Harshitagarwal 111109034529-phpapp02

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

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 – 25
0
C. Its shelf life is one year when kept at a
temperature of 20
0
C which could be increased when kept at temperature of 5
0
C.

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.

Testing
Tan 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%

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