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MANUFACTURING PROCESS OF 500 MW TURBO GENERTOR STATOR

WINDING BAR

HARSHIT AGARWAL

08070105022

AT BHEL HARIDWAR

INTRODUCTIONINTRODUCTION

In 1956 India took a major step towards the establishment of its heavy engineering industry when BHEL, the

first heavy electrical Manufacturing unit of the country was set up at Bhopal.

BHEL's Heavy Electrical Equipment Plant (HEEP) was set up in technical collaboration with USSR, for the

manufacturing of power plantequipment.

In 1976, BHEL entered into a collaboration agreement with M/sKraftwerkUnion, AG of Germany for

design, manufacturing, erection and commissioning of large size steam turbines.

More than 40 percent of the country's electrical energy is generated from the power equipment

supplied by BHEL,Haridwar.

MANUFACTURING BLOCKS:

.

BLOCK I:ELECTRICAL MACHINE BLOCK, IS DESIGNED TO

MANUFACTURING OF TURBOGENERATORS

BLOCK II: FABRICATION BLOCK

BLOCK III: TURBINE BLADE BLOCK

BLOCK IV: COIL & INSULATION MANUFACTURING &

APPARATUS & CONTROL GEAR MANUFACTURING BLOCK

BLOCK V: FEEDER BLOCK AND KNOWN AS FABRICATION AND FORGE BLOCK

BLOCK VI: STAMPING AND DIES MANUFACTURING BLOCK

BLOCK VII: WOODWORKING BLOCK

BLOCK VIII: HEAT EXCHANGER BLOCK, IS DESIGNED TO MANUFACTURE HEAT EXCHANGER

UNIT FOR STEAM TURBINES.

COIL & INSULATION MANUFACTURING SHOP (BLOCK-IV)

Block-4 is a feeder block for insulating items, winding with class-B Bituminous insulation

and sheet metal components for all the products of Block-1 i.e. Turbo-generators, Hydro-

generators, A.C. and D.C. machines

There are three BAYS in this block each bay manufactures stator bars and coils for

different machines

BAY-I: Bar winding shop:manufacturing of stator winding bars of generator

BAY-II:Manufacturing of heavy duty generator stator bars with New CNC M/c

BAY-III: Insulation detail shop:Manufacturing of hard insulation & machining of hares insulation part

(GlassTextolite) such as packing, washer, insulation box, wedges etc

Bar Shop:This shop is meant for manufacturing of stator winding coils of turbo-generator and hydro

generator

Layout of CIM, Block-IV

Sections in Block IV

1) Assembly Section

It is equipped with small size

• Drilling machines

• Welding sets

• Hydraulic testing equipment for manufacturing turbo-

generator mechanical assemblies.

2) Stator Bar Winding Section

It is equipped with

• Conductor cutting, insulation and transposition section.

• Stack consolidation section, forming and lug brazing

sections.

• Insulation taping sections with automatic taping facilities

in air-conditioned

3) Impregnation Section

It is equipped with

• Impregnation tank

• Ovens for impregnation of DC pole coils.

4) Armature Winding, Rotor coil and Stator bar Section

It is equipped with

• Conductors cutting.

• U- bending and terminal conductor cutting machines.

• Semi-automatic winding machine.

• Planking, boat pulling and diamond pulling machine.

• Insulation and pressing of AC coils.

5) Insulation Section

It is equipped with

• Small size lathes.

• Milling and radial drilling machines.

• Jet cutting saw.

• Electrical ovens & Hydraulic presses.

• Plastic Molding Section

Types of Generators

The generator may be classified based upon the cooling system used in the generators such as:THRI, TARI,

THDI, THDD, THDF, THFF, and THW

Stands for type of

generator

• T- Turbo Generator

• H- Hydro Generator

Stands for the cooling

media for Rotor

• H- Hydrogen gas

• A- Air

Stands for the type of

cooling for Rotor

• R- Radial

• D- Direct

• F- Forced

• I- Indirect

Stands for type of cooling

for Stator

• I- Indirect

• D- Direct

• F- Forced

Stands for cooling media

used for Stator coil

• W- Water

It is quite difficult (rather impossible) to manufacture, handle and wind in the stator slot of generator of

higher generation capacity because of its bigger size and heavy weight. That is why we make coil in two

parts. One part its bottom part of coil called bottom or lower bar and other part of coil is called top bar or

upper bar.

Why do we call it bar?

Set Type Upper Ordinary Upper Terminal Lower Ordinary Lower Terminal Total Bars No. of Bus

Bars

500MW THDF 42 6 42 6 96 6

210MW THW 54 6 54 6 120 9

250MW THRI 48 12 48 12 120 9

No. of Bars in current products

Poor Resin orMicalasticinsulation system

In this type of insulation the bond content in the resin is 5 – 7% and insulating material is prepared with

accelerator treatment. The temperature control need is not required. The insulating material is applied on

job and then same is impregnated (fully dipped) in the resin.

Resin System:

Rich Resin or Thermo-reactive insulation system:

In this type of insulation system the bond content in resin is 35 – 37 %. The raw materials are ready to use

and require preservation and working on temperature 20 – 250C. Its shelf life is one year when kept at a

temperature of 200C which could be increased when kept at temperature of 50C.

INSULATION CLASSIFICATION:

Class YClass Y

• Upto90 °C

• Cotton, Silk, or Paper.

Class AClass A

• Upto105 °C

• ReinforcedClass-Y materials with impregnated varnish.

Class EClass E

• Upto120 °C

• Cotton lamination & Paper lamination.

Class BClass B

• Upto130 °C

• Inorganic material is hardened with adhesives.

Class FClass F

• Upto150 °C

• Class-B materials that are upgraded with adhesives.

Class HClass H

• Upto180 °C

• Made of inorganic material glued with silicone resin.

Class CClass C

• > 180 °CUpto220 °C

• Made of 100% inorganic material

Transposition

Transposition means changing/shifting of position of each conductor in active core (slot) part.

• After cutting the required number of conductors

• The conductors are arranged on the comb in staggered manner and then bends are given to the

conductors with the help of bending die at required distance.

• Then the conductors are taken out from the comb and die and placed with their ends in a line and

transposition is carried out.

• This process is repeated for making another half of the bar which would be mirror image of the first half.

• The two halves of the bar are overlapped over each other and a spacer is placed between the two halves.

Need of transposition.

1. To reduce eddy current losses.

2. Equalize the voltage generator.

3. To minimize skin effect of ac current.

Transposition is done in two ways:

Half Pitch Transposition:In this transposition, the first conductor at one end of the bar becomes the last

conductor at the other end of the bar.

Full Pitch Transposition:In this method of transposition, the first conductor at one end of the bar becomes

the last conductor in the mid of the bar and then again becomes the first conductor at the other end of the

bar.

TestingTan δ test:

• This test is carried out to ensure the healthiness of dielectric (Insulation) i.e. dense or rare & measured the

capacitance loss.

• Bar will act as capacitor when it is laid in the stator of the generator.

• SchearingBridge which works on the principle of wheat-stone bridge is used to find the unknown capacitance of

the bar.

• For good efficiency, capacitance of the bar should be high but we never approach pure capacitance.

• Bar is wrapped with aluminum to make the bar conductive throughout the outer surface of the bar. The two

conducting material i.e. the aluminum sheet and the conductors of the bar act as two plates of the capacitor

and the insulation on the bar act as dielectric medium for the capacitor thus the capacitance is found.

• Of angle of deviation due to impurity in the insulation is obtained from the formula:C4 * R4 * 10^-4 = tan δ

H.V. Test:

• Each bar is tested momentary at high voltage increased gradually to three times higher than rated voltage.

• This test is also known as insulation test because this test is performed to check the insulation of the bar.

• For 500 MW the working voltage of the bar is 64.5 KV & for 210 MW the working voltage of the bar is 63 KV.

• In this test the bar which is already wrapped with aluminum is used.

• High voltage is applied to the bar using auto-transformer and it is increased in steps according to the working

voltage of the generator. If the insulation is weak the bar will puncture at the place of weaker insulation.

• If any of the bar fails this test i.e. bar is punctured at any point then the bar is sent back for re-insulation and all

the processes are repeated again

2-Pole machine with the following features:

Direct cooling of stator winding with water.

Direct hydrogen cooling for rotor.

Micalasticinsulation system.

Spring mounted core housing for effective transmission of vibrations.

Brushless Excitation system.

Vertical hydrogen coolers

500 MW Turbo generators at a glance

Important dimensions & weights:

Heaviest lift of generator stator : 255 Tons

Rotor weight : 68 Tons

Overall stator dimensions [L*B*H] : 8.83m*4.lm*4.02m

Rotor dimensions(Dia. and length) : 1.15m and 12.11m

Total weight of turbo generator : 428 Tons

Salient technical data:

Rated output: 588 MVA , 500 MW

Terminal voltage: 21 KV

Rated stator current: 16 KA

Rated frequency: 50 Hz

Rated power factor: 0.85 Lag

Efficiency: 98.55%

Picture Of Bars

THANK YOUTHANK YOU