All related with Gas Turbine Power Station working, hope you will learn from that.

3. PREFACE…
It is well evident that work experience is an indispensable part of every professional course. In the same
manner practical training in any organization is a must for each and every individual the engineering
course. The rationale behind visiting the power plant and preparing the Project Report is to study the
electrical overview, mechanical overview, various cycles and processes (viz Steam Generation, Turbo
Generation, Synchronization …etc) of the power generation and details of control and instrumentation
required in Thermal Power Plant.
We have carried out this training under well experienced and qualified engineers and technician from
various departments’ viz. Electrical, Mechanical, Chemical and Control and Instrumentation
departments. We have taken the opportunity to explore the Electrical Department, its use, necessity in
power plant and maintenance of various instruments used for monitoring and controlling the numerous
processes of power generation.
We have tried our best to cover all the aspects of the power plant and their brief detailing in this project
report. All the above mentioned topics will be presented in the following pages of this report. The main
aim to carry out this training is to familiarize ourselves with the real industrial scenario, so that we can
relate with our engineering studies.

4. Acknowledgment
Inspiration and guidance are invaluable in all aspect of life, especially when it is academic. I acknowledge
my gratitude to all those who has given me timely help me in completing my training report.
Training work is a major part of our course. It is a period in which we are introduced to the industrial
environment or in other words we can say that industrial training is provided for the familiarization with
the industrial environment, with the increased automation in the industries to increase their production.
I am highly obliged to Mr.Anwar Ali Brohi (CEO) for allowing us to join JTPS, as a trainee. I also want to
express deep sense and gratitude to Mr.Rizwan and Mr.Rehan for his personal efforts in taking me to
sites, explaining the working of power plant Turbine, Generator and its auxiliaries. his valuable guidance
during my training at JamshoroThermal Power Station.
The object of this training work is to raise the level of performance in one or more of its aspects and this
may be achieved by teaching new trends, by imbuing an individual with new attitudes, motives & other
personality characteristics.
Practical training is an important part of theoretical studies. It covers all that remains in the classroom
i.e. without it our studies remains ineffective & Incomplete. Also it explores a student to an invaluable
treasure of experience.
Also it is a well known fact that practical training plays a very important role in future building of an
individual. Only gaining theoretical knowledge is just not sufficient for sure success in life, practical
training is must & I have been given an opportunity to gain practical experience at JAMSHORO THERMAL
POWER PLANT. I avail this instance in a very satisfactory manner & think it will be very beneficial for me
in building my future.

7. Table of Contents
Table of Contents
Introduction
Basic needs and overview of a power plant
Jamshoro Thermal Power Station
Water Handling Plant
Components of Steam/Water Cycle Furnace and Boiler
PAGE NO:
2
3
5-7
7-9
9-10
Furnace and Boiler
10-12
Steam Turbine
12-14
Electrical System Overview
15-19
Automatic Voltage Regulator
20
Bibliography
21

8. INTRODUCTION
Electricity generation is the process of generating electric power from sources of energy. Electricity is
most often generated at a power station by electromechanical generators, primarily driven by heat
engines fuelled by chemical combustion or nuclear fission but also by other means such as the kinetic
energy of flowing water and wind. There are many other technologies that can be and are used to
generate electricity such as solar photovoltaic and geothermal power.
In Pakistan the abundance of gas and oil leads to establishment of thermal power stations and governing
bodies namely PEPCO, IPP’s and PAEC power acts as pioneers in the generation of electricity.
Pakistan Electric Power Company (PEPCO)
The factors responsible for the shift in policies were: generation capacity could not be increased to meet
demand; WAPDA's growth caused inefficiencies, 'demand suppression' and high tariff policy, proliferated
theft. All these factors, over the years, adversely affected WAPDA's financial condition. As part of this
program WAPDA's functions under its Water Wing and Power Wing were to be segregated. It was
previously envisaged that all power generation, hydel as well as thermal, would be corporatized. However,
later on it was decided that the hydel generation should remain part of the Water Wing or the remaining
WAPDA. PEPCO has prepared the conceptual framework and is following a comprehensive strategy
whereby WAPDA's vertical-monolithic Power Wing has been restructured into twelve (12) distinct
autonomous entities under Companies Ordinance 1984. These are: three generation, one transmission and
eight distribution corporate entities.
Vision
To make
Pakistan Power Sector customer friendly, efficient, able and responsive in meeting tee electric energy
requirements of industry, business and domestic customers, and move to an energy sufficient model from
the current energy deficient scenario, on commercially viable and sustainable basis, in order to support the
high growth economy and to meet the government's objective of "Power for All".
Thermal Generation
PEPCO's Thermal Power Generation is mainly based on generation of power from its Steam TurboGenerators, Gas Turbines (simple as well as Combined Cycle Units) installed at different Power Stations
located in Sindh, Punjab and Balochistan provinces. Indigenous Gas & Coal is the main fuel whereas
Furnace oil and HSD are also used as alternative fuel. As per Government of Pakistan policy all thermal
power generation has been restructured and four corporatized companies namely Jamshoro Power
Generation Company Limited (GENCO-1) head quarter at Jamshoro district Dadu near Hyderabad Sindh,
Central Power Generation Company Limited (GENCO-2) head quarter at Guddu district Jacobabad Sindh
and Northern Power Generation Company Limited (GENCO-3) head quarters at Muzaffargarh and Lakhra
Power Generation Company Limited (GENCO-IV) at Khanote (Sindh) have been formed and registered.
Functioning of GENCOs has commenced.

9. Basics Needs and Overview of Thermal Power Plant
SITE REQUIREMENT:- The basic requirements of thermal power plant are determined by the type, size
and other specifications of the plant. It is required to know the immediate capacity of the power plant after
construction and the extension of capacity in the future, to determine the area required for construction of
the plant. The basic things that are taken into consideration areBasic Needs and Overview of a Thermal
Power Plant. The idea that STEAM has potential energy and can be converted into kinetic energy was given
by famous scientist, Sir. James Watt. This idea became the governing principal of many mechanical
processes and finally led to the success of Thermal Power Energy. The need of establishing a Thermal Power
Plant came to engineers by the realization of the fact that Hydel Power could be utilized only for certain
period of time in a year. This section will give the basic requirements for Thermal Power Plant.
<1>Station Building, <2>Cooling Towers, <3>Switch yard compound,<4> CLIMATIC.
CONDITION:- The tropical climate is best for erection of thermal power plant, because areas having high humidity
and fluctuating temperature lead to dew point and condensation which as a result damages the electrical machines and
corrodes the insulation and over head cables. Page | 7 TRANSMISSION: -The plant area must have route available for
transmission over head cables to the nearest grid lines or load points which will be capable of accepting the generated
power output of the power station.
EFFLUENTS:-Due to heavy rate of coal combustion residual volume is also high. The main residual product is ash.
The plant must have facilities like ash pond to dispose them safely without harming the environment.
TRANSPORT:- It is one of the another vital factor of the plant as huge burden lies on transportation in daily basis
because of huge need of coal, furnace oil, hydrochloric acid and other chemical products along with mechanical
products.
WATER REQUIREMENT:- Water is required in power plant for two basic needs, first is for steam generation and
second is for cooling purpose. Thermal Power Plant requires huge volume of water, nearly of about 3 to 4 Tons/hr/MW
only for steam generation. So site of plant must also have reliable and huge water sources located near to it.
GEOLOGY:- The geology of the site should be cost effective and the subsoil must be able to with stand huge load of
foundation. Surrounding areas and approaching.
AMENITIES:-Some considerations like availability of hospital, educational institutes and other facilities must be taken
into account.
PERSONNEL REQUIREMENTS:- To run a plant smoothly requirement of skilled and unskilled personnel is very
important. So recruitment of workers and skilled personnel should be made carefully and in adequate amount.
PROXIMITY OF AIRFIELDS:- The airfields must be studied properly to avoid mishaps as the chimney height
ranges from 500 to 600 fts and boiler housing is of 200 fts in general.

10. Schematic Diagram of Thermal Power Plant

11. Jamshoro Thermal Power Station
LOCATION
Thermal Power Station Jamshoro is situated in District
Jamshoro (Sindh) 5 Km North-West of the village of
Jamshoro on Indus High-way at the right bank of River Indus
Mohra Jabal, about 18 Km from center of Hyderabad. The
Karachi is approximately 150 Km South-West of Jamshoro
connected with Super-Highway.
at
city of
Fuel (Gas / Furnace Oil) Supplies
Sui
Southern Gas Company Ltd (SSGCL) is in contract with WAPDA/JPCL to supply Gas for power generation at
TPS Jamshoro. The daily Gas allocation is 62 MMCF with minimum guaranteed Gas supply of 53 MMCF. The
Maximum requirement of Gas for three dual fired Units is about 140 MMCFD whereas average Gas
requirement is 90 MMCFD.
Furnace Oil is arranged at competitive bidding by oil marketing companies on fortnightly basis from Karachi
through tank Lorries / tank wagons.
Installed Capacity
This Power Station comprises of four units having total capacity of 850 MW. Unit No.1 250 MW Japan origin is
Furnace oil fired, whereas Units 2,3 and 4 of 200 MW China Origin each are dual fired i.e. Gas/Furnace Oil.
Unit No
Rated Capacity
Dependable Capacity
Comm: Date
Fuel Type
ST-1
250 MW
194 MW
27-01-1990
Furnace oil
ST-2
200 MW
ST-3
200 MW
130 MW
27-06-1990
Dual( Gas+F.O)
ST-4
200 MW
130 MW
21-01-1991
Dual( Gas+F.O)
Total
850 MW
454 MW
OFF
(Because of shortage of 03-12-1989
fuel)
Dual( Gas+F.O)

12. Details of TPS, Generating Units
UNIT-1 (Block I)
Project Digest (Complex-I)
Unit
No
Installed
Capacity (MW)
ST-1
250
Fuel
Furnace Oil
Commissioning Date
27.01.1990
Project Cost
(Mil. Rs.)
Contractor
Manufacturer
6,762
M/s Electric
& Co.
Japan
M/s Fuji Elect.
& Co Japan
M/s
Mitsui/Relay
Japan
Energy Generation Since Commissioning upto 30 June 2008
Unit
No
ST-1
Commissioning
Date
Hours of
Operation
27-01-1990
109625
Energy Generated (GWH)
18198
UNIT-2 (Block I)
Project Digest (Complex-I)
Unit No
Installed
Capacity (MW)
Fuel
Commissioning Date
ST-2
200
Dual (Gas/FO)
03.12.1989
Project Cost
(Mil. Rs.)
8,869
Contractor
Manufacturer
M/s CMEC
China
M/s Harbin
Turbine, Boiler
& Electrical
Machinery Co
Harbine China
Energy Generation Since Commissioning upto 30 June 2008
Unit No
Commissioning
Date
ST-2
03-12-1989
Hours of
Operation
107821
Energy Generated (GWH)
15848

13. UNIT-3 (Block II)
Project Digest (Complex-I)
Unit No
Installed
Capacity (MW)
Fuel
Commissioning Date
ST-3
200
Dual (Gas/FO)
17.08.1990
Project Cost
(Mil. Rs.)
8,869
Contractor
Manufacturer
M/s CMEC
China
M/s Harbin
Turbine, Boiler
& Electrical
Machinery Co
Harbine China
Energy Generation Since Commissioning upto 30 June 2008
Unit No
Commissioning
Date
Hours of
Operation
Energy Generated (GWH)
ST-3
27-01-1990
94640
14137
UNIT-4 (Block II)
Project Digest (Complex-I)
Unit No
Installed
Capacity (MW)
Fuel
Commissioning Date
ST-4
200
Dual (Gas/FO)
20.01.1991
Project Cost
(Mil. Rs.)
8,869
Contractor
Manufacturer
M/s CMEC
China
M/s Harbin
Turbine, Boiler
& Electrical
Machinery Co
Harbine China
Energy Generation Since Commissioning upto 30 June 2008
Unit No
Commissioning
Date
Hours of
Operation
Energy Generated (GWH)
ST-4
21-01-1991
93404
13665

14. Water Handling Plant
In Thermal power plants, plenty of water is needed for generation of electricity.
Water in a Power Plant is used
for:
1. Production of Steam- for rotating turbine.
2. Cooling Purpose- For cooling of various equipments.
Water which is used as a working fluid needs some treatment.
Reasons to choose Water as a Working Fluid:
•
It is only common substance available & exists in 3 states (Ice, water, steam)at normal temperature. • Having high
specific heat mean heat carrying capacity is high. • Having low specific volume than air. • Low Cost
• High Availability
• Non-reactive
But water is
universal solvent; it dissolves many gases, salts, metals etc. so no source of water is pure so for the formation of
stem water should e pure otherwise generated steam will damage the turbine like rusting.
Impurities in Water Impurities present in water are grouped into 4 categories:
1) Suspended Matter
• Mean any matter floating or suspended nature in water
• Microorganisms
• Grits
2) Dissolved Salts
• Ca, Mg, K, Chlorates, Sulphates, Silicates etc.
3) Dissolved Gases
 Oxygen, Carbon dioxide, Ammonia etc.
Water is recycled and used for various purposes:
Water Cycle

15. Flow Chart
COMPONENT OF STEAM/WATER CYCLE:
A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam
generating tubes and super-heater coils. Necessary safety valves are located at suitable points to avoid
excessive boiler pressure.
Condenser: The condenser condenses the steam from the exhaust
of the turbine into liquid to allow it to be pumped. If the
condenser can be made cooler, the pressure of the exhaust steam
is reduced and efficiency of the cycle increases. The surface
condenser is a shell and tube heat exchanger in which cooling
water is circulated through the tubes. The exhaust steam from the
low pressure turbine enters the shell where it is cooled and
converted to condensate (water) by flowing over the tubes as
shown in the adjacent diagram. For best efficiency, the

16. temperature in the condenser must be kept as low as practical in order to achieve the lowest possible
pressure in the condensing steam.
High Pressure Heater: A heater located downstream of boiler feed pump. Typically, the tube side design
pressure is at least 100Kg/cm2, and the steam source is the high pressure turbine. [The heating process by
means of extraction of steam is referred to as being regenerative]
Low Pressure Heater: A Heater is located between the condensate pomp and either of the boiler feed
pump. It normally extracts steam from low pressure turbine.
GSC: Gland steam condenser is meant for condensing the steam which was used for sealing the LABYRINTH
GLAND and reusing it in cycle.
Economizers: These are heat exchange devices that heat fluids, usually water, up to but not normally
beyond the boiling point of that fluid. Economizers are so named because they can make use of the
enthalpy in fluid streams that are hot, but not hot enough to be used in a boiler, thereby recovering more
useful enthalpy and improving the boilers efficiency. They are a device fitted to a boiler which saves energy
by using the exhaust gases from the boiler to preheat the feed. Typically the cooling water causes the
steam to condense at a temperature of about 35 °C (95 °F) and that creates an absolute pressure in the
condenser of about 2–7 kPa (0.59–2.1 in Hg), i.e. a vacuum of about −95 kPa (−28.1 in Hg) relative to
atmospheric pressure. The large decrease in volume that occurs when water vapours condenses to liquid
creates the low vacuum that helps pull steam through and increase the efficiency of the turbines. The
condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the
atmosphere, or once-through water from a river, lake or ocean.
Cooling Towers: The condensate (water) formed in the condenser after
condensation is initially at high temperature. This hot water is passed to cooling
towers. It is a tower- or building-like device in which atmospheric air (the heat receiver)
circulates in direct or indirect contact with warmer water (the heat source) and the
water is thereby cooled. A cooling tower may serve as the heat sink in a conventional
thermodynamic process and when it is convenient or desirable to make final heat
rejection to atmospheric air. Water, acting as the heat-transfer fluid, gives up heat to
atmospheric air, and thus cooled, is recirculate through the system, affording
economical operation of the process. With respect to drawing air through the tower,
Forced Draft Cooling Tower
there are three types of cooling towers:
a).
Natural Draft
b).Induced draft c).Forced Draft
Note: Here at JTPS Forced Draft Cooling Method is used.

17. Furnace and Boiler
What is Boiler?
A boiler is a closed vessel in which water or
fluid is heated. The heated or vaporized fluid exits the
for use in various processes or heating applications,
including boiler-based power generation, cooking, and
sanitation. Here in TPS Jamshoro, the boiler is a
rectangular furnace about 50 feet (15 m) on a side and
130feet (40 m) tall. Its walls are made of a web of high
pressure steel tubes about 2.3inches (58 mm) in
diameter.
other
boiler
Types of Boiler:
In fire tube boiler, hot gases pass through the
tubes and boiler feed water in the shell side is converted into
steam. Fire tube boilers are generally used for relatively small
steam capacities and low to medium steam pressures. As a
guideline, fire tube boilers are competitive for steam rates up to
12,000 kg/hour and pressures up to 18 kg/cm2. Fire tube boilers
are Fire tube Boiler available for operation with oil, gas or solid
fuels. For economic reasons, most fire tube boilers are
nowadays of “packaged” construction (i.e. manufacturers shop
erected) for all fuels.
Fire Tube Boiler:
Water Tube Boiler:
In water tube boiler, boiler feed water flows
through the tubes and enters the boiler drum. The circulated water is
heated by the combustion gases and converted into steam at the
space in the drum. These boilers are selected when the steam
demand as well as steam pressure requirements are high as in the
of process cum power boiler / power boilers. Most modern water
tube designs are within the capacity range 4,500 – 120,000 kg/hour of
steam, at very high-pressures. Many water tube boilers nowadays are
“packaged” construction if oil and /or gas are to be used as fuel. Solid
fired water tube designs are available but packaged designs are less
common.
Note: At TPS, Jamshoro, Water tube Boilers are incorporated.
Furnace:
A furnace is a device used for heating. The name derives from Latin
fornix, oven. The boiler furnace auxiliary equipment include soil or
gas feed nozzles and igniter guns, soot blowers, water lancing and
observation ports (in the furnace walls) for observation of the
furnace interior. Furnace explosions due to any accumulation of
combustible gases after a trip-out are avoided by flushing out such
gases from the combustion zone before igniting the fuel i.e. gas or
vapor
case
boiler
of
fuel

18. oil. The gas or oil is blown with part of the combustion air into the boiler plant through a series of burner
nozzles. Secondary and tertiary air may also be added. Combustion takes place at temperatures from
1300-1700°C. Particle residence time in the boiler is typically 2 to 5 seconds, and the particles must be
small enough for complete combustion to have taken place during this time. This system has many
advantages such as ability to fire varying quality of coal, quick responses to changes in load, use of high
pre-heat air temperatures etc. One of the most popular systems for firing pulverized coal is the
tangential firing using four burners corner to corner to create a fireball at the center of the furnace.
Boiler Drum: Boiler Drum is the part of boiler where the
dematerialized water is stored and is inserted into the boiler. 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’s then inserted into the boiler
through the water walls. Water Walls are basically tubes along
the walls of the furnace, it is here where the water is converted
into steam at1300 and water separated due to centrifugal
force. The pressure of boiler drums is150kg/sq.cm and must be
always maintained. Water in the drum comes from feed control
station via economizer.

19. Steam Turbine
The 250/210 MW turbine installed in TPS, Jamshoro is one of
condensing-tandem-compound, three cylinder, horizontal, disc,
and diaphragm, reheat type with nozzle governing and is directly
coupled with A.C generator.
ROTOR: -
The rotor is basically the main rotating part of the turbine which
also called the shaft and is attached with the rotor of the A.C
generator via coupling. Rotor is basically divided into 3 categories
and they are as follows: -
is
a) HIGH PRESSURE ROTOR: - This is
basically made of single Cr-Mo-V steel forged
with internal disc attached to T-shoot
fastening designed especially for stabilizing
the HPT and preventing the axial shift.
b) INTERMEDIATE PRESSURE ROTOR: This is made from high creep resisting CrMo-V steel forging and the shrunk fit disc are
machined from nickel-steel forging. This
basically adjusts the frequency of the blades.
c) LOW PRESSURE ROTOR: - This is made
from the above mention alloy used in IP
Rotors; blades are secured to the respective
disc by riveted fork root fastening. Wires are
provided in all stages of this to adjust the
frequently of the blades.
BLADES: -
Blades are single
most costly element fitted in the turbine. Blades fitted in the stationary part are called guide blades and those
fitted in the rotor are called moving or working blades. Blades are of basically three types, they are as follows: a) Cylindrical ( constant profile) blade
b) Tapered cylindrical blade
c) Twisted and varying profile blade
SEALING GLANDS: To eliminate the possibility of steam leakage to the atmosphere from the inlet and the exhaust end
of the cylinder, labyrinth glands of the radial clearance type are provided which provide a trouble free
frictionless sealing.
EMERGENCY STOP VALVES AND CONTROL VALVES: -
Turbine is equipped with emergency stop valves to cut off steam supply and with control valve regulate
steam supply. Emergency stop valves are provided in main stream line and control valves are provided in the hot
reheat line.
COUPLING: -

20. Since the rotor is made in small parts due to forging limitations and other technological and economic
reasons, the couplings are required between any two rotors. The coupling permits angular misalignment, transmits
axial thrust and ensures axial location.
BEARING: Journal bearing are manufactured in two halves and usually consist of bearing body faced with anti-friction
tin based habiting to decrease coefficient of friction. Bearings are usually force lubricated and have provision for
admission of jacking oil. Thrust bearing is normally Mitchell type and is usually combined with a journal bearing,
housed in spherically machined steel shell. The bearing between HP and IP rotor is of this type. The rest is of
journal type.
BARRING GEAR: The barring gear is mounted on the L.P rear bearing cover to mesh with spur gear L.P rotor rear coupling.
The primary function of the barring gear is to rotate the rotor of the turbo generator slowly and continuously during
the start-up and shut sown process when the temperature of the rotor changes.
TURBINE LUBRICATION OIL SYSTEM: The LUB-OIL system of turbine comprises of following category.
a) MAIN OIL PUMP: - It is mounted on the front bearing pedestal and coupled through gear coupling to the rotor.
When the turbine is running at its normal speed of 3000rpmthen the oil to the governing system (at 20 kg/sq.cm)
and to the lubrication system (at 1 kg/sq.cm) is supplied by this pump.
b) STARTING OIL PUMP: - It is a multi-staged centrifugal oil pump driven by A.C powered electric motor. It
provides the oil requirement for starting up and stopping of the turbine. It provides oil to the governing system and to
the lubrication system until the turbine is running at speed lower than 2800rpm.
c) STANDBY OIL PUMP: - This is a centrifugal pump driven by A.C motor. It runs for initial10 minutes at the
starting to remove air from the governing system and fill up oil to it.
d) EMERGENCY OIL PUMP: This is a centrifugal pump driven by D.C motor. This pump is foreseen as a backup oil pump to A.C oil pumps. This
pump automatically cuts in when the A.C power fails in the power station.
e) JACKING OIL PUMP: - This pump enables the complete rotor assembly to be raised upon to be floated in the
bearing assembly during the start-up and shut down process of the process. Thus this prevents the damage to the
bearings when the shaft is too low for hydrodynamic lubrication to take place. JOP sucks and delivers oil to the
journal bearings at 120kg/sq.cm for lifting of the rotor.
f) OIL COOLERS: - The oil of governing and lubrication system is cooled in the oil coolers by the circulating water.
There are five such coolers; four are for continuous operation and one for standby.

21. Electrical System Overview
ELECTRICAL STSTEM OF THERMAL POWER BASCICALLY CONSISTS OF FOLLOWING PARTS:
 GENERATORS
 SWITCHYARD
 POWER DISTRIBUTION SYSYTEM
Generator
The transformation of mechanical energy into electrical energy is carried out by
generator. The A.C generator or alternator is based on the principal of electromagnetic induction and
generally consists of a stationary part called stator and a rotating part called rotor. The stator houses the
armature windings and the rotor houses the field windings. A D.C voltage is applied to the field winding
in the rotor through slip rings, when the rotor is rotated, the lines of magnetic flux is cut through the
stator windings. This as a result produces an induced e.m.f (electromotive force) in the stator winding
which is tapped out as output.
The magnitude of this output is determined by the following equation:E = 4.44/O f N volts
Where E = e.m.f induced; O =Strength of magnetic field in Weber; f= Frequency in cycles per second or in
hertz; N = Number of turns in the winding of the stator;
Again,
f = P n/120;
Where P = Number of poles; n = revolutions per second of the rotor.
From the above expression it is clear that for the same frequency number of poles increases with
decrease in speed and vice versa. Therefore low speed hydro turbine drives generators have 14to
20poles where as for high speed steam turbine driven generators have 2 poles. Generator Components
Rotor: Rotor is the most difficult part to construct; it revolves at a speed of 3000rpm. The massive nonuniform shaft subjected to a multiplicity of differential stresses must operate in oil lubricated sleeve
bearings supported by a structure mounted on foundations all of which poses complex dynamic behavior
peculiar to them. It is also an electromagnet and to give it the necessary magnetic strength the windings
must carry a fairly high current. The rotor is a cast steel ingot and it is further forged and machined. Very
often a hole bored through the centre of the rotor axially from one end to the other for inspection. Slots
are then machined for windings and ventilation.
Rotor winding: Silver bearing copper is used for the winding with mica as insulation between
conductors. A mechanically strong insulator such as micanite is used for lining the slots. For cooling
purpose slots and holes are provided for circulation of cooling gas. The wedges the windings when the
centrifugal force developed due to high speed rotation tries to lift the windings. The two ends of the
winding are connected to slip-rings made of forged steel and mounted on insulated sleeves.

22. Stator: The major part of the stator frame is the stator core, it comprises of inner and outer frame. The
stator core is built up of a large number of punching or section of thin steel plates. The use of cold rolled
grain-oriented steel can contribute to reduction of stator core. Stator windings: Each stator conductor
must be capable of carrying the rated current without overheating. The insulation must be sufficient to
prevent leakage current flowing between the phases to earth. Windings for the stator are made up from
copper strips wound with insulated tape switch is impregnated with varnish, dried under vacuum and
hot pressed to form a solid insulation bar. In 210MW generators the windings are made up of copper
tubes through which water is circulated for cooling purpose.
Generator Cooling and Sealing System
1) HYDROGEN COOLING SYSTEM:
Hydrogen is used as cooling medium in large capacity generators in view of its high heat carrying capacity
and low density. But in view of its explosive mixture with oxygen, proper arrangement for filling, purging
and maintaining its purity inside the generator have to be made. Also in order to prevent escape of
hydrogen from the generator casing, shaft sealing system is used to provide oil sealing.
The system is capable of performing the following functions:a) Filling in and purging of hydrogen safely.
b) Maintaining the gas pressure inside the machine at the desired value all the time.
c) Provide indication of pressure, temperature and purity of hydrogen.
d) Indication of liquid level inside the generator.
2) Generator Sealing System:
Seals are employed to prevent leakage of hydrogen from the stator at the point of rotor exit. A
continuous film between the rotor collar and the seal liner is maintained by means of oil at the pressure
which is about above the casing hydrogen gas pressure. The thrust pad is held against the collar of rotor
by means of thrust oil pressure, which is regulated in relation to the hydrogen pressure and provides the
positive maintenance of the oil film thickness.
The shaft sealing system contains the following components.
a) A.C Oil Pump
b) D.C Oil Pump
c) Oil injector
d) Differential Pressure Regulator
e) Damper Tank.
Excitation System:
1).Static Excitation:
•Alternator terminal voltage is used here.
•SCR gate signal are derived from alternator output through CT and P.T.
• SCR- based controlled rectifier is supplied is supplied from alternator output through step down
transformer.
• Alternator terminal voltage is used here.
• To generate the alternator output, it is run at rated speed with its field supplied from a separate
D.C supply bank.

23. • Rectifier output voltage is fed to the alternator field winding.
• This scheme is less expensive requires little maintenance.
• Excitation energy depends on alternator speed.
2) BRUSHLESS EXCITATION:
•Main shaft of prime movers drives pilot exciter, main exciter and the main alternator.
•Main exciter supplies A.C power to silicon diode bridge rectifier through hollow shaft which feeds the
D.C to the field of main alternator.
• Pilot exciter feeds 3-phase power to main exciter.
• Pilot exciter is a permanent magnet alternator.
•This scheme is mainly employed in turbo alternators.
Specification of Generators
PARAMETERS
Maker
Rated O/P(KW)
Power Factor
KVA
Stator
Rotor
R.P.M
Frequency(Hz)
Phase
Connection
Coolant
Gas Pressure
Insulation Class
Year of Manufacture
UNIT-1
JAPAN
250000
0.85
294100
Voltage16500V
Current10750A
Voltage-290V
Current-2395A
3000
50
3
YY
H2
3.0BAR
Class-F
1985
UNIT-2
CHINA
210000
0.85
247000
Voltage15700V
Current-9056A
UNIT-3
CHINA
210000
0.85
247000
Voltage15700V
Current-9056A
UNIT-4
CHINA
210000
0.85
247000
Voltage15700V
Current-9056
Voltage-310 V
Current-2600A
3000
50
3
YY
H2 and H2O
3.5BAR
Class-F
1988
Voltage-310V
Current-2600A
3000
50
3
YY
H2 and H2O
3.5BAR
Class-F
1988
Voltage-310V
Current-2600A
3000
50
3
YY
H2 and H2O
3.5BAR
Class-F
1988

24. TRANSFORMERS

It is a static device which transfers electric powers from one circuit to the other without any change in
frequency, but with a change in voltage and corresponding current levels also.

Here the transformers used are to transfer electric power from 15.75KV to 220KV or 400KVthat are provided
to the national grid.

The step-up generator transformers are of ONAN/ANOF/AFOF cooling type.
Power Transformers
 Power Transformers enhances the productivity as well as maximizes the capacity level of the high power
supply equipments.
These are ultimate for the regular power without any cut off. They are used for control high voltage and
frequency for the different systems.
Power transformers having the following standards: They can assist three phases. There ratings are up to
2000 KVA. Copper and aluminum winding material is used in this. Applicable Standards are IS, IEC, ANSI,
JIS, etc. It is sufficient for primary as well as secondary voltage .


Auto Transformer




High voltage auto-transformers represent an important component of bulk transmission systems and are
used to transform voltage from one level to another.
These auto-transformers are critical for regional load supply, inter-regional load transfers and for certain
generator/load connections.
To minimize the impact of this type of failures, utilities may carry some spare units to guard against such
events. These spare units are going to cost utilities money (utility cost) to purchase, to store and to maintain
and utilities should try to strike the right balance between the utility cost and the risk cost (if spare units are
not there).
Major or catastrophic failures to this equipment can have severe consequences to electric utilities in terms
of increased operating costs and customer load losses.
Advantages of Autotransformers:
1.
2.
3.
4.
5.
6.
7.
Its efficiency is more when compared with the conventional one.
Its size is relatively very smaller.
Voltage regulation of autotransformer is much better.
Lower cost.
Low requirements of excitation current.
Less copper is used in its design and construction.
In conventional transformer the voltage step up or step down value is fixed while in autotransformer, we can
vary the output voltage as per out requirements and can smoothly increase or decrease its value as per our
requirement.
Applications:
1. Used in both Synchronous Motor and Induction Motor.
2. Used in electrical apparatus testing labs since the voltage can be smoothly and continuously varied.
3. They find application as boosters in AC feeders to increase the voltage levels.

25. Transformer Cooling
The load that a transformer carries without heat damage can be increased by using an adequate cooling system.
This is due to the fact that a transformers loading capacity is partly decided by its ability to dissipate heat.
1. Dry Type Cooling
2. Air Forced/Air Naturel(AF/AN) - Transformers temperature is being kept at acceptable levels by forced/naturel
air from a fan/air circulation. Cooling fins are attached to increase the surface area of heat radiation.
3. Oil Forced/Oil Naturel (OF/ON) – Oil are used in transformer to provide insulation and as a coolent agent. If the
oil is circulated by pump than it is known as Oil Forced cooling system, otherwise Oil Naturel Cooling System.
In Jamshoro TPS naturally ONAN, ONAF, OFAN, OFAF and dry cooling system are used for transformer cooling
purpose.

26. AUTOMATIC VOLTAGE REGULATOR (AVR)
It is a regulator which regulates the output voltage at a nominal constant voltage level.
Role of AVR AVR (Automatic voltage regulator) has following roles.
1) To regulate generator terminal voltage
Mainly generator under no-load condition, AVR regulates the generator voltage to voltage setter
(90R).
*AVR detects terminal voltage and compare with voltage setter (90R).
*AVR regulates field current via the Exciter.
*Generator terminal voltage is regulated by field current.
Vt < 90R _ Field current will be increase
Vt > 90R _ Field current will be decrease
2) To adjust MVars (Reactive power)
When the generator connected to power grid, AVR adjust reactive power by regulate generator
voltage.
Reactive Power (Q) =(Vt-VS)
MVar (Reactive power: Q) is regulated by generator terminal voltage. Therefore AVRcan regulate
MVars.
Vt is increased _ MVars will be increase
Vt is decreased _ MVars will be decrease
3) To Improve the Power System Stability
There are two stabilities:
-Transient Stability…….Improved by AVR
-Dynamic Stability……Improved by PSS(Power System Stabilizer)

27. Bibliography
List of Websites:
www.wikipedia.org/
www.google.com/
www.jpcl.com.pk
Books:
Elements of Electrical Power Station Design by: Professor M.V Deshpande
Power Plant Engineering By: Balleney