SEMINAR REPORT 2012-2013

Submitted To:

Head of department

MR. S.N. JHANWAR

Submitted By

YASH SHARMA

GU IDED BY:

MR. R.K. JAIN(AEN.)

FINAL YEAR VIIth SEMESTER

ELECTRICAL ENGINEERING

AT

220kV G.S.S. V.K.I, JAIPUR

FOR 30 WORKING DAYS

FROM 24th MAY TO 29th JUNE

INTRODUCTION INTRODUCTION There are several Sub station b/w generating & final load points. There are several Sub station b/w generating & final load points.

The Sub station should be installed & commissioned to deliver the The Sub station should be installed & commissioned to deliver the power to the distribution network.. These sub station receive power to the distribution network.. These sub station receive power from incoming lines. The power is transformed to design power from incoming lines. The power is transformed to design voltage by the transformer and is then supplied to outgoing lines. voltage by the transformer and is then supplied to outgoing lines. There are may be two or three voltage level in sub station There are may be two or three voltage level in sub station depending upon incoming & outgoing line voltage level.depending upon incoming & outgoing line voltage level.

The electrical sub station design in influenced by following aspects :The electrical sub station design in influenced by following aspects :• Rated voltage of incoming & outgoing lines.Rated voltage of incoming & outgoing lines.• Total MVA to transferred.Total MVA to transferred.• Geographical area available.Geographical area available.• step-up and step-down.step-up and step-down.• Switching sub station Switching sub station • Receiving sub station Receiving sub station • Distribution sub station Distribution sub station • Industrial sub station Industrial sub station • Industrial or outdoor sub station Industrial or outdoor sub station

BUS-BARSBUS-BARSIt is conductor to which a no. of circuit are connected. It is conductor to which a no. of circuit are connected.

In (220kV) G.S.S. there are two bus-bar running In (220kV) G.S.S. there are two bus-bar running parallel to each other, one is main & other is auxiliary parallel to each other, one is main & other is auxiliary bus. The purpose of using two bus is only for stand bus. The purpose of using two bus is only for stand by. In each of failure of one bus we can keep the by. In each of failure of one bus we can keep the supply continue with the help of other bus by using supply continue with the help of other bus by using isolators.isolators.

According to bus voltage the material is used. The most According to bus voltage the material is used. The most commonly used material is Aluminum & copper. But commonly used material is Aluminum & copper. But Aluminum is widely used because of its property & Aluminum is widely used because of its property & feature & it is cheap as compared to copper. feature & it is cheap as compared to copper.

Type of bus-bar system :-Type of bus-bar system :-• Single bus-bar systemSingle bus-bar system• Single bus-bar system with sectionilation Single bus-bar system with sectionilation • Duplicate bus-bar systemDuplicate bus-bar system

BAYBAY

• Bay is a arrangement Bay is a arrangement of the protection and of the protection and metering equipment. metering equipment.

• It have isolator, It have isolator, circuit breaker and circuit breaker and current transformer. current transformer.

• This instrument This instrument arrange between two arrange between two bus-bars. First is bus-bars. First is main bus and second main bus and second is auxiliary bus. is auxiliary bus.

MAIN BUS A

AUXILARY BUS

ISOLATOR

C.T.

CIRCUIT BREAKER

TransformerTransformer A transformer is a static device of apparatus by means of which A transformer is a static device of apparatus by means of which

electric power in one circuit is transferred into electric power of electric power in one circuit is transferred into electric power of the same frequency in another. It can rise up or down the the same frequency in another. It can rise up or down the voltage in a circuit but with the corresponding decrease or voltage in a circuit but with the corresponding decrease or increase in current. The physical basic of transformer is “mutual increase in current. The physical basic of transformer is “mutual induction” but now electric circuit linked by a common magnetic induction” but now electric circuit linked by a common magnetic flux. It is simplest form it consist of induction coil which are flux. It is simplest form it consist of induction coil which are electrically separated but magnetically linked through a path of electrically separated but magnetically linked through a path of low reluctance. low reluctance.

If one coil is connected to a source of alternating voltage in step up If one coil is connected to a source of alternating voltage in step up in the laminated core must be linked with a another coil in in the laminated core must be linked with a another coil in which it produced mutually induced emf .which it produced mutually induced emf .

In brief transformer is a device that transfer the electric power from In brief transformer is a device that transfer the electric power from one circuit to another circuit. It transfer electric power without one circuit to another circuit. It transfer electric power without change of frequency. change of frequency.

It accomplished this by electro magnetic induction where two It accomplished this by electro magnetic induction where two electric circuit are in mutual induction so they are influence of electric circuit are in mutual induction so they are influence of each othereach other..

Basically Basically transformer used in the generation & distribution purpose transformer used in the generation & distribution purpose are divided into tow categories:are divided into tow categories:

A.A. Distribution transformerDistribution transformerB.B. Power transformerPower transformer

Main oil tank

Conservating tank

H.V. Bushing

Tap changing box

Breather

Radiator Cooling fan

L.V. Bushing

Buchholtz relay

BUSHINGSBUSHINGS1.1. BushingsBushings: bushing are : bushing are

made from highly made from highly insulating material to insulating material to insulate and to bringout insulate and to bringout the terminals of the the terminals of the transformer from the transformer from the container. The bushing of container. The bushing of three types:three types:

i.i. porcelain bushing used for porcelain bushing used for low voltage transformer low voltage transformer

ii.ii. Oiled filled bushing for Oiled filled bushing for voltage up to 33kVvoltage up to 33kV

iii.iii. Condenser type bushing Condenser type bushing used for voltage above used for voltage above 33kV33kV

BU

SH

ING

CONSERVATOR TANKCONSERVATOR TANK 1.1. Conservator tankConservator tank:: it is it is

used generally to used generally to conserve the insulating conserve the insulating property of the oil from property of the oil from deterioration and deterioration and protect the transformer protect the transformer against failure on against failure on account of bad quality account of bad quality of oil. Conservator is of oil. Conservator is partially filled with oil. partially filled with oil. Its function is to allow Its function is to allow space for expansion of space for expansion of oil due to heating and oil due to heating and contraction due to contraction due to cooling of oil.cooling of oil.

Main conservator tank

Conservator tank Buchholtz relay

BREATHERBREATHER1.1. Silica gel dehydrating Silica gel dehydrating

breatherbreather: : the breather the breather is used to prevent entry is used to prevent entry of moisture inside the of moisture inside the transformer tank. The transformer tank. The breather consists of breather consists of silica gel. Its also called silica gel. Its also called copper sulfate(CuSOcopper sulfate(CuSO44). ). When air is taken in or When air is taken in or out of the transformer out of the transformer due to contraction or due to contraction or expansion of oil in the expansion of oil in the tank, the silicagel tank, the silicagel absorbs moisture and absorbs moisture and allows the air free from allows the air free from moisture to enter the moisture to enter the transformer.transformer.

Moisture saparator

COOLING SYSTEM COOLING SYSTEM RadiatorsRadiators: in large capacity : in large capacity

transformer above 50kVA and transformer above 50kVA and above, the increase in oil above, the increase in oil temperature is quite high. On temperature is quite high. On account of losses in the account of losses in the transformer, the oil near the transformer, the oil near the windings gets heat and heat up windings gets heat and heat up and its heat dissipation by the and its heat dissipation by the radiators.radiators.

FansFans: : when the natural cooling is when the natural cooling is not sufficient and wdg or oil not sufficient and wdg or oil temperature is increases and oil temperature is increases and oil temperature is above 70 to 75temperature is above 70 to 75ooc c the fans is on automatically and the fans is on automatically and manually. manually.

MotorMotor :when the load on the Xmer is :when the load on the Xmer is instantly high then the instantly high then the temperature of wdg is also temperature of wdg is also increase so motor will on. increase so motor will on.

Radiators Cooling Fans

PROTECTION OF PROTECTION OF TRANSFORMER TRANSFORMER

• Pressure relief valvePressure relief valve:- :- in case of the major faults in the T/r like in case of the major faults in the T/r like short circuit in the winding the internal pressure is build up to a short circuit in the winding the internal pressure is build up to a very high level which may result in rapture of tank to avoid this very high level which may result in rapture of tank to avoid this PRV is provided. PRV is provided.

• Oil temperature indicator:- it is a distance thermometer operated Oil temperature indicator:- it is a distance thermometer operated on principle of liquid expansion. It indicates the top oil on principle of liquid expansion. It indicates the top oil temperature at marshalling box. The connection between the temperature at marshalling box. The connection between the thermometer and the dial indicator is made by steel capillary thermometer and the dial indicator is made by steel capillary tube.tube.

• Winding temperature indicator :- it also operates on principle of Winding temperature indicator :- it also operates on principle of liquid expansion. It indicates the top oil temperature at liquid expansion. It indicates the top oil temperature at marshalling box hot spot temperature of winding. The winding marshalling box hot spot temperature of winding. The winding hot spot of top oil temperature difference is simulative by means hot spot of top oil temperature difference is simulative by means of CT current fed to the heater coil fitted around operating of CT current fed to the heater coil fitted around operating bellows. bellows.

MAINTENANCE OF MAINTENANCE OF TRANSFORMERTRANSFORMER

The general notes and information given under storage, handling and The general notes and information given under storage, handling and installation etc. are applicable to routine maintenance:-installation etc. are applicable to routine maintenance:-

1.1. The oil level should be checked at frequent intervals and any The oil level should be checked at frequent intervals and any excessive leakage of oil investigated. There may be a slight loss of oil excessive leakage of oil investigated. There may be a slight loss of oil by evaporation this need not cause concern if the thank is topped up by evaporation this need not cause concern if the thank is topped up at regular intervals.at regular intervals.

2.2. All miner leaks or sweating should be repaired as quickly as possible.All miner leaks or sweating should be repaired as quickly as possible.3.3. Oil for topping up should comply with clause 2.3.3 and should Oil for topping up should comply with clause 2.3.3 and should

preferable be from the same source as the original oil. Oil from preferable be from the same source as the original oil. Oil from different crude’s may not be completely miscible and may separate different crude’s may not be completely miscible and may separate into layers. Feature, there may be a greater tendency to form acidity into layers. Feature, there may be a greater tendency to form acidity or sludge in a mixture then in an oil from a single source added a or sludge in a mixture then in an oil from a single source added a make up only boot not exceeding about 10.make up only boot not exceeding about 10.

4.4. Samples of oil should be taken at regular intervals and tested.Samples of oil should be taken at regular intervals and tested.5.5. It may be mentioned that the dielectric strength does not give a true It may be mentioned that the dielectric strength does not give a true

indication of the deteriorated condition of the oil. Even an oil which indication of the deteriorated condition of the oil. Even an oil which highly with give a high dielectric strength, if it is dry. Normal method highly with give a high dielectric strength, if it is dry. Normal method of oil purification only maintain the dielectric strength, but do not give of oil purification only maintain the dielectric strength, but do not give indication of the deteriorated condition of the oil, it is, therefore, indication of the deteriorated condition of the oil, it is, therefore, inadvisable to relay solely on the dielectric strength a minimum of inadvisable to relay solely on the dielectric strength a minimum of 60kV r.m.s. across a standard gap (13mm spillers 4mm aparts). 60kV r.m.s. across a standard gap (13mm spillers 4mm aparts).

INSULATORINSULATORTo prevent the flow of current to the To prevent the flow of current to the

earth from support to transmission earth from support to transmission line as distribution line. one all line as distribution line. one all secured to the supporting towers secured to the supporting towers and poles with the help of insulator. and poles with the help of insulator. Thus the insulators play an Thus the insulators play an important role in the successful important role in the successful operation of the lines. Principally operation of the lines. Principally the insulator are made of porcelain the insulator are made of porcelain and stealite the later had the and stealite the later had the advantage of very much higher advantage of very much higher tensile & bending strength tensile & bending strength compared with porcelain tightened compared with porcelain tightened glass in another material which is glass in another material which is some time is used for insulators.some time is used for insulators.

Types of insulators:Types of insulators: 1.1. PIN INSULATOR PIN INSULATOR

2.2. SUSPENSION INSULATORSUSPENSION INSULATOR

T clamp

Violated hardware

Suspension insulator

Pin insulator

BUCHHOLZ RELAYBUCHHOLZ RELAY 1.1. Gas operated relay Gas operated relay

(buchholz relay):(buchholz relay): it is a gas it is a gas actuated relay used for actuated relay used for protective oil immersed protective oil immersed transformer against all transformer against all types of fault. It indicates types of fault. It indicates presence of gases in case of presence of gases in case of some minor fault and take some minor fault and take out the transformer out of out the transformer out of the circuit in case of serious the circuit in case of serious fault. It is connected fault. It is connected between the main tank and between the main tank and conservator tank through conservator tank through pipe. It is full of oil under pipe. It is full of oil under normal condition of normal condition of operation. It consists of cast operation. It consists of cast housing containing a hinged housing containing a hinged hollow float, inside of which hollow float, inside of which is a mercury switch.is a mercury switch.

PROTECTIVE RELAY PROTECTIVE RELAY Protective relaying is necessary with almost every electrical plant . The choice of Protective relaying is necessary with almost every electrical plant . The choice of

protection depends upon several aspects such as typed and rating of the protection depends upon several aspects such as typed and rating of the protected equipment, its importance, location probable abnormal condition, protected equipment, its importance, location probable abnormal condition, cost etc. the protective relays sense the abnormal condition in a part of a cost etc. the protective relays sense the abnormal condition in a part of a power system and gives an a alarm or isolates that part from healthy power system and gives an a alarm or isolates that part from healthy system. The relays distinguish between normal and abnormal condition. system. The relays distinguish between normal and abnormal condition. Whenever an abnormal condition develops, the relays close its contacts. Whenever an abnormal condition develops, the relays close its contacts. Thereby trip circuit of the circuit breaker is closed. Current from the Thereby trip circuit of the circuit breaker is closed. Current from the battery supply flows in the trip coil of the circuit breaker and the circuit battery supply flows in the trip coil of the circuit breaker and the circuit breaker open and the fault part is disconnected from the supply.breaker open and the fault part is disconnected from the supply.

THE FUNCTION OF PROTECTIVE RELEYTHE FUNCTION OF PROTECTIVE RELEY::1.1. To sound & alarm or to close the trip ckt or ckt breaker so as to disconnect To sound & alarm or to close the trip ckt or ckt breaker so as to disconnect

a component, which include overload, under frequency, short ckt etc. a component, which include overload, under frequency, short ckt etc. 2.2. To disconnect the abnormally operating path so as to prevent the To disconnect the abnormally operating path so as to prevent the

subsequent faults.subsequent faults.3.3. To disconnect the faulty part quickly so as to minimize the damage to faulty To disconnect the faulty part quickly so as to minimize the damage to faulty

part. part. 4.4. To localize the effect of fault by disconnecting the faulty part from healthy To localize the effect of fault by disconnecting the faulty part from healthy

part causing least disturbance to the healthy system.part causing least disturbance to the healthy system.5.5. System to disconnect the faulty part quickly so as to improve the system System to disconnect the faulty part quickly so as to improve the system

stability, service continuity and performance.stability, service continuity and performance.

Classification of relaysClassification of relays the relays consists of one or more elements which are the relays consists of one or more elements which are

actuated by the electrical quantities of the circuit in which actuated by the electrical quantities of the circuit in which they are connected the relay can also be classified they are connected the relay can also be classified according to their operating characteristics as detailed according to their operating characteristics as detailed below :-below :-

1. SOLENOID TYPE 2. ATTRACTED TYPE 3. 1. SOLENOID TYPE 2. ATTRACTED TYPE 3. ELECTRO DYNAMIC TYPE ELECTRO DYNAMIC TYPE

4. MOVING COIL TYPE 5. IDUCTION TYPE 6. 4. MOVING COIL TYPE 5. IDUCTION TYPE 6. THERMAL RELAY THERMAL RELAY

7. DIRECTIONAL OR REVERSE CURRENT TYPE 7. DIRECTIONAL OR REVERSE CURRENT TYPE 8. DIRECTIONAL OR REVERSE POWER TYPE 9. 8. DIRECTIONAL OR REVERSE POWER TYPE 9.

DEFFERENTIAL RELAYSDEFFERENTIAL RELAYS10. UNDER VOLTAGE, UNDER CURRENT AND UNDER 10. UNDER VOLTAGE, UNDER CURRENT AND UNDER

POWER RELAYSPOWER RELAYS11. OVER VOLTAGE, OVER CURRENT AND OVER POWER 11. OVER VOLTAGE, OVER CURRENT AND OVER POWER

RELAYS RELAYS 12. DISTANCE RELAYS 12. DISTANCE RELAYS

LightningLightning arrestor arrestor• It must provide a conducting It must provide a conducting

path to the earth as and when path to the earth as and when abnormal transient voltage abnormal transient voltage occurs on the system.occurs on the system.

• It must be capable to carry the It must be capable to carry the discharge current safely without discharge current safely without getting it self damaged under getting it self damaged under transient voltage condition.transient voltage condition.

• The power frequency current, The power frequency current, following the breakdown, must following the breakdown, must be interrupted as soon as the be interrupted as soon as the transient voltage has fallen transient voltage has fallen below the breakdown value. below the breakdown value.

• It should not pass any current to It should not pass any current to earth in the normal working earth in the normal working voltage of the system. In other voltage of the system. In other words, it should acts as insulator words, it should acts as insulator at normal working voltage. at normal working voltage.

TOWERSTOWERSTowers are useful for long transmission Towers are useful for long transmission

uses. Generally broad base lattice uses. Generally broad base lattice steel towers are used. Which are steel towers are used. Which are mechanically strong and have long mechanically strong and have long life basically steel towers are two life basically steel towers are two types :types :

1.1. Narrow base lattice type towerNarrow base lattice type tower2.2. Broad base lattice type towerBroad base lattice type towerNarrow base lattice type tower are Narrow base lattice type tower are

used for 11kV or 33kV. Where as used for 11kV or 33kV. Where as broad towers are used for 66kV & broad towers are used for 66kV & above. above.

Types of tower:Types of tower:1.1. A typeA type= suspension= suspension2.2. B typeB type = cut point = cut point 3.3. C typeC type = heavy towers. In this = heavy towers. In this

tower, moving angle is 30tower, moving angle is 3000-45-4500

4.4. D typeD type = heavy towers. It is used = heavy towers. It is used to move the line at an angle to the to move the line at an angle to the give supply at different place. In give supply at different place. In this tower, we can move the line this tower, we can move the line at 90at 9000 . .

IsolatorsIsolators • Isolators operates on no load Isolators operates on no load

condition.condition.• It does not have any It does not have any

specified current breaking specified current breaking capacity.capacity.

• Its disconnect to one section Its disconnect to one section of an electrical device from of an electrical device from its other line section, thus its other line section, thus providing a visible break.providing a visible break.

• While opening a circuit, a While opening a circuit, a circuit breaker is opened circuit breaker is opened first and then isolator is first and then isolator is operated to open the circuit. operated to open the circuit. And reverse process to And reverse process to closing the circuit.closing the circuit.

• Isolators used in power Isolators used in power system are generally 3poles system are generally 3poles and one poles isolators.and one poles isolators.

• In three poles isolators In three poles isolators middle isolators is moving middle isolators is moving and connected rode is and connected rode is mechanically moved. mechanically moved.

CIRCUIT CIRCUIT BREAKERSBREAKERS• The circuit breakers is just like a switch which can be The circuit breakers is just like a switch which can be

operated manually or automatically. operated manually or automatically. • It’s operated in normal or fault condition.It’s operated in normal or fault condition.• when CB connectors is make and break arc is when CB connectors is make and break arc is

generate but the medium in the CB like oil, SF6, generate but the medium in the CB like oil, SF6, vacuum or air blast arc is quenched.vacuum or air blast arc is quenched.

All high voltage CB may classified into four typesAll high voltage CB may classified into four types1.1. oil circuit breaker oil circuit breaker 2.2. Air blast circuit breakerAir blast circuit breaker3.3. VaccumVaccum4.4. SFSF66

OIL CIRCUIT BREAKEROIL CIRCUIT BREAKER1.1. Oil CBOil CB: In the oil CB CB’s are : In the oil CB CB’s are

filled with transformer oil to filled with transformer oil to extinguish the arc during extinguish the arc during opening of the contacts and opening of the contacts and also to insulated the current also to insulated the current conducting parts from one conducting parts from one another and from the earthed another and from the earthed tank. tank.

Advantage: Advantage: i.i. The arc energy is decomposed The arc energy is decomposed

in oil.in oil.ii.ii. The good cooling properties of The good cooling properties of

the oil.the oil.iii.iii. The oil serves as a good The oil serves as a good

insulating medium.insulating medium.

Disadvantage:Disadvantage:i.i. It is easily inflammableIt is easily inflammableii.ii. It may form an explosive It may form an explosive

mixture with air .mixture with air .iii.iii. It require maintenanceIt require maintenance

Oil

le

vel

ind

icat

or

On/off indication

AIR BLAST CIRCUIT AIR BLAST CIRCUIT BREAKERBREAKERAir blast CBAir blast CB: : the ABCB the ABCB

effectively are used in effectively are used in system operating at system operating at 132kV and above up to 132kV and above up to 400kV with breaking 400kV with breaking capacities 7000MVA and capacities 7000MVA and above. These breakers above. These breakers employ compressed air employ compressed air (18-20 kg/cm(18-20 kg/cm22) for arc ) for arc extinction. The ABCB extinction. The ABCB has the following has the following advantage;advantage;

Chances of fire hazard Chances of fire hazard are almost eliminated.are almost eliminated.

The operation speed is The operation speed is very high. very high.

The maintenance of The maintenance of ABCB is much less. ABCB is much less.

Reclosure at high speed Reclosure at high speed is possibleis possible

Air

ta

nk

VACUUM CIRCUIT VACUUM CIRCUIT BREAKERBREAKER

Vacuum CBVacuum CB: : the vacuum the vacuum CB works on principle CB works on principle that vacuumthat vacuum is used to is used to serve the purpose of serve the purpose of insulation and it implies insulation and it implies that pressure of gas at that pressure of gas at which break down which break down voltage becomes voltage becomes independent of pressure. independent of pressure. Vacuum is superior Vacuum is superior dielectric medium and it dielectric medium and it is better than all other is better than all other media except air and media except air and sulphur which are sulphur which are generally used at high generally used at high pressure.pressure.

SFSF6 6 CIRCUIT BREAKERCIRCUIT BREAKER• The SF6 circuit breaker of CG2 The SF6 circuit breaker of CG2

manufactured in collaboration with manufactured in collaboration with are of single pressure “PUFFER are of single pressure “PUFFER TYPE”. They represent the latest TYPE”. They represent the latest circuit breaker design technology.circuit breaker design technology.

• The breaker generates the The breaker generates the quenching medium pressure quenching medium pressure during the breaking process.during the breaking process.

• The pressure of the SF6 gas in the The pressure of the SF6 gas in the breaker is low, there by breaker is low, there by eliminating the need for extra eliminating the need for extra heating of the SF6 gas heating of the SF6 gas compartment.compartment.

• In the new SF6 circuit breaker In the new SF6 circuit breaker have an extra compressed air tank have an extra compressed air tank for make and break the contact.for make and break the contact.

CURRENT CURRENT TRANSFORMERTRANSFORMER•Current is measured by current xmer.

•The In the CT primary winding is connected in series with line carrying the current to be measured.

•Primary wdg consists of very few turns and, due to this, there is no appreciable voltage drop across it. The secondary Wdg of C.T. has large number of turns and the exact number of turns can be determined by the turns ratio.

• The ammeter or wattmeter current coil are connected directly across the secondary Wdg terminals, therefore, a current transformer operates its secondary nearly under short ckt condition.

•One of the terminals of the secondary Wdg is earthed so as to protect equipment and personnel in case of insulation breakdown in

the current xmer

POTENTIAL POTENTIAL TRANSFORMERTRANSFORMER• The primary winding of P.T. is The primary winding of P.T. is

connect across the line connect across the line carrying the voltage to be carrying the voltage to be measured measured

• voltage circuit is connected voltage circuit is connected across the secondary winding.across the secondary winding.

• The loading of P.T. is always The loading of P.T. is always small (sometimes only few volt-small (sometimes only few volt-amperes)amperes)

• Design of P.T. is quit similar to Design of P.T. is quit similar to that of a power transformer. that of a power transformer.

• secondary wdg consists very secondary wdg consists very few turns and load connected few turns and load connected in the secondary.in the secondary.

• P.T have a large core and P.T have a large core and conductor size than power conductor size than power transformer.transformer.

• P.T. size is large but current is P.T. size is large but current is less so losses is not less so losses is not appreciableappreciable..

P.L.C.C.P.L.C.C.

Power line carrier communication Power line carrier communication system differs in the method of system differs in the method of calling, the power supply or in the calling, the power supply or in the modulation system. Each end of the modulation system. Each end of the power line is provided with identical power line is provided with identical carrier equipment consisting of carrier equipment consisting of transmitter, receiver, line tunning transmitter, receiver, line tunning unit master oscillator, power amplifier unit master oscillator, power amplifier etc. Brief illustration of P.L.C.C. etc. Brief illustration of P.L.C.C. system given in this section.system given in this section.

Power Line carrier Communication

WAVE TRAPWAVE TRAP• Wave trap is used in the G.S.S. to Wave trap is used in the G.S.S. to

G.S.S. communication. G.S.S. communication. • It have inductive coil which It have inductive coil which

provides high impendence for the provides high impendence for the higher frequency.higher frequency.

• These high impendence provide by These high impendence provide by tunning system. tunning system.

• Cause of higher impedances its coil Cause of higher impedances its coil block the communication signal.block the communication signal.

• In this construction have a lightning In this construction have a lightning arrester which protect the coil from arrester which protect the coil from the high faulty voltage and current. the high faulty voltage and current.

• It is connected in the series with It is connected in the series with the supply line busbar.the supply line busbar.

• Its one end is connected to the Its one end is connected to the C.V.T. C.V.T.

C.V.T.C.V.T.• The C.V.T. consists of a capacitive The C.V.T. consists of a capacitive

potential divider and an inductive medium potential divider and an inductive medium voltage circuit.voltage circuit.

• The inductive part is immersed in mineral The inductive part is immersed in mineral oil and sealed with an air cushion a steel oil and sealed with an air cushion a steel tank ;one, two or three capacitor units are tank ;one, two or three capacitor units are mounted on the tank and are used as mounted on the tank and are used as capacitive potential divider .capacitive potential divider .

• Capacitor is used for communication Capacitor is used for communication frequency filtrations and it is behave like a frequency filtrations and it is behave like a short circuit for hair frequency.short circuit for hair frequency.

• Capacitance of the Coupling capacitor is Capacitance of the Coupling capacitor is 400 400 μμF.F.

• Potential transformer is used for metering, Potential transformer is used for metering, protection of yard equipments etc. protection of yard equipments etc.

• It have star point. It have star point.

ON LOAD TAP CHANGERON LOAD TAP CHANGER• The on-load tap changer consists of the diverted switch The on-load tap changer consists of the diverted switch

installed into a pressure tight oil compartment separated installed into a pressure tight oil compartment separated from xmer oil & the tap selector mounted below it. The tap from xmer oil & the tap selector mounted below it. The tap changer is attached to the xmer cover by means of tap changer is attached to the xmer cover by means of tap chager head, which also serves for coupling the drive shaft chager head, which also serves for coupling the drive shaft and for connecting a pipe to the oil conservator. If required, and for connecting a pipe to the oil conservator. If required, the tap selector may be equipped with a change over the tap selector may be equipped with a change over selector. selector.

CAPACITOR BANKCAPACITOR BANK• Capacitor bank is used Capacitor bank is used

for improve the power for improve the power factor of the feeder side. factor of the feeder side.

• It also improve the It also improve the voltage .voltage .

• R.V.T. is a residual R.V.T. is a residual voltage transformer. voltage transformer.

• Series reactor is a Series reactor is a device who controlled device who controlled the high value current the high value current and maintain the need and maintain the need current. current.

R.V.T. CAPACITOR Series reactor

EARTHINGEARTHING Earthing of non current parts from the point of view of safety of personnel. Earthing of non current parts from the point of view of safety of personnel.

Earthing of generator and Xmer neutral to provide for an operative protected Earthing of generator and Xmer neutral to provide for an operative protected system.system.

The common Earthing bus is employed to which are connected the frames of all The common Earthing bus is employed to which are connected the frames of all electrical machines. The causes of instrument Xmer, switch board, Earthing electrical machines. The causes of instrument Xmer, switch board, Earthing line, insulator base, building structure etc . Thus if the Earthing system is line, insulator base, building structure etc . Thus if the Earthing system is effective, a zero or nearly zero earthing potential will be established on all effective, a zero or nearly zero earthing potential will be established on all metal parts which may otherwise develop a dangerous potential with respect metal parts which may otherwise develop a dangerous potential with respect to earth in case of an earth fault. to earth in case of an earth fault.

The earth resistance magnitude is approximately 0.1 The earth resistance magnitude is approximately 0.1 ΩΩ. .

NEED OF EARTHINGNEED OF EARTHING • To sufficient low impedance path to fault current to facilitate satisfactory To sufficient low impedance path to fault current to facilitate satisfactory

operation equipment under fault condition. operation equipment under fault condition. • To ensure that living (steady state) being in the vicinity of sub station are not To ensure that living (steady state) being in the vicinity of sub station are not

exposed to unsafe potential under steady state and during fault condition. exposed to unsafe potential under steady state and during fault condition. • To retain system voltage within reasonable limit under fault condition (such To retain system voltage within reasonable limit under fault condition (such

as lighting, switching surge or inadvertent contact with higher voltage as lighting, switching surge or inadvertent contact with higher voltage system) and ensure that voltage is not exceeded upto insulation break down system) and ensure that voltage is not exceeded upto insulation break down level. level.

• Graded insulation can be used in power Xmer in solidly earthed system. Graded insulation can be used in power Xmer in solidly earthed system. • A means of monitoring the insulation of the power equipment. A means of monitoring the insulation of the power equipment.

EARTHING EARTHING TRANSFORMERTRANSFORMER

• Earthing transformer is Earthing transformer is used for the earthing of used for the earthing of neutral point or wire of neutral point or wire of the delta connected the delta connected winding. Because in delta winding. Because in delta have no neutral point so have no neutral point so it is provide neutral point it is provide neutral point of the delta connected of the delta connected winding. winding.

BATTERY ROOM BATTERY ROOM D.C. systemD.C. system

1.1. (+) Plate :- it consists of lead boroxide PbO(+) Plate :- it consists of lead boroxide PbO2 2 deposits on the grid frame. deposits on the grid frame.

2.2. (-)Plate :- it consists of porous sponge of lead deposits on a grid frame an (-)Plate :- it consists of porous sponge of lead deposits on a grid frame an antimony lead allow similar to that (+) plate.antimony lead allow similar to that (+) plate.

3.3. Separator :- its function to keep the +ve & -ve plate electrically part. It Separator :- its function to keep the +ve & -ve plate electrically part. It consists of a thin sheet of canon conducting porous material.consists of a thin sheet of canon conducting porous material.

4.4. Container :- it is made of hard rubber it is a box in which assembly is kept.Container :- it is made of hard rubber it is a box in which assembly is kept.

5.5. Electrolyte :- it is dilute HElectrolyte :- it is dilute H22SOSO44 acid containing 31% acid by weight by acid containing 31% acid by weight by weight & 21% by volume. The specific gravity of electrolyte is 1.23 at 27weight & 21% by volume. The specific gravity of electrolyte is 1.23 at 27o o cc

6.6. Connector :-the function of connector is to connect two battery in series in a Connector :-the function of connector is to connect two battery in series in a battery tank, it is made of thick CU strips specific gravity condition of battery tank, it is made of thick CU strips specific gravity condition of Battery Battery

1.22 to 1.23 100% charged 1.22 to 1.23 100% charged

1.2 to 1.21 75% charged1.2 to 1.21 75% charged

1.75 to 1.85 60% charged1.75 to 1.85 60% charged

1.15to 1.16 25% charged 1.15to 1.16 25% charged

BATTERY CHARGINGBATTERY CHARGING :- discharged battery burg charged by a battery charger. :- discharged battery burg charged by a battery charger. There are two battery charger one for 110V battery & other for 220V There are two battery charger one for 110V battery & other for 220V battery. The different methods are available for charging of battery such as;battery. The different methods are available for charging of battery such as;

1.1. Tricle charging 2. Float charging 3.boost charging Tricle charging 2. Float charging 3.boost charging

4. Constant voltage charging 5. constant current charging 4. Constant voltage charging 5. constant current charging

FIR PROTECTION FIR PROTECTION SYSTEM SYSTEM

In order to guard against possibility of a In order to guard against possibility of a sudden pressure caused by break down sudden pressure caused by break down

on a short circuiton a short circuit in transformer in transformer winding. When the oil is convert in the winding. When the oil is convert in the gas form the level of the oil is down and gas form the level of the oil is down and mercury switch contact is connect and mercury switch contact is connect and the relay is operate and a motor is going the relay is operate and a motor is going on start and nitrogen kit valve is open so on start and nitrogen kit valve is open so all the oil is relief in 5second like 5000 all the oil is relief in 5second like 5000 liters. And nitrogen gas is struck the arc liters. And nitrogen gas is struck the arc or an quenching medium. or an quenching medium.

CONTROL ROOM CONTROL ROOM Control room is used to control to working the battery room, compressor Control room is used to control to working the battery room, compressor

room and electrical instrument and protecting devices present in the room and electrical instrument and protecting devices present in the yard of G.S.S. the equipment used for this purpose are compact and yard of G.S.S. the equipment used for this purpose are compact and they are provided for:-they are provided for:-

1.1. Control and inducting equipment.Control and inducting equipment.

2.2. Relay and indication equipment voltage regulation.Relay and indication equipment voltage regulation.

At 220kv G.S.S. cubical construction of panel board are used. Mash cubical At 220kv G.S.S. cubical construction of panel board are used. Mash cubical are arranged in a line side by side.are arranged in a line side by side.

Different panels of different circuit breaker, transformer, lightning Different panels of different circuit breaker, transformer, lightning arrester, isolator, current transformer and potential transformer, arrester, isolator, current transformer and potential transformer, P.L.C.C. etc. are coming to the control room. In each set of panel there P.L.C.C. etc. are coming to the control room. In each set of panel there are at least over current and one earth fault relay. From control panel are at least over current and one earth fault relay. From control panel the operate can know what is happening in the sub station yard. The the operate can know what is happening in the sub station yard. The operator can control, start, regulate or switch off the main circuit from operator can control, start, regulate or switch off the main circuit from control panel. In sub station the control and relaying equipment is control panel. In sub station the control and relaying equipment is installed in control room. The diagram of main connection are given in installed in control room. The diagram of main connection are given in front face of the panel there diagram indicate the position of the C.B. front face of the panel there diagram indicate the position of the C.B. and isolator. The control operate get the idea as to which can be and isolator. The control operate get the idea as to which can be increased to accommodate relay and other equipment in case complex increased to accommodate relay and other equipment in case complex protective scheme relay panel is necessary.protective scheme relay panel is necessary.

SAFETY PRECAUTION SAFETY PRECAUTION 1.1. Always wear uniform & shoes. They are for your safety. Always wear uniform & shoes. They are for your safety. 2.2. Ring and watches can get caught in the machinery. Do not wear them when on Ring and watches can get caught in the machinery. Do not wear them when on

duty.duty.3.3. Be alert and mind on your job, don’t see dream. Be alert and mind on your job, don’t see dream. 4.4. Do not be over confident if may lead to a major accident.Do not be over confident if may lead to a major accident.5.5. Playing and monk eying is dangerous, avoid it.Playing and monk eying is dangerous, avoid it.6.6. Be watch full of blind corner you may be caught in wrong way.Be watch full of blind corner you may be caught in wrong way.7.7. Do not smoke in prohibited area.Do not smoke in prohibited area.8.8. Keep the work area clean, dry, chip fee and free of obstruction.Keep the work area clean, dry, chip fee and free of obstruction.9.9. Do not touch/ operate equipment unless you are authorized mind sharp edges.Do not touch/ operate equipment unless you are authorized mind sharp edges.10.10. Lubricate the M/C part with bore hands use cloth cotton waste brush etc. as Lubricate the M/C part with bore hands use cloth cotton waste brush etc. as

required.required.11.11. Do not repair or try to adjust any equipment.Do not repair or try to adjust any equipment.12.12. Ensure all guard are in position before M/C working on job.Ensure all guard are in position before M/C working on job.13.13. Ensure all M/C control of the M/C are accessible to you.Ensure all M/C control of the M/C are accessible to you.14.14. Do not attempt to change the speed of M/C in running. Do not attempt to change the speed of M/C in running. 15.15. Use the right tool for the job in right way.Use the right tool for the job in right way.16.16. Don’t use over size spanner using wood or skin on packing piece.Don’t use over size spanner using wood or skin on packing piece.17.17. Don’t use broken, damaged or warm out tools, nuts etc. for damping.Don’t use broken, damaged or warm out tools, nuts etc. for damping.18.18. Keep yourself at a safe distance from the cutting tools action.Keep yourself at a safe distance from the cutting tools action.19.19. Don’t touch measures job when it is hot or in motion.Don’t touch measures job when it is hot or in motion.20.20. For any injury whether small or big get first aid first.For any injury whether small or big get first aid first.