ramgarh gas thermal power plant

1. A
TRANING REPORT
ON
“RAMGARH GAS THERMAL POWER PLANT, JAISALMER”
Submitted for partial fulfilment of the requirements for the award of the
Degree of
Bachelor of Technology
In
Electrical Engineering
G Guided by: - Submitted by: -
Dept. of Electrical Engineering Krishan Kumar
(16ECTEE025)
VII Sem Electrical
j
Session 2019-20j
Department of Electrical Engineering
University College of Engineering & Technology
Bikaner, Rajasthan

2. 2
INDEX
S.NO. TITLE PAGE NO.
1. Introduction about RGTPP 6
2. Operational performance of plant 9
3. Power plant cycle 11
4. Brief introduction of plant operation 13
5. Introduction to plant equipment’s 14
1.0 GAS turbine 15
1.1 Compressor 15
1.2 Combustor 15
1.3 Transition pieces 15
1.4 Turbines 15
1.5 Exhaust 15
2.0 GAS turbine support system and their
equipment’s
15
2.1 Starting system 15
2.1.1 Diesel engine 15
2.1.2 Torque converter 15
2.1.3 Accessory gear box 15
2.1.4 Hydraulic ratchet 16

3. 3
2.1.5 Jaw clutch mechanism 16
2.2 Lubricating oil system 16
2.2.1 Oil reservoir 16
2.2.2 Lubricating pump 16
2.2.3 Heat exchanger 16
2.3 Cooling and sealing air system 17
2.4 Ventilating system 17
2.5 GAS turbine and compressor cleaning system 17
3.0 Reducing gear box 17
4.0 H.R.S.G and steam turbine equipment’s 17
4.1 H.R.S.G 17
4.2 Steam turbine 17
4.3 Condensate circuit equipment’s 19
4.3.1 Condenser 19
4.3.2 Ejectors 19
4.3.3 Extraction pumps 19
4.3.4 Gland steam condenser 19
4.4 Feed water circuit 19
4.4.1 Feed water tank 19
4.4.2 HP feed pumps 19
4.4.3 LP feed pumps 19
5.0 Common support system for GT and ST 19

4. 4
5.1 CW and ACW system 19
5.2 Air compressor 19
5.3 Raw water system 20
5.4 Laboratory 20
5.5 Fire protection system 20
5.6 Block start D.G SET 20
6. Constructional details of GAS turbine 20
7. STG: a brief introduction 22
8. D.C system 27
9. Excitation system and A.V.R 29
10. Construction details of generator and exciter 32
1.0 Stator 33
1.1 Stator frame 33
1.2 Stator core 33
1.3 Stator winding 33
1.4 Stator end covers 33
2.0 Rotor 34
2.1 Rotor shaft 34
2.2 Rotor winding and retaining ring 34
2.3 Field connections 34
3.0 Bearings 34
4.0 Generator and air cooler 34

5. 5
5.0 Excitation system 35
5.1 Pilot exciter 35
5.2 Main exciter 35
5.3 Rectifier wheel 35
11. 132KV Switch yard 35
1. Bus bars 36
2.Insulators 36
3.Isolators 37
4.Circuit breaker 38
5.Protective relays 38
6.Current transformer 39
7.Potential transformer/Voltage transformer 40
8.Lightnning arrester 40
9.Capacitive voltage transformer 41
10.Wave trap 41
11.Bus coupler 42
12. Conclusion 43

6. 6
INTRODUCTION ABOUT RAMGARH GAS THERMAL
POWER PLANT (RGTPP)
RGTPP is located near Ramgarh Town at about 60 km from district head quarter, Jaisalmer
(Rajasthan), which is largest district of the state. Its installed capacity is 220.5 MW. And this
plant is located in largest state of India, based on area.
There was problem in maintaining desired quality standards in electric supply to Jaisalmer on
account of excess losses because of longer transmission lines. To rectify above problem and to
utilize available natural gas in this area RGTPP was established in this border district whose
existing capacity is 220.5 MW.
Gas transportation system
ONGC and IOCL are engaged in exploration of oil and natural gas deposits in western
Rajasthan. Gas Authority Of India Ltd. (GAIL) laid down 12”diameter and 65 km long pipe line
for supply of gas from Gamnewala based gas collection plant to Ramgarh, which has been
further extended upto Dandewala gas field of Oil India Ltd. Total distance of Dandewala
Terminal is approximately 67 km from Ramgarh Terminal. This pipe line is being maintained by
GAIL.
GAS PERCENTAGE
NITROGEN 31.9064 %
METHANE 48.5668 %
CARBON DIOXIDE 18.8793 %
ETHAN 0.5009 %
PROPANE 0.0333 %
ISO-BUTANE 0.0285 %
N-BUTANE 0.0513 %
ISO-PENANE 0.0185 %
N-PENANE 0.0130 %
HEXANE 0.0000 %
TOTAL
100 %

7. 7
Availibility of water
Requirement of water for power plant is supplied through Sagar Mal Gopa branch of Indira
Gandhi Nahar Project. (IGNP). FOR THIS a 27 KM Long, 5.4 cusec capacity pipe line is laid
from RD-190 of Sagar Mal Gopa Branch to power plant & another pipe line from RD-200. For
ensuring proper electric supply requirements, a Sub-station of capacity 2X250KVA, 33/0.4KV,
and a pumping station has been established at RD-190 in addition to construction of a water
storage tank of capacity 77000m3
at power plant.
Electricity Transmission System:
To ensure efficient transmission of electricity generated in the power plant, a 215km long
Ramgarh-Jaisalmer-Barmer line & 165km Ramgarh-Pokaran of 132 KV has been laid.
Expected System Operation:
In spite of unfavorable geographical conditions and supply of gas of lower quality than
expectation, expected electricity is being generated in this power plant.
STAGE UNIT NO. CAPACITY
(MW)
COST
(Rs. CRORE)
SYNCHRONISING
DATE
1. GT-1 35.5 180 12.01.1996
2. GT-2 37.5 07.08.2002
3. STG 37.5 300 25.04.2003
4. GT-3 110 640 30.03.2013

8. 8
Operational Performance of Plant
Particulars 2006-07 2007-08 2008-09 2009-10 2010-11 2011-12 2012-13
Gross Generation (LU) 4041.440 4141.153 3486.78
2
3539.44 3028.85 5367.94 4979.06
Plant load Factor (%) 41.75% 42.78% 36.00% 36.57% 31.29% 55.30% 51.44%
Aux. Power
Consumption(LU)
268.179 551.61 333.116 279.029 161.452 95.796 90.245
Gas
consumption(SCM)
2404828 2488753 2097821 2136358 1834815 297151090 27301223
Looking to increasing demand of electricity fro providing drinking water in desert area and
flood lighting on INDO-PAK Border fencing, state Govt. found it essential to raise the capacity
of RGTPP. In RGTPP is three stages.
FIRST STAGE:
Bharat Heavy Electrical Ltd. (BHEL) supplied necessary equipments for this power plant, and
Rajasthan State Bridge Construction Corporation carried out building construction. This unit is
capable in electric generation using both gas and diesel. In power plant 12 underground are
constructed for storage of diesel having total capacity of 2520KLt. In this stage single unit of
35.5 MW, in this stage only gas turbine (GT-1) is used.
SECOND STAGE:
First unit of this power plant is being operated by open cycle system, resulting in higher cost on
electricity generation. Reduction in cost is only possible when first unit is operated on
Combined Cycle System. So, under expansion program of this project, work of installation of a
gas turbine and a steam turbine is taken in hand. In this system, electricity will be generated by a
steam turbine utilizing heat obtained from exhaust of gas turbines through a Heat Recovery
Boiler. Thus, no additional fuel will be required for operating Steam Turbine.
Under stage –II one gas turbine unit (GT-2) of 37.5 MW and one steam (STG) of 37.5 MW.

9. 9
THIRD STAGE:
The gas unit of 110 MW commissioned on 30.03.2013 and at present steam unit of 50 MW
under construction under stage III which is scheduled to be commissioned in May 2014.
1. Proposed capacity 160 MW
2. Location Ramgarh
3. Total plant area 796 bigha,17 biswa
4. Project cost 640 crores
5. Fuel GAS and HSD
6. Source of water Indra Gandhi canal
7. Fuel required 17 lac. SCM per day
8. Water allocation 10.8 cusecs
First unit of this power plant is being operated by open cycle system, resulting in higher cost on
electricity generation. Reduction in cost is only possible when first unit is operated on
Combined Cycle System. So, under expansion Program of this project, work of installation of a
gas turbine and a steam turbine is taken in hand. In this system, electricity will be generated by a
steam turbine utilizing heat obtained from exhaust of gas turbines through a Heat Recovery
Boiler. Thus, no additional fuel will be required for operating Steam Turbine.
Under stage-II, one Gas Turbine Unit GT-2(37.5 MW) was commissioned and synchronized
with the grid on 7.8.02. The Steam Turbine Unit STG (37.5 MW) was also commissioned
and synchronized with the grid on 25.4.03 and from 30.03.13 a new Gas turbine unit GT-
3(110 MW) is added, thus the plant has been made operational in combined cycle mode with
a total capacity of 220.5 MW.

10. 10

11. 11
POWER PLANT CYCLE
Ramgarh Gas thermal power station is Combined Cycle power station.
Open Cycle:
When Gas Turbine (GT) exhaust is diverted directly into the atmosphere due to no provision
of HRSG (Heat Recovery Steam Generator) or non availability of HRSG then its called as
GT is running in open cycle. In open cycle as gas turbine high exhaust gas is not utilized for
heat transfer in boiler so its efficiency will come down.
Combined Cycle:
When Gas Turbine exhaust is diverted to HRSG in which high temperature Gas Turbine
exhaust gas passes through HP Super Heater, HP Evaporator, HP Economizer, LP
Evaporator, LP Economizer, and Condenser Preheater (CPH) thus heat of gas turbine
exhaust gas absorbed by above series of bank located inside the HRSG and temperature of
gas turbine exhaust which is about 570 deg C will come down to 135 deg C.
By utilizing the heat of gas turbine exhaust HRSG (Boiler) generates Steam which is used to
run Steam Turbine Generator (STG).
Thus, we can generate an additional power (about 50 % of the gas turbine generation) in
Steam Turbine Generator without any extra fuel cost. Thus, we can get 30% extra efficiency
by running the gas turbine in combined cycle.
As gas turbine is operated on Brayton Cycle principle and Steam Turbine is rotated on
Rankine cycle principle that is why it is called Combined Cycle.

12. 12
Advantages of Combined Cycle Process:
1. Decreases in capital cost per mw installed.
2. High overall efficiency i.e. 48%
3. Compact in size
4. Low main power required for its operation and maintenance
5. Low water requirement
6. Pollution free atmosphere and clean works place
7. Low installation time
8. High reliability and flexibility of the plant

13. 13
BRIEF INTRODUCTION OF
PLANT OPERATION
At RGTPP gas to the turbines is being supplied through GAIL terminal from oil wells of ONGC
and OIL, which are attached to discover oil and natural gas recourses in Western Rajasthan. The
quantity of the gas is 9.5 Lac SCM per day. From GAIL Terminal gas is supplied to Gas
Booster Compressor (GBC motor) at pressure of 10-15kg/cm2
and quantity of gas is 9.5 Lac
SCM/day.
Gas Boost Compressor which is driven by 6.6kv H.T motors.
The work of the Gas Boost Compressor is to compress gas and to supply required pressure of
gas for power production to gas turbine. In compressing process by GBC the pressure of the gas
increases from 10-15kg/cm2
to 18-23kg/cm2. The output of the GBC motor is first merged and
then is divided further, before blowing into the Combustion Chamber.
There are two GBC motor in RGTPS, GT-1 and GT-2. The blowing pressure is 18-23 kg/cm2
.
Combustion Chamber is a place where ignition of fuel mixed with air occurs with the help of the
sparkplugs, the voltage on both sparkplugs is 15000 V dc. On combustion, the gas gets mixed
with air then the gas will expand, and air pressure will increases. This air exhausts on the gas
turbine buckets & nozzels and gas turbine starts to rotate. There are two generators of 35.5 MW
and 37.5 MW attached with GT-1 and GT-2 respectively, mounted on the same shaft as the
turbine. So GT-1 and GT-2 produces 35.5 and 37.5 MW electricity respectively.
The exhaust of GT is flue gases. The temperature of flue gas is near about 500 deg C. This
exhaust may also be relieved into the atmosphere with the help of controlled valves. But this
exhaust is taken in use to produce electricity. So, this power plant is called Combined Cycle
Power plant. This exhaust (flue gas) of the gas turbine is further passed into the Heat Recovery
Steam Generator (HRSG). It is a boiler. Water circulating in drum is superheated with the help
of flue gases. This superheated steam runs the Steam Turbine Generator, so it is called unfired
combined cycle.
The generator is mounted on the same shaft as of the steam turbine, produces 37.5 MW
electricity. The steam which is blowing on the gas turbine should be superheated.
Steam should be superheated so that-
1. No corrosion will be occurred,
2. Enthalpy drop will be less.
Power generation is also done at low voltage because of the insulation problem.
If the power generation is done at high voltage, then there are following disadvantages-
1. Losses will be more
2. Wire also may burn out
3. High insulation will be required which is very costly

14. 14
INTRODUCTION TO PLANT EQUIPMENTS
Combined cycle power plants are installed now days at many places in our country.

15. 15
1.0 Gas Turbine Equipment’s: -
1.1 Compressor:
The atmosphere air is compressed to the 17-stage compressor and before it passes through the
filter. The compressor ratio is 10 and this air is routed to the combustors.
1.2 Combustors:
The fuel (gas) is provided to ten equal flow lines, each terminating at a fuel nozzle
centeredintheend plate of a ten separate combustion chamber and prior to being distributed to
the nozzles, the fuel is actually controlled at a rate consistent with the speed and load
requirements of gas turbine. The nozzle introduces the fuel into the combustion chambers where
it mixes with the combustion air and is ignited by the sparkplugs. At instant when fuel is ignited
in one combustion chamber, flame is propagated through connecting crossfire tubes to all other
combustion chambers.
1.3 Transition pieces:
The hot gases from the combustion chambers expand into the ten separate transition pieces and
from there to the three-stage turbine section of the machine.
1.4 Turbine:
There are three stages of the turbine and each consists of a row of fixed nozzles followed by a
row of rotating turbine buckets. In each nozzle row, the kinetic energy of the jet is increased
with an associated pressure drop and in each following row of a moving buckets, a portion of the
kinetic energy of the jet is absorbed as useful work on the turbine rotor.
1.5 Exhaust:
After passing through the third stage buckets, the gases are directed into the exhaust hood
diffuser which contains a series of turning vanes to turn the gases from an axial direction to a
radial direction, thereby minimizing exhaust hood losses. The gases then pass into the exhaust
plenum and are introduced to atmosphere through the exhaust stack or to the H.R.S.G.
2.0 Gas turbine support system and their equipment: -
2.1 Starting system:
2.1.1 Diesel Engine:
Diesel engine/starting motor/Main generator with static frequency converter. Diesel or starting
motor with torque converter or main generator with SFC is used as a starting device for gas
turbine. We have Detroit make diesel engine of 590 hp for starting purpose.
2.1.2 Torque Converter:
It transfers torque from DG to Gas Turbine. It is a hydraulic coupling which transfers torque
from zero speed to self sustaining speed of Gas Turbine (i.e. about 60% speeds).
2.1.3 Accessory gear box:
It accommodates following equipments
----Main lube. Oil pump
----Main hydraulic pump
----Main fuel oil pump
----Atomizing air compressor

16. 16
2.1.4 Hydraulic ratchet:
It rotates the turbine shaft when gas turbine is on cool down. It also helps while break away of
Gas Turbine during starting. It consists of a ratchet mechanism operated by hydraulic device. Oil
is supplied by a DC driven positive displacement pump
2.1.5 Jaw clutch mechanism:
It transmits power from Diesel Engine or Ratchet Mechanism to Gas Turbine through Torque
Converter for starting of Gas turbine or at the time of ratcheting.
2.2 Lubricating oil system:
Major equipment of the system is-
2.2.1 Oil Reservoir:
The capacity is 3300 gallons. The total system requirement is 3500 gallons.
2.2.2 Lubricating pump:
Main lube oil pump is accessory gear driven. Also, for starting a/c power driven lube oil pump
of 175m head and 460gpm flow is provided. For emergency purpose DC pump of 91m head and
250 gpm flow is provided. During emergency pump in service filter remain bypass.
2.2.3 Heat exchanger:
Two coolers are provided for cooling oil each of 100% capacity.
GAS SKID:
The function of the gas conditioning skid is to supply gas to Gas Turbine free from condensate
and gas particles.
Scrubber:
The function of the scrubber is to remove condensate from gas by centrifugal action by the use
of no. parting plates within the scrubber itself. There is a provision of solenoid operated drain
valve for removal of condensate which is sensed by a level switch.
Filter:
The function of filter is to remove any foreign particles from the gas and to supply totally clean
gas. These filters are of cartridge type and replaceable if d.p across the filter increases.
Pressure control valve:
The function of the pressure control valve is to regulate down steam pressure up to 22kg/cm2
if
upstream pressure is more. This is the designed value for inlet the gas stop ratio control valve.
Condensate tank:
All the condensate collected at the bottom of the scrubber is routed to the tank through drain
piping. For this is a level controller on the scrubber which will operate on maximum and
minimum level scrubber.
Air intake system:
Filters:
There are 396 no. of filters connected in different rows. These filters are made up of cellulose
fiber.
Filter cleaning:

17. 17
Reverse pulse self cleaning system is provided for cleaning of these fibers. Processor air is used
for these pulsations. Each row is given reverse pulse at fixed time interval and in predefined
rotation.
Air processing unit:
The air from the compressor output is taken to finned tube to cool it and is passed through the
dryer for removing moisture.
2.5 Cooling and Sealing air system:
Air for the bearing sealing is extracted from the 5th
stage of the compressor. Centrifugal removes
dust and other foreign particles. Two centrifugal blowers are provided for turbine shell cooling.
2.6 Ventilating system:
Being a closed system, air circulation is provided by following ventilating fans in different
compartments:
1. Accessory and gas turbine compartment vent fan-2 no.
2. Load gear compartment -2 no.
3. Gas valve compartment vent fan -1 no.
4. Load gear oil vapors fan-1 no.
2.7 Gas turbine and compressor cleaning system:
Compressor washing skid consists of:
a) Water tank with heaters,
b) Water pump,
c) Detergent pump,
d) Water wash valve (electrically operated).
Rice hopper is provided at compressor suction for solid compound cleaning of compressor.
3.0 Reducing gear box: -
Gas turbine speed is 5100rpm, but generator speed is designed as 3000rpm, so reducing gear
box is provided to reduce speed to 3000 rpm.
4.0 H.R.S.G and Steam Turbine equipment: -
4.1 H.R.S.G:
HRSG is a horizontal, natural circulation, bid rum, dual pressure unfired water tube boiler. It is
designed to generate HP steam at 62kg/cm2
pressure and 483 deg C temperature with 59.9 t/hr
steam flow. LP steam is generated at 5 kg/cm2
pressure and at saturated temperature with
10.9t/hr steam flow. These H.R.S.Gs are having facilities of HP and LP bypass systems 100%
for both the circuits to match the rated parameters(pressure and temperature) while starting the
H.R.S.Gs and to minimize the losses of water and heat while shutting down the m/c. These are
also useful when STG trips and to keep boiler in service. Major equipments of recovery boilers
are:
1) Diverter damper and its seal air fan,
2) Super heater,
3) Evaporator (HP & LP),
4) Economizer (HP-1, 2 & LP)
5) CPH
6) Stack (height)
4.2 Steam Turbine:
The HP Steam Turbine is drawn from HP steam header of H.R.S.G 1&2. The HP steam
parameters of the HP steam are 60kg/cm2
pressure and 480deg C temperature. The LP steam to

18. 18
turbine is drawn from LP steam header of HRSG 1&2. The LP steam parameters of LP steam
are 4.3kg/cm2
pressure and 148 deg C temperature.
4.3 Condensate circuit equipment:
It consists of condensers, ejectors, extraction pumps, gland steam condenser.
4.3.1 Condenser:
It is a two pass condenser having 9084 no. of tubes having cooling surface area of 3070m2
. It
has steam condensing capacity of 137t/hr, cooling water flow of 7050m3
/hr.
4.3.2 Ejectors:
Two no. of two pass ejectors are provided each having a capacity of handiling15kg/hr dry air
49kg/hr air-water vapor mixture. One starting ejector is also there of 220kg/hr of dry air
handling capacity at a suction pressure of 0.33 atmosphere.
4.3.3 Extraction pumps:
Two no. of pumps each of 100% capacity in the system. Each has a capacity of 95 m head and
186m3
/hr flow.
4.3.4 Gland steam condenser:
Steam leaking from turbine glands is used to raise the temperature of the condensate by GSC.
Two no. of fans are provided for extracting steam.
4.4 Feed water circuit:
It consists of the feed water tank, HP & LP feed water pumps.
4.4.1 Feed water tank:
It is mounted at elevation of 9m so it provides a net positive suction head to the boilers feed
pumps. It also has a dearator at the top of the tank for mechanical dearation of the feed water.
4.4.2 HP feed pumps:
Three feed pumps of 50% duty are provided to feed h.p water to boiler. Each is a KSB make,
multistage pump with discharge head of 925m and 75m3
/hr.
4.4.3 LP feed pumps:
Three feed pumps of 50% duty are provided to feed l.p water to the boiler. Each is a Beacon
Water make, multistage pump with discharge head of 117m and 11.5m3
/hr.
5.0 common support system for GT and ST:-
5.1 CW and ACW systems:
There are three CW pumps each of 50% capacity of 23 head and 3850t/hr flow. They circulate
water in steam turbine condenser and ST oil cooler. There are three ACW pumps each of 50%
capacity of 34m head and 576t/hr flow. They circulate water in following gas turbine auxiliaries:
A) Diesel engine,
B) Lub. Oil coolers,
C) Generator air coolers.
It also circulates in feed pump bearing, coolers of AC plant, air
compressors, ADUs and boilers water sample coolers.
5.2 Air compressors:

19. 19
Air is required for the following purposes:
a) For pneumatic operations of all control valves,
b) At different maintenance work places for cleaning,
c) If required it can be used for GT filter cleaning.
There are three kirlosker make horizontal, balanced opposed piston compressor each of
8.1kg/cm2
head and 253 Nm cu. /hr air flow. Air from the receiver tank is directed to air drying
unit to moister free.
5.3 Raw water system:
Three no. of bore wells supply raw water to a water reservoir from which is transferred to water
treatment plant by use of raw water pumps each of 125t/hr flow capacity. Each bore well is of @
125 to 150t/hr flow capacity. Daily raw water consumption of the plant is around 4000t.
5.4 Laboratory:
Any power plant requires soft water and dematerialized water in large quantity. There are soft
water plant (cap 7.2 t/hr*2) which is used in the boiler water circuit. Apart from that, a
continuous watch is kept of water chemistry of HRSG water to keep its parameters (such as ph.
and conductivity) within a specified range.
5.5 Fire protection systems:
It includes no. of water pumps, halon & CO2 bank, nozzle and piping net work, flame and
smoke detectors and emulsifies. There are three types of water pumps:
a) Hydrant pump (Motor and DE operated),
b) HVWS pump,
c) Jockey pump.
5.6 Black start D.G set:
In the event of total power failure, GT can be started with the help of diesel generating set (500
KVA, 680 Amp. Max) which is capable of supplying power to the bare minimum requirements
of the auxiliaries of one gas turbine. Later, other auxiliaries can be started with the help of
running gas turbine.

20. 20
CONSTRUCTIONAL DETAILS OF GAS TURBINE
Compressor Section
General:
The axial -flow compressor consist of the compressor rotor and the enclosing casing. The inlet
guide vanes, the seventeen stages of the rotor and stator balding and the two exit guide vanes
are included with in the compressor casing .
In the compressor, air is confined to the space between the rotor and stator balding where it is
compressed in stages by a series of alternate rotating (rotor) and stationary (stator) aerofoil -
shaped blades. The rotor blades supply the force needed to compress the air in each stage and
the stator blades guide the air so that it enters the following rotor stage at the proper angle. The
compressed air exits through the compressor discharge casing to the combustion chambers. Air
is exerted from the compressor for turbine cooling bearing sealing and, during start-up, for
pulsation control.
Rotor:
The compressor rotor is an assembly of fifteen wheels two stub shaft, through bolts, and the
compressor rotor bulkhead. The first stage rotor blades are mounted on the wheel portion of the
forward stub shaft.
Stator:
The stator (casing) area of the compressor section is composed of five major sections:
(1) Inlet Casing
(2) Inlet Guide Vanes
(3) Forward Compressor Casing
(4) Aft Compressor Casing
(5) Compressor Discharge Casing
Combustion Section :
General:
The combustion system is the reverse flow type and comprises ten combustion chambers
with liners, flow sleeves, transition pieces and crossfire tubes. Flame detectors, crossfire tubes,
fuel nozzles and spark plug igniters are also part of the complete system. Hot gases, generated
from the burning of fuel in the combustion chambers, are used to drive the turbine.

21. 21
Combustion Chambers:
Discharge air from the axial-flow compressor enters the combustion chambers from the cvity at
the center of the unit. The air flows upstream along the outside of the combustion liner towards
the 1 inner cap. This air enters the combustion chamber reaction zone through the fuel nozzle
swirl tip(when fitted) and through metering holes in both the cap and liner .When the nozzles
supplied are not of the type fitted with a swirl tip, the combustion chambers are fitted with a
turbulator system.
The hot combustion gases from the reaction zone pass through a thermal soaking zone and then
into a dilution zone where additional air is mixed with a combustion gases. Metering holes in the
dilution zone allows the correct amount of air to enter and cool the gases to the required
temperature. Openings located along the length of the combustion liner and in the liner cap
provide a film of air for cooling the walls on the liner and cap. Transition pieces direct the hot
gases from the liners to the turbine nozzles.
The ten combustion chamber casings are identical with the exception of those fitted with spark
plugs or flame detectors.
Spark Plugs:
Combustion is initiated by means of high-voltage, retractable -electrode spark plugs installed in
two of the combustion chambers. This spring -injected and pressure -retracted plugs receive
their energy from ignition transformers. At the time of firing, a spark at one or both of these
plugs ignites the combustion gases in a chamber. The gases in the remaining chambers are
ignited by crossfire through the tubes that interconnect the reaction zones of the remaining
chambers. As rotor speed increases, chamber pressure causes the spark plugs to retract and the
electrodes are removed from the combustion zone.

22. 22
STG: A BRIEF INTRODUCTION
Steam Turbo generator in Ramgarh Gas Thermal Power Plant is of the capacity of 37.5 MW and
STG runs in combined cycle mode utilizing waste heat of exhaust gases of GT-1 (capacity
35.5MW) and GT-2 (capacity 37.5 MW).In such Combined Cycle Power Plant higher thermal
efficiency is achieved as compared to coal based thermal power plant . Brief Introduction of the
parts /equipment of the STG power plant are as follows:-
1. Turbine:
The function of the turbine is to drive the generator at a speed of 3000 rpm. The heat energy of
steam (enthalpy) is converted in mechanical energy as steam expands in turbine. Before entering
the main steam in turbine it passes through emergency stop valve and control valve located at
turbine floor, there are 53 stages in turbine, one stage consists of a set of fixed blade mounted on
inner casing and rotary blade mounted on turbine shaft. LP injection is connected after 43 stages
of turbine. The turbine shaft is supported by the front bearing (Journal & thrust bearing) and the
rear bearing (Journal bearing) .The axial thrust produced in the moving blades is balanced by
balancing drum located in the front side of turbine. The residual thrust forces of turbine that
have not been compensated by balancing piston are taken up by the front thrust bearing .The
rear bearing of turbine houses the oil hydraulic turning device used for running the turbine on
bearing gear. Turbine gland sealing is done to avoid air entry initially at both gland ends at in
running to seal the LP end gland. When turbine is running sealing is done through turbine leak
steam itself and balance steam flows to condenser.

23. 23
Turbine oil system:
Main oil Tank (MOT):
MOT is located on 5m. It serves for storing the oil volume required for governing and
Lubrication system .Oil vapor in oil tank are vented out by an oil vapor exhaust fan installed at
the top of MOT. The MOT is provided with oil centrifuge inlet connection at bottom and the oil
centrifuge return is connected back to oil tank. The oil centrifuge cleans the oil stored in MOT.
MOP:
Lubrication oil needed for turbine bearing, governing oil system and barring gear is supplied by
MOPs .The bearing Lubrication oil is supplied after cooler and duplex filter but governing oil
and barring gear oil flows directly from the MOP discharge header.
Discharge Pressure -- 10.2kg/cm2
Flow -- 150 m3
/hr
Motor rating --55 KW, 93 A
Standby pump comes in service at header pr below --6.5 Kg/cm2
DC EOP:
In case of tripping /non availability of both MOPS ,DCEOP server for supplying oil for bearing
cooling .The emergency oil pump cuts in automatically when oil header pr falls below 0.9
Kg/cm2
in the event of further pressure fall in header, Oil shall be fed from an overhead oil tank
placed about 6.5 m over the turbine.
Jacking Oil Pump (JOP):
In the case of start up and shut down, on barring gear it is necessary to supply the high oil pr to
lift the shafting system slightly so as to avoid metal to metal contact. Friction between shaft and
bearing. For these purpose two nos. JOPS are provided; one is AC-JOP and another is DC-JOP.
2. Heat Recovery Steam Generator (HRSG):
Two no. of HRSG Established; one each for steam generation utilizing waste heat of exhaust
gases of GT1 GT2 respectively .HSRG is natural circulation Unfired Steam Generator Feed
water coming form BFP discharge passes through the tube bunches of different modules of
heat transfer surfaces and gets heated by gas turbine exhaust flowing in surrounding duct. HRSG
has nine heat transfer surfaces as mentioned below:
(i) High Pressure Super Heater
(ii) HP-evaporator including HP drum
(iii) HP-Economizer for preheating the feed water entering in drum. These are three in nos.
(iv) LP- Super Heater
(v) LP- Evaporator including LP drum
(vi) LP- Economizer
(vii) Condensate preheated (CPH) for heating condensate water before flowing to
Deaerator.
Gas cycle in HRSG:
HP Super Heater -- HP Evaporator -- HP Eco III -- LPSH --LP Evaporator -- HP Eco II -- LP
Eco -- HP Eco I – CPH – Chimney
3. Generator

24. 24
MW -- 40.8
Pf -- 0.80
MVA -- 51
Stator volt -- 11Kv
Stator current -- 2677A
Rotor volt -- 246V
Rotor amp -- 717A
Cooling -- air (which is further cooled by ACW water in air cooler located at 0 m.)
4. Water & Steam cycle equipment:
Water & Steam cycle:
Main water and steam cycle:
Deaerator -- HP BFP --Feed water control station --HP Eco -- HP drum –HP SH--Turbine (HP
Steam) --Condenser --CEP--Ejector --GSC--CPH --Deaerator control valve station --deaerator.
For LP MS another cycle sub-path through LP BFP is maintained:
Deaerator --LP BFP --LP Eco --LP drum --LP SH -Turbine (LP Injection Steam)
Equipment Description:
a) Deaerotar (Physical Location- Between HRSG 1 & HRSG 2):
It is in two parts; One is Deaeroting column where Deaeration takes place in spray valve cum
tray chamber and another is feed water storage tank which is used as water reservoir tank with
capacity of 27.5 m3
.Whole assembly is known as Deaerotar. Steam pegging is also done in
Deaerotar to increase Deaerotion, feed water temp and BFP suction pressure .Condensate
discharge through CPH (condensate preheater comes here in a chamber with 12 spray valve and
9 tray s and Deaeration takes place. Air comes out of the air vent and water flows down in
reservoir feed water Storage tank.
Deaerotar level --normal -- 0 mm
Low (alarm) -- (-) 400 mm
Very low (tripping of BFP) -- (-) 1500 mm
b)HP BFP (physical location: below Deaerotar and between HRSG 1 & HRSG 2) -
High pressure Boiler feed pumps are three in nos. and two are continuously running for full load
operation. Its full load parameter is as follows-
Discharge pr ---133.5 kg/cm2. Another HP BFP comes in operation on auto at header pr 124
kg/cm2 and
HP BFP trips at 120-kg/cm2 discharge pressure.
Discharge flow-77.5m3/hr
Motor rating ---6.6 kV; 425 kW
Full load current ---43.5. A
HP BFP cooling –
(i) oil cooling for bearing and oil level around 1/2 of the pot
size in maintained in oil pot
(ii) Seal water cooler for cooling DM water, which is used
for sealing the gland. The flushing DM water is further cooled in seal water cooler
by ACW water.
(iii) ACW cooling for bearing oil chamber.
Permissive for starting HP BFP --
(i) Suction valve open
(ii) Rdy to start -i.e. switchgear remote clearance signal is ok
(iii) deaearator level ok-above
(iv) Pump bearing temp normal -below 80 deg

25. 25
(v) Motor brg temp normal -below 80 deg
(vi) Motor winding temp normal -below 80 deg.
One recirculation line tapped from discharge line is connected to deaerator to facilitate minimum
discharge flow while BFP is running .The balance leak off line taped from impeller intermediate
stage is also connected to deaerator to balance thrust. The manual valves of these lines located at
deaerator floor should be kept open at the time of starting BFP. Manual suction valve and
motorized discharge valve are located at the floor just above BFP. All the three discharge valves
are opened while starting first BFP on auto.
C) LP BFP (physical location: below deaerator and between HRSG 1 & HRSG2):
LP BFPS are similar in constructions and operation as HP BFP mentioned above but with very
low capacity as compared to the HP BFP .Its full load parameter are as follows:
Discharge pr ---15.28 kg/cm2 .Another stand by LP BFP comes in operation on auto at
header pr 15 kg/cm2
And LP BFP trips at 14 kg/cm2 discharge pressure.
Discharge flow ---22.9m3 /hr
Motor rating ---415v; 22.0 kW
Full load current ---37.8 A
LP BFP cooling –
(i) Oil cooling for bearing and oil level around1/2 of the post size is
maintained in oil pot.
(ii) Seal water cooler for cooling the DM water which is used for
sealing the gland .The flushing DM water is further cooled in seal water cooler
by ACW water.
(iii) ACW cooling for bearing oil chamber.
LP BFP tripping ---
(i) Discharge pressure --14kg/cm2
(ii) deaerator level is very low-(-)1500mm
Permissive for starting LP BFP --
(i) Suction valve open
(ii) Rdy to start -i.e. switchgear remote clearance signal is ok
(iii) deaearator level not low i.e. above(-) 400 mm
D) Condenser –
Turbine exhaust is connected to condenser. Condenser here used is surface condenser.
Circulating water pump discharge water flows through condenser tubes &cools steam in
surrounding areas coming out of turbine. Hot well is bottom part of condenser where condensate
resulting from condensation of steam is collected and we can add make up water here to
compensate line losses of closed water cycle.
Condenser pressure -- (-) 0.9 kg/cm2 low -- very low Howell level ---0 mm (normal)
Condenser cooling water temp. --33.0 deg
e) Condenser Extraction pump (physical location at (-) 1m level) : Condensate Extraction
pump ( CEP) are three in nos. and out of them two pumps run for full load operation .These
vertical pumps are used to facilitate pumping the condensate back to deaerator .
Discharge pressure ----14.8 kg/cm2
Flow----107 m3/ hr
Full load current ----123 A
Motor rating ----75 kW
Now condensate extracting out of CEP is heated injector gland steam cooler, condensate
preheated, deaerator and in economizer before reaching to steam generator so as temp is
increased up to 140 deg and thermal efficiency is improved.
a) Ejector (physical location :5m) –

26. 26
Ejectors are used to create vacuum in condenser. Starting ejector is charged initially to create
fast vacuum. Starting Ejector basically consist of a nozzle through which pressure energy of
incoming aux steam is converted in kinetic energy and passing through high velocity it
entails air from condenser and the exhausted air and steam mixture flows to the atmosphere
.Whereas in main ejector aux steam accelerating through nozzle is also being utilized in
heating CEP discharge condensate and the condensed steam flows to condenser through manual
valves instead of being exhausted to atmosphere as in case of starting ejector.
g)Gland steam cooler (GSC) (Physical location : 5m)- Here condensate flows in GSC tubes
and heated gland steam coming out of the turbine gland sealing.
h)Condensate preheater (CPH) (Physical location: HRSG drum floor) : CPH is located as a
last heat transfer surface in exhaust gas path before flowing to 70m high stack. Condensate
water flowing in CPH tubes heated through exhaust gas.
CPH inlet water temp ----48 deg
CPH outlet water temp---94.7 deg
Flow ---136.8 t/hr
5. HP bypass & LP bypass (HPBP& LPBP) :
HPBP and LPBP are used to bypass the turbine rolling parameter is achieved. HPBP line is
tapped off from individual HRSG MS line and valves are located at 5 m in front of condenser.
Similarly LPBP line is tapped off from individual HRSG (LP system) and one valve is located in
the front of condenser at 5m and another is behind the condenser at separate platform. HPBP &
LPBP dumps MS directly to condenser after reducing pressure .Downstream temp are reduced
in case of HPBP by spraying BFP discharge water.
HPBP /LPBP control valves flows on following protections:
HPBP /LPBP solenoid valve open on protection.
(i) Generator circuit breaker open
(ii) Turbine tripped
6. Auxiliaries:
(i) Circulating water pump (CW pump):
These are three in nos. and located in pump house .These pumps are used for circulating
water through condenser tubes so as to condense the turbine exhaust steam
Discharge pr---2.5kg/cm2
Flow--- 4500 m3/hr
Full load current ---43 A
Motor rating ---400kw, 6.6kv
(ii) Auxiliary cooling water pump (ACW pump): These are two nos. and also located
in pump house. These pumps are used for following purpose:
(a) BFG brg and seal water cooling
(b) Generator air cooling
(c) Compressor lubes oil cooling
(d) Turbine bearing oil cooling
(e) In GT area for gas booster compressor and atomizing air cooler ACW pumps
along with CW pumps take suction from pump located underground beneath them and return is
cooled by cooling towers.
Discharge pressure ---4.5 kg/cm2
Flow ---655 m3 /hr
Full load current ---215 A
Motor rating ---125 Kw, 415v

27. 27
D.C. SYSTEM
D.C. system of the power plant is considered as the heart of the power plant. Every controlling,
signaling, annunciation system depends on DC system of the power plant. Reliability and
availability are the main quantities of the DC system. The D.C. system of the power plant
consists mainly of three components.
1) Battery System,
2) Charger System,
3) D.C. Distribution System.
1) Battery System:
Battery is the core element of the dc system. Batteries are the only known means of
power storage which can be used in emergency and zero power condition.
2) Charger System:
Charger is basically a rectifier which converts ac power into the dc power. It can be
controlled rectifier and uncontrolled rectifier
Chargers for power station duty are normally designed to supply the dc power
requirement of the station.
Charger is required to perform two types of duties-
1. Float Charging:
In this mode the charger supplies the station the dc load and simultaneously trickle
charges the battery. In this mode the battery just floats on the system.
2. Boost Charging:
When ac supply to the charger fails, the battery takes care of the dc load. While doing so the
battery discharges reducing both its voltage and specific gravity. When ac supply restores the
charger takes up the dc load and also feeds the charging current to the battery. Requirement of
the charging current is quite large hence this mode is called Boost Charging Mode.
In boost charge mode the main function of the charger is to charge the battery at a high current
rate. This is achieved by increasing the charger output voltage. If this increased voltage is also
applied at the load terminals, the equipments connected such as closing & tripping coils of
breakers, components of power supplies units like dc/ac converters may get damaged. To
prevent this following two methods are adopted.
a) Diode Dropper Circuit:
In diode dropper circuit, no of diodes no. of diodes are placed in series between charger and
battery terminals. (Refer plate 2). These diodes will drop the excessive voltage and maintain
rated voltage on load terminals. The drop across diodes results in heat generation and proper
ventilation in the charger is required.
b) Battery Tape Diode Circuit:

28. 28
In battery tapped diode circuit the battery bank is tapped at a point whose voltage is equal to
system rated voltage during boost charge condition. This tapping is connected to the load during
boost charging. Thus increased voltage is available across the battery and rated voltage is
maintained at the load terminals.
Some chargers are designed to work on constant voltage/constant current mode. In CV mode
charger will maintain the constant voltage across the across the load terminals. In CC mode it
boosts the battery with the constant current. In some chargers the float/boost mode is
automatically selected by sensing the battery current. A shunt is provided in the connection from
charger to battery. Millivolt drop across this shunt is used to select the mode. If this drop
exceeds predetermined limit, the charger goes in the boost mode pumping high ampere into the
battery. As the battery gets charged, the charging current reduces the charger returns back to the
float mode.
1) 110V D.C System for Station Service:
This provides dc controlling to all the equipments such as relays, breakers, isolators etc. It also
supplies emergency dc lightning of the station. It consists of one main charger. Both the charges
have float/boost facility. These are backed by 1200AH station battery. Boost charging is
facilitated by battery tap diode.
2) 125V System for Gas Turbine:
There are two independent systems for GT-1 & GT-2. It takes care for dc requirement of gas
turbine control and also supplies dc auxiliaries like lube oil pump, hydraulic ratchet etc. its
charger has bloat/boost facility. When ac power resumes after disturbance the charger
automatically goes in boost mode for a predetermined time which can be set by the operator. Its
back up battery is 400AH.
3) 110V D.C System for Steam Turbine:
This takes care for dc turbine system controls. It is equipped with one float charger, one boost
charger and one float cum boost charger. Battery tape diode is used for boost charging the
battery. The backup is 1000AH.
4) 360V D.C System for U.P.S. :
Many systems in data acquisition and control room secondary equipments such as recorders etc.
need reliable ac power. A U.P.S System is provided for the same which consists of an inverter
circuit to convert dc power to ac power. The dc power of this System is by means of 360V,
250AH backup battery.
5) 24V D.C System for D.C.S:
The distributed control system of the plant needs 24V dc. Two independent 24V dc Systems are
provided. These systems are terminated on a common dcdb separated by a bus coupler. The
charges are provided with CV/CC modes. In CV mode it supplies dc load and floats the battery.
In CC mode it only boost charges the battery. Here the battery tap diode or diode dropper circuit
is not provided but the load itself is disconnected from the charger to prevent increasing voltage
appearing on load terminals. The reliability of load dc is taken care by other means at D.D.C
end.

29. 29
EXCITATION SYSTEMS AND A.V.R
The synchronous generators require excitation in its rotor to generate the ac power. Various
means are available to feed the excitation to the generators.
1) Conventional D.C. excitation:
Earlier generators were directly fed from station dc system. Rheostat was provided in series with
the field winding to adjust the excitation current and subsequently the terminal voltage and
reactive power of the generator.
2) D.C Exciters:
The dc generators are provided with directly coupled pilot and main exciters. Pilot exciters feed
main exciter which in turn feeds the generator rotor winding. The excitation current control is by
means of series rheostat and amplidynes. This type of excitation system is used for T/A-15 &
T/A-16 in ‘c’ station at Sabarmati Power Station.
3) A.C Exciters:
In this system the generator is provided with shaft driven ac pilot exciter having rotating
permanent magnetic field and stationary armature. The output of stationary armature is rectified
by diodes and fed to rotor via slip rings.
4) Static Excitation System:
In this case the ac power is tapped from the generator terminals itself, stepped down and
rectified by controlled rectifiers and then fed to generator via slip rings.
5) Brushless Excitation Systems:
In order to reduce the operational problems involved in injecting high current by means of slip
rings, brushless excitation system is developed. In this system the rectifier diodes are mounted
on the generator shaft and their output is directly fed into generator field thus eliminating the
slip rings and brushes.
Excitation system at RGTPP
The components of the system are as follows-
1) Permanent Magnet Pilot Exciter:
This is a six pole exciter. The stator houses three phase winding and permanent magnet poles are
mounted on the shaft. The exciter generates 3 phases, 150Hz voltage. These are taken to AVR
for further controlling.
2) Main Exciter:
The main exciter is six pole rotating armature and stationary field type. The field winding is fed
with the controlled current from the AVR.

30. 30
3) Rectifier Wheel:
This as name suggest comprises of silicon diodes mounted on the rotating wheel and arranged in
3 phase bridged configuration. 3 phase ac from main exciter armature is fed to this bridge. The
dc output is injected into the generator field via specially designed contacts.
4) A.V.R.:
The voltage regulator receives dc voltage from permanent magnet generator controls it and
supplies to the main exciter field.
The main purpose of the voltage regulator is to supply the excitation to the generator and to
maintain the terminal voltage of the generator.
The main components of AVR are two closed loop controls system including Thyristor Bridges,
gate controlled, field discharge circuit and an open loop control system for communicating with
the signals from the control room.
The first closed loop of regulator controls the generator voltage via the gate control of the
thyristors so as to provide to quick correction of the generator voltage and changing generator
loads. The gate control set changes the firing angle of the thyristors as a function of the output of
the closed loop.
The main quantities acting on the input of the regulator are the set point and the actual value of
generator voltage. The set point is divided into the basic set point (90% of rated voltage) and an
additional value which can be controlled from the control room (90% to 110%)
The actual value of generator voltage is taken from potential transformer and is compared with
the set point. The difference signal is amplified and fed to the gate control set.
The other closed loop system, manual controls the excitation current in the main exciter field
winding. Thud it acts as an exciter current controller rather than generator voltage controller.
The regulator normally operates on the first loop that is an auto loop, normally referred as auto
control channel. The manual control loop or manual channel is used during generator
commissioning to obtain generator characteristic. Manual control also takes over during the
failure of the auto control.
Field breaker
The field winding of the rotor is fed via a special dc breaker so that under any disturbance the
field is disconnected from the source and simultaneously the magnetic energy stored is
discharged. For this purpose field discharge or field suppression resistors are provided. For
small resistors linear generators are employed. For large generators voltage dependent resistors
made of silicon carbides are used to enable fast de-excitation.
Electronic Field Suppression
Normally in such types of AVR, the field discharge command first drives the thyristor set to
maximum negative output voltage (inverter operation) via gate control. This causes the main
exciter to be de-excited in less than 0.5 seconds. Generator de-excitation follows depending
upon generator time constant. The field breaker is tripped after the inverter operation of the
thyristor. The field breaker and field discharge resisters are designed to affect field suppression
even in case of failure of electronic field suppression.
Limiters
With increasing size of generator and grid stringent requirements have to be net by excitation
system. The excitation system has to ensure stable operation under both dynamic and transient

31. 31
conditions. Generators running in parallel must remain in synchronism without the maximum
load limit being exceeded and without its protective relays operating.
The basic AVR is armed with other circuits known as limiters or controllers to ensure the
above.
These limiters work in conjunction with AVR to ensure
1. optimum utilization of machine
2. security of parallel operation even under transient conditions
a) Over excitation limiter or rotor current limiter
When the system voltage drops due to increased reactive power requirements or external
faults, the regulator increases the excitation to the generator in order to maintain the
generator terminal voltage. This may results in thermal overloading of exciter and
generator rotor.
b) Stator current limiter
This limiter avoids thermal overloading of stator winding. The stator current of generator may
increase because of –
1. Excessive inductive load or
2. Excessive capacitive load.
The corrective action of stator current limiter is different in both cases. During excessive
inductive loading it reduces the excitation to limit the stator current. During excessive capacitive
loading it increases the excitation to limit the stator current.
c) Rotor angle limiter
The rotor angle or load angle is an electrical angle between the voltage vector of the system and
vector of machine voltage. The load angle limiter monitors this angle. In case the angle exceeds
the set value this controller takes over and increases the excitation to the generator to reduce the
load angle.
d) Field forcing
When voltage regulator calls for maximum excitation the thyristor supplies higher voltage to
field winding of main exciter than actually required for exciting the main exciter to ceiling
voltage. This is to reduce the exciter time response. In this case the output current of the
thyristor set is limited by the field forcing limiter to a value
e) V/Hz limiter
V/Hz limiter reduces the excitation of the generator when preset V/Hz value is exceeded. This
prevents excessive magnetic flux and thermal stressing on the unit transformer.

32. 32
CONSTRUCTION DETAILS OF
GENERATOR AND EXCITER
GENERATOR:
The generator is two pole, cylindrical rotor, air cooled type-TARI, Siemens
Design of BHEL makes.
Main components of generator are –
1.0 Stator
1.1 Stator frame
1.2 Stator core
1.3 Stator windings
1.4 Stator and covers
2.0 Rotor
2.1 Rotor Shaft
2.2 Rotor winding and retaining ring
2.3 Field connections
3.0 Bearings
4.0 Generator and air cooler
5.0 Excitation system

33. 33
STATOR:
Stator Frame:
Stator frame supports the laminated core and stator winding. It is welded construction consisting
of stator framehouing, two flanged rings, axial and radial ribs. The dimensions and arrangement
of ribs is determined by cooling air passage and required material strength and stiffness.
Ventilating air ducts are provided in the radial ribs. Footings are provided to support the stator
frame on foundation plates by means of bolts.
Stator core:
Stator core is build from silicon steel electrical grade laminations. Each lamination is made up
from number of individual segments. Segments are stacked on insulating bars which hold them
in position. One bar is kept un- insulated to provide grounding of laminated core.
The laminations are hydraulically compressed and located in frame by means of camping bolts
and pressure plates.
Clamping bolts run through the core and are made of non-magnetic steel and are insulated from
the core to prevent short circuiting of the core. Clamping fingers are provided at the ends which
ensure compression in teeth area. The clamping fingures are made up of non-magnetic steel to
avoid eddy current losses.
1.3 Stator Winding:
Stator winding is two layers short pitch winding consisting of stator bars of rectangular cross
section.
Each bar consists of number of separately insulated strands. In slot portion the strands are
transposed to ensure uniform distribution of current over entire cross section of the bar. The high
voltage insulation is epoxy cast resin type bonded with mica. The insulation is continuous, void
free, extremely low moisture absorbent, oil resistant and exhibits excellent electrical, mechanical
and thermal properties. A coat of semi conducting varnish is applied over the surface of all bars
within the sot range to minimize corona discharges between and slot wall.
All the bars are additionally provided with end corona protection to control the field at that
location and to prevent formation of creep age sparks. Several layers of semi conductive varnish
are applied at varying lengths to ensure uniform electric field. A final wrapping of glass fabric
tape impregnated with epoxy resin is provided which serves as surface protection.
The stator bars are inserted in slots with very small clearances. At the top they are secured by
slot wedges and ripple springs. In the end windings the bars are firmly lasted to supporting
brackets. Spacer blockers are placed between the bars to take care of electromagnetic forces that
may be produced during short-circuits.
The beginning and the ends of the three phase winding are solidly bolted to output leads with
flexible. Output leads are copper flats inserted into insulating sleeve.
1.4 Stator End Covers:
Stator and covers are attached to the end flanges of stator frame and rest on a foundation frame.
The end covers aluminum alloy castings.

34. 34
ROTOR:
2.1 Rotor Shaft:
The rotor shaft is single piece solid forging. Slots for winding are milled into rotor body. Axial
and radial holes are provided at the base of the rotor teeth forming air cooling ducts.
2.2 Rotor Winding:
The rotor winding consists of several series connected coils which form north and south poles.
The conductors have rectangular cross section and are provided with axial slots for radial
discharge of hot air. Individual conductor is bend to obtain half turn. After insertion into slots
these turns are brazed to form one full turn. Individual coils are series connected so that one
north and one South Pole is obtained. Conductors are made of copper having 0.1% silver
content to provide high strength at higher temperatures so that coil deformations due to thermal
stresses are avoided. Individual turn of the coil is insulated with glass fiber tape. Glass fiber
laminates are used slot insulation.
To protect the winding against the effects of centrifugal forces the winding is secured in the slots
with wedges. Slot wedges are made from alloy high strength and high electrical conductivity
material. This also acts as damper winding. At the ends, slot wedges are short circuited through
the retaining ring which acts as short circuiting ring to induced currents in damper windings.
Retaining rings of high strength of non-magnet steel are provided.
2.3 Field Connections:
The connections of the rotor windings are brought out at the exciter side shaft end through rotor
shaft bore.
3.0 Bearings:
The rotor is supported in two sleeve bearings. To eliminate shaft currents the exciter end bearing
is insulated from the foundation frame & oil piping. Temperatures of the bearing are monitored
by two RTDs embedded in the lower half of the sleeve bearing. Bearings also have provision of
fixing vibration pickups to monitor bearing vibrations transmitted from the shaft.
4.0 Air Cooling Circuits:
The cooling air is circulated in the generator by two axial flow fans fixed at each end of the rotor
shaft. Cold air is drawn by fans from cooler compartment located at the side of the generator.
The cooling air directed into the rotor end winding and cools the windings. Some air flows in the
rotor slots at bottom duct from where it is discharged into the air gap via radial ventilating slots
in the coil and bores in the rotor wedges.
Part of the flow is directed over the stator overhang to the cold air duct and to the gap between
the stator frame and stator core. Air then flows through ventilating ducts in the core into the air
gap.
The balanced air is directed into the air gap over the retaining rings cooling it.

35. 35
5.0 Excitation System:
The excitation system is of brushless type and consists of following-
1. three phase pilot exciter
2. three phase main exciter
3. rectified wheel
The three phase pilot exciter is a permanent magnet type. Three phase output from the pilot
exciter is fed into the AVR (Automatic Voltage Regulator).From the AVR regulated dc output is
fed to the stationary field coils of main exciter. The three phase output from the rotating
armature of the main exciter is fed to the rectifier wheel, from where it is fed to the field
winding of the generator rotor through dc leads in the rotor shaft.
5.1 Pilot Exciter:
Pilot exciter is six pole units. The stator is consists of laminated core and carries three phase
winding. Rotor consists of hub on which six permanent magnets poles are mounted.
5.2 Main Exciter:
Main exciter is six pole revolving armature types. Field winding and poles are mounted on
stator. At the pole shoe the damper winding is provided. Between the two poles a quadrature
axis coil is fitted for induced measurement of armature current or generator rotor current.
5.3 Rectifier wheel:
Main components of the rectifier wheels are silicon diodes arranged in three phase bridge
configuration. Each diode is fixed in a heat sink. A fuse provided for each diode to switch off
the diode when it fails. These fuses in the diodes can be checked while generator is running,
with the help of stroboscope.

36. 36
132 KV SWITH YARD
Ramgarh GTPP contains 132 KV switch Yard. The switchyard houses transformers, circuit
breakers, and switches for connecting and disconnecting the transformers and circuit breakers. It
also has lightning arrestors for the protection of power station against lightning strokes.
The supply to the bus bars from alternators is taken through the transformers and circuit
breakers of suitable ratings.
Some components are-
1. Bus Bars:
Bus –Bars term is used for a main bar or conductor carrying an electric current to which many
connections may be made.
There are two buses of 132 KV, 800A, in Ramgarh GTPP to which incoming and outgoing
feeders, Bus Couplers, Isolators, Circuit Breakers, protective Relays, Current Transformers (CT)
and Potential Transformers (PT) are connected are connected.
One Bus is usually is called ‘main’ bus and the other ‘auxiliary’ or ‘transfer’ bus.
The switches used for connecting feeders or equipment to one bus or the other are called selector
or transfer switches.
2. Insulators:
The porcelain insulators employed in switch yard of the post and bushing type. They serve as
supports and insulation of the bus bars.

37. 37
3. Isolators:
Isolator is an off-load switch. Isolators are not equipped with arc quenching devices and
therefore, not used to open circuits carrying current. Isolator isolates one portion of the circuit
from another and is not intended to be opened while current is flowing. Isolators must not be
opened until the circuit is interrupted by some other means. If an isolator is opened carelessly,
when a heavy current, the resulting arc could easily cause a flash over to earth. This may shatter
the supporting insulators and may even cause the fatal accident to the operator, particularly in
high voltage circuits.
While closing a circuit, the isolator is closed first, then circuit breaker. Isolators are necessary on
supply side of circuit breakers in order to ensure isolation (disconnection) of the circuit breaker
from the live parts for the purpose of maintenance.

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4. Circuit Breakers:
A circuit breaker is an on-load switch. A circuit breaker is a mechanical device designed to open
or close contact members, thus closing or opening an electrical circuit under normal or abnormal
conditions. It is so designed that it can be operated manually (or by remote control) under
normal conditions and automatically under fault conditions. An automatic circuit breaker is
equipped with a trip coil connected to a relay or other means, designed to open or break
automatically under abnormal conditions, such as over current.
SF6 circuit breakers are used in RGTPP.
A circuit breaker must carry normal load currents without over heating or damage and must
quickly open short-circuit currents without serious damage to itself and with a minimum burning
contact. Circuit breakers are rated in maximum voltage, maximum continuous current carrying
capability, and maximum interrupting capability, maximum momentary and 4-second current
carrying capability.
Thus, functions of the circuit breaker are-
1. To carry fill load current continuously
2. To open and close the circuit on no load
3. To make and break the normal operating current
4. To make and break the short circuit currents of magnitude up to which it is designed
for.
5. Protective Relays:

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The protective relay is an electrical device interposed between the main circuit and the circuit
breaker in such a manner that any abnormality in the current acts on the relay, which in turn, if
the abnormality is of dangerous character, causes the breaker to open and so to isolate the faulty
element. The protective relay ensures the safety of the circuit equipment from any damage,
which might otherwise cause by fault.
All the relays have three essential fundamental elements-
1. Sensing Element, sometimes also called the measuring elements, responds to the
change actuating quantity, the current in a protected system in case of over current
relay.
2. Comparing Element serves to compare the action of the actuating quantity on the
relay with a pre-selected relay setting.
3. Control Element, on a pickup of the relay, accomplishes a sudden change in the
control quantity such as closing of the operative current circuit.
The connections are divided into three main circuits consisting of a) primary winding
of the CT connected in series with the main circuit to be protected.
b) Secondary winding of the CT and the relay operating winding and
c) The tripping circuits
Under normal operating conditions, the voltage induced in the secondary winding of the CT is
small and, therefore, current flowing in the relay-operating coil is insufficient in magnitude to
close the relay contacts. This keeps the trip coil of the circuit breaker de-energized.
Consequently, the circuit breaker contacts remain closed and it carries the normal load current.
When a fault occurs, a large current flow through the primary of the CT. this increases the
voltage induced in the secondary and hence the current flowing through the relay operating coil.
The relay contacts are closed, and the trip coil of the breaker gets energized to open the breaker
contacts.
6. Current Transformers (CT):

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A current transformer basically consists of an iron core on which are wound a primary and one
or two secondary windings. The primary is inserted in the power circuit (the circuit in which the
current is to be measured) and the secondary winding of the current transformer is connected to
the indicating and metering equipments and relays are connected.
At GTPP, current transformers are provided in switchyard to measure the current of the feeders.
There are five cores in current transformers. The 1st
, 2nd
, 4th
and 5th cores are provided for
protection and the third core is used for measurement purpose.
These CT are of the ratio of 200/1, 400/1, and 1200/1. When the rated current of CT flows
through its primary winding, according to transformation ratio the current in the secondary of
the CT will flow and will be measured by the indicating instruments connected to the secondary
of the CT.
7. Potential Transformers (PT)/ voltage transformer (VT):
At GTPP, in switchyard, there are two voltage transformers, namely VT-1 and VT-2, to measure
the voltage on the bus bars. The primary winding of the VT is connected to the main bus bar of
the switchgear installation and, various indicating and metering equipments and relays are
connected to the secondary winding. When the rated high voltage is applied to the primary of
the voltage transformer, the voltage of some specific value will appear on the secondary of the
VT, and the indicating equipments measure this.
8. Lightning Arrestors:

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A lightning arrester is basically a surge diverter and used for the protection of power system
against the high voltage surges. It is connected between the line and earth to divert the incoming
extra high voltage wave to the earth.
It consists of a linear resistance. At GTPP, it is so designed that at 132 KV its resistance remains
infinity and during lightning, when the excess incoming voltage (near about 1 crore or 10 crore)
falls on the line, this resistance, falls down to zero value and it shorts the circuit, resulting in
flow of lightning current to earth.
9. Current Voltage Transformers (CVT):
CVT are provided for synchronization purpose at feeders to measure phase angle, voltage and
frequency. For joining the feeders coming from different places or for synchronization of
feeder’s voltage, phase angle and frequency at the joining place must be of same value.
10. Wave Trap:
All the telephone lines in RGTPP are connected through Wave Trap to ensure effective
communication in emergencies.

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11. Bus Coupler:
Bus coupler is connected to couple two buses, which are provided in parallel. When fault occurs
in one bus, load of the faulted bus is transferred to the second bus.

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CONCLUSION
From RGTPP & all other power plant Collaborated with Rajasthan Rajya vidhut Utpadan Nigam
Limited (RRVUNL), we get the electricity & this generated electricity is also supplied to other
states. These all are the power generation plants.
I get the knowledge about the control system of the turbines,
Boilers etc. The WSPOSE system is the control panel of the steam turbine. By this, we control the
steam flow, level of water in boilers, temperature of the turbine & many other processes by sitting
in the control room. The other control system is MARK V control panel. Same as WSPOSE, the
MARK V control panel is used to control the processes of turbines. The main advantage of all that
control panels is that we can control the whole processes of the turbines by sitting in the control
room. We don’t need to go on the fields to operate all the machines.