“OPERATION & MAINTANANCE OF

ADANI THERMAL POWER PLANT MUNDRA”

Summer Internship Report

Submitted in Partial Fulfillment of the Requirements for the Degree

Of

Bachelor of Technology
In
Electrical Engineering
Submitted By:
Prince Bhikadiya
(U21EE064)

Department of Electrical Engineering

SVNIT, Surat
Surat, Gujarat-395007
June - 2024
 Acknowledgment
My 4-week internship at Adani power Limited-Mundra in the operation &
Maintenance department of the Adani Thermal Power Plant has been a
profoundly enriching experience, and I owe s great deal of gratitude to many who
supported me throughout this journey
Firstly I extend my deepest thanks to Mr. Sanjay Patel , Mr. Avinashkumar Singh,
Mr Krunal Chauhan, Mr. RN Rathwa, Mr. Asif Ekbal. Their expert guidance and
unwavering support have been crucial in helping me navigate the complexities of
thermal power operation and maintenance
I am also immensely grateful to all members of the Operation & Maintenance
department. Their dedication to excellence and willingness to share their
knowledge have greatly enhanced my learning experience
Finally I would like to acknowledge the efficient management and administration
at Adani Power Limited. Their effort in creating a conducive learning have not
unnoticed and are greatly appreciated.
This internship has been milestone in my career development and I am thankful
to everyone who played a part in making it successful memorable experience
 Abstract
Embarking on an enriching internship journey, I immersed myself in the intricate
workings of the Adani Thermal Power Plant, a pivotal infrastructure dedicated to
converting thermal energy into electrical power through a systematic process.
This comprehensive report meticulously examines every facet of the plant, from
the essential components like the boiler, turbine, and generator to the myriad
auxiliary systems that ensure seamless operations.
At the heart of the plant's operation lies the combustion of fossil fuels, generating
high-temperature, high- pressure steam that drives the turbine. This mechanical
energy is harnessed to power the generator, ultimately producing the electricity
that powers industries and homes alike. Recognizing the critical role of thermal
power plants in meeting energy demands, the report underscores the importance
of effective maintenance and environmental stewardship practices.
Moreover, amidst global imperatives for sustainability, technological
advancements have ushered in cleaner and more efficient methods of thermal
power generation. These advancements not only mitigate environmental impact
but also pave the way for a more sustainable energy landscape. Through hands-
on experience and insightful learning, this internship provided invaluable insights
into the operational intricacies and maintenance protocols of the Adani Power
Plant, contributing to a deeper understanding of stable and sustainable energy
provision.
 List Of Contant
CHAPTER 1 : INTRODUCTION OD ADANI GROUP ....................................................................... 7
1.1 INTRODUCTION ........................................................................................................................ 7
1.2 ADANI POWER MUNDRA ........................................................................................................ 8
CHAPTER – 2 SAFETY ........................................................................................................................ 9
2.1 OCCUPATIONAL HELATH AND SAFETY .............................................................................. 9
2.2 PERSINAL PROTECTIVE EQUIPMENT (PPE) ........................................................................ 9
2.2 CONFINED SPACE (CS) ........................................................................................................... 10
2.4 MATERIAL SAFETY DATA SHEET(MSDS)........................................................................... 10
2.5 FIRE EXTINGUISHERS ........................................................................................................... 11
2.6 HIGHT WORK ........................................................................................................................... 11
2.7 LOCKOUT/TAGOUT ................................................................................................................ 12
CHAPTER – 3 INTRODUCTION OF THERMAL POWER PLANT ................................................ 13
3.1 INTRODUCTION ...................................................................................................................... 13
3.2 ADVANTAGES & DISADVANTAGES .................................................................................... 13
3.3 PROCESS OF ADANI THERMAL POWER PLANT............................................................... 14
CHAPTER 4 BOILER & OTHER AUXILIARIES ............................................................................. 16
4.1 INTRODUCTION OF BOILER ................................................................................................. 16
4.2 ESSENTIAL QUALITIES OF A GOOD BOILER .................................................................... 16
4.3 CLASSIFICATION OF BOILERS ............................................................................................. 16
4.3.1 SUB CRITICAL WATER TUBE BOILER.............................................................................. 17
4.3.2 SUPER CRITICAL BOILER .................................................................................................. 18
4.4 OTHER AUXILARY OF THE BOILER .................................................................................... 18
4.4.1 COAL MILL ........................................................................................................................ 19
4.4.2 INDUCED DRAFT FAN (ID FAN) .................................................................................... 19
4.4.3 FORCED DRAFT FAN (FD FAN) ...................................................................................... 20
4.4.4 ECONOMIZER ................................................................................................................... 20
4.4.4 ELECTROSTATIC PRECIPITATOR .................................................................................. 21
4.4.5 CONSTRUCTION OF ESP ................................................................................................. 21
4.4.5.1 TRANSFORMER RECTIFIER ........................................................................................ 21
4.4.5.2 CHARGING PLATESO/RODE ....................................................................................... 21
4.4.5.3 COLLECTING PLATES .................................................................................................. 22
4.4.5.4 RAPING MOTOR ............................................................................................................ 22
4.4.5.6 WORKING OF ESP ............................................................................................................. 22
CHAPTER-5 TURBINE & AUXILIARIES......................................................................................... 24
5.1 INTRODUCTION ...................................................................................................................... 24
5.2 WORKING OF TURBINE ......................................................................................................... 24
 5.2.1 Steam Generator:.................................................................................................................. 24
5.2.2 Steam Inlet ........................................................................................................................... 25
5.2.3 Nozzles and Expansion ........................................................................................................ 25
5.2.4 High pressure & low pressure .............................................................................................. 25
5.2.5 Rotor blades ......................................................................................................................... 25
5.2.6 Rotation and Mechanical Work ............................................................................................ 25
5.2.7 Shaft and Power Output ....................................................................................................... 26
5.3 CONDENSER............................................................................................................................. 26
5.4 WORKING OF CONDENSER .................................................................................................. 26
CHAPTER-6 GENERATOR & AUXILIARIES .................................................................................. 28
6.1 INTRODUCTION ...................................................................................................................... 28
6.2 COMPONENTS OF GENERATOR ........................................................................................... 28
6.3 GENERATOR PROTECTION ............................................................................................... 29
6.4 GENERATOR PROTECTION-VARIOUS FUNCTIONS ......................................................... 30
6.5 SPECIFICATION OF THE GENERATOR IN ADANI 660 MW PLANT ................................ 31
6.6 Generator Protection Scheme...................................................................................................... 31
6.6.1 Generator Differential Protection (87 G) ............................................................................. 32
6.6.2 Generator-Transformer Differential Protection (87T).......................................................... 32
6.6.3 Generator overloads protection (51G) ................................................................................. 32
6.6.4 Phase to phase short circuit protection (21G) ...................................................................... 33
6.6.3 Voltage Controlled Overcurrent Protection (51V): .............................................................. 33
6.6.4 Third Harmonic Overcurrent Protection for Stator Earth Fault (64G2): .............................. 33
6.7 GENERATOR EXCITATION SYSTEM .................................................................................... 34
CHATPTER-7 SWITCHYARD ............................................................................................................ 35
7.1 INTRODUCTION TO SWITCHYARD ..................................................................................... 35
7.2 ANALYSIS OF SWITCHYARD SCHEMES AT ADANI.......................................................... 36
7.3.1 ONE AND HALF CIRCUIT BREAKER SCHEME: .............................................................. 36
7.3.2 DOUBLE MAIN BUS & TRANSFER BUS SYSTEM .......................................................... 38
7.4 SWITCHYARD EQUIPMENTS ................................................................................................ 39
7.4.1 Switchyard Equipment ......................................................................................................... 40
7.4.2 Capacitive voltage transformer (CVT): ................................................................................... 40
7.4.3 Wave Trap: ........................................................................................................................... 41
7.4.4 Isolator: ................................................................................................................................ 41
7.4.5 Circuit Breaker (SF6): ........................................................................................................ 42
7.4.6 Current Transformer (CT): ................................................................................................... 43
7.4.7 Inter Connecting Transformer (ICT) .................................................................................... 44
7.4.8 Reactor ................................................................................................................................ 45
 7.4.9 Gas Insulated Substation(GIS) ............................................................................................. 45
7.5 TRANSFORMERS ..................................................................................................................... 46
7.5.1 Generator Transformer (GT) ................................................................................................ 46
7.5.2 Unit auxiliary Transformer (UAT) ....................................................................................... 47
7.5.3 STATION TRANSFORMER ............................................................................................... 48
CHAPTER -8 TESTING INSTRUMENT ............................................................................................ 50
8.1 DIFFERENT TESTING KITS .................................................................................................... 50
8.1.1 Contact Resistance Meter..................................................................................................... 50
8.1.2 Circuit Breaker Time Interval Meter .................................................................................... 50
8.1.3 Secondary injection kit (Omicron) ....................................................................................... 51
CHAPTER-9 BALANCE OF PLANT ................................................................................................. 52
9.1 INTRODUCTION ...................................................................................................................... 52
9.1.1 Functions .............................................................................................................................. 52
9.2 DM & RO PLANT...................................................................................................................... 53
9.1 COLLING TOWER .................................................................................................................... 56
CHAPTER-10 COAL HEANDLING PLANT ................................................................................. 57
10.1 PROCESS OF COAL HANDLING PLANT............................................................................ 57
 CHAPTER 1 : INTRODUCTION OD ADANI GROUP

1.1 INTRODUCTION
Adani Group is a diversified organisation in India comprising 10 publicly traded
companies. It has created a world class transport and utility infrastructure
portfolio that has a pan-India presence. Adani Group is headquartered in
Ahmedabad, in the state of Gujarat, India. Over the years, Adani Group has
positioned itself to be the market leader in its transport logistics and energy utility
portfolio businesses focusing on large scale infrastructure development in India
with O & M practices benchmarked to global standards.

Adani owes its success and leadership position to its core philosophy of 'Nation
Building' driven by 'Growth with Goodness' - a guiding principle for sustainable
growth. Our vision is to be a world class leader in businesses that enrich lives and
contribute to nations in building infrastructure through sustainable value creation

Fig 1.1 Companies own by Adani group

1.2 ADANI POWER MUNDRA

Adani Power Limited is the largest privet thermal power producer

in india with an installed capacity of 15250 MW . Our nine Power are spread
out across the states of Gujrat, Maharashtra, Rajasthan, Karnataka,
Chhattisgarh, Madhya Pradesh, and Jharkhand.
Adani Power created history by synchronizing the first super-critical technology
based 660MW generating unit at Mundra.
The Mundra power project is also the fastest project implementation ever by
any power developer in the country with a record completion of inception to
synchronization within 36 months. Phase III of the Mundra Project, which is
based on supercritical technology, has received "Clean Development
Mechanism (CDM) Project' certification from United Nations Framework
Convention on Climate Change (UNFCCC). This is the world's first thermal
project based on supercritical technology to get registered as a CDM Project
under UNFCCC.
Adani Power Mundra has total capacity of 4620MW. It has total 4 Phases & 9
Units. Phase-1 has 2 units Unit-1 & Unit-2 of 330MW, which is "sub-critical".
Phase-2 has 2 units Unit-3 & Unit-4 of 330MW, which is also "sub-critical".
Phase-3 has 2 units Unit-5 & Unit-6 of 660MW, which is "super-critical".
Phase-4 has 3 units Unit-5, Unit-6 & Unit-7 of 660MW, which is also "Super-
critical".
 CHAPTER – 2 SAFETY

2.1 OCCUPATIONAL HELATH AND SAFETY

At adani , firmly believe that Occupational Health & Safety (OHS) is an
integral part of our activities , Policies , processes and business operations and
are committed to provide safe and healthy workplace across our operating
locations, to our employees, relevant stakeholders, and nearby communities to
achieve our OHS vision “To be globally admire OH&S Leader in the
infrastructure space”.

2.2 PERSINAL PROTECTIVE EQUIPMENT (PPE)

Personal protective equipment (PPE) is protective clothing, helmets,
goggles, other garments equipment designed to protect the wearer’s body from
injury or infection. The hazards addressed by protective equipment include
physical, electrical, heat, chemicals, biohazards, and airborne particulate matter.
Protective equipment may be worn for job- related occupational safety and health.

Fig 2.1 Personal Protective Equipment

2.2 CONFINED SPACE (CS)
The contractor shall: Confirm with site engineer about working in confined
spaces and follow site specific confined space entry procedure if any.

Prepare safe entry procedure and obtain entry and work permits. Provide on the
job training to persons entering confined spaces and have stand-by person and
rescue team for any incidents. Ensure proper ventilation (forced or exhaust).
illumination using 24 v power supply.

Carry out checks for presence of toxic/flammable gases, monitor the oxygen
contentin confined spaces and ensure availability of communication media
between stand-by confined spaces attendant and people inside confined spaces.
Ensure availability of self-contained breathing apparatus or equivalent and use of
all relevant personal protective equipment as per JSA and PTW.

Ensure that all persons exit from the confined space upon completion of the work.
To ensure such exit, head count of the men entering and exiting such confirm
spaces shall be performed and a record maintained in a register.

Fig 2.2 Confined space

2.4 MATERIAL SAFETY DATA SHEET(MSDS)

A Material Safety Data Sheet (MSDS) is a document that contains information
on the potentialhazards (health, fire, reactivity and environmental) and how to
work safely with the chemical product. It is an essential starting point for the
development of a complete health and safety program.
2.5 FIRE EXTINGUISHERS
A fire extinguisher is a handheld active fire protection device usually filled with
a dry or wet chemical used to extinguish or control small fires, often in
emergencies

Fig 2.3 Fire Extinguisher

2.6 HIGHT WORK

Height works above one point eight (1.8) meters have safe access,
egress, and safe platform. Otherwise, people shall be secured through use of full
body harness with double lanyard including shock absorber and sufficient
strengthened lifeline support.
Working platform shall have handrail, mid rail, and toe board. Certified horizontal
lifeline shall be used, preferably 8mm wire rope. Working at more than five (5)
meters (e.g. Transmission tower, truck covering etc.), or requiring different body
posture even at lesser height shall require "fall arrestor" (for vertical movement).
Falling objects safety net shall be installed to arrest such objects. Step
ladder/platform should be used if any personnel intend to work at height. Use of
empty drams to climb up is banned. People taking tools for working at height
shall have tool kits to facilitate three (3) point contact during access and egress.
2.7 LOCKOUT/TAGOUT
Lockout/tagout (LOTO) refers to the specific practices and procedures for
safely de-energizing and re-energizing equipment when service or maintenance
must be performed. Designated workers are required to go through a set of
safety precautions that assure the machine will not inadvertently cause harm to
the individuals servicing the machine.
Proper lockout/tagout (LOTO) procedures save workers from severe
injuries and death. If equipment start up during maintenance, workers can be
caught in the machinery and suffer electrocutions, fractures , lacerations,
crushing injuries amputations, or fatalities.

Fig 2.4 LOGOUT/TAGOUT

 CHAPTER – 3 INTRODUCTION OF THERMAL
POWER PLANT

3.1 INTRODUCTION
Thermal energy is the major source of power generation in India.
More than 60% of electric power is produced by steam plants in India. India has
large deposit of coal (about 170 billion tonnes), 5th largest in world. In thermal
power plants, the heat of combustion of coal is utilised by the boilers to raise
steam at high pressure and temperature. The steam so produced is used in driving
the steam turbines couples to generators and thus in generating electrical energy.
Steam power plants may be installed either to generate electrical energy only or
generate electrical energy along with generation of steam for industrial purposes
such as in paper mills, textile mills, sugar mills and refineries, chemical works,
plastic manufacture, food manufacture etc. The steam for process purposes is
extracted from a certain section of turbine and the remaining steam is allowed to
expand in the turbine. Alternatively, the exhaust steam may be used for process
purposes.

3.2 ADVANTAGES & DISADVANTAGES

ADVANTAGES
• The fuel (i.e., coal) used is quite cheap.
• Less initial cost as compared to other generating stations.
• It can be installed at any place irrespective of the existence of coal. The
coal can be trans- ported to the site of the plant by rail or road.
• It requires less space as compared to the hydroelectric power station.
• The cost of generation is lesser than that of the diesel power station.
 DISADVANTAGES
• It pollutes the atmosphere due to the production of large amount of smoke
and fumes
• It is costlier in running cost as compared to hydroelectric plant

3.3 PROCESS OF ADANI THERMAL POWER PLANT

Here, the Fig simple block diagram of the thermal power plant is showed.
We will see in detail, how the power is generated in thermal power plant from
coal to 22 kilovolts (Output Voltage). And we will also switchyard scheme of
power plant and equipment used for protection in power plant.
First, coal comes from jetty to coal storage by conveyor. Pulveriser pulverise coal
into small pieces around 50mm. and pulverised coal with hot air will transfer into
boiler as fuel. Generally, "Water tube boiler" are used in power plant. Water will
flow into boiler's tube and water will convert into Heat. Heat will again heated by
That superheat will transfer into turbines.
superheater. There are three level turbines, High Pressure turbine, Intermediate
Pressure Turbine and Low- Pressure Turbine. Low Pressure Turbine is connected
with generator. Superheat will flow into High Pressure Turbine and then passes
into Low Pressure Turbine and turbine will rotate and Generator will also rotate.
This is how we generate voltage from generator.

Fig 3.1 Block Diagram Of Thermal Power Plant

After the coal burns, coal will convert into ash. That Ash will be collected by Ash
Handling Plant. Electrostatic Precipitator will collect ash from boiler and Hot air
will be transferred into Environment.
Superheat will then transfer to the condenser. In condenser, air will convert
into water and that water will again use to make heat. This is how thermal power
plant works. We will see in detail how actually power plant works and how all
equipment controlled in power plant. And we will see further from where they all
equipment's receive power.
 CHAPTER 4 BOILER & OTHER AUXILIARIES

4.1 INTRODUCTION OF BOILER

A Boiler is a device used for generating steam from water or other

liquids. This steam is utilized for power generation, for process heating or for
space heating. Sometimes only hot water is produced in a boiler and utilized for
heating purpose.
The capacity of the boiler used for power generation is considerably large. The
steam is also produced at high pressure due to requirement of the efficiency.

4.2 ESSENTIAL QUALITIES OF A GOOD BOILER

• A good boiler should have the following qualities:

• It should produce maximum steam with minimum fuel consumption, i.e. it
should have higher efficiency
• It should be able is deliver desired quantity of steam quickly after starting.
• It should be able to meet large load fluctuations.
• It should be easy to maintain and inspect.
• It should occupy less space.

4.3 CLASSIFICATION OF BOILERS

Boiler mat be classified as

1. Fire tube boiler:- in this type of boiler, hot gases pass through tubes which
are surrounded with water. The Cochran , locomotive and lancasbire boiler
are fire tube boiler

2. Water-tube boiler:- water tube boiler is one of the type of boiler where
the water is feed and circulated in metallic tube called water tube to heat
the water and generate steam, the water tubes are surrounded by fire. The
 water tube boiler can be used up to a pressure level of 250 bars. The
construction of water tube boiler is shown below

• Various type of water tube boiler

1. Sub critical Boiler
2. Super critical Boiler

4.3.1 SUB CRITICAL WATER TUBE BOILER

Subcritical boilers are crucial components in thermal power plants due to
their role in generating steam to drive turbines and produce electricity. These
boilers operate below the critical point of water, ensuring efficient heat transfer
and stable performance. They are cost- effective and widely used, contributing
significantly to power generation worldwide. Their importance lies in their ability
to convert thermal energy into mechanical energy, making them indispensable in
the functioning of thermal power plants and meeting the ever-increasing global
demand for electricity.

Fig 4.1 Sub Critical Boiler

4.3.2 SUPER CRITICAL BOILER
The thermal efficiency of the power plant can be improved by using the
steam at super critical condition. This paper mainly studies the general concept
of the super critical boiler and discuss its merits and demerits. The improvement
in overall efficiency of the plant will be at least 2% if the super critical parameters
are implemented. The importance of thermal efficiency of the thermodynamic
cycle and the methods to improve the thermal efficiency of the cycle are also
analyzed.
Therefore, attention is focused on improving the thermal efficiency of the steam
power cycle. We can improve the plant efficiency by using the steam at
supercritical condition. The supercritical parameters of the plant improve upon
the efficiency of the plant compared to sub critical parameters by at least 2% the
dry steam state.

Fig 4.2 Super Critical Boiler

4.4 OTHER AUXILARY OF THE BOILER

Numerous auxiliary components, including the coal feeder, coal mill, induced
draft fan, forced draft fan, primary air fan, economizer, superheater, air preheater,
deaerator, condenser, draft fans (both forced and induced), blowdown tank, fuel
feed system, and ash handling system, are integral to the boiler system. These
components enhance the efficiency, safety, and operational stability of the system.
Below is a detailed explanation of these crucial auxiliaries and their roles within
the system.

4.4.1 COAL MILL

The coal feeder facilitates the transfer of coal from the storage bunker to
the pulveriser, adjusting the flow based on operational demands. It features plates
that direct the coal flow, thereby protecting the conveyor belt from the direct
impact of incoming feed. This component is crucial for maintaining a consistent
and controlled supply of coal, ensuring the boiler operates at optimal efficiency.
Additionally, it plays a vital role in minimizing wear and tear on the conveyor
system, extending the lifespan of the machinery involved. Below, we present
some fundamental details about the coal feeder.

Fig 4.3 Coal Mill

4.4.2 INDUCED DRAFT FAN (ID FAN)

An Induced Draft Fan (ID Fan) in a thermal power plant is a crucial

component designed to maintain proper air flow within the boiler system.
Positioned at the exit of the boiler and before the flue gas cleaning system, the ID
fan creates a negative pressure or suction which pulls flue gases through the
boiler, aids in maintaining the desired air/fuel ratio, and ensures complete
combustion of the fuel. This fan is essential for the regulation of air flow, pressure
at the furnace exit, and the efficient operation of the waste heat recovery system.
 The ID fan operates by drawing heated air and flue gases from the boiler
and expelling them to the atmosphere after pollution control measures. This
process not only assists in the efficient burning of fuel but also helps in controlling
environmental pollution by ensuring that gases passing through are well-treated
and meet regulatory standards. The fan's ability to control the pressure and
volume of gases ensures that boilers operate at their highest efficiency, reducing
fuel consumption and lowering operational costs. Additionally, the ID fan plays
a pivotal role in system safety by preventing the backflow of toxic gases into the
working area, thus safeguarding plant operations and personnel.

4.4.3 FORCED DRAFT FAN (FD FAN)

In a thermal power plant, the Forced Draft Fan (FD Fan) is an essential
component designed to supply the necessary air required for fuel combustion.
Positioned near the base of the boiler, the FD Fan pushes air into the furnace,
ensuring that the air pressure inside the furnace exceeds the ambient atmospheric
pressure. By doing so, the fan guarantees that the air and fuel mixture is adequate
for efficient combustion. The forced airflow helps in dispersing the fuel particles
evenly, which is critical for maintaining consistent flame stability and effective
heat transfer throughout the boiler.
The operation of the FD Fan involves drawing air from the environment and
forcefully injecting it into the combustion chamber through air preheaters. The
air preheaters are used to increase the temperature of the incoming air by
recovering heat from the flue gases. This preheated air then aids in igniting the
fuel more efficiently, leading to a more complete and cleaner combustion process.
The efficiency of the FD Fan directly impacts the boiler's overall thermal
efficiency and emission levels. Moreover, the fan's capacity and speed are
typically controlled according to the boiler load requirements, ensuring optimal
combustion conditions at varying operational levels.

4.4.4 ECONOMIZER
In a thermal power plant, an economizer is a critical component designed
to increase the efficiency of the boiler by capturing residual heat from the flue
gases that would otherwise be lost to the environment. This recovered heat is then
used to preheat the boiler feedwater, which reduces the energy required to bring
the water up to temperature in the steam generation process. By preheating the
water, the economizer significantly enhances the overall thermal efficiency of the
plant.

4.4.4 ELECTROSTATIC PRECIPITATOR

An Electrostatic Precipitator (ESP) in a thermal power plant is a crucial
device used for controlling air pollution by trapping fly ash particles from the
exhaust gas before they escape into the atmosphere. It operates on the principle
of electrostatic attraction; as the flue gases pass through the ESP, an electric field
charges the ash particles, which are then attracted to oppositely charged collector
plates. These plates collect the particles, and rappers periodically shake them off
into a hopper for disposal, ensuring that clean gas exits the system

4.4.5 CONSTRUCTION OF ESP

The construction of an Electrostatic Precipitator (ESP) in a thermal power
plant involves assembling a series of components designed to effectively remove
particulate matter from flue gases. This system typically includes discharge
electrodes, which generate the necessary electric field, and collector plates that
attract and capture the charged particles. Housed within a large metal frame, the
ESP also incorporates rappers or vibrators to periodically dislodge accumulated
ash from the plates, which is then collected in hoppers located at the bottom.
Robust insulators are used to prevent current leakage, ensuring efficient
operation.

4.4.5.1 TRANSFORMER RECTIFIER

It converts the alternating current (AC) input into a high-voltage direct
current (DC) output, which is necessary for the ESP to function effectively. The
high voltage from the TR unit charges the dust
particles in the flue gases, making them adhere to the
collection plates of the ESP

4.4.5.2 CHARGING PLATESO/RODE

Charging plats in an Electrostatic precipitator
Are used to ionize the particales present in the
Exhaust gas steam These plates are charged with a
High voltage creating strong electric field between
Them and the grounded collection plates.
4.4.5.3 COLLECTING PLATES
The charged particles are then attracted to the oppositely charged collection
plates. Since the plates are positively charged, they attract the negatively charged
particles, causing them to stick to the plates from the gas stream.

4.4.5.4 RAPING MOTOR

Rapping motors are specialized device used in electrostatic precipitators in
thermal power plant to dislodge accumulated particulates matter from the
collection plates and electrodes. These motor ensure that the ESP operates
efficiently by periodically removing the ash and dust that can hinder its
performance

4.4.5.6 WORKING OF ESP

The working principle of the electrostatic precipitator is quite simple. It has
two sets of electrodes one is positive, and another is negative called charging plate
and collecting plates.
The negative electrodes are in the form of a rod or wire mesh. Positive
electrodes are in the form of plates. The positive plates and negative electrodes
are placed vertically in the electrostatic precipitator alternatively one after
another.
The negative electrodes are connected to a negative terminal of a high
voltage DC source, and positive plates are connected to the positive terminal of
the DC source. The positive terminal of the DC source may be grounded to get
stronger negativity in the negative electrodes.
The distance between Each negative electrode and positive plate and the
DC voltage applied across them are so adjusted that the voltage gradient between
each negative electrode and adjacent positive plate becomes quite high to ionize
the medium between these.
The medium between the electrodes is air, and due to the high negativity
of negative electrodes, there may be a corona discharge surround the negative
electrode rods or wire mesh
The air molecules in the field between the electrodes become ionized, and
hence there will be plenty of free electrons and ions in the space. The entire
system is enclosed by a metallic container on which one side is provided with an
inlet of the flue gases, and the opposite side is provided with the outlet of the
filtered gases.
As soon as the flue gases enter the electrostatic precipitator, dust particles in the
gases collide with the free electrons available in the medium between the
electrodes and the free electrons will be attached to the dust particles.
As a result, the dust particles become negatively charged. Then these
negatively charged particles will be attracted due to the electrostatic force of the
positive plates. Consequently, the charged dust particles move towards the
positive plates and deposit on positive plates.
Here, the extra electron from the dust particles will be removed on positive
plates, and the particles then hammer hammers to the collecting plates at every
10 seconds. And all the Ash will collect in collecting hopper.
The flue gases after traveling through the electrostatic precipitator become
almost free from ash particles and ultimately get discharged to the atmosphere
through the chimney.
 CHAPTER-5 TURBINE & AUXILIARIES

5.1 INTRODUCTION

When steam become super heat it then passes into turbine. The worling of a steam
turbine involves the conversion of thermal energy from pressurized steam into
mechenical work, which can be used to generate electricity or drive various
mechenical processes. Steam turbines are commonly used in power plant and
other industrial application due to their efficiecy and relaiblities. Here’s a step by
step explanation of how a stem turbine works:

5.2 WORKING OF TURBINE

5.2.1 Steam Generator:

The process beings with generation of steam. This is typically achieved by
heating water in a boiler until it reaches a high temperature and pressure. The high
pressure steam is then ready to be sent to the turbine.

Fig 5.1 Steam Generator

5.2.2 Steam Inlet
The high-pressure steam is directed into the steam turbine through a system
of pipes and valves. It enters the turbine at a specific pressure and temperature,
depending on the design and requirements of the turbine and the power plant.

5.2.3 Nozzles and Expansion

Inside the turbine, the high pressure steam encounter a series of nozzles or
fixed blades known as a nozzle box are strategically designed to accelerate the
steam to a high velocity as it exist. This high velocity steam is directed onto the
moving blades of the turbine rotor.

5.2.4 High pressure & low pressure

Steam turbines can be categorized into High Pressure turbines and Low
Pressure turbines, or a combination of both. In High Pressure turbines, the high-
velocity steam from the nozzles impacts the rotor blades, causing them to move.
The pressure of the steam remains relatively constant as it undergoes an
expansion process. In Low Pressure turbines, the steam expands continuously
across both stationary and moving blades, resulting in a combination of pressure
and kinetic energy being converted into mechanical work. These turbines are
designed for high-flow.

5.2.5 Rotor blades

The rotor of the steam turbine consists of a set of blades mounted on a

shaft. These blades are shaped to capture the energy from the high velocity steam
and convert it into rotational motion

5.2.6 Rotation and Mechanical Work

As the high-velocity steam flows over the rotor blades, it exerts a force on
them, causing the rotor to rotate. This rotation of the rotor generates mechanical
work in the form of rotational kinetic energy..
5.2.7 Shaft and Power Output

The shaft connected to rotor transfers the the mechanical energy to the
desired mechanical load or a generator. In power plants, the rotating shaft is
connected to an electric generator, which converts the mechanical energy into
electrical energy.

5.3 CONDENSER

A condenser is an auxiliary device in a

power plant that plays a crucial role in the
conversion of steam into electrical energy. It is a
type of heat exchanger that transfers heat from the
steam to the cooling medium, which is usually
water. Its primary function is to convert steam
that has passed through the turbines back into
water for reuse in the boiler, improving overall
efficiency and conserving water.

5.4 WORKING OF CONDENSER

condenser is designed to transfer heat from a working fluid (e.g. water in a

steam power plant) to a secondary fluid or the surrounding air. The condenser
relies on the efficient heat transfer that occurs during phase changes, in this case
during the condensation of a vapor into a liquid. The vapor typically enters the
condenser at a temperature above that of the secondary fluid. As the vapor cools,
it reaches the saturation temperature, condenses into liquid and releases large
quantities of latent heat. As this process occurs along the condenser, the quantity
of vapor decreases and the quantity of liquid increases; at the outlet of the
condenser, only liquid remains. Some condenser designs contain an additional
length to sub-cool this condensed liquid below the saturation temperature.

Fig 5.2 working of Condenser

 CHAPTER-6 GENERATOR & AUXILIARIES

6.1 INTRODUCTION
In thermal power plants, the generator serves as a critical component for
converting mechanical energy, primarily derived from steam-driven turbine
motion, into electrical energy. This transformation is achieved through the
principle of electromagnetic induction. The type of generator most commonly
used in these facilities is the synchronous generator. This choice is due to its
ability to maintain a consistent speed and phase with the electrical grid, ensuring
a stable and continuous supply of electricity. Synchronous generators in thermal
power plants are essential for efficient power production and distribution,
highlighting their significance in the energy sector.

6.2 COMPONENTS OF GENERATOR

Rotor (Armature): The rotor, an essential rotating component within the

generator, features a central shaft surrounded by conductors wrapped in insulated
coils. This design facilitates the interaction with the magnetic field during
rotation. As the rotor moves, it disrupts the magnetic field lines emanating from
the stator, thereby inducing an electromotive force (EMF). The materials and
configuration of the rotor are optimized to maximum electrical conductivity and
mechanical strength.

Stator: Constructed from high permeability silicon steel to reduce hysteresis and
eddy current losses, the stator is a stationary part if the generator. It house copper
or aluminium winding that are insulated to withstand high voltage. These winding
are intricately arranged to from a continuous loop that enhances the magnetic
field necessary for the induction process as the rotor turns within it.

Magnetic Field: In modern generators, the magnetic field is created either

through permanent magnets made from rare-earth materials that provide a
consistent and strong magnetic field or through electromagnets powered by
external sources. This field is crucial for the conversion process from mechanical
to electrical energy, and its stability affects the overall efficiency and output of
the generator.
Air Gap: The air gap, typically maintained within a precise range of 90 mm to
110 mm in large 660MW generators, is crucial for the magnetic coupling between
the rotor and the stator. This space is optimized based on the generator's design
to balance magnetic flux density and minimize losses, directly influencing the
operational efficiency and output power quality.
Excitation: The excitation system comprises a smaller generator that supplies
direct current (DC) to the rotor's field windings. Key components include a
rectifier circuit to convert AC to DC, and an excitation transformer to adjust
voltage levels. This setup is crucial for controlling the strength of the rotor's
magnetic field and, by extension, the output voltage of the main generator.
AVR (Automatic Voltage Regulator): The AVR is a critical component in
managing the generator's output stability. It automatically adjusts the excitation
to the rotor and controls the voltage output by sensing and reacting to changes in
the load conditions. This regulation helps maintain a steady voltage output,
ensuring the generator operates within its optimal electrical parameters and
safeguards against voltage fluctuations that could damage connected equipment.
ROTOR EARTHING: - Rotor earthing is used to earth the rotor current which
will induced in the machine

6.3 GENERATOR PROTECTION

Generator protection is a critical aspect of electrical engineering that

involves safeguarding generators from damage and ensuring their efficient
operation within power systems. The protection mechanisms are designed to
detect faults, prevent mechanical and thermal damage, and manage operational
loads effectively. This is essential not only for maintaining the integrity and
longevity of the generator but also for ensuring the stability and reliability of the
entire power grid. Generator protection systems utilize a combination of
advanced sensors, protective relays, and control algorithms to monitor and
respond to various operational parameters, thus preventing failures that could lead
to significant financial and operational setbacks..
6.4 GENERATOR PROTECTION-VARIOUS FUNCTIONS

Generating units are the source of the power system and their security against any
adverse conditions is most important in the system. The generator protection must
ensure a fast and selective detection of any fault in order to minimize their
dangerous effects.

Protection of passive elements like transmission lines and transformers is

relatively simple which involves isolation of faulty element from the system,
whereas protection of generators involves tripping of generator field breaker,
generator breaker and turbine. Generator Protections are broadly classified into
three types.

CLASS-A:- This covers all electrical protections for faults within the generating
unit in which generator field breaker, generator breaker and turbine should be
tripped.

CLASS-B: this covers all mechanical protections of the turbine in which turbine
will be tripped first and following this generator will trip on reverse power/low
forward power protections.

CLASS-C:- This covers electrical protection for faults in the system in which
generator will be unloaded by tripping of generator breaker only. The unit will
come to house load operation and the UAT will be in service. Various protections
of this class are:

i) 220 KV (HV side of Generator Transformer) busbar protection.

Generator Transformer HV side breaker pole discrepancy.
iii) Generator negative phase sequence protection
iv) Generator Transformer over current/Earth fault protection
v) Reverse power protection without turbine trip.
6.5 SPECIFICATION OF THE GENERATOR IN ADANI 660 MW
PLANT

SPECIFICATION VALUE
Apparent power 776.5MVA
MVA Rating 660 MW
Rated voltage 22000 V
Rated current 20377 A
Power Factor 0.85
Number of Phases 3
Frequency 50 Hz
Rated speed 3000 RPM
Insulation Class F
Exciter Voltage 468.21 V
Exciter Current 4476 A
Rated H2 Gas Pressure 0.45 MPa
Cooling Mode H20-H2-H2
Stator Winding Connection YY

6.6 Generator Protection Scheme

Fig 6.1 Generator protection scheme

6.6.1 Generator Differential Protection (87 G)
Generator differential protection, identified as '87G' in electrical
schematics, is pivotal for detecting faults within generator windings by
comparing the currents at the generator's terminals. Utilizing current transformers
(CTs) to measure the incoming and outgoing currents, the '87G' relay ensures they
remain approximately equal under normal conditions, and any significant
discrepancy indicative of a fault prompts immediate isolation of the unit.
However, this system's efficacy can be compromised by CT mismatches, leading
to false trips or non- operation during actual faults. Additionally, the protection
scheme can be complex and costly due to the extensive wiring and additional
CT's required, with potential desensitization issues arising from CT saturation
during external faults or transient events, delaying fault detection.

6.6.2 Generator-Transformer Differential Protection (87T)

This is like Generator Differential Protection, which covers from the
generator terminals up to the HV breaker of generator transformer. Sometimes
this relay is not provided where Generator and Generator Transformer Overall
Differential relay (870) is provided. 87G & 87T functions should have the
features of through fault restraint, magnetizing inrush restraint

6.6.3 Generator overloads protection (51G)

The Generator Overload Protection, denoted as 51G in protection schemes,
is a crucial component that guards the generator against conditions that may cause
it to exceed its rated capacity. This type of protection employs thermal relays or
thermistors that measure the temperature of the generator's windings, typically
calibrated to the generator's thermal capability curve. It operates on a time-
overcurrent principle, where the time for relay activation is inversely proportional
to the magnitude of the current. The relay delays operation for transient overloads
that the generator can withstand, but it will trip the generator if the overload
persists, thereby preventing thermal damage due to sustained excessive current.
6.6.4 Phase to phase short circuit protection (21G)
Phase-to-phase short circuit protection, commonly referred to by the ANSI
device number 21G, is designed to detect and mitigate the effects of short circuits
occurring between two phases of a generator. This protection mechanism works
through the use of current transformers (CTs) that monitor the electrical current
in each phase. When a short circuit between phases occurs, the CT's detect an
abnormal surge in current. The relay then compares the current magnitudes and
angles across the phases, and if the values exceed predefined settings indicative
of a phase-to-phase fault, the relay will trip the circuit breaker, isolating the
affected equipment to prevent further damage.

6.6.3 Voltage Controlled Overcurrent Protection (51V):

Voltage controlled overcurrent protection (51V) is designed to protect
electrical equipment against overloads and short circuits, particularly in scenarios
where system impedance changes, like in distributed power systems. It operates
by monitoring the current with respect to the voltage; thus, it can distinguish
between a heavy load and a fault. When the current exceeds a certain threshold
while the voltage is within a normal range, it suggests an overload condition, and
the relay can trip after a set time delay, providing selective coordination in the
power system.

6.6.4 Third Harmonic Overcurrent Protection for Stator Earth Fault

(64G2):
harmonic overcurrent protection for stator earth fault (64G2) is used to
detect ground faults within a generator's stator winding. It works on the principle
that under normal conditions, the third harmonic content is distributed uniformly,
but in the event of a ground fault near the star point of the generator, this balance
is disturbed. The protection scheme
6.7 GENERATOR EXCITATION SYSTEM
The system which is used for providing the necessary field current to the
rotor winding of the synchronous machine, such type of system is called an
excitation system. In other words. excitation system is defined as the system
which is used to produce the flux by passing current in the field winding. The
main requirement of an excitation system is reliability under all conditions of
service, a simplicity of control, ease of maintenance, stability, and fast transient
response.
The amount of excitation required depends on the load current, load power factor
and speed of the machine. The more excitation is needed in the system when the
load current is large, the speed is less, and the power factor of the system becomes
lagging. The excitation system is mainly classified into three types. They are as
below.

AC Excitation System
1. Brushless Excitation System
2. Static Excitation System

Fig 6.2 Generator Excitation system

 CHATPTER-7 SWITCHYARD

7.1 INTRODUCTION TO SWITCHYARD

The switchyard at Adani Thermal Power Plant in Mundra plays a pivotal

role in the efficient distribution of electricity generated by the plant. It serves as
a critical junction where electrical power is received from the power plant's
generators and then transmitted to the grid at a suitable voltage level. Equipped
with high-voltage switchgear, transformers, and protection devices, the
switchyard ensures the stability and reliability of power transmission. Its design
and operation are central to managing the flow of electricity, highlighting the
integration of advanced engineering solutions in addressing the challenges of
large-scale power distribution.
The switchyard at Adani Thermal Power Plant Mundra is systematically
segmented into four distinct phases to accommodate varying voltage levels for
efficient power distribution. Phases 1 and 2 are designed to handle 200 kV,
catering to specific distribution requirements, while Phases 3 and 4 are upgraded
to manage 400 kV, supporting higher transmission needs. This division reflects
the plant's strategic approach to optimizing the electrical output and ensuring the
reliability of power supply to the grid.

Fig 7.2 Switchyard

 The Adani thermal power plant in Mundra has established a robust
transmission network, ensuring the efficient distribution of electricity across
various regions. This network is meticulously designed to accommodate different
voltage levels, facilitating the transfer of power over both short and long distance.
Below is a concise overview of the transmission lines extending from the plant:

S.No Destination Voltage

1 Nanikhar 1,2 220 kV
2 Tappar 1,2 220 kV
3 MRSS 220 kV
4 Varsana 400 kV
5 Hadala 400 kV
6 Sami-Dehgam 1,2 400 kV
7 Zarda 1,2,3,4 400 kV
8 HVDC 1,2 500 kV

7.2 ANALYSIS OF SWITCHYARD SCHEMES AT ADANI

The switchyard at the Adani Thermal Power Plant is equipped with two
distinct schemes: the One and Half Circuit Breaker Scheme and the Transferred
Bus Scheme. These schemes are utilized in different phases of the power plant's
operation to ensure efficient and reliable power transfer. Phase 1 of the
switchyard utilizes the Transferred Bus Scheme, while phases 2, 3, and 4
employ the One and Half Circuit Breaker Scheme.
Bus Bar arrangement is nothing but a combination of Bus and Circuit Breaker.
Normally in Switchyard, Bus is made of hollow tubular aluminum called IPS
Tubes (here IPS stands for Iron Pipe Size, a code for selection of tubes). Corona
and electrostatic field performance is better for tube bus; therefore Aluminum
Tubes are used for Buses.

7.3.1 ONE AND HALF CIRCUIT BREAKER SCHEME:

In high voltage Switchyard like in 400kv switchyard “one and half
breaker bus system is used due to many advantages of this scheme. The
advantages of this scheme will be discuss later.
In the figure above, CB stands for Circuit Breaker, LA for Lightening Arrestor,
ES for Earth Switch and DS for Disconnect Switch also called Isolator.
In One and Half Breaker Scheme, three breakers are connected between the two
buses. Each Breaker is provided with two Isolators and two Earth Switches. These
Isolators are provided to physically isolate the Circuit Breaker maintenance. for
Earth Switch ES is provided to ensure that isolated portion is effectively earthed.
Earth Switch shall be closed after the opening of Isolator.

Fig 7.2 One and half circuit breaker scheme

breakers is called Diagonal in One and Half Breaker Scheme. In the figure, thus
two Diagonals are shown. A feeder is connected in between the two Breakers
CB-A and CB-C & CB-B and CB-C. Notice that three Breakers are
used in this scheme to protect two Feeders and therefore it is called 3/2 i.e. One
and Half Breaker scheme.
Let us consider some interesting aspects of One and Half Breaker Scheme. Let us
assume a fault in any one feeder say in Feeder-1. In this case protection shall open
the CB-A and CB-C & send Direct Trip signal to the Remote station through
PLCC. to isolate the fault. Mind that even though CB-A and CB-C are open,
Feeder-2 is still in service and fed by Bus-2. Thus One and Half Breaker scheme
increases the reliability of Power System.
Let us assume that, we need to take maintenance of CB-B of Diagonal-1. So we
will open the Breaker CB-B and will isolate it by opening Isolators and closing
Earth Switch ES. Again, notice that none of the feeder will be out of service rather
Feeder-2 will be fed through CB-A and CB-c. The most important advantage of
this scheme is that you can take one Bus out for maintenance without interrupting
power supply in Feeders.
Advantages if One and Half breaker Scheme are as follows.
1) Its high security against loss of power supply to feeders which suitable for
Switchyard associated with generating Stations and quantum of power is handled
through individual circuits. This involves for maintenance.
2) Area requirement is less in this arrangement compared to Two Main and
Transfer Scheme
3) Cost is also less compared to Two Main and Transfer Bus Scheme.
4) Either bus may be taken out any time without loss of service to the feeders.
Maintenance of more than one breaker is possible without any loss of service. In
this system no isolator operation is required for changing over from one bus to
other, as all three breakers remain closed under normal operation.
5) In case of bus fault, power supply to the connected feeders continues from the
other bus with no power interruption required for isolation of the faulty bus. This
advantage is not available with Two Main and Transfer Bus Scheme as in case of
a bus fault all associated breakers will trip resulting in interruption of power
supply to affected feeders. However, failure of center breaker only reduces the
flexibility of uninterrupted changeover of feeders from one bus to the other.

7.3.2 DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

In high voltage switchyards, such as in a 400kV switchyard, the Double
Main Bus and Transfer Bus System is utilized due to its numerous advantages.
This scheme provides a high level of reliability and flexibility in power
distribution.
In the Double Main Bus and Transfer Bus System, there are two main buses (Bus-
1 and Bus- 2) and a transfer bus (T-Bus) connected between them. Each main bus
is connected to the power source through its own circuit breakers, isolators, and
earth switches. The transfer bus is connected to both main buses through isolators
and circuit breakers.

The operation of the Double Main Bus and Transfer Bus System is as follows:
Under normal operating conditions, both main buses are energized and supply
power to their respective loads The transfer bus remains de-energized. If a fault
occurs on one of the main buses, the circuit breakers on that bus trip, isolating it
from the system.
The transfer bus then becomes energized and supplies power to the loads
connected to the faulty bus, ensuring uninterrupted power supply. The isolators
and earth switches are used to isolate and ground the faulty bus for maintenance.

Fig 7.3 Double bus and transfer bus scheme

Advantages of Double Main Bus and Transfer Bus System:

1) High Reliability: The system provides a high level of reliability in power
distribution, as it allows for uninterrupted power supply even in the event of a
fault on one of the main buses.
2) Flexibility: The system offers flexibility in power distribution and allows for
maintenance of one main bus without interrupting power supply to the loads.
3) Cost-effective: The system is cost-effective compared to other schemes, such
as the One and Half Circuit Breaker Scheme, as it requires fewer circuit breakers
and components.
4) Easy Maintenance: The system allows for easy maintenance of individual
buses without interrupting power supply to the loads.
5) Fault Tolerance: The system is fault-tolerant, as it can continue to supply power
even in the event of a fault on one of the main buses.

7.4 SWITCHYARD EQUIPMENTS

The switchyard of Adani Thermal Power Plant Mundra is equipped with
advanced infrastructure designed to ensure efficient transmission and
distribution of electricity. This section highlights the critical switchyard
equipment and their specification, underscoring the plants commitment to
reliability and safety in power distribution.

7.4.1 Lightning Arrester (LA):

In the 400 kV switchyard of Adani Thermal Power Plant, Mundra, the
lightning arrester plays a pivotal role in protecting the electrical equipment from
lightning-induced surges. The technical specifications of the lightning arresters,
including models Y10W-200/520, Y10W-390/900, and Y10W-360/850, are
designed to cater to varying operational voltages and discharge currents.

These arresters ensure the reliability and safety of the switchyard by effectively
controlling the energy and voltage levels induced by lightning strikes and
switching operations

Fig 7.4 lightning arrester

7.4.2 Capacitive voltage transformer (CVT):

Capacitive Voltage Transformer have been widely used within
transmission power system for application ranging from high voltage to ultra high
voltage. CVT are primarily used for voltage measurement, providing voltage
signals to metering units, protection relay devices, and automatic control devices.
CVTs can also used to couple power line carrier technology to the power system
for communication purpose.
The 400kv switchyard employs various capacitive voltage
transformer for different purpose like tariff metering, line
monitoring and interfacing with generator and bus sections.
These CVTs range in capacitance from 4000pF to 8800pf and
are designed to meet specific classification standards for
accuracy and performance such as core2 class 0.5 and
core1&2 for protection purpose. Each CVT model is
carefully selected to ensure precise voltage measurement and
reliable operation under the designated electrical conditions,
supporting the critical function of metering, protection, and
communication within the high voltage environment
Fig 7.5 CVT

7.4.3 Wave Trap:

Wave traps, such as the 400kV, 1600A model made by Areva, are critical
in switchyards for separating high- frequency communication signals from the
standard power frequency (50/60 Hz). Constructed with inductors and capacitors
to form a tuned circuit, they offer low impedance to power frequencies while
providing high impedance to

Fig 7.6 Wave Trap

high-frequency signals. This design ensures that communication signals

are protected and can travel without interference, supporting the essential
functions of metering. protection, and communication within the high-voltage
transmission environment.

7.4.4 Isolator:
The DDK800 Horizontal Knee Type Disconnector, engineered by ABB,
showcases advanced design optimized for reliability and space efficiency in
electrical switchyards. It boasts a high Short Time Current (STC) carrying
capacity of 50 kA for 3 seconds with a peak of 130 kA, and it's rated for a
continuous operation of 3150 A. Notably, it
ensures no corona inception up to 110% of its
rated test voltage, achieving a Radio Influence
Voltage (RIV) significantly below the standard
requirements.

Its construction features two support

insulators, a rotating insulator for operation,
and a main blade accompanied by two arms
for mechanical movement, ensuring balanced
Fig 7.7 Isolator

forces and simplified maintenance. This disconnector is tailored for long-

term service, demonstrating ABB's commitment to combining technical
excellence with practical deployment in high- voltage switchyard

7.4.5 Circuit Breaker (SF6):

Circuit breakers are crucial components in
switchyards of power plants. They serve as
switches that can interrupt the flow of electricity
in the event of a fault or overload, thereby
protecting the electrical system from damage.
Circuit breakers play a vital role in ensuring the
safety and reliability of the power supply by
isolating faulty sections of the system and
maintaining the integrity of the rest of the
network. Fig 7.8 Circuit Breaker

Circuit breakers in switchyards are designed to operate under various conditions,

including normal operating conditions, fault conditions, and maintenance
conditions. Under normal operating conditions, circuit breakers are closed and
allow the flow of electricity through the system. In the event of a fault, such as a
short circuit or overload, the circuit breaker automatically opens to isolate the
faulty section of the system and prevent damage. During maintenance, circuit
breakers may be opened manually to allow for inspection, repair, or replacement
of components.
The circuit breakers used in the switchyard of the Adani Thermal Power Plant are
of the LW25-420 (SF6) type, with a rated voltage of 420 kV and a rated current
of 2500 A. These circuit breakers are designed to withstand a rated LI voltage of
1425 kV and an operating impulse withstand voltage of 1050 kV. They have a
rated short-circuit breaking current of 50 kA and a rated line charged breaking
current of 400 kA. The closing and opening coil voltage is rated at 220 V DC,
and the operating sequence includes 0-0.3s-CO-180s-CO for various operations.
The circuit breakers are manufactured by Chaina XD and are part of groups
designed for specific bays and sections within the switchyard.

7.4.6 Current Transformer (CT):

Current Transformers (CTs) are essential components in switchyards. They
are used to measure electrical current in high voltage circuits and provide a
proportional current in its secondary winding, which is suitable for measurement
or protection purposes. CTs play a crucial role in monitoring and controlling the
flow of electricity in the switchyard, ensuring the safety and efficiency of the
electrical system.
CTs are primarily used for metering, protection, and control purposes in
switchyards. They accurately measure the current flowing through the primary
circuit and provide a scaled-down current in the secondary winding. This current
is then used to operate protective relays, meter

Fig 7.9 CT

s, and other control devices. CTs are essential for ensuring that the electrical
system operates within safe limits and for detecting and isolating faults to prevent
damage to equipment and ensure the continuity of power supply.
The CTs used in the switchyard of the Adani Thermal Power Plant are of the
LVQHB-500W2 type, manufactured by
7.4.7 Inter Connecting Transformer (ICT)
The Interconnected Transformer (ICT) in the switchyard serves a pivotal
role in linking the 200kV bus with the 440kV bus, ensuring efficient power
transmission across different voltage levels. This crucial piece of equipment not
only facilitates the seamless flow of electricity but also enhances the reliability
and flexibility of the grid. Its sophisticated cooling mechanisms-
ONAN/ONAF/OFAF-adapt to varying load demands, maintaining optimal
performance and longevity.

Fig 7.10 Interconnected Transformer

The ICT's specifications are tailored to robust operational requirements, with

ratings that accommodate a wide range of loads: 189/252/315 MVA for HV & IV
under 60%, 80%, and 100% loads, respectively, and 63/84/105 MVA for LV.
These ratings, alongside its high- capacity line currents and substantial oil and
total weight, underscore its capability to handle massive power flows while
sustaining a 50°C temperature rise over the ambient temperature, ensuring
operational integrity.
Key features such as its no-load voltages of 400kV, 220kV, and 33kV for HV, IV,
and LV. respectively, and line currents tailored for each voltage level, further
highlight the transformer's design to efficiently manage power distribution. The
ICT's design and specifications reflect a meticulous balance between
performance safety and durability making it as an essential component of the
switchyard of the switchyard infrastructure.
7.4.8 Reactor
Bus reactors, integral components of switchyards, are designed to stabilize
the power grid by controlling voltage fluctuations and managing short-circuit
currents. They are pivotal in ensuring that electrical energy distribution is both
efficient and safe, particularly in systems with high transmission voltages
The reactors are strategically operated based on load demands within the grid.
They are typically activated during periods of high electrical load to absorb
excess power, preventing potential overvoltage that could harm the network or
connected equipment. Conversely, to maintain voltage stability during low
demand, reactors are often deactivated, showcasing their role in adapting to and
moderating the grid's dynamic conditions.

Fig 7.11 Reactor

The reactors in the switchyard, designated as Reactor-1, Reactor-2, and Reactor-

3, are crucial components manufactured by Baoding Transformer Co. Ltd.
Reactor-1 and Reactor-2, each with a rated capacity of 27 MVAr and Reactor-3
with a capacity of 42 MVAr, operate at a rated voltage of 420 V3 kV. Their design
incorporates advanced specifications to ensure optimal performance, including
rated currents and reactance values tailored for phase balancing and system
integrity. These reactors are integral for maintaining the reliability of the electrical
grid, especially in high- voltage applications.

7.4.9 Gas Insulated Substation(GIS)

A Gas-Insulated Substation is a high voltage substation where the major
structure are contained in a sealed environment with sulphur hexafluoride gas
(SF6) as the insulation medium. GIS technology is noted for its reliability
compact size and minimal maintenance requirements. The ratings for GIS are
 Fig 7.12 Gas Insulated Substation(GIS)

typically high, with voltages ranging from 72.5 kV up to 800 kV, making it well-
suited for urban areas where space is limited.
In terms of operation, GIS utiliz es breakers and disconnectors enclosed in a
metal-clad setup, ensuring protection against environmental conditions while
reducing the substation's footprint. It includes various components like circuit
breakers, disconnectors, earthing switches, current transformers, voltage
transformers, and gas density monitors.

7.5 TRANSFORMERS

7.5.1 Generator Transformer (GT)

The Generator Transformer (GT) in Phase III of the switchyard is a critical
component manufactured by Shandong Electrical Equipment's. With its robust
single-phase, double-coil, copper winding design, it facilitates efficient power
transformation. The GT's impressive 3 x 270 MVA capacity and high adaptability
to varying cooling needs (OFAF/ONAF/ONAN) make it suitable for high-load
conditions, operating reliably at a standard frequency of 50 Hz. Its voltage
regulation mechanism allows it to handle fluctuations seamlessly, ensuring a
stable power supply.
Technical specifications like a rated voltage of 420kV on the high-voltage side
and 22kV on the low-voltage side, along with corresponding current ratings,
demonstrate the GT's capacity to manage large-scale power flows. The mineral
oil insulation and YNd11 wiring group provide a reliable insulation system, while
the 16% impedance on the normal tap ensures proper voltage control.
Protection elements integrated within the GT, like differential protection,
impedance protection, over-excitation protection, and overload alarms, ensure its
operational safety and longevity. These protective measures are meticulously
designed to detect and respond to a wide range of abnormal operating conditions,
guarding the transformer and the system against potential damages.

7.5.2 Unit auxiliary Transformer (UAT)

The Unit Auxiliary Transformer (UAT), crafted by Shandong Electrical
Equipment's, is a three-phase, double-winding transformer essential for
delivering reliable power within the plant. With a robust 35 MVA capacity on
both primary and secondary sides and an innovative auto oil circulation air Fig
 cooling system, it operates effectively under the dual cooling methods of
ONAN/ONAF. The UAT is designed with a high-voltage side rated at 22 kV and
a low- voltage side at 6.9 kV, ensuring an efficient energy transfer at a rated
current of 918.5A HV and 2928.6A LV. Its 13% impedance voltage aligns with
the durability and stability needed for industrial power applications. Engineered
for outdoor use, it maintains a 50 Hz frequency and is connected in a Dyn1 wiring
group, offering reliability and adaptability under diverse working conditions.
7.5.3 STATION TRANSFORMER
The station transformer (ST) made by Shandong Power Equipment is
engineered for robust performance with a substantial rated output of 63 MVA,
addressing the needs of a modern switchyard. Designed with an Oil Natural Air
Natural (ONAN)/Oil Natural Air Forced (ONAF) cooling system, it is well-
equipped to manage thermal performance under varying load conditions. The
dual-rated power of 63000/35000-28000 kVA offers versatility in operation,
catering to both high and low demand scenarios.
Specification-wise, the ST operates at a high voltage (HV) level of 220kV, with
a permissible range of 8 X 1.25%, translating to efficient power transmission with
a current capacity of 165.3 A. The low voltage (LV) side offers two ratings,
6900V with a current of 2928.59 A and 11500V with 1405.72 A, suitable for
diverse operational demands. The YNyn0-yn0+d11 connection symbol denotes a
special winding connection that facilitates the transformer's adaptability across
different network configurations.
In terms of protection, the ST is likely to include a range of safety mechanisms
designed to safeguard against overloads, faults, and thermal risks. The technical
construction ensures reliable performance and longevity, with a three-phase
system that is the standard in high-capacity power application, ensuring balanced
distribution and consistent power quality.
 CHAPTER -8 TESTING INSTRUMENT

8.1 DIFFERENT TESTING KITS

8.1.1 Contact Resistance Meter

SCOPE introduces its next generation of hugely popular CRM series
contact resistance meters, CRM 100B+ and CRM200B+ in all new super light
avatars, based on cutting edge ultra
capacitor technology. CRM incorporates
some state-of-the-art hardware & smart
software features making it a must have tool
for testing & maintenance engineers.
Fig 8.1 Contact Resistance Meter

CRM directly measures micro-ohm values at 100/ 200 Amps DC under live EHV
switchyard conditions quickly & accurately.
CRM is specially designed to reliably measure micro-ohm contact resistances of
circuit breakers, isolators, busbar joints, earth switch joints, welded joints etc.,
under the hostile electrostatic noise found in live EHV switchyards up-to 765 kV.
Contact resistance measurement is very important for above mentioned
equipment's which are generally carrying large currents. Even small change in
contact resistance value can cause heavy power loss and overheating of contacts
or components which can lead to premature damage. Hence regular monitoring
of contact resistance of such equipment is essential for all companies in Power
Generation, Transmission & Distribution as part of their preventive maintenance.

8.1.2 Circuit Breaker Time Interval Meter

SCOT series of CB time Interval Meter from SCOP
are compact and reliable instrument to measure operating
time of all type of HV/EHV circuit breaker under charged
switchyard condition up to 400lv. SCOT M#K measure
and display CLOSE, OPEN time of main contacts of 3
pole connected end to end simultaneously.

Fig 8.2 Circuit Breaker Time Interval Meter

8.1.3 Secondary injection kit (Omicron)

The CMC 256plus is the first choice for applications requiring very high
accuracy. This unit is not only an excellent test set for protection devices of all
kinds but also a universal calibration tool. Its high precision allows the test and
calibration of a wide range of measuring devices, including: power quality (PQ)
measurement devices of class A and S, energy meters of class 0.2, measuring
transducers and phasor measurement units (PMU). The six current and four
voltage output channels of the CMC 256plus
are continuously and independently
adjustable in amplitude, phase, and
frequency.
Fig 8.3 Secondary injection kit
 CHAPTER-9 BALANCE OF PLANT

9.1 INTRODUCTION
The Balance of Plant (BOP) department in a thermal power plant is responsible
for the infrastructure and auxiliary systems required for the operation of the
power plant aside from the main power generation equipment. Here's some
basic information about the Balance of Plant department:
Definition: The Balance of Plant (BOP) encompasses all the systems and
components in a thermal power plant other than the main power generation
equipment like boilers, turbines, and generators. It includes various auxiliary
systems necessary for the efficient and safe operation of the plant.

9.1.1 Functions

The BOP department is responsible for the design, installation, operation, and
maintenance of the following systems and components:
• Water treatment and cooling systems: Water intake, treatment,
circulation, and cooling towers.
• Fuel handling systems: Coal handling, fuel storage, and preparation
systems.
• Ash handling systems: Collection, transportation, and disposal of ash
generated during combustion.
• Air quality control systems: Flue gas desulfurization (FGD),
electrostatic precipitators (ESP), and other emission control systems.
• Electrical systems: Transformers, switchgear, substations, and
electrical distribution networks.
• Instrumentation and control systems: Monitoring, control, and
automation systems for
• plant operation. Civil and structural works: Buildings, foundations,
roads, and drainage systems.
 • Fire protection and safety systems: Fire detection, suppression, and
emergency response systems.
• Coordination: The BOP department collaborates closely with other
departments within the power plant, including operations,
maintenance, engineering, and safety, to ensure seamless operation
and optimal performance of the entire plant

9.2 DM & RO PLANT

A DM/RO plant in a thermal power plant is an essential part of the water

Treatment system.
 SKID

Fig 9.1 SKID

9.1 COLLING TOWER

OVERVIEW
Cooling tower is used for the purpose of cooling the heated sea water. In
electricity generation process steam passes through the H.P, I.P, and L.P.
Turbines but there is some heat which is present reduces the efficiency for next
cycle. So this heat is transferred to the sea water via use of condenser.
Here the sea water is feed into the condenser which transfers the heat of steam
to the sea water. This sea water is transferred to the cooling tower through the
pipes. In cooling tower according to the design, it will flow to the upper head of
the cooling tower. At the top portion L.T motors are present which fetches the
cool air from the atmosphere. The flow of air is from top to ground which cools
the water.

Fig 9.2 Cooling tower

Here water free falls on the fins. There is some space for the circulation of natural
atmospheric air throughout the cooling tower. By this way water loses its heat and
water is now feed to the circulating water pump through underground water canal
system. This water is then feed to the condenser.
 CHAPTER-10 COAL HEANDLING PLANT

10.1 PROCESS OF COAL HANDLING PLANT

Here The Coal is feed into the coal bunker from Silo to the coal bunker.
The process of feeding from silo to the coal bunker is known as coal handling
plant. In this process the coal passes from many processes like crushing,
vibrating, screening, etc. First the coal is transferred to the stockpile from silo for
that process of transferring the coal from silo to the stockpile transferring
conveyor belt is used. To stock the coal here we use stacker-reclaimer mechanism
In this stacker-reclaimer mechanism we can put the coal from conveyor belt to
stockpile by stacking process and we can also get the coal from stockpile to the
conveyor belt by reclaiming process. The coal used in the plant is transported
from Mundra Port to the plant through a Conveyor belt which is 15Km long and
runs at a speed of 7 m/sec.
Now from the stockpile the coal is transferred to the crusher house by using flat
type conveyor belt. It feeds 2000 tons/hr. So, the capacity of the conveyor belt to
feed the coal in crusher house from stockpile is 2000 tons/hr. for the safety
purpose sprinkler is mounted throughout the conveyor belt. So, in case of fire on
the coal the sprinkler comes into action, and we can control the fire. It is an
automated system.
The sensor senses the situation, and the system takes the action. If the temperature
of atmosphere is increased above the critical limit so at that time possibility of
coal burning is increased so at that time the sensor senses the temperature of
atmosphere, and the sprinkler comes into action, and we can control the situation
and put it in a normal condition. And when the condition comes at a normal
condition sprinkler turns off.
Now at a crusher house the coal is crushed by the crusher. Crusher is one type of
machine which converts the lump type of coal into small particle by crushing
action. To run that crusher, we have to use high tension motor which is operated
by 6.6 KV and the motor we use H.T. induction type motor.
So now by crushing the lump type of
coal it now becomes small particle
and then We have to transfer that coal
to the vibrofeeder via conveyor belt.
We use flat type conveyor belt which
has capacity of 1200 tons/hr. In
vibrofeeder the coal passes through
vibrator for screening purpose.
At a screening process the coal passes
through the vibrator and if the big
particle presents in that it will be
separated. Small particle is feed into
the belt feeder and the big particle is
Fig 10.1 SILO

again crushed by secondary crusher and it is converted into small particle and
then it is feed directly into the belt feeder by conveyor belt.
 STACKER-RECLAIMER & STOCKPILE

Fig 10.2 Stacker

In Stacking process crushed coal are stored in a yard. this process is generally
used when boiler bunker level is full.

In reclaiming process, the stored coal is reclaimed for sending to boiler bunkers.
This process is used when boiler bunker level is low.
Both the process (stacking & reclaiming) is achieved by stacker reclaimer.

Stacker reclaimer has 3 types of movement.

• Luffing: which is up down in y plane +10 to-10
• Skewing: which is right left in X plan from its canter near about 105°
• Long travel: - which is travelling on its path up to approach and its speed
is 1 km/hr.
 REFERENCES
1. https://www.adanipower.com/operational-power-plants/mundra-gujrat
2. https://www.adanipower.com/newsroom/media-releases/adani-power-
mundra-plant-sets-a-record-in-power-generation
3. https://www.adanipower.com/operational-power-plant
4. https://nrec.com/en/#page1
5. https://nrec.com/en/#page2
6. https://nrec.com/en/#page3
7. https://scopetnm.com/index.php
8. https://www.omicronenergy.com/en/
9. Other technical details are taken from the technical diary of the Adani
Power Mundra