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ntpc summer trainin Final Report

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BTPSSUMMER TRAINING REPORT

NAME-MANSI TIWARI BRANCH-ELECTRICALSCOLLEGE-APEEJAY COLLEGE OF ENGINEERING,SOHNA

BADARPUR THERMAL POWER STATION (A UNIT OF NTPC)

GURGAON ROLL NO-072023 SEMESTERIVTHTTHTHTHGTH

SUMMER TRAINING REPORT

BTPS

CERTIFICATE

This is to certify that MANSI TIWARI student of bachelor of Technology, Electricals, 3rd Year, APEEJAY COLLEGE OF ENGINEERING (SOHNA,GURGAON) has successfully completed her 34 days industrial Training at Badarpur Thermal Power Station, New Delhi from 29th June to 1st August 2009. She has completed the whole training as per the training report submitted by her.

Training Incharge BTPS/NTPC, Badarpur, New Delhi

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ACKNOWLEDGEMENTWith profound respect and gratitude, I take the opportunity to convey my thanks for permitting me to complete my training here. I extend my heartfelt thanks to Ms. Rachna Singh Bahal for providing me this opportunity to be a part of this esteemed organization. Im extremely grateful to all the technical staff of BTPS / NTPC for their co-operation and guidance that has helped me a lot during the course of training. I have learnt a lot working under them and I will always be indebted to them for this value addition in me. I would also like to thank the training incharge of APEEJAY COLLEGE OF ENGINEERING(SOHNA,GURGAON) and all the faculty members of electrical department for their effort of constant co-operation, which have been a significant factor in the accomplishment of my industrial training.

MANSI TIWARI APEEJAAY COLLEGE OF ENGINEERING SOHNA,GUR GAON

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ABOUT NTPCNTPC Limited today is one of the largest companies in India in terms of Market Capitalization and the single largest player in power sector, catering to approximately 30% of country's power needs. Set up in 1975 by Government of India, today it is a Navratna PSU with a strong workforce of 24,447 power professionals and an annual turnover of Rs.28, 750.7 Crores. The Company has 14 coal based and 7 gas based power plants across India with a total installed capacity of 26,404 MW. Several new projects are underway as the company has ambitious plans of achieving 75,000 MW installed capacity by 2017. NTPC Limited is the largest power generating company of India. A public sector company, it was incorporated in the year 1975 to accelerate power development in the country as a wholly owned company of the Government of India. At present, Government of India holds 89.5% of the total equity shares of the company and the balance 10.5% is held by FIIs, Domestic Banks, Public and others. Within a span of 33 years, NTPC has emerged as a truly national power company, with power generating facilities in all the major regions of the country.

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NTPC's core business is engineering, construction and operation of power generating plants. It also provides consultancy in the area of power plant constructions and power generation to companies in India and abroad.

Major Achievements of NTPC: 1) Largest thermal power generating company of India. 2) Sixth largest thermal power generator in the world. 3) Second most efficient utility in terms of capacity utilization. 4) One of the nine PSUs to be awarded by the status of Navratna.Page 6

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ABOUT BTPSBadarpur thermal power station started working in 1973 with a single 95MW 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 through GOIs Gazette Notification. Given below are the details of unit with the year they are installed.

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SUMMER TRAINING REPORT Address: Telephone: Fax: Installed Capacity Derated Capacity Location Coal Source Water Source Beneficiary States Unit Sizes Units Commissioned

BTPS

Transfer of BTPS to NTPC

Badarpur, New Delhi 110 044 (STD-011) 26949523 26949532 720 MW 705 MW New Delhi Jharia Coal Fields Agra Canal Delhi 3X95 MW 2X210 MW Unit I- 95 MW - July 1973 Unit II- 95 MW August 1974 Unit III- 95 MW March 1975 Unit IV - 210 MW December 1978 Unit V - 210 MW - December 1981 Ownership of BTPS was transferred to NTPC with effect from 01.06.2006 through GOIs Gazette Notification

Training at BTPSI was appointed to do 5 weeks training at this esteemed organization from 29th June to 1ST August 2009. I was assigned to visit various division of the plant, which were: Control & Instrumentation (C & I)Page 8

SUMMER TRAINING REPORT Electrical Maintenance Department - 1 (EMD-1) Electrical Maintenance Department -2 (EMD-2)

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This 5 weeks training was a very educational adventure for me. It was really amazing to see the plant by yourself and learn how electricity, which is one of our daily requirements of life, is produced. This report has been made by my experience at BTPS. The material in this report has been gathered from my textbook, senior student reports, manuals and power journals provided by training department. The specification and principles are as learned by me from the employees of each division of BTPS.

MANSI TIWARI

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THERMAL POWER PLANTThermal power plant converts the heal energy of coal to electrical energy. Coal is burnt in a boiler, which converts water into steam. The expansions of steam in turbine produces mechanical power, which drives the generator or the alternator. GENERAL STRUCTURE OF BTPS(750MW CAPACITY) :

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Schematic arrangement of steam power station1. Coal and ash handling arrangement. 2. Steam generating plant. 3. Steam turbine. 4.

Alternator.

5. Feed water. 6. Cooling arrangement.

Coal and ash handling plant :The coal is transported to the power station by road or rail and is stored in the coal storage plant. Storage of coal is primarily a matter of protection against coal strikes, failure of transportation system and general coal shortages. Form the coal storage plant, coal is delivered to the coal handling plant(CHP) where it is pulverized (i.e., crushed into small pieces) in order to increase its surface exposure, thus promoting rapid combustion without using large quantity of excess air. The main aim of CHP is to maintain the level of coal in the bunkers for smooth supply of coal to the boilers. The working conditions in CHP are dusty, dirty and often wet. The pulverized coal is fed to the boiler by bell conveyors. The coal is burnt in the boiler and the ash produced after the complete combustion of coal is removed to the ash handling plant and then delivered to the ash storage plant for disposal. The removal of the ash from the boiler furnace is necessary for proper burning of coal. It is worthwhile to give a passing reference to the amount of coal burnt and ash produced in a modern thermal power station. A 100 MW station operating at 5Q/ load factor may burn about 20,000 tons of coal per month and ash produced may be to the tune of IO% to 5% of coal fired i.e., 2,000 to 3,000 tons. In fact, in a thermal station, about 50% to 60% of the total operating cost consists of fuel purchasing and its handling.Page 11

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Following is the systematic diagram of the coal handling plant :

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CRUSHERS:In CHP crusher works on the principle of combination of impact and attrition crushing. In this type of crushing first coal breaks due to impact crushing and further it is scrubbed between two hard surfaces to get desired coal size. Some crushers work only on the principle of impact crushing. Generally these crushers are used before final crushers. The output size of coal affects the performance of CHP. The two hard surfaces of crusher are crucial parts. One of these is known as grinding plate and the other as rings, hammers etc. The link between crusher rotor and driver assembly is also crucial, as its failure will stop the crushing process.

WAGON TIPPLERS: In CHP generally there are two types of wagon tippler. They are known as rota type and rotary type. The main difference between these tipplers is that rotary type tippler has floating barrel and rota type tippler turns between two bearings. The drive linkages undergo cyclic loading and failure of these linkage stop the equipment operation, due to this unloading of coal cars affects, which drops the performance of CHP.

BUNKER - FEEDING CONVEYORS: CHP has number of conveyors but bunker-feeding conveyors play a vital role. The main aim of each CHP is to maintain bunker levels for smooth coal supply to boilers. As these conveyors feed the bunker their performance affects CHP performance. The drive linkages consists of gearbox and couplings. Failure of any part of the linkage will stop operation of feeding bunker level. So these parts are crucial parts of bunker feeding conveyors. The conveyor pulleys are also crucial parts.

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FEEDERS: The performance of feeders affects the efficiency of CHP. The feeders used in CHP are Apron Feeder, Vibrating Feeders, Roller Screens and Vibrating Screen Feeders etc. Generally vibrating feeders used, are of electromagnetic type. The springs, coils and suspension rods are the crucial parts. Weak coil springs that are not generating sufficient accelerating forces can also cause low speed and reduce the performance. In vibrating screen feeder have crucial part like beam and its members, drive linkages etc. Apron Feeders is sturdy machine, the crucial parts are fans, chain and rollers. The roller screens have crucial parts in drive linkages

Steam generating plant:The steam generating plant consists of boiler for the production of steam and other auxiliary equipment for the utilization of flue gases. a) Boiler:The heat of combustion of coal in the boiler is utilized to convert water into steam at high temperature and pressure. The flue gases from the boiler make their journey through super-heater, Economizer, air preheater and are finally exhausted to atmosphere through the chimney. b) Super-heater :The steam produced in the boiler is wet and is passed through a super-heater where it is dried and superheated (i.e., steam temperature is increased above that of boiling point of water) by the flue gases on their way to chimney. Superheating provides two principle benefits. Firstly, the overall efficiency is increased. Secondly, too much condensation in the last stages ofPage 15

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turbine (which would cause blade corrosion) is avoided. The superheated steam from the super-heater is fed to steam turbine through the main valve. c) Economizer:An economizer is essentially a feed water heater and derives heat from the flue gases for this purpose. The feed water is fed to the economizer before supplying to the boiler. The economizer extracts a part of heat of flue gases to increase the feed water temperature. d) Air-preheater.-

An air-pre heater increases the temperature of the air supplied for coal burning by deriving heat from flue gases. Air is drawn from the atmosphere by a forced draught fan and is passed through air-pre heater before supplying to the boiler furnace. The air pre heater extracts heat from flue gases and increases the temperature of air used for coal combustion. The principal benefits of preheating the air are increased thermal efficiency and increased steam capacity per square meter of boiler surface.

Steam turbine:The dry and superheated steam from the super heater is fed to the steam turbine through main valve. The heat energy of steam when passing over the blades of turbine is converted into mechanical energy. After giving heat energy to the turbine, the steam is exhausted to the condenser which condenses the exhausted steam by means of cold water circulation.

Alternator:The steam turbine is coupled to an alternator. The alternator converts mechanical energy of turbine into electrical energy. The electrical output from the alternator is delivered to the bus bars through transformer, circuit breakers and isolators.Page 16

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Feed water:The condensate from the condenser is used as feed water to the boiler. Some water may be lost in the cycle which is suitably made up from external source. The feed water on its way to the boiler is heated by water heaters and economizer. This helps in raising the overall efficiency of the plant.

Cooling arrangement:In order to improve the efficiency of the plant, the steam exhausted from the turbine is condensed by means of a condenser. Water is drawn from a natural source of supply such as a river, canal or lake and is circulated through the condenser. The circulating water takes up the heat of the exhausted steam and itself becomes hot. This hot water coming out from the condenser is discharged at a suitable location down the river. In case the availability of water from the source of supply is not assured throughout the year, cooling towers are used. During the scarcity of water in the river, hot water from the condenser is passed on to the cooling towers where it is cooled. The cold water from the cooling tower is reused in the condenser. NCHP feeds unit 4 and 5 (each of 210 MW capacity). It consists of double stream of conveyors of capacity 600 metric tones/hour. Except for stacking conveyors of 600mtph which is a single one wagon Tippler, four vibrating feeders of 300mtph each below the wagon tippler, two rotatry breakers of 600mtph each in secondary crusher house, one telescopic chute for stacking, two sets of reclaim hoppers, necessary transfer points and new rail tracks for the wagon tippler are provided. The wagon tippler is provided with integral weight bridge for recording the gross and true weight of the wagon and is located beyond the old marshalling yard, due to space Limitation only one wagon tippler is provided. Car pullers are used for placing the loaded wagon on the wagon tippler and removing the empty wagon.

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CONTROL & INSTRUMENTATIONThis division basically calibrates various instruments and takes care of any fault that occurs in any of the auxiliaries in the plant. It has the following Labs. 1. MANOMETRY LAB.2. PYROMETRY LAB. 3. AUTOMATION LAB. 4. PROTECTION & INTERLOCKING LAB. 5. TURBO SUPERVISORY INSTRUMENT LAB. 6. FURANCE SAFETY SUPERVISORY SYSTEM. 7.

ELECTRONICS TEST LAB.

This department is the brain of the plant because from relays to transmitters followed by the electronic computation chipsets and recorders and lastly the controlling circuitry, all fall under their responsibility.

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MANOMETRY LABVarious instruments used in this lab are:1. MANOMETER:It is a tube, which is bent, in the U shape. It is filled with a liquid. This device corresponds to a difference in the pressure across the two limbs. 2. BOURDON PRESSURE GUAGE:It is an oval section of tube. Its one end is fixed. It is provided with a pointer to indicate the pressure on a calibrated scale. It is of two types.

a. Spiral type-: It is used for measuring low pressure. It is more sensitive and is used where compactness is necessary. b. Helical type-: It is used for measuring high pressure. It is most sensitive and compact. Pointer may be mounted direct on end of helix which rotates, thus eliminating backlash error and lost motion.

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PYROMETRY LABThis lab consists of various temperature measuring instruments. LIQUID IN GLASS THERMOMETER:Mercury in the glass thermometer boils at 340 degree Celsius which limits the range of temperature that can be measured it is an L shaped thermometer, which is designed to reach all inaccessible places.1. The Bi-Metallic Strip:-

Bi-metal strips are composed of two metals, as the name implies, it is the one whose coefficients of linear expansion are dissimilar. These two metal plates are welded together as a sandwich. When heated, both metals expand, but the metal with greatest coefficient of linear expansion will expand more causing the sandwich to curl up or down depending on the position of this metal. (Refer Fig.).

2. ULTRA VOILET CENSOR:-

This device is used in furnace and it measures the intensity of ultraviolet rays present and according to the wave generated, a signal of the order of same is generated, which directly indicates the temperature in the furnace. This lab also has the responsibility of calibrating various instruments. Depending on the range of the device, the method to calibrate the device is adopted. The low range measuring devices are calibrated in the oil bath or just by using boiling water. The high temperature measuring device is calibrated in the small furnace.Page 22

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AUTOMATION LABThis lab deals in automating the existing equipment system, and feeding routes. Earlier, the old technology dealt with only data acquisition system and was known as primary. The modern technology or the secondary system is coupled with management information system. But this lab universally applies the pressure measuring instrument as the controlling force. Suppose, if in a motor the fall in pressure of lubricating oil directly implies to the heating of the machine then similarly fall in water pressure in the water pipe line implies overload or short circuit of the feed or circulating pump motors. However, the relays provided, are used only for the protection and interlocking. Once the measure is common, the pressure control circuit can easily be designed with single chip having multiple applications. Another point is the universality of the supply, the laws of the electronics state that it can be anywhere between 12 V and 35V. At the plant all control instruments are excited by 24V DC supply (0.5-2OA).

PROTECTION AND INTERLOCK LABThere are two kinds of protection system based on the voltage level at which they operate. These are discussed below:a) HIGH TENSION CONTROL CIRCUIT:For high-tension system the control system is excited by separate DC supply. For starting the circuit, condition should be in series with the starting coil of the equipment to energize it. The tripper is a coil, which deenergizes the start coil so that the equipment stops. The tripper derives signal from the tripping coil of the high tension tripping system. It should be noted that for tripping all the conditions should be in parallel. b) LOW TENSION CONTROL CIRCUIT: For low-tension circuits the control circuits are directly excited from the 0.415KV AC supply. The same circuit achieves both excitation and tripping. Here the tripping coil is provided for emergency tripping if thePage 23

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interconnection fails. This system is more prone to failure as it is excited from 415V of AC.

INTERLOCKING: It is basically interconnecting two or more equipment so that if one equipment fails other can perform the task. This type of interdependence is also created so that all the equipment connected together are started and shutdown in specific sequence to avoid damage. For protection of equipments tripping are provided for all the equipments. Tripping can be considered as the series of the instruction connected through OR gate. When a fault occurs and any one of the tripping is, satisfied a signal is sent to the relay, which trips the circuit. The main equipment of this lab are relays and circuit breakers. Some of the instruments used for protection are:1. RELAY: It is a protective device. It can detect wrong condition in electrical circuit by constantly measuring the electrical quantities flowing under normal & faulty condition. Some of the electrical quantities are voltage, current, phase angle and Velocity. After detecting the fault, the relay operates to complete the trip circuit, which results in the break up of circuit caused due to circuit breakers, and disconnects the faulty circuit. Two types of relays used in this lab are given below.a)

Current Relay: - It gets energized when the rated amount of current flows through it. It is always connected in series. Potential Relay: - It gets energized by voltage and has copper

b)

winding as the coil. It is always connected in parallel.2. FUSE: -

It is a short piece of metal inserted in the circuit, which melts if heavy current flows through it and thus breaks the circuit. Usually sliver is used as a fuse material because:-

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The expansion coefficient of sliver is very small. As a result, no critical fatigue occurs and thus the continuous full capacity normal current rating is assured for the long time.

b) The conductivity of the silver is unimpaired by the surges of the current that produces temperatures just near the melting point.c)

Silver fusible elements can be raised from normal operating temperature to vaporization much quicker than any other.

3. MINIATURE CIRCUIT BREAKERS: -

They consist of current carrying contacts, one is movable and the other is fixed. When a fault occurs, the contacts separate and an arc is struck between them. They are used with combination of the control circuit to:a) b) Enable the starting of plant and distributors. Protect the circuit in case of a fault.

The miniature circuit breakers that are used, employ three tripping mechanism as given below:a) Manual Trip: - Manual trip implies that the miniature current breaker can be

operated as an electrical switch.b) Thermal trip: - Thermal trip is the hi-metallic tripper when the circuit draws the

excess current, the contact between the two metals breakers rises due to temperature.c) Short Circuit Trip:-The short circuit or dec. Mag. Trip works in the case of short

circuit as the short circuit current is many times the rated current, it is allowed to flow through coil with movable aluminum core attached to the tripping spring. This on being energized with sufficiently large current pulls the core, which in turn releases the spring.

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FURANCE SAFETY SUPERVISORY SYSTEM LABThis lab has the responsibility of starting the fire in the furnace to enable the burning of coal. For first stage coal burners are in the front and rear of the furnace and for the second and third stage corner firing is employed. Unburnt coal is removed using forced draft fan. The temperature inside the boiler is 1100 degree Celsius and its height is 18 to 40m. It is made up of mild steel. An ultra violet sensor is employed in the furnace to measure the intensity of the ultra violet rays inside the furnace and according to it, signal in the same order of same mV is generated, which directly indicates the temperature of the furnace. For firing the furnace a 10 KV spark plug is operated for 10 seconds over a spray of diesel fuel and pre- heated air along each of the feeder mills. The furnace has six feeder mills each separated by warm air pipes fed from forced draft fans. In first stage indirect firing is employed that is feeder mills are not fed directly from coal but are fed from pulverized coal from bunkers. The furnace can operate on the minimum feed from three feeders but under no circumstances should any one of the intermediate mills be left out under operation, to prevent creation of pressure difference with in the furnace, which theaters to blast it.

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TURBO SUPERVISORY INSTRUMENTS LABThis lab takes of all the instruments, which are part of the turbo supervisory system to allow safe and proper operation of the turbine. Some of the turbine parameters that have to be monitored are as follows:a) TURBINE SPEED:The speed of the turbine is to be kept constant so that the frequency of the generated electricity is close to 50 Hz. The indicator of the speed gives us a remote indication of the speed when barring gear rotates the rotor. It gives a local and remote digital indication of the turbine speed, which in turn is given by the photoelectric pick up system. There is a white dot on the turbines, which reflect the light given by the photoelectric pick up device. The rate at which light is sensed is use to calculate the speed of turbine. There is indicator, which also set up alarm signal at 10% and 16% over speed. b) AXIAL SHIFT OF ROTOR: During the rotation of the turbine at high speeds where there is the wearing down of bearing, there is axial shift. Depending on the bearing which have become worn, thrust collar is given with respect to working pads, if this parameter is not monitored properly, then severe bubbling and mechanical interfaces can take place. The position of the thrust collar is taken by detector, which has two elements. There is variable type transducer and a bridge configuration. c) SHAFT ECCENTRICITY: Eccentricity is the deviation of the mass centre from the geometrical centre of the bearing case. It usually occurs in the rotor when there is a shut down. If it becomes large, then there will be a variation, which can be dangerous. To measure the eccentricity aPage 27

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passive and active magnetic reluctance type transducer in combination with bridge circuit in balance condition is used. In this case tolerance is of the order of 10 to 500 microns. d) BEARING VIBRATIONS:This vibration is to and fro motion of the machine under the influence of oscillatory force caused by unbalanced masses in the rotating system. This is one of the most vital parameter of the turbine and it has to be monitored continuously.

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EMD-IThe EMD-I section in BTPS is engaged in maintenance of motors and switchgears. MOTORS:Motors play a very important role in the operation of a power plant as most devices are run by it. The objective of this Chapter is to give an insight into the fundamentals of motor operation and starting .Motor are of various types. There are DC as well as AC motors. Both are used at different places according to the work required. These are further classified according to their construction. DC Motor Classification:>

Series motor

> Shunt motor > Compound motor AC Motor Classification:> Squirrel cage motor > Wound motor > Slip ring induction motor In a modern thermal power plant normally a three-phase squirrel cage Induction motor is used but some times a double wound motor is also used when we need a high starting torque e.g. in ball mills. THREE PHASE INDUCTION MOTOR:In a three phase induction motor, stator is connected to a three phase supply which produces a rotating magnetic field. Speed of rotation is proportional to main frequency and inversely proportional to the number of pairs of poles. N sync - 60 x supply frequency Pairs of poles. Stator can have concentric single layer windings with each coil side occupying one statorPage 29

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slot. In practice many types of stator winding may be encountered. Two of the most common types are illustrated in Fig. 58.A three phase Induction motor stator connected a 3 phase supply produces a rotating magnetic field whose speed is given by :Ns=120*f/p STATOR :Stator can have concentric single layer winding with each coil side occupying one stator slot. Two most common types of windings are. (1) Distributed winding: - This type of winding is distributed over a number of slots. (2) Double layer winding:- Each stator slot contains sides of two separate coils.

BEARING AND LUBRICATION:-

A good bearing is needed for trouble free operation of the motor. Since it is a very costly part of motor, a lot of care has to be taken by checking it at regular intervals. Damaged bearing may severally affect a motor, so lubrication plays important role. Two types of lubrication are used. (1) Oil Lubrication (2) Grease lubrication INSULATION:-

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Since winding play an important role in the operation of a motor. It has to be properly insulated from being short circuited and causing unnecessary damage. Previously class B insulation was being used but now better class F insulator is used.

TYPES OF INSULATION TYPES OF INSULATION Y A E B F H C

TEMPRATURE WITHSTANDING CAPACITY (0 C) 90 105 120 130 155 180

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BADARPUR THERMAL POWER STATION (A UNIT OF NTPC) BTPS NAME-MANSI TIWARI BRANCH-ELECTRICALS COLLEGE-APEEJAY COLLEGE OF ENGINEERING,SOHNA GURGAON ROLL NO-072023 SEMESTER-IVTHTTHTHTHGTH SUMMER TRAINING REPORT
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