summer training report ntpc

7/28/2019 Summer training report ntpc

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SUMMER TRAINING

REPORT

2012

NTPC LIMITED

BADARPUR THERMAL

POWER STATION


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Training at BTPS

I was appointed to do 6 week training at this esteemedorganization from 11th June to 21st July, 2012. I was assigned to visitvarious division of the plant, which were:

Electrical Maintenance Department I (EMD-I) Electrical Maintenance Department II (EMD-II) Control and Instrumentation Department (C&I)

These 6 weeks training was a very educational adventure for me. Itwas really amazing to see the plant by yourself and learn howelectricity, which is one of our daily requirements of life, isproduced. This report has been made by my experience at BTPS.The material in this report has been gathered from my textbook,senior student reports and trainers manuals and power journalsprovided by training department. The specification and principlesare as learned by me from the employees of each division of BTPS.

Anubhav Ghosh


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INDEX

1) ABOUT NTPC2) STRATEGIES

3) JOURNEY OF NTPC

4) ABOUT BTPS

5) OPERATION OF POWER PLANT6) PARTS OF A POWER PLANT

7) VARIOUS CYCLES AT POWER STATION

8) ELECTRICAL MAINTENANCE DEPARTMENT-

9) ELECTRICAL MAINETNANCE DEPARTMENT-II

10) CONTROL AND INSTRUMENTATION


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ABOUT NTPC Indias largest power company, NTPC was set up

in 1975 to accelerate power development inIndia.

NTPC became a Maharatna company in May,2010, one of the only four companies to beawarded this status.

The total installed capacity of the company is39,174 MW (including JVs) with 16 coal based and7 gas based stations, located across the country.

In addition under JVs, 7 stations are coal based &another station uses naptha/LNG as fuel.

The company has set a target to have an installedpower generating capacity of 1,28,000 MW bythe year 2032.


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Strategies of NTPC


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JOURNEY OF NTPC


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About BTPS BADARPUR THERMAL POWER STATION was established on 1973 and it was the

part of Central Government. On 01/04/1978 is was given to NTPC. Since then operating performance of NTPC has been considerably above

the national average. Badarpur thermal power station started with a single 95 mw unit. There were 2 more units (95 MW each) installed in next 2 consecutive years. Now it has total five units with total capacity of 720 MW. Ownership of BTPS

was transferred to NTPC with effect from 01.06.2006 The power is supplied to a 220 KV network that is a part of the northern grid. The ten circuits through which the power is evacuated from the plant are:

1. Mehrauli2. Okhla3. Ballabgarh4. Indraprastha

5. UP (Noida)6. Jaipur


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Given below are the details of unit with the year

theyre installed


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OPERATION OF A POWER PLANT

Basic Principle As per FARADAYs Law-Whenever the amount of magnetic flux linked

with a circuit changes, an EMF is produced in the circuit. Generator workson the principle of producing electricity. To change the flux in thegenerator turbine is moved in a great speed with steam.

To produce steam, water is heated in the boilers by burning the coal. In a Badarpur Thermal Power Station, steam is produced and used to spin

a turbine that operates a generator. Water is heated, turns into steam and spins a steam turbine which drives

an electrical generator. After it passes through the turbine, the steam is condensed in

a condenser. The electricity generated at the plant is sent to consumers through high-

voltage power lines The Badarpur Thermal Power Plant has Steam Turbine-Driven Generators

which has a collective capacity of 705MW.

The fuel being used is Coal which is supplied from the Jharia Coal Field inJharkhand.

Water supply is given from the Agra Canal.


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Basic Steps of Electricity Generation

The basic steps in the generation of electricity

from coal involves following steps:

Coal to steam

Steam to mechanical power

Mechanical power to electrical power


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PARTS OF A POWER PLANT1. Cooling tower2. Cooling water pump3. Transmission line (3-phase)4. Unit transformer (3-phase)5. Electric generator (3-phase)6. Low pressure turbine7. Condensate extraction pump8. Condenser9. Intermediate pressure turbine10. Steam governor valve11. High pressure turbine

12. Deaerator13. Feed heater14. Coal conveyor15. Coal hopper16. Pulverised fuel mill17. Boiler drum18. Ash hopper19. Super heater20. Forced draught fan

21. Reheater22. Air intake23. Economiser24. Air preheater25. Precipitator26. Induced draught fan27. Flue Gas


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VARIOUS CYCLES AT POWER STATION

PRIMARY AIR CYCLE

SECONDARY AIR CYCLE

COAL CYLCE

ELECTRICITY CYCLE

FLUE GAS CYCLE

CONDENSATE CYCLE

FEED WATER CYCLE

STEAM CYCLE


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ELECTRICAL MAINTENANCE DEPARTMENTI(EMD-I)

It includes:

Motors High Tension/Low Tension Switchgear

Coal handling plant


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MOTORSAC MOTORS

Squirrel cage motor

Wound motor

Slip ring induction motor

In modern thermal power plant three phase squirrel cage induction motors are used but sometimedouble wound motor is used when we need high starting torque e.g. in ball mill.

THREE PHASE INDUCTION MOTOR

Ns (speed) =120f/p Stator can handle concentrated single layer winding, with each coil occupying one stator slot

The most common type of winding are:

DISTRIBUTED WINDING :This type of winding is distributed over a number of slots.

DOUBLE LAYER WINDING :Each stator slot contains sides of two different coils.

SQUIRREL CAGE INDUCTION MOTOR

Squirrel cage and wound cage have same mode of operation. Rotor conductors cut the rotatingstator magnetic field. an emf is induced across the rotor winding, current flows, a rotor magnetic fieldis produced which interacts with the stator field causing a turning motion. The rotor does not rotateat synchronous speed, its speed varies with applied load. The slip speed being just enough to enablesufficient induced rotor current to produce the power dissipated by the motor load and motor losses.


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BEARINGS AND LUBRICATIONS

A good bearing is needed for trouble free operation of motor. Since it is very costly part

of the motor, due care has to be taken by checking it at regular intervals. So lubricatingplays an important role. Two types of lubricating are widely used Oil lubrication

Grease lubrication

Insulation

INSULATION

Winding is an essential part so it should be insulated. Following types of insulation arewidely used

INSTRUMENTS SEEN

MICROMETER

This instrument is used for measuring inside as well as outside diameter of bearing.

MEGGAR

This instrument is used for measuring insulation resistance.

VIBRATION TESTER

It measures the vibration of the motor. It is measured in three dimensions-axial, verticaland horizontal.


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SWITCH GEAR

Switchgear is one that makes or breaks the electrical circuit.

It is a switching device that opens & closes a circuit that defined as apparatus usedfor switching, Lon rolling & protecting the electrical circuit & equipments.

The switchgear equipment is essentially concerned with switching & interruptingcurrents either under normal or abnormal operating conditions.

The tubular switch with ordinary fuse is simplest form of switchgear & is used to control& protect& other equipments in homes, offices etc.

For circuits of higher ratings, a High Rupturing Capacity (H.R.C) fuse in condition witha switch may serve the purpose of controlling & protecting the circuit.

However such switchgear cannot be used profitably on high voltage system (3.3 KV)

for 2 reasons. Firstly, when a fuse blows, it takes some time to replace it & consequently there is

interruption of service to customer.

Secondly, the fuse cannot successfully interrupt large currents that result from the HighVoltage System.

In order to interrupt heavy fault currents, automatic circuit breakers are used.

There are very few types of circuit breakers in B.P.T.S they are VCB, OCB, and SF6 gascircuit breaker.

The most expensive circuit breaker is the SF6 type due to gas.

There are various companies which manufacture these circuit breakers: VOLTAS,

JYOTI, and KIRLOSKAR. Switchgear includes switches, fuses, circuit breakers, relays & other equipments.

In low tension switch gear thermal over load relays are used whereas in high tension 5different types of relays are used.


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THE EQUIPMENTS THAT NORMALLY FALL IN THISCATEGORY ARE:-

ISOLATOR

Isolator cannot operate unless breaker is open Bus 1 and bus 2 isolators cannot be closed simultaneously

The interlock can be bypass in the event of closing of bus coupler breaker.

No isolator can operate when the corresponding earth switch is on

SWITCHING ISOLATOR Switching isolator is capable of:

Interrupting charging current Interrupting transformer magnetizing current Load transformer switching. Its main application is in connection with the transformer feeder as the unit

makes it possible to switch gear one transformer while the other is still on load.

CIRCUIT BREAKER One which can make or break the circuit on load and even on faults is referred to as circuit

breakers. This equipment is the most important and is heavy duty equipment mainly utilized forprotection of various circuits and operations on load. Normally circuit breakers installed areaccompanied by isolators.

LOAD BREAK SWITCHES These are those interrupting devices which can make or break circuits. These are normally on same

circuit, which are backed by circuit breakers

EARTH SWITCHES Devices which are used normally to earth a particular system, to avoid any accident happening

due to induction on account of live adjoining circuits. These equipments do not handle anyappreciable current at all. Apart from this equipment there are a number of relays etc. which areused in switchgear.


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Low Tension SWITCHGEAR

MAIN SWITCH

Main switch is control equipment which controls or disconnects the main supply. The mainswitch for 3 phase supply is available for the range 32A, 63A, 100A, 200Q, 300A at 500Vgrade.

FUSES

With Avery high generating capacity of the modern power stations extremely heavycarnets would flow in the fault and the fuse clearing the fault would be required towithstand extremely heavy stress in process. It is used for supplying power to auxiliaries withbackup fuse protection. With fuses, quick break, quick make and double break switch fusesfor 63A and 100A, switch fuses for 200A,400A, 600A, 800A and 1000A are used.

CONTACTORS

AC Contractors are 3 poles suitable for D.O.L Starting of motors and protecting theconnected motors.

OVERLOAD RELAY

For overload protection, thermal overload relay are best suited for this purpose. Theyoperate due to the action of heat generated by passage of current through relayelement.

AIR CIRCUIT BREAKERS

It is seen that use of oil in circuit breaker may cause a fire. So in all circuits breakers at largecapacity air at high pressure is used which is maximum at the time of quick tripping ofcontacts. This reduces the possibility of sparking. The pressure may vary from 50-60kg/cm^2for high and medium capacity circuit breakers.


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Contactors used in ntpc

Thermal overload relay


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HT SWITCHGEAR

MINIMUM OIL CIRCUIT BREAKER

These use oil as quenching medium.

AIR CIRCUIT BREAKER In this the compressed air pressure around 15 kg per cm^2 is used for

extinction of arc caused by flow of air around the moving circuit . Thebreaker is closed by applying pressure at lower opening and opened byapplying pressure at upper opening. When contacts operate, the cold airrushes around the movable contacts and blown the arc

SF6 CIRCUIT BREAKER The principle of current interruption is similar to that of air blast

circuit breaker. It simply employs the arc extinguishing medium namelySF6. When it is broken down under an electrical stress, it will quicklyreconstitute itself.

VACUUM CIRCUIT BREAKER It works on the principle that vacuum is used to save the purpose of

insulation and. In regards of insulation and strength, vacuum issuperior dielectric medium and is better that all other medium except airand sulphur which are generally used at high pressure.


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OIL CIRCUIT

BREAKERS

AIR CIRCUIT

BREAKERS

SF6 CIRCUIT

BREAKERS


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COAL HANDLING PLANT (CHP)

The coal handling plant consists of two plants: Old Coal Handling Plant (OCHP)

New Coal Handling Plant (NCHP)

The OCHP supplies coal to Unit- I, II, III &NCHP supplies coal to Unit- IV and V.

COAL SUPPLIED AT BTPS

Coal is supplied to BTPS by Jharia coal mines.


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COAL CYCLE


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The main constituents of CHP plant are:-

WAGON TIPPLERWagon from coal yard come to the tippler and emptied here. There are 2 wagon tipplers in

the OCHP. CONVEYER

Conveyer belts are used in the OCHP to transfer coal from one place to other as required ina convenient & safe way.

ZERO SPEED SWITCHIt is used as a safety device for the motor i.e. if the belt is not moving & the motor is ON,then it burns to save the motor. This switch checks the speed of the belt & switches off themotor when speed is zero.

METAL DETECTORAs the conveyer belt take coal from wagon to crusher house, no metal piece should goalong with coal. To achieve this objective, metal detectors & separators are used.

CRUSHER HOUSEBoth the plants i.e. OCHP & NCHP use TATA crusher powered by BHEL motor. Crusher isdesigned to crush the pieces to 20 mm size i.e. practically considered as the optimum sizefor transfer via conveyer.

ROTARY BREAKERIf any large piece of metal of any hard substances like metal impurities comes in theconveyer belt which cause load on the metal separator, then the rotary breaker rejectsthem reducing the load on the metal detector.

PULL GUARD SWITCH

These are the switches which are installed at every 10m gap in a conveyer belt toensure the safety of motors running the conveyer belts. If at any time some accidenthappens or coal jumps from belt and starts collecting at a place, then the switchcan be used.


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SEQUENTIAL OPERATION OF OCHP

Unloading the coal

Crushing & storage.

Conveying to boiler bunkers.

Coal arrives to plant via road, rail, sea, and river or canal route fromcollieries. Most of it arrives by rail route only in railway wagons. Coalrequirement by this plant is approximately 10,500 metric ton/day.

This coal is tippled into hoppers. If the coal is oversized (400 mm sq),then it is broken manually so that it passes the hopper mesh wherethrough elliptic feeder it is put into vibrators & then to conveyor belt 1A &1B.

The coal through conveyor belts 1A & 1B goes to the crusher house. Alsothe extra coal is sent to stockyard through these belts.

In the crusher house the small size coal pieces goes directly to the belt 2A& 2B whereas the big size coal pieces are crushed in the crusher & thengiven to the belts 2A & 2B.

The crushed coal is taken to the bunker house via the conveyor belts 3A& 3B where it can be used for further operations.


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OCHP


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SEQUENTIAL OPERATION OF NCHP

Coal arrives in wagons and tipples into hoppers. if the coal is oversized (400mm sq), then it is broken manually sothat it passes through the hopper mesh.

From hopper it is taken to TP-6 12A & 12B.

Conveyors 12A & 12B take the coal to the breaker house whichrenders the coal size to be 100 mm sq.

Metal separator & metal detector are installed in conveyor belts14A/B & 15A/B respectively to remove the metal impurities

Stones which are not able to pass through the 100mm sq mesh ofhammer are rejected via 18A & 18B to the rejection house.

Extra coal is sent to the reclaim hopper via conveyor 16A & 16B.

From TP-7, coal is taken by conveyor 14A & 14B to the crusherhouse whose function is to render size of the coal to 20mm sq.


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NCHP


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ELECTRICAL MAINTENANCE DEPARTMENTII

(EMD-II)

It includes:

Generators Transformers

Switch yard


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GENERATORS

The generator works on the principle ofelectromagnetic induction. There are twocomponents stator and rotor. The rotor isthe moving part and the stator is the stationarypart. The rotor, which has a field winding, isgiven a excitation through a set of 3000rpm togive the required frequency of HZ. The rotor iscooled by Hydrogen gas, which is locallymanufactured by the plant and has high heatcarrying capacity of low density. If oxygen and

hydrogen get mixed then they will form veryhigh explosive and to prevent their combining inany way there is seal oil system. The statorcooling is done by de-mineralized (DM) waterthrough hollow conductors. Water is fed by oneend by Teflon tube. A boiler and a turbine arecoupled to electric generators. Steam from theboiler is fed to the turbine through theconnecting pipe. Steam drives the turbine rotor.The turbine rotor drives the generator rotorwhich turns the electromagnet within the coilof wire conductors.

Carbon dioxide is provided from the top and oilis provided from bottom to the generator. Withthe help of carbon dioxide the oil is drained outto the oil tank.


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RATINGS OF THE GENERATORS USED

Turbo generator 100MW

TURBO GENERATOR 210 MW

The 100 MW generator generates 10.75 KV and210 MW generates 15.75 KV. The voltage is

stepped up to 220 KV with the help of generatortransformer and is connected to the grid.

The voltage is stepped down to 6.6 KV with thehelp of UNIT AUXILLARY TRANSFORMER (UAT) andthis voltage is used to drive the HT motors. Thevoltage is further stepped down to 415 V and then

to 220 V and this voltage is used to drive Lt Motors.


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TURBO GENERATOR 100MW

MAKE BHEL, Haridwar

CAPACITY 117,500 KVA

POWER 100,000 KW

STATOR VOLTAGE 10,500 VSTATOR CURRENT 6475 A

SPEED 5000rpmPOWER FACTOR 0.85

FREQUENCY 50 HZ

EXCITATION 280 V


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TURBO GENERATOR 210MW

MAKE BHEL, HaridwarCAPACITY 247,000 KVA

POWER 210,000 KWSTATOR VOLTAGE 15,750 VSTATOR CURRENT 9050 ASPEED 5000 rpmPOWER FACTOR 0.85FREQUENCY 50 HZ

EXCITATION 310 VGAS PRESSURE 3.5 kg/cm


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TRANSFORMERS

It is a static machine which increases ordecreases the AC voltage without changingthe frequency of the supply.

It is a device that: Transfer electric power from one circuit

to another. It accomplishes this by electromagnetic

induction. In this the two electric circuits are in mutual

inductive influence of each other.

WORKING PRINCIPLE:It works on FARADAYS LAW

OF ELECTROMAGNETIC INDUCTION (selfor mutual induction depending on the type oftransformer).


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COOLING OF TRANSFORMERS

OF LARGE MVA

As size of transformer becomes large, the rate of the oil circulating becomes insufficient todissipate all the heat produced & artificial means of increasing the circulation by electricpumps. In very large transformers, special coolers with water circulation may have to beemployed.

TYPES OF COOLING:

Air cooling

Air Natural (AN)Air Forced (AF)

Oil immersed cooling

Oil Natural Air Natural (ONAN)

Oil Natural Air Forced (ONAF)

Oil Forced Air Natural (OFAN)

Oil Forced Air Forced (OFAF)

Oil immersed Water cooling

Oil Natural Water Forced (ONWF)

Oil Forced Water Forced (OFWF)


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MAIN PARTS OF TRANSFORMER1. Secondary Winding2. Primary Winding.3. Oil Level4. Conservator

5. Breather6. Drain Cock7. Cooling Tubes.8. Transformer Oil.9. Earth Point10. Explosion Vent11. Temperature Gauge.12. Buchholz Relay13. Secondary Terminal14. Primary Terminal


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GENERATOR TRANSFORMER

(125MVA UNIT-I & UNIT-III)

RATING 125MVA

TYPE OF COOLING OFB

TEMP OF OIL 45^C

TEMP WINDING 60^C

KV (no load) HV-233 KVA

LV-10.5 KVA

LINE AMPERES HV-310 A

LV-6880

PHASE THREE FREQUENCY 50 HZ

IMPEDANCE VOLTAGE 15%

VECTOR GROUP Y DELTA

INSULATION LEVEL HV-900 KV

LV-Neutral-38

CORE AND WINDING WEIGHT 110500 Kg

WEIGHT OF OIL 37200 Kg

TOTAL WEIGHT 188500 Kg

OIL QUANTITY 43900 lit


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GENERATOR TRANSFORMER(166 MVA UNIT-IV)

RATING 240MVA

TYPE OF COOLING ON/OB/OFB

TEMP OF OIL 45 C

TEMP WINDING 60 C

VOLTS AT NO LOAD HV-236000

LV-A5750

LINE AMPERES HV-587 A

LV-8798 PHASE THREE

FREQUENCY 50 HZ

IMPEDANCE VOLTAGE 15.55%

VECTOR GROUP Y DELTA

CORE AND WINDING WEIGHT 138800 Kg

WEIGHT OF OIL 37850 Kg

TOTAL WEIGHT 234000 Kg

OIL QUANTITY 42500 lit

GUARANTEED MAX TEMP 45 C DIVISION KERELA

YEAR 1977


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UNIT AUXILIARY TRANSFORMER (UAT)

Unit I & V- 12.5 MVA

The UAT draws its input from the main bus-ducts. The total KVAcapacity of UAT required can be determined by assuming 0.85power factor & 90% efficiency for total auxiliary motor load. It issafe & desirable to provide about 20% excess capacity thencirculated to provide for miscellaneous auxiliaries & possibleincrease in auxiliary.

STATION TRANSFORMERIt is required to feed power to the auxiliaries during startups. Thistransformer is normally rated for initial auxiliary load requirementsof the unit in typical cases; this load is of the order of 60% of theload at full generating capacity. It is provided with on load tapchange to cater to the fluctuating voltage of the grid.

NEUTRAL GROUNDED TRANSFORMERThis transformer is connected with supply coming out of UAT instage-2. This is used to ground the excess voltage if occurs in thesecondary of UAT in spite of rated voltage.


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SWITCH YARD

As we know that electrical energy cant be stored like cells, so what we generate should be consumedinstantaneously. But as the load is not constants therefore we generate electricity according to need i.e.the generation depends upon load. The yard is the places from where the electricity is send outside. Ithas both outdoor and indoor equipments.

OUTDOOR EQUIPMENTS BUS BAR. LIGHTENING ARRESTER WAVE TRAP BREAKER CAPACITATIVE VOLTAGE TRANSFORMER

EARTHING ROD CURRENT TRANSFORMER. POTENTIAL TRANSFORMER LIGHTENING MASK

INDOOR EQUIPMENTS RELAYS. CONTROL PANELS CIRCUIT BREAKERS


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BUS BAR

Bus bars generally are of high conductive aluminum conforming to IS-5082 or copperof adequate cross section. Bus bar located in air insulated enclosures & segregated from allother components .Bus bar is preferably cover with polyurethane.

BY PASS BUS

This bus is a backup bus which comes handy when any of the buses become faulty. Whenany operation bus has fault, this bus is brought into circuit and then faulty line is removed thereby restoring healthy power line.

LIGHTENING ARRESTOR

It saves the transformer and reactor from over voltage and over currents. It grounds theoverload if there is fault on the line and it prevents the generator transformer.

WAVE TRAPWAVETRAP is connected in series with the power (transmission) line. It blocks the highfrequency carrier waves (24 KHz to 500 KHz) and let power waves (50 Hz - 60 Hz) to pass-through.

BREAKER

Circuit breaker is an arrangement by which we can break the circuit or flow of current. Acircuit breaker in station serves the same purpose as switch but it has many added andcomplex features. The basic construction of any circuit breaker requires the separation ofcontact in an insulating fluid that servers two functions:

extinguishes the arc drawn between the contacts when circuit breaker opens.

It provides adequate insulation between the contacts and from each contact to earth.


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EARTHING ROD

Normally un-galvanized mild steel flats are used for earthling. Separate earthing electrodesare provided to earth the lightening arrestor whereas the other equipments are earthed byconnecting their earth leads to the rid/ser of the ground mar.

CURRENT TRANSFORMERIt is essentially a step up transformer which step down the current to a known ratio. It is a typeof instrument transformer designed to provide a current in its secondary winding proportionalto the alternating current flowing in its primary.

POTENTIAL TRANSFORMER

It is essentially a step down transformer and it step downs the voltage to a known ratio.

RELAYS

Relay is a sensing device that makes your circuit ON or OFF. They detect the abnormalconditions in the electrical circuits by continuously measuring the electrical quantities, whichare different under normal and faulty conditions, like current, voltage frequency. Havingdetected the fault the relay operates to complete the trip circuit, which results in the openingof the circuit breakers and disconnect the faulty circuit.

There are different types of relays:

Current relay

Potential relay

Electromagnetic relay

Numerical relay etc.

AIR BREAK EARTHING SWITCH

The work of this equipment comes into picture when we want to shut down the supply formaintenance purpose. This help to neutralize the system from induced voltage from extra highvoltage. This induced power is up to 2KV in case of 400 KV lines.


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CONTROL & INSTRUMENTATION

INTRODUCTION

C&I LABS

CONTROL & MONITORING MECHENISM

PRESSURE MONITORING

TEMPERATURE MONITORING

FLOW MEASUREMENT

CONTROL VALVES


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INTRODUCTIONThis division basically calibrates various instruments and takescare of any faults occur in any of the auxiliaries in the plant.

Instrumentation can be well defined as a technology ofusing instruments to measure and control the physical andchemical properties of a material.

C&I LABSControl and Instrumentation Department has following labs:

Manometry Lab.

Protection and Interlocks Lab. Automation Lab. Electronics Lab. Water Treatment Plant. Furnaces Safety Supervisory System Lab


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THANKU

summer training report ntpc

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