Generator Construction(Rev2)

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Transcript of Generator Construction(Rev2)

Generator Construction


Ms. Soh Ley Bau

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

System OverviewPrinciple of Thermal Power Plant

System OverviewPrinciple of Thermal Power Plant

System Overview

FurnaceThe chemical energy from fuel is converted to heat


System Overview


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


System Overview Steam TurbineThe 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.


System Overview

Generatorturbine shaft connects the turbine to the generator through a coupling and as the turbine rotates, the generator rotor shaft also rotates.Coupling? Ask me The


System OverviewGenerator Then,

the generator converts the mechanical(rotating) energy into electrical energy


Generator Side Turbine side



I get it !!

How the electrical generator work?

How AC generator work?

AC Generator

Single Phase Generator/ Alternator

Prepared by @ Ms.Soh Ley Bau


Types of Generators Turbo

Generator (Cylindrical

Rotors)Turbine Generator Salient pole


Hydro Generator Diesel Generator

Salient Pole Generator

Salient Pole Generator

Hydroelectric Plant (Chenderoh, Sg Perak)

Salient Pole Generator Stator Windings~ Cameron Highland

Salient Pole RotorA 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

Solid 6 pole machine with brushless exciter

Salient Pole GeneratorRotor Pole Rotating Type Exciter

Salient Pole Rotor Cameron Highland

Salient Pole Rotor Kenyir (112MVA, 24 poles)

Salient Pole Generator Diesel


Salient Pole Generator 6.6kV

Black Start Diesel Generator (PD1)

Salient Pole Generator Diesel Generator,12 poles

What are thefunctions of generator in the Power Utility Industry?


To convert the rotational mechanical energy (steam turbine) into electrical energyMain exciter Generator Steam Turbine

IntroductionTo supply energy to the power grid and route some power to machine auxiliaries (via the Unit Transformer)

One-line diagram for generator and negenerator transformer

Layout of Power Plant

Pressure Rise in a Transformer

TransformerTransformer-Phase to Earth Fault

TransformerTransformer-Phase to Earth Fault

TransformerTransformer-Phase to Earth Fault

Split Generator Shaft

Generator Main Circuit Breaker (SF6)

Generator Main Circuit Breaker (SF6)

Components of GMCB

Generator ConstructionStator Rotor


Generator Construction Main


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

Stator Stator consists

of stator core,stator frame, slot wedges and etc. Function: -Armature- produce output of the generator

Stator ConstructionStator Frame -Special explosion proof design- In case any gas explosion inside, it provides a safe tight housing -Material :No.1 SM41 AP, Material of JIS G 3106 Rolled Steel for welded Construction and is tested to be free from cracks etc. by a supersonic test

Stator ConstructionEnd winding Stator core Wedge

Stator Construction Stator CoreThe 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.

Stator core

Figure : Side view of the stator core *Note : Air-cooled generator in Serdang power station

Stator Construction

Slot WedgeFunction: 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.

Stator Construction

Slot WedgeWedge is located on the top of each slot

End winding

Stator Construction Stator 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.

Stator Lamination *Stator Core

Stator Lamination

Stator Construction Stator core


Stator Construction

Stator core endFunctions:

-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.

Effect of the Flexible Mounting

Flexible 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.

Flexible Mounting

Rotor Construction

Rotor shaft of an inner cooled generatorPole face

Rotor Forging

@soh-Serdang GT5Prepared by @ Ms.Soh Ley Bau 65

Rotor Construction Rotor coil

Example of rotor end winding *Serdang

Power Station Nov.2003,Unit 2

Rotor Construction Rotor Coil Material

: cold worked silver bearing

copper Function: Field

coil of the generator

@Unit 1 SJSSAA,kapar(Oct 03)

Rotor ConstructionRotor

Coupling at turbine side

Rotor Construction

Retaining ring

@Unit 1 SJSSAA,kapar(Oct 03)

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

@Sohlb Serdang GT5

Rotor Construction@Unit 1 SJSSAA,kapar(Oct 03)

End windings of the rotor coil

Generator Parts


Generators Journal BearingBearing # 5 (Turbine side)

Bearing # 6 (Excitation side)

@Unit 1 SJSSAA,kapar(Oct 03)


Generators 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.BACK

Bearing BracketTop half of bearing bracket Bottom half of bearing bracket Rotating Rectifier

NEXTMain Exciter side

Bearing Bracket@Unit 1 SJSSAA,kapar(Oct 03)

Dismantle the top half bearing bracket using overhead crane


Bearing 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.




Gland seal@Unit 1 SJSSAA,kapar(Oct 03)

Gas tight enclosure for hydrogen cooled generator

Function: -To prevent hydrogen gas leakage along the shaft


Gland seal


Seal ringPosition of seal ring Gland seal

Seal ring (Bottom half)

Seal ring


Air Gap BaffleAir Gap Baffle Function: -To separate the high pressure and the low pressure ventilation zones at the exciter end of the rotor & stator.


Blower- 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.


BlowerBlower Blade Material: Ni-Cr-Mo steel

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


Blower Shroud


Gas cooler/Hydrogen Cooler


Gas 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. (a) -Cooling tubes with spiral copper fins are used as shown (b). -The cold gas temperature is designed to maintain below 45rC when the cooling water temperature is 40 rC . NEXT


Gas Cooler Hydrogen Cooler1.

2. 3. 4.

During generator operation, electrical resistance heating in the gen.windings-creates large amount of heat This heat is removed from gen.windingscirculating hydrogen gas through windings Circulation is accomplished by cooling fan. The heat from hydrogen gas is then removed by cooling water flowing through hydrogen coolers BACK

Generator Exciter System Fundamentals

Excitation 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 pre