1. Kohinoor Energy
Limited
Muhammad Urshyan
University Of Engineering And Technology
Lahore

2. Kohinoor Energy Limited
Contents
 Introduction
 Safety First
 Voltage System Classifications
 MV System
 HV System
 LV System
 Other Systems
 Fuel System
 Booster System
 Cooling System

3. Kohinoor Energy Limited
Introduction
Kohinoor energy Limited commonly known as KEL is a 124 MW power plant
situated at Raiwand bypass. It is basically a thermal power Plant having eight 15 MW
synchronous generators having diesel engines as their prime movers and a 6 MW
generator having steam turbine as its prime mover whose steam is created by the
exhaust gases of the engines . Fuel being used for running the generators and the steam
turbine is High Fuel Oil(HFO). LFO is also being used for running the generators for
servicing purposes.
Electricity is being generated at 11kv and then stations transformers
are used to step down the voltage level a part of the generated electricity to 404 volts and
this Voltage is used to run the auxiliary system of the Plant itself . voltage level is
increased to 132kv by using three main transformers and then its fed to the grid station.
From grid station the electricity is transmitted to Wapda according to their requirement .
Fig.1. Kohinoor Power Plant

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Safety First
“Safety First” is the basic Working principle of KEL where human life is
prioritize over anything else. The plant as a whole along with its regulations is a
sheer demonstration of that motto. Following are a few gestures that elaborate this
principle.
 Compulsory Safety outfit
 Sophisticated Fire extinguishing system
 Abundant sign boards
1. Safety Outfit
A safety outfit equipped with the personal protected instruments is made
compulsory for all the workers entering the plant area.
This outfit includes the following entities:
 Bolier Suit
 Safety Shoes
 Safety helmet
 Ear Muffs
 Safety Goggles
 Cotton gloves
 Walky Talky Set
All the entities are used according to the level of safety precautions
needed at the place of work. i.e Places like workshop have low risks so a few entities can
be skipped but at places like engine room require the usage of all of them. Fig.2
demonstrates the proper usage of the whole equipped outfit.
2. Fire Extinguishing System
A very sophisticated fire alarm and fire extinguishing system has been installed
in the plant. This system includes the following gestures:
 Centralized Extinguisher
Centralized fire extinguishing system has been installed in the whole plant
and it is triggered by the fire sensors sensing the fire. Human Machine Interface
also shows the infected area red so that the evacuation of the workers can be
carried with less trouble and losses can be minimized to as much as possible.

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Fig.2. Proper Usage Of Personal Protective equipment

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 Fire Alarm System
Fire alarm System is been installed in the plant too along with the alerting
lights that start glowing whenever any incident occurs that can prove to be fatal ,
fire being one of them.
 Pre-Mapped Exit Path
An exit Path is been Mapped already to avoid any sort of
misunderstandings while evacuating the plant in emergency cases. Green exit
signs are displayed at every possible location to make it as easier as it can be to
make the danger as less as possible for the working body of the plant. One of
such signs is shown in the following Figure.
Fig.3. Hallway while Exiting the HV/LV workshop with
exit sign above the door

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 Portable Extinguishers
Portable extinguisher are also places abundantly at various spots of the plant
in case the centralized system or the sensors get damaged and the worker needs
tom indulge with the fire himself anyway.
Fig.4.Fire Extinguisher
3. Sign Boards
Visual instructions have always been more influencing on the human beings
rather than just audible ones . So throughout the plant sign boards bestowing the
importance of human life and explaining the possible dangers that can be faced while any
sort of negligence are places are different spots. A few vital purposes of these signs are
given as following:
 Precluding the engagement of workers with anything fatal to their lives
 Asking the workers put their safety above anything else
 Explaining the hazards workers can face while being

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Voltage System Classification
The plant has been classified into three categories considering the voltage level.
i. MV System (Medium Voltage System)
ii. LV system (Low Voltage System)
iii. HV system ( High Voltage system)
Medium Voltage System
The System operating at the 11 KV is specified as the medium Voltage
System. Majors parts to be studied at this level are given below:
Single line Diagram: Single line diagram shows the whole MV system on a single sheet or
board to show the position of all the breakers along with the regulation of the MV system.
Generators: During this internship I understood the working of synchronous generators on
practical basis. Took part in servicing a generator myself. And comprehended the protection
system of the generator.
e
Fig.5. generator engine assmebly

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Generator Protection:
A reasonable number of relayed are used to protect the generator from every
possible damage and faults. A few I observed there are given below:
 Over current relay: Over current relays are used to prevent the damages when the
current of the generator is increased from a specific peak value. These relays are
basically used for the generating the signal to turn the generators off while such
hazardous conditions occur. Normally used over current relays are electronic over
current relays.
Fig.6 Electronic overcurrent relay
The way it works is that we set a reference current and the
triggering time and then whenever the specific current limit is crossed for a specific time period
the relay triggers a signal and the breaker turns the connection off. The diagram shown in the
middle picture of figure.7 explains its functionality. How the CT’s provide the actual current in a
downgraded scale and how the relay triggers the actions.
 Earth fault relay: This relay is used for the same purpose but to trigger its action
current overshoot current isn’t a parameter it turns the breaker off with the help of the
PLC’s while the earthing Fault is detected somewhere.
 Reverse power relay: Reverse power relay is used to track the amount of the reverse
power in the circuit. In most such relays if the reverse power exceeds three to four
percent of the generated power the relay turns the breaker on.
 Over voltage relay: Over voltage relay work on the same principle as the over current
relay and the but here we take voltage as a reference rather than current and PT’s are
used instead of the CT’s.

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 Under Voltage relay: Under voltage relay does the same work as the over voltage relay
but it does it in a different manner. Whenever the generated voltage in below a certain
critical point it turns the generator off using the PLC control panel.
 Differential current protection relay: This relay takes input from two points one from
the input side and one from the output side usually and whenever the difference exceeds
a defined limits it triggers a signal that can be used to perform whatever the action
defined by the PLC. i.e turning the generator of or cutting the supply.
 Excitation loss relay: This one is used to monitor the excitation loss in the generator
,whenever it exceeds a defined limit a signal is generated that can be used to perform the
talk defined to it by the controller.
 Diode monitor relay: This one gets triggered when any problem in the diodes used for
the rectification purposes in the generator shows any problem or failure.
CT’s & PT’s:
CT’s and PT’s are used to take the step downed currents and voltages respectively
for the following purposes:
 Measurement: As meters can’t measure 11kv and 500 amperes directly we use CT’s and
PT’s to step down the currents and voltages respectively and then according to the scale
proper measurement can be done.
 Protection: The step down voltage can be fed to the relays and the controllers for the
comparisons that can decide whether all conditions all conditions of proper working are
meeting or not.
Fig.7. CT and PT in the MV switchgear

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SF6 Breaker: These breakers are used in MV system where SF6 is filled inside the breaker
where contact is to be made or broken for the absorption of the spark.
Fig.9 SF6 breaker in MV switchgear
Whenever the contact has to be made the coil gets charged and the motor presses the spring and
the connection is made and vice versa happens when the connection has to be broken. The six
connectors in figure 9 are connected with six connection places shown in the breaker box in
fig.8.
MV Switchgear: MV switchgear is basically what regulates the MV system. It consists of the
breakers and meters and buss bars. Its purpose is to basically to feed the generated electricity to
the buss bar for receiving and sending electricity to and from the transformers. .
MV Switchgear

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MV Switchgear shown above has five units and three of them are for taking
electricity from the generators and feed it to buss bar and the other two are sued to send it to the
main and station transformers. Each unit from inside has shown in Fig.8 and Fig.9.CTs PT’s and
SF6 breakers are used for the switching purposes.
Station Transformer: Station transformers are used to take the 11kv voltage and step down it to
404v for using electricity in auxiliary system. Electricity from this transformer goes to the LV
switchgear. So, primary side of this transformer contributes to the medium voltage system.
Main Transformer: From MV switchgear the generator electricity goes to the main
transformers at 11 KV where it is transformed to 132 KV and hence primary side of main
transformer also corresponds to the medium voltage system.
Transformers Protections: A reasonable number of relayed are used to protect the transformer
from every possible damage and faults. There are over current and over voltage relays just like
the generator. The relays purely used for transformers are given below:
Buckle relays: These relays are used to detect the internal faults of the transformers. Mostly
related to the fumes created inside.
Pressure relief relay: Pressure relief relay is used to detect any sort of sparks or other causes
increasing the pressure of the oil inside that can cause the breaking of the bogy. What it does it
opens the vacant paths for the passage of the pressurized fuel so that body can be saved from
damage.
Oil temperature relay: This relay gets triggered whenever the oil temperature of the
transformers increases a defined maximum temperature.
Winding temperature relay: This relay gets triggered when the winding temperature increase a
specific limit and whatever the actions assigned to the tail are performed.
Brushless Excitation: Generators used in this plant have small generators along with them to
excite the filed winding. These smaller generators induce current in the filed winding and hence
there no physical contact is required for the excitation.
Low voltage system:
The system operating at 404 or less voltages in categorized as the low
voltage system. The total auxiliary system of the plant falls into this category. The output to the
stations transformers feed electricity to the lv switch gear and that’s the first link of the lv
system.

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LV Switchgear: Lv Switchgear has its input from the output of the station transformers. Then
the auxiliary load is run by this supply.
Fig.11. LV switchgear
Tie Breaker: Tie breaker is a part of LV switchgear. It is used to shift the load of on buss bar
one transformer on the other transformer.
Fig.12. Tie breaker

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Fuse module/switch: Fuse module of switch are the fuses with the on/off switches. The purpose
is to work safely over the fuses many of these can be seen in the LV switchgear.
Magnetic breaker: Magnetic breaker are used to break the circuit whenever needed. The plates
are magnetized and the contact is made whenever the relay triggers the signal of breaking the
circuit the magnetization vanishes and the circuit breaks.
Electronic over current relay: The way it works is that we set a reference current and the
triggering time and then whenever the specific current limit is crossed for a specific time period
the relay triggers a signal and the breaker turns the connection off. The diagram shown in the
middle picture of figure.7 explains its functionality. How the CT’s provide the actual current in a
downgraded scale and how the relay triggers the actions

15. Kohinoor Energy Limited
Other System Classifications
Different systems are classified on the basis of their voltage level and functionalities a
and during my stay at the plant I comprehended the following systems:
 Fuel System
 Booster system
 Cooling System
Fuel System
The fuel System basically contains following parts
 HFO storage tanks
 Storage tank fillers
 LFO storage tank
 Day tanks
 HFO Buffer tanks
 Transfer Pumps
 Purification Plant
1. HFO Storage Tanks
There are four HFO storage tanks and they are used for the primary
storage purpose. The fuel stored in it is the unpurified HFO.
Fig.12 HFO Storage tank

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2. LFO Storage Tank
LFO Storage tank is used for the Primary storage of the tank. There is
only one LFO storage tank cause it is not needed in much quantity due to its rare
using purposes .
3. Storage tank Fillers
Fillers are used to fill HFO or LFO in their respective Storage tanks. The
fuel is drawn from the oil tankers and filled in the storage tanks. The System is
shown below.
Fig.13 Storage Tank Fillers
4. Transfer Pumps
There are two types of transfer pumps
I. HFO transfer Pump ( transfers HFO from storage tanks to the Buffer
Tanks)
II. LFO transfer Pump (transfers LFO from storage Pump to the LFO day
tank
The Basic purpose of these pumps is to take the fuel from the primary storage to the
secondary storage where they can be processed or stored again to be fed to the engines.

17. Kohinoor Energy Limited
Fig.14 Fuel Transfer Pump
5. HFO buffer Tanks
HFO buffer tanks are the secondary storages of HFO. They are in the
engine yard side of the plant. Transfer pump fed the fuel to buffer tanks and from
buffer tanks the fuel is fed to the purification unit.
6. Purification Plant
Purification Plant purifies the HFO before its fed to the engines. It
takes fuel from the buffer tanks and its output fuel is stored into the day tanks.
7. Day tanks
Day tanks are separately available for HFO and LFO. This is the last
entity in the fuel system where purified fuel is stored and this is where from HFO
or LFO is fed to the boosting system and then to generator.
Fig.15 HMI screenshot of fuel system

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BoosterSystem
Booster system is the system that pressurizes and heats the fuel before it
enters the generator. HFO/LFO from their respective day tanks are fed to the booster system
before they are fed to the generator. The input fuel is at room temperature and pressure but
output fuel is at 7.7 bar and 94 Celsius.
Fig.16 HMI screenshot of Booster System
Cooling system
Cooling system is designed to keep the temperature of the generator at a
specified level. There are six cooling towers for the generators and three for the turbine. The
generator cooling system has three parts:
i. Cooling tower
ii. LT Fluid
iii. HT Fluid
The way it works is that the cooling towers cools the LT fluid and that LT fluid is used
to colleen the HT or High temperature fluid that is basically the fluid that runs in the
generator to keep its temperature lower enough to operate properly. The normal
temperature of working is 84 degree Celsius and there is not much temperature boosting
while running of the so all this system has to do is lessen the temperature of the
generators to like 5 to ten degrees. The HMI screenshot at next page explains it all along
with the temperature levels of each side mentioned along.

19. Kohinoor Energy Limited
Fig.17 HMI screenshot of generator cooling system