generator construction(rev2)

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Generator Generator Construction Construction By By Ms. Soh Ley Bau Ms. Soh Ley Bau Generation Section--Electrical Generation Section--Electrical Unit (ILSAS),TNB Unit (ILSAS),TNB

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Page 1: Generator Construction(Rev2)

Generator Generator ConstructionConstruction

ByBy Ms. Soh Ley BauMs. Soh Ley Bau

Generation Section--Electrical Unit Generation Section--Electrical Unit (ILSAS),TNB(ILSAS),TNB

Page 2: Generator Construction(Rev2)

System OverviewSystem OverviewPrinciple of Thermal Power Plant

Page 3: Generator Construction(Rev2)

System OverviewSystem Overview Principle of Thermal Power PlantPrinciple of Thermal Power Plant

Page 4: Generator Construction(Rev2)

System OverviewSystem Overview

Furnace The chemical energy from fuel is converted to

heat

Back

Page 5: Generator Construction(Rev2)

System Overview System Overview

The heat from the burning fuel causes The heat from the burning fuel causes water in the boiler change to steamwater in the boiler change to steam

Boiler

Back

Page 6: Generator Construction(Rev2)

System OverviewSystem Overview

The steam is sent to the turbine, where it causes the turbine blades to

rotate. The turbine converts the energy

in the steam into mechanical energy.

Steam Turbine

Back

Page 7: Generator Construction(Rev2)

System OverviewSystem Overview

Generator

The turbine shaft connects the turbine to the generator through a coupling and as the turbine rotates,

the generator rotor shaft also rotates.

NextCoupling?Coupling?

Ask meAsk me

Page 8: Generator Construction(Rev2)

System OverviewSystem Overview

GeneratorThen, the generator converts the

mechanical(rotating) energy into electrical energy

NEXT-DEMO

Page 9: Generator Construction(Rev2)

Turbine

Coupling

System OverviewSystem Overview

Generator

Side Turbine side

I get it !!

Page 10: Generator Construction(Rev2)

How the electrical generator How the electrical generator work?work?

Page 11: Generator Construction(Rev2)

How AC How AC generator generator

work?work?

Page 12: Generator Construction(Rev2)

AC AC GeneratorGenerator

Page 13: Generator Construction(Rev2)

Prepared by @ Ms.Soh Ley Bau 13

Single Phase Generator/ Single Phase Generator/ AlternatorAlternator

Page 14: Generator Construction(Rev2)

Types of GeneratorsTypes of Generators

Turbo Generator (Turbo Generator (Cylindrical Cylindrical Rotors)Rotors)

Turbine GeneratorTurbine Generator

Salient pole GeneratorSalient pole GeneratorHydro GeneratorHydro GeneratorDiesel GeneratorDiesel Generator

Page 15: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole Generator

Page 16: Generator Construction(Rev2)

Salient Pole Generator Salient Pole Generator Hydroelectric PlantHydroelectric Plant

(Chenderoh, Sg Perak)(Chenderoh, Sg Perak)

Page 17: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole GeneratorStator WindingsStator Windings~ Cameron Highland~ Cameron Highland

Page 18: Generator Construction(Rev2)

Salient Pole Rotor Salient Pole Rotor

A 4 Pole rotor starts as a solid rough forging

The shaft, spider and the 4 poles and pole tips are created by machining away part of the forging.

The strip wound fielding winding is added to complete the rotor

Page 19: Generator Construction(Rev2)

Solid 6 pole machine with Solid 6 pole machine with brushless exciterbrushless exciter

Page 20: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole GeneratorRotor Pole Rotating Type Exciter

Page 21: Generator Construction(Rev2)

Salient Pole RotorSalient Pole RotorCameron Highland Cameron Highland

Page 22: Generator Construction(Rev2)

Salient Pole Rotor Salient Pole Rotor Kenyir (112MVA, 24 poles)Kenyir (112MVA, 24 poles)

Page 23: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole GeneratorDiesel Generator

Page 24: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole Generator6.6kV Black Start Diesel Generator (PD1)

Page 25: Generator Construction(Rev2)

Salient Pole GeneratorSalient Pole GeneratorDiesel Generator,12 poles Diesel Generator,12 poles

Page 26: Generator Construction(Rev2)

WWhat are the hat are the

functions of functions of generator in generator in the Power the Power

Utility Utility Industry?Industry?

Page 27: Generator Construction(Rev2)

IntroductionIntroduction To convert the rotational To convert the rotational

mechanical energy (steam mechanical energy (steam turbine) into electrical energyturbine) into electrical energy

Steam Steam TurbineTurbine

GeneratorGeneratorMain Main exciterexciter

Page 28: Generator Construction(Rev2)

IntroductionIntroduction

To supply energy to the power To supply energy to the power grid and route some power to grid and route some power to

machine auxiliaries (via the machine auxiliaries (via the Unit Transformer)Unit Transformer)

Page 29: Generator Construction(Rev2)

One-line diagram for generator and One-line diagram for generator and generator transformergenerator transformer

Page 30: Generator Construction(Rev2)

Layout of Power PlantLayout of Power Plant

Page 31: Generator Construction(Rev2)
Page 32: Generator Construction(Rev2)
Page 33: Generator Construction(Rev2)

Pressure Rise in a TransformerPressure Rise in a Transformer

Page 34: Generator Construction(Rev2)
Page 35: Generator Construction(Rev2)

Transformer-Phase to Earth Transformer-Phase to Earth FaultFault

Page 36: Generator Construction(Rev2)

Transformer-Phase to Earth Transformer-Phase to Earth FaultFault

Page 37: Generator Construction(Rev2)

Transformer-Phase to Earth Transformer-Phase to Earth FaultFault

Page 38: Generator Construction(Rev2)

Split Generator ShaftSplit Generator Shaft

Page 39: Generator Construction(Rev2)

Generator Main Circuit Generator Main Circuit Breaker (SFBreaker (SF66))

Page 40: Generator Construction(Rev2)

Generator Main Circuit Generator Main Circuit Breaker (SFBreaker (SF66))

Page 41: Generator Construction(Rev2)

Components of GMCBComponents of GMCB

Page 42: Generator Construction(Rev2)

Generator ConstructionGenerator Construction

Stator

Rotor

Bracket

Page 43: Generator Construction(Rev2)

Generator ConstructionGenerator ConstructionMain Components:

– a.)Stator (stationary part)– b.)Rotor (rotating part)– c.)Rotor Bearing– d.)Pilot AC Exciter– e.)Main Exciter– f.)Automatic Voltage Regulator (AVR)– g.) Rotating rectifier– h.)Stator Output Leads and Isolated Phase Bus– i.)Generator Neutral Earthing– j.)Hydrogen Cooling system

Page 44: Generator Construction(Rev2)

StatorStatorStator consists of stator core,stator frame,

slot wedges and etc.Function:-Armature- produce output of the generator

Page 45: Generator Construction(Rev2)

Stator ConstructionStator Construction

-Special explosion proof design- In case any gas explosion inside, it provides a safe tight housing

-MaterialMaterial :No.1 SM41 AP, of JIS G 3106 Rolled Steel for welded Construction and is tested to be free from cracks etc. by a supersonic test

•Stator Frame

Page 46: Generator Construction(Rev2)

Stator ConstructionStator Construction

Stator Stator corecore

WedgeWedge

End winding

Page 47: Generator Construction(Rev2)
Page 48: Generator Construction(Rev2)

Stator ConstructionStator ConstructionStator Core

The functions of stator core are :

a) Concentrate the lines of magnetic flux around the stator windings

b) Support and hold the windings in position around the rotor as the rotor turns.

Page 49: Generator Construction(Rev2)

Stator coreStator core

Figure : Side view of the stator core

*Note : Air-cooled generator in Serdang power station

Page 50: Generator Construction(Rev2)

Stator ConstructionStator Construction Slot Wedge

Function:

The stator windings or stator coils are simply long insulated bars which are assembled and wedged-locked into the stator core slots running length wise through the generator.

Page 51: Generator Construction(Rev2)

Stator ConstructionStator Construction Slot Wedge

Wedge is located on the top of each slot

End winding

Page 52: Generator Construction(Rev2)
Page 53: Generator Construction(Rev2)

Stator ConstructionStator ConstructionStator Lamination

-To form a stator core, high quality silicon steel plates of little core loss are used and punch them with a die in such segments as shown in the illustration.

-After giving them varnish treatment, pile them up on a stator frame.

Page 54: Generator Construction(Rev2)
Page 55: Generator Construction(Rev2)

Stator LaminationStator Lamination

*Stator Core

Page 56: Generator Construction(Rev2)

Stator LaminationStator Lamination

Page 57: Generator Construction(Rev2)
Page 58: Generator Construction(Rev2)

Stator ConstructionStator ConstructionStator core end

Page 59: Generator Construction(Rev2)

Stator ConstructionStator Construction Stator core end Functions: -The coil end is rigidly tied with a glass cord to the micarta

coil support which is bolted to the stator core and laminated core.

(Reason: withstand the immense power at the time of short circuit )

-At the extreme end is placed a resin ring made of epoxy impregnated glass fiber, and molding mixtures are stuffed in the space between the said ring and coil in order to support them.

Page 60: Generator Construction(Rev2)

Effect of the Flexible MountingEffect of the Flexible Mounting

Page 61: Generator Construction(Rev2)

Flexible MountingFlexible Mounting

~ To prevent high level vibration (two-pole machines) from being transmitted to the frame and foundation, the stator core is supported from the frame by a flexible mounting.

~ To support the weight of the core and to withstand short circuit torque.

Page 62: Generator Construction(Rev2)

Flexible MountingFlexible Mounting

Page 63: Generator Construction(Rev2)

Rotor ConstructionRotor Construction

Page 64: Generator Construction(Rev2)

Rotor shaft of an inner cooled Rotor shaft of an inner cooled generatorgenerator

Pole face

Page 65: Generator Construction(Rev2)

Prepared by @ Ms.Soh Ley Bau 65

Rotor ForgingRotor Forging

@soh-Serdang GT5

Page 66: Generator Construction(Rev2)

Rotor ConstructionRotor ConstructionRotor coil

Page 67: Generator Construction(Rev2)

Example of rotor end windingExample of rotor end winding*Serdang Power Station Nov.2003,Unit 2

Page 68: Generator Construction(Rev2)

Rotor ConstructionRotor ConstructionRotor CoilMaterial : cold worked silver bearing

copper

Function: Field coil of the generator

Page 69: Generator Construction(Rev2)

Rotor ConstructionRotor Construction

Coupling at turbine side

Rotor

@Unit 1 SJSSAA,kapar(Oct 03)

Page 70: Generator Construction(Rev2)

Rotor ConstructionRotor Construction

Retaining ring

@Unit 1 SJSSAA,kapar(Oct 03)

Page 71: Generator Construction(Rev2)

Retaining RingRetaining Ring

Function:

~To support the rotor coil end, thin cylindrical coil retaining rings are force fitted to both ends of the rotor body

@Sohlb Serdang GT5

Page 72: Generator Construction(Rev2)

Rotor ConstructionRotor Construction

End windings of the rotor coil

@Unit 1 SJSSAA,kapar(Oct 03)

Page 73: Generator Construction(Rev2)
Page 74: Generator Construction(Rev2)

Generator PartsGenerator Parts

NEXTNEXT

Page 75: Generator Construction(Rev2)

Generator’s Journal BearingGenerator’s Journal Bearing Bearing # 5 (Turbine side)

Bearing # 6

(Excitation side)

NEXTNEXT

@Unit 1 SJSSAA,kapar(Oct 03)

Page 76: Generator Construction(Rev2)

Generator’s Journal BearingGenerator’s Journal Bearing

Function:To support the generator rotor.

(In order to keep the shaft free from undue stress because of deflection of shaft and misalignment, the bearings are of spherical surface which are machined to have a high pressure oil-line,lubricating oil line, etc.

BACKBACK

Page 77: Generator Construction(Rev2)

Bearing BracketBearing BracketTop half of bearing bracket

Bottom half of bearing bracket

Main Exciter side

Rotating Rectifier

NEXTNEXT

@Unit 1 SJSSAA,kapar(Oct 03)

Page 78: Generator Construction(Rev2)

Bearing BracketBearing Bracket

Dismantle the top half bearing bracket using overhead crane

NEXTNEXT

@Unit 1 SJSSAA,kapar(Oct 03)

Page 79: Generator Construction(Rev2)

Bearing BracketBearing Bracket- Welded construction & is directly fixed to the stator frame

- It is divided into two parts both at the turbine side & the exciter side.

- Having sufficient mechanical strength by means of many ribs.

- In the bracket are included bearings, gland seal ring and oil seal and the lower section of the lower bracket constitutes a deforming tank.

- To fix the stator frame, gasket and sealing compounds are used and the construction is such that gas leakage is kept to the minimum.

BACKBACK

Page 80: Generator Construction(Rev2)

Gland seal Gland seal Gas tight enclosure for hydrogen cooled generator

Function:

-To prevent hydrogen gas leakage along the shaft

NEXTNEXT

@Unit 1 SJSSAA,kapar(Oct 03)

Page 81: Generator Construction(Rev2)

Gland sealGland seal

BACKBACK

Page 82: Generator Construction(Rev2)

Seal ringSeal ring

Position of seal ring

Seal ring (Bottom half)

Gland seal

Page 83: Generator Construction(Rev2)

Seal ringSeal ring

BACKBACK

Page 84: Generator Construction(Rev2)

Air Gap BaffleAir Gap Baffle

Air Gap BaffleAir Gap Baffle

Function:Function:

-To separate the -To separate the high pressure and high pressure and the low pressure the low pressure ventilation zones at ventilation zones at the exciter end of the exciter end of the rotor & stator.the rotor & stator.

BACKBACK

Page 85: Generator Construction(Rev2)

BlowerBlower

- Multi-stage axial blower is installed only at turbine side (inner cooled machine)

Function:

-To feed the cooling gas(cold gas) into a long and narrow vent duct in the axial direction ventilation.

NextNext

Page 86: Generator Construction(Rev2)

BlowerBlowerBlower Blade

Material:

Ni-Cr-Mo steel

Page 87: Generator Construction(Rev2)

Cooling Fan/blowerCooling Fan/blower**Unit 5 Port Dickson Power Station****Unit 5 Port Dickson Power Station**

BACKBACK

Page 88: Generator Construction(Rev2)

Blower ShroudBlower Shroud

BACKBACK

Page 89: Generator Construction(Rev2)

Gas cooler/Hydrogen CoolerGas cooler/Hydrogen Cooler

NEXTNEXT

Page 90: Generator Construction(Rev2)

Gas Cooler Hydrogen CoolerGas Cooler Hydrogen Cooler-Two gas coolers are each arranged vertically both on the right side and the left side of the turbine side in the generator.

-Cooling tubes with spiral copper fins are used as shown (b).

-The cold gas temperature is designed to maintain below 45C when the cooling water temperature is 40 C .

(a)

(b)

NEXT

Page 91: Generator Construction(Rev2)

Gas Cooler Hydrogen CoolerGas Cooler Hydrogen Cooler

1. During generator operation, electrical resistance heating in the gen.windings-creates large amount of heat

2. This heat is removed from gen.windings-circulating hydrogen gas through windings

3. Circulation is accomplished by cooling fan.

4. The heat from hydrogen gas is then removed by cooling water flowing through hydrogen coolers

BACKBACK

Page 92: Generator Construction(Rev2)

Generator Generator Exciter System Exciter System Fundamentals Fundamentals

Page 93: Generator Construction(Rev2)

Excitation SystemExcitation System

Functions a.) Supply, control and regulate the amount of field

current applied to the generator field winding, so that the generator output voltage kept constant, at predetermined levels, under varying load conditions.

b.) Allow the operator to change the reactive loading of the machine

Page 94: Generator Construction(Rev2)

Basic Exciter PrinciplesBasic Exciter Principles

Three factorsThree factors which affect the output of a generator.

1. The number of conductorsnumber of conductors (fixed for a particular generator)

2. The speed of rotation of the rotorspeed of rotation of the rotor( fixed at 3000RPM for 2 pole machines operating on a 50Hz system)

3. The strength or density of the magnetic fluxstrength or density of the magnetic flux or field( varied by increasing or decreasing field current)

Page 95: Generator Construction(Rev2)

Types of ExcitersTypes of Exciters

1. Static Type System1. Static Type System AC power directly from the main generator

leads The power taken from the generator leads

is first stepped down through a special transformer and then fed to rectifiers for conversion to dc.

Page 96: Generator Construction(Rev2)

Types of ExcitersTypes of Exciters

2. A-C Generator (Alternator)/PMG 2. A-C Generator (Alternator)/PMG Excited SystemExcited System

The main generator drives an alternator to produce ac power, which is then converted to dc by means of rectifiers.

Page 97: Generator Construction(Rev2)

Static ExcitationStatic Excitation

Page 98: Generator Construction(Rev2)

Static Excitation Static Excitation

If generator voltage not reaches to 60% within 20 sec, initial excitation failure alarm is raised.

30sec20 sec 0 sec

Page 99: Generator Construction(Rev2)

Excitation TransformerExcitation TransformerDry type Excitation Transformer Dry type Excitation Transformer

( 3.44MVA 15/0.88kV)( 3.44MVA 15/0.88kV)

Page 100: Generator Construction(Rev2)

Core Type TransformerCore Type Transformer

Page 101: Generator Construction(Rev2)

PMG Excited SystemPMG Excited System

PhotoPhoto

AC

Page 102: Generator Construction(Rev2)

Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem

1. Reliability. “ AC Exciter-Rotating Rectifier” mounted on a common shaft

2. Maintenance cost is reduced because there is no brush, commutator and slip ring

3. There is no troubles of insulation resistance since the adhesion of carbon duct is varnish.

4. All devices are placed in closed housing and not exposed to the atmospheric conditions.

Page 103: Generator Construction(Rev2)

Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem

5. Change of brush is needless during operation so that with an increase of safety, the operation can continue for the long term.

6.Generator field breaker,field regulator and exciter bus or cable become unnecessary.

(not required any DC bus duct from excitation transformer to IPB for static excitation)

Page 104: Generator Construction(Rev2)

Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem

7. Foundation cost will also reduces since air ducts and exciter bus (Excitation Transformer) are not needed in foundation.

8. It permits continuous conservative operation and tolerates transitory over loads to ceiling voltages.

9. Spare exciter is also unnecessary

Page 105: Generator Construction(Rev2)

GeneratorGenerator

AVR card

Rotating

Rectifier

PMGPMG

Main generator

NEXTNEXT

Page 106: Generator Construction(Rev2)

Brushless Excitation System-Main ExciterBrushless Excitation System-Main Exciter

PMG Rotating Armature

Rotating Rectifier

BackBack

Page 107: Generator Construction(Rev2)

Brushless Excitation System-PMGBrushless Excitation System-PMG

Rotating armature PMG or Pilot Exciter

NEXTNEXT

Page 108: Generator Construction(Rev2)

Permanent Magnet GeneratorPermanent Magnet Generator

PMG StatorPMG Stator

PMG RotorPMG Rotor

NEXTNEXT

Page 109: Generator Construction(Rev2)

Pilot Exciter/PMG/High Pilot Exciter/PMG/High Frequency GeneratorFrequency Generator

PMG= Permanent Magnet GeneratorFunction: To provide a constant source of excitation power

for exciter field via the Automatic Voltage Regulator(AVR) which is the controlling device governing the level of excitation provided to the exciter field

BackBack

Page 110: Generator Construction(Rev2)

Automatic Voltage regulator Automatic Voltage regulator (AVR) Panel (AVR) Panel

Function:

-AVR responds to a voltage sensing signal derived, via an isolating transformer (Potential Transformer) from the main stator winding.

NEXTNEXT

Page 111: Generator Construction(Rev2)

Automatic Voltage Automatic Voltage Regulator (AVR) PanelRegulator (AVR) PanelFunctions:Control the field current in order to

maintain the generator output voltage at a predetermined level, with minimal changes over a wide range of load demand.

Adjusting the Q(Mvar) reactive power

Page 112: Generator Construction(Rev2)

Automatic Voltage Automatic Voltage Regulator (AVR) PanelRegulator (AVR) Panel

Improve the power system stability (transient stability)

Suppress the over generator voltage on the load rejection

BackBack

Page 113: Generator Construction(Rev2)

Exciter Stator & Exciter RotorExciter Stator & Exciter Rotor

Field coil on the stator of main exciter

(Rotating Armature)

NextNext

Page 114: Generator Construction(Rev2)

Exciter Stator & Exciter RotorExciter Stator & Exciter Rotor

Function:-As an AC Generator (Rotating Armature)-Exciter Stator-Create magnetic field-Exciter Rotor-Induced current

BackBack

Page 115: Generator Construction(Rev2)

Rotating RectifierRotating Rectifier

Function:AC to DC Converter-To provide excitation

(DC supply) into the main rotor

BackBack

Page 116: Generator Construction(Rev2)

?? ????

Page 117: Generator Construction(Rev2)

Excitation with carbon brushExcitation with carbon brushSJTJ,Unit 5~2003SJTJ,Unit 5~2003

Page 118: Generator Construction(Rev2)

Cartridge TypeCartridge TypeSJTJ,PD1 2004SJTJ,PD1 2004

Page 119: Generator Construction(Rev2)

Slip Ring BrushGearSlip Ring BrushGear

Page 120: Generator Construction(Rev2)

Slip RingSlip Ring

Prepared by Ms.Soh

Page 121: Generator Construction(Rev2)

Stator Terminal Box and Stator Terminal Box and BushingBushing

Page 122: Generator Construction(Rev2)

Terminal BoxTerminal Box

Page 123: Generator Construction(Rev2)

Stator TerminalStator Terminal

Bushings

Function:

- To route the electricity produced in the stator windings

Page 124: Generator Construction(Rev2)

Isolated Phase systemIsolated Phase system

Function:

-The output of the stator is connected to the generator transformer via an isolated Phase Bus (IPB) system

Page 125: Generator Construction(Rev2)

Isolated Phase systemIsolated Phase system

•Required high reliability

•Made of high quality materials and welded constructions are adopted.

•Dry air is constantly feed into IPB bus through the air supply equipment

•Prevent external air from flowing into IPB

•Prevent the inside of IPB from dewing

Page 126: Generator Construction(Rev2)

Generator Neutral EarthingGenerator Neutral Earthing

Function:Function:• To limit the stator To limit the stator

earth fault current earth fault current that can flowthat can flow

• (to prevent the earth fault (to prevent the earth fault current flow through the core of current flow through the core of the generator)the generator)

Page 127: Generator Construction(Rev2)

Generator Transformer & Generator Transformer & TransmissionTransmission

Generator Transformer (11kV/275kV)

Transmission side (switchgear) 275kV

Note:*PD power station

Page 128: Generator Construction(Rev2)

Seal Oil SystemSeal Oil System

Page 129: Generator Construction(Rev2)

Seal Oil SystemSeal Oil System

Function:-To lubricate the seals and prevent

hydrogen from escaping from the generator without introducing an excessive amount of air and moisture into the generator

Page 130: Generator Construction(Rev2)

Hydrogen cooling systemHydrogen cooling system(Inner Cooling)(Inner Cooling)

Figure :Longitudinal sectional view of generator

Page 131: Generator Construction(Rev2)

Characteristics of Hydrogen CoolingCharacteristics of Hydrogen Cooling Table 1:

  Air  

Hydrogen

Density 

1.00 0.07

Thermal conductivity 

1.00 7.00

Heat Transfer coefficient from surface gas 

1.00 1.35

Specific heat 1.00 0.98 

Support of combustion Yes 

No

Oxidizing agent 

Yes No

Page 132: Generator Construction(Rev2)

Prepared by @ Ms.Soh Ley Bau 132

Serdang GT5

Siemen

Prepared by Ms. SOh

Prepared by Ms.Soh

Prepared by Ms.Soh

Page 133: Generator Construction(Rev2)

Prepared by @ Ms.Soh Ley Bau 133

Serdang GT5

Siemen

Prepared by Soh

Page 134: Generator Construction(Rev2)

Prepared by @ Ms.Soh Ley Bau 134

Page 135: Generator Construction(Rev2)

Characteristics of Hydrogen CoolingCharacteristics of Hydrogen Cooling

An ideal cooling mediumAn ideal cooling mediumThe combination of low density and high specific heat of hydrogen

Lower effectiveness of air as a cooling mediumLower effectiveness of air as a cooling medium (requires a 20% to 30% size increases over a hydrogen cooled machine a similar rating).

Design for higher electrical loadingDesign for higher electrical loading compared to the air –cooled machine due to better cooling.

Page 136: Generator Construction(Rev2)

Hydrogen Inner-cooling Hydrogen Inner-cooling systemsystem

To remove heat directly from the stator and rotor conductors by hollowing them and flowing a high velocity gas through these hollows

Advantages:– Sharply increase output in similar size– Possible to employ higher hydrogen gas pressures

than a conventional hydrogen cooled unit

Page 137: Generator Construction(Rev2)

AcknowledgementAcknowledgement

Mr. Low Siew Wooi,JPSMr. Low Siew Wooi,JPSMr. Foo Hi Kium, ILSASMr. Foo Hi Kium, ILSASMr. Mok Kin Wah,ILSASMr. Mok Kin Wah,ILSASMr. Lew Kar Wong, SJTJMr. Lew Kar Wong, SJTJMr. Thong Lit Yen, TNBHMr. Thong Lit Yen, TNBH