (weight) ...............................................18Coolant Treatment ........................................... 19General ...........................................................................19

Water or Coolant & Inhibitors Preparation................20

Antifreeze composition .................................................. 22

6 Boiler Water Treatment 23Boiler Operation ............................................................23

7 Alternator 25General ...........................................................................25

Winding and Electrical Performance...........................25Generator design ............................................................25

Voltage regulator functions ...........................................28

8 Genset Control Panel (GCP) 29Gas engine control .........................................................29

Generator control...........................................................29

GCP System Configuration...........................................30

PC Based H.M.I. (Touchscreen) ...................................30

PowerCommand Supervisor.....................................31

AC Generator protection devices .................................32

9 Generator Load Acceptance 3310 Generator Set Arrangement 34Generator Set Connections ...........................................35

11 Generator Set Handling 36

12 Turnkey Power Plant 38Power Plant Buildings (General) ..................................38

11 Safety Equipment 38Fire, Smoke and Gas Leakage Detection. ....................38

Electromagnetic Interference........................................39

13 Generator set foundations 39

14 Maintenance facilities 39

15 Electrical systems 40Baseload applications ....................................................41

Isolated System - Medium Voltage Generation ...........42

Power distribution equipment ......................................43

Neutral Grounding System ...........................................44


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16 Power Plant Control Features 45

17 Low voltage supplies 47

18 Power Plant Earthing System 48Typical Earthing Arrangement.....................................4919 Mechanical systems 50Starting system ...............................................................51

Lubricating oil system ...................................................52

Cooling systems

(without heat recovery) ............................................. 53

Cooling systems

(with heat recovery) ..................................................53

Radiator system..............................................................54

Raw water system ..........................................................55Tower system ..................................................................56

20 Charge air system 58

21 Exhaust gas system

(without cogeneration system) 59

22 Ventilation and noise control 60Sizing ...............................................................................60

Noise control ...................................................................60

23 Cogeneration systems 61Key drivers and competitive advantages .....................61

Basic knowledge .............................................................61

24 Partnership 62Engineering ....................................................................62

Maintenance ...................................................................62

Operation of the power plant........................................62

25 Units,Formulae 63Power imperial measurements ......................................63

Energy measurements ...................................................63Refrigeration ..................................................................63

Conversion factors .........................................................64

Area .................................................................................65

Volume ............................................................................65

Mass ................................................................................65

Force ................................................................................65

Pressure, stress ...............................................................65

Temperature ...................................................................66

Power ..............................................................................66


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Energy .............................................................................66

Specific energy (mass) ................................................... 66

Specific energy (volume) ...............................................67

Specific heat capacity (mass) ........................................67Specific heat capacity (volume) ....................................67

Water hardness ..............................................................67

Miscellaneous ................................................................. 67

Formulae.........................................................................68

26 Mechanical data 69QSV 81-91G gas regulating unit ...................................69

Compressed Air Production Unit .................................70

Air Storage Unit .............................................................71


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Quality assurance

The quality of the products is ensured by a quality

assurance program, as described in Quality Assurance

Manual and Quality Instructions.

These meet the requirements of the ISO 9001 International

Quality Standard. All activities in the operations are

evaluated and revised continuously through internal and

external quality reviews.

Cummins develops and maintains a world-wide, high

quality service network which ensures optimum operation

of delivered products under all circumstances by means

of preventive and corrective service, spare parts supply,

training of operating staff and technical support and infor-

mation.

1. General

Introduction

The Cummins QSV 81G-91G gas engines, built in the

United Kingdom, are used as prime movers for gas fuelled

power plants and are designed for powering:

- Cogeneration plants in sensitive environmental

areas;

- Cogeneration plants for hospitals, office

complexes and factories;

- Power plants for IPP (Independent Power

Producers) and industrial parks.

- Power from Flare Gas

- Power from Waste Flammable Gases

The Cummins turnkey solutions are designed for low

capital investment with reduced lead-times, ideally suited

to satisfying short and long term needs.

When designing power plants, fundamental design

information is important.

Environmental conditions such as noise level, emissions

and pollution will affect the design parameters and the

elements and ground conditions may impact the overall

scheme.

This document is intended to give guidance in the proper

application of the product. For more detailed assistance,

contact the Cummins Power Generation at Manston

England.


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World electricity suppliesCountry Frequency (Hz) Supply Voltage Levels in Common Use (V)Abu Dhabi (United Arab Emirates) 50 11 kV;415/250

Afghanistan 50; 60 380/220; 220

Algeria 50 10 kV; 5.5 kV; 380/220; 220/127

Angola 50 380/220; 220

Antigua 60 400/230; 230

Argentina 50 13.2 kV; 6.88 kV; 390/225; 339/220: 220

Australia 50 22 kV; 11 kV; 6.6 kV; 440/250; 415/240; 240

Austria 50 20 kV; 10 kV; 5 kV; 380/220; 220

Bahamas 60 415/240; 240/120; 208/120; 120

Bahrain 50; 60 11 kV; 400/230; 380/220; 230; 220/110

Bangladesh 50 11 kV; 400/230; 230

Barbados 50 11 kV; 3.3 kV; 230/115; 200/115

Belgium 50 15 kV; 6 kV; 380/220; 2201127, 220

Belize 60 440/220; 220/110

Benin (Dahomey) 50 15 kV; 380/220; 220

Bermuda 60 4.16/2.4 kV; 240/120; 208/120

Bolivia 50; 60 230/115; 400/230/220/110

Botswana 50 380/220;220

Brazil 50; 60 13.8 kV; 11.2 kV; 380/220,220/127Brunei 50 415/230

Bulgaria 50 20 kV; 15 kV; 380/220; 220

Burkina-Faso (Upper-Volta) 50 380/220; 220

Burma 50 11 kV; 6.6 kV; 400/230; 230

Burundi

Cambodia (Khmer Republic) 50 380/220; 208/120; 120

Cameroon 50 15 kV; 320/220; 220

Canada 60 12.5/7.2 kV;4,16 kV 600/347; 240/120; 208/120; 600; 480; 240

Canary Islands 50 380/220; 230

Cape Verde Islands 50 380/220; 127/220

Cayman Islands 60 480/240; 480/227; 240/120; 208/120

Central African Republic 50 380/220

Chad 50 380/220; 220

Chile 50 7.2 kV;380/220; 220Christmas Islands

Colombia 60 13.2 kV; 240/120; 120

Congo-democratic Republic of (Zaire) 50 380/220; 220

Congo-Republic of 50 380/220; 220

Costa Rica 60 240/120; 120

Cuba 60 440/220; 220/110

Cyprus 50 11 kV; 415/240; 240

Czechoslovakia 50 22 kV; 15 kV; 6 kV; 3 kV; 380/220; 220

Denmark 50 30 kV; 10 kV; 380/220; 220

Dominica (Windward Islands) 50 400/230

Dominican Republic 60 220/110; 110

Dubai (United Arab Emirates) 50 6.6 kV; 330/220; 220

Ecuador 60 240/120; 208/120; 220/127; 220/110

Egypt (United Arab Republic) 50 11 kV; 6.6 kV; 380/220; 220

Eire (Republic of Ireland) 50 10 kV; 380/220; 220El Salvador 60 14.4 kV; 2.4 kV; 240/120

Ethiopia 50 380/220; 220

Faeroe Islands (Denmark) 50 380/220

Falkland Islands (UK) 50 415/230; 230

Fiji 50 11 kV; 415/240; 240

Finland 50 660/380; 500; 380/220; 220

France 50 20 kV; 15 kV; 400/230; 380/220; 380; 220;

French Guiana 50 380/220

French Polynesia 60 220; 100

Gabon 50 380/220

Gambia 50 400/230; 230

Germany (BRD) 50 20 kV;10.5 kV; 10 kV; 6 kV; 400/230; 380/220; 220

Germany (DDR) 50 10 kV; 6 kV; 660/380; 380/220; 220/127; 220; 127


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Country Frequency (Hz) Supply Voltage Levels in Common Use (V)Ghana 50 440/250; 250

Gibraltar 50 415/240

Greece 50 22 kV; 20 kV; 15 kV; 6.6 kV; 380/220

Greenland 50 380/220

Grenada (Windward Islands) 50 400/230; 230

Guadeloupe 50; 60 20 kV; 380/220; 220

Guam (Mariana Islands) 60 13.8 kV; 4 kV; 480/277; 480: 240/120; 207/120

Guatemala 60 13.8 kV; 240/120

Guyana 50 220/110

Haiti 60 380/220; 230/115; 230; 220; 115

Honduras 60 220/110; 110

Hong Kong (and Kowloon) 50 11 kV; 346/200; 200

Hungary 50 20 kV; 10 kV; 380/220; 220

Iceland 50 380/220; 220

India 50; 25 22 kV; 11 kV; 440/250; 400/230; 460/230; 230

Indonesia 50 380/220; 2201127

Iran 50 20 kV; 11 kV; 400/231; 380/220; 220

Iraq 50 11 kV; 380/220; 220

Israel 50 22 kV; 12.6 kV; 6.3 kV; 400/230; 230Italy 50 20 kV; 15 kV; 10 kV; 380/220; 220/127; 220

Ivory Coast 50 380/220; 220

Jamaica 50 4/2.3 kV; 220/110

Japan 50; 60 6.6 kV; 200/100; 22 kV; 6.6 kV; 210/105; 200/100; 100

Jordan 50 380/220; 220

Kenya 50 415/240; 240

Korea Republic (South) 60 200/100; 100

Kuwait 50 415/240; 240

Laos 50 380/220

Lebanon 50 380/220; 190/110; 220;110

Lesotho 50 380/220; 220

Liberia 60 12.5/7.2 kV; 416/240; 240/120; 208/120

Libyan Arab Republic 50 400/230; 220/127; 230;127

Luxembourg 50 20 kV; 15 kV; 380/220; 220Macao 50 380/220; 220/110

Malagassy Republic (Madagascar) 50 5 kV; 380/220; 220/127

Malawi 50 400/230; 230

Malaysia (West) 50 415/240; 240

Mali 50 380/220; 220/127; 220; 127

Malta 50 415/240

Manila 60 20 kV; 6.24 kV; 3.6 kV; 240/120

Martinique 50 220/127; 127

Mauritania

Mauritius 50 400/230; 230

Mexico 60 13.8 kV; 13.2 kV; 480/277; 220/127; 220/120

Monaco 50 380/220; 220/127; 220; 127

Montserrat 60 400/230; 230

Morocco 50 380/220; 220/127

Mozambique 50 380/220

Muscat and Oman 50 415/240; 240

Naura 50 415/240

Nepal 50 11 kV; 400/220; 220

Netherlands 50 10 kV; 3 kV; 380/220; 220

Netherlands Antilles 50; 60 380/220; 230/115; 220/127; 208/120

New Caledonia 50 220

New Zealand 50 11 kV; 415/240; 400/230; 440; 240; 230

Nicaragua 60 13.2 kV; 7.6 kV; 240/120

Niger 50 380/220; 220

Nigeria 50 15 kV; 11 kV; 400/230; 380/220; 230; 220

Norway 50 20 kV; 10 kV; 5 kV; 380/220; 230


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Country Frequency (Hz) Supply Voltage Levels in Common Use (V)Pakistan 50 400/230; 230

Panama 60 12 kV; 480/227; 240/120; 208/120

Papua New Guinea 50 22 kV; 11 kV; 415/240; 240

Paraguay 50 440/220; 380/220; 220Peru 60 10 kV; 6 kV; 225

Philippines 60 13.8 kV; 4.16 kV; 2.4 kV; 220/110

Poland 50 15 kV; 6 kV; 380/220; 220

Portugal 50 15 kV; 5 kV; 380/220; 220

Portuguese Guinea 50 380/220

Puerto Rico 60 8.32 kV; 4.16 kV; 480; 240/120

Qatar 50 415/240; 240

Reunion 50 110/220

Romania 50 20 kV; 10 kV; 6 kV; 380/220; 220

Rwanda 50 15 kV; 6.6 kV; 380/220; 220

Sabah 50 415/240; 240

Sarawak (East Malaysia) 50 4151240; 240

Saudi Arabia 60 13,8 kV; 380/220; 220/127; 127

Senegal 50 220/127; 127

Seychelles 50 415/240Sierra Leone 50 11 kV; 400/230; 230

Singapore 50 22 kV; 6.6 kV; 400/230; 230

Somali Republic 50 440/220; 220/110; 230: 220; 110

South Africa 50; 25 11 kV; 6.6 kV; 3.3 kV; 433/250; 400/230; 380/220; 500; 220

Spain 50 15 kV; 11 kV; 380/220; 220/127; 220; 127

Spanish Sahara 50 380/220; 110; 127

Sri Lanka (Ceylon) 50 11 kV; 400/230; 230

St. Helena 50 11 kV; 415/240

St. Kitts Nevis Anguilla 50 400/230; 230

St. Lucia 50 11 kV; 415/240; 240

Saint Vincent 50 3.3 kV; 400/230; 230

Sudan 50 415/240; 240

Surinam 50; 60 230/115; 220/127; 220/110; 127; 115

Swaziland 50 11 kV; 400/230; 230

Sweden 50 20 kV; 10 kV; 6 kV; 380/220; 220

Switzerland 50 16 kV; 11 kV; 6 kV; 380/220; 220

Syrian Arab Republic 50 380/220; 200/115; 220; 115

Taiwan (Republic of China) 60 22.8 kV; 11.4 kV; 4.16 kV; 380/220; 220/110

Tanzania (Union Republic of) 50 11 kV; 400/230

Thailand 50 380/220; 220

Togo 50 20 kV; 5.5 kV; 380/220; 220

Tonga 50 11 kV; 6.6 kV; 415/240; 240; 210

Trinidad and Tobago 60 12 kV; 400/230; 230/115

Tunisia 50 15 kV; 10 kV; 380/220; 220

Turkey 50 15 kV; 6.3 kV; 380/220; 220

Uganda 50 11 kV; 415/240; 240

United Kingdom 50 22 kV; 11 kV; 6.6 kV; 3.3 kV; 400/230; 380/220; 240; 230; 220

Uruguay 50 15 kV; 6 kV; 220

USA 60 480/277; 208/120; 240/120USSR (former republics of) 50 380/230; 220/127 and higher voltages

Venezuela 60 13.8 kV; 12.47 kV; 4.8 kV; 4.16 kV; 2.4 kV; 240/120; 208/120

Vietnam (Republic of) 50 15 kV; 380/220; 208/120; 220; 120

Virgin Islands (UK) 60 208; 120

Virgin Islands (US) 60 110/220

Western Samoa 50 415/240

Yemen-Northern (Sana'a) 50 440/250; 250

Yemen-Southern (Aden) 50 400/230

Yugoslavia 50 10 kV; 6.6 kV; 380/220; 220

Zambia 50 400/230; 230

Zimbabwe 50 11 kV; 390/225; 225


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Standards

Our equipment is designed and manufactured in accordance

with the following International Standards Codes:

Prime movers

ISO 3046 (BS 5514 ) - Specification for reciprocatinginternal combustion engines, parts 1 to 6.

ISO 8528 Reciprocating internal combustion engine driven

alternating current generating sets, parts 1 to 10

EEC Directive 84/536/EEC - Noise from construction

equipment - power generators.

The engine and its auxiliaries are manufactured and/or

controlled under a registered quality control system ap-

proved to ISO 9001.

Generators

IEC 34-1 Rotating electrical machinesBS2615 The Electrical Performance of Rotating Electrical

Machinery

BS 4999(IEC 341) General requirements for rotating

electrical machines.

BS 5000(IEC 341)Rotating electrical machines of particu-

lar types or for particular applications.

NEMA MG 1 Motors and generators

EN 50081(BS EN 500812)Electromagnetic compatibility.

Generic emission standard.

EN 50082(BS EN 500822)Electromagnetic compatibility.Generic immunity standard.

The generator and its control system are manufactured under

a registered quality control system approved to ISO 9001.

Electrical Equipment

IEC 4391(BS EN 60439)(EN 604392) Specification for

low-voltage switchgear and control gear assemblies.

IEC 9471(BS EN 60947)(EN 609472) Specification for low

voltage switchgear and control gear.

IEC 3641(BS 7671) Requirements for electrical installa-

tions. IEE Wiring Regulations (sixteenth edition).

EC 439(BS 5486) Factory Built assemblies of Low Voltage

Switchgear and Control Gear.

EC 479 Effects of Current Passing through the Human Body

BS3950 Electrical Protective Systems for A.C Plant

BS 159 1957 Busbars and Busbar Connections.

BS 162 1661 Electrical Power Switchgear

and Associated Apparatus.

BS 2757 Insulation

BS 5424 Part 1 1977 - Contractors.


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2. Generating sets

Reference conditions

The output of the engines conforms to ISO 3046/1. Where

ambient conditions exceed the reference conditions the

engine will de-rate for temperature and altitude at the rates

defined in the data sheets.

COP refers to engine operating for baseload duty with a

continuous 100% load.

No overload is permitted.

Prime duty refers to operation in island mode with a

fluctuating load where the average load factor is 75%.

De-rate factors

The performance of gas engines is affected by the reduction

in oxygen mass entering the cylinders at altitudes and higher

temperatures. The output rating is set at 1000 metres and

35C respectively. Where the engine draws its aspiration

air from inside a building or enclosure the effect of the rise

in temperature due to the heat rejection from engine block,

alternator carcass, exhaust and cooling pipework must be

taken into consideration.

The quality of the gas is another factor which will cause

the engine output to be de-rated. The engines have different

variants, with the same standard power output, which willoperate on a methane index from 50 upwards. You should

consult Cummins Power Generation at Manston England

for guidance on operation on a gas with a methane index

below 50.

The low temperature cooling circuit is designed for a return

temperature of 50C. It is permissible for this temperature

to increase to 60C but the engine output will be de-rated.

You should consult Cummins Power Generation at Manston

England for guidance on the de-rate factor.

Gas engine

Engine components

The engines are four stroke high speed, spark ignited leanburn gas engines. Lean burn design increases performance

and reduces emissions. All main auxiliaries and ducts

are integrated, allowing easy maintenance by large inspec-

tion doors.

Engine block

The engine block is cast in one piece in modular cast iron.

It has a stiff and durable design to absorb internal forces

and to enable resilient mounting.

The engine has an underslung crankshaft held in place by

main bearing caps. The main bearing caps are nodular

cast iron and are guided laterally by the engine block andaxially by a locating pin. They are fixed by two

hydraulically pretensioned studs and secured by lateral

screws.

The supercharge air duct is integrated between the

cylinder banks disposed in a V angle of 60. The jacket

cooling water supply to the cylinder heads and the return

are integrated in the engine block.

The lubricating oil supply to the bearings and the piston

cooling occurs through a drilled channel in the middle of

the engine block.

There is one camshaft for each of the two cylinder banksbearing valve cams. The bearing housings are fully

integrated into the engine block and located on the outside

of the cylinders. There are large crankcase openings

as well as openings for the camshafts on both sides of

the engine block.

Cylinder head

The cylinder head is made of special cast iron. The

thermally loaded flame plate is efficiently water cooled.

The intermediate deck improves the cylinder head cool-

ing as well as absorbing the mechanical loads on the cyl-

inder head. The high and stiff design of the cylinder head

allows it to be fixed by only four hydraulically tightened

studs.

The cylinder head features two inlet and two exhaust

valves per cylinder. The exhaust valve seat is water cooled.

The valves have stellite-coated seat faces and chromium-

plated stems.


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Cylinder liner

The cylinder liner is made of centrifugally cast, cast iron,

and surface finished by lapping. The jacket water is sealed

by two O-rings in the lower part, and a metal to metal seal

face under the mating flange. An anti-polishing ring is in-serted at the top of the liner, allowing heavy duty opera-

tion with minimised wear.

Piston

Piston is made of a steel open combustion chamber and an

aluminium skirt. The piston cooling is from oil nozzles

fed by the main oil duct of the cylinder block. The piston

ring grooves are hardened.

Piston rings

The piston ring set includes two chromium plated com-

pression rings and one spring loaded oil scraper ring. All

piston rings are situated in the steel crown.

Camshaft and valve mechanism

The camshafts are made up of sections, which are flanged

together. The cam profiles and bearing surfaces are case

hardened. The camshaft turns in bushings force-fitted into

the engine block. The valve tappets are of piston and roller

type and are located in the housing for the spark controldevices.The camshaft drive is fully integrated into the en-

gine block, at the flywheel end.

Crankshaft

The crankshaft is forged in one piece in a high tensile steel.

All the crankshaft surface is nitrided. Journals and crankpins

end on recessed fillets.

The crankshaft fulfils all classification societies requirements.

The two counterweights per crankthrow are each bolted on

by three screws. They are positioned by locating pins which

prevent any fretting corrosion.

The main drive crankshaft pinion is shrunk on the flywheel

end, to drive camshafts. Correct toothing allows operation

without axial efforts on thrust bearings. The gear wheel for

coolant, lubricating oil pump drive, and torsional vibration

damper are bolted on to the free end.

Connecting rod

The connecting rod is forged in one piece and the big end has

a serrated split. The cap is hydraulically tightened by two studs.

The connecting rod passes through the liner for maintenance.

The cap is installed and tightened from the side where the

cylinder is situated, opening one inspection door. The oil sup-

ply for the small end bush lubrication passes through a drill-

ing in the connecting rod.

Main bearings and conrod big end bearing

The main bearing consists of two thin prefinished bearingshells. Both shells are peripherally slightly longer than the

housing thus providing the shell fastening and seating.

The main bearing located closest to the flywheel is provided

with four thrust washers for the axial guidance of the

crankshaft. The flywheel is bolted and secured by pins on

the crankshaft end.

conrod


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Flywheel housing

The flywheel housing includes several functions. It sup-

ports the flange mounted generator as well as starter, bar-

ring devices, some governing accessories and ducts.

Free end cover

The torsional vibration damper is fully enclosed in the

free end cover. All engine driven pumps are installed on

the free end cover. There are, as standard, the twin cooling

water pump and the pump unit including engine driven

main lubricating oil pump and electric pre-lubricating

pump.

Oil sump

Oil sump is bolted under cylinder block. Its capacity is

intentionally increased in relation to engine power,

allowing the oil charge intervals to be extended.


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3 Combustion

Combustion is a chemical reaction between fuel and oxy-gen. If the amount of air brought into the cylinder is perfect

for complete combustion of the fuel, then the combustion

is called stoichiometric i.e. complete.

If an excessive amount of air is introduced, the combus-

tion is called lean.

Lean burn engines benefit from lower combustion

temperatures and a consequent reduction in the formation

of nitrogen oxides (NOx )

The characteristic of lean burn air-fuel ratio is called

lambda l, defined from following formula:

l= (m air/ m gas) actual

(m air/ m gas) stoichiometric

QSV 81G-91G engines are spark ignited and operate with

a lean-burn.

QSV 81-91G design: open chamber

The design comprises a simple open combustion chamber,

housed in the piston crown. The flame plate of cylinder

head is regular, the spark plug is centrally located. Air and

gas is mixed prior to the turbocharger, using a governorcontrolled gas nozzle operating in a venturi. The fuel - air

mixture is controlled at l = 1.7QSV 81 G top section view


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Exhaust Gas composition

Exhaust gas composition will depend upon fuel gas

composition and combustion fuel to air ratio.

The table below depicts the exhaust gas composition for pure

methane as the fuel gas controlled at l = 1.7

Diagram of combustion limits

Combustion process

Any chemical reaction requires an energy source to initiatecombustion. The spark plug performs this function. For

engines operating on the pre-chamber principle the

combustion process is enhanced by the pre-mixing of air

and fuel thereby injecting a more concentrated mixture

into the combustion chamber. This controls the speed of

ignition and reduces the occurrences of knocking, also

known as detonation.

Knocking (detonation) occurs, either when the air/fuel

blend comes into contact with the hot parts of the

combustion chamber and self ignites or, as a result of

ignition taking place at excessive speed. Combustion

becomes noisy and harmful shocks are exerted on to thepiston, rod and crankshaft.

To prevent knocking, the combustion process must be

controlled to keep within the optimum operating window.

Charge air temperatures and volume, together with air to

fuel ratio and compression ratio, are constantly

monitored. The microprocessor based engine controller

regulates the fuel flow and air/gas mixture and the ignition

timing to prevent knocking.

Gas c om ponent Form ula Cont ent vol-%

Nitrogen N2 72.70%

Oxygen O2 8.10%

Water vapour H2O 13.70%

Carbon dioxide CO2 5.50%

Molecular weigh kg/kmol 28Density kg/Nm3 1.24

Specific heat cp 120-450 C 1.10 kJ/(kg K)

Spec ific heat cp 25-120 C 1.05 kJ/ (kg K)


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G as Form ulaMethane

N um ber

M ethane C H4 100

E thane C 2H 6 44

P ropane C 3H 8 33

B utane C 4H 10 10

C arbon m onoxide C O 75

H yd rogen H 2 0

Heat values are sometimes given in kWh/Nm3 or MJ/Nm3

or MJ/Sm3 (e.g. in Italy) or BTU/SCF (in the US). Notethat standard (S) refers to an ambient temperature of 15

oC.

(e.g. 1 Sm3=(273+15)/273 Nm3=1.055 Nm3)

Gas density

Fuel gas density is dependent on gas composition and

varies from case to case. It is a function of temperature

and decreases for increasing temperature. Usually,

references to gas density assume normal conditions of

0C and 101.3 kPa unless otherwise specified. Gas density

is expressed in kg/Nm3 (SI-unit).

Methane number

Methane number (MN), sometimes called methane index,

can be assigned to any gaseous fuel indicating the

percentage by volume of methane blend with hydrogen

that exactly matches the knock intensity of the unknown

gas mixture under specific operation conditions in a knock

test engine.

Therefore, the MN gives a scale for evaluation of the

resistance to knocking of a gaseous fuel. The Methanenumber can be used to determine fuel gas suitability as an

engine fuel. MN is an index and has no units.

Current Methane Numbers (MN)

Most natural gases have methane numbers from 70 to 97.

Incombustible gases like CO2

and N2

also increase the

MN.

4 Gas Definition

Gaseous fuel is a mixture of combustible and inert gases

which have different physical properties. Many of thefuel gas properties can be determined from those of the

component gases.

The table below gives some physical characteristics of

gases contained in natural gas.

N = normal, and is at an ambient temperature of 0C,at a pressure of 101.3 kPa gauge.

Heat value

The heat value of the fuel is a measure of its energy

content. When dealing with the QSV engines, the lower

heat value (LHV) is used when presenting fuel con-

sumption and efficiencies. Normally, the value is given

in MJ/Nm3 (SI-unit).

Sometimes natural gas suppliers give sales unit price

per energy unit at higher heat value (HHV). Use of the

HHV gives a seemingly lower fuel price.

As HHV includes the vaporization or latent heat of the

generated vapour there is a relation between HHV and

LHV:

LHV/HHV=0.9 or

HHV=LHV + water mass * vapourization enthalpy.

Gas Formula Mol weight LHV Density

kg/kmol MJ/Nm3

kg/Nm3

Methane CH4 16,0 35,3 0,71

Ethane C2H6 30,1 63,5 1,34

Propane C3H8 44,1 90,0 1,99

Butane C4H10 58,1 117 2,63Pentane C5H12 72,1 144 3,30

Hexane C6H14 86,2 165 4,44

Heptane C7H16 100 190 5,15

Octane C8H18 116 216 5,86

Hydrogen H2 2,02 10,6 0,09

Carbon dioxide CO2 44,0 0 1,95

Carbon monoxide CO 28,0 12,5 1,23

Oxygen O2 32,0 0 1,41

Nitrogen N2 28,0 0 1,23

Hydrogen sulphide H2S 34,1 23,1 1,52


17/72




Gas unit/formula criteria

Gas heat value(LHV) MJ/Nm3 30-40

Gas density kg/Nm3 0,7-0,9

Methane number MN >70

Methane content CH >75%

Ethane C2H

6


18/72




Other Lubricants

From time to time, other oils will be approved and added

to the list, where a specific oil is specified, contact

Cummins Power Generation at Manston England.

5 Engine Lubricant & Coolant

Definition

Lube Oil Definition

High-quality lubricants shall be used for the lubrication of

QSV 81G-91G engines. Products from well-known

companies who can assure a consistent supply of quality

oils, and who can also provide oil analysis from engines in

operation, are preferred.

The selected oil must have enough heat resistance not to

form ash deposits at the temperature to which it is exposed.

It must also maintain a satisfactory oil film between the

moving components.

Lube Oil Quality

The gas engine lube oils are specially formulated.Never use

a diesel engine lubricant in a gas engine as it could cause

damage to the engine.

The gas engine oil contains adequate additives to prevent

the lubricant base being degraded by high temperatures and

water vapour. Oils listed below are defined as suitable for

use in Cummins natural gas lean burn engines.

TBN of regular gas engines lubricants is near 5. It is sufficient

to prevent bearing corrosion against most natural gases whose

H2S content is below 0.01% in volume. Above this, gas treat-ment or special lube oil formulation is recommended.

A TBN over 6 may cause piston fire ring blocking due to

excessive calcium deposits in the grooves. For the same

reasons, sulphated ash content of oil should be lower than

0.5%.

Lube Oil Grade (weight)

A monograde SAE 40 is required, as a minimum weight.

This is necessary to ensure oil film resistance under high

temperature operation.

ProducerBrand name & characteristics

For continuousduty

grade TBNsulphated

ash%

Engines operated with natural gas,H

2S content< 0.01 vol.

MOBIL Pegasus 805 SAE 40 6.2 0.50

MOBIL Pegasus 705 SAE 40 5.3 0.46

ELF Nateria MH 40 SAE 40 5.2 0.45

SHELL Mysella LA SAE 40 5.0 0.45

ESSO( EXXON) Estor SHPC SAE 40 5.1 0.48


19/72




Coolant TreatmentGeneral

CHP systems comprise various water loops whose

operating conditions are different. To safeguard the enginelongevity it is better to separate the engine water system

from the other water loops, This allows close control of

the engine cooling water condition.

The steam boiler water treatment is peculiar to the boiler,

and should never be circulated in the engine.

The purposes of water treatment are to prevent:

- Furring of heat exchange surfaces due to the mineral

content of the water,

- Corrosion of metals due to dissolved oxygen and car-

bon dioxide,

- Cavitation due to boiling point, and/or pump impeller

pressure drop,

- Freezing if coolant & engine is exposed to frost.

We have defined for our CHP plants, a number of

categories of water treatment processes, from existing

commercially available products. Two criteria are pre-

eminent to determine the category of treatment:

- the nature of the materials inside the circuit.

- the highest water circuit wall/surface temperature.

Categories are as follows:

A for anticorrosion products, without antifreeze addition

B for anticorrosion products with antifreeze addition

C for steam boiler feedwater products

In these categories, two grades are proposed :

- Grade 1 for upgrade products used in severe conditions

in primary circuits;

- Grade 2 or 3 for regular products used in secondary

circuits.

Primary circuits are the ones in contact with engine internal

parts, and the exhaust heat exchangers. Secondary cir-

cuits are the heat transfer circuits, not in contact with fired

parts. Tables in Cogeneration Chapter indicate the rec-

ommended product category and grade for each loop ofthe CHP plant.

Upgrade Corrosion Inhibitors

(Category A Grade/-A1)

Engine circuits are to be treated only with recommended

chemical (s), suitable for engine conditions, aluminium

protection and passage through exhaust heat exchangers

(high wall temperature).

Regular Corrosion Inhibitors (A2)

Other circuits which are made of various metals, alu-

minium excepted, may be treated with regular products

of A2 category, if they are not passing through exhaust

heat exchangers, whose wall temperature is high. We

recommend stainless steel plate heat exchangers for engine

HT water and lube oil interface. They can be used in

contact with regular products.

Products which form a protective layer are suitable,

provided that this layer may be cleaned or dissolved if it

tends to reduce the performance of exchangers. Soluble

oils are not recommended.

The Floating anode (Nitrite- chromates) product

demands a precise understanding of metals in the circuit

and a frequent check of concentration. They are either

toxic or unstable and forbidden for use in certain countries.

We do not recommend their use.

Heating Circuit Corrosion Inhibitors (A3

category)

The circuits entirely made of carbon steel, bronze and

passivated copper may be treated with A3 category prod-

ucts. Trisodic phosphate, morpholine or any other

chemical formulated to maintain the PH value over 8,5


20/72




are suitable. This treatment is not suitable where other

metals are present in the engines, or when fluid speed is

over 1m/s.

Upgraded Inhibitor & Antifreeze Coolant for

CHP

(Category B Grade/-B1)

The B1 category coolant is the recommended product for

engine protection and use in exhaust heat exchangers

whose wall temperature is elevated. It is efficient where

aluminium is present. Use of a regular automotive coolant

may cause floculation, deposits, glycol decomposition or

exchanger deterioration.

The proposed ELF Coolelf CHP supra is particulaly

suitable for the CHP plants in hot countries. However,

20% Monoethylene glycol is included, not for freezing,but to dissolve and stabilize the anticorrosion organic

complex.

Engine Inhibitor & Antifreeze Coolant (B2)

The B2 category coolant is the recommended product for

engine protection but not for use in exhaust heat

exchangers, whose wall temperature is elevated. It is

efficient where aluminium is present.

Regular Inhibitor Antifreeze Coolant

(B3 category)The B3 coolant is suitable for hot water loops which are

not passing through the engine and/or exhaust exchanger

and are not in contact with aluminium parts.

Water or Coolant & Inhibitors Prepara-

tion

If concentrated products are used, you have to use good

quality water for coolant preparation or .

The minimum quality requirements for anti-corrosion

product efficiency are :- Water totally clean and limpid.

- Total Hardness < 5.6 dH(1) (100 ppm as CaCo3).

- Acidity 6.5 < pH < 7.5.

- Chlorides contents < 60 mg/liter of NaCl.

- Sulphates contents < 40 mg / liter of SO4CaAbove these figures, use softened or demineralized water,

or ready-to use soloutions.

Basically we recommend the use of demineralized water

for dilution, or ready to use products.

Coolant Preparation

For antifreeze based coolant preparation a maintenance

tank, where water and treatment chemicals are mixed

together is proposed. A pump and piping system to

connect pump, tank, and circuits together for filling,dilution and maintenance can then be designed and

installed. The tank should be sized to hold the circuit

contents.

Rules of Thumb:

- Use of distillated water or rain-water without treatment

is strictly forbidden, even for short duration tests.

- Life-time of antifreezed coolant of grade 1 is about 3

years in air-tight circuits.

- An analysis of coolant quality is recommended every

three months, whatever its nature. Quick-check sets are

available from the chemical suppliers.

-If the cogeneration loop is part of an existing system, it

is advisable to check its cleanliness to prevent central

heat exchanger fouling.

-If new chemical products are installed in existing

systems, it is advisable to flush and thoroughly clean the

systems, to remove all traces of the old chemicals..

-Chosen product shall not be toxic if it is to be used in

heat exchangers through which drinkable water is pass-ing.

Point of Warning

LT water and HT water in the engine circuit shall be pro-

tected using the same chemical, as these circuits are in

mixed inside the engine if the doulble impellor, engine

driven pumps are fitted.(1)A total hardness up to 250 ppm as CaCO

3may be toleratedin the circuit,

but to top-up with this kind of water, to compensate for evaporation in

service would cause deposits or saturate the furring inhibitors.


21/72




Coolant Treatment Definition

The table below defines the kinds of coolants to be used

for safe operation. The ones defined for circulation in

engine and exhaust exchanger shall be mandatorily used

during warranty period. If other coolants should be used,a testing procedure shall be implemented, followed by

corrosion checks, and chemical analysis.

Use of table below:

Product indicated for grade 1 is suitable for use in all

situations. Choice of different grades in a system would

cause unschedulded coolant changes in loops, due to

aging of lower grade coolants. Choose only tested

products, to prevent equipment degradation, loss of time

and money.

Product category working conditionsRecommended brands

substite productsProducer Tradename Type of product

HIGH-GRADE

INHIBITOR

A1

Engine circuits with copper ,

brass, soldering, aluminium,

AND contact with very hot

parts inexhaust exchanger.

ROHM &

HAASRD 25

Anticorrosion, film

generator, without antifreeze,

to be diluted @ 6-8%

Needs to be tested in

accordancewith Cummins

agreed procedures.

REGULAR

INHIBITOR

A2

Hot water circuits

WITHOUT contact with

very hot parts inexhaust

exchanger, WITHOUT

contact with engine parts

OthersAnticorrosion for circuits without aluminium, suitable for hot

water in closed heating circuits.

HEATING CIRCUITS

INHIBITOR

A3

Hot water circuits entirely

steel & bronze made,

WITH contact with very hot

parts inexhaust exchanger,


solders, aluminium and

copper alloys

Others

Anticorrosion , trisodic phosphate or morpholin, nitrites,

borates, benzoates, or chromates based ,or floating anode

principle, suitable for hot water in steel circuits. PH from

8.5 to 9.5

HIGH-GRADE CHP

COOLANT

ANTIFREEZE

B1

Engine circuits with copper ,

brass, tin solder, aluminium,

AND contact with very hot

parts inexhaust exchanger.

ELF

Coolelf CHP

supra

protection minus 7C, for

hot countries

As above

Coolef supra;

supra GF

protection minus 25C;

minus 35C, ready to use

Glacelf supra

to be diluted with

demineralized water,

protection down to minus

50C

ENGINE COOLANTANTIFREEZE

B2

Engine circuits with copper ,brass, tin solder, aluminium,


very hot parts inexhaust

exchanger.

ROHM &

HAAS

Diagel-6Nto be diluted with

demineralized water,

protection minus 35C

As above

Diamigel-6N protection minus 35C,ready to use

Triagel-6Nprotection minus 20C,

ready to use

SHELLGlycol Shell

type D

protection minus 25C,

ready to use

REGULAR COOLANT

ANTIFREEZE

B3

Hot water circuits


very hot parts in exhaust

exchanger, WITHOUT

contact with engine parts

OthersAutomotive or industrial glycol based coolant. Should

conform to ASTM D 3306, SAE J 1034, BS 6580, BS

5117, or NFR 15-601


22/72




Key considerations for determining the suitability

of other products

The grade 2 and 3 products may be available locally. Gen-

erally, engine antifreeze solutions are formulated with anti-corrosion, anti-cavitation and anti-furring additives.

Antifreeze composition

Monoethylene-Glycol antifreeze (MEG) is suitable for

countries where lower temperatures are minus 35C; For

arctic conditions, monopropylene-glycol (MPG) use is nec-

essary to obtain protection down to minus 47C. (Consult

the factory for these particular conditions).

Never use Methyl Alcohol-based, nor Methoxy propanol-

based antifreeze in coolant circuits. These products will

damage hoses, synthetic rubbers and fluoroelastomer seals.

Never mix different antifreezes in the same water circuit,since a concentration check is not possible by specific

weight measurement.

Never use automotive prepared coolants in engines, since

they are made of poor quality antifreezes, recycled from

industrial processes and containe impurities, various metals

and toxics. They decompose in elevated temperatures, and

corrosion evaluation by spectrography is affected by metal

content.

Organic polymers based inhibitors (suitable)

This new generation of protection products are made of

protective film generators, based on an organic chemical.They are biodegradable and environmentally friendly. They

are active in the presence of aluminium and high wall

temperatures. They are free of amines, phosphates, nitrite

and borates. The B1 category product uses this kind of

advanced product.

Molybdates - phosphates based inhibitors (suitable)

These products are suitable for engines circuits because they

offer a good protection for multiple metals, including

aluminium . Generally, they also contain an organic polymer

which forms a protective layer on surfaces. They may not

be suitable for use in exhaust heat exchangers becausesphosphates may precipitate when in contact with high

temperature walls, and their use for this purpose should only

be approved after satisfactory testing.

Nitrites-borates based inhibitors (not recommended)

Nitrite-borate, nitrite-sodium, nitri te-benzoate based

corrosion inhibitors are the older formulas on the market.

Efficiency is poor on aluminium and tin solderings, but

good on other materials. They are unstable and necessi-

tate frequent checks, concentration adjustments and total

renewal.

They have a reduced toxicity and are partially biodegrad-

able. This is an advantage and a disadvantage: anaerobic

bacteria may develop in closed circuits and form concen-

trations of ammonia. Copper alloys and aluminium are

degraded, even if pH is under 9 (Over pH 9, copper

degradation is greater and more rapid). Also, stress

corrosion is possible on expanded tubes, and copper,

bronze, or brass tubesheets. These products are generally

used in automotive applications. If a nitrite based product

is used for long time, it is necessary to clean the cooling

circuit with approved and non-corrosive biocide. Rinsing

of circuit and coolant preparation shall be performed using

demineralized or bacteria-free water.

Chromates (use forbidden : toxic)

Chromate based products are very efficient but are highly

toxic and, currently, their use is forbidden in Europe and

U.S.

Silicates : (forbidden in engine)

Never use silicate based inhibitors in engine circuits :

coolant velocity is too high (corrosion appears when

velocity is over 2 m/s).

Particular recommendations for ecology

Water treatments are chemicals which may cause pollu-

tions, or may contain non-degradable substances, such as

glycol based formulas.

Coolants containing antifreeze should be disposed of in

a controlled manner. Operatives should wear the correct

protective equipment when handling, even if product isnot toxic.


23/72




6 Boiler Water Treatment

Evaporation of water in boilers leads to the formation of

scale and corrosion. The scale forms an insulating layerwhich reduces the heat transfer rate, so reducing efficiency.

Also more importantly the scale raises the metal temperature,

reducing its strength, which may lead to distortion and

failure.

Water can become acidic due to the presence of dissolved

gases such as oxygen and carbon dioxide, or dissolved

metallic salts such as magnesium chloride, and water in an

acidic condition provides the electrolyte for corrosion to

take place.

Steam boiler water treatment is specially adapted for boilers,

using strong bases which increase the pH to 10-12 to preventthe corrosion which occurs in acid middle. This treated water

is not suitable for engine cooling and should never be used

in engine water circuits.

Properties of water

Some properties of water are :-

pH is the acidity index of water.

7 is neutral, 2 is very acid, 12 is

very alkaline.

Alkaline Hardness - (temporary

hardness) - due to bi-carbonates

of calcium and magnesium

which breakdown to form carbon

dioxide and carbonates which

deposit as soft scale and sludge.

Non Alka li ne Hardne ss -

(permanent hardness) - due to

sulphates and chlorides of

calcium and magnesium.

Total Dissolved solids - all the

substances, harmful or otherwise

dissolved in the water.

Boiler Operation

A power steam boiler is a steam

generator. Steam passes from the

boiler into the circuit, and returns

at low pressure, or condensed.

Some processes do not return

condensate to the boiler, so losses

occur. In this case the steam

boiler water circuit needs to be

replenished with new water,

normally referred to as make up.

Steam boiler water shall be treated to prevent:

- scale and sludge formation,

- corrosion of metals,

- priming ( water particles swept along by steam flow)

Boiler Water Treatment

Due to the wide range of water compositions the following

information is given as an indication only. Each system will

need a specific treatment regime which will ensure correct

operation of the plant.

Steam boiler water composition

Some indications of steam boiler water composition are

depicted in the table below. Generally, feed water is first

demineralized, then treated with an additive, to raise the pH.

Then an oxygen scavenger is added as the water enters the

boiler.

Characteristics of water inthe fire tubes boiler

acceptancecriteria

boiler operating pressure

up to 15 barfrom 16 to 30

bar

PH @ 25Cbetweenindicated

limits11 to 12 11 to 11.7

ALK infrench degrees(ppm as Ca CO

3)

minimum25 f

(250 ppm)25 f

(250 ppm)

maximum140f

(1400 ppm)

120f

(1200 ppm)

NA3

PO4

content minimum 50 to 80 mg/l 100mg/l

SiO2content in ppm maximum 200 mg/l 150 mg/l

ratio SiO2

mg/l on ALK F maximum 1.5 1.5

NaOH free maxi just for PH adjustment, if any

Total dissolved saltsamount

maxi 8g/l


24/72




High-grade integral treatment (C1 category)

Treatment manufacturers propose liquid concentrate forwater treatment which can be injected into the feed water by

means of a dosing pump. In addition, the introduction of

dispersants and protective film additives ensures cleanliness

of internal surface and prevents blockage. They can be used

with partially demineralized water or drinking water with a

total hardness lower than 5f (50ppm as Ca CO3).

Traditional treatment (C2 category)

This treatment is made from basic chemicals which are mixed

in various proportions to reach equilibrium between

alkalinity, antioxygen content, and losses due to blow-

down. This kind of treatment is more complicated, and

needs operator know-how. It is mainly applied to steam

processes without condensate return. Basic treatment of

boiler water is made through the addition of trisodic

phosphate (Na3PO

4) to increase pH of boiler and precipitate

calcium, and catalysated soda sulphite (Na2SO

37 H

2O) to

remove dissolved oxygen.

We do not recommend the use of Hydrazine N2

H4

as an

antioxygent as it is toxic.

If more economical powdered products are to be used, it

is necessary to install a mixing tank for powder mixing

and a means of weighing for dosage.

Product

categoryworking conditions

Recommended brandssubstitution products

Producer Tradename Type of product

BOILER INTEGRAL

C1

Boiler with carbon steel,

inox, copper , bronze,and feeding water circuits

ROHM &

HAASB 108

Anticorrosion, antioxygen,

anti carbon dioxide,

passivant film generator, to

be diluted @1.5 per

thousand

Needs to be agreed by

boiler manufacturer if

stainless steel is used in

structural parts.

DEGREMONTErpacalor

339 +

Erpamine 5

sulfite, phosphates,

dispersent, alkanilizent +

anti-CO2

BOILER

TRADITIONAL

C2

Boiler with carbon steel,

inox,copper , bronze, and

feeding water circuits

CHEMICALS DEALER

Trisodic phosphate

(alcalinizent anti-furring),

sodium sulfite (antioxygen)

and specific amine (anti-

CO2)

Criteria for water analysis and usual abbreviations

FRENCH NAME AB. ENGLISH NAME AB. GERMAN NAME AB.

Potentiel en hydrogne PH acidity PH PH

Duret totale ( titre hydrotimtrique) TH Total hardness TH Gesamthrte G.H.

Duret temporaire _ Temporary hardness _ Karbonathrte K.H.

Duret permanente P Permanent Hardness _ Nichtkarbonathrte N.H.K.

Titre alcalimtrique TA Caustic alkalinity C.A. p-W ert p

Titre alcalimtrique complet TAC Total alkalinity ALK Alkalitt ( m- wert) m


25/72




7 Alternator

General

The alternator is an air-cooled synchronous machine, with

a brushless excitation system, and can be supplied in a

range of output voltages. For voltages that are not in the

standard range, transformers etc are available.

Construction form is IM 2001, i.e., built with two feet and

one flange for fixing on engine end. Shaft end is cylindrical

and keyed.

For the QSV 81-91G generator sets we use 4 pole for 50

Hz 1500 rpm and 60 Hz 1800 rpm and 6 poles for 60 Hz

1200 rpm.

Salient pole PMG alternator

Winding and Electrical Performance

The stator winding in conjunction with carefully selected

pole and tooth designs ensures optimum performance and

low waveform distortion. A fully interconnected damper

winding stabilises the rotor during load changes. Generators

will sustain a maximum short circuit of around 250%

(50Hz), 300% (60Hz), rated current under a three phase L-

L-L short circuit condition. The AVR will support this

condition for eight seconds, at which point the AVRprotection system will de-excite the machine. Current levels

under 2 Phase L-L or 1 Phase L-N short circuit conditions

are much higher than the above L-L-L levels, and must be

removed from the generator by breakers within typically 5

seconds and 2 seconds respectively. The actual values are

indicated in the generator data sheet.

Radio Interference

The absence of brushgear and the high quality AVR ensure

low levels of interference with radio transmissions. Addi-

tional RFI suppression may be supplied if required.

Telephone Interference

THF (as defined by B54999 Part 40) is better than 2%. TIF

(as defined by ASA C50.12) is better than 50.

Waveform Distortion

Total harmonic distortion (THD) of the open circuit voltage

waveform is in the order of 1.5%. Under 3 phase balanced,linear, load conditions the THD is in the order of 3.5%.

Generator design

Enclosure IP23 (NEMA1) is standard for all industrial

alternators. The frame is made of welded steel, optimizing

strength and power to weight ratio. Stator laminations are

made of high quality Silicon electrical steel. Salient poles

rotor is designed to withstand 150% of rated overspeed. Two

bearing constructions (IM 20001) are available with SAE

00 adaptors. Alternators incorporate long life regreasable

bearings. The cooling fan is cast aluminium. End brackets

are made of welded plates with cast iron bearing housings,

seals, and exciter stator support parts. On the drive end a

cast voluted housing is used.

Terminal Boxes

Instrument and control connections are in segregated

compartments, with external access for safety.

Vibration Limits

All alternator rotors are dynamically balanced to better than

BS6861: Part 1 Grade 2.5 for minimum vibration in

operation. Two bearing alternators are balanced with a half

key.


26/72




Insulation/Impregnation of windings

Standard insulation classes for the alternators are class Hfor low voltage (400 - 480V), and F for medium & high

voltage (4160 - 13800 V) .Please refer to data sheet for actual

specifications.

All wound components are impregnated with materials and

processes designed specifically to provide protection against

the harsh environments encountered in generator applica-

tions. Resins are selected and developed to provide the high

build required for static windings and the high mechanical

strength required for rotating components.

A Hybrid System using the best features of Global VPI, and

Resin Rich Technology is used, optimising insulation life inthe slot section, with the advantages of VPI epoxy in the

outhangs for strength, electrical properties and optimum pro-

tection. 5kV machines and above, have Corona Protection

tapes applied.

PMG excitation

A Permanent Magnet Generator (PMG) excitation system is

a standard feature designed to enhance reliability, response

and stability. The PMG provides power via the AVR to the

main exciter, giving a source of constant excitation power

independent of generator output. The exciter output is then

fed to the main rotor through a full wave bridge rectifier,protected by a surge suppressor. The AVR has in-built pro-

tection against sustained over-excitation caused by internal

or external faults. This de-excites the alternator after a preset

period. Over voltage protection is built-in and short circuit

current level adjustment is an optional facility.

Voltage Regulator

(built-in version)

The 3 phase RMS voltage sensing AVR provides very

accurate vc!tage regulation, from no load to full load in-

cluding cold to hot variations for any power factor between

0.8 lagging and unity allowing for 4% engine speed varia-

tions. It is particularly suitable for non linear load

applications.

Three Phase Sensing

Three phase sensing centres any voltage imbalance caused

by load imbalance around the nominal voltage and helps

to ensure trouble-free operation under the most demand-

ing loads.

Parallel Operation

All alternators are well-suited for parallel operation

(optional droop kit fitted) with the mains utility or with

other generators. A fully interconnected damper winding

reduces oscillations around the synchronisation point

during paralleling.

Advanced regulation features

PMG alternators may be operated directly with the

PowerCommand system which includes its own volt-age regulator. See enclosed PowerCommand descrip-

tion for more information.


27/72




Waveform

Low voltage alternators for stationary applications, have

a 2/3 pitch winding as standard, designed in order that

the voltage waveform between phase and neutral at no

load has no third harmonics.

Radio Interference

Radio interference (RFI) is guaranteed to be within the

limits defined in the international standard CISPR.

Overload Capacity

The stator winding withstands high overloads for short

durations, e.g. the continuous shortcircuit current can be

over 3 times the rated current for approx. 10 seconds.

The stator winding supports also withstand the stresses

caused by the maximum asymmetrical short-circuit cur-

rent.

Unbalanced Load

The AC generators can operate on an asymmetric net-

work provided that none of the phase currents exceed

the rated current with an unbalanced current of 30 %.

Stator

The frames are made of welded steel and are heavily ribbed

to prevent deformations. The upper part supports the main

terminal box. The magnetic circuit consists of low-loss

silicon magnetic laminations, securely wedged to the

frames ribs.

Rotor

This consists of a shaft, main rotating exciter winding, a

fan, a balancing disc, an exciter armature and a rotating

rectifier bridge. The shaft is made of carbon steel, forged

or laminated according to its size.

The rotor is of salient pole design manufactured with low

magnetic loss laminations. The exciter coils are maintained

in position by full length heat shrink wedges which serve

for thermal diffusion as well as opposing centrifugal forces.

The fan and the balancing flywheel are keyed on the shaft.

Dynamic balancing of the complete rotor and shaft is car-

ried out on all alternators.Bearings

Roller bearings are rigidly fixed to the stator end plate.

Lubrication is performed by means of grease, with a used

grease escape valve. New grease is inserted during operation

causing the old grease to be evacuated.

Fan Cooling

The air inlet is located at the rear of the alternator and the air

outlet at the driving end ; air escapes through the gap by

means of the fan keyed on the shaft. If the alternator is to

operate in a dusty environment, then filter elements can be

fitted. Consult the Gas Projects team at Cummins UK,Manston Office for details as the alternator output will

reduce.

Stator winding

Low voltage coils are wound with round enameled wires.

Impregnation is done with polyester based varnish impreg-

nated under vacuum. Medium voltage coils are built with

fiberglass-lapped flattened enameled wires, the sections are

isolated using mica products. Special precautions are

taken to ensure perfect wedging of the sections and

connections using insulating rings and inserts. Global

impregnation with solventless polyester resin under vacuum

and pressure provides the unit with a remarkable mechani-cal strength, a very high degree of insulation impervious to

humidity, oil, fuel-oil, diesel fumes and industrial chemicals.

Standard insulation classes for the alternators are class H

for low voltage (400 - 480 V), and F for medium & high

voltage (4.160 - 13.800 V).


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Rotor winding

The Rotor is built with rectangular copper enameled bars or

insulated with two fiberglass layers and totally impregnated

with solventless polyester resin under vacuum and pressure.

Terminal box - Connection

A large-sized and easily accessible terminal box is located

at the alternator top. Inside, the six windings ends are wired

to connecting bars (for low voltage) or to insulators (for

medium and high voltage), thus allowing easy connection.

Thermal protection

PT 100 thermal sensors (100 ohms at 0C) are enclosed in

the stator winding and implanted in the bearings. Output

may be used either for temperature measurement or alarm

and tripping.

Brushless excitation

Field flashing is ensured by residual magnetism, deliveringminimal field to enable voltage regulator operation. Exci-

tation alternating current is drawn off an inverted alternator

keyed onto the rotor shaft. Inverted means that the armature

is rotating, and field poles are fixed. The excitation current

is rectified through a Graetz bridge of silicon diodes properly

sized and protected by resistors connected in parallel on the

alternator rotor windings. The rectifier is fixed onto the

alternator rotor, and so named rotating rectifier. If out of

control, the exciting system trends to minimal voltage output.

Shunt regulator

The regulator (6) is supplied by the generator output (1) and

controls the excitation in the exciter field (5). The excitationcurrent from the exciter armature (4) is rectified by the rec-

tifier bridge (3) and supplies the alternator pole wheel (2). A

three phase current booster is supplied, and a current trans-

former (dotted line on diagram) is allowed for parallel op-

eration reactive power control. A potentiometer allows

adjustment of the nominal voltage over a 5 % range.

Voltage regulator functions

The function of the basic AVR is to keep the terminal voltage

of the alternator constant at set point under various load

conditions, when operating on isolated bus. AVR controls

also the paralleled operation with other units in a power gen-

eration system, and with an infinite grid. To make parallel-ing possible, the AVR is equipped with a voltage droop cir-

cuit, which is enabled as soon as the generator is paralleled

on live bus. When increasing reactive load, the terminal volt-

age decreases according to a predetermined characteristic.

This reactive load sharing is important to prevent an imbal-

ance and circulating currents in the system.

Basic function : the regulator allows operation of a single AC

generator by itself or parallel-coupled to AC generators of

comparable power. A current transformer allows appropriate

sharing of the reactive power.

2nd function : the second function also allows parallel op-

eration with a much more powerful network with regula-

tion of the AC generator power factor.

3rd function : the third function also offers voltage pre-equalization between the AC generator and the network

before coupling.

The rotor poles include a damper winding to assist in

parallel operation.

Regulation basic performances

Following performances are typical and cannot con-

stitute a contractual guarantee.

Under steady conditions, the voltage is kept constant

within 1% between 0 and 4/4 load, P.F 0.6 to 1 induc-

tive, in cold or hot state, at rated speed within 5%.

Output voltage is remotely adjustable by +/-5%.

Under transient conditions, the alternator is able to return

to nominal voltage under 0.5s. Please contact sales sup-

port for calculation of performance in regard with step

reloading nature.

Short-circuit current

Compounding is designed so as to sustain a three-phase

or single-phase current equal to 2 to 5 time rated current

for a few seconds in the event of short-circuit, enabling

proper operation of protections and ensuring selectivity

in distribution systems.

Generator protection

Generator protections for isolated and paralleled opera-

tion are provided. Optional protections are to be defined

according to bus specificities or local regulation. Power

distribution system protections are defined by others, but

they shall be communicated to project staff to check the

effective selectivity in the whole system.


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8 Genset Control Panel

(GCP)

Genset control

The genset control is microprocessor based and includes

features for engine control, as well as generator and power

plant interfacing controls.

Gas engine control

The CENSE control acquires data from analogue and logic

sensors installed on the engine. Some of these parameters

are for alarm and display purposes, others are for cylin-

der ignition tuning. CENSE data is sent to the MCM 700

for engine control.

The Master Control Module MCM 700 receives (from

Power Command Supervisor (PCS)) a power demand to

set the active power of genset, and real time data from

CENSE. The signals for start, stop and torque demand

are transmitted to SSM558 and CCD/PDM

The Capacitive Coil Driver (CCD) receives ignition data

from the MCM, and interprets it to output cylinder indi-

vidual voltage, containing one or multiple firing signals

per ignition event, to each coil. It receives the feedbacksensor signal from each coil and then adjusts energy

delivery for each spark.

The prognostic Diagnostic Module (PDM) outputs diag-

nostics of the spark plug and coil for each cylinder, and

prognost ic s for tr endi ng the condit ion of these

components. It also outputs faults of the coil section.

SSM 558 is a governing system for controlling the air-

gas mixture. The gas rate is set by an electrically operated

valve, controlled by the SSM 558, from the gas flow

required. Valve position is determined from feedback. The

engine governing system is controlled either by Woodward723A or MCM 700 governing systems. The actuator is a

PROACT III series.

Generator control

The standard PMG generator is controlled by the PCS

device, and the shunt-booster generator is controlled by

the autonomous Automatic Voltage Regulator (AVR) re-

ceiving feedback from built-in PTs and CTs. The GCP

includes digital annunciator and parameters display, a pro-

grammable Logic Controller (PLC), genset protection de-

vices, start, stop and paralleling controls.


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Genset Control Panel specification

The QSV G.C.P. is a micro-processor based system designed

to interface directly with the engine or the monitoring

components. The control panel provides extensive integrated

system monitoring and control functions using the very re-liable Power Command Supervisor TM. It further utilises a

PLC to generate a range of communication protocols for

both internal and external usage.

GCP System Configuration

The Genset Control Panel can be located either locally at

the genset or remotely, up to a distance of 100 metres, ie; in

a control room environment.

Standard components used to provide the system control

comprise :Control batteries and charger ,

PC based HMI (touchscreen) ,

PLC based auxiliary control ,

PLC based CENSE interface ,

PowerCommand Supervisor,

Aux AC enclosure (genset mounted) ,

Engine interface enclosure (genset mounted) .

The system is intended for use in single or multi-set iso-

lated bus or single set base load utility paralleling applica-tions whilst providing both isolated bus paralleling control

(set to set synchronising, isochronous KW and KVAR load

sharing) and base load utility paralleling (synchronising to

utility, base load KW control, VAR/PF control). It provides

compatibility with master controllers for multi set utility

paralleling applications requiring supervisory system con-

trol, ie, load demand, multi level load shed/add etc, whilst

enabling data control and monitoring via an optional

(Modbus) communications interface.

Control Panel Environmental HardeningThe control system touchscreen, PCS and other optional door

mounted equipment are provided with sealed front faces to

minimise the effects of dust and moisture on the equipment.

Operating range of the complete GCP is :

Operating Temperature : 0 to +50 C

Rating : IP54

Construction

The control system is housed in a rigid, free standing,

metal enclosure designed to require front access only.

PC Based H.M.I. (Touchscreen)

The HMI is the Human Machine Interface. A micro-

processor based graphic interface (touchscreen) package

is provided to allow operator monitoring and control. Data

from the genset is displayed to the operator in layered

menus so that it is easy to understand and allows opera-

tors to easily learn the functionality and diagnostic facili-

ties of the unit

The touchscreen provides data and graphics on an EL

monochrome display. The microprocessor is80486SXLC2-50 technology and includes a DOS based

operating system and Interact application software. It

is complete with a real time clock, (month/day/year/hour/

min/sec) with separate battery backup and holds an

extensive 5MB of FlashDisk memory.

The screen is mounted on a console on the front of the

GCP with gaskets between the touchscreen and the

enclosure for environmental protection. The HMI is

interconnected to the PLC via serial comms utilising a

Modbus protocol.

PC Based HMI (Touchscreen) Specifica-

tion

Processor : 80486SXLC2-50, 8MB DRAM, 256 kB static

RAM, 5 MB FlashDisk, 4 serial and 1 parallel interface

(LPT1), CAN Bus interface, 2 PCMCIA type II slots.

Screen Type : Amber electroluminescent (EL) flat panel.

The screen surface is hard coated, durable and anti-glare

to allow ease of use in any lighting condition and long

life. A screen save facility is provided to enhance life and

save power.

Screen Size : 10.4 (264mm) diagonal with 640 x 480

pixel resolution.

Operating System : DOS 6.22.

Application Software : InteractTM Runtime System III.

PLC Interface : Serial Communication port slot with

Modbus Protocol.

Protection : Nema 4.


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PowerCommand Supervisor

This unit is a microprocessor based genset monitoring,

metering and control system. It is integrated into the GCP

and incorporates the following key features;

Voltage Regulator

Synchronizer (Freq, Phase & Volts)

Iso-Bus kW and kVAR load sharing

Utility Paralleling kW Load Control

Utility Paralleling pF Control

AmpSentryTM Alternator Protection

Overload,

Overcurrent [51], Short circuit [50],

High AC Volts [59],

Low AC Volts [27],

Underfrequency [81u],

Sync Check, Fail to Sync,

CB Fail to Close,

Reverse Power [32],

Loss of Excitation [40],

Phase Rotation

Alternator Metering

Enclosure Environmental Hardening

The front panel of the unit is formed by a single mem-

brane that covers the entire surface. The facia is easy to

clean and impervious to water spray, dust and oil/exhaust

residue. Switches for control are incorporated into the door

which is gasketted with a dual moisture and RFI/EMI

gasket to protect internal components from airbourne

contaminants.

Temperature Rating : -5C to + 55C.

External Optional Connectivity : VGA monitor, disk

drive, mouse interface, IBM AT keyboard port.

Main Screen

The main screen is designed to enable the operator to

determine the current genset status. It further allows access

to the data embedded in the layered screens. Data Includes

: Voltage per phase, Current per phase, Current per phase,

kW, MW/hr, Frequency, Power factor, Oil pressure, Speed

and Engine hours.

Touchscreen activities allow the following access:

Engine Data,

Alternator Data,

AC Auxiliaries mimic,

Alarm Activities,

GCP User Level Configuration,

Related Plant Data

The main screen is designed to include an alarm capabil-

ity so that the operator is immediately advised of all alarm

and shutdown conditions.

Alternator Statistics

This screen enables the operator to analyse the alternator

data in more detail. Data includes :

AC Voltage Phase - Phase,

AC Voltage Phase - Neutral,

AC C

173-Gas Substations Project Guide

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