CHAPTER: 1

INTRODUCTION

Kanti bijlee utpadan nigam limited (Muzaffarpur thermal power station) is a joint venture of

National thermal power corporation (N.T.P.C) and Bihar State Electricity Board (B.S.E.B). It is

situated in Muzaffarpur district of bihar across National highway.

It has a installed capacity of 220 MW (2 X 110 MW).Another two units of 2 X 195 MW is

proposed and the work is already started. The coal required for power generation comes from

raniganj and mugma.The source of water is old bagmati river and canal. The ash as a result of

combustion of coal is deposited at ash dike across the river.

1.1) INTRODUCTION TO THERMAL POWER PLANT

FIG-1 THERMAL POWER PLANT

A thermal power plant is a power plant in which the prime mover is steam driven. Water is

heated, turns in to steam and spins a steam turbine which drives an electrical generator. After it

passes through the turbine, the steam is condensed in a condenser; this is known as Rankine

cycle .such power stations are most usually constructed on a very large scale and designed for

continuous operation.

1

Reciprocating steam engines have been used for mechanical power sources since the 18 century,

with notable improvements being made by James watt. The very first commercial central

electrical generating stations in New York and London in 1882 also used reciprocating steam

engines. By the 1920s any central station larger than a few thousands kilowatt would use a

turbine prime mover.

1.2) EFFICIENCY

The efficiency of a conventional thermal power station considered as energy produced at the

plant bus bars compared with the heating value of the fuel consumed ,is typically 33% to 48%

efficient.

1.3) COMPONENTS OF A TYPICAL THERMAL POWER PLANT

1. Cooling tower

2. Cooling water pump

3. Three phase transmission line

4. Step up transformer

5. Electrical generator

6. Boiler feedwater pump

7. Low pressure steam turbine

8. Surface condenser

9. Intermediate pressure steam turbine

10. Steam control valve

11. High pressure steam turbine

12. Feed water heater

13 .Coal conveyor

14.Coal pulverizer

15.Boiler steam drum

16. Bottom ash hopper

17. Superheater

18. Forced draught fan.

19. Reheater

20. Economiser

21. Air preheater

22. Precipitator

23. Induced Draught fan

24. Ash dike

2

CHAPTER: 2

FUEL & FUEL HANDLING SPECIFICATIONS

The fuel (coal) used at MTPS comes from two sourses, that are Raniganj and Mugma.The grade

of coal is BCD.

Type of fuel = Pulverized coal, heavy oil & L.D.O.

Number of mills = 06

Type of mills = Pressurized type bowl mill.

Number of PA fan = 02 Number of F.D fan= 02

Number of I.D fan = 03 (1 standby)

2.1) Fuel preparation system:

In coal-fired power stations, the raw feed coal is brought through railway wagons to the coal

storage area. Wagon triplers are used to empty the rail wagons and coal from here are directly

sent to coal conveyer units from where coal is to be forwarded to crusher house for pulverization

and from there further forwarded to coal bunkers beside the boiler through conveyer belts.

Manual coal feeding is carried out through crane.

3

FIG-2 WAGON TRIPLER

Conveyer belt arrangement is accompanied by pull cord switch which operates at 16A & 440 V

A.C. It urgently stops the conveyer belt system in case of fault. A number of pull cord switch is

connected in series.

A suspended magnet (16 KVA Electromagnetic separators) is lifted above conveyer belts to

attract metal pieces from the coal passing above the conveyer belts.

FIG-3 CONVEYOR BELTS

2.2) CRUSHER HOUSE:

From the hopper coal reaches to surge hopper through conveyer belts and from there it get

divided in two parts called as vibrating screen 1 and vibrating screen 2. From there fine particles

bypass to number three belt and large pieces of coal goes to the crusher. Shaft of the crusher is

connected to foot coupling drive (FCUI) drive which contains oil at 45 degree empty. More

speed of FCUI drive more speed of crusher so, more crushing of coal. From here pulverized coal

fall on conveyer belt arrangement as shown in figure.

4

FIG-4 PULVERIZER

Inside the crusher house there is an induction motor to move the conveyer belts over the rollers.

The specifications of the induction motor are as follows:

Power = 100 KW

Volts = 415

Rpm = 1480

Amperes = 169

Phase = 3

Frequency = 50 Hz

Horse power = 133

5

CHAPTER:3

GENERATION OF STEAM

3.1) BOILER:

Type of boiler- single drum, tangential firing & reheat type.

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid

exits the boiler for use in various processes or heating applications.

The pressure vessel in a boiler is usually made of steel, stainless steel or wrought iron. Copper

was often used for fireboxes (particularly for steam locomotives), because of its better thermal

conductivity; however, in recent times, the high price of copper often makes this an uneconomic

choice and cheaper substitutes (such as steel) are used instead.

3.2) BOILER FITTINGS AND ACCESSORIES:

Safety valve: It is used to relieve pressure and prevent possible explosion of a boiler.

Water level indicators: They show the operator the level of fluid in boiler, also known as a

sight

glass, water gauge or water column is provided.

Bottom blow down valves: They provide a means for removing solid particulates that condense

and lay on the bottom of a boiler. As the name implies, this valve is usually located directly on

the bottom of the boiler, and is occasionally opened to use the pressure in the boiler to push

these particulates out.

Continuous blow down valves: This allows a small quantity of water to escape continuously.

Its purpose is to prevent the water in the boiler becoming saturated with dissolved salts.

Saturation will lead to foaming and cause water droplets to be carried over with steam, a

condition known as priming.

6

Low water cutoff: It is a mechanical means (usually a float switch) that is used to turn off the

burner or shut off fuel to the boiler to prevent it from running once the water goes below a

certain point ,thus preventing boiler from rupture on account of dry firing.

Surface blow down line: It provides a means for removing foam or other light weight non-

condensable substances that tend to flow on top of the water inside the boiler.

Circulating pump: It is designed to circulate water back to the boiler after it has expelled some

of its heat.

Feed water check valve or clack valve: A no return stop valve in the feed water line. This may

be fitted to the side of the boiler, just below the water level or to the top of the boiler. A top

mounted check valve is called a top feed and is intended to reduce the nuisance of Hme scale. It

doesn't prevent lime scale formation but causes it to be precipitated in a powdery form which is

easily washed out of the boiler.

Chemical injection line: A connection to add chemicals for controlling feed water pH.

3.3) STEAM GENERATION:

After the coal reaches bunkers which are at a height of 53m above the ground ,coal reaches

bunkers through conveyer belts. The bottom of the bunker is coupled to motor which extracts

coal from bunker.

At a height of 15m from the ground there is coal mill or pulverizer. Below the pulverizer there is

a bowl like structure which is movable and a roller is placed at the top of the bowl like structure

which crushes the coal and pulverized coal comes out of the bowl by virtue of centrifugal force.

Now this pulverized coal is brought to the boiler through primary air fan.

There are four mills and corresponding to each mill there is six elevations (A,B,C,D,E,F) and for

each mill the pulverized coal is brought by primary air fan is fed to boiler through six elevations

as given corresponding to each mill.

Inside the boiler pulverized coal is now fed and there are water walls in the boiler which gets

heated on account of combustion of coal & hence steam is generated.

7

The generated steam reaches the boiler drum which is above the boiler and it is maintained at

constant pressure such that high temperature steam comes out of the drum. The steam generated

which is not suitably heated is again sent to boiler for further heating where there is ring header

(a small area of heating), inside boiler & steam after getting heated reaches boiler drum due to

density difference & comes out of it.

Air path: External fans are provided to give sufficient air for combustion. The forced draught

fan takes air from the atmosphere and, first warming it in the air preheater for better combustion,

injects it via the air nozzles on the furnace wall.

The induced draught fan assists the FD fan by drawing out combustible gases from the furnace,

maintaining a slightly negative pressure in to avoid backfiring through any opening. At the

furnace outlet and before the furnace gases are handled by the ID fan, fine dust carried by outlet

gases is removed to avoid atmospheric pollution. This is an environmental limitation prescribed

by law, and additionally minimizes erosion of the ID fan.

8

CHAPTER:4

COOLING TOWERS

Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere.

Cooling towers may either use the evaporation of water to remove process heat and cool the

working fluid or rely solely on air to cool the working fluid.

FIG-5 COOLING TOWER

Common applications include cooling the circulating water used in power plants and achieve

cooling. The towers vary in size from small roof top units to very large hyperboloid structure

that can be up to 200 meters tall and 100 meters in diameter, or rectangular structures that can be

over 40 meters tall and 80 meters long. Smaller towers are normally factory built, while larger

ones are constructed on site.

4.1) D.M. PLANT:

9

The water is treated in this portion such that it is free of all the mineral impurities. Hence the

name demineralization plant. Thus the water becomes fit for further use in the boiler drum with

high value of steam formation and least damage to the turbine. This leads to the increases life of

the boiler and an improvement in efficiency.

4.2) BOILER FEED PUMP:

It is a specific type of pump used to pump feed water in to a steam boiler. The water may be

freshly supplied or returning condensate produced as a result of the condensation of the steam

produced by the boiler. These pumps are normally high pressure units that use suction from a

condensate return system and can be of the centrifugal pump type or positive displacement type.

4.3) CONDENSER:

The surface condenser is a shell and tube heat exchanger in which cooling water is circulated

through the tubes. The exhaust steam from the low pressure turbine enter the shell where it is

cooled and converted to water by flowing over the tubes as shown in the adjacent diagram. Such

condensers use steam ejectors or rotary motor-driven exhausters for continuous removal of air

and gases from the steam side to maintain vacuum.

FIG-6 CONDENSER

10

For best efficiency, the temperature in the condenser must be kept as low as practical in order to

achieve lowest possible pressure in the condensing steam. The condenser generally uses either

circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once

through water from a river, lake or ocean.

CHAPTER:5

ASH HANDLING

Coal burnt in the boiler produces a large amount of ash, out of these only 20% of ash settles at

the bottom of the boiler and through ash slurry pumps these are sent to ash dike across river

bagmati. Still 80% of the ash is now with the flue gases. The pressure maintained within the

boiler is negative on account of the reason that-

(a.) Flue gases can be ejected from the boiler easily.

(b.) A cylindrical flame is required in boiler.

(c.) To ensure that there is no backfiring through any of the nozzles.

After the flue gases are ejected from the boiler flue gases passes through superheater, reheater &

economizer. The flue gases coming out of economizer has a temperature of 275-325 degree

Celsius before it enters air preheater. After coming out of the air preheater flue gases get divided

in to two paths-

(a.) First accompanied by induced draught fan.

(b.) Path leading to electrostatic precipitator (E.S.P).

Electrostatic precipitator: Electrostatic precipitator consists of pair of seven plates in which of

a pair first plate is negatively charged and second is positively charged & as a result field is

created. The ash get deposited on the positive plate of the pair of seven plates on all the seven

pair of plates and by continuous hammering , it is removed from the plates and from here it is

deposited at ash dike across river by the use of slurry pumps.

The flue gases consist of carbon dioxide, nitrogen di oxide and sulphur dioxide. Induced draught

fan extract these gases and forward it to chimney from where it is exhausted. The flue gases

coming out of the chimney has a temperature of at least 120 degree Celsius.11

CHAPTER:6

TURBINE: SPECIFICATIONS & OPERATION

Type of turbine: Reheat type

Number of cycles: 3(HP, IP, LP)

Temperature of hp turbine inlet: 535 degree Celsius

Pressure at hp turbine inlet: 130 atm

Temperature at IP turbine inlet: 535 degree Celsius

Turbine speed: 3000 rpm

Condenser vacuum pressure: 0.1 kg/cm^2

12

FIG-7 TURBINE

6.1) INTRODUCTION:

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and

converts it in to useful mechanical work.

It has almost completely replaced the reciprocating piston steam engine (invented by Thomas

Newcomen and greatly improved by James watt) primarily because of its greater thermal

efficiency and high power to weight ratio. Because the turbine generates rotary motion, it is

particularly suited to be used to drive an electrical generator -about 80% of all electric

generation in the world is by the use of steam turbines. The steam turbine is a form of heat

engine that derives much of its improvement in thermodynamic efficiency through the use of

multiple stages in the expansion of the steam, which results in a closer approach to the ideal

reversible process.

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6.2) OPERATION OF TURBINE IN UNIT:

There are three stages of operation:

(a.) High pressure (H.P)

(b.) Intermediate pressure (LP)

(c.) Low pressure (L.P)

The three stages of expansion of the steam is used because of the large shaft length. In the first

stage the high pressure steam from the output of the boiler is given to the first turbine unit .The

steam expands on the blades in this stage and sent to the next stage and so on.

NOTE: A special operation motor is mounted on the shaft of the turbine in order to keep it

rotating even in non-generating condition. This is done in order to keep the coupled shaft of the

turbine and the alternator from bending.

From superheater steam divided in two parts, left and right then after they pass through oil

operated control valve. When the pressure of the oil increase up to suitable level plunger above

rises and steam enters the HP turbine. To increase oil pressure we have arrangement in control

room and manual arrangement near HP turbine which when rotated in anti clockwise direction

increases the pressure of oil and plunger rises.

Control valves start opening at 0.7 and get fully opened at 1.5 units of pressure.

After passing through HP turbine steam again enters boiler and after getting heated it enters the

LP

turbine through valves present on left and right positions of the turbine.

Another valve present on LP turbine that is low pressure control valve (L.P.C.L) that is on the

adjacent positions.

L.P.C.L valves starts opening at a pressure of 0.5 units and get fully opened at pressure of 1 unit

of pressure. Steam then enters low pressure turbine, having definite arrangement, when steam

enters inside it gas expands and this in turn rotates the blades of the turbine. The L.P turbine is

coupled to generator which produces electricity.

14

Three phase supply is obtained from the stator of the generator through hexagonal pipes which is

connected to generating transformer.

FIG-8 GENERATING TRANSFORMER

CHAPTER:7

GENERATION UNIT/ALTERNATOR

The generation unit consists of the following sub-parts:

(a.) Turbine assembly

(b.) Alternator

(c.) Excitation Transformer.

15

FIG-9 GENERATOR

7.1) GENERATOR RATING/SPECIFICATIONS:

MW Rating = 110MW

MVA Rating = 137.5 MVA

KV Rating =11KV (+/- 5 %)

Frequency = 50 Hz

Power Factor = 0.8 lagging

7.2) ALTERNATOR:

An alternator is an electromechanical device that converts mechanical energy to electrical energy

in the form of alternating current.

Most alternators use a rotating magnetic field but linear alternators are occasionally used. In

principle, any AC electrical generator can be called an alternator, but usually the word refers to

small rotating machines driven by automotive and other internal combustion engines. Alternators

in power stations driven by steam turbines are called turbo-alternators.

16

Basic principle:

Alternators generate electricity using the same principle as DC generators, namely, when the

magnetic field around a conductor changes, a current is induced in the conductor. Typically, a

rotating magnet, called the rotor turns within a stationary set of conductors wound in coils on an

iron core, called the stator. The field cuts across the conductors, generating an induced emf

(electromotive force), as the mechanical input causes the rotor to turn.

The rotating magnetic field induces an AC voltage in the stator windings. Often there are three

sets of stator windings, physically offset so that the rotating magnetic field produces a three

phase current, displaced by one-third of a period with respect to each other.

The rotors magnetic field may be produced by induction (as in a "brush-less" alternator), by

permanent magnets (as in very small machines), or by a rotor winding energized with direct

current through slip rings and brushes. The rotors magnetic field may even be provided by

stationary field winding, with moving poles in the rotor. Automotive alternators invariably use a

rotor winding, which allows control of the alternators generated voltage by varying the current in

the rotor field winding. Permanent magnet machines avoid the loss due to magnetizing current in

the rotor, but are restricted in size, owing to the cost of the magnet material. Since the permanent

magnet field is constant, the terminal voltage varies directly with the speed of the generator.

Brushless AC generators are usually larger machines than those used in automotive applications.

An automatic voltage control device controls the field current to keep output voltage constant. If

the output voltage from the stationary armature coils drops due to an increase in demand, more

current is fed into the rotating field coils through the Automatic Voltage Regulator or AVR.

17

CHAPTER:8

TRANSFORMERS

A transformer is a static device that transfers power from one circuit to another through

inductively coupled electrical conductors without change in frequency.

18

FIG-10 TRANSFORMER

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductors—the transformer's coils. A varying current in the first or primary

winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic

field through the secondary winding this varying magnetic field induces a varying electromotive

force (EMF), or "voltage", in the secondary winding. This effect is called mutual induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding

and electrical energy will be transferred from the primary circuit through the transformer to the

load. In an ideal transformer, the induced voltage in the secondary winding (V s ) is in proportion

to the primary voltage (V p ) , and is given by the ratio of the number of turns in the secondary (N s )

to the number of turns in the primary (N p ) as follows:

By appropriate selection of the ratio of turns, a transformer thus allows an alternating current

(AC) voltage to be "stepped up" by making N s greater than N p , or "stepped down" by making N s

less than N p .

In the vast majority of transformers, the windings are coils wound around a ferromagnetic core,

air-core transformers being a notable exception.19

Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage

microphone to huge units weighing hundreds of tons used to interconnect portions of power

grids. All operate with the same basic principles, although the range of designs is wide. While

new technologies have eliminated the need for transformers in some electronic circuits,

transformers are still found in nearly all electronic devices designed for household ("mains")

voltage. Transformers are essential for high-voltage electric power transmission, which makes

long-distance transmission economically practical.

8.1) Basic principle:

The transformer is based on two principles: first, that an electric current can produce a magnetic

field (electromagnetism), and, second that a changing magnetic field within a coil of wire

induces a voltage across the ends of the coil (electromagnetic induction).

FIG-11 WINDING OF TRANSFORMER

Changing the current in the primary coil changes the magnetic flux that is developed. The

changing magnetic flux induces a voltage in the secondary coil.

An ideal transformer is shown in the adjacent figure. Current passing through the primary coil

creates a magnetic field. The primary and secondary coils are wrapped around a core of very

20

high magnetic permeability, such as iron, so that most of the magnetic flux passes through both

the primary and secondary coils.

Induction law

The voltage induced across the secondary coil may be calculated from Faraday's law of

induction, which states that:The rate of change of flux linkage in a coil is equal to the induced

emf.

If the turns of the coil are oriented perpendicular to the magnetic field lines, the flux is the

product of the magnetic flux density and the area ,4 through which it cuts. The area is constant,

being equal to the cross-sectional area of the transformer core, whereas the magnetic field varies

with time according to the excitation of the primary. Since the same magnetic flux passes

through both the primary and secondary coils in an ideal transformer, the instantaneous voltage

across the primary winding equals

Taking the ratio of the two equations for V s and V p gives the basic equation for stepping up or

stepping down the voltage

Np/Ns is known as the Turns ratio, and is the primary functional characteristic of any

transformer. In the case of step-up transformers, this may sometimes be stated as the reciprocal,

NJNp. Turns ratio is commonly expressed as an irreducible fraction or ratio: for example, a

transformer with primary and secondary windings of, respectively, 100 and 150 turns is said to

have a turns ratio of 2:3 rather than 0.667 or 100:150.

8.2) TRANSFORMER RATINGS:

(a.) Generating transformer (G.T):-

Manufactured by BHEL Bhopal Three phase21

Oil Temperature rise: 50 degree c

Winding Temperature rise: 55 to 60 degree c

Type of cooling: oil cooled

MVA Rating: 140 MVA

KV Rating: 230/11 KV

Frequency: 50 HZ

(b.) Station Transformer (S.T):-

Manufactured by BHEL Bhopal.

Three phase

Oil Temperature rise: 50 degree c

Winding Temperature rise: 55 degree c

Type of cooling: Oil cooled

MVA Rating: 31.5 MVA

KV rating: 220/6.6KV

Frequency: 50 HZ

(c.) Unit Auxiliary Transformer:-

Manufactured by BHEL Bhopal

Three phase

Oil Temperature rise: 50 degree c

Winding Temperature rise: 55 to 60 degree c

Type of cooling: Oil cooled

MVA Rating: 20 MVA

KV Rating: 11/7 KV

Total number of transformers = 13

Station service transformer = 02

22

Sub-Station service transformer =02

Cooling tower transformer = 02

Coal handling transformer = 02

Ash handling transformer = 02

Electrostatic pressurizer = 03

Use of various transformers in the plant depending on their ratings is as following:-Generating

transformer is used for the purpose of stepping up the voltage to 220 KV bus bar in order for

high voltage transmission, to reduce the line losses.

Station transformer has the ratings as specified above and used as the unit which receives the

power from the incoming bus and gives it to the plant switchgear in order to provide power for

the initial start up and operation of each unit in order for it to start generating and transmitting

power. Another use of station transformer is to supply power to the various auxiliary equipment

when the plant has none of its unit in generating mode.

Unit auxiliary transformer is used only when the unit is generating. As explained earlier the

station transformer supplies power for the initial start up, but as the plant starts to generate

power this auxiliary transformer is a 11/7 KV transformer.

Tappings are taken out of the generator feeding ducts which are given to the UAT and it supplies

power for the operation of the auxiliary equipments. At this point of time the station transformer

stops to operate and the plant becomes self sustaining.

CHAPTER:9

POWER GRID

23

After the generation is done the 110 MW of power needs to be transmitted and distributed to the

various load centres. Since electrical power cannot be stored at one place it needs to be supplied

to the required areas as developed.

The station transformer is used to step up the 11KV generated voltage in to 220 KV transmitting

voltage. This is done because it has its own benefits of reduction in losses and improvement in

the transmission efficiency. There is a requirement of various protection gears in order for safe

and continuous operation. This is where the isolators and circuit breakers come in to play.

The grid present in the KBUNL has a switchyard which can receive and transmit power at two

values of voltages that are 220 KV and 132 KV. This can be better understood by the single line

diagram as shown for the 220 KV switchyard. Now we need to discuss the various parts of the

switchyard in detail.

9.1) THE 220 KV SWITCHYARD:

The switch yard consists of three buses:

(a.) Main bus 1

(b.) Main bus 2

(c.) Bypass bus

The three buses are installed in a manner such that the main bus 1 and 2 are used for either

receiving or sending power from station transformer 1 and 2 respectively. The purpose of the

bypass bus is just like a back up or a standby bus which operates only when there is a problem in

any one of the bus.

Since unit number 1 is under maintenance at the present moment hence only the main bus 2 is

charged and operational.

9.2) Single line Diagram of 220 kV Switchyard

24

FIG-12 SINGLE LINE DIAGRAM OF 220 KV SWITCHYARD

9.3) OPERATION:

25

To understand the operation we need to go step by step with the single line diagram, Here we are

considering the unit 2 and hence that the GT 2 is operating. The generating transformer 2 steps

up the voltage to the value of 220 KV. Then it is taken to the bus but first there are two more

equipments attached in between. First is a CCVT used for the purpose of synchronization and

then a CT/PT is connected in series in order to measure that the appropriate amount of values of

current and voltage are passing through. After that comes the operation of the isolators.

9.4) THE 132KV SWITCHYARD:

The 132 KV switchyard has the same exact components as the 220 KV line leaving aside the

fact

that it has a different operating voltage. For the operation at this voltage there needs to be a

stepping down of the voltage. This is done by an INTER BUS TRANSFORMER (IBT).

INTER BUS TRANSFORMER:

The inter bus transformers are three winding transformers that can do both jobs of stepping up or

stepping down for the transmission at a different value. The IBT in KBUNL plant are used for

the purpose of transforming the voltage from 220/132 KV. The transformer specifications are as

follows:

Manufactured by BHEL Bhopal.

Three phase, Three Winding.

Oil Temperature Rise 50 degree c

Winding Temperature rise 55 to 60 degree c.

Type of cooling-Oil cooled

HV LV TV

MVA rating = 100 50 30 MVA

KV rating = 220 132 33 KV

Frequency = 50 HZ

CHAPTER:10

26

COMPONENTS IN SWITCHYARD

10.1) CURRENT TRANSFORMERS:

The current transformers are used for the instrumentation and protection. It consists of a single

winding in secondary. The direction of current in the C.T is opposite to the direction of current

in the supply.

FIG-13 CURRENT & POTENTIAL TRANSFORMERS

10.2) POTENTIAL TRANSFORMERS:

The potential transformers as the name suggests are used for measuring the values by the use of

stepping down the power and hence used for protection and instrumentation

.

10.3) WAVE TRAP:

The wave traps are basically used for communication purposes. This is done by increasing the

usual operating frequency from 50 Hz to 50 MHz.

FIG-14 WAVE TRAP

27

Hence as the lines travel between the plant and the load centres, a direct communication can be

established between the various grids without the use of regular telephone lines.

10.4) SURGE ARRESTERS:

Surge arresters are employed at every step in the switch yard in order to protect the equipment

from lightening strokes.

Specifications are as follows:

Max. Voltage=216KV

Max. Current= 10 A

10.5) LINE TOWERS:

The line supports used for transmission are called as transmission tower. The two types of tower

that we found in KBUNL plant were:

(a.) SINGLE LINE TOWERS for 132 KV line

(b.) DOUBLE LINE TOWERS for 220 KV line

10.6) LINE ISOLATORS:

It usually works on no load condition and separates a circuit from the rest of the healthy part for

either fault clearance or maintenance.

FIG-15 ISOLATORS

Types of lines isolators used are:

(1.) S&S made, double break, 1250 A (220 KV bus)

(2.) S&S made, double break,800 A (132 KV bus)

28

10.7) CIRCUIT BREAKERS:

They are used for operation on no load conditions and hence trip the circuit in any case of

failure. These are of oil, vaccum & SF6 operated.

FIG-16 CIRCUIT BREAKER

Specifications are given as under:

(1.) Siemens type 3AS2, 245 KV, 2000 A

SF6 type, for 220 KV bus.

(3.) Siemens type 3AS2, 145 KV , 1600 A

SF6 type for 132 KV bus.

10.8) GUARD RING:

It is basically a bunch of round wire used for safety purpose of humans and animals. It also

avoids accidents and failure of line.

10.9). INSULATORS:

The insulators used in KBUNL plant are of three types:

(a.) PIN INSULATORS (up to 33 KV)

(b.) STRAIN INSULATORS (up to 11 KV)

(c.) SUSPENSION INSULATORS (each disc designed for low voltage up to 11 KV).

29

CHAPTER:11

LOAD CENTRES

11.1) LOAD CENTRES UNDER 220 KV LINE:

a) Darbhanga 1

b) Darbhanga 2

c) Gopalganj I

d) Gcpalganj 2

e) Kafen 1

f) Kafen 2

11.2) LOAD CENTRES UNDER 132 KV LINE:

a) Motihari

b) Bhagalpur 1

c) Bhagalpur 2

d) Samastipur 1

e) Samastipur 2

NOTE: According to the agreement with the power grid corporation of India limited the

KBUNL can draw power from the Kafen power grid when it requires power initially for

generation purposes. The total power distributed by KBUNL is 180 M W and as it has a

generation capacity of 110 MW presently hence it is allowed to draw power from the Kafen grid

to fulfill power requirements.

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CHAPTER:12

GRID CONTROL ROOM

The control room, in case of remote control, houses all the necessary measuring instruments for

each panel or alternator and feeder, synchronizing gear, protective gear, automatic voltage

regulator, communication arrangement etc. A separate battery room and a motor-generator set or

a rectifier is also installed for supplying to make and trip circuit of switchgear. In case of outdoor

switch gear normally compressed air is used for operation.

FIG-17 CONTROL ROOM

The supply and receiving of power as well as the health of various transformers and automatic

control of the equipment is done from this place. A monitoring engineer is specially placed there

to take the various readings of power meters to the load centers.

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CONCLUSION

I hope this project would provide some knowledge and at the same time would be entertaining

national thermal power plant in Kanti, Muzaffarpur gives the insight of the real instruments

used. There are many instruments like transformer, CT, PT, CVT, relay, bus bars, insulator,

isolators, control room etc. What is the various problem seen in thermal plant while handling this

instruments

To get insight of the switch yard, control room how things operate, how things manage all is

learned there. Practical training as a whole proved to be extremely informative and experience

building and the things learnt at it would definitely help a lot in snapping the future ahead a

better way.

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REFERENCES

1. Manual of NTPC Kanti.

2. B. R. Gupta, (2008) "Generation of Electrical energy" Eurasia Publishing House (Pvt.)

Ltd. page 109.

3. http://en. Wikipedia. org/wiki/Alternator

4. http://en.wikipedia.org/wiki/Transformer

5. http://www.google.co.in/imgres?imgurl=http://www.osha.gov/SLTC/etools/

electric_power/images/condenser

6. http://www.mvcircuitbreaker.com/pro.asp?id=145&Cid^l 09

7. Power System Protection and Switch Gear:- B. Ravindranath & M.Chandra, New Age

International (P) Limited Publication, Third Edition (2005), Pg No. (100-150)

8. www.wikipedia.org/wiki/insulators

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