thermal power station report

7/23/2019 Thermal Power Station Report

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Thermal Power Station phase-II

THERMAL POWER STATION

Very Brief Account of Visit to Thermal Power Station

ENGR. SYED MUHAMMAD MUNAVVAR HUSSAIN

Engr. Syed Muhammad Munavvar Hussain 1


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Thermal power stationA thermal power station is a power plant in which the prime mover is steam driven.

Water is heated, turns into steam and spins a steam turbine which either drives an electrical

generatoror does some other work, like ship propulsion. After it passes through the turbine, the

steam is condensed in a condenser and recycled to where it was heated; this is known as a

Rankine cycle. The greatest variation in the design of thermal power stations is due to thedifferent fuel sources. Some prefer to use the term energy center because such facilities convert

forms ofheatenergy into electrical energy.

T.P.S. Muzaffar Garh:

Installed Capacity

This Power Station is a vital and major thermal power generating installation connected

with National grid system in Pakistan. This Power Station was constructed in different Phases

having total capacity of 1370 MW. It consists of:

Three Russian units of 210 MW each

Two Chinese units of 200 MW each

One Chinese unit of 320 MW

Fuel

Dual fuel combustion provision (Gas & Furnace Oil) has been made for all the machines.Furnace oil is transported through Railway Wagons and tank Lorries.

Unit NoInstalled

Capacity

Rated

Capacity

MakeCommg.

Date

Fuel Type

ST-1 210 MW 200 MW USSR Sep. 1993 P. Gas, F. Oil

ST-2 210 MW 200 MW USSR Mar. 1994 P. Gas, F. Oil

ST-3 210 MW 200 MW USSR Feb. 1995 P. Gas, F. Oil

ST-4 320 MW 300 MW China Dec. 1996 P. Gas, F. Oil



Total 1370MW 1300MW

Table 1.1 brief views of TPS units

http://en.wikipedia.org/wiki/Power_planthttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Ship#Propulsion_systemshttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Power_planthttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Ship#Propulsion_systemshttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energy


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Amid sand dunes of area known as Rakh Khanpur, at a distance of 6 km. from

Muzaffargarh City, is located Thermal Power Complex. A few years back nobody perceived that

such a desert would yield green trees, more than 1,500 families would be residing here and aPower Station will turn into a huge Power Complex. Now, with the day and night efforts of

foreign as well as Pakistani engineers, technicians and workers, the complex has grown to the

realities with three sky-high chimneys, being highest concrete structure in Pakistan and visiblefrom the bridge of River Chenab, which is flowing to the east of the site at distance of 8 kms. In

September, 1987 contract of supply and erection of a 3x210 MW capacity Thermal Power

Station was signed with M/s. TECHNOPROMEXPORT of ex-USSR, Moscow, and 1,134 acresof government land was acquired.

Initially, about 230 acres land for the Power Station and 164 acres for residential colony

was leveled and subsequently construction was started. Later on contracts with Chinese firm,

M/s. CMEC, were signed for three units in two stages - Two Units each of 210 MW and one unitof 320 MW. In this way a power complex emerged which is going to be the biggest of all

Thermal Stations in Pakistan with the possibility of construction of two more units. Presently, the

total generation capability of three phases is envisaged as 1,370 MW.

Phase - 1 (Units 1, 2 & 3):

This phase consists of three steam units each capable of generating 210 MW electricity.The supplier started delivery of equipment to site in January, 1989, and after pre-assembly of

equipment at Site, erection started in July, 1990. Unit No. 1 was commissioned in September,

1993 and Unit No. 2 in March, 1994.

Main Building:

It contains the turbine hall having a span of 45 meters and dearator bay, 12 meters wide.

The steam turbines which drive generators are of three stages condensing type arrangedtransversely to the axis of turbine hall. The operational platform is at elevation 12.6 meters and a

maintenance bay at ground floor near Unit No. 1. The power plant is designed on the block

principle: boiler-turbine-generator-unit transformer. The fuel gas exhaust section of two units isconnected with a 200 meter high stack, outer section of which is a 195-meter high concrete shell.

Combined Auxiliary Building:

The building is connected with the main building and it houses water treatment plant to

produce 100 t/h demineralized water for the replenishment of station losses, hydrogen plant to

provide hydrogen for cooling of generators rotors, maintenance shops, laboratories and central

control room.

Fuel & Oil Facilities:

Fuel oil facilities are constructed for decanting, oil storage, preparation and supply of fuelto boiler nozzles. It also includes HSD storage as well as oil facilities for reception, storage,

purification and centralized delivery of turbine oil and insulating oil to power plant.

Hydraulic Structures:

The cooling water used in condensers is re-circulated in closed cycle with inducted draft

cooling towers. The water is being cooled for each unit in two cooling towers each consisting of

eight fans. Two cooling towers carry 27,500 Cu m/h circulating water for condensers of one unit.



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Startup Boiler:

One startup boiler using diesel oil as fuel with steam output of 50 t/h is provided to meet

steam requirement for initial start of unit as well as a backup of power plant auxiliaries. Aseparate stack of 30-meter high has been constructed for it.

Electrical Part:The electricity generated at 15.75 KV is brought out from Unit transformer at 220 KV

and fed to the National Grid via a switchyard. Power Plant auxiliaries are fed at 6.6 KV.

Phase-II (Units 5 & 6):

It consists of two units of 210 MW each having equipment similar to Phase-I. Turbines

are placed longitudinally in main building. Outdoor boilers exhaust of two units is connected to

one stack

Overview:

There are many different types of power plants including thermal power plants and hydel

power plants. Thermal power plants use fuel such as Gas, HSD, Furnace Oil or nuclear fuel toproduce heat energy that is converted to electrical energy through a series of intermediate

processes. Hydel power plants convert the potential energy of water to electrical power as itflows from higher to lower elevations.

The "traditional" thermal power plant is the Rankine cycle plant, named after the man who

invented the cycle. A power plant cycle is a series of processes in which a fluid, generally

water/steam, is used to convert heat energy to mechanical energy. The Rankine cycle in itssimplest form consists of a boiler, a turbine, a condenser, and a boiler feed pump. Early plants

had thermal efficiencies of approximately 25% to 30%. Only 25% to 30% of the heat energy in

the fuel burned in these plants was converted to electrical energy. The rest was lost in variousways.

The Rankine cycle has been refined considerably over the years and made more efficient

by the addition of components like Economizer, Feed water heaters, Super heaters and Re-heaters. The efficiency of the Rankine cycle has also been improved by increasing the pressure

and temperature of the cycle. The laws of thermodynamics and considerations such as material

limitations have prevented any significant improvement since then. Power plants commonly useheat rate to measure efficiency.

Engr. Syed Muhammad Munavvar Hussain

Fuel Energy Boiler Heat Energy

TurbineMechanical

Energy

GeneratorElectrical

Energy

4


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BoilerThe boiler is the main part of any thermal power plant. It converts the fuel energy into

steam energy. The fuel may be furnace oil, diesel oil, natural gas or coal. The boilers may be

fired from the multiple fuels.

The type of boiler used in the TPS phase-II is water tube type.

Water Tube Boilers:

In watertube boilers, boiler water passes through the tubes while the exhaust gases remain

in the shell side, passing over the tube surfaces. Since tubes can typically withstand higherinternal pressure than the large chamber shell in a firetube, watertube boilers are used where high

steam pressures (as high as 3,000 psi) are required.

Watertube boilers are also capable of high efficiencies and can generate saturated orsuperheated steam. The ability of watertube boilers to generate superheated steam makes these

boilers particularly attractive in applications that require dry, high-pressure, high-energy steam,

including steam turbine power generation.

Parameter of Boiler:Rated evaporating amount 680 t/h

Reheat steam amount 575.8 t/hMain steam pressure 140 kg/cm2 g

Temperature 541 C

Outlet pressure of Reheat System 23.8 kg/cm2 gOutlet Temperature of Reheat System 541 C

Inlet pressure of Reheat System 25.8 kg/cm2 g

Inlet Temperature of Reheat System 310 CFeed water Temperature 251 C

Boiler Efficiency (burn oil) 90.26 %

Boiler Efficiency (burn gas) 85 %Exit gas Temperature (burn oil) 153 CExit gas Temperature (burn gas) 136 C

Consumption of crude oil 48.2 t/h

Consumption of natural gas 59650 Nm 2 /h

Main Parts of Boiler:

The boilers consist of the following main parts:

Forced Draft Fan (FDF)

Air Preheater (RAH)

Burners

Furnace

Up Rise Tubes

Down Comer Tubes

Water Tubes

Super Heaters

Gas Recirculation Fan (GRCF)

Re-Heater

Induced Draft Fan (IDF)



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Chimney

Boiler Drum

Economizer

Forced Draft Fan (FDF):

The forced draft fan (FDF) sucks the air from the atmosphere which is used in the furnacefor burning. The air from the atmosphere is passed through the filter to remove the dust and other

particles from the air. The air from the FDF is then feeded to the regenerative air heaters.

The motor of the FDF has following specification;

Type KK 800 11- 8

Rated Voltage 6.6KVRated Current 114 /121.3A

Rated Speed 747rpm

Output 1000KWConnection of Stator /Rotor Y

Insulation Class FPermissible Rise 80K

Ambient Temperature 40C No. Of Phase 3

Rated Frequency 50Hz

Power Factor 0.81Degree Of Protection IP54

Moment Of Inertia 310Kg.m2

Weight 12020K/13250Kg

Induced Draft Fan (IDF):

ID fan sucks the flue gases from boiler and exhaust through chimney.

The motor of the IDF has following specification;

Type YKK 800 11- 6

Rated Power 2000kwRated Voltage 6.6KV

Rated Current 20 A

Rated Speed 991rpmConnection of Stator Winding 2Y

Insulation Class F

Permissible Rise 80k

Ambient Temperature 40C No. Of Phase 3


Degree of Protection IP54Moment Of Inertia 410Kg.m2

Weight 15970Kg



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Gas Recirculation Fan (GRCF):

The motor of the GRCF has following specification;

Type KK 400 11- 4Rated Power 315KW

Rated Voltage 6600V

Rated Current 34 ARated Speed 1491rpm

Connection of Stator Winding Y

Insulation Class FPermissible Rise 70k

Ambient Temperature 50C

No. Of Phase 3

Rated Frequency 50HzDegree of Protection IP54

Moment Of Inertia 11.7Kg.m2

Weight 3200Kg

Cooling Towers:

Cooling towers are heat removal devices used to transfer process waste heat to theatmosphere. Cooling towers may either use the evaporation of water to remove process heat and

cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the

working fluid to near the dry-bulb air temperature. Common applications include cooling the

circulating water used in oil refineries,chemical plants,power stations.

Cooling Water Pump:

The motor of the CWP has following specification;Type Y1600-16/2150

Out Put Power 1600KW

Stator Voltage 6.6KVSpeed 372rpm

Frequency 50Hz

Stator Rated Current 182AStator Connection 2Y

Ambient Temperature 50C

Insulation Class B

Weight 17500Kg

CW Pump:

Type is single stage double suction centrifugal pumpType 1400S25-1

Capacity 16000m3/H

Speed 370rpmPower 1600KW

Weight 35000kg

Head 25m

NP SHR 8.5m

http://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Oil_refinerieshttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Power_stationhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Oil_refinerieshttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Power_station


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Air Preheater:

An air preheater or air heater is a general term to describe any device designed to heat air

before another process (for example, combustion in a boiler) with the primary objective ofincreasing the thermal efficiency of the process. They may be used alone or to replace a

recuperative heat system or to replace a steam coil.

The purpose of the air preheater is to recover the heat from the boiler flue gas whichincreases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas. As a

consequence, the flue gases are also sent to the flue gas stack (or chimney) at a lower

temperature, allowing simplified design of the ducting and the flue gas stack. It also allowscontrol over the temperature of gases leaving the stack.

Economizers:

Flue gases from large boilers are typically 450 - 650F. Stack Economizers recover someof this heat for pre-heating water. The water is most often used for boiler make-up water or some

other need that coincides with boiler operation. Stack Economizers should be considered as an

efficiency measure when large amounts of make-up water are used (i.e. not all condensate is

returned to the boiler or large amounts of live steam are used in the process so there is nocondensate to return) or there is a simultaneous need for large quantities of hot water for some

other use. The savings potential is based on the existing stack temperature, the volume of make-up water needed, and the hours of operation. Economizers are available in a wide range of sizes,

from small coil-like units to very large waste heat recovery boilers.

The savings potential is a function of how much heat can be recovered, which is a

function of how much cold water needs to be heated. A generally accepted "rule of thumb" isthat about 5% of boiler input capacity can be recovered with a properly sized economizer. A

higher percentage can be recovered with a Flue Gas Condenser, assuming there is enough cold

water to condense all of the flue gas that is available. Therefore, for 'ball parking' purposes, startby comparing boiler input capacity with the need to heat water.

An economizer that recovers 5% of boiler input should easily have a 2 year payback in a

year-round application.

Boiler Protection:

Fuel protection

Gas pressure protection

Diesel oil protection

Furnace oil protection

FD fan trip

ID fan trip

Regenerative air pre heater trip Drum level high

Drum low level

Reheat steam pressure drop

Furnace pressure low

Furnace flame out

Natural gas pressure high

http://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Recuperatorhttp://en.wikipedia.org/wiki/Flue_gashttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Chimneyhttp://en.wikipedia.org/wiki/Ducthttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Recuperatorhttp://en.wikipedia.org/wiki/Flue_gashttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Chimneyhttp://en.wikipedia.org/wiki/Duct


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Steam Cycle:


Boiler Drum HP Cylinder Re- Heater IP Cylinder

Condenser

Condensate

Pump

Ejector

LP Cylinder

Economizer

HP Heaters

Feed Water

Pumps

Feed WaterTank

De-aerator LP Heaters

STEAM CYCLE

CirculatingWater

9


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Steam Turbine

Turbine is used to convert the heat energy into mechanical energy. Turbine used in tps

Muzaffar Garh is impulse-reaction steam turbine.The load requirement is controlled by the steam flow through a governing valve.

Maximum steam flow at full load is 670 tons/hour. When the load at the generator is suddenly

decreased then the rpm (frequency) of the generator is increased and to decrease the frequencywe lower down the steam flow which decreases the speed and maintains the frequency.

If load is suddenly increased rotor speed becomes slower, to increase the speed, steam flow is

increased.

Steam turbine has three parts.

1. HP turbine

2. IP turbine

3. LP turbine.

HP (High Pressure) Turbine:

First of all steam from boiler comes into the HP turbine. Steam in the HP turbine is called

live steam or main steam. Rotor blades diameter of this part of turbine is smallest of the other

parts of the turbine.

Inlet steam temperature of the HP turbine is 540 C and pressure is 130 kg/cm2.

Outlet steam temperature of the HP turbine is 290 C and pressure is 15 kg/cm2.

HP turbine has total of 12 stages including one is governing stage.

IP (Intermediate Pressure) Turbine:Steam comes into the IP turbine from HP turbine via reheaters. The steam pressure in this

section of the turbine is 14 kg/cm2 and temperature is 540 C. This part has total of 10 pressure

stages. .

LP (Low Pressure) Turbine:

The outgoing steam of the IP turbine entered into the LP turbine. Steam from the LP turbine

goes into the condenser.

Specification of the steam turbine:

Maximum load 210 MWLive steam pressure 132 kg/cm-2

Live steam temperature 538 C

Rated speed 3000 rpmHP cycle Exhaust steam temperature 310 C

HP cycle Exhaust steam pressure 24 kg/cm2

Reheat steam temperature 538 CReheat steam pressure 14 kg/cm2



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Turbine Protection:

Lube oil pressure (low and high)

Vacuum drop

Live steam temperature drop

Axial shift displacement

Gas cooling pump tripping

HP heater level high

All FW pump trip high vibration tipping

Trip unit by switch/emergency



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Furnace Safeguard Supervisory System (FSSS)

The FSSS station consists of the following parts; De-kending area

Fuel oil tanks

First Lift pump

Main Heaters

Second Lift pump

Diesel pumps

Recirculation pumps

Recirculation heaters

Filters

control Room

De-kending Area:

The furnace oil that is used as a fuel in the burners of the boiler furnace to produce the

steam is transported to the TPS through two ways;

Oil Tankers

trainFor unloading of the fuel from oil tankers and train there is separate unloading or

dekending station for each. The unloaded fuel oil is initially stored in the underground reservoir;

from there it is filled in the main storage tanks.02 pumps are used to fill the main storage tanks from the oil tankers de-kending area.

One of them is active (on load) and other is standby.

Fuel Oil Tanks:

From the de-kending area the furnace oil is filled in the storage tanks. From there it is

supplied to the burners of the boiler furnace after proper heating.Usually one storage tank is called service tank, from there furnace oil is supplied to the

units. The furnace oil is filled in the other tanks first and then filled in the service tanks through

recirculation pumps (RCP). The oil in the tanks is kept heated at the temperature 75 C to 80 C.

There are total 06 storage tanks for furnace oil each having a volume of 20,000 cubicmeters hence each can store 2, 00,00,000 liters.

There are 2 diesel oil storage tanks each having capacity of 1000 ton.

First Lift Pump:

First lift pump takes the furnace oil from the service tank and supplied to the main

heaters. There are total 04 first lift pumps which are operated according to the unit loadconditions.

The specification of fist lift pump motor is as under;

3 phase 50 Hz Induction Motor

Connection: Star



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Power: 55KW

Power factor: 0.9

Efficiency: 90%Voltage 230/400V

Speed 2950rpm

Current 177/102A

Main Heaters:

There are 04 main heaters each is connected to the respective first lift pump. The mainheaters heat the furnace oil through the steam which comes from the boiler. Steam is use to heat

the oil in the recirculation heaters.

The seam flows through the pipes which heats the oil outside the tube. The temperature

and pressure of the steam in the main heaters isTemp 270 C

Pressure 11 to 13 kg/cm2

Second Lift Pump:Second lift pumps take the furnace oil from the main heaters and supplied to boilers of

the units. There are total 04 second lift pumps which are operated according to the unit loadconditions. The temperature of the oil that is supplied to the boiler is 105 C to 120 C.

The specification of second lift pump motor is as under;

3 phase 50 Hz Induction Motor

Power: 250KWVoltage 6.6kV

Speed 2950rpm

Current 252A

Fuel Oil Cycle:



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The GeneratorThe generator is a device which converts the mechanical energy into electrical energy.

Working Principle:

The working principle of generator is based on the Faradays law of electromagnetic

induction, which states thatThe emf is always produced in the conductor which is placed in the magnetic field when

there is a relative motion between conductor and the magnetic field.

If the output electrical energy is AC, it is called AC generator or alternator. If the output

electrical energy is DC, it is called DC generator. In fact there is no difference between alternatorand DC generator except the way the output is obtained from the generator. In alternator the AC

supply is produced in the armature and supply is obtained through slip rings where as in the DC

generator the generated AC supply is obtained from the armature through split rings orcommutator which converts the AC into DC.

The following three things are necessary for the generation of electrical energy;

Magnetic field

Conductor

Relative motion between conductor and Magnetic field


Furnace Oil

TanksOil Heaters

Burners(Boiler Furnace)

Flue Gases

ID Fan

Air

Pre Heater

Exhaust

(Chimney)

FUEL OIL CYCLE

Gate & Quick

Closing

Valves

14


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In the small generator the magnetic field is being produced in the stator and the emf is

produced in the rotor through Faradays law of electromagnetic induction. The electromagnetic

are used in the generator to produce the magnetic field.In the large generator the magnetic field is produced by the electromagnetic in the rotor

and the emf is produced in the stator. The output is taken from the stator because if the output is

taken from the rotor, the rotor must have high insulation due to the high voltage induction and itmust have heavy insulation which may increase the size of the rotor, and require more power for

the prime mover to rotate this heavy rotor.

Synchronous Generator:

The generators used in the TPS are synchronous generator.

Synchronous generators are by definition synchronous, meaning that the electrical

frequency produced is locked in or synchronized with the mechanical rate of rotation of thegenerator.

A DC current is applied to the rotor winding, which then produces a rotor magnetic field.

The rotor is then turned by a prime mover (e.g. Steam, water etc.) producing a rotating magnetic

field. This rotating magnetic field induces a 3-phase set of voltages within the stator windings ofthe generator.

Field windings applies to the windings that produce the main magnetic field in amachine, and armature windings applies to the windings where the main voltage is induced.

For synchronous machines, the field windings are on the rotor, so the terms rotor windings and

field windings are used interchangeably.

Generally a synchronous generator must have at least 2 components:

a) Rotor Windings or Field Windings

Salient Pole

Non Salient Poleb) Stator Windings or Armature WindingsThe rotor of a synchronous generator is a large electromagnet and the magnetic poles on

the rotor can either be salient or non salient construction. Non-salient pole rotors are normally

used for rotors with 2 or 4 poles rotor, while salient pole rotors are used for 4 or more polesrotor.



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A dc current must be supplied to the field circuit on the rotor. Since the rotor is rotating, a

special arrangement is required to get the dc power to its field windings. The common ways are:

Supply the dc power from an external dc source to the rotor by means of slip rings and

brushes.

Supply the dc power from a special dc power source mounted directly on the shaft of the

synchronous generator.

Slip rings are metal rings completely encircling the shaft of a machine but insulated fromit. One end of the dc rotor winding is tied to each of the 2 slip rings on the shaft of the

synchronous machine, and a stationary brush rides on each slip ring.A brush is a block of graphite like carbon compound that conducts electricity freely but has

very low friction; hence it doesnt wear down the slip ring. If the positive end of a dc voltage

source is connected to one brush and the negative end is connected to the other, then the same dcvoltage will be applied to the field winding at all times regardless of the angular position or

speed of the rotor.

Some problems with slip rings and brushes:

They increase the amount of maintenance required on the machine, since the brushes

must be checked for wear regularly. Brush voltage drop can be the cause of significant power losses on machines with larger

field currents.

Small synchronous machines use slip rings and brushes.Larger machines brushless exciters are used to supply the dc field current.

A brushless exciter is a small ac generator with its field circuit mounted on the stator and its

armature circuit mounted on the rotor shaft. The 3-phase output of the exciter generator is



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rectified to direct current by a 3-phase rectifier circuit also mounted on the shaft of the generator,

and is then fed to the main dc field circuit. By controlling the small dc field current of the exciter

generator (located on the stator), we can adjust the field current on the main machine without sliprings and brushes. Since no mechanical contacts occur between the rotor and stator, a brushless

exciter requires less maintenance.

The Speed of Rotation of a Synchronous Generator:

Synchronous generators are by definition synchronous, meaning that the electrical frequencyproduced is locked in or synchronized with the mechanical rate of rotation of the generator. A

synchronous generators rotor consists of an electromagnet to which direct current is supplied.The rotors magnetic field point in the direction the rotor is turned. Hence, the rate of rotation of

the magnetic field in the machine is related to the stator electrical frequency by:

Excitation of Generator:

Excitation of synchronous generator is done via DC supply which is given to the field

winding of the generator to produce the magnetic field.The generator can be classified, with respect to the excitation, as under;

Separately Excited Generator:

The generator in which the DC supply is given to the field winding of the generator

through the external source is called separately excited generator.

Self Excited Generator:



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The generator in which the DC supply is given to the field winding of the generator

through its own generated supply is called self excited generator.

Synchronous Generator in TPS:

The main generators used in the TPS phase-I are separately excited generators. For this

purpose another synchronous generator is installed on the same shaft of the turbine and maingenerator which is called Exciter.

The exciter is a self excited synchronous generator. In the initial startup the DC supply is

given to the field winding (rotor) of the exciter by the DC batteries for 4 seconds. After that theDC batteries are cut off and the DC supply is given to the field of the exciter by its own

generated supply after the rectification.

The AC supply generated by the exciter is also given to the field winding (rotor) for its

excitation after the rectification. The AC produced by the exciter is sent to the rectifier roomwhere it is converted to the controlled DC supply by thyristers. The firing angles of the thyristers

are controlled by the AVR (automatic voltage regulator) and hence the excitation of the

generator is controlled.

Exciter generator:

Excitor generator of the excitor provides independent power supply(3-phase, 50 Hz) tothe excitation system. The exciter generator is installed on the same shaft with the turbo

generator.

The exciter is excited by two water cooling thyristor converters. The thyrister converters

are connected in parallel and operate in turn: one is in operation while other is in automaticstand-by duty. The ac and dc circuits of the thyristers includes several knife switches for removal

either of the converters from service for repair.

Initial excitation of the exciter generator is carried out by a short term connection of thestorage batteries through a contactor and rectification bridge.

Main Generator Parameters

Pilot Exciter:

Type Tfy-46-500

Rated Voltage 93/161V

Rated Current 286/165A

Rated Speed 3000rpmRated Power Factor 0.875

Phase 3

Rated Frequency 500HzArmature Connection /Y

Specification OEA.513.039

Mfg. Date 1993-3-1Rated Capacity 46KVA

Alternating Excitor:



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Type Tl-1165-4

Rated Voltage 431V

Rated Current 1562ARated Speed 3000rpm

Rated Power Factor 0.91

Phase 3Rated Frequency 100Hz

Armature Connection Y

Specification OEA.513.039Mfg. Date 1993-8-24

Rated Capacity 1165KVA

Turbine Generator Water Hydrogen Cooled

Type QFSN-210-2

Rated Capacity 246MVARated Output 210MW

Rated Voltage 15.75KVRated Current 9056A

Rated Speed 3000rpm


Phase 3Connection Of Stator Winding 2-Y

Insulation Class F

Power Factor 0.85Excitation Voltage 289V

Excitation Current 18.67A

Max.Inlet Water Temp. For Stator Winding 50CMax.Inlet Cooling Hydrogen 50C

Water Flow For Stator Winding 35m2/h

Rate H2 Pressure 0.3MPaSpecification OEA.512.137

Mfg. Date 1993-2

Cooling System of Turbo Generator:

The first question arises here is that why we need cooling of the generator?

As the current flow in the stator and rotor of the generator is very high so it increases thetemperature of the stator and rotor winding. As a result the resistance of the stator and rotor

windings increases which increase the power losses and may cause the insulation breakdown.

Two types of cooling is used in the turbo generator of TPS phase-II1. Stator cooling

2. Rotor cooling

Stator cooling:



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The stator of the turbo generator is cooled by the distillated or demineralized (demi)

water. For this purpose a special plant is installed which prepares the demi water for the stator

cooling. This demi water is also used for the cooling system of the thyrister converters. Thewater is passed though the hollow conductors of the stator winding for its cooling.

The demi water is necessary for the cooling of the stator winding because raw water is

not a pure insulator which may cause the flow of leakage current when passed through statorwinding.

The demineralized water plant removes the impurities and minerals of the raw water and

make it good insulator whose Resistivity is taken at a minimum level of 200 k.cm.The demi water that passes through the stator winding absorbs the heat of the stator

winding making it cool and becomes hot itself. The demi water then passes through heat

exchangers (coolers) where its temperature is decreased by the circulating water coming from the

cooling towers. This demi water is also passed through the mechanical and magnetic filtersbefore passing through stator winding and thyrister converters. The stator and thyristers cooling

circle is shown in figure below;

Water parameters in Heat Exchangers

Rated temp.of cold water at inlet 32 CMin: temp of cold water 15 C

No. of gas heat exchangers 02

Rated water flow in on heat exchangers 150 m3/h

Rotor Cooling:

The rotor cooling is done by the Hydrogen gas.

Hydrogen gas is used for the following purposes:1. Its heat exchange capability is much better than other gases

2. It is very lighter than other gases so do not overload the rotor.

3. Its preparation is very easy and cheap.

Hydrogen gas is filled in the generator and maintained at a pressure of 4kg/cm2. It takes

all the heat of the rotor and cools the rotor winding and gets warmed itself. For the cooling of thegas there are four gas coolers inside the generator on each corner. Circulating water of the

cooling tower is used in the gas cooler for the hydrogen cooling.

Hydrogen gas is explosive if it is combined with oxygen under pressure so to avoid any

leakage of gas and entrance of air inside the generator the rotor assembly is sealed by the seal oilwhose pressure is at least 0.7kg/cm2 more than hydrogen gas inside the generator.

When the generator is turned off for a long time for maintenance purpose hydrogen is

released from the generator in the air using special method. Method involves that firstly fill thegenerator with CO2 which release the hydrogen in the air and then in the end air is filled in the

generator and CO2 is released in the air. This method is adopted because if hydrogen is released

using air instead of CO2 then it can cause explosion due to oxygen in the air which will meethydrogen under pressure in the generator.

After maintenance hydrogen gas is refilled in the generator using the reverse process as

described above.



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Water parameters in gas cooler

Rated temp.of cold water at inlet 32 C

Min: temp:of cold water 15 CMax: water pressure 3 kg/cm2

No. of gas coolers 04

Rated water flow in on gas cooler 76.5 m3

/h

Protections of Generator:The following protection are installed for the protection of the generator in TPS phase-I;

1. Longitudinal differential current protection

This system is intended to protect against multi phase short circuit in generator stator

winding and at its leads including against double earth fault, one of which being in the generator.

2. Lateral differential current protection

This system is intended to protect against turn-to-turn short circuit of one phase in thegenerator stator winding.

3. Earth fault protection of stator winding

This system is intended to reveal and disconnect one phase earth fault of generator stator

winding.

4. Differential protection of the unit

This system is intended to backup longitudinal differential protection of generator.

5. Negative sequence current protection

This system is intended to prevent damage of generator incase of overloading by negative

sequence current caused by asymmetric load or external asymmetric short circuit and abnormaloperating condition of power grid.

6. Over current protection against overloading of generator

This system is intended for signaling at symmetric overloading of generator stator.

7. External symmetrical short circuit protection

This system is intended to protect the generator against external symmetric short circuit.

8. Protection against asynchronous mode, when excitation loss

This system is intended to protect against asynchronous mode. One of the elements ofresistance block relay for protection of the unit against external symmetrical short circuit is

used.

9. Protection of generator rotor against overloading

This system is intended to protect against overloading under emergency condition as well

as incase of failure of generator excitation system which cause long term flow of current ofabnormal value along the rotor winding.



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10. Earth fault protection in one point of excitation circuit

This system is intended to protect the generator incase of earth fault at one point ofexcitation circuit.

11. Protection against voltage increase at generator at idle operationThis system is intended to prevent inadmissible increase in voltage at turbo generator and

transformer of unit during idle operation of the unit incase of failure of excitation system.

12. Zero sequence current protection

This system is intended to backup protection operating at one phase short circuit in the

220KV network. It is also used to backup unit protections when short circuit at the 220KV side

of the unit.

13. Differential protection of the exciter

This system is intended to protect against all kind of short circuit in the exciter winding

and on its leads.

14. Over current protection of exciter against external short circuit

This system is intended to protect against over current in the external system of the

exciter.

Transformer

Generally following type of transformers are used in our power house.

Main transformer

Stand by transformer

Auxiliary transformer

Parts of Transformer:

Main transformer consists of following parts:



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1. Power fans

2. Condenser type bushing

3. Oil conservator4. Bucholz relay

5. Winding temperature controller

6. Thermostat and thermometer7. Current transformers

8. Tap changer

9. Earthing tower10. Fire protection cooling system

11. Automatic voltage regulator

Power Fans:

The natural cooling of the transformer can be increased by the addition of power fans placed at

the base or along the side of radiators, whether they are fitted directly to the tank or groups in

outside gangs.

The fans are of helical type and are of capable of generating an air flow. The motordesigned for an absorbed power .25 1 HP is closed, self cooling, with cage rotor and mounted

on bearing.Normally the fans are controlled automatically through a thermostat. In addition to make

manual operation possible as well, a preselector is often built into the system, allowing operation

by means of push buttons on the protection and control cover.

When forced cooling is provided the power fans unit is split into two units eachcontrolled through its own switch by same thermal relay.

Condenser type Bushing:

The bushing is packaged in cases, generally in the vertical position. Packing is providing to

protect the bushing from blows and moisture during transients. Moreover, the part of each

bushing normally immersed in oil is protected from moisture by a cup shaped metal or plasticcovering directly fitted to the bushing flange.

On spare bushing, not used for transformer testing, a water proof film may be found for

some construction type on the surface of resin paper. Before using the bushing, this film shouldbe removed with a blunt tool, for not to damage the surface underneath.

The bushing should be stored in dry place, always in the vertical position, even for short

period.

Atmoseal Type air-cell oil conservator:

For air cell conservator the contact between oil and outside air is prevented. Moreover the

pressure on the oil surface remains constant and equal to the atmosphere pressure. Whentransformer is running, it requires a very small maintenance limited to routine inspection.

In conservator an oil resistant, flexible, rubber oil-cell is arranged in communication with the

outside through a drier that prevents condensation in the cell. The air cell gets bigger or smallerso as to compensate oil volume variations and to keep pressure an oil surface at the atmospheric

valve. The working condition of the Buchholz relays, installed on the tank to conservator pipe, is

not out all affected by the air cell.



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Buchholz type gas accumulation relay:

This relay is provided for transformer protection when electrical breakdown occurs between the

live parts, or in the event of fault to ground, short circuits between turns, phase interruptions,burning of core, oil leakage in the tank or in the oil cooling system.

This relay will operate on the occurrence of gas formation or on sudden variations of oil level

resulting from abnormal transformer conditions by actuating an alarm signal and if the fault isserious or persistent, by putting the transformer out of service. The Buchholz relay is installed

directly on the oil pipe connecting the tank to the conservator and is normally flooded with oil, in

which its inner armature is permanently immersed with the actuating device.The upper contact for signaling purpose is closed by operation of pertaining float, when due to

an inflow of gas to the relay or the other reason, the oil level contained in the upper part of the

relay is lowered. The lower contact which controls the tripping circuit is operated by the

corresponding float when the oil level reaches the lower part of the relay.Whenever the Buchholz relay operates the alarm and the tripping circuit, it is necessary to open

the gas drawing cock and to make sure that gas is released.

Winding temperature controllerA thermal image device is used to detect the Hot Spot temperature in the winding of a power

transformer. A coil is immersed in the hottest oil layer of the transformer, transmits through thecapillary tube, the temperature variation to the temperature indicator. A heater coil is placed

around the thermometer bulb and is supplied by the secondary of main current transformer. The

current in the heater is proportional to that is flowing in the winding. The heater is designed to

obtain a temperature rise and a thermal inertia equal to those of transformer winding.It should be noted that the temperature values read on the indicator are Hot Spot values, i.e.

maximum local winding temperature. Therefore, when the transformer operates at full load, the

reading may exceed the temperature limit by the standards for the average winding temperature.

Temperature indicator:

The indicator is sealed in the tank; it is a potentiometer for remote indication and is mounted atmans height at the tank of the transformer. The thermometer bulb located in the probe, is

connected through the capillary tube to the actuating bellows of the instruments. A second

capillary tube runs parallel to the preceding one and is connected to the compensating bellows tocancel the influence of the ambient temperature. The system is filled with a special stable and

non corrosive liquid.

The instrument dial is graduated from 0 to 150 C over an arc of 270. The index 7 is actuated

through a sector gear, the latter is also operates the lever , moving the slider of potentiometer ifrequired and the lever which controls the fixed differential switch and the variable differential

switch. The device is fitted with a maximum index that can be reset to zero. The switches and the

potentiometer are connected to terminal boards and the potentiometer has fine and zeroadjustments.

Thermostat and thermometerThis device is used for the temperature control and consists of a bulb at the top part of the

transformer tank and connected through the capillary tube to a dial indicator. Besides indicating

the temperature, this instrument closed a circuit connected to an alarm device and subsequently a

second circuit directly connected to the main breaker and capable to cause the detachment of the



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transformer from the line. The measurement system can be of liquid thermometer type. The scale

is not linear but approximately logarithmic expandable with the temperature

Main Transformer:

The specification of main transformer is;

Type SFP7-250000/235TA

Phase 3Frequency 50HZ

Rated Power 250000KVA

Rated Voltage 235 3/5*2.5% /15.75 KVA

Type Of Cooling OFAFInsulation Class A

Connection Symbol YN.D1

Current 0.25%

No-load Noise Level 90dbImpedance Voltage 13.9%

No Load Losses 170.2 KWLoad Losses 675.9KW

Temp. Rise 60K

WEIGHTActive Part 158t

Oil 55.6t

Bell Tank 17.9tTotal 261.83t

Stand By Transformer:

Type SFP7-250000/235TA

Phase 3

Frequency 50HzRated Power 2500/25000/8400KVA

Rated Voltage 230 8*1.25% /6.9 /3.984KVA

Type of Cooling OFAFInstallation Outdoor

Connection Symbol YN yno d1

Noise Level 90db

No Load Current 0.33%



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No-load Losses 34KW

Load Losses 113.8KW

Temp. Rise 60K

WEIGHT

Active Part 35.1tOil 34.54t

Bell Tank 10t

Total 98.64tQuantity Of Cooler 4

Spare Cooler 1

Temperature Classification A

NOTE:

This transformer can be operated with out coolers for 20 minutes.

Auxiliary Transformer:

Type S27-2500/15TAPhase 3

Frequency 50HZ

Rated Power 25000KVA

Rated Voltage 15.75 7*2% /6.9 KVARated Current 916.4/2092A

Type Of Cooling ONAN

Insulation Class AConnection Symbol D.yn11

Noise Level 69db

Impedance Voltage 12.2% No Load Current 0.336%

No-load Losses 22.5 KW

Load Losses 109.4 KW

Limit for Temperature Rise:

Winding 60KTop Oil 50K

Insulation Level LI150AC55/LI60AC25

WEIGHT

Active Part 27500kg

Oil 19500kgTotal 58580kg

Transformer Protections:



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Differential current protection of unit t/f

Gas protection of unit transformer

Gas protection of on-load tap changer section

Remote protection at 6kv side

Current different of working and standby power supply 6kv section

Over current protection against over-loading of 6kv winding Arc protection at 6kv side/winding

MT Buchholz

MT cooling fan stop

Relief value

SWITCH YARD

Mainly there are different but most important things for the protection, measurement, meteringand for the other purposes

Circuit Breaker

Isolator

Insulator

Insulator strings

Bus Bar



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Current transformer (C.T.)

Potential transformer (P.T.)

Conductor

Control Switch

Relays

Power Line communication box

Circuit Breaker:

This is the basic and the most important part of the switchyard. Isolators are used for its

protection because the minimum cost of the circuit breaker which has been installed in KAPCO

is of 10 million rupees. So, we are required to provide protection to it to avoid the burning andthe familiar of the breaker.

Objective:

This is installed to protect or making some disconnection or connection part, So that there can be

a bridge between the two parts.This is an automatic device which opens and closes by sensing the characteristics defined

by the designer. Suppose if we want to work on the transmission line going to any other region,then we make open the connections of the circuit breaker.

On the other hand, if any fault occurs on any side of the breaker, then current transformer which

is certainly installed with a breaker senses the abnormal current and sends information to thecentral control room and also performs some action to protect the system from any accident.

Any of the line is no longer in contact with the generator, all lines are coming out from the bus

bar and there is a circuit breaker in between the line and the bus bar. So, by chance, if occurs afault in transmission line then we can easily recover it by opening the breaker. Similarly the line

from the step-up transformer to the bus bar is also protected by a circuit breaker.

So, this circuit breaker is a kind of connection and disconnection between the generator, bus barand the transmission line. So, by this way, the transmission line or substation or bus bar itself andalso generator are protected from any kind of small or big accidents.

The Necessary Capabilities of Breaker:

1. It should be capable of extinguishing the arc without undue delay.

2. It should withstand the transient voltage that appears across the contacts immediately

after the current flow ceases. So it should provide sufficient dielectric strength immediatelyafter the rupture of current.

Components of the circuit breaker:

Auxiliary switch

This is only for the purpose of the taking information about the working of the C.B. e.g. it

consists of PLCs which take information that whether the breaker is open or close. Theinformation about the opening and the closing of the breaker is taken by such a way that there are



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some normally open and normally closed contacts in auxiliary switch. So, if the breaker is closed

then information from the normally closed contacts is sent to C.C.R. (Central Control Room) and

a light is made ON there showing that Breaker is in closed condition. Similarly is the breaker isopen, then Normally open contacts are closed and in the similar fashion described above, light is

made ON in C.C.R. showing that breaker is in open condition.

Mechanical switching:

This process is done with help of the oil pressure. A certain oil pressure is obtained and then

according to the information supplied by the manufacturer, opening and closing of the breaker isdone at some pressure defined, i.e. if pressure goes less than 273 bars than breaker is opened and

then does not close itself until it is done manually.

Inside protection:

As because of the opening and closing of contacts by some other reasons, arcs are produced

inside the breaker which is dangerous for the life and the characteristics of the breaker. So, these

arcs must be quenched.

There are many methods for quenching these arcs, e.g. Air quenching

Gas quenching

Vacuum quenching

Now days, most commonly used methods for quenching the arch is the use of the SF 6 gas which

is very much efficient for doing this task.

Types of Circuit Breakers:

They can be classified with respect to two criteria

1. arc quenching media

2. constructionWith respect to arc quenching media , we have most used types listed below

The oil circuit breakers

The air circuit breakers

The SF6 circuit breakers

The vacuum type

Oil Type:

In the oil type circuit breaker, the arc is produced in the oil thus oil decomposes and replacedby the surrounding oil thus provides both cooling and give proper dielectric strength. Such an

arrangement can work for breaking duty not exceeding 150MVA.Addition can be done to increase the rating by providing pressure pot and externally generated

pressure to extinguish the arc by pushing it and also by dividing it into sections by means of

insulators .By these means, a rating of 7500MVA at 132 kV is possible. Also low oil content

breaker can be used to decrease the size and increase the life and performance of oil.



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Air Type:

Axial, radial or cross blast is used in these breakers to extinguish arc and also insulators can be

added to increase the dielectric strength.

Vacuum Type:

In this type, the vacuum is created at the contact position. When the contacts open, theresistance becomes very high since no ionization in the medium occurs. only source of electrons

is the harmonic emission through the surfaces. So no chance of re-striking arc after it is once

extinguished.

Current transformers:

Current transformers are used in power transformers as a source of energy for operation

of relays, to measure the equipment of a thermal image plant, a line drop compensator andprotection system etc.

The current transformers normally incorporated in power transformers may be of

bushing type with primary winding.

The primary is formed by connection which goes from the winding of each individualphase of the transformer to the corresponding insulator and which crosses the transformer

centrally. If the transformer ratio is very low and the accuracy is high, it is advisable to use thetype with the primary winding. As far as possible, these current transformers are arranged on

the machine in an easily accessible position.

Chemical section

The chemical section consists of the following sections;

Hydrogen plant

Demineralization plant

Oil testing lab

Water testing lab

Hydrogen Plant:



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Generation of

HYDROGEN

Alkaline

SolutionElectrolyzer

Dryer Gas Scrubber(Gas Washer)

Separating

Columns

AirCompressor

Rotor(Generator)

StorageTanks

DC PowerSupply

(330A)

Purifier


Hydrogen plant prepares the hydrogen gas which is used for the cooling of the rotor of

the turbo generator. The hydrogen gas is used for the cooling of the rotor of the turbo generator

because it has better heat transfer characteristics, cheap and easy preparation and also it is verylight and hence do not over load the rotor.

The hydrogen is prepared by electrolyses of the water. For this DC supply is given to the

electrolyzer. This Dc supply is produced after step down of the 6.6 kV supply to 400 V and thenby 3-pahe rectifier.

Raw water is used for the preparation of the hydrogen as it supports fast electrolyses

action then de-mineralized water.Potassium Hydro oxide (KOH) is used as a catalyst. The oxygen and hydrogen are

prepared in the ratio of 1:2.

A generalized layout of the hydrogen plant is shown in the figure below;

DC Power Supply:

The 3-phase 6.6 kV supply is stepped down to 400 V through step down transformers.For this purpose 02 transformers are installed in the section which has a specification as follow;

Rated Power: 96 kVARated Voltage: 415 V

Rated Current: 133.6 A



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Each transformer follows a 3-phase thyrister rectifier converting the 3-phase AC into DC

supply which is given to the electrolyzers. The thyrister converters can provide the 60 V, 1250 A

DC supply to the electrolyzers. .

Electrolyzer:

The process of electrolyses of the water takes place in the electrolyses.

The process in which DC current is passed through the water resulting the separation of

the cation and anion is known as electrolyses.The electrolyzer has 25 cells each takes 2.2 V, a total of 55 V DC and a maximum current

of 1000 A. The separated hydrogen and oxygen then leaves the electrolyzer on its own ways.

Separating Column:

The hydrogen leaving the perforated flash box (PFB) enters the separating column which

removes the small parts of alkali from it

Gas Scrubber:Gas scrubber is also called gas washer. It removes the impurities from the hydrogen such

as dust particles etc.

Dryer:

The dryer dry the hydrogen coming out from the gas scrubber. As gas scrubber do the

washing of the hydrogen gas so it has to be dried.

Receiver Tanks:

The receiver tanks store the prepared hydrogen gas. For this purpose 06 receiver tanks areused. The pressure inside the tanks is kept 10kg/cm2.

03 tanks are for oxygen and 03 are for carbon dioxide storage.

Demineralization plant

The water which is free of all the impurities, minerals, gases like Oxygen Nitrogen and

consists of only pure water (H2O) is called demineralized water.Demineralized plant is used for the preparation of demineralized water. Demineralized

water is used for the preparation of steam, for the cooling of stator of generator and for the

cooling of thyristors in the excitation system.



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The plant has total generation capacity of 90 tons/hour. Raw water is used for the

preparation of the demi water. Raw water is pumped out by the tube wells and stored in the raw

water storage tanks.Demi water is passed through the hollow conductors of stator winding for the stator

cooling. It is used for this purpose because demi water acts as an insulator & has a resistivity of

200kOhms.it does not short circuit the windings. Demi water is used for the steam preparation inthe boiler for the following reasons:

Raw water contains mineral like Calcium, Magnesium and sulphur. These minerals cause

the stacks and corrosion in the boiler tubes which causes the heat loses and may damage theboiler tubes. The designed loss of the demi water in the steam cycle is 2%. Make up demi water

is done in the hot well and feed water tank.

A generalized layout of the demi water plant is shown in the figure below;

.

_____________________________________________________________________________

_

Mech. Clarifier filters:In mechanical clarifier filter coal and gravels are is used to remove the unresolved

particles from the water.

Cation filter:

In the cation filter resins is used which replaces the Na+ & Ca2+ ions in the water from the

H+ ions. In the end water becomes acidic.


Raw Water

Mixed bed

Anion Filter

Cation filterMech.

Clarifier filter

Storage tank

Decarbonized

Exhaust

Cation 2nd

filter

Preparation of demineralized water

33


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Decarbonizer exhaust:

It removes the carbonates from the water.CO2 is removed by showering of the water

against air. It is also known as degasifier.

Anion filter:

In Anion filter castic soda (NaOH) is used which replaces the Cl-

or SO4 ions with theOH- ions forming partial demi water.

Cation 2nd filter:

It also removes the positive ions from the water.

Mixed filter:

In the mixed filter both the remaining anions and cations are removed. The water leavingthe mixed bed is the pure distilled water.

Storage tanks:

This prepared demineralized water is then stored in the storage tanks.

Water treatment:

Ammonium hydroxide, Hydrazine and Trisodium phosphate are dozed at different points

in the boiler such as boiler drum, for water treatment.

The nature of this water is acidic, to minimize the acidity of this water ammonium hydroxide

(NH4OH) is used.Hydrazine (N2H4) removes the Oxygen from water and protects the boiler tubes against

corrosion.

Trisodium phosphate (Na3PO4) is used in the boiler drum which removes the Ca, Mg and addsNa.

Oil Testing Lab:

Different tests of the furnace oil and the lubrication oil are performed in the oil testing

laboratory to check their characteristics.

The test on the transformer oil is also performed in this lab.

The following tests are performed on the furnace and lube oil:-

1. Moisture test



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2. Flash point test.

3. Viscosity test.

4. Specific gravity test.5. Acidity test.

6. Solubility test.

7. Mechanical impurity test.8. Chlorification test.

LIST OF SYMBOLS AND ABBREVATIONS

TPS Thermal power stationG/R GeneratorT/F TransformerT/R Transformer



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M.T Main TransformerA.T Auxiliary TransformerH.V.S High Voltage SideL.V.S Low Voltage SideB.B Bus Bar

A.S.B Auxiliary System BusC.B Circuit BreakerC.T Current TransformerP.T Potential TransformerR.C Relay CoilL.A Lightning arrestorTemp. TemperaturePCB Printed Circuit BoardICs Integrated Circuits

MW Mega WattMVAR Mega Volt Ampere ReactiveMVA Mega Volt AmpereEMF Electromotive force

AC Alternating currentDC Direct current

thermal power station report

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