1

Barh Super Thermal Power Plant

A

PRACTRICAL TRAINING REPORT

Submitted for the Partial Fulfilment of the Requirement of the

Degree

BACHELOR OF TECHNOLOGY

In

ELECTRICAL ENGINEERING

Submitted to: Submitted By:

Prof Kusum Agrawal Jay Pratap

(Head-EE) (IV B. Tech., VII Sem.)

Department of Electrical Engineering

Jodhpur Institute of Engineering & Technology,

JIET Group of Institutions, Jodhpur.

Rajasthan Technical University, Kota (Raj.)

2016-17

2

CONTENT

Chapter Page No.

1. National Thermal Power Plant 1-8

1.1 Introduction 1

1.2 Journey of NTPC 2

1.3 Installed Capacity 3

1.3.1 Coal Based Power Stations 4

1.3.1.1 Coal Based Joint Ventures/Subsidiaries 5

1.3.2 Gas Based Power Station 5

1.3.3 Hydro Based Power Projects 6

1.3.4 Renewable Energy 7

1.3.4.1 Solar Energy 7

1.3.4.2 Hydro Energy 7

1.3.4.3 Geothermal Energy 8

2. Barh Super Thermal Power Plant 9-11

2.1 Introduction 9

2.2 Site Selection Criteria 9

2.3 Project Cost 10

2.4 Beneficiary State 10

2.5 Design Features 11

3. Coal Handling Plant 12-15

3.1 Introduction 12

3.2 Wagon Unloading System 13

3.2.1 Wagon Tripler 13

3.2.2 Crushing System 13

3.2.3 Crusher House\ 13

3.3 Construction & Operation 14

3.4 Conveying System 14

4. Ash Handling Plant 16-17

4.1 Introduction 16

4.2 Fuel and ash plant 16

4.3 Air & Gas Plant 16

4.4 Ash Disposal & Dust Collection Plant 17

4.5 Utilisation 17

3

5. Water Treatment Plant 18-20

3.1 Introduction 18

3.2 Process of Purification 18

3.3 De mineralizing Plant 19

6. Pulveriser Plant 21-23

6.1 Introduction 21 6.2 Fundamental Requirement of a Pulveriser 21

6.3 Raw Coal Feeders 21 4.3.1 Rotary Volumetric Feeder 21

6.4 Pulverisers 22

6.5 Bowl Mill 22

6.6 Factors Affecting Mill Performance 23

7. Boiler 24-25

7.1 Introduction 24

7.2 Function of boiler drum 24

7.3 Steam Separator 24

7.4 Super Heater 24

7.5 Re-Heater 25

7.6 Economizer 25

7.6.1 Economiser Failure 25

7.7 Furnace 25

8. Turbine 26-27

8.1 Introduction 26

8.2 Working Principle of the Steam Turbine 26

8.3 Turbine Type 26

8.3.1 Impulse Turbine 26

8.3.2 Reaction Turbine 27

8.4 Classification of the Steam Turbine 27

4

9. Generator 28-33

9.1 Introduction 28

9.2 Parts of Generator 28

9.3 Starting of Generator 30

9.4 Shutting Down of Generator 31

9.5 Excitation System 31

9.6 Types of Excitation 32

9.7 Turbo Generator Specification 32

10. Switchyard 34-38

10.1 Introduction 34

10.1.1 400KV Switchyard 34

10.1.2 132KV Switchyard 34

10.2 Components of Switchyard 35

11. Transformer 39-44

11.1 Introduction 39

11.2 Classification 41

11.3 Generating Transformer 41

11.4 Inter Connecting Transformer 42

11.5 Station transformer 43

11.6 Unit Transformer 43

11.7 Miscellaneous Service transformer 44

CONCLUSION 45

REFERENCES 46

5

TABLE LIST

Table No Table Name Page No

1.1 Installed Capacity Overview 3

1.2 Regional Spread of Generating Facilities 3

1.3 Coal Based power stations 4

1.4 Coal Based Joint Ventures/Subsidiaries 5

1.5 Gas /Liq. Fuel Based Power Station 5

1.6 Power Plants with Joint Ventures 6

1.7 Hydro Based Power Plan 7

1.8 Projects Commissioned (360 MW) 8

6

FIGURE LIST

Figure No Figure Name Page No

1.1 Inside a Hydropower Plant 6

1.2 Geothermal Power Plant 8

2.1 Barh Super Thermal Power Plant 9

3.1 Processing of Coal Handling Plant 12

3.2 Coal Crushing System 13

5.1 Flow dig of Process of Purification 18

8.1 Multi Stage steam Turbine Generator 26

9.1 Cross Section View Generator 30

10.1 Component of Switchyard 35

10.2 Connection of current transformer 36

11.1 Cross Section View Transformer 39

11.2 Generator transformer 42

7

CHAPTER 1

NATIONAL THERMAL POWER PLANT

1.1 Introduction

NTPC, the largest power company in India was setup in 1975 to accelerate power

development in the country. It is world’s largest and most efficient power generation

companies. In Forbes list of 2000 Largest Companies for the year 2007, NTPC occupies

411th place.

NTPC has installed capacities of 47,228MW. It has 18 coal based power station (35,085

MW), 7 gas based power station (4,017 MW), and 9 power station in joint Ventures (6,966

MW). 1 hydro based power station (800 MW). And 9 Renewable energy projects (360

MW). The company has power generating facilities in all major regions of the country. It

plans to be a 75,000MW company by 2017

NTPC has gone beyond the thermal power generation. It has diversified into hydro

power, coal mining , power equipment manufacturing ,oil and gas exploration, power

trading & distridution. NTPC is now in the entire power value chain and is poised to

become an integrated power Major. NTPC share on 31mar 2008 in the total installed

4000

6000

100001100011000

1200013000

1400015000

170001750018000

225002250023500

2200021000

2400023000

28000

Series 1, 30000

0

5000

10000

15000

20000

25000

30000

35000

M W

Growth of NTPC Installed Capacity

8

capacity of the country was 19.1% and it contributed 28.50% of total power generation of

the country during 2007-08. NTPC has set new benchmarks for power industry both in the

area of power construction and operation.

With its experience and expertise in the power section. NTPC is extending consultancy

services to various organisations in the power business. It provide consultancy in the area

of power plant construction and power generation companies in India and abroad. IN

November 2004, NTPC came out with its initial public offering (IPO) consisting of 5.25%

as fresh issue and 5.25% as offer for sale by government of India. NTPC thus became a

listed company with government holding 89.5% of the equity share capital and rest held by

institutional investors and public. The issue was a resounding success. NTPC is among the

largest five companies in India in term of market capitalization.

Recognising its excellent performance and vast potential, government of the India has

identified NTPC as one of the jewels of public sector ‘Navratnas’-a potential global glant.

Inspired by its glorious past and vibrant present, NTPC is well on its way to realise its

vision of being “A world class integrated power major, powering India’s growth, with

increasing global presence”.

1.2 Journey of NTPC

1975:-NTPC was set up in 1975 with 100% ownership by the government of India.

In the last 30 year, NTPC has grown into the largest power utility in India

1997:- in 1997, government of India granted NTPC status of ‘Navratna’ being one

of the nine jewels of India.

2004:-NTPC become a listed company with majority government ownership of

89.5%, NTPC become 3rd largest by market capitalisation of listed companies

2005:-the company rechristened as NTPC limited in the line with its changing

business portfolio and transform itself from a thermal power utility to an integrated

power utility.

2008:-national thermal power corporation is largest power Generation Company in

India. Forbes global 2000 for 2008 ranked it 411th in the world.

2009:- national thermal power corporation is largest power Generation Company in

India. Forbes global 2000 for 2008 ranked it 317th in the world.

2012:-NTPC has also set up a plan to achieve a target of 50,000MW generation

capacity.

9

2017:-NTPC has embarked on plans to become a 75,000MW company by 2017

1.3 Installed Capacity

Present installed capacity of NTPC is 47,228 MW (including 6,966 MW through

JVs/Subsidiaries) comprising of 44 NTPC Stations (18 Coal based stations, 7 combined

cycle gas/liquid fuel based stations, 1 Hydro based station), 9 Joint Venture stations (8 coal

based and one gas based) and 9 renewable energy projects

Table-1.1 Installed Capacity Overview

No of Plants Capacity MW

NTPC Owned

Coal 18 35,085

Gas /Liquid full 7 4,017

Hydro 1 800

Renewable energy

projects (Solar PV)

9 360

TOTAL 35 40,012

Owned By jvs

Coal & Gas 9 6,966

TOTAL 44 47,228

Table-1.2 Regional Spread of Generating Facilities

Region Coal Gas/liquid fuel Renewable Total

Northern 9,015 2,344 35 11,394

Western 12,000 1,313 50 13,363

Southern 4,600 360 260 5,220

Eastern 9,470 - 10 9,480

Island - - 5 5

Hydro - - - 800

JVs 4,999 1,967 - 6,966

Total 40,084 5,984 360 47,228

10

1.3.1 Coal Based Power Stations

With 18 coal based power stations, NTPC is the largest thermal power generating company

in the country. The company has a coal based installed capacity of 35,085 MW.

Table-1.3 Coal Based power stations

Sr.

No.

Coal based (Owned by

NTPC)

State Commissioned

Capacity

(MW)

1 Singrauli Uttar Pradesh 2,000

2 Korba Chhattisgarh 2,600

3 Ramagundam Telangana 2,600

4 Farakka West Bengal 2,100

5 Vindhyachal Madhya Pradesh 4,760

6 Rihand Uttar Pradesh 3,000

7 Kahalgaon Bihar 2,340

8 Dadri Uttar Pradesh 1,820

9 Talcher kanitha Orissa 3,000

10 Feroze Gandhi Unchahar Uttar Pradesh 1,050

11 Talcher Thermal Orissa 460

12 Simhadri Andhra Pradesh 2,000

13 Tanda Utter Pradesh 440

14 Badarpur Delhi 705

15 Sipat Chhattisgarh 2,980

16 Mauda Maharashta 1,660

17 Barh Bihar 1,320

18 Bongaigaon Assam 250

Total (Coal) 35,085

1.3.1.1 Coal Based Joint Ventures/Subsidiaries

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Table-1.4 Coal Based Joint Ventures/Subsidiaries

Sr. No. Coal Based (Owned by

JVs/Subsidiaries)

State Commissioned (MW)

1 Durgapur West Bengal 120

2 Rourkela Orissa 120

3 Bhilai Chhattisgarh 574

4 Kanti Bihar 610

5 IGSTPP, Jhajjar Harayana 1500

6 Vallur Tamil Nadu 1500

7 Nabinagar-BRBCL Bihar 250

8 PUVNL(Patratu) Jharkhand 325

Total 4,999

1.3.2 Gas Based Power Stations

The details of NTPC gas based power stations is as follows

Table-1.5 Gas /Liq. Fuel Based Power Station

Sr. No. Gas based

(Owned by NTPC)

State Commissioned

Capacity (MW)

1 Anta Rajasthan 419.33

2 Auraiya Uttar Pradesh 663.33

3 Kawas Gujarat 656.20

4 Dadri Uttar Pradesh 829.78

5 Jhanor-Gandhar Gujarat 657.39

6 Rajiv Gandhi CCPP

Kayamkulam

Kerala 359.58

7 Faridabad Haryana 431.59

Total 4,017.23

Table-1.6 Power Plants with Joint Ventures

12

Sr.

No.

Coal based

(Owned by

NTPC)

State Commissioned

Capacity (MW)

1 RCPPL Maharashtra 1967.08

TOTAL 1,967.08

1.3.3 Hydro Based Power Projects

Fig:-1.1 Inside a Hydropower Plant

NTPC has increased thrust on hydro development for a balanced portfolio for long term

sustainability. The first step in this direction was taken by initiating investment in Koldam

Hydro Electric Power Project located on Satluj River in Bilaspur district of Himachal

Pradesh. Other hydro project under construction is Tapovan Vishnugad. On all these

projects construction activities are in full swing.

Table -1.7 Hydro Based Power Plant

SR.

No.

Hydro Based State Approved

Capacity

Commission

Capacity (MW)

1 Koldam(HEPP) Himachal

Pradesh

800 800

2 Tapovan

Vishnugad (HEPP)

Uttrakhand 520 -

3 Singrauli CW

Discharge(Small

Hydro)

Uttar Pradesh 8 -

13

4 Lata Tapovan Uttrakhand 171 -

5 Rammam West Bengal 120 -

Total 1,519 800

1.3.4 Renewable Energy

The future lies with renewable energy. Renewable energy technologies provide clean and

green sources of electricity. With their abundance supply, they form the backbone for

India’s energy security and ‘energy independence’ as envisaged by 2020. We aim to

transform NTPC into the country's largest green power producer in the coming years. Green

power is national power.

1.3.4.1 Solar Energy:

Table 1.8 -Projects Commissioned (360 MW)

Sr. No. Project State Capacity (MW)

1 Dadri Solar PV Uttar Pradesh 5

2 Port blair Solar PV Andaman & Nicobar

Island

5

3 Ramagundam Solar PV

(Phase -I)

Telangana 10

4 Talcher Kaniha Solar PV Odisha 10

5 Faridabad Solar PV Harayana 5

6 Unchahar Solar PV Uttar Pradesh 10

7 Rajgarh Solar PV Bihar 50

8 Singrauli Solar PV Uttar Pradesh 15

9 Ananthapuram Solar PV Andhra Pradesh 250

Total 360

1.3.4.2 Hydro Energy:

Projects under Execution (8 MW)

14

8 MW hydro energy based project at NTPC-Singrauli in Uttar Pradesh.

1.3.4.3 Geothermal Energy:

Fig1.2:-Geothermal Power Plant

Tattapani Geothermal Project in Chhattisgarh: MoU Signed with Govt. of Chhattisgarh.

15

CHAPTER 2

BARH SUPER THERMAL POWER PLANT

2.1 Introduction

Barh Super Thermal Power Plant (BSTPP) or NTPC Barh is located in Barh ( Bihar) .NTPC

Barh is located nearly four kilometres east of the Barh subdivision on National Highway31

in Patna district. The project has been named a mega power project, and is owned by Indian

energy company National Thermal Power Corporation.

Fig:-2.1 Barh Super Thermal Power Plant

The Barh super thermal power plants consist of two stages and total generation unit is five.

In the 1st stage 1,980MW (3x660MW) built by Russian firm Technopromexport (TPE) and

2nd stage 1,320MW (2x660MW) extension is being built by BHEL.

The main power plant and the township is spread over an area of 1,186 acres. The legal

possession of 1,186 acres of land has been acquired for setting up the main

Power plant and its township which includes 12 villages.

The PM, Atal Bihari Vajpayee, had laid the foundation stone of the main plant of stage1

of NTPC

Barh on March 6, 1999. The formal inauguration of its site office and laying of the

foundation stone of the training centre at the plant site was done in September

2003. Former Union power minister Sushil Kumar Shinde had inaugurated the main plant

house of stage2 of NTPC Barh on May 29, 2006.

2.2 Site Selection Criteria

1 Background

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Barh super thermal power plant, stage 1and stage 2 is set by NTPC is located in Barh in

Patna district of Bihar state. The total generating unit is 660MW each. In stage 1there are

3 unites and in stage 2 there are 2 unites. The total capacity of the project will be 3300 MW

(3X660 MW+2X660 MW).

2 Location

The project site is located about 3kms east of Barh town in Patna district in the state of

Bihar, having a latitude and longitude of 25 deg 28' N and 85deg 45' E respectively. The

plant and township are located between NH-31 and railway line. The ash disposal area is

located in the south of the railway line

3 Land Requirement

Approximately 1200 acres of land has been identified between NH-1 and railway lines for

the plant area, switchyard, green belt, labour colony, ash based units and township.

Approximately 1750 acres of land has been identified for the ash disposal area in the south

of railway line

4 Water Requirement

The project site is located near the river Ganga. The makeup water requirement for the

project is proposed to be drawn from river Ganga.

5 Coal requirement

Hazaribagh coal mines. Coal requirement for the project in estimated as 10 million

tones/annum considering a GCV of 3350 kcal/kg and 80% PLF.

2.3 Project Cost

The total production of the plant is 3,300MW at the cost of Rs 26,000 crores. In the 1st stage

(3x660MW) total approved cost is Rs 8,692.97 crores. And the 2nd stage (2x660MW) total

approved cost is Rs 7,688.12 crores

2.4 Beneficiary state

The states & UTs of Northern & Western regions and state of Bihar

2.5 Design Features

The satisfactory design consists of the flowing steps.

17

1. Estimation of cost.

2. Selection of site.

3. Capacity of Power Station.

4. Selection of Boiler & Turbine.

5. Selection of Condensing Unit.

6. Selection of Electrical Generator.

7. Selection of Cooling System.

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CHAPTER 3

COAL HANDLING PLANT

3.1 Introduction

In the thermal power plant required large amount coal so it required to store. In the thermal

power plant the coal is store in the coal handling plant. The main purpose of coal handing

plant to store in huge amount of coal for continuous generation of power in thermal power

plant.

The coal is brought to the NTPC, Barh through rails. The main coal sources for NTPC,

Barh are hazaribagh coal mine. The Coal transported to the project site through Indian

railways system for a distance of approximately 250kms via shorter route Coal requirement

for the project in estimated as 10 million tones/annum considering a GCV of 3350kcal/kg

and 80% PLF. The coal is firstly unloaded from wagon by wagon triplers then crushed by

crushers and magnetic pulley and pulverized to be transformed to the boiler. The whole

transportation of coal is through conveyor belt operated by 3-Ø Induction motor.

Fig 3.1:-Processing of Coal Handling Plant

The coal handling plant can broadly be divided into three sections:-

1) Wagon Unloading System.

2) Crushing System.

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3) Conveying System.

3.2 Wagon Unloading System

3.2.1 Wagon Tripler

Unloads the coal from wagon to hopper to hopper with the help of wagon Tripler. The

Hopper, which is made of Iron, is in the form of net so that coal pieces of only equal to and

less than 200 mm. size pass through it. The bigger ones are broken by the workers with the

help of hammers. From the hopper coal pieces fall on the vibrator. It is a mechanical system

having two rollers each at its ends.

The four rollers place themselves respectively behind the first and the last pair of wheels

of the wagon. When the motor operates the rollers roll in forward direction moving the

wagon towards the “Wagon Table”. On the Wagon table a limit is specified in which

wagon to be has kept otherwise the triple would not be achieved.

3.2.2 Crushing System

Fig 3.2:- Coal Crushing System

3.2.3 Crusher House

It consists of crushers which are used to crush the coal to 20 mm. size. There are mainly

two type of crushers working in STPP, Barh:-

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1. Primary Crushers i.e. i) Rail crushers or ii) Rotary breaker.

2. Secondary Crushers. I.e. Ring granulators.

1 Primary Crushers

Primary crushers are provided in only CHP stage 3 system, which breaking of coal in CHO

Stage 1 & Stage 2 system is done at wagon tripler hopper jail up to the size (-) 250 mm.

2 Secondary Crusher

Basically there are four ways to reduce material size: impact attrition, Shearing and

Compression. Most of the crushers employ a combination of three crushing methods. Ring

granulators crush by compressing accompanied by impact and shearing. The unique feature

of this granulator is the minimum power required for tone for this type of material to be

crushed compared to that of other type of crushers.

3.3 Construction & Operation

Secondary crushers are ring type granulators crushing at the rate of 550 TPH / 750 TPH for

input size of 250 mm. and output size of 20 mm. The crusher is coupled with motor and

gearbox by fluid coupling.

Main parts of granulator like break plates, cages, crushing rings and other internal parts are

made of tough manganese (Mn) steel.

The rotor consists of four rows of crushing rings each set having 20 Nos. of toothed rings

and 18 Nos. of plain rings. In CHP Stage 1 & 2 having 64 Nos. of ring hammers. These

rows are hung on a pair of suspension shaft mounted on rotor discs.Crushers of this type

employ the centrifugal force of swinging rings stroking the coal to produce the crushing

action. The coal is admitted at the top and the rings stroke the coal downward. The coal

discharges through grating at the bottom.

3.4 Conveying System

Belt are used to convey coal from coal handling plant to furnace

3.4.1 Specification

Belt 1400mm

21

Speed 2.2m/s

Total Install Power 360kw

Capacity 1350/750 ton/hr.

No of Conveyor 38

22

CHAPTER 4

ASH HANDLING PLANT

4.1 introduction

A natural result from the burning of fossil fuels, particularly coal, is the emission of flyash.

Ash is mineral matter present in the fuel. For a pulverized coal unit, 60-80% of ash leaves

with the flue gas

This plant can be divided into 3 sub plants as follows:-

1) Fuel and Ash Plant.

2) Air and Gas Plant.

3) Ash Disposal and & Dust Collection Plant.

4.2 Fuel and ash plant

Coal is used as combustion material in STPP, Barh. In order to get an efficient utilization

of coal mills. The Pulverization also increases the overall efficiency and flexibility of

boilers. However for light up and with stand static load, oil burners are also used. Ash

produced as the result of combustion of coal is connected and removed by ash handling

plant. Ash Handling Plant at STPP, Barh consists of specially designed bottom ash and fly

ash in electro static precipitator economizer and air pre-heaters hoppers.

4.3 Air & Gas Plant

Air from atmosphere is supplied to combustion chamber of boiler through the action of

forced draft fan. In STPP, Barh there are two FD fans and three ID fans available for draft

system per unit. The air before being supplied to the boiler passes through preheater where

the flue gases heat it. The pre heating of primary air causes improved and intensified

combustion of coal.

The flue gases formed due to combustion of coal first passes round the boiler tubes and

then it passes through the super heater and then through economizer. In re-heater the

temperature of the steam (CRH) coming from the HP turbines heated with increasing the

number of steps of re-heater the efficiency of cycle also increases. In economizer the heat

23

of flue gases raises the temperature of feed water. Finally the flue gases after passing

through the Electro-Static Precipitator is exhausted through chimney.

4.4 Ash Disposal & Dust Collection Plant

STPP, Barh has dry bottom furnace. Ash Handling Plant consists of especially designed

bottom and fly ash system for two path boiler. The system for both units is identical and

following description is applied to both the units the water compounded bottom ash hopper

receives the bottom ash from the furnace from where it is stores and discharged through

the clinker grinder. Two slurry pumps are provided which is common to both units & used

to make slurry and further transportation to ash dyke through pipe line.

Dry free fly ash is collected in two number of 31 fly ash hoppers which are handled by two

independent fly ash system. The ash is removed from fly ash hoppers in dry state is carried

to the collecting equipment where it is mixed with water and resulting slurry sump is

discharged

4.5 Utilisation

Utilisation of coal-ash is always practise than its disposal. There are various methods of

utilisation of coal-ash along with established engineering technologies some of them are

mentioned below:

Manufacturing of building materials.

Making of concrete.

Manufacturing of pozzuolana cement.

Road construction etc.

24

CHAPTER 5

WATER TREATMENT PLANT

5.1 Introduction

All natural sources of water contain impurities as well as dissolved gasses. The amount of

these impurities depends on type of water source and location.

The main impurities are:-

1. Suspended (Macro Size)-sand, dirt, silt, this contributes turbidity to raw water

2. Colloidal-micro size particles (1-100mm)

3. Dissolved form –Alkaline salt and neutral salts organic matter,

Alkaline salts are mainly bicarbonates rarely carbonates and hydrate of calcium,

magnesium and sodium

Neutral salts are sulphate, chloride, nitrates of calcium, magnesium and sodium

5.2 Process of purification

Fig 5.1:-Flow dig of Process of Purification

1. The raw water is taken from cooling water plant & reservoir.

2. The chemicals are added such as (ALUM+LIME/PAC & CL2) and remove impurities

in the water

3. This water is fed to flash mixer, which consist of a 900 rotated path for purpose of

mixing chemicals, which are added to water. In BSTPP natural mixing is used.

25

4. Then this water is fed to cloriflocculatar tank which consist of cylindrical shape and

two stage water is fed in internal stage & from bottom it comes to outer stage &all

impurities form flock and settle down in inner portion so it is said flocculated zone. The

pure water comes to outer portion in which cl2 is dissolved so it is said clarifier zone.

The water from clariflacculatar tank is fed to filter bed in BSTPP gravity bed are used

to remove impurities.

5. Then the water is fed to sump which is a big tank with no portion open. It is to store

pure water.

6. With help of pumps the water is fed to place of utilization. Various pumps are

A. Potable water pump: for supplying drinking water.

B. Back wash water pump: for reversing cycle of water for washing filter bed.

C. Filtered water pump: to supply water to make steam.

D. Filter water treatment pump: To fed water to D.M plant

5.3 De mineralizing plant

Water mainly in plant is used for cooling purpose. In this process water must be free from

all dissolved impurities.

This plant consist of two stream each stream with activated carbon filter , weak acid ,carbon

exchanger and mixed bed exchanger .The filter water to DM water plant through 250 dia

header from where a header top off has been taken off to softening plant. Two filtered water

booster pumps are provided on filtered water line for meeting the pressure requirement in

D.M plant.

Sodium sulphate solution of required is dosed into different filtered water by mean of

dosing pump to neutralize cl 2 prior to activated carbon filter. When water passes on

activated carbon filter will remove the residual chlorine from water provision is made for

back washing the activated carbon filter enter works acid carbon unit the deletion water

enter the weak base anion exchanger unit water then enter degasified unit where free co 2

is scrubbed out of water by upward counter flow of low pressure air flow through degasified

lower and degassed water is pumped to strong base exchanger.

CATION EXCHANGER.

R-H + Ca+2 R2-Ca + H+

26

ANION EXCHANGER

R-OH + Cl- R-Cl + OH-

H+ + OH - H20

Arrangement for designing ammonia solution into de-mineralized water after mixed bed

unit has been provided for ph correction before water is taken into be condensate transfer

pump the DM water to unit condenser as make up the softening plant is a designed to

produce 100 cubic m/Hr. of softened water per stream.

27

CHAPTER 6

PULVERISER PLANT

6.1 Introduction

Of the three commercial fuels- coal, petroleum, natural gas, and coal is the basic fuel used

in the boiler for the power generation due to its distribution and availability. Though coal

can be burnt in a boiler in many ways such a hand firing, stoking firing, pulverised coal

firing, cyclone furnace etc, and pulverised coal firing is favoured over other methods of

burning coal because of many advantages. About 80% of the coals for the generation of

electricity are burnt in the pulverised form.

6.2 Fundamental Requirement Of A Pulverised Plant

Supply of coal in the pulverised form to the boiler furnace can be accomplished by using

different type of equipment and systems. The use of a particular type of equipment is

decided on the type of coal used, boiler requirements, user preference etc.

1. Raw coal feeding

2. Drying

3. Grinding and circulating

4. Classifying

5. Transporting

6.3 Raw Coal Feeders

A raw coal feeder is a device that supplies the pulveriser with an uninterrupted flow of raw

coal from the bunker to meet system requirements. The feeders have to regulate the rate

of the coal flow corresponding to boiler load, calorific value of coal etc.

6.3.1 R o t a r y V o l u m e t r i c F e e d e r

In this type of feeder, a spider wheel is keyed to the centre of a feed roll shaft. This

shaft extends through a cylindrical core, which form the base of the feed roll. The core

is made in two halves, which are bolted to the opposite side of the feeder body, and the

spider wheel is placed in between these two halves. Numbers of plates are bolted to the

spider wheel along its periphery; these are making number of pockets. When the feeder

runs, the coal is received by the pockets formed by the plates and emptied into the

28

pulveriser at a rate, which depends on the speed of the feeder. A hinged levelling gate

held in place by spring pressure limits the amount of coal entering each pocket but allows

passage of foreign material, which might otherwise cause damage to the feeder.

6.4 Pulverisers

To effect the coal particle size reduction, needed for pulverised coal firing, machine known

as pulverisers or mill are used to grind or comminute the coal. The pulverisers are generally

based on rock and mineral-ore grinding machinery. Five major type of coal mills used

are tabulated below according to their speed

Mill Speed

Bowl mill 50-100rpm

Ball mill below 50rpm

Impact or hammer mill above 225rpm

Bearer wheel mill above 225rpm

Drum mill/ tube mill below 50rpm

6.5 Bowl Mill

Bowl mill is a vertical spindle medium speed mill. In a bowl mill the coal is pulverised

between a disc called bowl rotated by the drive assembly and rollers kept above the disc

loaded by spring loading device.

Raymond mill mostly use in Indian Thermal Power Station. Vertically this mill is divided

into four major sections;

1 Mill base or gear box

2 Mill side assembly

3. Separator body

4. Separator body top.

Coal from the raw coal feeder is fed at the centre of the bowl through a raw coal inlet chute

inserted at the centre of the separator body top. Due to centrifugal force the coal moves

towards the periphery. The three rolls exert the required grinding pressure through the

springs. The primary air supplied to the mill side moves up through the vanes around the

bowl. By the deflector liners air is deflected towards the centre of the mill which causes

29

recirculation of coal throughout the grinding area. The airs moving upwards picks fine coal

and inter the classifier through the vanes. The vanes introduces spin and as a result course

particles get separated from the stream and return through the annulus between the centre

of the feed pipe and classifier cone to the bowl for further grinding. Fine coal moves out

with air through the multiport assembly at the outlet of the classifier.

6.6 Factors Affecting Mill Performance

The performance of the mill plant especially the pulveriser output is affected by number

of factor mainly associated with the properties of coal being ground. Important of these

factors are

• Grind ability index of coal

• Fineness of milled product

• Moisture content

• Size of the row coal

• Mill wear

30

CHPTER 7

BOILER

7.1 Introduction

A boiler, also called steam generator, is designed so that heat transfer takes place between

boiler tube bundles (also called U bundles) and boiler water in the boiling area. If the U

bundles are not completely submerged, the heat transfer area, hence heat transfer rate,

hence heat sink capability decreases.

7.2 Function of Boiler Drum

The functions of the boiler drum are.

A) Separation of the saturated steam from the steam-water mixture produced by

evaporating tubes.

B) Mixing feed water from economiser and water separated from steam –water

mixture, and recirculation through the tubes.

C) Carrying out blow down for reduction of the boiler water salt concentration.

D) Treatment of the boiler water by chemical.

7.3 Steam Separator

In recirculation type of the boiler the evaporating tube supply only a steam-water mixture

to the drum. From this, the steam of high purity acceptable to the super heater and turbine

is to be separated. This separation is to be done in the limited space in the drum. Numbers

of the factors influence the separation of the water from the steam in drum; important

among them are:

The density of the water with respect to the steam.

The amount of the water in the mixture delivered to drum.

Viscosity, surface tension and other factor affected by pressure

Water level in the drum

The concentration of boiler water solids

The available pressure drop from drum internal design

In this power plant TURBO SEPARATORS are use (95 separators).

7.4 Super Heater

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Super heating of the steam is done in 14 stages. These stages having following purpose,

Heating of the steam in stage or increase of the temperature in number of the

stage.

In these stages, we also use spray for cooling the steam.

7.5 Re-Heater

Re-heater is use to re-heat the steam for the use of intermediate pressure turbine (at the

same pressure of the outlet of the HP turbine). In the re-heater steam comes from HP

turbine through CRH L&R (cold re-heat) and after re-heater steam goes to intermediate

turbine through HRH L&R (hot re- heat).

7.6 Economiser

Economisers are provided in the boilers to improve the efficiency of the boiler by

extracting the heat from the flue gases and add it as either sensible heat alone or

sensible heat and latent heat to the feed water before the water enter the evaporating surface

of the boiler.

Advantage

Provision of the economiser in the boiler brings two major advantages.

1. As the economiser recovers the heat in flue gas that leaves the boiler.

2. As the feed water is preheated in the economiser.

7.6.1 Economiser Failure

1 Over heating

2 Corrosion

3 Erosion

7.7 Furnace

Furnace is primary part of the boiler where the chemical energy available in the fuel is

converted into thermal energy by combustion. Furnace is designed for efficient and

complete combustion. Major factors that assist for efficient combustion are the temperature

inside the furnace and turbulence, which causes rapid mixing of fuel and air

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CHPTER 8

TURBINE

8.1 Introduction

Steam turbine is a rotating machine which converts heat energy of the steam to mechanical

energy.

8.2 Working Principal Of The Steam Turbine

Fig 8.1:-Multi Stage steam Turbine Generator

When the steam is allowed to expand through a narrow orifice, its assumes kinetic

energy at the expense of its enthalpy. This kinetic energy changes to mechanical energy

through the impact (impulse) or reaction of the steam against the blades.

It should be realized that the blade of the turbine obtains no motion force from the static

pressure of the steam or from any impact of the steam jet. The blades are designed

in such way, that steam will guide on or off the blade without any tendency to

strike it.

8.3 Turbine Type

Basically there are two broad classifications of the steam turbines,

1. Impules Turbine

2. Recation Turbine

8.3.1 Impulse Turbine

In the impulse turbine, the steam is expanding in the fixed nozzles. The high velocity

steam from the nozzles does work on the moving blades which cause to rotate the shaft.

The essential feature of an impulse turbine is that all pressure drops occur in nozzle

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only and there is no pressure drop in moving blade

8.3.2 Reaction Turbine

In this type, pressure is reduced in both fixed and moving blade. Both fixed and moving

blades act like nozzles and are of the same shape. Work is done by the impulse affect

due to the reversal of the direction of the high velocity steam plus a reaction affect due

to the expansion of the steam through the moving blades.

8.4 Classification of The Steam Turbine

Classification of the steam turbine is done on the basics of the following.

According to the direction of the flow

1. Axial turbine

2. Radial turbine

According to the principle of action of the steam

1. Impulse turbine

2. Reaction turbine.

According to the steam condition at inlet to turbine

1. Low pressure turbine

2. Medium pressure turbine

3. High pressure turbine

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CHAPTER 9

GENERATOR

9.1 Introduction

"An electrical generator is an electro mechanical machine which converts

mechanical energy into electrical energy"

Generator is the main part of a power plant. The generator has stator in gas cooling

construction enclosing the stator winding, core & hydrogen coolers. The cooling Medium

hydrogen is containing within the frame and circulation by fans mounted either at the ends

of the rotor .the generator is driven by directly coupled prime mover (steam turbine in

thermal plant)at constant speed of 3000rpm.

Provision has been made for circulating the cooling water in order to maintain a

constant temp of a coolant i.e. H2 as measured at the fan section side which is in touch with

the temp of the winding, core &other parts as per load.

All units have been provides with “Shandong Jinan Generating Equipment Ltd.”

make a 3-phase turbo generator. The generator mashes a closed loop of hydrogen gas

system for cooling the stator and rotor. Hydrogen gas at a pressure of 2atm is filled in a gas

tight outer closing of the generator. Hydrogen gas circulates inside the closing by two single

stage rotor mounted fans on either side of the rotor. The heated H2is in turn cooled by six

surface type water coolers axial mounted inside the generator casting. The cooled water is

supplied to H2 coolers from bcw overhead tank.

Each generator has terminal led out of its closing and a star point is formed

by sorting the neutral side’s terminal by a sorting bar. 1 phase 11000/220, 37.5KVa neutral

grounding X'mer whose secondary is laminated by laminated strip with mechanical

ventilating holes grounds the neutral.

9.2 Parts of Generator

1. Stator Body

The stator body is a totally enclosed gas tight fabricated structure suitable ribbed to rigidity.

It is designed mechanically to withstand internal pressure & forces as an event of unlikely

event of explosion of hydrogen &oil mixture withstand pressure .The function of stator

frame is to contain and support the stator core winding, hydrogen coolers and also path for

distribution of cooling hydrogen through the generator

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2. Stator Core

The rotating magnetic field flows with the core. In order to reduce the magnetizing (eddy)

current losses in the active portion of the stator core the entire core is built up of thin

lamination. The segments are stamped out from CRGO. The core contain several pockets

separated by steel spaces for radial cooling of the core

3. Stator Winding

The stator has 3-phase double layer short-pitched end bar type of winding having two

parallel paths. Each slot accommodates two bars. The lower & upper bar are displaced from

each other by one winding pitch and connected at their ends so as to form coil groups. Each

bar consists of solid as well as hollow conductors with cooling water passing through the

later alternator. Arrangement of hallows and solid conductor ensures an optimum solution

for increasing current and losses. The high voltage insulation is provided by thermo setting

insulator using mica paper type (Resin Rich)

4. Distillate Header

Ring type, water header made up of copper is provided separate for distillate inlet & outlet

in the stator of turbine side .The headers are support on insulator and insulated from stator

body. At turbine side each individual bas is connected with inlet/outlet header. The vent

pipe connection is at the top of the both inlet & outlet header .The vent pipes are connected

at gas trap desire to measure the extent of hydrogen leakage into water circuit.

5. Terminal Bushing

Three phases and six neutral terminals are brought out from the stator through bushing

which are capable of withstanding high voltage and provided with gas tight joints the

bushing is assembled and tested for flow, leakage to ensure tightness and continuous flow

of water.

6. End Shield

To make the stator body gas tight the end shield are fitted gas tightness is achieved by

putting a rubber sealing cord .The end shields are made in two halves convenience during

erection and installation.

36

7. Rotor

The rotor shaft is a single piece forging the longitudinal slot for inserting the field winding.

The slots are distributed over the circumference so that two field solid poles are obtained.

After completion of rotor assembly the rotor is balanced at different speed test at 120% of

rated speed for 2minuts the rotor conductor is of silver bearing copper. The field copper

current is supplied to the rotor winding through two semiconductor copper bars arranged

in hollow bars of rotor through radial current carrying bolts.

8. Bearing

The generator bearings are of pedestal type with spherical seating. It allows self-alignment

and supported on a separate pedestal on slip ring side. The bearing has a provision of

hydraulic shaft lifting during start up and turning gear operation to eliminate shaft current

shaft bearing and its pipes are insulated from earth.

9. Brush Gear

The current carrying gear assembly is rigidly fixed on the extent peat of the bearing pedestal

on the exciter side. There are two brushes gear stand for +tive and -tive supply. The field

to stator winding provides the brush gear. The brushes are loaded to maintain required

contact pressure of 0.2kg/cm2 and the brushes during normal operation condition have low

coefficient of friction and are self-lubricating.

Fig 9.1:-Cross Section View Generator

9.3 Starting of generator

To start the generator the following procedure is followed:

37

Generator field breakers should be opened.

Generator circuit breaker should be opened.

The shaft seal oil is system should be kept under the operation.

Hydrogen filling must be completed.

As generator is brought up to the speed .The following must be checked.

Oil pump delivery pressure and quantity of oil.

Oil leakage from bearing.

Mechanical balance by taking shaft variation.

1. The steady state temp of bearing and lubricating oil at rated speed must be checked.

2. The generator field breaker is closed and drying out of turbo generator is carried out.

3. Auto voltage regulator may be adjusted and the voltage adjusting unit on regulator may

set to get the desired voltage.

4. Inducing 130% of rated voltage& maintaining it for five minutes can test insulation of

stator winding.

5. Now generator is ready to be synchronized with system.

To synchronize the Generator with system below conditions must be satisfied:

Phase sequence must be same

Frequency must be same

Voltage generated must be same

9.4 Shutting down of generator

To shut down a generator we follow below procedure

Cut off load gradually from the machine and open generator C.B.

The switch for de excitation provides A.V.R is switched on.

The water to the hydrogen coolers and steam to turbine is to be cut off.

The speed of Generator is reduced to20-25 % of rated.

9.5 Excitation system

The electrical power requires D.C excited magnets for its field system. The excitation

system must be stable in operation and must respond quickly to excitation current

38

requirement. When excitation control is by a fast regulating or a supply is given from

transformer and then rectified.

The main function of excited system is to supply the required excitation current at the rated

load or any operating load condition. It should be able to adjust the field current of the

generator either by normal control or but automatic control so that for all operation between

known load and rated the terminal voltage of the synchronous machine is maintained at its

value.

9.6 Types of Excitation

There have been many developed in excitation system design and research is continuing.

The ultimate aim is to achieve one system idle in rate of response, simplicity, reliability

and accuracy. Excitation systems are:

Conventional DC system

Brushless excitation system

Static excitation system

9.7 Turbo Generator Specification

Specification

KVA 247000

PF 0.85

Volts of stator 15750

Amperes of stator 9050

Volts of rotor 310

Amperes of rotor 2600

RPM 3000

Frequency 50 Hz

Phase 3

Connection YY

Coolant water (stator) & hydrogen (rotor)

Gas pressure 3.5kg/cm-sq.

39

Insulation class B

40

CHAPTER 10

SWITCHYARD

10.1 Introduction

Switchyard is considered as the HEART of the Power Plant. Power generated can be worthy

only if it is successfully transmitted and received by its consumers. Switchyard plays a very

important role as a junction between the generation and transmission. It is a junction, which

carries the generated power to its destination (i.e. consumers) In BSTPP there are two

switchyards:-

(i) 400KV SWITCHYARD

(ii) 132KV SWITCHYARD

10.1.1 400 KV SWITCHYARD

There are total 22 bay in 400 KV switchyard. A Bay is basically a way for the incoming

power from generator as well as outgoing power for distribution.

5 Bay for each generating transformer

3 Bay for ICT(Inter Connecting Transformer)

2 Bay for PATNA line

2 Bay for KAHALGAON line

2 Bay for BALIA line

7 for FUTURE line

1 Bay for SHUNT REACTOR

There are four main buses in 400 KV switchyard.

Ø Main bus – 1& 2

Ø Main bus – 3&4

10.1.2 132 KV SWITCHYARD

There are total 11 Bay in 132 KV switchyard.

3 Bay for ICT (Inter Connecting Transformer)

5 Bay for S.T (Station Transformer)

2 Bay for MST (Miscellaneous Service Transformer)

1 Bay for Bus Coupler

41

There are two main buses in 132 KV switchyard.

Main bus - 1

Main bus - 2

10.2 Components of Switchyard

Fig 10.1:-Component of Switchyard

1. Insulator

The insulators mainly serve two purposes. First of all they support the conductor and

confined the high current of the line to the conductor. The most common material for the

manufacturing of insulators is Porcelain. Below mentioned are the types of Insulators used

in switchyard,

Pin Insulator

Post Type

Suspension Insulator

Strain Insulator

2. Bus bar

In electrical power distribution, a bus bar is a strip or bar of copper, brass or aluminum that

conducts electricity within a switchboard, distribution board, substation, battery bank, or

other electrical apparatus.

3. Lightning arrester

42

A lightning arrester is a device used on electrical power systems and telecommunications

systems to protect the insulation and conductors of the system from the damaging effects

of lightning. The typical lightning arrester has a high-voltage terminal and a ground

terminal.

4. Wave trap

Wave Traps are used at sub-stations using Power Line Carrier Communication (PLCC).

PLCC is used to transmit communication and control information at a high frequency over

the power lines. This reduces need for a separate infra for communication between sub-

stations

5. Circuit Breaker

A circuit breaker is an automatically operated electrical switch designed to protect an

electrical circuit from damage caused by overload or short circuit. Its basic function is to

detect a fault condition and interrupt current flow.

6. Capacitive Voltage Transformer

A capacitor voltage transformer (CVT), or capacitance-coupled voltage transformer

(CCVT), is a transformer used in power systems to step down extra high voltage signals

and provide a low voltage signal, for metering or operating a protective relay

7. Current Transformer

Fig 10.2:-Connection of Current Transformer

The current transformer is a step up transformer , it means current is stepped down to a

very low value (generally 1 A or 5 A) so that it can be used for measuring and protection

43

purposes .C.T is designed in such a way its Core Material could give high accuracy with

low saturation factor. Core Material is generally made of CRGO Silicon steel for very low

loss characteristics, µ material (Alloy of Ni-Fe) is used. Current Transformer is used for

basically two major functions: -

1 .Metering:-which means current measurement.

2. Protection:-such as over current protection, overload earth fault protection, Bus-bar

protection, Bus differential protection. CT is typically described by its current ratio from

primary to secondary. There is not more difference between 132 KV and 400 KV C.T, only

current ratio differ

10.1. Specification of 132KV C.T

Standard IS2705

Highest System Voltage 145 KV

Insulation Level 275/650 KV

Frequency 50 HZ

Short Time Current 31.5 KA for 1 sec

Rated Primary Current 1200A

Extended Current 120

10.2. Specification of 400 KV C.T

Standard IS2705

Rated Voltage 420 KV

Insulation Level 275/650 KV

Frequency 50 Hz

Short Time Current 31.5 KA for 1 sec

Rated Continuous normal Current 2000 A

Extended Current 200/120%

Oil weight 750 kg

Total weight 2500 K

44

8. Isolator

An isolator is one, which can break an electrical circuit when the circuit is to be switched

on no load. These are normally used in various circuits for the purposes of isolating a certain

portion when required for maintenance etc. It is always used in OFF-LOAD condition.

“Switching isolators" are capable of interrupting transformer magnetized currents;

interrupting line charging current; and Load transfer switching

9. Surge Arrester

This will protect the equipment from transient, surge and high voltages. They are generally

connected in parallel to the equipment to be protected and function to divert the surge

current safely to ground.

10. Earth switches on Isolator

Earth Switch is used to discharge the residual charge on the circuit to the earth safely. Earth

switch is mounted on the frame of the isolators. After the equipment is isolated then the

earth rod is connected so that the residual charges present on the device will be grounded.

This is mainly done for safeguarding human life from getting a shock.

11. Protective relay

Fig 10.3 cross section of relay

A protective relay is a device that detects the fault and initiates the Operation of the Circuit

breaker to isolate the faulty element from the rest of the system. The relay sense fault and

gives the command to the circuit breaker and the circuit breaker is operated. The relay

receives the command from the instruments transformers (i.e. CTs & PTs).

45

CHAPTER 11

TRANSFORMER

11.1 Introduction

It is a static machine which increases or decreases the AC voltage without changing the

frequency of the supply. It is a device that:

Transfers electric power from one circuit to another.

It accomplishes this by electromagnetic induction.

In this the two electric circuits are in mutual inductive influence of each other.

Transformer is made up of following parts:-

1. Core

2. Winding

3. On load tap changer

4. Conservator tank

5. Brushing

6. Auxiliary equipment’s

7. Cooling system

Fig:-11.1 Cross Section View Transformer

46

1. Core

It is an essential feature of power transformer. Magnetic circuit is three-limb core type

construction. Each limb has interleaved points with top & bottom yoke. The three limbs

have winding. The lamination are made up of high grade none aging, cold rolled grain

oriented silicon steel. This yolk are clamped by mean of bolts and nuts .The tapping leads

are connected on tap changer which is mounted outside the transformer.

2. Winding

The inner most coil near the core term low voltage winding. This is spiral Coil. Axial coil

ducts are provided inside and the coil. Outside it is the high voltage winding. These are also

disc type winding provided with axial and radial ducts. Line load is taken out from top of

coil. Static rings have been provided and the line ends of H.V coil for better impulse

distribution across the coil.

3. On Load Tap Changer

An on load tap changer is a device used for changing the taping connection of winding

Suitable for operation while the X'mer is energized on load. The tap changer is a operated

by a motor operated driving m/c by load or remote control and a handle is fined for manual

operation in any emergency tank bodies for transformer are made from rolled steel plates

which is fabricated to from the container.

4. Conservator Tank

Conservator tank is of steel plate .it is designed to withstand a vacuum pressure of 755mm.

They also made of rolled steel, which is fabricated to form one container. Internal fitting

and clamps is poisoned and welded internally small transformer, which have cooling tubes.

Such transformers, have plane tank with provision for pipe and valves to direct and control

the oil flow.

5. Brushing

When transformer has been connected to high voltage line care must be taken to prevent

flashover one H.V connection to earthed tank. This is done by means of bushing. The

simplest bushing is a molded high quality glazed porcelain insulated with the conductor

through its center these bushing can be used up to 33KV

47

6. Cooling System

The losses in any transformer can be of the order of several hundred KW and the efficiency

will be about 90.5% on full load to prevent deterioration of insulation due to temperature.

This waste heat must be dissipated by carefully designing the cooling system. The losses

comprise of copper losses, hysterics losses and eddy current losses. In large transformer the

usual method of exciting the heat from the core subsequently cooled by another means of

radiator over which circulation by natural convection air is blown. The later be known as

air blast cooling to assist in cooling most large unit have forced oil circulation .The oil have

been pumped through transformer & cooling tubes.

11.2 Classification

(I) According To Core

a) Core type transformer

b) Shell type transformer

c) Berry type transformer

(II) According To phases

a) 1-phase transformer

b) 3-phase transformer

(III) According to the purpose for which used

a) Distribution transformer

b) Transmission transformer

c) Generator transformer

d) Station transformer

e) Unit Auxiliary transformer (UAT)

11.3 Generating Transformer

48

Fig 11.2:-Generator transformer

A generating transformer is a single – phase power transformer (3 single phase units shall

form a bank). Generating Transformer steps–up the generated voltage of 24 KV by

alternator to a higher voltage of 400 KV (hence, working as a step-up Transformer).This

voltage of 400 KV is then transmitted to switchyard

Specification

HV Nominal Voltage 420/sqrt (3) KV

LV Nominal Voltage 24 KV

Rated Power 260 MVA

HV Nominal Current 1072.22 A

LV Nominal Current 10833.33 A

Frequency 50 Hz

Lightning impulse withstand voltage 1425 kVp(HV)170 kVp(LV)95 kVp(HV)

Tap range ± 5% in steps of 2.5%on HV neutral side

Oil weight 60430 Kg

Total weight 250930K

11.4 Inter Connecting Transformer

An ICT is a 3-phase auto transformer used to interconnect 400 KV switchyard and 132 KV

switchyard

49

Specification

Standard IS: 2026

Type Auto Transformer

Rated power 200 MVA (HV) 200 MVA (MV) 67 MVA (LV)

Current rating of different cooling 40% /60%/100% (A)

Core and winding mass 115600 Kgs

Oil mass 81880 Kgs

Total oil quantity 92000 liter

11.5 Station transformer

Station Transformer is used only for initializing the start-up of the station (Main Plant).It

is very beneficial during emergency situations such as tripping of Units, shut-down

etc.Station transformers is used to start

Station auxiliaries are required for generating services such as coal and ash handling

system, lighting system, water purifying system etc. It gets the supply in its primary from

132 KV switchyard, steps down it to 11.5KV which is used for starting various equipment’s

& devices used in the Main power plant

Specification

Standard IS: 2026/77-81

Type Three Winding

Rated output 90/45/45 MVA

Cooling ONAN/ONAF

Rated voltage 132 KV (HV) 11.5 KV (LV1 & LV2)

Core & coil mass 60500 Kg

Oil quantity 33700 Liter

Total mass 121500 K

11.6 Unit Transformer

50

Unit transformer is directly coupled to the unit itself so when that unit is in running

condition it supplies power to which are coupled to auxiliaries directly or through unit

auxiliary transformer depending upon load. Unit auxiliaries are those which are directly

associated with the generating unit such as ID and FD fans, Boiler feed pumps, coal mills,

fans, circulating water pumps etc.

Specification

Rated output 35 MVA

Cooling ONAN/ONAF

Voltage ratio 24 / 11.5 KV

Frequency 50 Hz

Phases 3

ONAN rating in 80% of rated MVA

11.7 Miscellaneous Service transformer

Miscellaneous service transformer are used to supply miscellaneous loads of plant. It is a

two winding transformer connected to 132 KV switchyard.

Specification

Standard IS: 2026 /77-81

Rated output 16 MVA

Full load rated current 69.98 A803.27 A

Cooling ONAN

Type Two winding

Voltage ratio 132 / 11.5 KV

Frequency 50 Hz

Phase Three

Core & coil mass 17650 Kg

Oil quantity 10400 liter

Total mass 37600 kg

51

CONCLUSION

On the completing of my vocational training at Thermal Power Station

BARH, I have come to know about how the very necessity of our life

nowadays i.e. Electricity is Generated. What all the processes are needed to

generate and run the power plant on 24X7 basis.

Water and air are the most precious in the world so we have to save these

things by recycling water or decreasing pollution.

Training gave me an opportunity to clean my concepts from practical point of

view with the availability of the machinery of such larger rate.

Finally as my industrial training came to an end, I felt that this

additional knowledge and exposure would certainly help me mould career

in the technical field and would also give us that extra bit of advantage and

recognition required to enhance my profile.

52

REFERENCES

http://www.ntpc.co.in

https://en.wikipedia.org/wiki/Barh_Super_Thermal_Power_Station

http://www.electrical4u.com