This is all about The Durgapur Projects Limited. This was one of the earliest thermal power plants established in free India.

1. DR. B. C. ROY ENGINEERING COLLEGE,
DURGAPUR, WEST BENGAL- 713206
A VOCATIONAL TRAINING REPORT ON FAMILIARIZATION WITH
THERMAL POWER PLANT
(Commencing from 02.07.2019 to 01.08.2019)
THE DURGAPUR PROJECTS LIMITED(DPL), DURGAPUR,
WEST BENGAL, INDIA
DEPARMENT OF ELECTRICAL ENGINEERING
SUBMMITED BY :-
SHIVENDRA BHUSHAN (12001616050)

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CONTENTS
Acknowledgement
Introduction
DPL Power Plant Review
Power Generation
Coke Oven Plant
Alternator
Cooling Tower
Transformer
Protection System
Switch Yard
Conclusion
References

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ACKNOWLEDGEMENT
The project has been prepared based on the vocational training
undergone in a highly esteemed organization of Eastern region, a
pioneer in Generation, Transmission & Distribution of power, one of
the most technically advanced & largest thermal power stations in
West Bengal, the Durgapur Projects Limited (DPL), Durgapur. We
would like to express our heartfelt gratitude to the authorities of DPL
and Dr. B. C. Roy Engineering College, Durgapur for providing us such
an opportunity to undergo training in the thermal power plant of DPL.
We would also thank its esteemed engineers for the plethora of
knowledge and the experience they have shared with us during the
training period.
we express our sense of gratitude and indebted Mr. C.S. Saha Roy
(Operation and Maintenance Dept. DPL) for their valuable guidance,
motivation, continuous encouragement and timidly help throughout the
training. We would like to give special thanks to Mr. Nandalal
Chakraborty for giving us support and encouragement.
Last but not the least we would like to thank The Almighty God
without whom this would not have been dreamt of.

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INTRODUCTION
The DURGAPUR PROJECT LIMITED (DPL) was established in 1958
by Dr. Bidhan Chandra Roy. It consist of coke oven batteries, by product
plant, and water works. It is under the administrative control of the
Government of West Bengal.
DPL is the first undertaking of the state government which has been
engaged in development of infrastructure for industries and was
given the stature of industries. It has helped in development of
various large, medium and small scale industry in and around
Durgapur.
It produces coke oven gas, supply water and electricity. DPL’s coke
oven complex is India’s largest merchant cookery producing coke of
global quality. The plant has rail and linking with Kolkata, Siliguri and
Dhanbad and sea port at an elevation 73m above sea level.
The Durgapur Projects Limited’s total power generation capacity today
stands at 660 Megawatt(MW). It is engaged in all three fundamental

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areas of a power utility- Generation, Transmission and Distribution. It
generates and distributes power in an uninterrupted mode at grid
frequency. The largest unit is of 300 MW capacity followed by one of
250 MW and one of 110 MW.
The current demand being around 300MW which is about 45% of the
total installed capacity of the utility. It meets local demand through its
captive transmission and distribution networks. As a Distribution
Licensee it caters around 56,000 consumers of different categories
spread over an area of 125 Sq. Km.
present installed capacity:-
Units Unit VI Unit VII Unit VIII Total
Capacity 110 300 250 660
 Thermal Power Station:-
 A generating station, which converts heat energy of coal
combustion into electrical energy, is known as a steam power
station.
 A steam power station works on the modified Rnkine Cycle.
Steam is produced in the boiler by utilization of heat of coal
combustion that is then expanded in the prime mover(i.e.
steam turbine) and is condensed to be fed into the boiler
again. The steam turbine drives the alternator which converts
mechanical energy of turbine into electrical energy.
RANKINE
CYCLE

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 Advantages of using Rnakine Cycle:-
 The fuel used is quite cheap and available.
 Less initial cost as compared to other generating station.
 It can be installed at any place irrespective of the existence of
coal. The coal can be transported to the sites of the plant by
rail or road.
 It required less space as compared to the hydroelectric power
station.
 Layout of a thermal power plant:-

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DPL POWER PLANT REVIEW
 INFRASTRUCTURE:-
Unit No Year of commissioning Present capacity Renovated capacity
I. 10.08.60 30MW Scrap
II. 10.06.60 30MW Scrap
III. 23.06.64 70MW Decommissioned
IV. 29.06.64 70MW Decommissioned
V. 04.07.66 77MW Decommissioned
VI. 01.01.87 110MW 110MW
VII. 01.03.08 300MW 300MW
VIII. 01.10.14 250MW 250MW
 LAND: 1910 acres comprising 1060 acres for plant 850 acres for
township.
 Water Works: Originally commissioned with a capacity of MGD
in 1960, the water works was expanded up to a capacity of 41
MSD of water treatment of DVC for use of company’s plant,
township and other industries and domestic consumers.
 SUBSTATIONS: A substation is a part of an electrical generation,
transmission and distribution system. Substations transform
voltage from high too low, or the reverse, or perform any of
several other important functions. Between the generating station
and consumer, electric power may flow through several substations
at different voltage levels. Substations may be owned and operated
by an electrical utility, or may be owned by a large industrial or
commercial customer. A substation may include transformers to
change voltage levels between high transmission voltages and
lower distribution voltages, or at the interconnection of two
different transmission voltages.

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The substations we observed during our Industrial Training at
DPL, Durgapur were: -
11kV Switching station at Water Works at DPL.
33kV Switching Station at City Centre.
132kV Switching Station at DPL.
 COKE OVEN: DPL comprises of three coke oven plants and 4.5
meter tall recovery type Cove Oven Batteries with 400mm along
with coal washery and by-products plant. Present production
capacity is 27000M.T. which can be increased to 40000 M.T with
commissioning of 3rd battery.
 RAILWAY NETWORK: Separate railway Exchange Yard
(DCOP siding) with railway maintained Weighbridge facility.

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POWER GENERATION
Steam power plant basically operates on the Rankine cycle. Coal is
burnt in a boiler, which converted water into steam. The steam is
expanded in a turbine, which produces mechanical power driving the
alternator coupled to the turbine. The steam after expansion in
turbine is usually condensed in a condenser to be fed into the boiler
again. In practice, a large number of modification and improvements
have been made so as to improve the thermal efficiency of the plant.
The working of a modern steam power plant can be divided
into four main circuit namely:
1. Fuel and Ash circuit: In DPL, coal
is delivered from the supply point to
storage site by road. Then the coal is
taken into the boiler bunker from where
it falls into the hopper by gravity and

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finally requisite quantity of coal falls into grate by directly or coal
spreader.
2. Air and fuel Gas Circuit: Air is taken
from atmosphere by forced draught fan or
induced draught fan through air pre -
heater, and flue passing to chimney and
then admitted to the furnace. Finally,
exhausted to the atmosphere through
chimney.
3. Feed Water and Steam Circuit: The steam coming out of turbine is
condensed and condensate is extracted from condenser by extraction
pump and is forced to the low
pressure feed water to raised the
temperature. The feed water is
now pumped through deaerator.
The feed water is then pumped
into boiler through the
economizer in which it is further
heated by the heat of flue gas.
4. Cooling Water Circuit: Cooling water
is supplied from river or cooling tower
through screen to remove the matter that
might choke the condenser tube. It is
circulated through the condenser for

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condensing the steam and finally discharge to the suitable position and
in maintaining in flow pressure.
 STEAM GENERATING EQUIPMENT OF POWER PLANT:
Steam power plant consist of boiler for production of steam and
other auxiliary equipment for the utilisation of fuel gas.
 BOILER:
Boiler is a major equipment of steam power plant. In a boiler, we
burn coal to produce heat energy which will make the water to
superheated steam. Here 2 type boilers are used namely- fire tube
and water tube boiler. From boiler, steam passes to super-heater,
economizer, air pre–heater and then passes through the chimney to
the atmosphere.
In DPL, there are 6 boiler tabulated as :-
Description Unit1 Unit2 Unit3 Unit4 Unit5 Unit 6
Boiler
Babcock
&
Wilcox
Babcock
&
Wilcox
Babcock
&
Wilcox
Babcock
&
Wilcox
Mitsubishi ABL
Coal
(MT/D)
504 504 1260 1260 1293 1848
BOILER FURNACE: A boiler furnace is chamber in which fuel is
burnt to liberate the heat energy and it provides support and enclosures
for burners. Its walls are made of re-factory materials is such as fire clay,
silica kaolin etc.
SUPER-HEATER: A super-heater is a device which remove the last
traces of moisture from the steam leaving the boiler tube and also
increase its temperature above the saturation temp. It provides two

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principal benefits firstly, the overall efficiency is increase, secondly, too
much condensation in the last stages is avoided .The super-heater steam
is fed to turbine through the main valve.
ECONOMISER: It is basically a heat changer by which the
temperature of feed water, coming from high pressure heater is increased
to the saturation temperature or slightly less than the saturation
temperature corresponding to the drum pressure. The feed water is fed to
economizer before supplying to the boiler. Economiser raises boiler
efficiency 10%-12%.
AIR PRE-HEATER: An air pre heater increase temperature of air
supplied for coal burning by driving heat from flue gasses. Air is drawn
from the atmosphere by a force draught fan and is passing through air
pre-heater supplying to the boiler furnace. The air pre heater extracts
heat from flue gas. The principle benefits of heating the air increased
1% boiler efficiency and increased steam capacity per sq. Meter
boiler surface.
DIFFERENT TYPES FAN FOR BOILER HOUSE: A fan can be
defined as a volumetric machine which like pump moves quantities of
air & gas from one place to another. In doing so it overcomes resistance
to flow by supplying the fluid with the energy necessary for contained
motion.
1) Forced Draught Fan: To take air from atmosphere at ambient
temperature to supply essentially all the combustion air can either be
sized to overcome all the boiler losses or put the air in furnace.
2) Induced Draught Fan: Used only in balanced draught unit to suck
the gases out of furnace & through them into the stack. Handle fly ash
laden gasses at temperature of 125-200. Speed seldom exceed 1000 rpm.
3) Primary Air Fan: Used for pulverized system usually sized for 1500
rpm due to high pressure.

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4) Seal Air Fan: Used to seal mill bearing, coal feeders, and coal pipes
in case of pressure type mill. Speed depends on the types of
arrangements off an.
5) Ignite Air Fan: Used to provide necessary combustion air to the
ignite control damper is provided on the discharge which modulates to
maintain a constant differential pressure across ignite when any ignite is
in service. Typical speed 1460 rpm.
6) Scanner Air Fan: Used to provide necessary cooling air to the flame
scanners. Typical speed 3000 rpm.

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COKE OVEN PLANT
DPL’s Coke Oven Complex is India’s one of the largest Merchant
Cookery producing Coke of global quality. The current installed
capacity of the Coke Oven Complex is 0.5 million tons of Gross Coke
per annum, 20000 tons of Crude Coal Tar per annum & million NM3 of
Coke Oven gas per annum.
The DPL plant has Rail/Highway/Road linkages to cities of Kolkata,
Siliguri, Dhanbad & Delhi & sea port at Haldia. The fuel used in this
plant is coal. Here low grade bituminous coal low grade bituminous
(calorific value – 6000 Kcal/Kg) is used. This coal is converted into
coke by undergoing different process with the help of different types of
3 phase ac motors.
 AC MOTOR:
An AC motor is an electric driven by an alternating current (AC). It
commonly consist of 2 basic parts,
 STATOR– Having coils supplied with alternating current to
produce a rotating magnetic field. The parts of stator are –
 STATOR FRAME
 STATOR CORE
 STATOR WINDING
 ROTOR – Attached to the o/p shaft i.e. given a torque by the
rotating field. In rotor has –
 ROTOR WINDING
 TYPES OF AC MOTORS:

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 Squirrel cage motor: In overall shape it is a cylinder mounted
on a shaft. Internally it contains longitudinal bars set into grooves
& connected at both ends by shorting rings forming cage like
shape.
 Slip ring motor: A wound rotor motor is a type of inductive
motor where the rotor winding are connected through slip ring to
external resistances. Adjusting the resistance allows control of
speed-torque characteristics of the motor. Wound-rotor motor
can be started with low inrush current.
 VARIOUS PARTS OF AC MOTOR:
 Body with stator winding
 End shield drive end
 Bearing washer
 Preloading washer
 Deep groove ball bearing
 Inner bearing cover
 End shield non drive
 Rotor
 Terminal box cover
 Rubber packing
 Terminal block assembly
 Terminal box
 Conduit plug
 Fan
 Circlip
 Fan cowl
 Feather key for transmission element
 Feather key for fan
 Eye bold
 Connecting link

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ALTERNATORS
A.C generators are usually called alternators. They are also called
synchronous generator. Rotating machines that rotates at a speed
fixed by the supplying frequency & the number of poles are called
synchronous machine.
 Construction:
Similar to the other rotating machine, an alternator consist of two
main parts namely, the stator & rotor. The stator is the stationary
part of the machine. It carries the armature winding in which the
voltage is generated. The output of the machine is taken from stator.
The rotor is the rotating part of the machine. The rotor produces the
main field flux.
 Stator construction:- The various part of the stator include the
frame, stator core, stator winding and stator cooling arrangement.
The frame may be of cast iron for small size machine and welded
steel type for large type machines. In order to reduce hysteresis and
eddy current losses the stator core is assembled with high grade
silicon content steel lamination.
 Rotor construction- There are two type of rotor namely salient
pole type and cylindrical pole type.
a) Salient pole rotor- The term salient pole means projection, thus
salient pole rotor consist of pole projection out of the surface of
the rotor core. It have large number of poles and operating at
lower speed.
b) Cylindrical rotor- Its rotor construction form a smooth
cylinder. It generally has two or four poles. These rotor turbines
are driven by gas or steam turbine also called turbo generator.
Its runs at high speed and its rating varies from 10MVA to
1500MVA.

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 EXCITATION SYSTEM FOR ALTERNATOR:
Excitation means production of flux by passing current in the field
winding. In these plant there are two types of system used for
excitation:
1) D.C system : Direct current is required to excite the field
winding of the rotor of the synchronous machine. D.C is
supplied to the rotor field by a dc generator called exciter.
Smaller dc generator called pilot exciter. The main and the pilot
exciter are mounted on the main shaft of the alternator.
2) A.C System : There are two types of exciter system. Rotating
system; this has a high frequency excitation system, permanent
magnet pilot exciter and uncontrolled rectifier.
 COOLING SYSTEM:
In this plant cooling was done in 1 & 2 unit by air.Thus closed circuit
air cooled generator has shaft mounted fan and horizontal water cool
air copular are mounted in the hot duct. In case of unit 3, 4 and 5
hydrogen cooling is done.
 SPECIFICATION OF ALTERNATOR:
Unit No. 1&2 Alternator
RATED VOLTAGE 1100+-7.5%
RATED CURRENT 3440A
BASE MVA 37.5 MVA
PHASE 3
SPEED 3000RPM
FREQUENCY 50HZ
POWER FACTOR 0.8
EXCITAION 205VOLT,408 Amp
CONNECTION YY
MANUFACTURED BY ENGLISH ELECTRIC

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Unit No. 3,4&5 Alternator
RATED VOLTAGE 1100+-7.5%
RATED CURRENT 4650/4600/4330/3940A
BASE MVA 88.5/87.5/82.5/75.2 MVA
PHASE 3
SPEED 3000RPM
FREQUENCY 50HZ
POWER FACTOR 0.87/0.88/0.9
EXCITAION 381/372/384/366VOLT,665/650/670/640Amp
CONNECTION YY
FOR H2 COOLING 1.05/1.05/0.5/0.65 KG/cm2
MANUFACTURED BY SIMENS
TYPE
RATING
HYGROGEN PRESSURE
APARENT OUTPUT
ACTIVE OUTPUT
RATED VOLTAGE 1100
RATED CURRENT 220
SPEED 3000RPM
FREQUENCY 50HZ
POWER FACTOR 0.8LAG
GENERATOR TERMINAL 6
CONNECTION YY
MANUFACTURED BY SIMENS

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COOLING TOWER
A cooling tower is equipment used to reduce the temperature of a water
steam by extracting heat from water and emitting it to the atmosphere.
Cooling water is pumped from the turbine condenser by the tower pump
to the cooling tower. Inside the tower the water passes through
sprinklers and sprays out in the field drops. The water then falls as
droplets passing over picking where it is made to present a greater
surface area to the cooling air. The water then falls into the cooling
tower pond. Air is drawn near the bottom of the tower, either by natural
drought or by a fan. The air passes up the tower and cools the water is it
does so. Any water droplets which have been carried up by the air
removed by the water droplets eliminator screen.
 Types of cooling Tower :
 Natural Drought Cooling Tower
 Mechanical Drought Cooling Tower
There are different classes of Mechanical Drought Cooling Tower :
 Forced Drought Cooling Tower
 Induced Drought Cooling Tower
 Balanced Drought Cooling Tower

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TRANSFORMER
There are three transformer in unit 8 of DPL. They are :
 Generating Transformer
 Unit Auxiliary Transformer
 Station Transformer
 Generating Transformer : it
is the main power
transformer employed in the
power plant. It steps the
voltage from 16.5 KV to 220
KV and delivers the power.
Stepping up the voltage
reduces the transmission to
long distances. The rating of
the transformer (MVA rating)
will be almost equal to the
alternator or generator rating.
 Unit Auxiliary Transformer : It steps down the voltage from
16.5 KV to 6.6 KV and supplies to most of the auxiliary like
condensate extraction pump, mills, deminerlised cooling water
pump etc.
 Station Transformer : it is there to power up the station common
bus operating at higher voltage (6.6 KV) and common supplies or
driver of power plant which may not depend upon unit power
generation.

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PROTECTION SYSTEM
 Transformer Protection And Accessories:
There are many protection devices used to protect a power transformer.
The factors protecting the protection scheme are its size, important and
location of transformer. The accessories and protection devices are :-
 Buchholz Relay: Buchholz relay is a safety device mounted on
some oil-filled power transformers and reactors, equipped with an
external overhead oil reservoir called a conservator. The Buchholz
Relay is used as a protective device sensitive to the effects of
dielectric failure inside the equipment.
 Conservator and Breather: A conservator is used to maintain the
oil level up too predetermined value in the transformer main tank
by placing it above the level of the top of the tank. Breather is
connected to conservator tank for the purpose of extracting
moisture as it spoils the insulating properties of the oil.
 Marshalling box: It has two meter which indicate the temperature
of the oil and winding of main tank.
 FUSE: A fuse is a short piece of wire or thin strip which melts
when excessive current through it for sufficient time.
 BUS COUPLER: The bus coupler consists of circuit breaker and
isolator.
 Circuit Breakers:
A circuit breaker is an automatically operated electrical switch designed
to protect an electrical circuit from damage caused by overload or short
circuit. Its basic function is to detect a fault condition and interrupt
current flow. There are different types of circuit breakers which are: -

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1. Air circuit breakers
Rated current up to 6,300 A and higher for generator circuit
breakers. Trip characteristics are often fully adjustable including
configurable trip thresholds and delays.
2. Vacuum circuit breakers
With rated current up to 6,300 A, and higher for generator circuit
breakers. These breakers interrupt the current by creating and
extinguishing the arc in a vacuum container.
3. Oil circuit breakers
A high-voltage circuit breaker in which the arc is drawn in oil to
dissipate the heat and extinguish the arc; the intense heat of the arc
decomposes the oil.
4. Sulfur hexafluoride (Sf6) high-voltage circuit breakers
A sulfur hexafluoride circuit breaker uses contacts surrounded by
sulfur hexafluoride gas to quench the arc. They are most often used
for transmission-level voltages and may be incorporated into
compact gas-insulated switchgear.
 PROTECTION OF SUBSTATION:
 LIGHTNING ARRESTORS: A lightning arrestor is a device
used in power systems and telecommunications systems to
protect the insulation and conductors of the system from the
damaging effects of lightning.

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SWITCHYARD
 BUS BAR:
Here mostly Aluminium pipes confirming to IS-5032 are used to arrange
the rigid bus connection. The size of conductor depends on voltage like:
1. 40 mm
2. 65 mm
3. 80 mm
4. 100 mm
The materials commonly used for bus bar and connection of strain type
are ACSR and AAAC. Bundled conductors are also used to reduce the
corona loss.
 BUS BAR ARRANGEMENT:
 Single Bus Bar arrangement
 Single Bus Bar system with sectionlisation
 Double Bus Bar arrangement
Pedestal insulator supports the Bus Bar and connection. Clearance is
constant due to rigidness of bus bar. The distance between Bus Bar and
ground in not very large for maintenance purpose. Due to large diameter
of pipes, corona loss is less.
 There are current transformer, circuit breaker, capacitive voltage
transformer, isolators, and Bus supported post insulators in theh
switchyard to charge the Main Bus 1 and Main Bus 2.
 A 220/132/33 KV autotransformer steps down the 220 KV voltage
to 132 KV.

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CONCLUSION
Now from this report we can conclude that electricity plays an important
role in our life. We are made aware of how the transmission of
electricity is done. We too came to know about the various parts of the
Substation system.
We have obtained lots of experiences from this industrial training at
DPL. We have got one month exposure in this industry. This exposure
helped in gaining practical experience what we have actually seen in
the industry. We could use the theoretical knowledge in the practical
field i.e. at DPL.
The Durgapur Projects Limited has got radio communication in
microwave range in order to transmit and receive data with various
Substations in Durgapur to get reliable transmission and distribution of
electricity.

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REFERENCES
 www.yahooanswers.com
 www.britannica.com
 www.webopedia.com
 www.encyclopedia.com
 www.encyclopediadramatica.com/