Presentation

MANUFACTURING AND MANUFACTURING AND DESIGN OF DESIGN OF

INSULATION SYSTEM INSULATION SYSTEM FOR FOR

AIR COOLED TURBO AIR COOLED TURBO GENERATOR GENERATOR

BY V.P.I PROCESSBY V.P.I PROCESS

Profile of B.H.E.LProfile of B.H.E.L Bharat Heavy Electrical Limited (BHEL) is today Bharat Heavy Electrical Limited (BHEL) is today

the largest engineering enterprise of India with an the largest engineering enterprise of India with an excellent track record of performance excellent track record of performance

BHEL manufactures over 180 products and BHEL manufactures over 180 products and meets the needs of core-sectors like power, meets the needs of core-sectors like power, industry, transmission, transportation (including industry, transmission, transportation (including railways), defense, telecommunications, oil railways), defense, telecommunications, oil business, etc. business, etc.

Products of BHEL make have established an Products of BHEL make have established an enviable reputation for high quality and reliability enviable reputation for high quality and reliability

prefacepreface Power is the basic necessity for Power is the basic necessity for

economic development of a country. economic development of a country. production of electrical energy its production of electrical energy its

per capital consumption deemed as per capital consumption deemed as an index of standard of living. an index of standard of living.

An AC generator works on the An AC generator works on the principle of ‘principle of ‘Electro Magnetic Electro Magnetic InductionInduction’. ’.

Turbo generators are machines Turbo generators are machines which can generate high voltages which can generate high voltages and capable of delivering KA of and capable of delivering KA of currents currents

the designer should be cautious in the designer should be cautious in designing the winding insulation. designing the winding insulation.

insulation design plays a major role insulation design plays a major role on the life of the Turbo Generator on the life of the Turbo Generator

IntroductionIntroduction

First half we discuss about First half we discuss about manufacture of a statormanufacture of a stator

The latter half we stress more on The latter half we stress more on insulation design by V.P.I processinsulation design by V.P.I process

Defination of insulation Defination of insulation

manufacture of generatormanufacture of generator

generator manufacturing can be generator manufacturing can be broadly divided into three main broadly divided into three main parts:parts:

1. Stator manufacture 1. Stator manufacture 2. Rotor manufacture2. Rotor manufacture 3. Exciter manufacture3. Exciter manufacture

fLowchart of various stages I a generator manufacture

STATOR MANUFACTURE STATOR MANUFACTURE PROCESS:PROCESS:

Stator core construction and Stator core construction and Coil construction and their assembly. Coil construction and their assembly.

Stator core constructionStator core construction

1.PREPARATION OF STATOR 1.PREPARATION OF STATOR LAMINATIONSLAMINATIONS

a RECEPTION OF SILICON STEEL a RECEPTION OF SILICON STEEL ROLLS ROLLS

b SHEARING b SHEARING c BLANKING AND NOTCHINGc BLANKING AND NOTCHING:: i) Compound notching i) Compound notching ii) Individual notching ii) Individual notching

d. d. DEBURRING OPERATIONDEBURRING OPERATION e e VARNISHING:VARNISHING: sheets are dried at a sheets are dried at a

temperature of around 260 – 350 oCtemperature of around 260 – 350 oC

The laminations are subject to various The laminations are subject to various teststests

xylol test xylol test

mandrelmandrel

hardnesshardness

I.RI.R

. STATOR CORE ASSEMBLY. STATOR CORE ASSEMBLY

A A TRAIL PACKET ASSEMBLYTRAIL PACKET ASSEMBLY B B NORMAL CORE ASSEMBLYNORMAL CORE ASSEMBLY i) Stepped packed assemblyi) Stepped packed assembly ii) ii) Normal packet assemblyNormal packet assembly a)In process pressings (venky ko a)In process pressings (venky ko

pooch)pooch) b) Fitting of clamping bolts: b) Fitting of clamping bolts:

STATOR WINDING INSULATION STATOR WINDING INSULATION SYSTEM FEATURES SYSTEM FEATURES

Strand InsulationStrand Insulation Turn InsulationTurn Insulation Ground wall Insulation Ground wall Insulation

CLASSIFICATION OF CLASSIFICATION OF INSULATING MATERIAL:INSULATING MATERIAL:

Picture of above shit Picture of above shit

Stator WindingStator Winding

The most prime part of a winding is The most prime part of a winding is insulationinsulation

MANUFACTURE OF STATOR MANUFACTURE OF STATOR COILS:COILS:

A)For resin poor processA)For resin poor process Reception of copper Reception of copper

conductors:conductors: TranspositionTransposition Putty operation:Putty operation: Stack consolidation:Stack consolidation: Bending:Bending: Final taping:Final taping:

FOR RESIN RICH PROCESSFOR RESIN RICH PROCESS The coil manufacture is same as in The coil manufacture is same as in

case of resin poor but differ in a few case of resin poor but differ in a few stages stages

Putty work:Putty work: Final tapingFinal taping Final baking:Final baking:

10.1 ADVANTAGES OF RESIN POOR SYSTEM OF 10.1 ADVANTAGES OF RESIN POOR SYSTEM OF INSULATION:INSULATION:

It has better dielectric strengthIt has better dielectric strength Heat transfer coefficient is much betterHeat transfer coefficient is much better It gives better capacitance resulting in less dielectric losses It gives better capacitance resulting in less dielectric losses

due to which the insulation life will be moredue to which the insulation life will be more The cost will be less and it is latest technologyThe cost will be less and it is latest technology Reduction in time cycle and consumption for MW also less Reduction in time cycle and consumption for MW also less

and it gives high qualityand it gives high quality

DISADVANTAGES OF RESIN POOR SYSTEM OF DISADVANTAGES OF RESIN POOR SYSTEM OF INSULATION:INSULATION:

If any short circuit is noticed, the repairing process is If any short circuit is noticed, the repairing process is difficult and need of excess resin from outside.difficult and need of excess resin from outside.

Dependability for basic insulating material on foreign Dependability for basic insulating material on foreign supplysupply

Assembly of stator:Assembly of stator: Reception of stator core:Reception of stator core: Winding holder’s assembly Winding holder’s assembly

STIFFNER ASSEMBLYSTIFFNER ASSEMBLY Eye formation Eye formation Connecting rings assembly:Connecting rings assembly: Phase connectors: Phase connectors:

• ADVANTAGES OF RESIN RICH SYSTEM OF INSULATION:ADVANTAGES OF RESIN RICH SYSTEM OF INSULATION: Better quality and reliability is obtained Better quality and reliability is obtained In case of any fault (phase - ground/ phase – phase short) In case of any fault (phase - ground/ phase – phase short)

carrying the repair process is very easy.carrying the repair process is very easy. Addition of excess resin will be avoided because of using Addition of excess resin will be avoided because of using

resin rich mica taperesin rich mica tape

• DISADVANTAGES OF RESIN RICH SYSTEM OF DISADVANTAGES OF RESIN RICH SYSTEM OF INSULATION:INSULATION:

It is a very long procedureIt is a very long procedure Due to fully manual oriented process, the cost is moreDue to fully manual oriented process, the cost is more It is possible to process stator bars only.It is possible to process stator bars only. Even though the advantages and disadvantages of both Even though the advantages and disadvantages of both

the process are explained above, resin poor process is the process are explained above, resin poor process is the best of all, as the resin content used is almost only the best of all, as the resin content used is almost only 35% compared to resin poor process and also show good 35% compared to resin poor process and also show good insulation properties justified in the later sections.insulation properties justified in the later sections.

THE VPI PROCESSTHE VPI PROCESS

INTRODUCTION TO VACUUM INTRODUCTION TO VACUUM PRESSURE IMPREGNATION PRESSURE IMPREGNATION SYSTEM (VPISYSTEM (VPI ) )

Drawback of earlier VPI SYSTEM Drawback of earlier VPI SYSTEM

Vacuum Pressure Impregnation of Vacuum Pressure Impregnation of resin poor insulated jobs resin poor insulated jobs

1. Preheating1. Preheating Lifting and shiftingLifting and shifting Vacuum cycleVacuum cycle Vacuum drop testVacuum drop test Heating the resinHeating the resin Resin admission.Resin admission. Resin settlingResin settling Pressure cyclePressure cycle

Aeration Aeration Post curing cyclePost curing cycle CleaningCleaning

FACILITIES AVAILABLE IN VPI FACILITIES AVAILABLE IN VPI PLANT IN BHELPLANT IN BHEL

Steam furnace for preheatingSteam furnace for preheating Size of chamber: 2 * 2 * 6.5 MSize of chamber: 2 * 2 * 6.5 M Maximum temperature: 160Maximum temperature: 160CC Electrical power consumption: Electrical power consumption:

75KW75KW Work place: 1425Work place: 1425 Work centre: 3215Work centre: 3215 Stream inlet: 200-250Stream inlet: 200-250CC

Impregnated tubs for keeping Impregnated tubs for keeping jobsjobs

For vertical impregnation: As For vertical impregnation: As per respective tech. Document.per respective tech. Document.

For horizontal impregnation: For horizontal impregnation: As per respective tech. Document As per respective tech. Document

Specifications of plant:Specifications of plant: Impregnation mediumImpregnation medium Epoxy resin (class F solvent free) and hardener mix in 1:1 Epoxy resin (class F solvent free) and hardener mix in 1:1

ratio as per TG34967ratio as per TG34967 Epoxy resin (class F solvent free) and hardener mix in 1:1 Epoxy resin (class F solvent free) and hardener mix in 1:1

ratio as per TG34931ratio as per TG34931

Horizontal impregnation chamberHorizontal impregnation chamber Diameter: 4000mmDiameter: 4000mm Cylindrical length: 9000 mmCylindrical length: 9000 mm Operating over pressure: 6 barOperating over pressure: 6 bar Operating vacuum: 0.15 mbarOperating vacuum: 0.15 mbar Operating temperature: 90Operating temperature: 90CC Loading weight of impregnation object: maximum of 120 Loading weight of impregnation object: maximum of 120

tonnestonnes Maximum leakage rate: less than 1mbar/lit/sec.Maximum leakage rate: less than 1mbar/lit/sec. Moving load: 140 tonnes.Moving load: 140 tonnes. Static load: 170 tonnesStatic load: 170 tonnes

Pressure medium for impregnationPressure medium for impregnation Pressure medium: dry nitrogenPressure medium: dry nitrogen Operating pressure: 6 bar.Operating pressure: 6 bar. Nitrogen storage capacity: 52cubic meter at 25 Nitrogen storage capacity: 52cubic meter at 25

bar.bar. Resin storage capacityResin storage capacity Total storage: 5*9000L+1*3000LTotal storage: 5*9000L+1*3000L Operating parameters of each tankOperating parameters of each tank Operating vacuum: 0.5mbarOperating vacuum: 0.5mbar Operating over pressure: 0.5barOperating over pressure: 0.5bar Operating temperature: 80Operating temperature: 80CC Resin filters(stainless steel washable)Resin filters(stainless steel washable) Filter fineness: 150micronsFilter fineness: 150microns Output (maximum): 1000lits/minOutput (maximum): 1000lits/min

Vacuum systemVacuum system Root pumps: 2No.s, 5.5KW eachRoot pumps: 2No.s, 5.5KW each Suction capacity: 2000cubic meter/hrSuction capacity: 2000cubic meter/hr Vacuum pumps(4No.s, 7.5KW each)Vacuum pumps(4No.s, 7.5KW each) Suction capacity: 250 cubic meter/hrSuction capacity: 250 cubic meter/hr This system is provided with separator filter with activated carbon filters, to protect This system is provided with separator filter with activated carbon filters, to protect

the vacuum pumps from resin and hardener vapours.the vacuum pumps from resin and hardener vapours. Refrigeration systemRefrigeration system The resin inside the tanks has to be stored at 10The resin inside the tanks has to be stored at 1022C. this can be stored for indefinite C. this can be stored for indefinite

period with a brine chilling/refrigeration system.period with a brine chilling/refrigeration system. The brine storage capacity: 1*25000L+1*26000LThe brine storage capacity: 1*25000L+1*26000L Composition of brine: 40%Mono Ethylene glycol and 60%water Composition of brine: 40%Mono Ethylene glycol and 60%water Heating and cooling systemHeating and cooling system The heating of resin in the storage tanks and the impregnation chamber is by The heating of resin in the storage tanks and the impregnation chamber is by

circulating the heated brine through the heat exchangers, to heat by saturated circulating the heated brine through the heat exchangers, to heat by saturated steam. The hot brine is cooled to about 40steam. The hot brine is cooled to about 40C by circulating water through coolers and C by circulating water through coolers and then the brine is chilled to -10then the brine is chilled to -10C and stored in the tanks.C and stored in the tanks.

Post heating of jobPost heating of job Explosion proof steam drier and electrical heating superposed. Explosion proof steam drier and electrical heating superposed. Size: 7*4.5*4.5MSize: 7*4.5*4.5M Maximum weight of job: 80 tonnesMaximum weight of job: 80 tonnes Maximum temperature: 150Maximum temperature: 150CC Indirectly heated hot air circulating oven (gas fired) Indirectly heated hot air circulating oven (gas fired) Size: 9*4.5*4.5MSize: 9*4.5*4.5M Maximum weight of job: 170 T/120T with facility for rotation.Maximum weight of job: 170 T/120T with facility for rotation. Maximum temperature: 150Maximum temperature: 150CC

DATA COLLECTION OF SAMPLESDATA COLLECTION OF SAMPLES

INDO-BHARAT-II ROTORINDO-BHARAT-II ROTOR

RESIN POOR SYSTEM RESIN RICH SYSTEM

1. The insulation tape used in this system has 40% resin.

2. This method follows thermosetting process.

3. There is a need for addition of resin from outside.

4. Reduction in time cycle for this process

1. No tests are carried out while at

processing 2. Processing of bars along with stator

and with conductors and processing of exciter Coils along with exciter is possible.

3. The cost of repair is more

4. The overall cost is less compared to resin rich system.

1. The insulation tape used in this is 7% of 40% resin.

2. Same as in resin poor. 1. Further addition of resin is not

required from outside. 2. It is very long process and

time consuming while at processing stage.

3. Tests are being carried out Stage. 1. Processing of stator bars is

only possible in resin rich systems.

2. Repairing work is easy.3. The total cost in this process is more.

JUSTIFICATIONJUSTIFICATION

Justification can be done by two testsJustification can be done by two tests HV and TAN δ testsHV and TAN δ tests

PRESENT INSULATION PRESENT INSULATION SYSTEMS IN THE WORLDSYSTEMS IN THE WORLD

1. Vacuum pressure impregnation 1. Vacuum pressure impregnation (VPI) of individual coils and bars(VPI) of individual coils and bars

2. Global VPI of complete stators2. Global VPI of complete stators 3. Hydraulic molding of individual 3. Hydraulic molding of individual

coils and bars using resin-rich tapescoils and bars using resin-rich tapes 4. Press curing of individual coils 4. Press curing of individual coils

and bars, also using resin-rich tapesand bars, also using resin-rich tapes

Westinghouse Electric Co.: Thermalastic™Westinghouse Electric Co.: Thermalastic™ General Electric Co. General Electric Co. :Micapals I anII™,EpoxyMicaMat™, Micapal :Micapals I anII™,EpoxyMicaMat™, Micapal

HT™, and hydromat™HT™, and hydromat™ Alsthom, GEC Alsthom, Alstom Power: Alsthom, GEC Alsthom, Alstom Power:

Isotenax™, Resitherm™,Isotenax™, Resitherm™, Siemens AG, KWU: Micalastic™Siemens AG, KWU: Micalastic™

ABB Industrie AG: Micadur™,ABB Industrie AG: Micadur™, Toshiba Corporation: Tosrich™ and Toshiba Corporation: Tosrich™ and

Tostight- I™Tostight- I™ Mitsubishi Electric CorporationMitsubishi Electric Corporation Hitachi, Ltd.: Hi-Resin™, Hi-Mold™, and Hitachi, Ltd.: Hi-Resin™, Hi-Mold™, and

Super Hi-Resin™Super Hi-Resin™

Summary of Present-Day Insulation Summary of Present-Day Insulation SystemsSystems

A NEW hype IN INSULATION A NEW hype IN INSULATION SYSTEMSYSTEM

MICALASTICMICALASTIC1.1. The MICALASTIC Insulation in The MICALASTIC Insulation in

ITAIPU™ITAIPU™

2.2. Manufacturing and DesignManufacturing and Design

3.3. Fitting of Roebel Bars into Slots:Fitting of Roebel Bars into Slots:

4.4. Thermal StabilityThermal Stability

CONCLUSION: CONCLUSION: