kepko final report

8/13/2019 KEPKO Final Report

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Chapter 1

Introduction

1.1 History:

PAKISTAN is one of the developing countries, where always remaining the

deficiency of the power like those of other developing countries, so for this

purpose KOT A! T"#$%A& PO'#$ STATIONpro(ect was initiated in )*+

-y 'APA with the purpose to fulfil the increasing demand of electricity in

PAKISTAN. Installing the latest technology completed this power pro(ect. In )**/

following the policy of privatisation 0#NA1I$ 2O3#$N%#NT privatised this

power station. NATIONA& PO'#$ 4a !K -ased company5 gave the highest -id,

a-out $S 6+ -illion to purchase 7/8 shares of this powerhouse. Thus a

company named KAP9O -ecame the owner of this thermal station -ecause

according to the contract the management of this organisation was transferred to

KAP9O. &ater on KAP9O purchased ):8 more shares from 'APA. SO now

KAP9O is having ;/8 shares of this powerhouse with total management control.

1.2 About The Project:

Kot Addu is situated in istrict %uisting

PA$9O facility for transportation of "S from Karachi to %ehmood Kot, which is

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a-out ;6 km from Kot Addu. ?rom %ehmood Kot, a ): inches pipeline has -een

laid to this power station and "S pumping was started in @une )*+*.

Sweet under ground water.

?uture load centre of Northwest areas.

Possi-le use of 2as from near-y hodak field.

Kot Addu (unction railway station.

To provide (o-s opportunities to the locals.

2eneral uplift and development of areas.

1.4 About The Plant:

The gas tur-ines, despite of their low installation cost, easy and speedy erection

and high rate, perhaps could not win the deserving popularity over the steam

tur-ines due to the poor efficiency. In the conventional gas tur-ine unit,

su-stantial amount of heat energy was lost through the tur-ine e>haust gases,

which leave the tur-ine at a-out 6+: degree centigrade. To make use of this

wasteful energy, an innovative concept of the com-ined cycle plant, now has

-een introduced -y the gas tur-ine manufacturers. !nder this design, the

e>haust of the gas tur-ine is made to pass through a conduction type -oiler. The

high=pressure steam so generated is then used to run the steam tur-ine, which

thus produces power without any fuel.

This raises the plant efficiency to nearly 78 against the 7+8 of the conventional

gas tur-ine. 2enerally a com-ined cycle plant comprises of two gas tur-ines and

one steam tur-ine. ?or relia-ility of machines, each gas tur-ine is provided with

e>haust gases control dampers. These dampers lead the got gases into the

-oiler or to the atmosphere as per operation mode of the machine. 'ith this

provision, the gas tur-ine can -e run in single cycle mode if the associated steam

tur-ine is under maintenance or unavaila-le due to some other reason.

1. !"er"ie#:

There are many different types of power plants including thermal power plantsand hydel power plants. Thermal power plants -urn fuel such as 2as, "S,?urnace Oil or nuclear fuel to produce heat energy that is converted to electricalenergy through a series of intermediate processes. "ydel power plants convertthe potential energy of water to electrical power as it flows from higher to lowerelevations.

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The BtraditionalB thermal power plant is the $ankine cycle plant, named after theman who invented the cycle. A power plant cycle is a series of processes in

which a fluid, generally waterCsteam, is used to convert heat energy tomechanical energy. The $ankine cycle in its simplest form consists of a -oiler, atur-ine, a condenser, and a -oiler feed pump. #arly plants had thermal

efficiencies of appro>imately 768 to ;:8. Only 768 to ;:8 of the heat energy inthe fuel -urned in these plants was converted to electrical energy. The rest waslost in various ways.

The $ankine cycle has -een refined considera-ly over the years and made moreefficient -y the addition of components like #conomi


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Chapter 2

An Introduction To All $loc%s:&

CC' 1

Block 1

CC' 2

Block 2

CC' 3

Block 3

2.1 Plant (esi)n (ata !* $loc% + ,1:

2.1.1 -as Turbines ,1 ,2:

%anufacturer Siemens 42ermany5

%odel 3 *.7

Starting evice 2en runs as %otor

Starting time upto ;::: rpm min

Tur-ine Stages

?lue gass mass flow 7/ kgCsec

9ontrol Iskamatics

9apacity I9 *6 %'

2.1.2 -as Turbines ,3 ,4:

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%anufacturer ?IAT %CS 2I# 4Italy5

%odel T2 6:

Starting evice ))K3E)*)6K'

Starting time upto ;::: rpm 76 min

Tur-ine Stages

?lue gass mass flow ;77 kgCsec

9ontrol 9onventional relay type

9apacity I9 +7 %'

2.1.3 Stea/ Turbines ,0 1,:

%anufacturer A00 42ermany5

%odel K7:6/

$ated Power ))7.7 %'

3accume :.:*) -ar

"P Steam inlet pressCTemp .* -ar C *6 9

&P Steam inlet pressCTemp ;.;* -ar C )*:./ 9

9apacity I9 ST2 F :* +7 %'

9apacity I9 ST2 F ): * %'

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2.2 Plant (esi)n (ata !* $loc% + ,2

2.2.1 -as Turbines , To ,:

%anufacturer A&ST"O% 4?rance5

%odel %S *::) #

Starting evice /./K3E):::K'

Starting time upto ;::: rpm ): min

Tur-ine Stages ;

?lue gass mass flow :/ kgCsec

9ontrol %ark Speedtronic

9apacity I9 2T F :6 * %'

9apacity I9 2T F :/ +7 %'

9apacity I9 2T F : %'

9apacity I9 2T F :+ * %'

2.2.2 Stea/ Turbines 11 12:

%anufacturer $AT#A! 4?rance5

%odel 3#2A 7:*=)):0

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$ated Power ):;. %'

3accume :.:*) -ar

"P Steam inlet pressCTemp : -ar C 6): 9

9apacity I9 ST2 F )) / %'

9apacity I9 ST2 F )7 +7 %'

2.3 Plant (esi)n (ata !* $loc% + ,3

2.3.1 -as Turbines 13 14:&

%anufacturer SI#%#NS 42ermany5

%odel 3=*.7

Starting evice 2en runs as a %otor

Starting time upto ;::: rpm min

Tur-ine Stages

?lue gass mass flow ) kgCsec

9ontrol T#P#$%

9apacity I9 2T F :6 ):/ %'

2.3.2 Stea/ Turbine 1:&

%anufacturer SI#%#NS 42ermany5

%odel :;:=)/ , N;: G 7H6 G + *

$ated Power )+./ %'

"P Steam inlet pressCTemp 6 -ar C 67+ 9

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&P Steam inlet pressCTemp 6.+ -ar C 77) 9

9apacity I9 ST2 F )6 )7: %'

Chapter 3

Turbine Side

As we are using com-ined cycle in our power station, we will discuss it first then

will move forward a-out a little -it description of each part.

3.1 Introduction to Co/bined Cycle Po#er -eneration:

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9om-ine cycle refers to a power plant in which a gas tur-ine is integrated with a

steam tur-ine cycle unit.The rankine cycle makes use of the much of the

heat in the gas tur-ine e>haust gases. Thermodynamically,the com-ined

cycle can -e represented -y (oining the high temperature 0rayton cycle with

the moderate pressure and temperature $ankine cycle.

Fig Process of GTPS

3.2 hy co/bined cycle is pre*erable:&

One of the principal reasons for the popularity of the com-ined cycle power

plants is their high thermal efficiency. 9om-ined cycle plants with thermal

efficiencies as high as 678 have -een -uilt. 9om-ined cycle plants can

achieve these high efficiencies -ecause much of the heat e>haust from the

gas tur-ine4s5 is captured and used in the $ankine cycle portion of the plant.

The heat from the e>haust gases would normally -e lost to the atmosphere in

an open cycle gas tur-ine.

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Another reason for the popularity of com-ined cycle plant is that it reDuires

less time for their construction as compared to a conventional steam power

plant of the same output. Although it takes longer time to -uild a com-ined

cycle plant than a simple gas tur-ine plant

3.3 Co//on uels sed In Co/bine Cycle:&

Natural gas is the most common fuel used -y com-ined cycle gas tur-ine power

plants. At KAP9O three fuels are used

2as

"S4"igh speed diesel5

?urnace Oil

3.4 The -as Turbine 5$rayton6 Cycle:&

The ma(or component of the com-ine cycle power plant is the gas tur-ine.In

installation where the gas tur-ine e>hausts directly to the atmosphere, it is said to

-e operating in Jopen cycle mode. 'hen a gas tur-ine e>hausts into a heat

recovery steam generator 4"$S25 the resultant steam is used to operate a

steam tur-ine generator, the plant is referred to as a com-ined cycle power plant.

A common arrangement of a gas tur-ine driving an electric generator is shown in

figure. The -asic gas tur-ine consists of a compressor, a com-ustion cham-erand a tur-ine. The air is drawn into the compressor, which raise the pressure.

The temperature also increases with compression and may -e as high as ;6:9

at the compressor discharge.

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Fig Gas Turbine

In the com-ustion cham-er , fuel is in(ected into the compressed air and is-urnt to convert the fuelLs chemical energy into heat energy. 0urning the fuelresults in a high temperature and high pressure gases with considera-le thermalenergy.These hot gases enter the tur-ine where they e>pand ,giving up theirthermal energy to the -lades of the rotating tur-ine.In the process of e>pandingand cooling through tur-ine ,the thermal energy of gas is converted intomechanial energy that is used to do work.A large of work from the tur-ine ,a-out/:8 is used to drive the compressor .The remaider of the tur-ine work is availaleto produce power -y driving a generator.The e>haust temperature of unit )M7 is

in the range of 6:9 to 66:9.

Fig Gas Turbine Rotor

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3.4.1 7ain Co/ponents !* -as Turbine:

). 9ompressor Assem-ly

7. ?lame Tu-e

;. 0urner. %i>ing 9ham-er6. Tur-ine/. Tur-ine shaft. #>haust iffuser

Fig Gas turbine Parts

3.4.1.1 Co/pressor

The a>ial=flow compressor consists of the rotor and the enclosing casing.Included within the compressor casing are the inlet guide vanes, the ) stages of

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rotor and stator -lades and the e>it guide vanes. In the compressor, air isconfined to the space -etween the rotor and stator -lades where it iscompressed in stages -y a series of alternate rotating and stationary airfoil=shaped -lades.

The rotor -lades supply the force needed to compress the air in each stage and

the stator -lades guide the air so that it enters in the following rotor stage at theproper angle. The compressed air e>its through the compressor discharge casingto the com-ustion cham-ers. Air is e>tracted from the compressor 6thstage for-earing sealing and from ))th stage for pulsation control. Since minimumclearance -etween rotor and stator provides -est performance in a compressor,

parts have to -e made and assem-led veryaccurately.

a6 Co/pressor 'otor:

The compressor rotor is an assem-ly of)6 individual wheels, two stu-=shafts,

each with an integral wheel, a speedring, tie -olts and the compressor rotor-lades. #ach wheel and the wheelportion of each stu-=shaft have slots-roached around its periphery. The rotor-lades and spacers are inserted intothese slots. Selective positioning of the

wheels is made during assem-ly toreduce -alance correction

b6 Co/pressor Stator:

The stator 4casing5 area of the compressor section is composed of four ma(orsections

inlet casing

forward compressor casing

aft compressor casing

compressor discharge casing

These sections, in con(unction with the tur-ine shell and e>haust frame form theprimary structure of the gas tur-ine. They support the rotor at the -earing points

and constitute the outer wall of the gas=path annulus.

Inlet Casin)

The inlet casing is located at the forward end of the gas tur-ine. Its primefunction is to uniformly direct air into the compressor. The inlet casing also

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supports the no.) -earing housing a separate casing that contains the )-earing.

Fig Inlet Casing

or#ard Casin)

The forward compressor casing contains the first four compressor stator stages

.

c6 Co/pressor 'otor $lades

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The compressor rotor -lades are airfoil shaped and designed to compress airefficiently at synchronous speed. The -lades of first eight stages are attached totheir wheels -y dovetail arrangements. The compressor stator -lades are alsoairfoil shaped and are mounted -y similar dovetails into ring segments. Thestator -lades of the last nine stages and two e>it guide vanes have a sDuare

-ase dovetail that are inserted directly into circumferential grooves in the casing.&ocking keys also hold them in place.

Fig Comressor Rotor

3.4.1.2 Co/bustion Section

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The com-ustion system is of the reverse=flow type with ) com-ustorsarranged around the periphery of the compressor discharge casing. Thissystem also includes fuel no


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a6 Co/bustion rapper:

The com-ustion wrapper forms a plenum in which the compressor dischargeair flow is directed to the com-ustors. Its secondary purpose is to act as asupport for the com-ustorLs assem-lies. In turn, the wrapper is supported -ythe compressor discharge casing and the tur-ine shell.

b6 Co/bustors:

"isc#arge air from t#e a$ial%flo&comressor flo&s into eac# combustion flo&

slee'e from t#e combustion &raer (see

figure). T#e air flo&s ustream along t#eoutsi*e of t#e combustion liner to&ar* t#e

liner ca. T#is air enters t#e combustor+s

reaction ,one t#roug# t#e fuel no,,le s&irlti- t#roug# metering #oles in bot# t#e ca

an* liner an* t#roug# combustion #oles in

t#e for&ar* #alf of t#e liner.

T#e #ot combustion gases from t#e reaction

,one ass t#roug# a t#ermal soaking ,onean* t#en into a *ilution ,one ere

a**itional air is mi$e* &it# t#e combustiongases. etering #oles in t#e *ilution ,one

allo& t#e correct amount of air to enter an*

cool t#e gases to *esire* temerature. /long

t#e lengt# of t#e combustion liner an* in t#eliner ca are oenings ose function is to

17

Combustor Liner GT 5-8To Co'er

Tie Bolt

Terminal

0$tension

Sring

Cylin*er

. (11 mm)

Stroke

Retaining 4ut

5ock Plate

Insulator

Gasket

Piston 6 Ro* /ssembly

Sark Plug !as#ers

Core /ssembly

07ual Gas

&it#in 8.81

(8.2 mm)

8.8 (1.39 mm)8.888 (8.88 mm)

Figure CI-40Spark Plug Assembly


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ro'i*e a film of air for cooling t#e &alls of t#e liner an* ca as s#o&n in figure.

Transition ieces *irect t#e #ot gases from t#e liners to t#e turbine no,,les. /ll 1

combustion liners- flo& slee'es an* transition ieces are i*entical.

c6 Cross*ire Tubes:

All fourteen com-ustors are interconnected -y means of crossfire tu-es.Once a flame is esta-lished in one com-ustor, the difference of pressuree>isting -etween a fired com-ustor -asket and an unfired one, is enough tocause a temporary flame through the crossfire tu-e which fires the com-ustor-asket unfired.

d6 Spar% Plu)s:

9om-ustion is initiated -y means of the discharge from two high=voltageretracta-le electrode spark plugs installed in ad(acent com-ustors no. )7 and);. These spring=in(ected and pressure=retracted plugs receive their energyfrom ignition transformers at ); K3. At the time of firing, a spark at one or-oth of these plugs ignites the gases in a cham-er the remaining cham-ersare ignited -y crossfire through the tu-es that interconnect the reaction


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tur-ine electronic control circuitry where au>iliary relays in the tur-ine firingtrip circuit, starting means circuit, etc. shut down the tur-ine. The J?ailure to?ire or J&oss of ?lame is also indicated on the annunciator. If a loss of flameis sensed -y two flame detector sensor, the control circuitry will cause anannunciation only of this condition.

*6 uel 8o99les:

#ach com-ustor is eDuipped with a fuel no


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Fig Fuel 4o,,le

3. The Stea/ ater 5 'an%ine 6 Cycle

A simple $ankine 9ycle consists of only four components

The -oiler 4often called a steam generator5,

A tur-ine,

A condenser

A -oiler feed pump.

The efficiency of conventinal steam power plants is a-out ;:8 to ;68 . Actualsteam power plants are considera-ly more comple than the simple cycle asshown in figure. 0ecause the components such as #conomiser,&PM"P ?eed

water heaters,Air preheater are added to improve efficeincy.Typically only +68 to

*:8 of the heat energy input is a-sor-ed in -oilers.This means tat the -oiler isonly +68 to *:8 efficient.

The $ankine 9ycle used in conventional steam power plants can -e representedon a T=S diagram. As with the 0rayton 9ycle, each line segment corresponds toa process in the cycle.

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0oiler is shown with a superheater, thus the steam entering the tur-ine is a-ovesaturation temperature.

Fig > Gra# :f Rankine Cycle

i. Issentropic ;pention5Stea/ Turbine6

The working fluid is pumped from low to high pressure, as the fluid is a liDuid atthis stage the pump reDuires little input energy.

ii. Isobaric Heat 'ejection5Condenser6

The high pressure liDuid enters a -oiler where it is heated at constant pressure-y an e>ternal heat source to -ecome a dry saturated vapor.

iii. Isentropic Co/pression5Pu/p6

The dry saturated vapour e>pands through a tur-ine, generating power. Thisdecreases the temperature and pressure of the vapor, and some condensationmay occur. The output in this process can -e easily calculated using the#nthalpy=entropy chart or the steam ta-les.

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i" Isobaric Heat Supply5$oiler6

The wet vapour then enters a condenser where it is condensed at a constanttemperature to -ecome a saturated liDuid.

In an ideal $ankine cycle the pump and tur-ine would -e isentropic, i.e., thepump and tur-ine would generate no entropy and hence ma>imipansion in the tur-ine, which reduces the energy removed -y the condensers.

3..1 Stea/ Turbine

The tur-ine converts the thermal and kinetic energy of the steam into rotationalmechanical energy. ST=)6 has 7/ stages of "P and +Q+ stages of &P tur-ineand their sealing steam system. There are two types of tur-ine -lades, Impulseand $eaction types. Normally, tur-ine consists of com-ination of impulse andreaction types. The main steam flows to the steam tur-ine which drives the aircooled generator of ma>. )6 %3A .The steam tur-ine is designed as a single =shaft machine with separate "P and &P sections. The "P section is a single flowcylinder and the &P section is a dou-le flow cylinder. Tur-ine -ypass system is to

dump the e>tra steam in the condenserduring start up and steam unloadingconditions.

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Fig Steam turbines

3..1.1 I/pulse Turbine :

The -asic idea of an impulse tur-ine is that a (et of steam from a fi>ed no


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3..2 Heat 'eco"ery Stea/ -enerator

The "$S2 is -asically a heat e>changer composed of a series ofeconomiser,evaporator and super heater sections.These sections are positionedfrom gas inlet to gas outlet to ma>imihaust gases.The heat recovered in the "$S2 is used to supply steam to thesteam tur-ine at the proper temperature and pressure.In open cycle mode of operation,the temperature of e>haust gases of unit ) and

7 leaving KAP9O is 6:9 to 66:9. "igh temperature gas represents a source

of heat energy,some of which can -e recovered if the means to do are availa-le.0y recovering some of this waste heat,the output and the efficiency of a powerplant is increased.The function of heat recoThe function of heat recovery steam generator 4"$S25is to recover the waste heat availa-le in these e>haust gases and transfer that

waste heat to water and steam.The heat is used to generate steam at high

pressure and high temperature.The steam is then used to generate additionalpower in a steam tur-ine driven generator.The "$S2 provides the critical link-etween the gas tur-ine and the rankine cycle in a com-ined cycle plant. The"$S2 is a key component in com-ined cycle efficiency.

3..2.1 HP section:

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The "P section consists of #conomiser, #vaporator, and 9irculation system foreconomiser and evaporator and Super heater.

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e.g. during start up, load variations etc. Additional it has to produce steam of aspecific Duality, which means of correct pressure and temperature which variesagain with the different operation modes and load conditions. The "P=systemgenerates steam at /: -ar I 6;: R9 from the thermal energy contained in the 2Te>haust gas.

3..2.

it from the tur-ine. 3acuumpump regularly runs to evacuate any air accumulation in the condenser.

3..3.1 Condensate Tan%:

One condensate storage tank for controlling the water level is provided. Thecondensate is further deaerated in the feedwater tank to the specified o>ygencontent

3..3.2 Condensate Pu/p:

0oth the e>haust steam and the -ypass steam are condensed -y means of awater cooled -o> type condenser.9ondensate pumps take suction from the condenser hot well and dischargethrough the gland steam condenser and the &P=preheater to the feedwaterstorage tank

Chapter 4

The lectrical Section

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4.1 The -enerator :Synchronous generator or alternator is used to convert mechanical energy intoelectrical energy. ItLs working principle is as follows

4.1.1 or%in) principle:

According to ?areadayLs law of electromagnetic inductionJIf there is a relative motion -etween conductor and magnetic field, thenan #%? will -e induced into the conductor.

To create this relative movement, it doesnLt matter weather the magnet is rotatingand the conductor is stationary or weather the conductor is moving and magnetis stationary.

The magnitude of the induced #%?

is directly proportional to the No ofconductors 4N5 and the rate ofchange of magnetic flu> crossing theconductors.

# N 4dCdt5

4.2 (i**erence bet#een AC )enerator and (C )enerator:

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There is one important difference -etween an A9 and 9 generator. In 92enerator the armature rotates -ut the field system remains stationary -ut in A9generator the case is reverse -ecause here armature remains stationary -ut field

winding rotates.The general thing to keep in mind in this reference is that armature is a thing

which produces alternating magnetic field. So in 9 this magnetic field is -eingproduced -y rotor which is called the armature and in A9 this remains stationaryand here it is called the stator.The stator consists of a cast iron frame which supports the armature core havingslots on its inner periphery for housing the armature conductors. In a slip ringinduction machine the rotor winding terminals are coming out and then they aresupplied with a 9 supply to produce the stationary magnetic field which isconverted into the rotating magnetic field -y rotating the rotor -y an e>ternalsource which is called the prime mover.'hen the rotor rotates, the stator conductors are cut -y magnetic flu>, hencethey have an induced #%? produced in them. As magnetic poles are alternately

N and S, they induce an #%? and hence current starts flowing in armatureconductors, which first flows in one direction and then in the other. "encealternating #%? is produced in the stator conductors whose freDuency dependson the No of N and S poles moving past a conductor in one second and itLsdirection is given -y ?lemingLs right hand rule

?irst fingerUUUUUUUU..%otion of the conductorSecond fingerUUUUUUU.irection of currentThum-UUUUUUUUUUirection of #%? induced

4.3 hy #e use stationary ar/ature@

The advantages of having stationary armature and a rotating field system are). The output current can -e led directly from fi>ed terminals from the stator

to the load circuit without having to pass it from -rush contact.7. It is easier to insulate stationary armature winding for a high A9 voltage

which may have a high value as ;: kv or more.;. The sliding contacts 4slip rings5 are transferred to the low voltage, low

power 9 field circuit which can therefore -e easily insulated.. The armature winding can -e more easily -raced to prevent any

deformation -eing produced -y the mechanical stress set up as a result ofshort circuit current and the high centrifugal force.

(ata sheet:

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Type of generator ; G phase

Type of winding VV

esigned for freDuency 6: "changer which cools the air in thegenerator.

?our identical coolers are provided. The stator end shields contain the verticallymounted coolers. The cooler section is solidly -olted to the upper half of thestator end shield. All four coolers are parallel connected on their water side. ThereDuired cooling water flow depends on the generator output and is ad(usted -ycontrol valves on the hot water side.

i"6 Ad"anta)es o* hydro)en coolin) syste/:

). 'indage losses of the rotor turning are only )8 of those in air.7. The higher thermal conductivity of "ydrogen allows generator to

develop 768 more output than those of air.;. "ydrogen increases the life of generator -ecause of the a-sence of

O>ygen.. The X of generator can -e taken as *+8 with air cooling and **8 with

hydrogen cooling.

"6 (ra#bac%s o* Hydro)en coolin):

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). 2enerator -ody must -e gas tight.7. Special type of oil seal is used on the -earing to stop the leakage of

"ydrogen.;. Precaution should -e taken to prevent any air leakage into the

machine.. A mi>ture of air and hydrogen inside the machine casing is risky and

may cause in e>plosion.

"i6 Stator coolin):

The magnetic core is cooled -y the air flowing through the radial vent ductsunder the action of the fans. The vent ducts are formed -y splitting up the core,along itLs whole length into packets separated from each other -y radial spacer

ri-s. 9ore cooling is thus of radial type.The current flowing through the stator winding creates heat losses which

is escaped to the core due to close contact -etween the winding and core. Thisis called indirect cooling. The end winding area is cooled circulation of air.

"ii6 'otor coolin):

The main rotor heat losses occur in the field winding. It is dissipated -y directcontact with air flowing through the coil. The slot portion of the winding is cooledcirculating air.

All rotor winding is su-divided into four cooling


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Chapter

The Trans*or/er

.1 or%in) Principle !* The Trans*or/er:

A transformer is a static piece of apparatus -y means of which electric power inone circuit is transformed into the electric power of the same freDuency inanother circuit. It can raise or lower the voltage in a circuit -ut with acorresponding increase or decrease of the current. The overall power remainssame to the -oth sides of the transformer.

The -asic working principle of the transformer is the mutual induction -etweentwo circuits linked -y a common magnetic flu>. Simply it consists of two inductivecoils which are electrically separated -ut magnetically coupled with each other.

If one coil is connected to an A9 source, an alternating flu> is setup most ofwhich is linked with the other coil in which it produces mutually induced e.m.f.according to the ?aradayLs &aw of electromagnetic induction. This law statesthat,

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J'hen one coil is placed in such a medium where it faceschange in the flu> then an emf is induced in that coil

%athematically, we can say thate % dICdt

where e Induced voltage% mutual inductancedI rete of change in the currentdt rate of change in time

If the circuit of the second coil is closed, a current flows in it and so in this wayelectric energy is transferred from one coil to the coil. The first coil in whichelectric supply is connected is called the primary coil and other coil to which thepower is supplied is called the secondary coil. In a -rief transformer is a devicethat

Transfers electric power form one circuit to the other.

It does so without change in freDuency.

It accomplishes it -y the electromagnetic induction.

'here two circuits are electrically isolated -ut magnetically coupled.

.2 Trans*or/er construction:

Simple elements a transformer consist of two coils having mutual inductance andlaminated steel core. The two coils are insulated from each other and from the

steel core. Other necessary parts are

Some suita-le container for the assem-led core and winding.

Suita-le insulating medium to provide insulation -etween the core and its

winding from itLs container.

Suita-le -ushing for insulation and -ringing out the terminals of the

winding from the tank.

.3 Types o* the Trans*or/er:

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In all types of transformer, the core is constructed of transformer sheets, steellaminations to provide a continuous magnetic path with minimum air gap.Transformers are classified -y several means

9onstruction wise.

!se wise According to cooling media

According to consumer

0ased upon rating

Or -y some other means.

.3.1 Construction #ise:

9onstructionally, transformers are of two general types.

Shell type.

9ore type.

They are distinguished from each other -y such manner in which the primary andthe secondary coils are placed around laminated steel core.

.3.2 se #ise

Transformers can -e classified according to there use. e.g.

Instrument transformer istri-ution transformer

Power transformer

!nit au>iliary transformer

&ow voltage au>iliary transformer

Start up transformer

Instrument transformers are of very small rating and mostly they are used inappliances. istri-ution transformers are those which are directly connected withthe consumer or which are looked -eside roads or in streets. Power transformersare those which are connected to the transmission lines. They convert powerfrom very lowChigh voltage to very lowChigh current keeping the power same.

.3.3 $ased upon ratin)

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'e can classify them according to there rating. e.g. 7:kva,)::kva,6::kva,):::kva and n the same pattern the others.

.3.4 Accordin) to coolin) /edia

They are classified as,

ry 4Air cooled5

These are used according to the environment temperature and heat dissipation.They are less e>pensive and they reDuire less maintenance. Its maindisadvantage is that itLs output rating decreases -y )amp with an increase of )Yctemp.

.3. Accordin) to consu/er

Transformers are also classified -y means that how a consumers uses it.

Step up trans*or/er

"ere turns of secondary are large then that of primary. i.e. output voltage isgreater than input voltage -ut on the other hand, primary current is large thanthat of secondary.

Step do#n trans*or/er

"ere reverse process takes place than that of the step up transformer.

Generally following type of transformers are used in our power house:

!nit transformer

Start up transformer

Au>iliary transformer

&ow voltage au>iliary transformer

.4 nit trans*or/er

(ata sheet

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The natural cooling of the transformer can -e increased -y the addition of powerfans placed at the -ase or along the side of radiators, whether they are fitteddirectly to the tank or groups in outside gangs.

The fans are of helical type and are of capa-le of generating an air flow.The motor designed for an a-sor-ed power .76 \) "P is closed, self cooling, with

cage rotor and mounted on -earing.Normally the fans are controlled automatically through a thermostate. Inaddition to make manual operation possi-le as well, a preselector is often -uiltinto the system, allowing operation -y means of push -uttons on the protectionand control cover.

'hen forced cooling is provided the power fans unit is split into two unitseach controlled through itLs own switch -y same thermal relay.

7aintenance

Once a month, it is advisa-le to check the operation of the fans and to remove all

traces of drift dust from the fan wheel -lades.The motor -earing do not reDuire any lu-ricant, s this is put into the closedhousing of the -earing at the time of assem-ly.

526 Condenser type $ushin):

The -ushing are packaged in cases, generally in the vertical position. Packing isprovide to protect the -ushing from -lows and moisture during transients.%oreover, the part of each -ushing normally immersed in oil is protected frommoisture -y a cup shaped metal or plastic covering directly fitted to the -ushingflange.

On spare -ushing, not used for transformer testing, a water proof film may -efound for some construction type on the surface of resin paper. 0efore using the-ushing this film should -e removed with a -lunt tool, so as not to damage thesurface underneath.

The -ushing should -e stored in dry place, always in the vertical position, evenfor short period.

536 At/oseal Type air&cell oil conser"ator:

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?or air cell conservator the contact -etween oil and ouside air is prevented.%oreover the pressure on the oil surface remains constant and eDual to theatmosphere pressure.'hen transformer is running, it reDuires a very small maintenance limited toroutine inspection.

In conservator an oil resistant, fle>i-le, ru--er oil=cell is arranged incommunication with the outside through a dreir that prevents condensation in thecell. The air cell gets -igger or smaller so as to compensate oil volumevariations and to keep pressure an oil surface at the atmospheric valve.The

working condition of the 0uchols relays installed on the tank to conservator pipeare not out all affected -y the air cell.

Co/ponents:

). 9onservator designed to allow oil e>pansionfrom =7:9 to *:9.

7. Oil resistant ru--er air=cell;. Silica gel drier on the pipe -etween air=cell and outside air 4in order toavoid that most air enters the cell and forms condensated5.

. On=Off valve on pipe.6. 2ate valve for filter pressure for connection of vacuum pump during

operations./. 2ate valve for eventual vacuum gauge.. 0y pass -etween air cell inside the conservator.+. Overpressure valve.*. Oil level gauge in conservator.):.$emova-le -ottom to allow air=cell assem-ly and conservator cleaning.

)).0uchols relays with On=Off valve)7.9onservaotr drain cock.);.Oil level window.

546 $uchhol9 type )as accu/ulation relay:

This relay is provided for transformer protection when electrical -reakdownoccurs -etween the live parts, or in the event of fault to ground, short circuits-etween turns, phase interruptions, -urning of core, oil leakage in the tank or inthe oil cooling system. This relay will operate on the occurrence of gas formationor on sudden variations of oil level resulting from a-normal transformer

conditions -y actuating an alarm signal and if the fault is serious or persistent, -yputting the transformer out of service.The 0uchhol< relay is installed directly onthe oil pipe connecting the tank to the conservator and is normally flooded withoil, in which itLs inner armature is permanently immersed with the actuatingdevice.The upper contact for signalling purpose is closed -y operation of pertainingfloat, when due to an inflow of gas to the relay or the other reason, the oil levelcontained in the upper part of the relay is lowered.

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The lower contact which controls the tripping circuit, is operated -y thecorresponding float when the oil level reaches the lower part of the relay. Thevane is fitted with an ad(usta-le counterpoise, provided to select the desired oilspeed at which the cooling should occur, thus closing he contact to trip the circuit

-reaker of the transformer.

In the event that an internal fault should occur in the transformer, thee gasdeveloped and collected in the 0uchhol< relay actuates the alarm and trippingcontacts. Thus the speed of gas accumulation and conseDuently the speed ofaction depends upon the e>tent of fault. The alarm and trip contacts are alsoclosed in the event that the oil level should -ecome e>ceedingly low. 'hen thealarm and tripping contacts close, it is necessary to check through the relay

windows the colour and Duantity of gas. 2enerally, colourless gas indicatesdecomposition of paper and card -oard, yellowish gas denotes faults in woodenparts, grey denotes -urning of core and -lack means oil decomposition. In order

to facilitate gas inspection the relay is connected -y means of a pipe to a gascollector located at manLs height. Such device consists of -o> with wide windows,eDuipped with two cocks, -esides the one for the connection to the relay. One ofthem is for gas -reathing and the other is for oil drain.

In order to see weather the gas is inflamma-le , open very slightly the gasdrawing cock and put a flame close to it. If the gas proves not -e flamma-le , thetransformer can -e put again in the service. If no gas comes out of the cock, oreven air is sucked in, the oil is too low. It is always advisa-le to perform achemical analysis of the gas -y means of the gas tester.

'henever the 0uchhol< relay operates the alarm and the trippingcircuit, it is necessary to open the gas drawing cock and to make sure that gas isreleased.

7aintenance

The relay does not reDuire any special maintenance, however, it isrecommended that the operation of float and of alarm and of tripping contacts -echecked at regular interval. ?or this purpose, the relay is fitted with a test device

which may -e Duite different for each type of 0uchhol< relay.

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?

Fig Buc##ol,+s relay56 Air driers

The silica gel drier is fitted on the -reather opening of the oil conservator in eachtransformer, or in the opening of other accessories in which the insulating oil is incontact with the atmosphere. The drier is formed -y a glass vessel with silicagelgrains, the whole -eing enclosed inside a metallic protection container having ametallic protection container having suita-le opening for visual inspection ofsilicagel conditions.

The following types of driers are used generally

Fig 1 with air intrack having a seal for transformer or accessoriescontaining up to /6: liters of oil , with gas pipe threaded connections

.Fig 2with air intake having hydraulic seal for transformers containing up

to *:,::: liters of oil with flange connection.

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Fig 3with threaded lower flange for Nitrogen admission pipe and with filter, with flange connection suita-le for transformers or accessories containing up to*:,::: liters of oil.

!peration

The silica gel is used for the driers is chemically pure silicon o>ide having a veryhigh power of a-sorption, so that a charge may -e renewed at ; to / monthsintervals according to the degree of humidity of am-ient where the transformer isinstalled, to season and to the loading cycles of transformer.

The silica gel is treated with a special coloring su-stance sensitive to thehumidity, so that itLs saturation condition can -e evaluated -y itLs color.

0lue colorUUUUUUUU..9harge is dry3iolet colorUUUUUUUUA-sor-ed humidity is 7: to ;:Y. Pink colorUUUUUUUU.. The charge is saturated with moisture.

In all types of driers the silica gel should have ;.6 to / mm grain si it during heating in order to o-tain a homogeneous drying of whole charge.The charge will -e reactivated when all silica gel grains have acDuired the -luecolor again.

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56 Pressure relie* "al"e

This valve is normally located on the transformer cover or on the wall ofthe transformer tank and has the purpose of providing release of e>cesspressure that may -e produced in the transformer in the con(unction with serious

damage such as an under oil arc produced through -reakage of short circuit.

5B6 Ther/ostat and ther/o/eter

This device is used for the temperature control and consist of a -ul- at the toppart of the transformer tank and connected through the capillary tu-e to a dialindicator.

0esides indicating the temperature, this instrument closed a circuit connected to

an alarm device and su-seDuently a second circuit directly connected to the main-reaker and capa-le to cause the detatchment of the transformer from the line.The measurement system can -e of liDuid thermometer type. The scale is notlinear -ut appro>imately logrethmic e>panda-le with the temperature.

56 Iron and oil te/perature detector

According to the terms of the specifications, the following are installed in thetransformer

One or more thermometric pro-es to measure the coil temperature.

A num-er of thermometric pro-es to measure the temperature of magnetic

core.The oil temperature detectors are directly installed on the cover in the position

indicated in the overall drawing connected to the head of the pro-e the leads tothe terminal -oard of au>iliary service -o>.

The terminals of the iron temperature detectors are -rought outsidethrough appropriate terminal -oard located on the cover from here they too go tothe terminal -oard of the au>iliary service -o>.

(etails o* the detectors are as *ollo#s:

Nickle thermometric resistor Platinium thermometric resistor

$esistance value ):: ohms at :9 $esistance value ):: ohms at :9Temperature coefficient /.)[ ): Temperature coefficient ;.+6[ ):

%a>imum temperature )7: 9 %a>imum temperature )7: 9

506 Current trans*or/ers :

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9urrent transformers are used in power transformers as a source of energy foroperation of relays, to measure the eDuipment of a thermal image plant, a linedrop compensator and protection system etc.

The current transformers normally incorporated in power transformers may -e of

-ushing type with primary winding.The primary is formed -y connection whichgoes from the winding of each individual phase of the transformer to thecorresponding insulator and which crosses the transformer centrally.If the transformer ratio is very low and the accuracy is high, it is advisa-le to usethe type with the primary winding. As far as possi-le, these current transformersare arranged on the machine in an easily accessi-le position.

7aintenance

If the secondary of the transformer is left open, the core may -ecomepermanently magnetiist across the

secondary terminals.The 9.TLs can -e demagnetiamined -y &9$ and also -y99$. 0oth centers are e>amining each and every time the out put voltage of thetransformer, and also noting the reading of -efore and after regulating thevoltage and if there come a condition to change out put voltage they do it -ychanging the tapping. Normally tapping is kept at the place manufactureLs advice.

There are two types of tap changer

). On load tap changer7. Off load tap changer

!n load tap chan)er:

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In this type of tap changer tapping is changed -y keeping the transformerloaded. i.e. the transformer is not -eing isolated for to change the tapping. Thisis done in running condition.

!** load tap chan)er:

In this type of tap changer transformer is made off or disconnected from thesystem and then the tapping is changed. Tap changer is always installed to thehigh voltage side -ecause in this side current is very small and if the current issmall then there will -e very rare chance of producing arcs and if they areproduced, there intensity will -e very small.

5116 arthin) to#ers:

They are installed on each out going phase of transformer. They are there toprotect the transformer winding -ecause during lightning the voltage is increased

to the very high level and it can damage the winding. So -y installing thesetowers, the lightning is -eing earthed.There is a counter on each tower which is counting that how many times lightningoccurred. Such a type of counter is installed on each tower.

5126 ire protection coolin) syste/:

These are special type of no


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7. &ow voltage au>iliary transformer;. Start up transformer. #>citation transformer

All are small transformers as compared to unit transformers. The working

principle and other parts are almost same. The only difference is of there siternal parts are not used insmall transformers."ere is a drawing which is showing the connection -Cw all transformers.

.4.3!"erall /aintenance o* trans*or/ers:

All kinds of maintenance tests are -eing performed at the time of therereDuirement.e.g.

). TT$4transformer turns ratio test57. Oil analysis;. ?ire protection system test. Silica (ell test

Similarly some other important tests are also performed.

Chapter

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The $attery 'oo/s

.1 Purpose?

The purpose of the -attery room is to provoid d.c. supply needed for the relayaction4mostly for protection purposes5.They are also source of e>citation in caseof -lackout thud have vital use as d.c. -ackup supply.

.2 The $attery 'oo/ In nit &1 :

They are two in num-er i.e.one is in 9.9.$ and the other is in the tur-ine hall near the generator.

.3 The $atteries:

They are of the two types w.r.t. the out put voltage

out put voltage of +3

out put voltage of 77:3

They are of led acid type having sulfuric acid 4"7SO5 as the electrolyte.The standard specific gravity of the acid is 1.23 gm/lit. when charged fully.

@. The Conductor:

They are made of copper and are stranded to provide fle>i-ility and heavyeligi-le of carrying ma>imum possi-le current at any condition , minimumresistance for high efficiency and insulated properly to fulfil reDuirements.

Chapter B

S#itch ard

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A Switchyard or Su-station, consisting of large -reakers and towers, is usuallylocated in an area close to the plant. The su-station is used as the distri-ution

center where electrical power is supplied to the plant from the outside, andelectrical power is sent from the plant.

Often there are at least 7 main 3ery high voltages 4typically 77:,::: or );7,:::volts5 are present. 2as and oil circuit -reakers are used. The gas 4e.g. sulfurhe>aflouride5 or oil is used to e>tinguish the arc caused when a -reaker isopened, either -y a control switch or due to a fault %anually or motor operateddisconnects are provided on either side of the -reaker to allow the -reaker to -eelectrically isolated so that maintenance work can -e performed.

B.1 $rea%er Sche/es:

There are usually two schemes

Single 0reaker Scheme

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One and "alf 0reaker Scheme

B.1.1 Sin)le $rea%er Sche/e

In this scheme two circuits 4-us -ars5 share the two -reakers. The scheme isused for );7 k3 or lower switchyards. The main disadvantage of this scheme

whenever we want to work on a -reaker the entire circuit -us -ar should -edisconnected from the generator and feeder sides.

B.1.2 !ne and Hal* $rea%er Sche/e

A method of interconnecting several circuits and -reakers in a switchyard so thatthree circuit -reakers can provide dual switching to each of two circuits 4-us -ars5-y having the circuits share one of the -reakers, thus a -reaker and one=half percircuit this scheme provides relia-ility and operating

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then we can easily recover it -y opening the -reaker. Similarly the line fromthe step=up transformer to the -us -ar is also protected -y a circuit -reaker.

So, this circuit -reaker is a kind of connection and disconnection -etweenthe generator, -us -ar and the transmission line. So, -y this way, thetransmission line or su-station or -us -ar itself and also generator are

protected from any kind of small or -ig accidents.

i6 Co/ponents o* the circuit brea%er

5a6 Au;iliary s#itch

This is only for the purpose of the taking information a-out the working of the9.0. e.g. it consists of P&9Ls which take information that whether the-reaker is open or close.The information a-out the opening and the closing ofthe -reaker is taken -y such a way that there are some Normally open andNormally closed contacts in au>iliary switch. So, if the -reaker is closed theninformation from the Normally closed contacts is sent to 9.9.$. 49entral9ontrol $oom5 and a light is made ON there showing that 0reaker is in closedcondition.Similarly is the -reaker is open, then Normally open contacts are closedand in the similar fashion descri-ed a-ove, light is made ON in 9.9.$.showing that -reaker is in open condition.

5b6 7echanical s#itchin)

This process is done with help of the oil pressure. A certain oil pressure iso-tained and then according to the information supplied -y the manufacturer,opening and closing of the -reaker is done at some pressure defined. i.e. ifpressure goes less than 7; -ars than -reaker is opened and then does notclose itself until it is done manually.

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5c6 Inside protection

As -ecause of the opening and closing of contacts os -y some otherreasons , archs are produced inside the -reaker which are dangerous forthe life and the characteristics of the -reaker. So, these archs must -eDuenched.There are many methods for Duenching these archs. e.g.

Air Duenching

2as Duenching

3acuum Duenching

Now a days, most commonly used methods for Duenching these archs is theuse of the S?/gas which is very much efficient for doing this task.

ii6 Ter/inolo)y !* $rea%er:

'upture Current:

The current at the time of opening operation of the -reaker is called rupturecurrent. It may -e the ordinary regular current value or very large fault currentvalue depending on the condition of operation .

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'upture Current 'atin):

This the ma>imum interrupti-le value of current at the instant ofoperation. This is the ma>imum value of current at which the -reaker cansuccessfully provide protection against re striking of arc.

7a%in) Current:

This is the value of load current at the point of making contacts close

'ated 7a%in) Current?

This is the ma>imum -eara-le current at the time of making the contact .

$rea% Ti/e :

This is the time reDuired to do the -reak operation.

'ated 8or/al Current:

This is the ma>imum amount of current that can -e applied to the -reaker onnormal working conditions for long time without effecting the efficiency ,

without a-normal temperature and without any damage.

'ated 8or/al ?olta)e:

The ma>imum amount of voltage applica-le for long passage of time.

'ated Short Ti/e Current?

This is the ma>imum -eara-le short interval 4second or less5 current that can-e applied to the circuit -reaker.

iii6 Types o* Circuit $rea%er

They can -e classified w.r.t. two criteria w.r.t arc Duenching

w.r.t. construction

w.r.t. arc Duenching media , we have most used types listed -elow

the oil circuit -reakers

the air circuit -reakers

the S?/ circuit -reakers

the vacuum type

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!il Type:

In the oil type ckt -reaker, the arc is produced in the oil thus oil decomposes andreplaced -y the surrounding oil thus provides -oth cooling and give properdielectric strength. Such an arrangement can work for -reaking duty note>ceeding )6:%3A. Addition can -e done to increase the rating -y providing pressure pot ande>ternally generated pressure to e>tinguish the arc -y pushing it and also -ydividing it into sections -y means of insulators .0y these means, a rating of6::%3A at );7 k3 is possi-le. Also low oil content -reaker can -e used todecrease the siial, radial or cross -last is used in these -reakers to e>tinguish arc and alsoinsulators can -e added to increase the dielectric strength.

?acuu/ Type:

In this type, the vacuum is created at the contact position. 'hen the contactsopen, the resistance -ecome very high since no ionitinguished.The S $rea%ers:

They are the -reakers using sf/ gas as the arc Duenching media. They arespecial with compact si


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Fig SF@

i"6 $rea%ers In The S#itch yard !* nit&3:

They have hydraulic type mechanic and are advance. They can -e controlledfrom c.c.r. or from the local control ca-in in the switch yard .They use sf/ as arc

Duenching medium .Since used in one and the half scheme, have isolators at the-oth ends .They get information from p.t. and c.t. for their operating system..There are three -reakers in each -ay. #ach one is manufactured -y

SI78S 5-er/any6The model num-er is3!" 1 .The specifications are as under

1. #ated $oltage 2%&k$2. power fre'. withstand $oltage 1 min 3() * %() k$3. #ated normal current 31&) !%. #ated short time current 1sec+ %) k!&. #ated peak current 1)) k!

(. #ated ,reaking current %) k!-. #ated making current 1)) k!. /reak time (& or &) msec0. inspection after 2) years

The working temperature conditions at Kot Addu are very tough ranging from ashigh as 6:Q in summer to as low as += degrees 9elsius .

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These are used for the protection of the any unit. This is a mechanical deviceand information a-out the opening and closing of the isolator is send to the9.9.$. in the same manner as descri-ed a-ove.

!bjecti"eItLs main purpose is to isolate one unit from the other unit. %ainly two isolators

are used for the protection of -reaker.

.Fig Isolators

536 Insulation Strin)

ItLs main purpose is to provide the insulation -etween the transmission line,su-station, transformer etc.This is such an important device that without it there is not any concept of thetransmission.

Fig Insulating string

546 22, %" D132 %" $us $ar

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77: kv -us -ar is our main -us -ar. This is the line or -us -ar which is connectedto the our national 77: kv -us -ar forming ring main system. This is the line to

which all generator are connected and supplying there power. 'e can take out orin it the reDuired power.Power is delivered to any area only through this -us -ar, -ecause it is (ust like a

see of electrical power in which all rivers 42enerators5 are supplying water4Power5 and some rivers 4Power5 are taking water 4Power5 out of it. ?or e>amplethe load side.

Fig 228 k' Bus Bar

56 Current Trans*or/er

There are five ciols of 9T and three -asic purposes of using 9T.). %easurement of the current.7. Protection of the relays and -reakers etc.;. %etering

And the forth one is. for the 0reaker failure protection.As very high amount of current is flowing through the line so we canLt

measure such a -ig amount of current -y simple ammeters. If we want to designan ammeter for this purpose, then the si


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make the relay isolated from the system with the help of the of the Isolator.Similarly, if -y chance there occurs a fault in transmission line, then it countscurrent and sends information to distance protection relay to operate it earlier

which is nearest to the fault and similarly to send information to the over currentrelay to make itLs operation.

As KAP9O or any generating company is also supplying energy to the'APA, so it is to count that energy which is given to 'APA and to take thecharges from them. So we use 9T for this purpose of metering.

Circuit *iagram of PT Fig PT

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56 Potential trans*or/ers

It is used to measure the voltages and it has -een installed with the -us -ar tomeasure the voltage across the -us -ar. 'e are checking for high voltage and low voltage -ut carefully for thelow voltage -ecause the au>iliaries which we are running from this voltage willdraw very high current if the voltage is very low and this can damage oureDuipment.

So, we keep on checking for the low voltage and the high voltage. 'ehave to use P.T. -ecause we canLt design such a -ig voltmeter.

Circuit *iagram of PT Fig PT

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5B6Auto Trans*or/er

An autotransformer is an electrical transformer with only one winding. The autoprefi> refers to the coil acting on itself rather than any automatic mechanism. In anautotransformer portions of the same winding act as -oth the primary andsecondary. The winding has at least three taps where electrical connections aremade. An autotransformer can -e smaller, lighter and cheaper than a standarddual=winding. transformer however the autotransformer does not provide electricalisolation.Autotransformers are often used to step up or down -etween voltages in the )):=))=)7: volt range and voltages in the 77:=7;:=7: volt range, e.g., to outputeither )): or )7:3 4with taps5 from 7;:3 input.

Fig /uto Transformer

56 Conductors:

Normally we use two conductor scheme for our switch yard to distri-ute the loadof the current in a conductor. This conductor scheme can -e of three or fourconductors -ut such schemes are used for the transmission lines. 'e adoptsuch a scheme to make one conductor cool and to avoid from the -urning of theconductor -ecause one cone conductor may not carry such high amount current.

These conductors are necessary things for to make connections -etweenthe unit transformer and the -reaker similarly -etween the -reaker to the -us -aror even we can say that -etween the -us -ar and the transmission line..

506 Control s#itches:

These are some -ut important -o>es looked inside the switch yard. These areimportant -ecause they are controlling the switching action of the -reaker andmaking connection of the relays to make it operate at the reDuired time. These are also used for the opening and closing of the isolator to makethe connection and the disconnection -etween the two things. 'e can say that

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we are controlling every thing in switch yard -ecause all remaining things aregoing to operate on the -asis of the -reaker and the isolator -ecause these arethe most important and the -asic things in switch yard.

51,6 'elays:

These are operated -y taking information from 9.T. and P.T. #ach and everything of the system even in the switch yard is -eing protected -y relays -ecausethey are made very much sensitive for the faults. They sense every fault for

which it has -een designed and then some other important devices are operatedfrom the signal of the relay.There are many types of the relays

ifferential over current relay.

Over current relay.

Over and under voltage relay. irectional over current relay.

Similarly there are many other types of the relays which we will discuss later.

Chapter

uels Section

.1 Co//on uel sed In EAPC!

Natural 2as

"i Speed iesel 4"S5

?urnace Oil 4?O5

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Fig Fuels Section

.2 Tan% area introduction.

There are twenty seven tanks in the tank farm ,five of them 4,6,/,)) M 7:5 areused for "S storage,eleven tanks 4)7=)* M 76=75 are used for the storage ofuntreated &S?O and remaining eleven tanks4)=;, =): M 7)=75 are used for thestorage of treated &S?O.The capacity of all tanks is almost the same.The suctionheaters of tanks 47)=75 are placed out side the tanks.

Pi) station

this is the station where fuel is received from the pipeline coming from the &al Pirdepot.from Pig station &S?O 4&ow Sulphur ?uel Oil5 and "S are fed to therespective headers for filling the tanks.Initially when pumping of &S?O starts fom&al Pir depot the line is packed with "S.Pig is entered in the line from &al Pir inorder to avoid the mi>ing of two fuels.In this period "S valves are kept

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open.'hen ?O reaches at the comple> the "S valves are closed after checkingthe result of the fuel and valves for feeding the untreated tanks are opened.'hen?O pumping is stopped pig is entered in the line and "S is pumped in the linefor removing the ?O from the line.The pig takes seven and half hours to reach atthe Pig Station.After at the Pig Station ,it is taken out of the line.


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!nits feeding header from tanks.

$etun header from unit.

3. or HS( Tan%s:

?illing header from Pig Station and ecanting Station.

?illing headers for treated fuel from ?OTPs to the treated tanks.

$ecycling headers from ?OTPs.

!nit feeding header from tanks.

$eturn header from unit.

Color Codin) o* the ?al"es:

?or untreated tanks the color coding is as under$ed filling valve0lue ?OTP feeding valveVellow $ecyling valve?or treated tanks the color coding ia as under0lue ?OTOP feeding valveVellow $ecyling valve0rown treated ?O from ?OTP0lack M white common header valve of all units feeding

0lack unit 6=+ feeding valve'hite unit ),7,); M ) feeding valve2reen return valve from units?or "S tanks color coding is same as for treated tanks -ut with yellow strip.

.4 !perations !* Tan%s:

!peration o* untreated tan%s:

?or filling of untreated tanks the filling valve of that tank is opened .In this wayfuel from the filling header is filled to the tank .?or sending the fuel for treatmentto ?OTPs the suction valve of the 0ooster Pumps is opened.The procedure for shifting of fuel from one tank to another is as under

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The discharge valve of the desired tank and 0ooster pump are opened.

The recycle valve of the desired tank is opened.

The shifting valve near tank F +4-lue Cyellow5 is opened.

uring this process all ?OTPs should not operate and also the suction

valve of ?OTPs remain closed.

It should -e checked carefully that the recycle valve of any other tank shouldnot -e opened.he procedure for feeding the FP is as under:

The suction valve to -ooster pump is opened. In this way the fuel is feed

to the header going to feed ?OTP.The inlet valve to ?OTP is opened and

so the fuel is supplied from untreated tanks.

If the result of treatment are not satisfied then there is an option to recyclethe fuel in any of the untreated tank. In this case the divertor valve is

selected to recycle mode and the fuel is recycled to the desired tank.

!peration o* HS( Tan%s:

?or filling of "S tanks from the Pig Station the &S?O filling header valve

is closed and the "S filling header valve is opened. Now the filling valve

of the tank to -e filled is opened.

?or the treatment of "S the 0ooster Pump of the tank is operated and

the valve for feeding ?OTP is opened. The inlet valve of the ?OTP is

opened and after treating the fuel it is fed to the desired tank through

treated from ?OTP via tank filling pipe.

To shift untreated "S from one tank to the other ,the procedure is as

under

The discharge valve of the desired tank and 0ooster pump are

opened.

Open the ?OTP feeding valve.

Open the shifting valve4-lueCyellow5

Open the recycle valve of the desired tank.

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uring this process ?OTP F7 should not -e in service and the inlet

valve should -e closed. At the same time the recycle valve of any

other tank must -e closed.

The shift treated "S from one tank to another tank,the procedure is as under

The discharge valves of the desired tank and 0ooster pump areopened.

Open the valve 4white5 for feeding 2T ),7,);,).

Open the shift valve 4-rownCwhite5.

Open the filling valve 4-rown5 of the desired tank.

uring this process 2T ),7,);,) are unavaila-le on "S.

!peration o* Treated Tan%s:

After treatment of &S?O from the ?OTP it is filled in any of the treated tankthrough the treated header.In case if the Duality fuel of the treated tank is poorthen it fed the ?OTP and from ?OTP it is again fed to the treated tank. Thisprocess is called recycling of the treated tank.?or shifting of the treated &S?O from one tank to another ,the procedure is asunder.

The discharge valves of the desired tank and the 0ooster pump are

opened.

Open the valve of the header for feeding 2T 6=+.

Open the shifting vave

Open the shifting valve of desired tank.

uring this process ?OTP are not service.?or shifting of treated &S?O -etween tank )=; ,the procedure is as under.

The discharge valves of the desired tank and 0ooster pump are

opened.

Open the valve of the header for feeding units 6=+.

9lose the valve of the header for feeding units 6=+ near tank F).

Open the valve connected to the filling line of the tank where ?O is

to -e shifted.

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This is the procedure for shifting the ?O from tank 7 M ; to any of the tanks ),7,M;.0ut for shifting the ?O from tank F) to any one of 7 M ; ,the procedure is asunder

The discharge valves of the desired tank and -ooster pump are

opened.

Open the valve of the header for feeding units ),7,); M ).

9losed the valve of the header for feeding units )6=+ near tank F)

to stop feeding to the units from this section of the header.

9lose the valve of the header for feeding units ),7,); M ) near

tank F ) to stop feeding to the unit from this section of header.

Open the valve of the header for feeding units 6=+. In this way

header for units 6=+ is energi.The ?OTPs ),7,;M are of same typewhile ?OTP=6 is of different type than )stfour i.e. centrifuge type.?OTP =7 is used for the treatment of "S while others are used for the treatment

of &S?O.The purpose for the treatment of fuel is to remove waterGsolu-le salts ofpotassium and sodium from the fuel -ecause the metling point of these salt islow.Therefore when fuel -urn at the high temp. these salt melt and deposit on thesurface of the tur-ine -lades and cause un-alance of shaft.

A brie* introduction to the operation o* !TP51&46

The function and the operation of different parts of ?OTP are descri-ed as underin seDuence.

uel oil circuit

?uel oil is fed to ?OTP -y opening the main feeding valve. The fuel is filteredand then pumped -y the OP pumps.

!P51&26:

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These pumps are used to pump the oil in the economi


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Fig Process *iagram of F:TP

!P 53&46These pumps are used to pump the oil into the ?OTP.

!TP Sta)es

There are three different stage in the ?OTP.The discharge of OP 4;=5 is fed tostage =).'ater coming out of stage=)) and demulsifer are fed to the fuel feeding

line of stage =) -efore mi>ing valve. ?rom stage=) fuel is fed to stage=)). 'atercoming out of stage =))) and demulsifier are fed to the fuel feeding line of stage=)) -efore mi>ing valve. ?rom stage=)) fuel is fed to stage=))) . ?resh water anddemulsifier are fed to the fuel feeding line of stage=)) -efore mi>ing valve .Treated fuel from stage=)))is sent to the treated tanks.Thermal oil is supplied to each stage for heating the contens of the stage.There are two transformer on each stage . The rating of the transformer is::C)*:::v. The high voltage is used to produce dipole moment in the water .

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ue to the creation of dipole moment the dia of the water drop increase.ue toincrease in dia the setting rate of the water drop increase and it settles at the-ottom of the stage .?O having low specific gravity than water comes up .?rom

where it is collected and is discharged from the stage.

P 51&26

These pumps are used to fresh water into stage=))). The discharge of 'P isheated in economiing valve. The ;rdlineis connected to the fuel oil line after the duple> filter. The dosing of demulsifier inany stage depends upon the Duantity of water in that stage . If Duantity of water ismore then demulsifier dosing is increased and vice versa.

locculant (osin).

This chemical is used to separate oil from water . This chemical is stored in?locculant storage tank. %i>ing fresh water in the flocculant dilution tank makesthe diluted solution .The fresh water is pumped in the flocculant dilution tank -ymeans of ?P.'hich works on the level of the flocculant dilution tank. ?rom the

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dilution tank the diluted solution is pumped -y two pumps to AS? and oily waterseparator through three feeding lines.

uel Additi"e Seprator:

?uel oil dosing chemical is stored in this storage tank. ?rom this tank thechemical is sent to the additive=dosing skid through pumps for -eing dosed in thefuel.

!il ater Seprator:

The effluent water is pumped -y water recycling pumps 4'$P ),75 into oilywater separator .'here oil mi>ing in water is separated -y means of "oneycom- package .The flocculent also dosed in the oily water separator feeding line.This assem-ly has small tu-es through which the effluent water passes ,the oil-eing lighter than water comes up through these tu-es and water deposits in the

-ase of the oily water separator tank . The oil separated -y this separator isstored in the sludge tanks . The effluent helps oil drops present in the effluent

water to separator from the water. The water from the separator goes into the Air?lotation !nit.

Air lotation nit:

In this unit the oil still present in the effluent water is removed -y using airflotation techniDue .The flocculent is added in feeding line of water and in the ; rd

stage of A?S. ?our -lenders driven -y motors -lend the effluent water .ue tothis process the oil comes up like -utter and is collected in the oil cham-er ofA?S. ?rom this cham-er oil is pumped and sent to sludge tank. The water ispumped into the pit of pit for the 9T of "$S2s.

kepko final report

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