bhel - training report punnet

8/10/2019 Bhel - Training Report Punnet

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INDUSTRIAL TRAINING REPORT

BHARAT HEAVY ELECTRICALS LIMITED

RANIPUR, HARIDWAR

AREA OF TRAINING: ROTOR AND STATOR WINDING ASSEMBLY OF THRI

AND LSTG

Submitted to the

Department of Electrical Engineering

in partial fulfillment of the requirements for the degree of

Bachelor of Technology

in

Electrical Engineering

JSS Academy of Technical Education, NOIDA

U.P. Technical University

SUBMITTED BY: SUBMITTED TO:

Puneet Kapoor Mr. Nirmal Kr. Aggarwal

(1109120122) (Indust. Training Presentation Coordinator)

VII-EE-B Electrical Engg. Deptt.

JSSATE, NOIDA


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ACKNOWLEDGEMENT

Training has an important role in exposing the real life situation in an industry. It was

a great experience for me to work on training at BHARAT HEAVY

ELECTRICALS LIMITED through which I could learn how to work in aprofessional environment.

Now, I would like to thank the people who guided me and have been a constant

source of inspiration throughout the tenure of my summer training.

I am sincerely grateful to MR. RAJ SINGH (Manager)at HRDC, BHEL Haridwar

who allowed me to pursue my summer training at the plant and rendered me his

valuable assistance, constant encouragement and able guidance which made this

training actually possible.

I wish my deep sense of gratitude to MR. SANJAY KUMAR (Asst. GeneralManager) whose affectionate guidance has enabled me to complete this training

successfully. I wish my deep sense of gratitude to Dr. V. K CHANDNA (HOD: EE

Department)whose guidance and encouragement made my training successful.

Puneet Kapoor


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CONTENTS

Topic Page No.

1.

BHELAn Overview. 1

2.

HEAVY ELECTRICAL EQUIPMENT PLANT (HEEP). 5

3. ELECTRICAL MACHINES (BLOCK1) 11

I. TURBO-GENERATOR. 12

II.

LARGE SIZE TURBO-GENERATOR. 13

III. COMPONENTS OF TURBO-GENERATOR. 14

a)

STATOR

1)

STATOR CORE.

2) STATOR WINDING.

3)

END COVERS.

b) ROTOR

1) STEPS IN ROTOR MACHINING.

IV. EXCITATION SYSTEM. 19

a)

EXCITER.

V.

BAY-4 (SMALL AND MISCALLANEOUS COMPONENTS) 20

VI. TEST STANDS. 26

VII. LSTG TEST STANDS. 26

VIII.

TESTING. 26

a) HELIUM LEAK TESTS

b) HYDROGEN TESTING AND PNEUMATIC TESTING.

4. CONCLUSION 27

5. REFERENCES 27


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1

1. BHELAN OVERVIEW

Bharat Heavy Electricals Limited(BHEL) owned by Government of India, is apower plant equipment manufacturer and operates as engineering and manufacturing

company based in New Delhi, India. Established in 1964, BHEL is India's largest

engineering and manufacturing company of its kind. The company has been earning

profits continuously since 1971-72 and paying dividends uninterruptedly since 1976-

77.

BHEL caters to core sectors of the Indian Economy viz., Power Generation's &

Transmission, Industry, Transportation, Telecommunication, Renewable Energy,

Defense, etc. The wide network of BHEL's 14 manufacturing division, four power

Sector regional centres, over 150 project sites, eight service centres and 18 regional

offices, enables the Company to promptly serve its customers and provide them with

suitable products, systems and servicesefficiently and at competitive prices. BHEL

has already attained ISO 9000 certification for quality management, and ISO 14001

certification for environment management.

POWER GENERATION

Power generation sector comprises thermal, gas, hydro and nuclear power plant

business as of 31.03.2001, BHEL supplied sets account for nearly 64737 MW or 65%

of the total installed capacity of 99,146 MW in the country, as against nil till 1969-70.

BHEL has proven turnkey capabilities for executing power projects from concept to

commissioning, it possesses the technology and capability to produce thermal setswith super critical parameters up to 1000 MW unit rating and gas turbine generator

sets of up to 240 MW unit rating. Co-generation and combined-cycle plants have been

introduced to achieve higher plant efficiencies. to make efficient use of the high-ash-

content coal available in India, BHEL supplies circulating fluidized bed combustion

boilers to both thermal and combined cycle power plants.

The company manufactures 235 MW nuclear turbine generator sets and has

commenced production of 500 MW nuclear turbine generator sets.

Custom made hydro sets of Francis, Pelton and Kapian types for different head

discharge combination are also engineering and manufactured by BHEL.

In all, orders for more than 700 utility sets of thermal, hydro, gas and nuclear have

been placed on the Company as on date. The power plant equipment manufactured byBHEL is based on contemporary technology comparable to the best in the world and

is also internationally competitive.

The Company has proven expertise in Plant Performance Improvement through

renovation modernisation and uprating of a variety of power plant equipment besides

specialised know how of residual life assessment, health diagnostics and life

extension of plants.


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POWER TRANSMISSION & DISTRIBUTION (T & D)

BHEL offer wide ranging products and systems for T & D applications. Products

manufactured include power transformers, instrument transformers, dry type

transformers, seriesand stunt reactor, capacitor tanks, vacuumand SF circuitbreakers gas insulated switch gears and insulators.

A strong engineering base enables the Company to undertake turnkey delivery of

electric substances up to 400 kV level series compensation systems (for increasing

power transfer capacity of transmission lines and improving system stability and

voltage regulation), shunt compensation systems (for power factor and voltage

improvement) and HVDC systems (for economic transfer of bulk power). BHEL has

indigenously developed the state-of-the-art controlled shunt reactor (for reactive

power management on long transmission lines). Presently a 400 kV Facts (Flexible

AC Transmission System) project under execution.

INDUSTRIES

BHEL is a major contributor of equipment and systems to industries. Cement, sugar,

fertilizer, refineries, petrochemcials, paper, oil and gas, metallurgical and other

process industries lines and improving system stability and voltage regulation, shunt

compensation systems (for power factor and voltage improvement) and HVDC

systems (for economic transfer of bulk power) BHEL has indigenously developed the

state-of-the-art controlled shunt reactor (for reactive power management on long

transmission lines). Presently a 400 kV FACTS (Felxible AC Transmission System)

projects is under execution.

ACTIVITY PROFILE

PRODUCTS - Industrial Fans

Power Generation & Transmission - Seamless steel Tubes

- Steam Turbine-Generator Sets &

Auxiliaries

- Fabric Filters

- Boiler and Boiler Auxiliaries - AC DC Motors, Variable speed

- Once-through Boilers - AC Drive

- Nuclear Power Generation Equipment - Electronic Control Gear &

Automation

- Hydro Turbine-Generator Sets & Auxiliaries - Equipment- Mini/Micro Hydro Generator Sets - DDC for Process Industry

- Gas Turbine-Generator Sets - Thruster Equipment

- Waste Heat Recovery Boilers - Power Devices

- Heat Exchangers - Energy Meters

- Condensers - Transformer

- Bowi Mills and Tube Mills - Switch gear

- Gravimetric Feeders - Insulator

- Regenerative Air Pre-Heaters - Capacitors

- Electrostatic Precipitators - Broad Gauge AC, AC/DC Loco

Motives

- Bag Filters - Diesel-Electric ShuntingLocomotives


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- Valves - Traction Motors & Control

Equipment

- Pumps - Electric Trolley Buses

- Electrical Machines - AC/DC Electric Multiple Units

- Piping Systems - Drives and Controls for Metro

Systems- Power, Distribution & Instrument Transformers - Battery-Operated Passengers

Vans

- Reactors - X-Mas Trees and Well Heads

- Synchronous Condensers - Cathodic Protection Equipment

- Switchgear - Digital Switching Systems

- Control gear - Rural Automatic Exchange

- Distributed Digital Control for Power

Stations

- Simulators

- Bus Ducts - Wind Electric Generators

- Rectifiers - Solar Powered Water Pumps

- Porcelain Insulators - Solar Water Heating Systems- Ceralin - Photo Votaic Systems

- Defense Equipment

Industries/Transportation/Oil & Gas/ - Reverse Osmoses Desalination

Plants

Telecommunication/Renewable Energy SYSTEMS & SERVICES- Steam Turbine-Generator Sets - Turkey Utility Power Stations/

EPC

- Gas Turbine-Generator Sets - Contracts

- Diesel Engine-Based Generators - Captive Power Plants

- Industrial Steam Generators - Co-generation Systems

- Heat Recovery Steam Generators - Combined Cycle Power Plants

- Fluidised Bed Combustion Boilers - Modernisation & Renovation of

Power

- Drive Turbine Stations and FLA Studies

- Manne Turbines - Switch yards and Substations

- Industrial Heat Exchangers - HVDC Transmission Systems

- Centrifugal Compressor - Shorts sines condensation

Systems

- Industrial Valves - Power system analysis

- Reactors - Electron comissionly and

Operation- Columns - Consultancy services

- Pressure Vessels - Consultancy Services

- Pumps

SUMMARY OF BHEL'S CONTRIBUTION TO VARIOUS CORE SECTORS

POWER GENERATION

THERMAL RATING (MW) NO. OF

SETS

TOTAL

CAPACITY (MW)500 30 15000

250 9 2250210/200 138 28570


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120/125/130 20 2420

195 1 195

110 38 4180

100 6 600

70/67.5 6 410

60 14 84030 5 150

TOTAL

(THERMAL)

267 54615

GAS FRAME SIZE/

SCOPE

NO. OF

SETS

TOTAL


6 17 580

5 13 309

3 6 48

V 94.2 2 2866FA 3 207

STG 24 1190

GEN 4 87

TOTAL (GAS) 74 3437

NUCLEAR RATING (MW) NO. OF

SETS

TOTAL


220 10 2200

TOTAL

(NUCLEAR)

12 3200

TOTAL (THERMAL+GAS+NUCLEAR) 353 61252

HYDRO 402 18735

GRAND TOTAL 755 79987


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2. HEAVY ELECTRICAL EQUIPMENT PLANT (HEEP)

At Hardwar, against the picturesque background of Shivalik Hills, two

important manufacturing units of BHEL are located viz. Heavy Electrical Equipment

Plant (HEEP) & Central Foundry Forge Plant (CFFP). The hum of the construction

machinery working started under Shivalik Hills during early 60s and sowed the seeds

of one of the greatest symbol of Indo Soviet Collaboration Heavy Electrical

Equipment Plant.

Consequent upon the technical collaboration between India and USSR in

1959, BHELs prestigious unit, Heavy Electrical Equipment plant (HEEP), was

established in October, 1963, at Hardwar. It started manufacturing thermal sets in

1967 and now thermal sets of 210, 250 and 500 MW, including steam turbines, turbo-

generators, condensers and all associated equipments, are being manufactured. This

unit is capable of manufacturing thermal sets up to 1000 MW. HEEP-manufactured

gas turbines, hydro turbines and generators, etc., are not only successfully generating

electrical energy within and outside the country, but have also achieved a historic

record of the best operational availability and plant load factor.

The Company is embarking upon an ambitions growth path through clearvision, mission and committed values to sustain and augment its image as a world

class enterprise.

VISION

World-class, innovative, competitive and profitable engineering enterprise providing

total business solutions.

MISSION

The leading Indian engineering enterprise providing quality products systems and


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services in the fields of energy, transportation, infrastructure and other potential areas.

VALUES

Meeting commitments made to external and internal customers.

Foster learning creativity and speed of response.

Respect for dignity and potential of individuals.

Loyalty and pride in the company.

Team playing

Zeal to excel.

Integrity and fairness in all matters.

ESTABLISHMENT AND DEVELOPMENT STAGES

Established in 1960s under the Indo-Soviet Agreements of 1959 and 1960 in the area

of Scientific, Technical and Industrial Cooperation.

DRRprepared in 1963-64, construction started from October '63

Initial production of Electric started from January, 1967.

Major construction / erection / commissioning completed by 1971-72 as per original

DPR scope.

Stamping Unit added later during 1968 to 1972.

Annual Manufacturing capacity for Thermal sets was expanded from 1500 MW to

3500 MW under LSTG. Project during 1979-85 (Sets up to 500 MW, extensible to

1000/1300 MW unit sizes with marginal addition in facilities with the collaboration of

M/s KWU-Siemens, Germany.

Motor manufacturing technology updated with Siemens collaboration during 1984-87.

S.No. Area/ Block Major Facilities Products

1. BlockI

(Electrical

Machines)

Machine Shop., Windings bar

preparation assembling, painting

section, packing& preservation,

over speed balancing, test bed test

stand, babbiting, micalastic

impregnation etc.

Turbo Generator,

Generator exciters,

motors (AC& DC)


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2. BlockII

(Fabrication

Block)

Markings, welding ,Cutting,

straightening, gas cutting press, ,

grinding, assembly, heat

treatment, cleaning & Shotblasting, machining, fabrication of

pipe coolers, painting

Large size fabricated

assemblies/

components for power

equipments

3. BlockIII

(Turbines &

Auxiliary Block)

Machining, facing wax melting,

broaching, assembly preservation

& packing, test stands/ station,

painting grinding, milling,

polishing etc.

Stem turbines, hydro

turbines, gas turbines,

turbine bladders,

special tooling.

4. BlockIV

(Feeder Block)

Bar winding, mechanical

assembly, armature winding,

sheet metal working marching,

copper profile drawing

electroplating, impregnation,

machining & preparation of

insulating components plastic

molding, press molding

Windings for turbo

generators, hydro

generators insulation

for AC & DC motors,

insulating components

for TG, HG & Motors

control panel, contact

relays master control

etc.

5. BlockV Fabrication, pneumatic hammer

for forgings, gas fired furnaces,

hydraulic manipulators

Fabricated parts of

steam turbine, water

box, storage tankhydro turbine parts,

hydro turbines

assemblers &

Components

6. BlockVI Welding, drilling, shot blasting,

CNC flame cutting ,CNC deep

Fabricated parts of

steam turbine water


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(Fabrication) drilling, Shot basting, sheet metal

work, assembly

box, stronger tanks,

hydro turbine parts,

Hydro turbines

assemblies &components,

7. Block- VI

(Stamping & Die

Manufacturing)

Machining, turning, grinding, jig

boring stamping presses, de

varnishing, degreasing & de

rusting, varnishing sport welding,

painting.

Wooden packing,

spacers etc.

8. Block- VII (wood

working)

Wood Cutting, machines,

grinding , packing

Wooden packing,

spacers etc.

9. BlockVIII Drilling ,turning, saw, cutting,

welding, tig welding

LP Heater ejectors

glad, steam cooler oil

coolers, ACG collers,

oil tanks, bearing

covers.

10. Services plat TPS : Power generation

equipment & auxiliaries plat

capacity 12 MW

Power generation

PGP Plat : Boiler Type gasgenerators

Producer gas

Acetylene Plat : A fully

automated plant for acetylene

generation & filling in cylinder

Acetylene gas

Compressor House: 4 No.

Compressors of rating 100 m2 /

min

Compressed air


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Oxygen Plat : 3 air separation unit

4 air compressors

Oxygen gas

Nitrogen gas

132 KV substation : 2 Nose 16.7

MVA/ 11 KV, one no. 20 MVA

& one no. 12.5 MVA 132/6.6 KV

transformer & other allied

equipment

Power supply

11. Motor transport A fleet of vehicles comprising of

cars, jeeps trekkers, buses, mini

buses motorcycles , fire tenders

trucks etc.

Transport service

12. Telecommunication A 2000 line main exchange for

internal communication

3 no Satellite exchange

Telephone service

13. Hydro Turbine Lab 3 test beds with electronic

instrumentation. It consists of

cavitations test bed for reactions

turbine & hydrodynamic test bed

for Impulse turbines facilities for

carrying out filed test at hydro

power sets.

Testing of turbine

models

14. HRDC Class room with audiovisual

facilities workshop with facilities

for turnings fitting machining,

weeding, electrical work

carpentry work

Training to

Employees, VTs

Apprentices,

Contractors &

Customers


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CLIMATIC AND GEOGRAPHICAL CONDITIONS

Hardwar is in extreme weather zone of the Western Uttar Pradesh of India and

temperature varies from 2oC in Winter (December to January) to 45oC in Summer

(April-June); Relative humidity 20% during dry season to 95-96% during rainyseason.

Longitude 78o3' East, Latitude 29o55'5" North.

Height above Mean Sea Level = 275 meters.

Situated within 60 to 100 KMs of Foot-hills of the Central Himalayan Ranges;

Ganges flows down within 7 KMs from the Factory area.

HEEP is located around 7 KMs on the Western side of Hardwar city.

POWER & WATER SUPPLY SYSTEM

40 MVA sanctioned Electric Power connection from UP Grid (132 KV / 11KV / 6.6

KV) (Connected loadaround 185 MVA)

26 deep submersible Tube Wells with O.H. Tanks for water supply.

A 12 MW captive thermal power station is located in the factory premises.

15. Engineering CAD Work stations, personal

computer reprographic facilities

like ammonia printing, semi dry

printing machine, Xerox process,micro filming facilities

Design and drawings

of all products

16. Computer Center ICIMs series 39 DX level 270-

320 computer system HCL

magnum mini compute system ,

ESPL SM32 mini computer

Nexus3500 CAE work station,

PCs etc.

IT services

17. CPL (Central plant

Lab.)

Testing Lab for new materials &

sample components

Testing of components


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3. ELECTRICAL MACHINES BLOCK (BLOCK-I)

INTRODUCTION

Block-I is designed to manufacturing Turbo Generators, Hydro generators and

large and medium size AC and DC Electrical machines.

The Block consist of 4 bays: Bay-1 (36*482 meters), Bay-2 (36*360 meters) and

Bay-3 and Bay-4 of size 24 *360 meters each. For handling and transporting the

various components over-head Crane facilities are available, depending upon the

products manufactured in each Bay. There are also a number of self-propelled

electrically-driven transfer trolleys for the inter-bay movement of components

/assemblies.

Conventional bay -wise broad distribution of products is as follows :

BAY1 ROTOR

SHAFT

MACHINI

NG

ROTOR SHAFT

SLOTTING

ROTOR

WINDING

OVER SPEED

AND

BALANCING

TUNNEL

LARGE SIZE

TURBO

GENERATOR

S

BAY2 EXCITER

SHAFT

MACHINI

NG

STATOR BODY

MACHINING

STATOR

WINDING

TOTAL

IMPREGNATION

TEST BED

BAY--3 ROTOR

SUPPORT

BEARING

SHAFT SEAL

BODY

DC

MOTOR

WINDING

(EARLIER)

BAY--4 COOLING

FANS

MACHINI

NG

ARRANGEMEN

T AND OTHER

PARTS

BASIC TRAINING DEPARTMENTS: -

MACHINE SHOP.

T/G ROTOR WINDING.

H/G IRON ASSEMBLY.

EXCITER. T/G STATOR WINDING.


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TOTAL IMPREGNATION TECHNIQUE.

T/G IRON ASSEMBLY.

T/G MAIN ASSEMBLY.

L.S.T.G ROTOR WINDING.

L.S.T.G STATOR WINDING.

L.S.T.G MAIN ASSEMBLY. TEST BED.

I. TURBO GENERATOR

Turbo generator or A.C. generators or alternators operates on the fundamental

principles of ELECTROMAGNETIC INDUCTION. In them the standard

construction consists of armature winding mounted on stationary element called stator

and field windings on rotating element called rotor. The stator consists of a cast-iron

frame , which supports the armature core , having slots on its inner periphery for

housing the armature conductors. The rotor is like a flywheel having alternating north

and south poles fixed to its outer rim. The magnetic poles are excited with the help of

an exciter mounted on the shaft of alternator itself. Because the field magnets are

rotating the current is supplied through two slip rings. As magnetic poles are

alternately N and S, they induce an e.m.f and hence current in armature conductors.

The frequency of e.m.f depends upon the no. of N and S poles moving past a

conductor in 1 second and whose direction is given by Fleming s right hand rule.

SYNOPSIS OF THE FUNCTION OF T.G.:

1.

The generator is driven by a prime mover which is steam turbine in this case.2.

The other side of generator is provided by a rotating armature of an exciter which

produces A.C. voltage. This is rectified to D.C. by using a rotating diode wheel.

3. The rear end of above exciter armature is mounted by a permanent magnet

generator rotor.

4.

As the above system is put into operation, the PMG produces A.C. voltage.

5. The voltage is rectified by thyristor circuit to D.C.

6.

This supply is given to exciter field. This field is also controlled by taking

feedback from main generator terminal voltage, to control exciter field variation by

automatic voltage regulator. The rectified DC supply out of exciter is supplied to

turbo generator rotor winding either through brushes or central which will be

directly connected to turbo generator. This depends on the type of exciter viz. DCcommutator machines or brushes exciter.

7. The main A.C. voltage is finally available at the stator of Turbo Generator.


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LSTG AREA

II. LARGE SIZE TURBO GENERATOR (LSTG)

In these types of generators steam turbine does the function of prime mover which

rotates the rotor of LSTG and the field winding is supplied D.C. by an exciter.

Main types of T.G. are:-

1. THRI2.

TARI

3. THDI

4. THDD

5. THDF

6. THFF

1stLETTER= (here-T)

= 3-phase turbo generator

2nd

LETTER= (here H or A)

=Medium present for generator cooling

(H= hydrogen, A or L=air)

3rdLETTER=type of rotor cooling employed


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R= radial,

F= direct water cooling

D= direct axial gas cooling)

4th

LETTER= type of as used for stator winding cooling

I= indirect gas cooling

D= direct gas cooling

F= direct water cooling

III. COMPONENTS OF T.G. :-

STATOR

1. Stator frame

2. Stator core

3. Stator winding

4. End covers.

ROTOR

1.

Rotor shaft

2. Rotor windings

3.

Rotor retaining rings

BEARINGS

COOLING SYSTEM

EXCITATION SYSTEM

STATOR

The generator stator is a tight construction supporting and enclosing stator winding,

core and hydrogen cooling medium. Hydrogen is contained within the frame and

circulated by fans mounted at either end of rotor. The generator is driven by a direct

coupled steam turbine at the speed of 3000 rpm.


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The generator is designed for continuous rated output. Temperature detector or other

devices installed or connected within the machine, permits the winding core and

hydrogen temperature, pressure and purity in machine.

STATOR FRAME

The stator frame is used for housing armature conductors. It is made of cylindrical

section with two end shields which are gas tight and pressure resistant. The stator

frame accommodates the electrically active parts of stator i.e. the stator core and the

stator winding.

The fabricated inner cage is inserted in the outer frame after the stator has been

constructed and the winding completed.

STATOR CORE

The stator core is stacked from the insulated electrical sheet steel lamination and

mounted in supporting rings over the insulated dovetail guide bars. In order to

minimize eddy current losses core is made of thin laminations. Each lamination layer

is made of individual sections. The ventilation ducts are imposed so as to distribute

the gas accurately over the core and in particularly to give adequate support to the

teeth.


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The main features of core are

1. To provide mechanical support.

2.

To carry efficiently electric, magnetic flux.

3. To ensure the perfect link between the core and rotor.

STATOR WINDING

Each conductor must be capable of carrying rated current without over heating.

The stator winding consists of two layers made up of individual bars. Windings for

the stators are made of copper strips wound with insulated tape which is impregnated

with varnish, dried under vacuum and hot pressed to form a solid insulation bar.

These bars are then placed in the stator slots and held in with wedges to form the end

turns. These end turns are rigidly placed and packed with blocks of insulation material

to withstand heavy pressure.

The stator bar consists of hollow (in case of 500 MW generators) solid strands

distributed over the entire bar cross-section, so that good heat dissipation is ensured.

In the straight slot portion the strands are transposed by 540 degrees. The

transposition provides for mutual neutralization of the voltage induced in the

individual strands due to slot cross field and end winding flux leakage and ensure that

minimum circulating current exists. The current flowing through the conductors is

thus uniformly distributed over the entire cross section so that the current dependent

losses will be reduced.

The alternate arrangement of one hollow strand and two solid strands ensures

optimum heat removal capacity and minimum losses. The electrical connection

between top and bottom bars is made by connecting sleeve.

Class F insulation is used.

The no. of layer of insulation depends on machine voltage. The bars are brought under

vacuum and impregnated with epoxy resin, which has very good penetration property

due to low viscosity. After impregnation bars are subjected to pressure with nitrogen

being used as pressurizing medium (VPI process). The impregnated bars are formed

to the required shape on moulds and cured in an oven at high temperature to minimize

the corona discharge between the insulation and slot wall a final coat of

semiconducting varnish is applied to the surface of all bars within the slot range. Inaddition all bars are provided with an end corona protection to control the electric

field at the transition from the slot to end winding. The bars consist of a large no. of

separately insulated strands which are transposed to reduce the skin effect.


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INSULATION OF BARS

A. Vacuum pressed impregnated micaclastic high voltage insulation:-

The voltage insulation is provided according to the proven resin poor mice base of

thermo setting epoxy system. Several half overlapped continuous layer of resin poor

mica tape are applied over the bars. The number of layers or thickness of insulation

depends on the machine voltage. To minimize the effect of radial forces windingshold and insulated rings are used to support the overhang.

B. Corona Protection:-

To prevent the potential difference and possible corona discharge between the slot

wall and the insulation, the section of bars are provided with outer corona protection.

The protection consists of polyester fluce tape impregnated in epoxy resin with carbon

and graphite as fillers. At the transition from the slot to the end winding portion of the

stator bars a semiconductor tape is impregnated.


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C. Resistance Temperature Detector:-

The stator slots are provided with platinum resistant thermometer to record and watch

the temperature of stator core and tooth region and between the coil sides of machine

in operation. All AC machines rated for more than 5 MVA or with armature core

longer, the machine is to be provided with at least 6 resistance thermometers. The

thermometer should be fixed in the slot but outside the coil insulation. When thewinding has more than one coil side per slot, the thermometer is to be placed between

the insulated coil sides. The length of resistance thermometer depends upon the length

of armature. The leads from the detector are brought out and connected to the terminal

board for connection onto temperature meter or relays. Operation of RTD is based on

the prime factor that the electric resistance of metallic conductor varies linearly with

temperature

END COVERS:-

The end covers are made up of fabricated steel or aluminum castings. They are

employed with guide vans on inner side for ensuring uniform distribution of air or

gas.


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IV. EXCITATION SYSTEM:-

EXCITER:-

EXCITER ROTOR

The basic use of given exciter system is to produce necessary DC for

turbo generator system. Principal behind this is that PMG is mounted on the

common shaft which generates electricity and that is fed to yoke of main

exciter. This exciter generates electricity and this is of AC in nature. This ACis that converted into DC and is that fed to turbo generator via C/C bolt. For

rectifying purpose we have RC block and diode circuit. The most beautiful

feature is of this type of exciter is that is automatically divides the magnitude

of current to be circulated in rotor circuit. This happens with the help of AVR

regulator which means automatic voltage regulator. A feedback path is given

to this system which compares theoretical value to predetermine and than it

sends the current to rotor as per requirement.


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The brushless exciter mainly consists of:-

1. rectifier wheels

2. three phase main exciter

3. three phase pilot exciter

4.

Metering and supervisory equipment.

The brushes exciter is an AC exciter with rotating armature and

stationery field. The armature is connected to rotating rectifier bridges forrectifying AC voltage induced to armature to DC voltage. The pilot exciter is a

PMG (permanent magnet generator). The PMG is also an AC machine with

stationery armature and rotating field. When the generator rotates at the rated

speed, the PMG generates 220 V at 50 hertz to provide power supply to

automatic voltage regulator.

A common shaft carries the rectifier wheels the rotor of main exciter

and the permanent magnet rotor of pilot exciter. The shaft is rigidly coupled to

generator rotor and exciter rotors are than supported on these bearings.

V. BAY IV (SMALL AND MISCELLANEOUS COMPONENTS)

Facilities available in the various sections are as follows:-

MACHINE SECTION:-

The machine section of Bay-4 is equipped with small and medium sizeCNC & conventional machine tools like centre lathes, milling, radial drilling,


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cylindrical grinding, slotting, copy turning lathe, internal grinding and surface

grinding machines. Small-size and miscellaneous components for Turbo-

generators, Hydro generators and Motors are machined in this section.

POLE COIL SECTION

COILING SECTION

This section is equipped with baking oven , pneumatic shearingmachines , semi-automatic winding machines , pole straightening installations

, electric furnace for bright annealing of copper , tinning installation and

hydraulic press (800 Ton capacity ) for manufacturing Pole Coils of DC

motors , AC synchronous motors and hydro generators . Pole assembly is also

carried out in this section.

Manufacturing of coils (hydro generators) taken in this section.

German copper coils are initially in the form of rolls. These rolls are then

undergoes following processes to change into copper coils which are then

mounted with poles-

1. ANNEALING PROCESS:-

This is the process of hardening or softening any metal.

Initially copper rolls are hard & if it undergoes annealing then it may

breaks so firstly to make it soft so that it can easily change to winding.

This process is carried out in the annealing furnace.


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WINDING PROCESS:-

This process undergo following steps:-

Take out the softened copper rolls for pole coil winding. Winding is done with the help of change plate & winding template so

ensure major working dimensions of change plate & winding template

with respect to tool drawing.

Adjust & set the winding machine as per the product standards using

gear rack, change plate & winding template. Ensure parallelity of

winding template with respect to machine platform. Maintain height of

winding template with platform. Wind the coil in anticlockwise

direction.

NOTE:-

The joint in the copper coil shall be located in the straight part of

longer side.

If required heating by gas torch of copper profile at corner zone at

temperature between 100-150 degree centigrade is allowed. This is

to make easier bending.

2. BRAZING:-

Braze the joint with brazing alloy Ag40Cd.

Remove the coil with machine with 2 to 3 turns extra than the actual

number of turns for preparation of end-half turns.

3. Carry out bright annealing of the coil. Take out the coil from the oven

after annealing.

4.

PRESSING:-

Pressing of coil is done by hydraulic pressure of 800 tons.

This process is carried out in order to remove wrinkles from the coil.

This process is carried out after every process. In this process, set the

coil on the mandrel for pressing then slide the coil under press and

press the coil.

Take out the coil from press.

5.

FIXING:-


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Fix the accessory on the stretching machine.

Put the coil on the stretching machine& pull the coil to the drawing

dimensions.

Dress the conductors along periphery & take out the coil.

Check window dimensions as per drawing.

6. SEPARATION:-

Remove the buckling of each coil manually.

Grind the bulging of the copper at place of binding (inner side) with

pneumatic grinder.

Check the thickness of the profiled copper with the gauge. Grinding

shall be uniform & of smooth finish.

Round of sharp edges.

** Again press the coil as in pt.5 & take out the coil from the press.

7. PICKLING:-

Send the coil for pickling to block 4 & check the quality of pickling.

Press the coil again after pickling then remove pressure and take out

the coil.

8. Prepare end half turn as per drawing with template.

9. Braze item 2 & 3 corresponding to the variant with end half turn with

brazing alloy

Ag 40 Cd.

Remove extra material, clean and check with gauge.

Adjust the end half turn with top & bottom turn of coil braze the joint.

Remove extra material and check thickness of the gauge.

Check the distance from center axis of pole coil as per drawing.

10. FINISHING:-

Hang the coil on stand and separate out turns


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Remove black spots, burrs the sharp edges and clean the coil turns with

cotton dipped in thinner.

Press the coil again and check the height of the coil under press to

check dimensions as per drawing.

11.Take out the coil from the press and send for insulation.

12. INSULATION:-

Hang the coil on stand and separate out the turn.

Clean each turn with cotton dipped in thinner.

Apply Epoxy varnish on both sides of each turn with brush uniformly

all over the leaving top & bottom turn.

Cut strips of Nomax paper as per contour of coil with technologicalallowance 3 to 5 mm on either side.

Stick two layers of Nomax strips between each turn.

Coat varnish layer between two layers of Nomax also.

Let the excess varnish to flow out some time

13. BAKING AND PRESSING OF COIL:-

Place the coil on mandrel putting technological washer at top & bottom

of the coil.

Heat the coil by DC up to 100 +/-5o C , and maintain for 30 to 40

minutes.

Switch off the supply and elongate the coil and tight the pressing

blocks from sides.

Start heating coil again and raise temperature gradually in steps up to

130 +/- 5o C , with in 10 +/- 10 minutes.

Apply 110 tones pressure and maintain for 20 to 30 minutes. Then after

every half an hour, increases the pressure and temperature according to

product requirement.

Stop heating and then allow cooling the coil under pressure below 50oC, and taking out the coil from the press.

14.CLEANING AND DRYING:-

Clean outer and inner surface of projected insulation by means of shop

made scrubber.

Flow dry compressed air after cleaning.

Check height and window dimensions as per drawing.

Check no gap between the turns.


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Test the coil from inter turn test at 116 volts AC at a pressure of 480

tons in 5 minutes.

15.Coat the coil with two layers of epoxy red gel.

TURBO ROTOR COIL SECTION:-

This section is equipped with copper straightening and cutting

machines, edge bending machines, installation for forming and brazing, 10-

block hydraulic press and installation for insulation filling. Rotor coils for

water cooled generators (210 /235 MW) are manufactured in this section.

IMPREGNATION SECTION:-

This section is equipped with electric drying ovens, Air drying booths,

Bath for armature / rotor impregnation. Rotors / armatures of AC and DC

motors are impregnated in this section.

BABBITING SECTION:-

This section is equipped with alkaline degreasing baths, hot and cold

rinsing baths, pickling baths, tinning bath, and electric furnaces and centrifugal

Shot Blasting

babbitting machines, Babbitting of bearing liners for Turbo generators,

Turbines, Hydro generators, AC motors and DC motors is carried out in this

section.


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VI. TEST STANDS:-

Turbo-generators Test Bed -The Test Bed for Turbo-generators and Heavy

motors is equipped with one no. 6 MW drive motor and a test pit for carrying

out testing of Turbo-generators and Heavy motors. Open circuit, short circuit,temperature rise, hydraulic and hydrogen leakage test etc., are carried out here

for Turbo-generators. AC motors up to 11 MVA capacity and DC machines up

to 5000 amps and 850 volt can also be tested. Two DC drive motors of 2200

KW and one of 1500 KW are available for type testing of motors. Data

logging equipment is also available.

VII. LARGE SIZE TURBO GENERATOR TEST STAND (LSTG):-

It is equipped with a 12 MW drive motor and two number test pits. Open

circuit ,short circuit , sudden short circuit , temperature rise , hydraulic &hydrogen leakage tests are carried out here Large size Turbo-generators. This

test bed can presently test Tgs of unit capacity up to 500 MW. With certain

addition in facilities (Higher capacity Drive motor and EOT cranes and

modification in controls and auxiliary systems), Turbo-generators of unit size

up to1000 MW can be tested.

HELIUM LEAK TEST

PURPOSE

To check any leakage of gas from stator and rotor as if there is any leakage of

gas used for cooling such as hydrogen then it may cause an explosion.

VIII. Testing of stator frame involves two types of testing:

HYDRAULIC TESTING AND PNEUMATIC TESTING

Hydraulic testing involves in empty stator frame with attached end shields and

terminal box is subjected to a hydraulic test at 10 bar to ensure that it will be

capable of withstanding maximum explosion pressure.

The pneumatic testing involves filling of hydrogen in the sealed stator frame

and then soap water is used to check the leakage of welding.


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4. CONCLUSION

The Vocational training at BHEL Hardwar helped me in improving my practical

knowledge and awareness regarding Turbo Generator to a large extent.

Here I came to know about the technologies and material used in manufacturing ofturbo generators. Besides this, I also visualized the parts involved or equipments used

in the power generation.

Here I learnt about how the electrical equipments are being manufactured and how

they tackle the various problems under different circumstances. At least I could say

that the training at BHEL Hardwar is great experience for me and it really helped me

in making or developing my knowledge about turbo generator and other equipment

used in power generation.

5.REFERENCES

1. Material provided by the training Incharge.

2. Internet

bhel - training report punnet

Documents