MANUFACTURING PROCESS OF 600 MW TURBO GENERTOR STATOR WINDING

BAR

Presented by:Anurag vermaIMS engg. CollegeGhaziabad

AT BHEL HARIDWAR

INTRODUCTIONINTRODUCTIONIn 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 plant equipment.

In 1976, BHEL entered into a collaboration agreement with M/s Kraftwerk Union, 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 BLOCKBLOCK 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 (Glass Textolite) 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-conditioned3) Impregnation Section  

It is equipped with• Impregnation tank• Ovens for impregnation of DC pole coils.

4) Armature Winding, Rotor coil and Stator bar SectionIt 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 GeneratorsThe 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 or Micalastic insulation systemIn 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 Y

• Upto 90 °C• Cotton, Silk, or Paper.

Class A• Upto 105 °C

• Reinforced Class-Y materials with impregnated varnish.

Class E• Upto 120 °C

• Cotton lamination & Paper lamination.

Class B• Upto 130 °C

• Inorganic material is hardened with adhesives.

Class F• Upto 150 °C

• Class-B materials that are upgraded with adhesives.

Class H• Upto 180 °C

• Made of inorganic material glued with silicone resin.

Class C• > 180 °C Upto 220 °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.

• Schearing Bridge 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 600 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.Micalastic insulation system.Spring mounted core housing for effective transmission of

vibrations.Brushless Excitation system.Vertical hydrogen coolers

600 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 , 600 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 YOU