REPORT ON MEJIA THERMAL POWER PLANT(DVC)

5/20/2018

REPORTONMEJIATHERMALPOWERPLANT(DVC)-slidepdf.com

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NAME:Pravin biswakarma JALPAIGURI GOVT ENGG COLLEGE ELECTRICAL ENGG DEPARTMENT DATE OF TRAINING: From 13th June,14 to 03th July,14

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VOCATIONAL TRAINING PROJECT REPORT ON MEJIA THERMAL POWER STATION (M.T.P.S),DAMODAR VALLEY CORPORATION(D.V.C)

ABOUT M.T.P.S Mejia

Thermal

Power

Station is

located at Durlovpur, Dist: Bankura, 26 km

from Durgapur city in West Bengal. Commissioned on 1996, MTPS is the largest thermal power plant, in terms of electricity generating capacity in the state of West Bengal as well as among other DVC power plants.

Power Plant: Mejia Thermal Power Station has an installed capacity of 2340 MW. The plant has 8 units under its operation. The individual units have the generating capacities as follows: Unit No. Generating Capacity

Commissioned on

U#1

210 MW

1996

U#2

210 MW

1998

U#3

210 MW

1999

U#4

210 MW

2005

U#5

250 MW

2008

U#6

250 MW

2009

U#7

500 MW

2010

U#8

500 MW

2010

Units 1 to 6 are collectively named as MTPS-phase1, while the extension of Units 7 & 8 is called MTPS-phase 2. All the units have boilers, turbines and generators manufactured by Bharat Heavy Electrical Limited (BHEL).


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SUBJECT OF TRAINING: THERMAL POWER STATION GENERATING TRAINING

PLACE OF TRAINING: DAMODAR VALLEY CORPORATION

Mejia Thermal Power Station P.O:MTPS,Dist:Bankura-722183,West Bengal Phone:03241-232201

FAX-03241-262231

ENGINEERS UNDER WHOM TRAINING IS PERFORMED: 1. Mr. Bidhayak Dutta (Deputy Chief Engg. Elec) 2. Mr. P.K Dubey (Training Advisor) DURATION OF TRAINING: 13

TH

TH

JUNE,2014 to 03 JULY,2014


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DAMODAR VALLEY CORPORATION Mejia Thermal Power Station P.O:MTPS,Dist:Bankura-722183,West Bengal Phone:03241-232201

FAX-03241-262231 th

Dated:29 March’2014

No.MT/PL/Voc.Trg./Vol.XII/1682 TO WHOM IT MAY CONCERN

This is to certify that Mr.Pravin Biswakarma, student of electrical engineering of Jalpaiguri Government Engineering College, Jalpaiguri-735102(W.B) undertook vocational training at Mejia Thermal Power Station, DVC, for the period of 21(Twenty One) days w.e.f 13.06.2014 under Electrical Dept., MTPS. During his training he has been found sincere, hard working and well disciplined.

.........................................

(Shri Bidhayak Dutta) The Dy Chief Engineer (Elect.) MTPS, DVC


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ACKNOWLEDGEMENT Any project is the fruitful outcome of the hard work of many. Through this document we would like to express our gratitude

towards those who supported us in making us an outcome from us.

Firstly, we would like to thank Shri. Bidhayak dutta(Deputy Chief Engg. Elec.). He inspite of his tremendous workload helped us admirably. Our humble thanks to Shri.P.K Dubey(Training Advisor) who guided us in each and every step till our completion of our training. We are thankful to them for their continued guidance and support with their vast pool of knowledge, which was essential for the completion of this project. Along the way , we were also ably supported and guided by staffs of the various departments. And like we mentioned, the help is even more credible, considering that the workload of the staff was immense.

We would also like to thank our friends and family for providing encouragement and moral support at every step. We recognise

everybody’s helping hand.


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CONTENTS SL NO 1

TOPIC INTRODUCTION AND HISTORY

2

OVERVIEW OF A POWER PLANT

3

ELECTRICAL SYSTEM a)

GENERATOR & AUXILIRIES

1. BASIC PRINCIPLE & CONSTRUCTION 2. EXCITATION SYSTEM 3. AVR 4. COOLING SYSTEM 5. PROTECTION SYSTEM 6. GENERATOR METERING & INSTUMENTATION 7. ELECTRICAL PROTECTION AND SAFETY INTERLOCKS

b) OVERVIEW OF GT, UT, UAT,UST, ST, SAT,SST, NGT c)

SWITCHYARD 1.VARIOUS COMPONENTS 2.PROTECTION

d)

STATION GROUNDING SYSTEM

e)

MOTORS

f)

DC SYSTEM

g)

DG SET


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INTRODUCTION & HISTORY

DVC, a legacy to the people of India, emerged as a culmination of attempts made over a whole century to control the wild and erratic Damodar river. The river spans over an area 2

of 25,000 km covering the states of Bihar (now Jharkhand) & West Bengal. th

Damodar Valley Corporation was established on 7 July 1948.It is one of the most reputate company in the eastern zone of India. DVC is established on Damodar river. It also consists of the Durgapur Thermal Power Plant in Durgapur. The hydel project in Mython is one of the most flourishing part of DVC. The MTPS(Mejia Thermal Power Station) under DVC is one of the largest thermal power plant in West Bengal. It is one of the four thermal power stations of DVC in the states of West Bengal. The total power plant campus area is surrounded by boundary walls and is basically divided into two major parts, first power plant area itself and second is the colony area for the residence

and other facilities for MTPS’s employees.

SALIENT FEATURES Location: Mejia in Bankura District in West Bengal. Installed Capacity: (210*4 MW+250*2 MW + 500*2 MW)=2340MW Coal source: B.C.C.L and E.C.L, also imported from Indonesia Fuel quantity:126 TPH(for unit 1 to 4 only) 150 TPH(for unit 5 and 6 only) 272 TPH (for unit-7 only) Height of chimney: 220m[205+15](for unit 1 to 6) 279m (for phase II) Water source: DAMODAR RIVER Beneficiary State: WEST BENGAL, JHARKHAND


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OVERVIEW OF POWER PLANT OPERATION A power plant is basically an energy conversion mechanism. Thermal power plants operate on modified Rankin Cycle with reheating and superheating. In essence , it is modified from of the basic steam cycle to increase the cycle efficiency. Coal is burnt in a boiler, which converts water into steam. The steam is expanded in a turbine, which produces mechanical power driving the alternator coupled to the turbine. The working of the power is divided into four main circuits:  Fuel and ash circuit.  Air and Fuel gas circuit.  Feed water and steam circuit.  Cooling water circuit.

THE ENERGY CONVERSION  Chemical energy to  Heat energy to

heat energy

kinetic energy

 Mechanical energy

---- In Boiler ---- In Turbine

to electrical energy --- In Generator

FLUE GASES

WATER FUEL

THERMAL POWER PLANT

ELECTRICITY

AIR

ASH


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ENERGY FLOW DIAGRAM OF DIFFERENT PART :

CHEMICAL ENERGY

HEAT ENERGY

(COAL)

(STEAM) BOILER

HEAT ENERGY

MECHANICAL ENERGY

(STEAM)

(TURBINE) TURBINE

MECHANICAL ENERGY

ELECTRICAL ENERGY

(TURBINE)

(GENERATOR) GENERATOR


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OVER VIEW OF A POWER PLANT


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VARIOUS COMPONENTS OF A POWER PALNT: DEAERATOR: The condensed water from the condenser is taken to deaerator where the water is made free from oxygen mainly i.e. free from air. The deaerator is a direct heat exchanger because the steam from IPT is sprayed to the condensed water from the bottom and the water is sprayed from the top part of the deaerator. This results in deoxyfication i.e. removal of oxygen from the water.

BOILER FEED PUMPS (BFPs): The outlet of the deaerator is connected to boiler feed pumps, there are three BFP in a row out of which two are in running condition and one is at standby,in unit #1 to 6 all BFP are MDBFP,consumes highest power in the plant 4.6MW in full load and unit#7 and 8 one of these is MDBFP( motor driven), and other two are TDBFP(steam driven).MDBFP consumes the highest power in this plant i.e. 10MW. MDBFP is used only at the starting time for its huge power consumption.

HIGH PRESSURE HEATER: The HPHs are also mechanical heaters that receives the heating medium from exhaust of HPT and IPT. There are two HPH named as HPH#5 and HPH#6. HPH#5 receives steam from IPT and HPH#6 receives steam from HPT . The BFP outlet is connected to the HPH#5 and HPH#6 is connected to HPH#5. Steam of HPT and IPT heats the water up to 253 C and the pressure is also increased up to 175kg/sq. cm, which is then passes through economiser this done to increase the efficiency of the


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boiler. Extn. Steam Pressure to HPH#5: 16.65 kg/sq. cm and temp. 415C. Extn. Steam pressure to HPH#6: 42.84 kg/sq. cm. and temp. 337.8C.

ECONOMISER: Economiser is another heat exchanger type heater. Here the water from HPH comes to get more heated up for better steam production and high enthalpy resulting in greater efficiency of the boiler and unit as well. The economiser receives the heat for heating the water from the flue gas. The flue gas which has very high temperature comes from air pre-heater to the economiser and heats up the water mechanically which finally reaches the boiler drum. Economiser inlet tepm. is 254C and outlet temp. is 315C.

BOILER DRUM: Boiler drum is the part of boiler where the de-mineralized water is stored and is inserted into the boiler through three BCW(Boiler circulating water pump). It is also houses the steam that is formed in the boiler. Water stored in the drum comes down to the top of the boiler and forms a “water ring ” which is then inserted into the boiler through the 6 water walls. Water walls are basically tubes along the walls of the furnace, it is here where the water is converted into steam at 130C and then the produced steam is taken back to the boiler drum. The drum has a propeller that rotates at high speed and makes the steam and water separated due to centrifugal force. The pressure of boiler drum is 192 kg/sq. cm and must be always maintained. Water in the drum comes from feed control station via economiser.

FURNACE AND BOILER:-Boiler is the main section where the steam is produced by coal combustion. Boiler consists of boiler drum, water walls, wind box, heaters. The boiler has 8 elevations named as A-B-C-D-E-F-G-H. Coal is inserted into the boiler from AB-C-D-E-F-G-H. There is 8 mills for feeding the pulverized coal to the furnace. Each mill has 4 pipe for firing in the four corners of furnace. Furnace is divided into two parts named as first pass and second pass. The combustion takes place in the first pass and the heating of steam through SH takes place in the second pass.

SUPER HEATER: The important point is to be always kept in mind that all the heaters that are used in thermal power plant are mechanical type heaters i.e. heat exchanged phenomena heats one medium by exchanging heat from another hotter medium. Super heaters are actually suspended pipes in the second pass section of the boiler, the flue gas http://slidepdf.com/reader/full/report-on-mejia-thermal-power-plantdvc

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having very high temperature heats the steam that comes from the drum before they hit the turbines to a temperature up to 540 C. The pressure of steam is kept constant when passing through super heater. The main concept behind making the steam super heated is to make the steam absolutely moisture free before they hit the turbine because moisture content of steam will damage the blades of turbine by corrosion.

TURBINE SECTION: The turbine section consists of three parts named as HPT(High pressure turbine), IPT(Intermediate pressure turbine),LPT(Low pressure turbine). The superheated steam from the Superheater enters the HPT and hits the blades at 176.2 kg/sq. cm and 540C and rotates the shaft. The exhaust steam of HPT is taken to IPT through a reheating section called Reheater(RH) for enabling the steam to regain its previous steps. The exhaust steam of IPT enters LPT directly. The exhaust of LPT is taken to condenser.

CONDENSER: The exhaust steam of LPT is fed to the condenser where the steam is converted into water by the principle of condensation. The condenser has three extraction pumps known as Condensate Extraction Pumps (CEP-A, CEP-B, CEP-C). These pumps create a negative pressure i.e. vacuum in the condenser for better suction of the condensate. The outlet of the CEP is connected to low pressure heater(LPH); where the temperature of condensed water is raised to little higher temperature for


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better efficiency of overall unit.

FLUE GAS PATH : AIR PREHEATER: The flue gas produced as a result of combustion of fossil fuel in the furnace is taken to the air pre heater. The air pre heater is used to heat up the atmospheric air to make hot air used for combustion and transport of coal dust from mill to furnace; which called secondary air. This heater has a unique process of heating, it has a shaft attached to rotating wheel type structure(like turbine but arrangement blades are different). Atmospheric air are sucked by FD fans passes through one side of the rotating shaft and the hot flue gas passes through another side. This way heat of the flue gas gets transferred to the atmospheric air and gets heated. There are two air pre heaters for each unit named as AH-A and AH-B.

ELECTROSTATIC PRECIPITATOR (ESP) :Under government rules and regulation for industrial pollution control, ESP is must to each and every industry which deals high ash as residing. An electrostatic precipitator is a large , industrial emission-control unit. It is used in industries like thermal power plant, cement, paper, chemicals, metallurgical industries etc, which emit particles. In the thermal power plant it is designed to trap and remove ash particle from the exhaust gas http://slidepdf.com/reader/full/report-on-mejia-thermal-power-plantdvc

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of boiler. Clean gas, up to 99.9% cleaner than when it enter is then passes out of the precipitators. collecting electrode

weakest field

Emitting electrode

WORKING PRINCIPLE OF ESP

An ESP is a chamber in which flue gas from the furnace is forced into FD fans. Electrostatic precipitation is a physical process by which particles suspended in gas stream are charged electrically, and under the influenced of electric field are separated from the gas stream. The precipitation system consists of negatively charged high voltage discharged electrode wire suspended amidst positively charged collecting electrode surfaces. At a very high DC voltage of the order of 20KV-35 KV, a corona discharged occurs close to the negative electrode, setting up an electric field between the emitter and the charged surface. When the particle laden gas passes through the ESP fields, the gas close to the negative electrode is thus ionised upon passing through the corona . As the negative ions and electrons migrate towards the charged surface, they in turn charge the passing particle. The electrostatic field then draws the particles to the collector surface where they are deposited. Periodically, the collected particles are removed from the collecting surface by rapping or vibrating the collector to dislodge the particles. The dislodged particles drop below the electrical treatment zone and are collected through hoppers for ultimate disposal. The major components that accomplished above activities in ESP are as follows:


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•

High voltage discharge electrodes

•

Grounded collecting electrodes

•

Rapping systems

Power supplies and control components • Hoppers •

In practice the ESP shall consists of several such fields in series in the direction of gas flow. There may be two or more parallel passes of such series combination to meet the desire level of dust removal from the flue gas . Here four passes and 72 fields are in place.


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DRAFT FANS: There are basically three types of fans in a thermal power plant. i. ii. iii.

INDUCED DRAFT (ID FAN) FORCED DRAFT FAN (FA FAN) PRIMARY AIR FAN (PA FAN)

INDUCED DRAFT FAN/ ID FAN: This fan is used to create negative pressure in the furnace i.e. furnace pressure is lower than atmospheric pressure, as a result of which fire balls inside the furnace can not come out of the furnace.ID fans also drives the flue gas through out its path and finally ejects it out of chimney. It sucks air from the furnace and ejects it to the atmosphere. Mechanically ID fan is coupled with one 3-ph synchronous type motor. It is the only synchronous motor in the power plant because it gives more accurate control to its speed by V/f method for maintaining negative pressure as controlling of negative pressure is the most vital factor in any thermal power plant. There are two ID fan for each unit.

FORCED DRAFT FAN:Unlike ID fan, the FD fan is meant for creating positive pressure in the furnace and also supplies air from PA fan and secondary air for combustion. The FD fan takes air from atmosphere and expel it to the plant (i.e. in the furnace, wind box etc).Mechanically FD fan consist of one 3-ph induction motor, main bearing (antifriction bearing) and lube oil system.

PRIMARY AIR FAN/PA FAN: - Primary air fan is used for mixing of cold air of FD fan outlet with hot air of air pre-heater outlet. The main function of this is to transport pulverised coal from the mill to furnace. Mixing of hot air and cold air is necessary because it is needed to maintain the temperature of the pulverised coal from 80C to 90C for better transport of coal and better combustion in the furnace. Mechanically the construction of PA fan is same as FD fan.


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The Electrical System:- The electrical system basically starts at the turbo alternator and through the GT(generator transformer) to the switchyard and finally to the transmission lines. In between the network consists of many isolators, circuit breakers, CT, PT and other mechanisms. At MTPS the turbo alternator generates a voltage of 15.75KV(Unit#1/2/3/4),16.6KV(Unit#5/6), 21 KV( Phase II). The GTs steps this up to 220 KV(400KV for Phase II). The transmission is to Kalyaneswari ,Burnpur,Borjora,Durgapur and for phase IIthe transmission is to Mython, DSTPS, Jamshedpur.

Therefore the electrical system is : For Unit#1 to 6 :

Generator

GT

220 KV switchyard

Transmission Lines

GT

400 KV switchyard

Transmission Lines

For Unit#7 and 8:

Generator

Apart from these, the electrical system is intricately intertwined with the entire plant, considering that the entire protection and control is somehow done electrically.


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GENERATOR BASIC PRINCIPLE AND CONSTRUCTION: Principle: Generator converts mechanical power into electrical form and feeds it into the power system network . The working principle behind the operation of generator is

Faraday’s Laws of electromagnetic induction. The induced alternating voltage in a generator can be expressed as-

E=4.44fTΦ Volt Where, E= Voltage induced in volt. f=frequency of rotation in Hz. T=No. of turns

Φ=flux per pole in Wb.

The frequency of the alternating voltage is given by the following equation f=PNs/2 where, f=freq in Hz. P=no. of poles Ns=revolution/sec.

Components of Generator: The main components of a Generator are: 1.Stator

2.Rotor

3.Bearing and lubrication

4.Terminal Bushing and Bus duct

5.Excitation system

6. Slip ring and Brush gear assembly

7.Cooling system

8. Sealing system


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Stator: The stator embodies the core, stator winding and hydrogen coolers and provides a gas tight enclosure for hydrogen gas. It comprises of an inner and an outer frame. The outer frame is a rigid fabricated structure of welded steel plates capable of bearing the

pressure due to minor explosion of H₂ within the casing. Within the cylindrical barrel, a fixed cage is formed by grider built circular and axial ribs. These ribs divide the yoke into annular components through which cooling gas flows into radial ducts in the stator core and

TURBO GENERATOR


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Exchanges heat in the Hydrogen gas coolers housed horizontally parallel to the rotor shaft in the frame. The inner cage is usually fixed to the yoke by an arrangement of springs to dampen vibration. Rigid end shields close the stator ends and supports and shaft seals.

ROTOR: The rotor forms the rotating magnetic poles of the generator. This is cylindrical type and constructed form a cast Chromium , Nickel, Molybdenum and Vanadium steel through several stages of machining. Slots are machined on the outer surface to incorporate windings . Holes are also drilled for ventilation purposes. High grade copper with 0.03% to 1% silver is used for the windings with layers of mica or epoxy impregnated glass cloth as the insulation. A mechanically strong insulation (e.g. micanite) is used for lining the slots. With increase in generator capacity rotor windings used to carry a fairly high direct current for sufficient magnetic strength. This higher loading causes considerable amount of heat loss and large rotors incorporate combination of hollow conductors with slots or holes arranged to provide for circulation of the cooling gas through the actual conductors by gap pick up method .Due to very high rotational speed centrifugal force tries to lift the winding out of the slots. So they are contained in proper place by duralumin wedges. The end turns outside the slots are covered by non-magnetic steel retaining end rings and are secured to the rotor body. The end winding are insulated from retaining rings with the help of glass epoxy molded segments. The retaining ring is a single piece forging which protects the rotor end winding from high centrifugal force.

EXCITATION SYSTEM OF TURBO GENERATOR:The purpose of excitation system is to continuously provide the appropriate amount of D.C field current to the generator field winding. The excitation system is required to function reliably under the following conditions of the generator and the system to which it is connected . i)During start up of the generator. ii)During steady state operating condition. iii)At the time of transient disturbances (due to sudden applications or removal of load). iv)During prolonged system disturbances. The simplest case is that of during start up when the generator is running at rated speed with generator circuit breaker open(armature open circuited). The terminal voltage will increase with the increase in field current. Amount of field current


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required will be a function of only the terminal voltage. Because of magnetic saturation more field current will be required to produce an increment of armature voltage at high voltage than at low voltage. This will be governed by open circuit characteristics(O.C.C) of the machine. After the closing of generator circuit breaker the machine is connected to the system and operates in parallel with other machines connected to the system. The amount of field current required will be a function of the terminal voltage as before and also the load current and the power factor. This will be governed by the V-curves of the machine. Unlike the previous case if the generator is connected to a large system change in excitation current controls the reactive power(VAR) and the power factor only with a very minor influence of the terminal voltage. More severe duty the excitation system requires to perform upon is during system disturbances. At the time of transient disturbances the generator voltage may dip or rise momentarily. The excitation system must response fast to correct this quickly and stably. During prolonged disturbances(which may last from several seconds to several minutes) the excitation system may require to operate at it maximum or ceiling output. Thus properly designed excitation system should permit a)Close control of the generator voltage to match closely to the system voltage before synchronization. b)Close control of VAR after synchronization of the machine, without loss of stability or overheating of the field system. c)Operation of the system at its maximum or ceiling at the time of disturbances in the system.

DEVELOPEMENT OF EXCITATION SYSTEM: With increase in generator capacity and complexity of interconnection in power system, improved techniques in generator excitation have been developed with the aim to achieve higher capacity, ideal rate of response, simplicity, reliability, accuracy, sensitivity etc. In the earlier designs several concepts govern the majority of the excitation system, such as a) Exciters were commutator type and self excited. b) Exciters were shaft driven and motor driven rotating machines. c) Voltage regulators included magnetic or rotating amplifiers or combination of both. d) Manual control was by means of a rheostat. Next generation of excitation system introduced newer concepts. Some of which were a) Use of semiconductors for rectification.


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b) AC(automatic) voltage regulator with transistor pre-amplifiers and thyristors . c) New concepts of manual control. d) Elimination of commutators. e) New physical arrangements, f) New maintenances procedures . Present day excitation system have been promoted by a) Capacity to meet very high values of excitation suitable for unit capacities as high as 500MW or even more. b) Use of HF AC exciters as source of powers. c) Use of digital technologies for control, protection and switching. d) Higher stability unit and excellent performance during transient and fault conditions. e) Elimination of carbon brushes in brushless excitation system.

TYPES OF EXCITATION SYSTEM:The types of excitation system are i) DC excitation ii) Static excitation iii) Brushless excitation In MTPS Carbon Brush Excitation is used in Unit#1 to 4 and in Unit#5to 8 brushless excitation system is used.

BRUSHLESS EXCITATION:Supply of high current by means of carbon brush involves considerable operational and maintenance problems. These problems are eliminated in brushless excitation system which consists of AC main exciter ,a PMG, a rotating noncontrolled rectifiers, all mounted on the T.G shaft and static AVR. Field of the PMG which is permanent salient pole magnet rotates along with the generator shaft and generates permanent voltage (usually 400 v at 400 Hz freq.) at the stator windings. These outputs from the PMG is connected to the thyristors located in the AVR panel. The controlled DC output from the AVR panel is connected to the stationary field of the main exciter. The output from the rotating armature is connected to the diodes placed along with the rotating at the same speed that of the rotating armature of the exciter and generator field winding. Thus there is no flow of current between any moving part and stationary part and hence they use of brush gear is eliminated. The diodes are arranged on rectifier wheels in a three phase configuration .These are protected with fuse and RC network.


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During operation the fuses are monitored with the help of stroboscope. The entire arrangement is totally enclosed and the hot air is cooled in two or more cooler arranged alongside the exciter. Apart from the fuse monitoring unit, other features provided in brushless excitation system are ground fault detection,field current measurements etc.

AUTOMATIC VOLTAGE REGULATOR(AVR):Automatic voltage regulator (AVR) is the heart of excitation system of generator. Now a days the AVR uses semiconductor elements to achieve high reliability with very fast response. It has two independent channels, the Auto channel with closed loop voltage regulation and the Manual channel with open loop regulation. The two channels of the voltage regulator are designed for operation either on i) a station auxiliary AC power supply and ii) power supply from generator terminal or pilot exciter as the case may be. Both the auto and manual channels consist of a power part and a control part. Some of the salient features of AVR are : a) Capability of maintaining constant terminal voltage over a wide operating range and maintaining proper share of reactive load among the parallel running machines. b) Provision for raising the excitation level quickly (field forcing ) in case of fault or voltage dip to increase the transient stability limit of the system. c) In corporation of suitable circuitry to make the reference voltage as a linear function of frequency or turbo generator up to the edge frequency can be set depending on the requirement and constant reference voltage beyond edge frequency.

d) Provision of automatic follow up circuit to supervise and match the firing angles of the pulses in auto-channel and manual channel so that the disturbance on the generator terminal is minimum during transfer from auto regulation to manual regulation. e) Provision of stator current limiter , rotor current limiter and rotor angle limiter circuits for optimum utilisation of the lagging and leading reactive capabilities of the generator. f) Provision of automatic transformer from auto regulation to manual regulation in case of measuring PT fuse failure or some internal faults in the auto channel. g) Facility for remote control of voltage both in auto and manual channel.


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Generator Cooling and Sealing System:- STATOR WATER SYSTEM  

Stator water-cooling is a closed loop system There are two full capacity single stage centrifugal pumps with change over facility 3Ph.415V A.C motors drive the pumps



 





The stator water cooler is shell and tube type heat exchanger DM water flows through shell There are two mechanical filters and one magnetic filter Mechanical filters are of wire mesh type Magnetic filter is having permanent magnet

GAS SYSTEM Generator gas system constitutes of hydrogen gas used to cool the rotor and certain parts of stator. H₂-air mixture is explosive. So filling the Generator with H₂ by replacing air which is dangerous. So initially air is replaced by CO₂ and since CO₂ is heavier than air CO₂ is being filled from the bottom. Purging of air with CO₂ is being done till the purity of CO₂.

Cooling fans- Propeller type cooling fans at both the ends of rotor are provided for forced

circulation of H₂(H₂ cooled machines ) or air(air cooled machines )inside the generator. Fan hubs are made from alloy steel forgoing and are shrunk fitted on the rotor shaft. The alloy steel cast fan blades are fixed on the fan hub throughout its periphery with the help of strength alloy steel non-magnetic conical pins. These fan blades are easily removable from the hub. Fan shields are provided to guide the gas flow. Fan shields are fixed to the end shields.


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SPECIFICATION OF TURBO GENERATOR:For unit#1 to 4

KW:210MW p.f:0.85 lag KVA:247,000 Stator voltage:15.75 KV Stator ampere:9050 A Rotor voltage:310 V Rotor ampere:2500A Rpm:3000 Frequency:50 Hz Connection: Y Y Coolant: Water & Hydrogen Gas pressure: 3.5 bar(G) Insulation class: F Specification: IS:5422 IEC:34 For unit#5 and 6

KW:250MW p.f:0.85 lag KVA:294100 Stator voltage:16.5 KV Stator ampere:10291 A Rotor voltage:292V Rotor ampere:2395A Rpm:3000 Frequency:50 Hz Connection: Y Y Coolant: Hydrogen Gas pressure: 3 bar(G) Insulation class: F Specification: IS:5422 IEC:34


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For Unit#7 and 8

KW:500 MW p.f:0.85 lag KVA:588,000 Stator voltage:21 KV Stator ampere:16,200 A Rotor voltage:340 V Rotor ampere:4040 A Rpm:3000 Frequency:50 Hz Connection: Y Y Coolant: Water & Hydrogen Gas pressure: 3.5 bar(G) Insulation class: F Specification: IS:5422 IEC:34

SPECIFICATION OF PILOT & MAIN EXCITER(Unit#5 & 6) Apparent Power:

Main Exciter --

Pilot Exciter 35KVA

Active Power:

1344KW

--

Current:

3200A

105A

Voltage:

420V

220+/-22V

Speed:

50/S

50/S

Freequency:

150Hz

400Hz

SPECIFICATION OF PMG(Unit#7 & 8):KW:39 KVA:65 Volts:220 Amps:195 Rpm:3000 Phase:3 Coolant: Air Insulation Class: F


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Connection: Y Y Y Y YYYY Specification: IFC-34

SPECIFICATION OF BRUSHLESS EXCITER(Unit#7& 8):KW:3780 Volts DC:600 Amps DC:6300 Excitation Volts DC:107 Excitation Amps DC:142 Rpm:3000 Coolant: Air Insulation Class: F Specification: IFC-34

GENERATOR PROTECTION:With the ever increasing size of the generator cost of the machine, the expenses for repair and loss of energy during the outage of the machine are very high. Hence it is necessary to provide a reliable elaborate protection system to safeguard against damage and loss of generation and ensure long life of the machine. Generator protection concerns especially the electrical protection of machines and associated circuits. The purpose of generator protection is to provide protection against abnormal operating condition and during fault condition. In the first case the machine and the associated circuit may be in order but the operating parameters (load, frequency, temperature) and beyond the specified limits. Such abnormal running condition would result in gradual deterioration and ultimately lead to failure of the generator. It may be possible to correct the running of the generator. It may be possible to correct the running condition after the protective relay gives an alarm, there by avoiding the loss of revenue and damage of the machine. In the later case , it is necessary to restrict the damage of the machine and associate circuit to a minimum by taking it out from the service.

PROTECTION UNDER ABNORMAL RUNNING CONDITIONS: - a)Over current protection: The over current protection is used in generator protection against external fault as back up protection. Normally external short circuits are cleared


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by protection of the faulty section and are not dangerous to the generator. If this protection fails the short circuit current contributed by the generator is normally higher than the rated current of the generator and caused over heating of the stator, hence the generators are provided with back up over current protection which is usually definite time lag over current relay. b)Over load protection: Persistent over load in rotor and stator circuit cause heating of winding and temperature rise of the machine. Permissible duration of the stator and rotor over load depends upon the class of insulation, thermal time constant, cooling of the machine and is usually recommended by the manufacturer. Beyond these limits the running of the machine is not recommended and over load protection thermal relays fed by current transformer or thermal sensors are provided. c)Over voltage protection: The over voltage at the generator terminals may be caused by sudden drop of load and AVR malfunctioning. High voltage surges in the system (switching surges or lightning) may also cause over voltage at the generator terminals. Modern high speed voltage regulators adjust the excitation current to take care against the high voltage due to load rejection. Lightning arresters connected across the generator transformers terminals take care of the sudden high voltages due to external surges. As such no special protection against generator high voltage may be needed. Further protection provided against high magnetic flux takes care of dangerous increase of voltage. d)High flux density: High flux density in the machine causes saturation core leading to over heating in the iron core of both the generator and the transformer due to increased iron losses and additional losses from the eddy currents. High magnetic flux density may occur because of over excitation at no load or due to low frequency running. A relay which operates on V/f (volts per Hz) basis is recommended as a preventive measure for protection against high flux densities. e)Unbalance loading protection: Unbalance loading is caused by single phase short circuit out side the generator, opening of the one of the contacts of the generator circuit breaker snapping of conductors in the switchyard or excessive single phase load. Unbalance load produces –ve phase sequence current which cause over heating of the rotor surface and mechanical vibration. Normally 10% of unbalance is permitted provided phase current do not exceed the rated values. For –ve phase sequence currents above 5-10% of rated value dangerous over heating of rotor is caused and protection against this is an essential requirement. The relay provided for this is an inverse characteristic


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with definite minimum time delay relay connected to a network which segregates the

–ve sequence current from the positive and zero sequence currents. The I2t characteristics of the relay is matched to the rotor heating characteristic. f)Loss of excitation protection: The loss of excitation in a synchronous machine may be caused by tripping of field circuit breaker or trouble in AVR. On loss of excitation the generator starts drawing reactive power from the grid instead of supplying it. The power factor of the generator becomes capacitive and as a result of this asynchronous running ( higher slip frequency) over heating of the rotor surface takes place. In case the generators connected to the system can not supply this reactive power there will be large voltage drop in the system leading to instability. The protection provided against loss of excitation is by an off-set Mho relay. It’s operating characteristics is so chosen that during extremely low excitation faults within the tripping zone. g) Loss of prime mover protection: In the event of loss of prime mover the generator operates as a motor and drives the prime mover itself. In some cases this condition could be very harmful as in the case of steam turbine sets where steam acts as coolant, maintaining the turbine blades at a constant temperature and the failure of steam results in over heating due to friction and windage loss with subsequent distortion of the turbine blade. This can be sensed by a power relay with directional characteristics and the machine can be taken out of bar under the condition. Because of the same reason a continuous very low level of output from the thermal sets are not permissible. The generator breaker is tripped under this condition by the use of a relay measuring the electrical power output of the generator designed to operate when the power output faults below selected pre-set value. h)Pole slip protection: A generator may loss synchronism with system without losing the excitation. In this condition the machine may be subjected to severe mechanical torque and oscillation with consequent variation of current, voltage and power factor. If the angular displacement of the rotor exceeds the stable limit, the rotor will slip a pole pitch. If the disturbance persist the machine must be isolated from the system to prevent damage to the generator and to minimize power system disturbance. The pole slipping protection relay operates on the criteria that the angle of the generator EMF exceeds a certain fixed value with the operation of the reverse power relay. The occurrence of these criteria are counted and the machine is tripped out after a certain number of oscillations. These relays are capable of detecting the first pole slip condition when a slip, corresponding to the speed of pole slipping is in the range of +0.1% to +10% on a 50Hz


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basis. The protection must remain inoperative for steady state lading, power switching and correctly cleared system fault condition.

PROTECTION UNDER FAULT CONDITION:a)Stator short circuit: Short circuits are among the faults which cause the heaviest damage to the generator. Not only do they result in thermal damages such as the welding of the core laminations and burning of the winding but also result in possible mechanical damage like deformation of the ends of the coil. Very fast operating protection is required , otherwise the damage may be beyond repair. Differential protections, inter turn short circuit protections are the main protection against short circuits in stator winding. As back up protection for the same faults, minimum impedance and over current protections are used.

b)Differential protection: The protection is used for detection of internal faults in a specified zone defined by the CTs supplying the differential relay. For an unit connected system separate differential relays are provided for generator, generator transformer and unit transformer in addition to the overall differential protection. In order to restrict damage very high differential relay sensitivity is demanded but sensitivity is limited by CT errors, high inrush current during external fault and transformer tap changer variations.

c) Inter turn fault protection: Inter turn faults comprise of insulation failure between turns of the same winding or between the parallel winding of the same phase which can not be detected by longitudinal differential protection. Inter turn faults have commonly been disregarded on the basis that if the occur the will quickly develop into earth faults or phase to phase faults which will be detected by the sensitive protections provided for these faults. With this idea sometimes no specific protection for inter inter-turn fault is provided. However considering the risk of severe damage to the machine before the faults convert into above types of faults inter turn fault protection is recommended, In large machine as all the three windings are brought out separately it is possible to employ a system to transverse differential protection consisting of balanced current arrangement between current transformers connected in the line ends of the windings in which current in the parallel paths of the windings are compared. A bias system is always used as it is not possible to guarantee in advance that exact current sharing between windings take place.


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d) Back-up impedance protection: This protection is basically designed as back up protection for the part of the installation situated between the generator and the generator and unit transformers. A back up protection in the form of minimum impedance measurement is used, in which the current windings are connected to the CTs in the neutral connection of the generator and its voltage windings through a PT to the phase to phase terminal voltage. The pick up impedance is set to such a value that it is only energised by short circuits in the zone specified above does not respond to faults beyond the transformers.

e) Stator earth fault protection: The earth fault protection is the protection of the generator against damages caused by the failure of insulation to earth. Present practice of grounding the generator neutral is so designed that the earth fault current is limited within 5 and 10 AMPs. Fault current beyond this limit may caused serious damage to the core laminations. This leads to very high eddy current loss with resultant heating and melting of the core.

f) 95% stator earth fault protection: Inverse time voltage relay connected across the secondary of the high impedance neutral grounding transformer relay is used for protection of around 95% of the stator winding against earth fault.

g)100% stator earth fault protection: earth fault in the entire stator circuits are detected by a selective earth fault protection covering 100% of the stator windings. This 100% E/f relay monitors the whole stator winding by means of a coded signal current continuously injected in the generator winding through a coupling. Under normal running condition the signal current flows only in the stray capacitances of the directly connected system circuit. In case of an earth fault , this capacitance is bypassed and the monitoring current which is determined mainly by the resistance to earth increases. This increased current value and reproduction of the signal code are used for the operation of the relay. h)Rotor earth fault protection: Normally a single rotor earth fault is not so dangerous as the rotor circuit is unearthed and current at fault point is zero. So only alarm is provided on occurrence of first rotor earth fault. On occurrence of the second rotor earth fault between the points of fault the field winding gets short circuited. The current in field circuit increases, resulting in heating of the field circuit and the exciter. But the more dangerous is disturbed symmetry of magnetic circuit due to partial short circuited coils leading to mechanical unbalance. Severe vibration may seriously damage the machine. Thus the protection circuit should be so designed as to give an alarm in case of


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st

development of 1 rotor earth fault and it should trip the machine on the occurrence of nd

2 earth fault.

GENERATOR OPERATION:- The operation of the generator is concerned with the basic processes of synchronization, loading , voltage maintenance, stability and safe tripping/shutting down of the machine. In the power system the generator is required to operate in parallel with other running machines and to share both active and reactive power demand of the system.

Synchronization of generator: The process of interconnection of the generator with the grid to which a number of generators are already connected is known as synchronization. For successful synchronization and parallel operation of the generator the voltage, frequency and phase sequence of the incoming generator must be same as that of the grid(running system ). To determine the exact instant of synchronism synchroscope with three lamps is provided at the generator control desk. In some machine auto synchronization facility is also provided. Before rolling of the TG to match the speed of the machine corresponding to the grid frequency and increasing generator terminal voltage readiness of the machine itself and it is various auxiliaries are to be ensure. The synchronization process is to be in close co-ordination with the mechanical system of the power house. In general following operation and checking are to be carried out in steps before synchronization of the generator.

Before machine starts rolling check and ensureGenerator auxiliary system:a)The lube oil flow to generator bearings is adequate with correct pressure and temperature and there is no oil leakage.

b)Casing H₂ pressure is adequate and with required purity. There is no sign of drop in gas pressure. The machine may be synchronized at a lower H₂ pressure within allowable limit but in that case load is to be restricted as per the manufacturer’s recommendation. Hydrogen extractor fan is in service. c)Stator cooling water flow is established and distillate conductivity is below 5 micro mho-cm. d)Generator exciter end bearing pedestal insulation is clean and free from dust , dirt or oil.


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Generator bus duct: All the inspection windows are properly closed and there is no oil or water dropping over the duct. The dehumidifier blower is off.

Neutral grounding transformer(NGT): a)All the doors are properly closed and locked. b)There is no drop of oil or water on the cubicle.

Generator P.T and surge protection cubicles: a)All PT drums are completely rotated towards/inserted in service position and locked in that position and doors are properly closed. b)PT fuses are o.k. and tightly inserted within the grips. Door for the box containing fuses and terminal strip is closed.

ELECTRICAL PROTECTION AND SAFETY INTERLOCKS: Various failsafe protection and safety interlocks are provided in the power plant for safe starting, running and shutting down of electrical equipments. These interlocks play vital role to prevent or reduce damage of costly equipments during internal fault or fault in connected system/ equipments operational error as well as for safety of personnel and the system as a whole.

GENERATOR In general, it is based if generator protection relays initiate non-sequential trip mode(Class A) for unit isolation. However, sequential tripping (Class B) provides a better means of tripping a steam turbine generator on some abnormal operating condition where delayed tripping of the generator will not result in increased damage to the turbine, generator or other electrical equipment. The reason for sequentially tripping a steam turbine generator is to avoid the over-speed condition that results when the generator main breaker is tripped while steam is supplied to the turbine. Proper control logic is critical to the design of a sequential tripping scheme switches, trip oil system pressure switches etc) which is supervised by an electrical Low Forward Power relay/ Reserve Power relay. This relay is normally set to detect very low


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power levels and incorporates a brief time delay of the order of few seconds for added security.

It has been recommended that generator protective relays, initiates non-sequential trip mode for isolation of the unit due to electrical faults. Only devices protecting unit from an abnormal mechanical operating condition or an abnormal (not faulted) electrical condition or normal shut down should initiate a sequential trip. Class A Lockout Relay will operate for the following conditions indicating major

electrical faults in the Generator stator, Generator rotor, Generator Transformer and Unit Auxiliary Transformers and excitation transformer and associated field Breaker Cubicle and similar other faults as detailed below: a) Generator stator differential relay operated. b) Generator stator inter-turn differential relay operated. c) Generator Transformer differential operated d) Generator Transformer overall differential relay operated e) Unit auxiliary transformer differential relay operated f) Generator stator E/F relay(0-95%)operated

g) Generator stator E/F relay (95-100%) operated h) Generator rotor earth fault relay operated i) Loss of excitation relay operated j) Generator transformer restricted E/F relay operated k) Generator over voltage relay operated l) Generator reverse power relay operated m) Generator transformer over-fluxing relay operated n) Generator transformer back-up E/F relay operated o) UAT back-up E/F relay operated p) Back-up distance relay operated q) Generator negative sequence relay operated r) Bus differential protection relay operated s) GT buchholz relay operated t) UAT buchholz relay operated u) Thyristor bank failure v) Generator Neutral isolator open w) EBP pressed x) GT SPR(Sudden pressure relay) http://slidepdf.com/reader/full/report-on-mejia-thermal-power-plantdvc

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Class-B lockout relay will operate for the following conditions:

a)Boiler trip b) Turbine trip c)UAT backup O/C relay operated d)AVR protection Class-C lockout relay will operate for the following conditions:

a)Back-up distance relay operated stage I b)Generator negative sequence stage I c)GT breaker protection d)GT winding temperature/ oil temperature operated e) Under frequency relay operated

Unit trip sequence: The difference sequence of tripping shall be as mention below: a)Boiler to Turbine to Generator b)Turbine to Generator c)Generator to Turbine

Generator field breaker interlocks: Generator field breaker can only be closed if the following per missives are available a)Turbine is running at its rated speed(3000 rpm for thermal machine

with

+/- tolerance). b)To be detected by speed switch contact at ATRS cubicle c)All generator class-A lockout relay are in reset condition d)Field flushing system is healthy

Generator field breaker trip interlocks: Generator field breaker can trip through the following initiating contacts: a)Class-A relays operated

Generator field breaker manual trip block interlocks: When generator is in service manual tripping of field breaker is not permitted owing to loss of excitation and


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subsequent harmful effects on the machine. Operation of F8S relay indicate that generator is in service(connected in the grid) with its own breaker of bus coupler breaker. One NC contact of F8S relay is used in series with the manual tripping circuit of the field breaker.

Generator field breaker auto-trip block interlocks: When generator is in service, auto tripping (through Class-A lockout contacts) of field breaker is permitted only after opening of generator breaker or transfer B/C breaker as case may be and there by drop out of F8S relay to avoid momentary loss of excitation and subsequent harmful effect on the machine.

Single Line Diagram Of Generating Station(unit#5 and 6)


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SINGLE LINE DIAGRAM OF GENERATING STATION(UNIT-7)


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GENERATOR TRANSFORMER Transmission of power at generated voltage is not economical. The need for transformers is paramount for a power system considering the fact that transmission losses are minimum for high voltages where as a distribution has to be done at the relatively safe voltage. In essence the transformer ‘transforms ’ a voltage and current one level to a voltage and current at another level while keeping the frequency and power level unaltered. So generator output voltage is step up to the transmission voltage system voltage by a transformer known as Generator transformer(GT). Capacity of generator transformer is determined based on the MVA capacity of generator. The open type terminals of the HV bushing of the generator transformer are connected to switchyard conductor through GCB. The LV terminals are kept suitably enclosed to facilitated connection to generator bus duct. Cooling method adopted is OFAF. In MTPS Unit#1 to 6, GTs are single 3 phase transformer and in phase II, GTs are a bank of three single phase transformers . The only step up transformer is GT in this station.

GENERATOR TRANSFORMER http://slidepdf.com/reader/full/report-on-mejia-thermal-power-plantdvc

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Specification of GT:Unit# 1 to 4 Make: Type of cooling:

BHEL ONAN/ONAF/OFAF

Rating of HV(MVA):

150/200/250

Rating of LV(MVA):

150/200/250

Frequency(Hz):

50

Phase:

3

Connection symbol:

YNd1

No Load Voltage of HV(KV):

240

No Load Voltage of LV(KV):

15.75

Line Current of HV(Amp):

301/482/602

Line Current of LV(Amp):

3505/7340/9175

Temperature rise of oil(C):

40 over ambient of 50C 45 over ambient of 50C

Temperature rise of winding(C): Weight: Core and windings(kg):

139000

Complete Transformer including oil(kg): 38070 Transport(kg): 237100 Insulation level:

HV SI 750 LI 1050 LV LI 95 AC 50 H.V.N LI 170 AC 70

Unit# 5 and 6

Make: Type of cooling:

BHEL ONAN/ONAF/OFAF

Rating of HV(MVA):

109/252/315

Rating of LV(MVA):

109/252/315

Frequency(Hz):

50

Phase:

3

Connection symbol:

YNd1


220


16.5


757.77


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11022.14

Temperature rise of oil(C): Temperature rise of winding(C):

40 over ambient of 50C 45 over ambient of 50C

Weight: Core and windings(kg):

165000

Complete Transformer including oil(kg): 253250 Transport(kg):

180000

Oil quantity(lit):

57000

Insulation level:

HV SI 750 LI 1050 LV LI 95 AC 50 H.V.N LI 170 AC 70

Unit#7 and 8

Make:

BHEL

Type of cooling:

ONAN/ONAF/OFAF

Rating of HV(MVA):

120/160/200

Rating of LV(MVA):

120/160/200

Frequency(Hz):

50

Phase:

1

Connection symbol: No Load Voltage of HV(KV):

YNd11


420/√3 21 824.79 9523.8 40 over ambient of 50C 45 over ambient of 50C


153520

Complete Transformer including oil(kg):

257500

Transport(kg):

174900

Oil quantity(lit):

56220

Insulation level:

HV SI 1180 LI 1425-AC 38

No Load Voltage of LV(KV): Line Current of HV(Amp): Line Current of LV(Amp):

CHOPPED LI 1570 LV 125-AC 50


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UNIT TRANSFORMER: There is one unit transformer for each unit in phase ii. There are some machines whose operating voltage is 11kv.To supply these machines we have to step down the generating voltage. These can be done by unit transformer by tapping from generating terminal. Unit transformer step down the voltage 21kv to 11 kv. This is a three phase transformer. But, in case of unit#1to 6 there is no need of UT, because there is only two voltage level-6.6kv and 415v.

Specification of UT:Make:

BHEL

Type of cooling:

ONAF/ONAN

Rating of HV(MVA):

45/36

Rating of LV(MVA):

45/36

Frequency(Hz):

50

Phase:

3

Connection symbol:

Dyn1


21

No Load Voltage of LV(KV): Line Current of HV(Amp):

11.5 1238.64


2261.87

Temperature rise of oil(C): Temperature rise of winding(C): Weight: Core and windings(kg): Complete Transformer including oil(kg): Transport(kg): Oil quantity(lit): Insulation level:

40 over ambient of 50C 45 over ambient of 50C 40065 86205 50000 25580 HV LI 125-AC 50 LV LI 75-AC 28

Unit Auxiliary Transformer: The normal source of HV power to unit auxiliaries is unit auxiliary transformer. The sizing of the UAT is usually based on the total connected capacity of running unit auxiliaries i.e excluding the stand by drives. It is safe and desirable to provide about 20% excess


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capacity than calculated. With the help of UAT we stepped down the generated 15.75kv (in case of unit#1to4) and 16.6 kv(in case of unit#5,6) into 6.6kv to supply the 6.6kv auxiliary drives. But, in case of phase II UAT is used to stepped down the 11kv voltage into 3.3kv to supply the 3.3 kv machines and its high voltage terminal is connected to a UT and there is two UAT for each UT.

Specification of UAT:For Unit# 1to 4 Make:

Atlanta Electrical Pvt.Ltd.

Type of cooling:

ONAF/ONAN

Rating of HV(MVA): Rating of LV(MVA):

16/12.50 16/12.50

Frequency(Hz):

50

Phase:

3

Connection symbol:

Dyn11


15.7


6.9


586.5 /458.2


1338.8/1045.9

Temperature rise of oil(C): Temperature rise of winding(C): Weight: Core and windings(kg): Weight of oil(kg): Total weight(kg):

40C 45C

Oil quantity(litre): Insulation Level:

14300 8600 30500 7650

HV

:

95 KVP 38 KV rms

LV

:

30 KVP 20 KV rms

For Unit#5 and 6

Make:

BHEL

Type of cooling:

ONAF/ONAN

Rating of HV(MVA):

20/16

Rating of LV(MVA):

20/16


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Frequency(Hz):

50

Phase:

3

Connection symbol:

Dyn11

No Load Voltage of HV(KV): No Load Voltage of LV(KV):

16.5 6.9


699.81/559.85


1673.479/1338.783

Temperature rise of oil(C): Temperature rise of winding(C): Weight: Core and windings(kg):

50C

55C 20600

Weight of oil(kg): Total weight(kg):

15050 46300

Oil quantity(litre):

16900

Insulation Level: HV

:

95 KVP 38 KV rms

LV

:

30 KVP 20 KV rms

For Unit#7 and 8

Make:

BHEL

Type of cooling:

ONAF/ONAN

Rating of HV(MVA):

16/12.50

Rating of LV(MVA):

16/12.50

Frequency(Hz):

50

Phase: Connection symbol:

3 Dyn1


11


3.45


839.78/656.08


2677.57/2091.85


40C 45C


16700


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Weight of oil(kg):

9800

Total weight(kg):

40000

Oil quantity(litre):

11000

Insulation Level: HV

:

LI 75 KVP AC 28 KV rms

LV

:

LI 40 KVP AC 10 KV rms

DISTRIBUTION TRANSFORMER

To supply the 415v rated motors we use this distribution transformer which actually steps down the 6.6kv supply into 415v.Some of the distribution transformer are dry type i.e natural cooling system is used here.For each unit(1 to 6) there are 8 distribution transformer inside plant.

:RATING: Make:

BHEL

Type of Cooling:

AN

Rating(KVA):

1250

Rated Current H.V(Amps):

109.4

Rated Current L.V(Amps): Vector Group:

1666.7 DyN11

Model:

CAST RESIN DRY TYPE

Freequency:

50Hz 0

Temperature Rise Over 50 c Ambient 0

at 85.5% rated voltage:

80 c

Insulation level H.V:

75KVp/28KV rms

Insulation Class:

F

Weight(Kg):

5500

STATON SERVICE TRANSFORMER(SST): Normal source to the station auxiliaries and stand by source to the unit auxiliaries during start up and after tripping of the unit is Station Service transformer. Quantity of station Service transformers and there capacity depends upon the unit sizes and numbers. Each station service transformer shall be one hundred percent stand by of the other. Station service transformers shall cater to the simultaneous load demand due to start up power


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requirements for the largest unit, power requirement for the station auxiliaries required for running the station and power requirement for the unit auxiliaries of a running unit in the event of outage of the unit source of supply. There is three SST for unit#1 to 4 and two SST for unit#5 and 6.Its steps down 220 kv grid voltage to 6.6 kv voltage and supply two board-CAB(Common Auxialiary Board) and SEB(Start-up Emergency Board). For unit#1 to 4

Make:

BHEL

Type of cooling:

ONAF/ONAN

Rating of HV(MVA):

31.5/25.2

Rating of LV(MVA):

31.5/25.2

Frequency(Hz): Phase:

50 3

Connection symbol:

YNyn0d1


230

No Load Voltage of TV(KV):

11


6.6


79.1

Line Current of TV(Amp):

2635.8

Temperature rise of oil(C): Temperature rise of winding(C): Weight: Core and windings(kg): Weight of oil(kg): Total weight(kg):

40 45

34400 29550 214000

For unit#5 and 6

Make: Type of cooling:

BHEL ONAF/ONAN

Rating of HV(MVA):

40/25

Rating of LV(MVA):

25/15.625

Frequency(Hz):

50

Phase:

3

Connection symbol:

YNyn0yn0

No Load Voltage of HV(KV): No Load Voltage of LV1(KV): LV2(KV):

230 6.9 6.9


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100.408/62.755

Line Current of LV1(Amp) and LV2:

2091.848/1307.405

Temperature rise of oil(C):

40

Temperature rise of winding(C): Weight: Core and windings(kg): Weight of oil(kg): Total weight(kg):

45 48000 46000 132000

But in case of phase II this scheme is different and this is elaborated below-

STATION TRANSFORMER (ST): Normal source to the station auxiliaries and stand by source to the unit auxiliaries during start up and after tripping of the unit is Station transformer. Quantity of station transformers and there capacity depends upon the unit sizes and numbers. Each station transformer shall be one hundred percent stand by of the other. Station transformers shall cater to the simultaneous load demand due to start up power requirements for the largest unit, power requirement for the station auxiliaries required for running the station and power requirement for the unit auxiliaries of a running unit in the event of outage of the unit source of supply. We have two station transformer in 400kv switchyard. It steps down the 400kv grid voltage to 11kv voltage.

STATION AUXILIARY TRANSFORMER(SAT): Station auxiliary transformer is also a step down transformer. It steps down 11kv voltage to 3.3kv voltage. It is mainly used to supply the 3.3 kv machines. Its high voltage is

connected to the secondary of the ST. It’s use is similar to the UAT at starting condition and tripping condition. There is two SAT for each ST.

Specification of ST:Make:

BHEL

Type of cooling:

ONAN/ONAF

Rating of HV(MVA):

72/90

Rating of LV(MVA):

72/90

Frequency(Hz):

50

Phase:

3

Connection symbol:

Yn0 Yn0 Yn0


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400

No Load Voltage of LV1(KV):

11.5

LV2(KV):

11.5

Line Current of HV(Amp): Line Current of LV1(Amp):

130 2261.9

LV2(Amp):

2261.9

Temperature rise of oil(C): Temperature rise of winding(C): Weight: Core and windings(kg): Weight of oil(kg):

58450

Total weight(kg): Oil quantity(litre):

214000 67180

40 45 9769

Insulation level: HV :

LI 1300-AC38

LV 1:

LI 75- AC28

LV2:

LI 75-AC28

Make:

Specification of SAT:-

BHEL

Type of cooling:

ONAN/ONAF

Rating of HV(MVA):

16/12.50

Rating of LV(MVA):

16/12.50

Frequency(Hz):

50

Phase:

3

Connection symbol:

DyN1


11


3.45


839.78/656.08


2677.57/2091.85


40

45

UST & SST:- There are other two types of step-down 3 phase transformer for internal operation, known as UST and SST. UST is fed from UT switch board and SST is fed from ST


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switch board. These are dry type cast resin transformer. The voltage ratio is 11KV/433V for both the transformer. Air natural cooling and Dyn1 connection is used.

NGT (NEUTRAL GROUNDING TRANSFORMER):

The NGT is used to prevent the generator from earth faults. It comprises of primary winding and secondary winding, the secondary winding is connected with a low value resistance. When ever a earth fault arises heavy current flows to the primary winding and as a result an emf is induced in the secondary. The voltage drop across the resistance is sensed by the NGT relay and it actuates to actuate the GCB(generator circuit breaker) and thus the generator is tripped. Basically NGT is a step-down(21KV/220V) transformer.

TRANSFORMER AUXILARIES: For proper functioning of the transformer it is provided with several auxiliaries sub systems. Basically they are:



COOLING SUB SYSTEM: Considering the substantial amount of load delivered by a power transformer a proper cooling system has to be in place in order to prevent any hazards. Mostly, OFAF(Oil Forced Air Forced) or ONAF(Oil Natural Air Forced) schemes are used. There are radiators and fans as well. For OF type cooling butterfly valve is kept to pump oil.



CONSERVETOR: Since the oil plays a major role in the cooling of a transformer hence it has to be maintained. The conservator preserves the oil of the transformer while expansion



of oil.

BUCHHOLZ RELAY: It is a protective device used only in oil immersed transformer. It provides protection against two types of fault, incipient fault and severe fault . Under incipient fault it gives an alarm and under severe fault it trips the transformer from the line by using two floats which acts as a switch. It is universally use for transformer having rating more than 750 KVA.



BREATHER: The breather basically absorbed any moisture that may be caused due to vaporization of the oil in transformer. It contains silica gel, which changes colour


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from blue to off-white as it absorbs moisture. Thus it provides an indicator mechanism for the quality of the oil. 

PROTECTION MECHANISMS: There are temperature sensors, which can alarm if the temperature rises beyond a certain limit. Also the water supply gets activated in case of hazards like fire.

There are also kept RTD(resistance temperature detector) and PRV(pressure relief valve) for safety.

SWITCHYARD

It is a switching station ,which has the following credits:

• Main link between generating plant and transmission system, which has a large influence on the security of the supply. • Step-up and/or step-down the voltage levels depending upon the Network node. • Switching ON/OFF reactive power control devices, which have effect on quality of power.

In MTPS has mainly two switchyards. one is 220KV and another one is 400KV. These two switchyards are of three bus system(also called, one and half bus system). 1. Main bus I 2. Main bus II 3. Transfer bus


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Single Line Diagram of 220kv switchyard


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Single Line Diagram Of 400kv Switchyard EQUIPMENTS COMMONLY FOUND IN SWITCHYARD:1. Circuit Breakers 2. Current Transformer 3. Potential Transformer 4. Capacitor Voltage Transformer 5. Isolator 6. Earth Switch 7. Lightning Arrester 8. Wave traps 9. Bus bar & Clamp fittings


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1. CIRCUIT BREAKERS:It is an on-load switch which can break the circuit under any fault condition which can damage other instrument in the station. It works automatically and also manually. There are mainly two types CB are used. These are a). SF₆ gas CB, b). Vacuum Circuit Breaker. In the 220KV switchyard we have SF₆ CBs (single break) and in the 33kv switchyard we have VCB. In the 400kv switchyard we have double break SF₆ CB. This type of CB arrangement consist of i) gradient capacitor, ii) break, iii) pre-insert resistor. The gas is put inside the circuit breaker by force under high pressure. When if the gas gets decreases there is a motor connected to the circuit breaker. The motor starts operating if the gas went lower than 20.8 bar. There is a meter connected to the breaker so that it can be manually seen if the gas goes low. The circuit breakers use the SF ₆ gas to reduce the torque produce in it due to any fault in the line. The circuit breaker has a direct link with the instruments in the station, when any fault occur alarm bell rings. In a single break type only the bus bar end is isolated but in a double break type, both bus bar(source) and cable (load) ends are broken. CIRCUIT BREAKER

(Double Break)

(Single Break)


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2. CURRENT TRANSFORMER:Current transformers are basically used to take the reading of the currents entering the station. This transformer steps down the current from 1600amps to 1 amp. This is done because we have no instruments to measure such type of huge amount current. This type of transformer are used to i) protection & ii) measurement purpose. There are 5 cores used in this type of CT.

CURRENT TRANSFORMER 3.POTENTIAL TRANSFORMER:Potential transformers serve a number of functions in a power system. They are required for the operation of many types of instrumentations and relay protective systems. They are mainly used to step down the high magnitude of voltage to a save value to incorporate measuring and protection logics. They measures voltage and in conjunction with CT, they measure power. They feed synchronizing equipments. They can be used as coupling capacitor in power line carrier network.This is used in 220KV


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Switchyard.

(POTENTIAL TRANSFORMER) 4. CAPACITOR VOLTAGE TRANSFORMER(CVT):A capacitor voltage transformer (CVT) is a transformer used in power system to step down extra high voltage signals and provide low voltage signal either for measurement or to operate protective relay. In its most basic form it consist of three parts: two capacitor across which the voltage signal is split, an inductive element used to tune device to the supply frequency and a transformer to isolate and further step down voltage for instrumentation and protective relay. The device has at least four terminals, a high voltage terminal for connection of high voltage signal, a ground terminal and at least one set of secondary terminals for connecting to the instrumentation and protective relay. CVTs are typically single phase device used for measuring voltage in excess of one hundred kilovolts where the use of voltage transformer would be uneconomical. In practice the first capacitor, C1 is often replaced by a stack capacitor connected in series. This result in large voltage drop across the stack of capacitor that replaced the first capacitor and a comparatively small voltage drop across the second capacitor, C2 and here the secondary terminals.


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5.ISOLATOR:Basically an isolator is off-load switch. The use of this isolator is to protect the transformer from the other instrument in the line. The isolator isolates the extra voltage to the ground and thus any extra voltage cannot enter the line. Thus an isolator is used after the bus for protection also. Two isolator must be kept in both side of a breaker. Type of isolator used in 220KV: i)Central Rotate Double Break

(CRDB) Types of isolator used for 400KV: i) HCB(horizontal central break) ii) pantograph

HCB

Pantograph isolator


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6. EARTH SWITCH:Earth switch discharges the capacitive voltage stored in line on generator side in isolated system just after opening of CB and isolator. When earth switch is connected to the isolated but un-discharged system it discharges the stored energy to the earth, so that maintenance work can be carried out either in line or in generator side. Earth switch should be operated only when the isolators are open. In MTPS all earth switches can be operated manually.

EARTH SWITCH

7. LIGHTENING ARRESTOR:Lightening arrestors are the instruments that are used in the incoming feeders so that to prevent the high voltage entering the main station. This high voltage is very dangerous to the instruments used in the substation. Even the instruments are very costly, so to prevent any damage lightening arrestors are used. The lightening arrestors do not let the lighting to fall on the station. If some lightening occurs the arrestors pull the lightening and ground it to the earth. In any sub-station the main important is of protection which is firstly done by these lightening arrestors. The lightening arrestors are grounded to the earth so that it can pull the lightening to the ground. The lightening arrestors work with an angle of 30 to 45 making a cone. In 400kv switchyard gap-less arrestor are used & gap less material is ZnO₂.


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LIGHTENING ARRESTOR

WAVE TRAP

8. Wave Traps:Wave trap is nothing but a L-R circuit which can trap the high frequency communication signals sent on the line from the remote substation and diverting them to the telecom/tele protection panel in the substation control room (through coupling capacitor and LMU).This is relevant in Power Line carrier Communication(PLCC) systems for communication among various substation without dependence on the telecom company network. The signals are primarily tele protection signals and in addition , voice and data communication signals through same power line. The wave trap offers high impedance to the high frequency communication signals thus obstructs the flow of these signals in to the substation busbars. If there were not to be there, then signal loss is more and communication will be ineffective/probably impossible. The total systems occurs by using modulation/demodulation factors through transmitter and receiver.

9.Bus bar & Clamp fittings:The bus is a line in which the incoming feeders come into and get into the instruments for further step up or step down. There may be double line in the bus so that if any fault occurs, other can works. Thus the supply will not stop. In MTPS there have two switchyards with three bus. i)Main bus-1 & ii)Main bus –2 –Buses are main source of power in power system grid the generators or the alternator are connected in parallel to the main bus 1 or 2 to supply the power in the grid.


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iii)Transfer bus—Usually there is no power at the time of normal operation in a transfer bus of a generating station. When there is a fault in certain line so power cannot be transferred to a main bus. So transfer bus is used to transfer the power from one main bus to other main bus. In MTPS 220KV switchyard has 31no.of Bay.Among them six for GT,twelve for Line,five for SST,two for 80MVA Transformer,four for Bus coupler,two for Bus tie and 400KV switchyard has 10 no. of bay. Among them four line bay, two for GT, two for ST, one for bus-tie and another one is bus coupler. Mainly bus coupler is used to maintain the supply under fault conditions of a breaker.

10.INSULATORS:The overhead line conductors are bare and not covered with any insulating materials. The line conductors are therefore, secured to the supporting structures by means of insulating fixtures, called insulators, in order that there is no current leakage to the earth through the supports. Insulators are mounted on the crossarms and the line conductors are attached to the insulator so as to provide the conductors proper insulation and also provide necessary clearance between conductors and metal works. The insulators must provide proper insulation and necessary clearance against the highest voltage in worst atmospheric conditions to which the line is likely to be subjected. The insulator also prevent short circuiting between the different phase conductors and provide necessary mechanical support for the line conductors. Thus the insulators undoubtly one of the most important and vulnerable links in transmission and distribution of overhead transmission and distribution. In MTPS switchyards mainly disc type, string type, pin type insulators are used.


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RATINGS

SF6 CIRCUIT BREAKER(Single Break) Rated voltage Rated Impulse withstand voltage

:245KV :1050 KV

Rated power frequency voltage

:460 KVp

Rated frequency

:50 Hz

Rated normal current

:2000 A

Rated short time current

:40 KA

Rated short-circuit duration

:1 s

First pole to clear factor

:1.3

Symmetrical Breaking capacity – equivalent

:40 KA :19000 MVA

Asymmetrical

:46.4KA

Rated making current

:100 KAp

Rated pressure of hydraulic operated mechanism gauge

:250-350 bar

Rated pressure of SF₆ at 20C(gauge) Weight of complete breaker

:6.5 bar :4051kg

Weight of SF₆ gas Rated trip coil voltage Rated closing coil voltage

:25 kg :220V(DC) : 220V(DC)

SF₆ CIRCUIT BREAKER(Double Break)

Rated voltage

:420 KV

Rated Impulse withstand voltage Rated power frequency voltage

:1050/1425 KVp :520/610 KV

Rated frequency

:50 Hz

Rated normal current

:3150 A

Rated short time current

:40 KA

Rated short-circuit duration

:1 s

First pole to clear factor

:1.3

Symmetrical Breaking capacity – equivalent

:40 KA :29000 MVA

Asymmetrical

:52.5 KA


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Rated making current

:100 KAp

Rated pressure of hydraulic operated mechanism gauge

:313 ± 3 bar

Rated pressure of SF₆ at 20C(gauge)

:7.5 bar

Weight of complete breaker

:9181 kg :57.5 kg

Weight of SF₆ gas Rated trip coil voltage

:220+ 20 -10 Volt DC

Rated closing coil voltage

: 220+ 20 -10 Volt DC

CENTRAL ROTATE DOUBLE BREAK ISOLATOR Make

:H.L.M.Industries

Type Volt(kv)

:CRDB :245

BIL(kv)

:1250

STC(kA/sec)

:40

Curent(Amp)

:1250

Type of Drive

:Motor

Motor Voltage(AC)(V)

:415

Control Ckt. Voltage(D.C)(V)

:230

HORIZONTAL CENTRAL BREAK ISOLATOR Type

:HCB

Volt( KV)

:420

BIL (KV)

:1425

Switching Impulse(KV)

:1050/1245

Pᶠ (KV)

:610

STC(KA/sec)

:40

Weight of isolator(kg)

:1950 approx

Frequency(Hz)

:50

Current(A)

:2000

Type of drive

:Motor

Motor voltage(AC)(V)

:415

Control voltage(DC)(V)

:220

Weight of drive(kg)

:100

PANTOGRAPH TYPE ISOLATOR Type

:Pantograph

Volt( KV)

:420

BIL (KV)

:1425


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Switching Impulse(KV)

:1050/1245

Pᶠ (KV)

:610

STC(KA/sec)

:40


:1950 approx

Frequency(Hz) Current(A)

:50 :2000

Type of drive

:Motor


:415


:220

Weight of drive(kg)

:100

EARTHING SWITCH Type

:Telescopic

Volt( KV)

:420

BIL (KV)

:1425

STC(KA/sec)

:40


:78/pole

Frequency(Hz)

:50

Current(A)

:2000

Type of drive

:Motor


:415


:220

Weight of drive(kg)

:100

 PROTECTION

OF SWITHYARD:-

The main protections are given to line & bus-bars under different faults are 1.Distance protection:- In this type, the relay operates when the ratio of the voltage & current changes beyond a specified limit. 2.Over current protection:- All buses have a specific limit to flow the current, if current is more beyond this limit, then the o/c relay will operate. 3.Over voltage protection:- Same as o/c protection ,all buses have a specific limit to withstand a maximum voltage, if this voltage is over, then the over voltage relay will operate. 4.Earthfault protection:- Earth fault protection is one of the main protection of the lines. If there occur any earth fault, the earth fault relay will operate. http://slidepdf.com/reader/full/report-on-mejia-thermal-power-plantdvc

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5.Directional protection :- Sometimes after occurring the earth fault in line in radial system, then the direction of the current may change. Then the directional relay will operate. STATION GROUNDING SYSTEM: Power station grounding system shall be designed a) to obtain effectively low neutral to ground resistance for limiting the system over voltage and aid the operation of the protective relays in the event of ground faults and b) to limit dangerous potential gradients along the surface during short circuit currents for ensuring safety of operating personnel. Normally separate ground grids buried below the earth at a depth of 0.5 mts are constructed for the power house and the switchyard. These two grids are interconnected at several points, The grid consists of 20 mm dia. MS rod arranged in mesh form and welded at the inter section points. To improve the conductivity between the earth and the grid vertical spikes are inserted deep into the earth and welded to these horizontal rods. Earth pits are also constructed when required. Vertical risers are taken from the ground grid for connection to the ground bus above the surface. In a grounded system the neutral point of a transformer or that of a generator is connected to this bus through resistance or grounding transformer or directly as the case may be. All, the non current carrying metallic portions of electrical equipments (such as the enclosure, cable box etc) , steel structures , towers, pole etc are to be connected to this ground bus.

MOTORS: Definition: Electric motors are electromagnetic energy converters whose function is based on the force exerted between electrical currents and magnetic fields—which are usually electrically excited as well. It basically converts electrical energy into mechanical energy.

Various types of motors: DC motors: shunt series and compound AC motors: single phase, three phase synchronous motors, induction motors. 





Voltage: HT motor, LT motor, Control(servo) motor.


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According to the types of excitation motors are divided into two types:

Singly excited:  AC induction motor: An induction motor is an alternating current motor in which 

the primary winding of the stator is connected to the power source and a secondary winding or a squirrel cage secondary winding of the rotor carries the induced current. There is no physical electrical connection to the secondary winding, in its current is induced.

Doubly excited:  Synchronous motor: It has a conventional three phase stator. Its rotor winding is 

DC excited and its speed is dependent on the number of pairs of stator poles. True synchronous motor is not self starting, squirrel cage motor or wound rotor motor are required to accelerate to near synchronous speed. When operating at synchronous speed the power factor of the motor can be changed by varying the degree of excitation.

Types of AC motors: Squirrel cage induction motor: 3 ph. Winding in stator, copper bars in rotor. Wound rotor:3 ph. Winding in stator, 3 ph. Winding in rotor(shorted internally).  



Wound rotor with slip ring: 3 ph. Winding in stator, 3 ph. Winding in rotor(terminated to slip rings).



Synchronous motor: 3 ph. Winding in stator, DC winding in rotor(terminated to slip rings)

According to voltage level:There are also two types of AC motors, called HT motors and LT motors.

HT MOTORS: In the unit U#5 and U#6 ,the motor whose operating voltage is 6.6KV is under below. HT motor(W/V/Amps) BFP:

4.6MW/6.6KV/469A

ID Fan:

1825KW/6.6KV/202A

FD Fan:

825KW/6.6KV/91A

PA Fan:

1275KW/6.6KV/133.5A

Coal Mill:

2400KW/6.6KV/264A

BCW(Boiler circulating Pump): CEP(Condense Extraction Pump):

55KW/6.6KV/98.5A 325KW/6.6KV/36A


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Compressor Motor:

250KW/6.6KV/28A

Circulation Water Pump:

1920KW/6.6KV/215A

In this power plant ,the motor whose operating voltage is 11kv and 3.3kv , known as HT motors. HT motors(W/KV/Amps): MD BFP

:10 MW/11KV/605A

ID Fan

:3400KW/11 KV/2*522A (Synchronous Motor)

FD Fan

:1037KW/11 KV/70.4A

PA Fan

:2925KW/11KV/176A

Coal Mill

:525KW/3.3KV/126.5A

BCW(Boiler circulating water pump) :350KW/3.3 KV/89.1A CEP(Condensate extraction p/p) :900 KW/3.3 KV/191A Compressor Motor

:315 KW/3.3 KV

LT MOTORS: In this power plant there are so many motors which operates at 415 V for different purpose, these motors are called LT motors.

Classification of induction motors: 

Squirrel cage induction motors: This entire winding is made up of heavy copper

bars connected together at each end by a metal ring made of copper and brass. No insulation is required between the core and the bars. This is because of very low voltage generated in the rotor bars.



Slip ring or wound motors: There rotor resistance can be increased by inserting an external resistance through the slip rings.

Performance terms:  Efficiency:

η =P ουt /

P in.= 1 – (P loss/P in)

 Motor loading: Actual operating load to the motor/ Rated capacity of the motor  Power factor: Cos Φ = (KW/KVA)

Motor losses:  Core loss 

Stator and rotor resistance losses

 Friction and windage losses


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 Stray load losses

Various insulation: Class of insulation:

Max allowable temp(C):

Y

90

A

E

105 120

B

130

F

H

155 180

Reasons for the failure of motors:  Bad manufacturing quality  Continuous over loading  Frequent starts in short duration  Incorrect setting / calibration of  Improper maintenance  Failure of 

protection

interlocks

DC SYSTEM:

There are always kept a DC system to operate the auxiliary system under emergency condition such as start up , tripping of the TG , failure of AC. In MTPS phase-II two battery banks are present, one for Internal power house, another for switchyard control. In switchyard control room there is a battery room and an AC DB room. 220 volt DC for controlling the protection system and 48 volt DC for PLCC system. There also a back up battery bank is kept. Batteries are connected in series. For checking the healthiness of the battery specific gravity measurement is done periodically by hydrometer. In AC DB room Float and Float cum Boost charger are kept. Capacity of a battery : 645 Ah(220V DC) 250Ah(48V DC) Total battery : 110(220V DC) 24(48V DC) YHP-13 for 220v DC. No. of negative plate(7)= No. of positive plate(6)+1. YKP-21 for 48v DC.


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DIESEL GENERATOR: In the Black Out Condition when there is no power in Generating Station from Turbo Generator and also not from grid,in this condition to supply the emergency equipment,like scanner fan,BFP,ID Fan,Seal Oil Pump,Elevation System through emergency board, we need this Diesel Generator.In every unit there is one DG set and in case of unit U#7 and U#8 there is Two DG set to supply the emergency equipment of that corresponding unit.The capacity of DG Set at unit U#5 and U#6 is 750KVA.


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CONCLUSION Generation of quality power at a low cost being the prerogative of a thermal power plant, DVC MTPS aims at using best technologies through experienced hands to generate profitable outcomes while scoring points on environmental safety. Also, transmission of power while keeping safety of grid as well as power plant at sight is a massive duty that comes at hand in the whole process of distribution of power. These are done with utmost care in DVC, MTPS using various components as described in the previous write-ups.


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REPORT ON MEJIA THERMAL POWER PLANT(DVC)

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