COIL & INSULATION MANUFACTURING SHOP

COIL & INSULATION MANUFACTURING SHOP

(BLOCK-IV)

Introduction

As the complete one peace coil is not practicable so the coils are manufactured in two parts, upper and lower bars. Out of the various BLOCKS as mentioned before the coil and insulation manufacturing block is BLOCK-4. This block is known as the COIL AND INSULATION MANUFACTURING block.

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 as mentioned below:

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 No. 3- 464 i.e. Robel bar centre.

BAY-III:         Insulation detail shop: Manufacturing of hard insulation & machining of hares insulation part (Glass Textolite) such as packing, washer, insulation box, wedges etc. & CNC taping machine.

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

Why do we call it bar?

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.

Turbo-Generators: The manufacturing of bars of standard capacity such as 100MW, 130MW, 150MW, 210/235MW, 210/250MW, 500MW. The plant has capacity and technology to manufacture 800MW and 1000MW generators.

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.

Ø  T => First alphabet signifies the type of generator i.e. turbo- generator or Hydro generator.

Ø  H/A => Second alphabet stands for the cooling media used for the cooling of rotor i.e. hydrogen gas or air

Ø  R/D/F/I => Third alphabet signifies the type of cooling of rotor e.g. radial, indirect, forced, direct etc.

Ø  I/D/F => Last alphabet stands for the type of cooling of stator e.g. indirect cooling, direct cooling, and forced cooling

Ø  W => Cooling media used for cooling of stator coil e.g. water.

Sections in Block IV

(a) Assembly Section

·        Mechanical Assembly Section: - It is equipped with small size drilling machines, welding sets and hydraulic testing equipment for manufacturing turbo-generator mechanical assemblies.

·        Close Cubical Assembly Section

(b) Stator Bar Winding Section

·        Conductor cutting, insulation and transposition section having facilities for transposing the bars.

·        Stack consolidation section, forming and lug brazing sections have block type hydraulic press, steel former and induction brazing installations respectively.

·         Insulation taping sections with automatic taping facilities in air-conditioned temperature covering maximum slot portion each overhung ay both ends.

·        Baking and pressing section having baking moulds for simultaneous curving of straight and overhead portion with electrical heating.

(c) Armature Winding, Rotor coil and Stator bar Section

Coils are diamond pulled type with Class-B (bitumen) and Class-F (conventional or resin rich discontinuous epoxy insulation) and Class-H Silicon insulation for machines ranging from 5 to 460 KW capacity. This section has the following work centers:-

·        Conductors cutting, U- bending and terminal conductor cutting machines, U- bending machines and terminal baths.

·         Forming and Insulation of DC coils.

·        Main and Interpole Winding: - It is having semi-automatic winding machine.

·        Planking, boat pulling and diamond pulling machine.

·        Insulation and pressing of AC coils: - it is equipped with hydraulic presses of 608 T capacities.

(d)Impregnation Section :-

It is equipped with impregnation tank, ovens for impregnation of DC pole coils.

(e) Insulation Section :-

·        Insulating details, machining is equipped with small size lathes, milling and radial drilling machines and jet cutting saw.

·        Press Molding Section: - It has electrical ovens, hydraulic presses, shearing and circular saw cutting machines for manufacturing press molded components of all the electrical machines.

·        Plastic Molding Section: - Is equipped with various presses for plastic molded parts.

·        Bitumen Mica Tape Manufacture: - Is equipped with mica tape manufacturing machine and lathe for slitting mica tape to the required size.