Project Report of Electrical

8/3/2019 Project Report of Electrical

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IN ELECTRICAL SYSTEM

(15 JUNE TO 20 JULY) NUCLEAR POWER CORPORATION

(A GOVT. OF INDIA ENTERPRISE)

GUIDED BY: PREPARED BY :Mr. RAMESH CHANDRA REKHA VERMATraning Suptd. B.E IIInd Year (ELECTRICAL)

A.M.U, ALIGARHMr.S.K.Verma, SO/E

Traning officer

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1) I am indebted & thankful to our respectable ShriN.S. RANA, SO/F, Electrical Engineer forextending all his advices, help and guidancehereby making it possible for me to complete

the project.

2) I am also thankful to S/Shri H.S.SINGH,AJAYPATHAK,& R.K. SHARMA for his help, supportand cooperation.

REKHA VERMAB.E. IIIrd YearELECTRICAL

A.M.U, ALIGARH

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Energy : The pulse of all life

And the lord said Let there be light.

This verse from the holy bible clearly brings out the dependence of the light, but it also

further our scientific belief that energy is most definitely the key component in the foundationas well as flourishing of all life on this planet. Just the perfect amount of solar energy

reaching earth has enabled life to evolve here.

Today the human beings, we find ourselves resting on the pinnacle of progress, but if we trace

the history of our civilization, we will find that through the ages, we have measured our

development eventually in terms of how much energy we can produce, consume, convert or

govern. In his long journey from a measly slave to the master of nature, man has learned to

harness energy and to use it for his own benefit.

One careful look around us shall be sufficient to reveal that today, we live our lives in the

cozy cradle of a world which is moulded to suit best to our requirements by the advancedtechnology of the day; and technology, it just provides us with never and better ways to

manipulate energy and put it to use. Our lamps convert electrical energy to light to illuminate

our world, our cars burn petrol to give mechanical energy and enhance our locomotion and

our air-conditioners working as reverse heat engines, cool our room to suit our need.

We can very reasonably say that energy in some form or the other, is the pulse of our lives

today. After all can we imagine our lives without the machines and the gadgets buzzing

around us but what is worth noting here is that we always need to supply any appliances with

energy and manipulate it for our benefit. If we want to run our car, we need to supply it with

the chemical energy in the form of petrol, if we want our fans; we need to supply it with

electrical energy. One of the fundamental laws of nature is the law of conservation of energy.

We need to provide energy to our entire energy based appliances before they can be of any

use

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INTRODUCTION OF NAPS

One of the chief aims of the Department Of Atomic Energy is the

development of Nuclear Energy for economic generation as analternative source of electric power when in due course the conventionalsources will be exhausted in the country.

Petroleum prices are escalating. The amount of coal required for 400MWe power generations of the order of 5 x 10 6 kgs per day. Whereas anuclear power station of the same capacity need only 200 kg of AtomicFuel per day. Transportation of coal of such magnitude over longdistance is not economical.

The strategy adopted for Indian Nuclear Power program is that heavywater power reactors using natural uranium would produce power andplutonium in the first stage. The plutonium produced from these reactorswould be used to set high breeding ratio fast reactors to produceadditional power and plutonium in the second stage. In the third stagethorium would be utilized in both the fast and the thermal reactors whichwould give unlimited source of power.

Consequently it was decided to build twin PHWR (pressurized Heavywater reactor) type of power reactors. The site is selected by a highpowered committee, based on the need of electrical power, the potentialof industrial expansion, availability of large quantities of water and lesspopulation.

NARORA, a small ancient village, is situated on the bank of holy riverGanga in the district Bulandshahr in Uttar Pradesh. The plant is about 60km from Aligarh which is the nearest population centre.

With the synchronization of the Narora Atomic Power Station withnorthern grid through five lines of 220KV, it occupied an important placeon the power map of the India. With this, yet another important milestonein the Indian nuclear programme has been achieved as NAPS is an efforttowards standardization of PHWR units and a stepping stone to the500MWe units. A significant and unique feature of this project has beenthe evolution of the design suitable for seismic sites.

The NAPS is a twin unit module of 220MWe each of pressurized heavy

water reactors. The reactors use natural uranium available in India asfuel and heavy water produced in the country as moderator and coolant.

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The execution of this project, including design, engineering erection,commissioning, and operation has been done by the Indian engineersand Scientists. The foreign exchange component is about only 10% of

the project cost of Rs. 723 crores- mostly for the import of specialmaterials and equipment.

NAPS is the fourth Nuclear Power Station in the country after Tarapur inMaharasthra, Rawatbhata in Rajasthan & Kalpakkam in TamilNadu.NAPS is the 1st indigenous nuclear power plant of India. The station hastwo pressurized heavy water reactors with an installed capacity of 220Mwe each using natural uranium as fuel.

The station is connected to high voltage net work through five 220 KVlines, one to Moradabad, one to Harduaganj, one to Simboli, and two tokhurja. It is designed for base load operation as a commercial station.

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NARORA ATOMIC POWER STATION

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Reactor building houses the reactor primary heat transport system,moderator system, reactivity system, fuel handling system and some ofthe auxiliaries. The turbo-generator and its associated conventionalequipment, emergency diesel sets, control and power MG sets, stationbatteries, electrical switch gear compressors, chillers and main controlroom are located in turbine building. Both the units share common

facilities such as service building, spent fuel storage bay and otherauxiliary devices such as heavy water upgrading and wastemanagement facility.

NAPS has two natural draught cooling and two induced draughtcooling towers.

NAPS has the following main parts:-

1. Administration Building.2. Overhead water tank.3. Canteen4. Natural Draught Cooling Towers5. 220KV Switch Yard6. Stack.7. Service Building8. Small LOCA Room.9. Reactor Building.

10. Purification Building11. Turbine Building12. Pump house

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S.NO DATA SPECIFICATION

1. Transmission Lines Five

230KV Narora-Moradabad Single Line

230KV Narora-Harduaganj Single Line

230KV Narora-Shimboli Single Line

230KV Narora-Khurja Double Line

2. Stack Height 142 Meters

3. NDCT Height 128 Meters

4. NDCT Top Dia. 107 Meters

5. NDCT Base Dia. 58 Meters

6. NDCT Throat Dia. 53 Meters

7. Steam Flow 1314 Tonnes/hour

8. PHT Flow 12700 Tonnes/hour

9. Steam Pressure 48-40 kg/cm2

10. PHT Pressure 87.0 kg/cm2

11. CCW Flow 39000 Tonnes/hour

12. Coolant Tubes 306

13. No. of Fuel Bundles in one channel 12

14. Fuel Bundle Weight 15 kgs

15. Condenser Pressure 680 mm of hg

16. RB Design Pressure 1.25 kg/cm2

17. Station Load 18-20 MWe

18. Generator Power 220 MWe19. Grid Voltage 220 KV

Foundation Stone 4th

Jan. 1974 4th

Jan. 1974Excavation Started 15th Feb. 1976 15th Feb. 1976

Fuel loading 11th oct. 1988 9th aug. 1991

Ist criticality 12th march 1989 24th oct. 1991

Commercialization 29th July 1989 5th Jan. 1992

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Following are the Indias atomic power stations operating as on today:-

S.NO. PLACE CAPACITY

1. TAPS (1 & 2) 2X160MWe

2. RAPS (1 & 2) 2X220MWe

3. MAPS ( 1 & 2) 4. NAPS( 1 & 2)

5. KAKRAPAR ( 1 & 2)

6. KAIGA ( 1 & 2)

7. RAPS ( 3 & 4)

8. TAPS ( 4) 1X540 MWe

Following are the power stations under construction:-

S.NO. PLACE CAPACITY

1. TAPS ( 3 ) 1X540 MWe

2. RAPS ( 5 & 6 ) 2X220 MWe

3. KAIGA ( 3 & 4 ) 2X220 MWe

4. KUNDAKULAM ( 1& 2 ) 2X1000 MWe

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Nuclear Power Plants generate electricity. A Thermal Power Plant burns

coal to produce heat. The heat converts water to steam, which in turndrives the turbine and the generator to produce electricity. The maindifference between the Nuclear Power Plant and the Thermal PowerPlant is that Thermal Power Plant gets heat energy by burning coalwhereas the Nuclear Power Plant produces heat by the process calledFission of U-235 Nuclei. The heat produced is used to convert water intosteam. The steam runs the turbine and generator and the electricity isgenerated by the generator.

The fission energy is transported from the fuel bundle with the help ofhigh-pressure heavy water called Primary Heat Transport (PHT). ThePHT System takes away the heat from the fuel bundles and exchangesthis heat to the Demineralised water (Feed water) into the steamgenerator and the steam at a pressure of 40-48 Kg/cm2 is generated inthe steam generator. This steam is then transported through pipes toturbine hall where the turbine and the generator are installed. This steamis then admitted to the turbine, which runs at a speed of 3000 rpm. Thegenerator also runs at the same speed as both are coupled together with

the coupling. The generator rotor is excited here with the DC voltage andEMF is produced at the stator of generator at 16.5 KV. This generatedvoltage is then stepped up from 16.5 KV to 230 KV by a three phasetransformer and this stepped up electricity is then sent to the stationswitchyard for the further transmission to the Northern Grid. This steamafter working in the turbine is condensed into a surface type ofcondenser and the condensed steam are again fed back to the steamgenerator through a chain of six reheaters.

NUCLEAR REACTION

In a fission reaction, besides the two fission products, a few (in the caseof U-235 2.47 on the average) neutrons are emitted . The principle ofchain reaction is very easy therefore: a U235 nucleus is hit by a neutron,upon which fission occurs at a high probability. The neutrons produced inthis process can cause more fissions, 200 MeV energy is released eachtime. Consequently, the process becomes self-sustaining and noexternal neutron source is needed any longer.

If the neutrons produced from a fission induce only one new fission(because of escaping from the system or being captured inside) we say

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that the chain reaction is of constant intensity. If the neutrons generatedfrom a fission reaction induce more than one fission than more and morefission reactions will take place in a unit time and the chain reaction willbe diverging.

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PROTECTIVE RELAY

It is a device, which senses the abnormal condition ofelectrical equipment or system and isolation. The faultparty from the system by tripping the appropriate circuitbreakers.

Some abnormal conditions are: -

1. Insulation failure.2. Breakage of conductor.3. Localized heating.4. Inadequate Rating.

EFFECT OF FAULT:

Damage to equipment due to excessive current.

Loss of supply to large parts of the system.

FUNCTIONAL CHARACTERSTICS OF RELAY

Selectivity

Protection is arranged in zones, which should cover thepower system completely leaving no part unprotected.

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Sensitivity

It refers to the smallest value of actuating quantity atwhich protection start operating in relation with theminimum value of fault current in protected zone.

Stability

It refers to the ability of the system to remain to all load

condition and faults external to relevant zone.

Speed

The function of automatic protection is to isolate faultfrom the power system in much shorter time to meet thefollowing.

Reliability

The protection should not fail to operate in the event offaults in the protected zone.

TYPES OF RELAY:

Some important relays are given below: -

Instantaneous over current Relay:

It is applied for phase fault protection of Motor feeders,Transformers feeders etc.

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Earth fault relay type:

It is basically an over current relay used for earth faultprotection of motor feeders and transformer feeder. Itprovides time delayed over current protection.

Definite time over current relay:

The relay is used for time grade over current protectionfor feeders and stalling protection for motors.

Under voltage relay:

If under voltage occurs below the set point of relay,itdrops and DC relays picks up to give trip signal forbreaker.

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Instantaneous differential relay

It is basically a 3 phase over current relaydesigned for more sensitive application. The waythe relay will be connected in the ckt gives it thename differential. The relay is past action andsensitive. It is used for short ckt protection for bigmotor generators.

Fuse failure relay

It is used for detecting the failure or inadvertentremoval of voltage transformer, secondary fusesand prevention of incorrect tripping of ckt breakereg:- failure of pt secondary fuse in distance

protection can result in tripping of the feeder.

Directional Inverse time over current relay

Relays will operate for current flowing in eitherdirection. Directional over current relays operate

only in one particular direction of power flow asdesired.

Transformer differential Relay

It is used in phase to phase fault and ground faultprotection of power T/F.

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It runs at the speed of 3000 RPM. The generator is also runs at thesame speed as both are coupled together with the coupling. Thegenerator rotor is excited here with DC voltage and EMF is producedat

Capacity - 260MVA

Voltage on H.v. - 235Kv

L.V. - 16.5 Kv

Vector Group - YD11

Tap changer - off load.

Cooling - OFWF% impedance - 14 %

H.V. Bushing - 245Kv, 800A outdoor oil immersed self contained

bushings are provided for H.V. side.

H.V. Neutral Bushing - 1000 A , 36Kv weather proof cover mountedshaded porcelain bushing is provided for H.v. neutral.

L.V. Bushing - 7500 A, 24 Kv weather proof cover mounted shaded

porcelain bushing are provided for L.V. bushing.

The neutral end of H.V. winding is brought out through a 36 Kv porcelainbushing provided with C.T. and solidly earth.

Two explosion vents are mounted on the T/F tank

provided with rupture diaphgram. These diaphgram

rupture and relieve the excess pressure that built up

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inside transformer during serious internal fault and thus

protects the transformer tank from deformities.

The transformer is specified with a voltage rate pf220/6.9 KV. The HV voltage corresponds to the voltageof the HV buses of the main output system. The L.V.voltage of 6.9 KV is the no load voltage of the LV side

on load the voltage drop in the SUT will reduce theterminal voltage to 6.6 KV with the proper selection oftap.

The star/star connection for HV/LV winding werechosen in order to obtain proper vector matching of 6.6KV unit and station system. The SUT is also specified

with a unloaded tertiary. The tertiary has a power ratingof about 1/3 of the main winding. The choice ofpercentage impedance for the transformer depends onthe fault level obtainable on the L.V. side and the voltagedrop under full load conditions and motor startingconditions percentage impedance of 0.9% specifiedlimits. The LV fault level to 500 MVA and the voltage

drops to permissible level.

The transformer is specified with an unload tap changer

to maintain steady voltage at the 6.6 KV bus. The onload tap changer has range of +/- 12% insteps of 1-5%. Here only two nos. SUT available for initial start upto unit and supply power to station auxiliary when unit is

in shut down. SUT take supply from 220 KV grid & Feed

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to station auxiliary power rating of SUT specified -22/31.5 MVA.Normal load of SUT specified - 20.8 MVA

Including D2O upgrading plant of 7 MVA T/FLoad on SUT when unit transfer is not availableincluding D2O upgrading plant load 7 MVA - 34.8 MVAType of transformer - outdoor, 3 phase core typeRated voltage - 220/6.6 KVWinding connection Yd1Y0Frequency - 50 Hz

Winding impedance % (HV-LV) 9%.Winding temperature rise plot to exceed 50 C over 50C ambient.

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INTRODUCTION

The class-I power supply consist of two main buses.BUS-U and BUS-V each is fed from 500 Kw. ACVR isfed from class-III buses BUS-P and BUS-Q respectively.Each bus has a 2200 AH battery bank connected to it.The normal supply is fed from class-III buses fromACVR and battery bank is floating on DC bus. The lossof class-III power supply battery bank is supplied2200AH or two 30 min. with the end of discharge voltage204V.

PURPOSE OF BATTERIES:

In NAPS batteries bank play a very important rolebecause these batteries are used at the time when theclass supply system-IV, III and II fails. Due to this,batteries start the important loads of a NAPS.

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ACVR

BATTERY

BANK 250 V

DCMOTOR ACGENERATOR IMPORTANTLOADS

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NUMBER OF BATTERIES BANK CAPACITY:

Capacity of BB No. of Bank.

250 V DC power BB 2200 AH 2 per unit.250 V DC control BB 450 AH 2 per unit.48 V DC control BB 300 AH 3 per unit.

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SYSTEM DISCRIPTION:

The D.G. set are capable for the parallel

operation of the class IV and other D.G. set. Wheneverclass four supplies are lost the D.G. set automaticallystart within 30 sec. the system is grounded through aresistance 0.5 ohm. To limit the ground fault current to480 amp. Or less.

Rated continuous output - 1450 kwOverload capacity for 8 hrs. - 1650 kwOverload capacity for 2 hrs. - 1750 kw

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OPERATIONAL REQUIREMENTS& CONSTRUCTIONAL FEATURES

DIESEL ENGINE

The diesel engine is started by air motor. We store theair in air receiver by the compressor and this air gives sixstarts to D.G. set. For cooling we use oil and heavywater. The cooling arrangement form closed path andcool by the jacket water. If the engine is not in operation

we use pre-lubricating oil pump for diesel engine whichcirculate the oil in engine after 30 min. We use boosterto give more fuel to engine to start it. We control thespeed of the governing system.

TECHNICAL DATA OF DIESEL ENGINE

1.Rating :2600 BHP2.RPM :1000rpm3.No.of strokes :4 stoke4. power factor :0.8 lag5. Engine cylinder :16 cylinder6. Excitation : static Exitation

7. Pole : 6 pole8. Excitation voltage : 58.5 V9. Excitation current : 326 A

10. Connection : star, 3 phase

In the generator we use lap wound type of statorwinding. We excite the generator by 48 V D.C. voltage

through the slip ring to the rotor or field winding. And by

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the rotation of rotor an e.m.f. is produced in the statorwinding. If the generatorgenerates 60% of the voltagethen to excite the field winding we use generated

voltage.

POWER MOTOR GENERATOR SET:

This topic covers the control, protection andannunciation of motor generator set.

SYSTEM DESCRIPTION:

The motor generator set described are meant foruninterrupted power supply (415v ,3 phase ,50 Hz ) toimportant auxiliaries. The d.c. motor of this MG set fromclass-1st 250v dc supply and 500kw ACVR from class 3rd

supply and 2200 AH 250V DC batteries.

On loss of class 4th supply, the class 3rd system willalso loose supply. DG set start restore class 3rdsupply.During this period the 250V DC batteries will continue tosupply the MG set.

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STARTING METHOD:

In view of the large size (290 kW) of the DC motor of the

MG set starting with pony motor has preferred to resistorcontrolled starting on class 1st bus.

SYSTEM GROUDING:

In order to reduce the ground fault in the machine isgrounded through a neutral grounding resistor of 0.4

ohm. This will restrict ground fault current to 600A orless.

PARALLEL OPERATION

The MG set can be parallel to the DG set for the purposeof shut down.

PROTECTION

The following protections are provided for theDG motor.

D.C. MOTOR PROTECTION

1. Over speed protection2. Over voltage protection3. Under frequency and over frequency protection4. Main field under current protection5. Motor over load protection

ALTERNATOR PROTECTION:25


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1. Phase instantaneous over current protection2. Backup phase over current protection

3. Over current protection4. Earth fault protection

PONY MOTOR PROTECTION:

Over load protection

Thermister sensed excess temp. protection.

TECHNICAL DATA:

AC MACHINE

Rated terminal voltage :425V

Rated continuous output at 0.8 pf :325KVAOver load rating for 30 min :360KVAInsulation class : FLocked rotor current on the :1250Abase load of 140Kw

DC MOTOR

Rated normal terminal voltage :258VMaximum working terminal voltage :300VMinimum working terminal voltage :200V

Rating :290 KWNo load armature current :60A

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Full load speed :1000rpmArmature current at rated voltage :1350 AInsulation class :F

PONY MOTOR

Rating : 37 Kw , 1000 rpmRated voltage : 415V , 50HzCurrent : 67 V

TECHO GENRATOR

Output : 150V at 1000rpm

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The major parameters of the switchyard are givenbelow :

1. Type :outdoor2. Nominal Voltage :220KV3. Max. operating voltage :240 KV4. Basic impulse levels:

(a) For transformer winding : 950 KV(peak)(b) For other equipment : 1050

5. 3 phase fault level :10000 MVA

6. Short time current rating : 23.6 KA/secfor all equipment

7. Minimum creep age distance :5600mm totaland For insulation and bushing 2800mmpollute

8. Number of strain /Suspension/ 6 nos.

insulation /string : 254 X 140 fog type9. Specified current rating for -(a) Main bus bar : 2000A(b) Bus coupler bay bus : 2000A(c) Bay bus of other element :750A

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(1) THE CIRCUIT BREAKER : -

There are 11 Nos. of C.B used in switchyard.These C.B are air blast type manufactured by M/s

Hindustan Brown Bravery. Following C.B are usedin switchyard as per follows

CB No. USEDCB -1 Bus couplerCB -2 Generated transformer - (Unit#1)

CB -3 Start up transformer - (Unit#1)CB -4 One line MuradabadCB -5 SUT - (Unit#2)CB -6 One line - ShimbholiCB -7 One line - KhurjaCB -8 One line - Khurja

CB -9 GT - (Unit#2)CB -10 Transfer BusCB -11 One line - Harduaganj

There is a centralized compressed air systemfor feeding air to the circuit. The compressors arehoused in the compressor room located on theeastern side of the switchyard. The air piping is

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made of copper tubes and are run inside cabletrenches in the switchyard. A ring main systemwith two feed points and in the piping to facilitates

isolation of any breaker circuit without disturbingair connection to the other circuits.

These CB are normally closed at pressureabout 30 kg/cm2.

(2) ISOLATORS / DISCONNECTING SWITCH:

There are 44 Isolators used in switchyard. TheIsolators are Pneumatically Operated type and arecapable of remote control from control room.These Isolators are worked only on off timecondition. The Isolators are of M/s TMG make and

are supplied by M/s Volts. Air supply for pneumaticcontrol of the Isolators is also available from thesame centralized compressor mentioned in ParaC.s.I. through separate reducers to reduces thepressure to the required Operating levels forIsolators.

Grouping Switch are provided on the lineIsolators. These grounding switches aremechanically interlocked with the main Isolators.

(3) LIGHTNING ARRESTORS

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Lighting arrestors are provided on all five lines attheir entry into switchyard and also near the HV

terminals of the power transformer. The arrestorsare of heavy-duty station type manufactured byM/s WS Insulators. The main parameters of thearrestor are as below-

Rating - 198 KV

Discharge current - 10 KAImpulse spark over voltage - 550 KV peakSwitching surge spark over - 420/453 KV Powerfrequency spark over - 1.5 times rated

VoltageReset Voltage - 205 KV

VOLTAGE TRANSFORMER

In line with the UPSEBs Practice of providingCVTs for feeding distance protection of lines,CVTs are provided on all 3Q of the 220 KV lines.These CVTs serve the dual function via. VT for the

line protection and coupling capacitor for carriercommunication.

Each main bus bar is provided with one set ofelectromagnetic VT for the purpose of meteringsynchronizing and feeding other protection circuit.One single phase cut is provided for the transferbus for synchronizing purposes.

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CURRENT TRANSFORMER

Current transformers are used for measure thelarge current flowing in a power line of an ACsupply. It is connected in series with phase wires.Current transfer is connected in switchyard tomeasure the current. It has very few turns (evenmay be one turn only ) on primary winding and

large number of turns in the secondary winding. Its permeability, low retentively low power loss.Current transformer is oil immersed or compoundfield. Lastly, we can check the large current flowingin a power line of any AC supply system time totime.

CARRIER COMMUNICATION

Carrier communication facilities are provided forcommunication between NAPS control room andGrids substations connected to NAPS. Phasecoupling has been envisaged for single circuit lines

and inter circuit has been envisaged for doublecircuit line to Khurja wave traps are provided onphases associated with the communication.

The carrier Communication Channel is alsoused for transmitting signals for line protection.

SYNCHRONIZING ARRANGEMENT ANDREMOTE CONTROL

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The remote controls for the switchyard circuit areprovided on the control room of NAPS.

Synchronizing facilities are available forsynchronizing any element to the line bus bars.Emergency and synchronizing control from controlroom.

All isolators can also be controlled remotely

from the central control room. However thegrounding switches have to be operated manuallyat the switchyard.

In NAPS turbo generator is cylindrical poletype, which is directly couple to the turbine andmounted on the same, TG SHORT The turbogenerator has an output rating on 264MVA

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(237.5MW) at 0.9PF , 16.5KV, 3000 rpm with stemcondition of 39.71Kg/cm2 (9) pressure and 0.26%wet and 250.3C at inlet to stop valve. After

expansion in a single flow high-pressure turbinemoisture is extracted. In Separator -cum-reheatedwhere steam is reheated to 233 C before it entersthe double flow low-pressure turbine. Stem isextracted from suitable stage of the turbine toprovide for six stages representative feed

heating ,with a final feed water, temperature of169.05 C. The local quantity of stem flow to theturbine is around 1333.58 tones/hour and designrate of heat turbo generator is 2758 K cal/kWh.

Stator, conductor is water-cooled. Thestarter bore and Rotor are cooled by Hydrogen,

since excitation current requirement is large with amaximum of 5000 rpm. Inductor type highfrequency exciter is chosen to avoid commutationproblem, which are experienced in DC exciter.

PRINCIPLE:The electric generator is based on the principal offaraday laws of electromagnetic Inductiondiscovered by Michael Faraday in 1831.

E= -NdQ/dt

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N = No. of turns

DQ/dt = Rate of change of flux

E = Induced EMF

ESSENTIAL REQUIREMENT FOR ONDUCED INA GENERATOR : -

1. A conductor, where the voltage is induced.

2. Magnetic field.3. Relative motion between conductor andmagnetic field.

FOR EXICTATION OF GENERATOR:

we use static excitation for 235mw, because of

following reason : - Fast response time.

High reliability.

Interchangeability of part during operation.

Very low maintenance.

Less space requirement.

THE STATIC EXICTATION SYSTEM CONSISTOF THE FOLLING :

1. Excitation transformer.2. Controlled Rectifier Bridge.3. Automatic Voltage regulator.

4. Field breaker.5. Field flashing circuit.

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1.Excitation transformer :

Three single phase dry type transformer rated for833 kv, 16.5kv/332 voltage are connect in delta tothe 16.5 kv system though tap of bus duct from themain generator bus duct. The Lv side of thetransformer are connected in the star and feed therectifiers the DC output of which is fed to the field

winding of the generator.

2.Controlled rectifier bridge :

There are in all four controlled, three-phasethyristar rectifier bridges feeding the field. Thebridges are fed from the excitation transformer and

are parallel on the output side. Three bridge areadequate the requirement of the excitation andfourth bridge is stand-by to take care of theeventually of one bridge failure. The control signalfor the thyristar are received the regulator cubicles(AVR).

3.Automatic voltage regulator :Control signals are generated here for rectifier.The AVR derives its input form the PT and CT ofthe generator and controls the excitation forvarying the machine terminal voltage and reactiveoverflow in addition to this basic function of AVR in

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voltage regulator. The AVR incorporates thefollowing addition feature.

(a) Rotor current limit :

AVR protect rotor from overloading and theexcitation system from suffering voltage in excessof the ceiling voltage, the transformer theyre bytime delay features.

(b) Under excitation limit :A load angle limits in the scheme limits the

minimum excitation to a valve to which the AVRcan run down and prevents the machine formfailing out of step due to under excitation.

(c) Slip stabilization :

This is provided to monitor rotor oscillation andaddition single drive from these oscillation areapplies to the AVR to prevent the machine formfailing out of step.

(d) Stator current limiter :-

This limiter monitors the stator current limits theexcitation in case there is stator over load.

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4. Field breaker :

The field breaker is of air breast type. In this

breaker provision is provided to discharge theenergy stored in the field though a non-linearresistance whenever the breaker is open themeans of a special contact of the breaker whenclasses before the field breaker opens.

5. Field flushing circuit :

While starting the machine it will be necessary toprovide supply to the field from an external source(415v) three phase transformer rectifier which havefield discharge resistor and over voltage-protection, rotor earth fault relay because the

terminal connected transformer will not haveadequate voltage to supply the field. The flushingcircuits built the generator voltage to above 70 %of the rated voltage where in the AVR takes overthe built and maintains the voltage at the set valve.

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MAIN PART OF THE GENERATOR:STATOR :

Stator care is made of segment varnish insulatedof cold rolled grain oriented silicon steel assemblewith care bars for cooling of care by hydrogen (3.5kg/cm2) steel spacer are provided.

Stator binding is a 3 phase double layer shortcarded bar type binding having two parallel paths.Fiber wages are provided to hold up coil. Slatesare semi closed.

ROTAR:

Rooter is of cylindrical pole type the shaft and bodybeing forced from one piece of an alloy ofchromium, nickel, molybdenum and vanadiumsteel the rotor binding is held in position againstcentrifugal forces by Duralumin wages in the stateportion and by non magnetic steel retaining rings.

Damper binding is provided in the rotor toprevent over heating of retaining rings during nonsynchronous operation. This damper binding alsoavoid hunting due to unbalanced loading and faultcondition.

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SLIP RINGS :-

Slips rings made of steel, along with brush gear is

provided in the TG shaft to eject excitation currentfrom the static rectifier unit to the rotating mainfield. The slip rings consists of halically group ofimproving brush performance on the rotor shaftand insulated form it the slip rings are providedwith inclined holes for self ventilation.

COOLING OF GENERATOR :

Stator cooling :

Generator stator binding are cooled by DM waterpassing through the hollow conductor. The ring

type water made of copper are provided separatelyfor DM water inlet and outlet in the stator on theturbine ends.

DM water is used for stator binding coolingpurpose because of it have : -

Low viscosity No fire hazards

Better heat removal capacity

Low conductivity

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Rotor cooling :

Stator and rotor is cooled by hydrogen in the statorand rotor air gap. To axial shaft fans mounted onboth end of rotor body to circulated hydrogen gasin to independent and semitrically closed circuit.

The direct cooling of rotor binding is done by

the gap pick up method. Multi-jet flow of hydrogenexposes large amount of rotor binding copper tothe cooling medium thus creating very effectivecooling.

For indigenously gas cooler are mounted in thestator body for hydrogen cooling. Hydrogen gas is

used for generator because of it have.

Heat conductivity is high

Density is very less

Heat removed capacity is high

As to have low voltage losses.

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TECHNICAL DATA OF TURBO GENERATOR

1. Power - 237700 KW2. Power factor - 0.903. Rating - 264000 KVA4. Stator - 16500 V ,9240 A5. Rotor - 326 , 27556. RPM - 3000 RPM

7. Frequency - 50 Hz8. Connection - 3 phase9. Coolant - DM water & Hydrogen10. Insulation - b-type11. Production - 1991-9212. Made by - Haridwar

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CLASSIFICATION OF SUPPLY SYSTEM INNAPS

CLASSES OF POWER SUPPLY:

Each load within the station has been classifiedaccording to degree of reliability required for itssupply.There are four classes of power supply at NAPS.

Class ofPower Voltage Nature Source

Class-I 250 VDC Uninterrupted Batterybank

Class-II 415 AC Uninterrupted Power MGset

Class-III 415 AC interruptible

two minutes

Diesel

generatoronly for oneor rotor.

Class-IV 415 AC &6.6 KV

interruptibleupto 30minutes

Grid supply& TG Set

Control

powersupplyCl-I

250 VDC uninterrupted Batteries.

ControlpowersupplyCl-II

415 VAC240 VAC48 VDC28 VDC

Uninterruptedsets.

Control MGsets

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Class-IV POWER SUPPLY:

The system has in CWPH. BU-J acts as transfer bus.

Each bus is charged through an 6.6 KV/415V auxiliarytransfer from 6.6 KV buses. BU-J is kept charged buthas no load and acts as S/by Bus for BU-K, BU-M ofclass-IV in case of unavailability of any auxiliary X-mer.

BU-J also acts as standby Bus for BU-P & BU-Q of

class-III system .

RWPH, NAPP Township, upgrading plant and someMCC's are fed from Class IV in addition to 415 V loadson Class IV. When the grid fails & our plant trips, then6.6 KV and 415 V class IV both systems are dead.Loads on these buses interrupt and do not cause

any adverse effect on Reactor auxiliaries.

CLASS-III POWER SUPPLY :

System feeds to those loads which can beinterrupted shortly. These loads are required to run

even when Reactor is shut down .

System is normally charged from 6.6 KV system andwhen the 6.6 KV supply fails DGs automatically startand recharge the system.

415 V class III has two main buses BU-P and BU-Q.Both are fed by 6.6 KV system through x-mers. Two44


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auxithe source of supply is from class-III through

transformer and rectifier. Class-III inturn is fedfrom grid. Class III resumes after 1-2 min.after class IV failure.

But when class III does not resume the source of poweris from 250 V DC storage batteries and the supplyremains uninterrupted. Batteries have capacity tosupply upto 25 min. when class III is not available.

CLASS-II POWER SUPPLY :

Class-II BU-S & BU-T are kept constantly charged bytwo power generator sets to convert 250 V DC to 415V AC. As the motor of MG set is driven by 250 VDCfrom class-I power batteries, the class-II is also

uninterrupted power supply.

Class-II may also be tied to class-III if any MG setbecomes unavailable. This condition calls continuousDG set running.

Potential loss on any cl-III or any cl-II buses initiateemergency transfer i.e. all DG's start to charge anydead bus.

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CLASS-I POWER SUPPLY :

250 VDC control power supply sources are two 250VDC battery banks. Each bank supplies to one bus.Normally the buses are kept charged from class-IIIpower through automatic constt. voltage rectifiers(ACVR). On class-III failure batteries supply therequired power. Batteries are recharged on class-IIIresumption.

Control power supply is used for auto trippingckt., auto closing ckt. & test ckt. for breakers remotely(CR) and locally testing. This has been separated fromclass-I power supply system keeping in view all time,availability and reliability

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PLANT LAYOUT

Reactor building houses the reactor primary heat

transport system, moderator system, reactivitymechanism, fuel handling system and some of theauxiliaries. The turbo-generator and its associatedconventional equipment, emergency diesel sets, controland power MG sets, station batteries, electrical switchgear compressor, chillers and main control room arelocated in turbine building. Both the units share common

facilities such as service building, spent fuel storage bayand other auxiliary services such as heavy waterupgrading and waste management facility.

NAPP has two natural draught cooling and two induceddraught cooling towers.

Legend

1. Administration Building.2. Overhead Water Tank.3. Canteen4. Natural Draught Cooling Towers5. 220 KV Switch Yard.6. Stack

7. Service Building8. Small LOCA Room9. Reactor Building10. Purification Building11. Turbine Building.12. Pump House13. Induced Draught Cooling Towers.

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.

S.NO. CONTENTS

1. INTRODUCTION.

2. RELAY TESTING LAB.3. GENERATOR TRANSFORMER.4. STARTUP TRANSFORMER.5. STATION BATTERIES.6. DIESEL GENERATOR SET.7. SWITCH YARD.8. TURBO GENERATOR.

9. CLASSIFICATION OF SUPPLY INNAPS.

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Project Report of Electrical

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Transcript of Project Report of Electrical