National Thermal Power Corporation: India's largest power producer

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CHAPTER-1
NATIONAL THERMAL POWER CORPORATION
1.1 INTRODUCTION
Fig1.1 Logo of the company
NTPC Ltd., formerly known as National thermal Power Cooperation Limited is an Indian public
Sector, undertaking, engaged in the business of generation of electricity and allied activity. It is
company incorporated under the Companies Act 1956 and a ‘Government Company’ within the
meaning of the act. The headquarters of the company is situated at New Delhi. NTPC’s main
business is generation and sale of electricity to state owned power distribution companies and
state electricity boards in India. The company also undertakes consultancy and turnkey project
contracts that involve engineering, project manager, construction management and operation and
management of power plants.
The company has also ventured into oil and gas exploration and coal mines activities. It is the
largest power company in India with an electric power generating capacity of 51,410MW.
Although the company has approx. 16% of the total national capacity, it contributes to over 25%
of total power generation due to its focus on operating its power plants at higher efficiency
levels. NTPC currently produces 25 billion units of electricity per month. It was founded by
Government of India in 1975, which now holds 69.74% of its equity shares on 30.06.2016.
1.2 HISTORY
The company was founded on 7th November ’75 as “National Thermal Power Cooperation
Private Limited”. It started work on its first thermal power project in 1976 at Shaktinagar in
Uttar Pradesh. In the same year its name changed to “NTPC Limited”. In 1983, NTPC began
commercial operations (of selling power) and earned profits of INR 4.5 Crores in FY 1982-83.
By the end of 1985, it had achieved power generation capacity of 2000MW. In 1986, it
completed synchronization of its first 500MW unit at Singrauli. In 1988, it commissioned two

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500MW units, one each in Rihand and Ramgundam. In 1989, it started a consultancy division. In
1992, it acquired Feroze Gandhi Unchachar Thermal Power Station of Uttar Pradesh. By the end
of 1994, its installed capacity crossed 15,000MW.
In 1995, it took over the Talchar Thermal Power Station from Orissa State Electricity Board. In
the year 1997, the Government of India conferred it with “Navratna” status. In the same year it
achieved milestone of generation of 100 billion units of electricity in one year. In 1998, it
commissioned its first naptha-based plant at Kayamkulam with a capacity of 350MW. In 1999,
its plant in Dadri, which had the highest plant load factor, was certified with ISO-14001. During
2000, it commenced construction of it’s first hydro-electric power plant, with 800MW capacity,
in Himachal Pradesh.
In 2002, it incorporated 3 subsidiary companies: “NTPC Electric Supply Company Limited” for
forwarding integration by entering into the business of distribution and trading of power; “NTPC
Vidyut Vyapar Nigam Limited” for meeting the expected rise in energy trading; “Hydro
Limited” to carry out the business of implementing and operating small and medium hydro-
power projects. In the same year its installed capacity crossed 20,000MW.
In October 2005, the company’s name was changed from “National Thermal Power
Corporation” to “NTPC Limited”. The primary reason for this was the company’s foray into
hydro and nuclear based power generation along with backward integration by coal mining. In
2006, it entered into an agreement with Government of Sri Lanka to set up two units of 250MW
each in Trincomalee in Sri Lanka. During 2008 and 2011 NTPC entered into joint ventures with
BHEL, Bharat Forge, NHPC, Coal India, SAIL, NMDC and NPCIL to expand its business of
power generation. By the end of 2010, its installed capacity crossed 31,000MW.
The company in 2009 joined forces with other state enterprise Rashtriya Ispat Nigam, Steel
Authority of India, Coal India, National Minerals Development Corporation and National
Thermal Power Corporation to invest in coal mining operations through a joint venture vehicle
named International Coal Ventures Private Limited. In July 2014, ICVL acquired a 65% stake in
the Bengal Coal Mine from Rio Tinto group.
Fig1.2 NTPC Thermal Power Plant

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1.3 OPERATIONS
NTPC operates from 55 locations in India, one location in Sri Lanka and two locations in
Bangladesh.
The scheduling and dispatch of all the generating stations owned by National Thermal Power
Corporation is done by respective Regional Load Dispatch Centre which are the apex body to
ensure integrated operation of the power system grid in the respective region. All these Load
Dispatch Centre come under Power System Operation Corporation Limited (POSOCO).
The total installed capacity of the company is 49943MW (including Joint Ventures) with own 18
coal-based and 7 gas-based stations and 6 coal-based and 1 gas-based in joint venture or
subsidiary company, located across the country.
NTPC has also stepped up its hydroelectric power (hydel) projects implementations.
NTPC has drafted its business plans of capacity addition of about 1000MW through renewable
resources by 2017. In this endeavor, NTPC has already commissioned 310MW solar PV
projects. 50 mw solar PV at Anantpur in Andhra Pradesh, 260MW solar PV at Bhadla in
Rajasthan and 250MW Solar PV at Mandsar in Madhya Pradesh are under implementation.
Fig1.3 NTPC Plants Across India
1.4 FUTURE GOALS
The company has developed a long term plan to become 128000MW Company by the year 2032.
NTPC limited is on an expansion spree to meet the power requirements of the country. It has
targeted to add 14,058MW in 12th plan (FY13 to FY17) of which it has already added 4,170MW
in the year 2012-13, 1835MW in the year 2013-14 , 1290MW in the year 2014-15 and 1150MW
form April 2015 to 30 November 2015.

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As on 30 November 2015, the company has 23004MW under construction. NTPC is diversifying
its capacity mix with lots of emphasis on renewable energy. As on 30.11.2015, NTPC has
110MW solar PV capacity under operation, 250MW under construction and 1260MW under
tendering. The company intends to add 10000MW of solar PV capacity in the next 5 years. On
18.07.2015, NTPC declared commercial its first hydro power plant at Koldam in the state of
Himachal Pradesh. By the year 2032, company has a long term plan to reduce its fossil fuel
capacity mix to 56% .
NTPC also plans to go global. The public sector company has signed a memorandum of
agreement with the Government of Sri Lanka and Ceylon Electricity Board for setting up a
500MW Coal Based Thermal Power Plant in the island nation. An MoU has also been signed
with Kyushu Electric Power Co. Inc., Japan, for establishing an alliance for exchange of
information and experts from different areas of the business. The company is also in the process
of finalizing an MoU with Nigeria for setting up power plant against allocation of LNG on long
term basis for NTPC plants in India. NTPC is also developing a joint-venture coal based power
plant 1,320MW (2x660) with Bangladesh Power development Board known as Bangladesh-India
friendship power company in Rampal, Bangladesh which is facing tremendous opposition from
the people of Bangladesh owing to the plant’s dangerously close proximity to the Sundarbans.
1.5 EMPLOYEES
As on 31st March 2015, the company had 24,067 employees. The attrition rate for the FY2014-
15, including the trainee employees and the employees working for the subsidiaries and JV, was
1.35%. Man MW ratio of the company has fallen from 0.77 in the FY11 to 0.61 in FY15. NTPC
has been awarded continuously as great places to work for in PSUs category.

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CHAPTER 2
BADARPUR THERMAL POWER STATION
2.1 INTRODUCTION
Badarpur thermal power station is located at Badarpur area in NCT Delhi. The power plant is
one of the coal based power plant of NTPC. The national power training institute (NPTI) for
North India region under the ministry of power, Government of India was established at
Badarpur in 1974 within the Badarpur thermal power plant (BTPS) complex.
The Badarpur thermal power station has installed capacity of 705MW. It is situated in North-
East corner of Delhi on Mathura road near Faridabad. It was the first central sector power plant
conceived in India, in 1965. It was originally conceived to provide power to neighboring states
of Haryana, Punjab, Jammu and Kashmir, U.P., Rajasthan and Delhi. But since year 1987 Delhi
has become its sole beneficiary. It was owned and conceived by Central Electric Authority. Its
construction was started in 1968 and the first unit was commissioned on 26th July 1973. The coal
for the plant is derived from Jharia coal fields. This was constructed under the ownership of
Central Electric Authority, later it was transferred to NTPC.
Fig2.1 Badarpur Thermal Power Station
It supplies power to Delhi city. It is one of the oldest plants in operation. It is currently in its 46th
year of operation. Its 100MW unit’s capacities have been reduced to 95MW. These units have
indirectly fired boiler, while 210MW have directly fired boiler. All the turbines are of Russian
design. Both turbines and boilers are supplied by BHEL. The boilers of stage 1 units are of
Czech design. The boilers of unit 4 and 5 are designed by combustion design engineering (USA).
The instrumentation of stage 1 units and unit 4 are of Russian design. Instrumentation of unit 5 is
provided by M/s Instrumentation Limited, Kota is of Kent design. The reasons for their long

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lasting working of machines are good manual maintenance, spare parts availability and good
number of expert technicians available. This plant has two machines of 210MW and three
machines of 95MW. In 1978 the management of the plant was transferred to NTPC, from CEA.
The performance of the plant increased significantly and steadily after takeover by NTPC till
2006, but now the plant is facing various issues. This company is capital intensive.
2.2 SET-BACKS
Being an old plant, Badarpur Thermal Power Station (BTPS) has little automation. Its
performance is deteriorating due to various reasons, like ageing, poor quantity and quality of
cooling water etc. it receives cooling water from Agra canal, which is an irrigational canal from
Yamuna River. Due to rising water pollution, the water of Yamuna is highly polluted. This
polluted water when goes into condenser, adversely affects the life of condenser tubes, resulting
in frequent tube leakages. This dirty water from tube leakage gets mixed into feed water cycle
causes numerous problems, like frequent boiler tube leakages and silica deposition on turbine
blades. Apart from poor quality, the quantity of water supply is also erratic due to lack of co-
ordination between NTPC and UP irrigation which manages Agra canal.
The quality of coal supplied has degraded considerably. At worst times there were many units
tripping owing to poor quality. The poor coal quality also puts burdens on equipment like mills
and their performance also goes down. The coal for the plant is also fetched from far away, that
makes the total fuel cost double of coal cost at coal mine. This factor coupled with ageing and
old design makes the electricity of plant costlier.
Presently the management is headed by Mr. N.K. Sinha, general manager.
The cost of power from Badarpur is Rs. 4.62per KWH making it one of the most costly in India.
According to 2015 study, the Badarpur power plant is the most polluting power plant in India.
The plant contributed only 8% of the Delhi’s electric power but produced 80-90% of city’s
particulate matter pollution from energy sector.During great smog of Delhi, the power plant was
shut down to alleviate acute air pollution but was restarted on March 16, 2017.
Fig2.2 Emissions from the plant

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CHAPTER-3
OBJECTIVE OF TRAINING
Power industry is a multi- disciplinary, highly capital intensive industry. Human element is the
most vital input of the Power Sector. Power generating stations require technically trained
manpower for project planning, implementation, erection, commissioning, testing, O&M
including transmission and distribution of power. No formal studies available in educational
institutions can equip a person with knowledge of different inputs required for the job
performance in Power Sector. Special training becomes necessary for the personnel at every
level in the industry to keep abreast with rapidly advancing state of the-art in the Power Industry.
Power is basic to national development and industrialization, and thus making it imperative to
have optimum efficiency. It provides exposure to turn us into industry experts and get proper
guidance about the industrial culture. The objective of industrial trainings are:
To expose students to the ‘real’ working environment and get acquainted with the organization
structure, business operation and administrative functions.
To have hand on experience in the student’s related field so that they can relate and reinforce
what has been taught at the university.
To set the stage for future recruitment by potential employers.

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CHAPTER-4
THERMAL POWER PLANT
4.1 INTRODUCTION
A thermal power plant is a power plant in which heat energy is converted to electric power. In
most of the cases in the world the turbine is steam-driven. Water is heated, turns into steam and
spins a steam turbine which drives an electrical generator. After it passes through the turbine, the
steam is condensed in a condenser and recycled to where it was heated, this is known as Rankine
cycle. The greatest variation in the design of thermal power station is due to the different heat
sources; fossil fuel dominates here, although nuclear heat energy and solar heat energy are also
used. Some prefer to use the term Energy Centre because such facilities converts forms of heat
energy to electrical energy. Certain thermal power plants also are designed to produce heat
energy for industrial purposes, or district heating or desalination of water, in addition to
generating electrical power.
Energy efficiency of a conventional thermal power plant, considered stable energy produced as a
percent of heating value of the fuel consumed is typically 33% to 48%.
The efficiency is limited and governed by Laws of Thermodynamics. The energy of a thermal
power plant not utilized in power production must leave the plant in the form of heat o
environment. This waste heat can go through a condenser and be disposed off with cooling water
or in cooling towers. If the waste heat is instead utilized for district heating, it is called
cogeneration. The Carnot efficiency dictates that higher efficiencies can be attained by
increasing the temperature of steam.
Fig 4.1 Diagram of a Thermal Power Plant

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4.2 PARTS OF THERMAL POWER PLANT
Fig4.2 Flow Diagram of Thermal Power Plant
4.2.1 BOILER AND STEAM CYCLE
In the Nuclear plant field, steam generators refers to a specific type of a large heat exchanger
used in a pressurized water reactor (PWR) to thermally connect the primary and secondary
systems, which generates steam. Fossil fuel steam generator includes an economizer, a steam
drum and furnace with its steam generating tubes and super heater coils. Necessary safety walls
are located at suitable points to leave excessive boiler pressure. The air and flue gas path
equipment; Forced Draft Fan (FD), Air Preheater, Boiler, Furnace, Induced Draft Fan, Fly Ash
Collectors and the Flue Gas stack.
4.2.1.1 Feed Water Heating and Deaeration
The boiler feed water used in steam boiler is a means of transferring heat energy from the
burning fuel to the mechanical energy of the spinning steam turbine. The total feed water
consists of recirculate condensate water and purified make-up water. The make-up water is
highly purified before used to minimize corrosion at high temperature and pressure, such that the
demineralizers produces water so pure that it becomes electrical insulators, with conductivity in
the range of 0.3 to 1.0 µ-sec per centi-meter.
4.2.1.2 Boiler Operations
The boiler is a rectangular furnace of about 50 feet on a side and about 130 feet tall. It’s walls are
made of a web of high pressure steel tubes about 2.3 inches in dia. Pulverized coal is air blown
into the furnace through burners and is ignited to rapidly burn. The thermal radiation heats the
water that circulates through boiler tubes. The water absorbs heat and changes to steam. The

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saturated steam is converted to superheated steam (540⁰C) to prepare it for turbine. Plants that
use gas turbines to heat use boilers known as Heat Recovery Steam Generators (HRSG)
4.2.1.3 Boiler Furnace and Steam Drum
The water enters the boiler through a section in the convection pass called the Economizer. From
the economizer it passes to the steam drum and from there it goes to inlet headers at the bottom
of the water walls. From these headers the water rises through the water walls of the furnace
where some of it is turned into steam and the mixture of water and steam then reenters the steel
drum. This process may be driven by natural circulation or assisted by pumps. In the steam
drum, the steam is passed through a series of steam separators and dryers that remove water
droplets from steam. The dry steam then flows into the super heater coils.
4.2.1.4 Super Heater
Fossil fuel power plants often have a super heater in the steam generating furnace. The steam
passes through drying equipment inside the steam drum, onto the super heater, a set of tubes in
the furnace. The superheated steam is then piped through the main steam lines to the halves
before the high pressure turbines.
4.2.1.5 Steam Condensing
The condenser condenses the steam from exhaust of turbine into liquid to allow it to be pumped.
The condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of
the cycle increases. The surface condenser is a shell and tube heat exchanger in which cooling
water is circulated through tubes.
4.2.1.6 Reheater
Power plant may have a reheater section containing tubes heated by hot flue gasses outside the
tube. Exhaust steam from high pressure turbines is passed through these heated tubes to collect
more energy before driving the intermediate and then the low pressure turbines.
4.2.1.7 Air Path
External fans are provided to give sufficient air for combustion. A primary fan pass through
pulverized coal dust and carries it to burners for injection into furnace. The secondary fan takes
air form atmosphere and first warms the air in air preheater for better economy and is mixed with
coal/ primary air flow in burners.
4.2.1.8 COOLING TOWERS
Cooling Towers are evaporative coolers used for cooling water or other working medium to near
the ambivalent web-bulb air temperature. Cooling tower use evaporation of water to reject heat
from processes such as cooling the circulating water used in oil refineries, Chemical plants,

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power plants and building cooling, for example. The tower vary in size from small roof-top units
to very large hyperboloid structures that can be up to 200 meters tall and 100 meters in diameter,
or rectangular structure that can be over 40 meters tall and 80 meters long. Smaller towers are
normally factory built, while larger ones are constructed on site.
The primary use of large , industrial cooling tower system is to remove the heat absorbed in the
circulating cooling water systems used in power plants , petroleum refineries, petrochemical and
chemical plants, natural gas processing plants and other industrial facilities . The absorbed heat is
rejected to the atmosphere by the evaporation of some of the cooling water in mechanical forced-
draft or induced draft towers or in natural draft hyperbolic shaped cooling towers as seen at most
nuclear power plants.
4.2.1.9 THREE PHASE TRANSMISSION LINE
Three phase electric power is a common method of electric power transmission. It is a type of
polyphase system mainly used to power motors and many other devices. A Three phase system
uses less conductor material to transmit electric power than equivalent single phase, two phase,
or direct current system at the same voltage. In a three phase system, three circuits reach their
instantaneous peak values at different times. Taking one conductor as the reference, the other
two current are delayed in time by one-third and two-third of one cycle of the electrical current.
This delay between “phases” has the effect of giving constant power transfer over each cycle of
the current and also makes it possible to produce a rotating magnetic field in an electric motor.
At the power station, an electric generator converts mechanical power into a set of electric
currents, one from each electromagnetic coil or winding of the generator. The current are
sinusoidal functions of time, all at the same frequency but offset in time to give different phases.
In a three phase system the phases are spaced equally, giving a phase separation of one-third one
cycle. Generators output at a voltage that ranges from hundreds of volts to 30,000 volts. At the
power station, transformers: step-up” this voltage to one more suitable for transmission.
After numerous further conversions in the transmission and distribution network the power is
finally transformed to the standard mains voltage (i.e. the “household” voltage).
The power may already have been split into single phase at this point or it may still be three
phase. Where the step-down is 3 phase, the output of this transformer is usually star connected
with the standard mains voltage being the phase-neutral voltage. Another system commonly seen
in North America is to have a delta connected secondary with a center tap on one of the windings
supplying the ground and neutral. This allows for 240 V three phase as well as three different
single phase voltages( 120 V between two of the phases and neutral , 208 V between the third
phase ( known as a wild leg) and neutral and 240 V between any two phase) to be available from
the same supply.
4.2.1.10 ELECTRICAL GENERATORS

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An Electrical generator is a device that converts kinetic energy to electrical energy, generally
using electromagnetic induction. The task of converting the electrical energy into mechanical
energy is accomplished by using a motor. The source of mechanical energy may be a
reciprocating or turbine steam engine, , water falling through the turbine are made in a variety of
sizes ranging from small 1 hp (0.75 kW) units (rare) used as mechanical drives for pumps,
compressors and other shaft driven equipment , to 2,000,000 hp(1,500,000 kW) turbines used to
generate electricity. There are several classifications for modern steam turbines.
Steam turbines are used in all of our major coal fired power stations to drive the generators or
alternators, which produce electricity. The turbines themselves are driven by steam generated in
‘Boilers’ or ‘steam generators’ as they are sometimes called.
Electrical power station use large stem turbines driving electric generators to produce most
(about 86%) of the world’s electricity. These centralized stations are of two types: fossil fuel
power plants and nuclear power plants. The turbines used for electric power generation are most
often directly coupled to their-generators .As the generators must rotate at constant synchronous
speeds according to the frequency of the electric power system, the most common speeds are
3000 r/min for 50 Hz systems, and 3600 r/min for 60 Hz systems. Most large nuclear sets rotate
at half those speeds, and have a 4-pole generator rather than the more common 2-pole one.
Energy in the steam after it leaves the boiler is converted into rotational energy as it passes
through the turbine. The turbine normally consists of several stage with each stages consisting of
a stationary blade (or nozzle) and a rotating blade. Stationary blades convert the potential energy
of the steam into kinetic energy into forces, caused by pressure drop, which results in the rotation
of the turbine shaft. The turbine shaft is connected to a generator, which produces the electrical
energy.
4.2.2 STEAM TURBINE GENERATORS
The turbine generator consists of a series of steam turbines interconnected to each other and the
generator to a common shaft. As steam moves through the system and losses pressure and
thermal energy, it expands in volume, requiring increasing diameter and longer blades at each
succeeding stage to extract the remaining energy. It is so heavy that it must be kept turning
slowly even when shut down (at 3 rpm) so that the shaft will not bow and become unbalanced.
Super-heated steam is derived through 14-16 inch diameters piping at 160 atm and 540⁰C to the
high pressure turbine, where it falls to 41 atm and 320⁰C. Oil lubrication is provided to further
reduce the friction between shaft and bearing surface and to limit the heat generated.
4.2.3 STACK GAS PATH AND CLEANUP
As the combustion flue gasses exit the boiler it is routed through a rotating flat basket of metal
mesh which picks up heat and returns it to incoming air as the basket rotates. This is called the
air preheater. The flue gas contains nitrogen along with combustion products carbon dioxide,
sulfur dioxide and nitrogen oxides. The sulfur and nitrogen oxide pollutants are removed by

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stack gas scrubbers which use a pulverized limestone or other wet slurry to remove those
pollutants from exit stack gas. Other devices use catalysts to remove Nitrous Oxide compounds
from the flue gas stream. A typical flue gas maybe 150-180m tall to disperse the remaining flue
gas components in atmosphere.
4.2.3.1 Fly Ash Collections
Fly Ash is removed by fabric bag filters or electrostatic precipitators. Once removed, the fly ash
byproduct can be used in manufacturing of concrete. It is located at the outlet of the furnace,
before the induced draft fan. The fly ash is periodically removed from collection hoppers.
4.2.3.2 Bottom Ash Collection and Disposal
At the bottom of the furnace, there is a hopper for collection of bottom ash.
4.2.4 AUXILIARY SYSTEMS
These include:
1. Boiler make-up water treatment plant and storage
2. Fuel preparation system
3. Barring gear
4. Oil system
5. Generator cooling
6. Generator high-voltage system
7. Monitoring and alarm system
8. Battery supplied emergency lighting and communication
9. Circulating water system
4.2.5 TRANSPORT OF COAL
Raw coal is transported from coal mines to power station sites by trucks or railways. The coals
received at sites are of different sizes and are unloaded at site by rotary dumpers or side-tilt
dumpers onto conveyor belts. The coal is conveyed to crushers and then the crushed/pulverized
coal is sent by belt conveyors to storage.

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CHAPTER-5
LIGHTING
5.1 LIGHTING TERMINOLOGIES
5.1.1 WATT (W)
It is the unit corresponding to the rate of energy consumption in an electrical circuit.
5.1.2 LUMENS
It is the unit describing the amount of light as seen by the human eye that is given off by the light
bulbs.
5.1.3 EFFICIENCY
It is the amount of light that comes out of a light bulb compared to the electrical energy that goes
into it. Efficiency is an output over an input.
5.1.4 COLOUR RENDITION
Some bulbs make things they are illuminating look a bit different than they really are. This
property is caller Colour Rendition.
5.1.5 COLOUR TEMPERATURE
It tells us what the light from the lamp looks like:
A low colour temperature – (~2600K) the light from lamp appears warm, mostly red, yellow or
orange tint. A 4100K lamp is a cool white lamp, meaning it produces stronger green, blue or
violet colors.
Fig5.1 Temperature-Color Scale

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5.1.6 EFFICACY
The performance measure for electric lamps –Efficacy is measured in units of lumens per watt
(Lu/W). –This is not a measure of efficiency since it has units.
Efficacies vary with type and size of lamps.
A 100 watt incandescent lamp has about 17 lumens per watt
A modern T8 lamp with electronic ballast has about 100 lumens per watt. –To calculate the
efficacy for a lamp that requires ballast, you must add the ballast power to the lamp power to get
the correct total wattage input. The higher the lumen per watt rating of a lamp the better meaning
greater light output for a fixed wattage input.
5.1.7 LUX
Lighting levels or illuminances are measured in Luxwith a light meter. One Luxis one lumen per
square metre. Lighting level standards are set by the Illuminating Engineering Society (IES), and
are listed in detail in the IES Lighting Handbook. –Lighting standards for watts/square metre for
common buildings are listed in the ASHRAE 90.1 commercial building code, and the IES
requirements are referenced. ASHRAE 90.1 is an IEC standard.
5.2 TYPES OF LIGHTS
1. Incandescent
2. Tungsten Halogen
3. Compact Fluorescent
4. Full-Size Fluorescent
5. Mercury Vapor
6. Metal Halide
7. High Pressure sodium
8. Low Pressure Sodium
9. LED
5.3 INDOOR LIGHTING
Common indoor bulbs are incandescent with 40W or 60W but there are other kind of light bulbs
like CFLs and LEDs.
5.3.1 Incandescent bulbs
It produces light with a thin wire called tungsten filament is heated by electricity running
through it making it so hot that it starts to glow brightly. (40W, 60W)

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Fig5.2 Incandescent Lamp
5.3.2 Compact florescent lamps (CFLs)
They work by running electricity through gas inside the coils, exciting the gas and producing
light. There’s a coating on the spirals which make the light white. (9W, 13W)
Fig5.3 CFLs
5.3.3 Light emitting diode (LEDs)
While these are most efficient bulbs to date, they are not without problems. The light they
produce looks white. LEDs contain a lot of blue light, too much of which can have negative
effects on human health & wildlife. (6W, 9.5W)

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Fig5.4 LED Light
5.4 OUTDOOR LIGHTING
These are usually different from those bulbs used indoors because they need to be much brighter
and last longer.
5.4.1 Halogen bulbs
Often found as spotlight, floodlights, in car’s headlights or at stadium. They work by running
electricity through tungsten filament but there’s halogen gas inside the bulb. They last longer
than incandescent, but are much brighter and burn much hotter (53W, 72W, 75W...)
Fig5.5 Halogen Light
5.4.2 Metal Halide
Commonly used as streetlights, parking lot lights & stadium lights. They are very bright and
contribute to a lot of light pollution. They produce white light and have good colour rendition
and is also fairly efficient (250W, 400W, 1000W,..)

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Fig5.6 Metal Halide
5.4.3 High Pressure Sodium (HPS)
Most commonly used street light. Produces light by running electricity through a mixture of
gases, which produces a yellow-orange light. It requires less maintenance. (159W, 250W,..)
Fig5.7 HPS Lamps
5.5 BALLASTS
Except for incandescent lamps, all other lamps are discharge lamps that require ballast to
start and run the lamps.
The phenomenon of ionization of gas in the tube takes place at a relatively high potential
difference & temperature. After the arc is set up, the temp can be brought down to normal. For
this three methods are employed: pre-heat, instant start and rapid start.
There are mainly 3 types of ballasts: Electronic, magnetic and hybrid. Ballasts are classified as:
1. Resistors: fixed resistor and self-variable resistor
2. Reactive ballasts
3. Electronic and magnetic ballasts

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Fig5.8 Ballasts
5.6 ELECTRIC HOLDER
These are used in various devices to fix batteries, bulbs, lamps, fuse etc. Types of holders:
1. Bayonet cap
2. Edison screw cap
3. Linear halogen capsules
4. Halogen capsules
5. Push fit light bulbs
6. Architectural strip lights
Fig5.9 Electric Holder
5.7 CHOKE
Normal operating voltage of tube light is about 110 but naturally available voltage is 240V hence
choke comes into picture which gives 110V output. Electronic chokes are thus now most widely
used as PF is very high so current drawn will be low. Also losses in copper are high the
electronic choke and also, there’s no light flickering while starting electronic choke tube in
comparison to copper choke.

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Fig5.10 Choke
5.8 STARTER
For initiating the light (to ionize the gas in the tube), the system requires 800-1000V to provide
this starter has been used, which block the current flowing from the choke to light hence the
voltage will build up across the load. Once the maximum voltage is reached which starter can
withstand the starter closes the circuit & the buildup voltage is applied across the tube light.
Fig5.11 Circuit Diagram of a Starter

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Fig5.12 Starter
5.9 WORKING OF A TUBE
Fig5.13 Working of a Tube
Fig5.14 Circuit diagram of a Tube

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CHAPTER-6
HIGH TENSION MOTORS
6.1 INDUCTION MOTOR
An electrical motor is such an electromechanical device which converts electrical energy to
mechanical energy. In case of 3 phase AC operation, the most widely used motor is three phase
induction motor as this type of motor doesn’t require any starting device or we can say they are
self-starting. The motor consists of two major parts:
6.1.1 STATOR
It is made up of number of slots to construct a 3-Ø winding circuit which is connected to 3-Ø AC
source. The windings are arranged in such a manner that they produce a rotating magnetic field
after 3-Ø AC supply is given to them.
6.1.2 ROTOR
It consists of cylindrical laminated core with parallel slots that can carry conductors. Conductors
are heavy copper or aluminum bars which fits in each slots and they are short circuited by the
end rings. The slots are not exactly parallel to the axis of shaft but are slotted a little skewed as
this arrangement reduces magnetic humming noise and can avoid stalling of motor (cogging).
Three phase induction motors are:
1 Self-starting
2 Robust in construction
3 Economical
4 Easier to maintain
5 Less armature reaction and brush sparking because of absence of commutators and brushes

23
Fig6.1 Windings of Induction Motor
6.2 SQUIRREL CAGE INDUCTION MOTORS
The name for the motor is squirrel cage because of the type of rotor used. Almost 95% of the
induction motors used is of this type. This type of rotor consists of a cylindrical laminated core
with parallel slots for carrying the rotor conductors, which are thick heavy bars of copper or
aluminum or its alloy. The bars are inserted from one end of rotor and as one bar in each slot.
There are end rings which are welded or electrically braced or bolted at both ends of rotor, thus
maintaining electrical continuity. These end rings are short circuited, after which they give a look
similar to squirrel thus the name.
Fig6.2 Squirrel Cage Induction Motor

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Fig6.3
6.3 HIGH TENSION MOTORS
Motors operating at 6.6kV or greater voltages are referred to as H.T. Motors. H.T. Motors are
typically star connected. Such a configuration is chosen to reduce the insulation required to cover
the stator winding (armature) which directly affects the size and cost of motor as phase voltage is
lower in case of star connected motor. The 6.6kV or 11kV is the line voltage . the neutral of the
motor is not grounded. Grounding is done at the feeder end; this ensures that only one neutral is
grounded for reference. If motor neutral is grounded, in case of short circuit fault, heavy current
will flow through motor winding and can easily damage the motor. These motors have double
layer winding. Typical rating of H.T. Motors is 6.6kV, 21A, 1485 rpm and 187kW. Its winding
is based on the pitch.
Fig6.4 Stator winding of Induction Motor
6.4 INSULATION

25
For insulation on stator six layer winding of double layer winding of mica seals are used. It’s one
layer provides insulation up to 1.25kV.
Another component known as Ecoflex is also used for insulation. It seals the air gap and its one
layer provides 0.85kV protection and it is red in colour.
In H.T. Motors, to attach wires we don’t use the process of soldering. Rather gas bridging is
done by metal composed of tin, iron etc. as soldering will melt on such high temperature.
Fig6.5 Insulation of Wires
6.5 POLARIZATION INDEX TEST
PI testing is designed to check specific issues in a motor including moisture, suitability of the
operation and the gradual insulation deterioration of the machinery. It is an effective and
efficient way to evaluate performance of the motor. A minimum PI value of 2.0 is necessary for
induction motors. By doing PI test, one can prolong the life span and durability of motor by
preventing unnecessary downtime, loss of profits and expensive repairs. PI machine is connected
at the supply to stator (as load). Three reading are taken at 15s, 60s and 15 min. the readings are
observed and if they are not in ideal range, then the machine is heated to remove moisture at
about 120⁰C for 1-2 hours depending upon moisture content present and size.

27
CHAPTER-7
LOW TENSION MOTORS
7.1 INTRODUCTION
These motors work under 1kV and LT Motor require more current than H.T. Motors. They are
mostly delta connected. Following are the main reasons due to which low voltage motor’s stators
are delta connected:
1. The insulation requirement will not be a problem as voltage level is less.
2. Starting current won’t be a problem as starting power in all will be less.
3. No problem of voltage dips
4. Starting torques will be large as motors are of small capacity and hence stator should be
connected in delta to have more current and hence more starting torque.
L.T. Motors have normal air gap. In these motors, insulation is provided by a fiber glass sleeving
in the connections and paper insulation is provided to the windings. These insulations can protect
till 50⁰C.
Fig7.1 L.T. Induction Motor
7.2 STARTING OF MOTOR
L.T. Motors can be started in the following ways:
1. Direct online starter
2. Star- Delta starter
3. Auto transformer starter
4. Semi-Automatic star delta starter
5. Automatic Star-Delta starter

28
In the present condition, direct online starter was used. The motor was supplied voltage slowly.
Direct online starting has high starting current hence the supply is increased slowly so that the
speed doesn’t shoot up instantly. Once the speed is reached, the current decreases.
The conductors used in the rotor were about 6mm in diameter. The core material is made of
CRGO. A typical L.T. machine is of rating 7.5HP, 55kW, 415V/450V and 1475 rpm.
7.3 BEARINGS
A bearing is a machine element that constraints relative motion to only the desired motion, and
reduces friction between the moving paths. Most bearings facilitate the desired motion by
minimizing friction. They are classified broadly according to the types of operation, the motions
allowed or to the directions of the load applied to the parts. There are six common:
1. Plain bearing
2. Rolling element bearing
2.1 Ball bearing
Fig7.2 Ball Bearing
2.2 Roller bearing
Fig7.3 Roller Bearing
3. Jewel bearing
4. Fluid bearing
5. Magnetic bearing
6. Flexure bearing
(Clearance is the gap between ball and outer ring in ball bearing.)

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7.4 LT Switchgear
It is classified in following ways:-
7.4.1 MAIN SWITCH
Main switch is control equipment which controls or disconnects the main supply. The main
switch for 3 phase supply is available for tha range 32A, 63A, 100A, 200Q, 300A at 500V
grade.
7.4.2 FUSES
With Avery high generating capacity of the modern power stations extremely heavy carnets
would flow in the fault and the fuse clearing the fault would be required to withstand
extremely heavy stress in process.
It is used for supplying power to auxiliaries with backup fuse protection. Rotary switch up to
25A. With fuses, quick break, quick make and double break switch fuses for 63A and 100A,
switch fuses for 200A, 400A, 600A, 800A and 1000A are used.
7.4.3 CONTRACTORS
AC Contractors are 3 poles suitable for D.O.L Starting of motors and protecting the
connected motors.
7.4.4 OVERLOAD RELAY
For overload protection, thermal over relay are best suited for this purpose. They operate
due to the action of heat generated by passage of current through relay element.
7.4.5 AIR CIRCUIT BREAKERS
It is seen that use of oil in circuit breaker may cause a fire. So in all circuits breakers at large
capacity air at high pressure is used which is maximum at the time of quick tripping of
contacts. This reduces the possibility of sparking. The pressure may vary from 50-60
kg/cm^2 for high and medium capacity circuit breakers.

30
CHAPTER-8
SWITCHYARD
8.1 INTRODUCTION
A switching station is a sub-station without transformers and operating only at single voltage
level. Switching stations are sometimes used as collector and distribution stations. Sometimes
they are used for switching the current to back-up lines or for parallelizing circuits in case of
failure. The generators from the power station supply their power into the yard onto the generator
bus on one side of the yard, and the transmission lines take their power from a feeder bus on the
other side of the yard.
An important function performed by a sub-station is switching, which is connecting and
disconnecting of transmission lines or other components to and from the system. Switching
systems may be planned or unplanned. A transmission line or other component may be de-
energized for maintenance or for new construction. To maintain reliability of supply, companies
aim at keeping the system up and running while performing maintenance. Unplanned events are
caused by a fault in a transmission or other events for example:
1. A line is hit by lightning and develops an arc
2. A tower is blown down by high wind
The function of switching station is to isolate the faulty portion of the system in the shortest
possible time, de-energize faulty equipment protects it from further damage and isolating the
fault helps keep the rest of the electrical grid operating with stability.
Fig8.1 Symbols Used

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Fig8.2 SLD of Switchyard
8.2 ISOLATOR
A disconnector, disconnect switch or isolator is used to ensure that an electrical switch is
completely de-energized for service or maintenance. Such switches are often found in electrical
distribution and industrial applications, where machinery must have it’s source of driving power
removed for adjustment or repair. Unlike load switches and circuit breakers, isolators lack a
mechanism for supervision of electric arcs, which occurs when conductors carrying high currents
are electrically interrupted. Thus, they are off-load devices, intended to be opened only after
circuit has been interrupted by some other controlled device. An isolator combines properties of
a disconnector and a load switch so as to provide safety isolation function while being able to
make and break nominal currents. Hence, the circuit breakers operate before the isolator. The
isolators have male and female contacts.
Fig8.3 Isolator
8.3 CIRCUIT BREAKERS

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A circuit breaker is an automatically operated electrical switch designed to protect an electrical
circuit from damage caused by excess current, typically resulting from an overload or short-
circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which
operates once and then must be replaced, a circuit breaker can be reset to resume normal
operation. Circuit breakers are made in varying sizes. Types of circuit breakers are:
1. Low voltage circuit breakers (<1000Vac)
1.1 Miniature circuit breaker (MCB) : (<100Amp)
1.2 Molded case circuit breaker (MCCB): up to 2500 Amp
1.3 Low voltage power circuit breakers can be molded in multi tiers in switch boards or
switch gears
2. Magnetic circuit breakers
3. Thermal Magnetic circuit breakers
4. Magnetic hydraulic circuit breakers
5. Common trip breakers
6. Medium voltage circuit breakers: (1kV to 72kV)
6.1 Vacuum circuit breakers
It works on the principle that vacuum is used to save the purpose of insulation and it
implies that pr. Of gas at which breakdown voltage independent of pressure. It regards of
insulation and strength, vacuum is superior dielectric medium and is better that all other
medium except air and sulphur which are generally used at high pressure.
6.2 Air circuit breakers
In this the compressed air pressure around 15 kg per cm^2 is used for extinction of arc
caused by flow of air around the moving circuit . The breaker is closed by applying
pressure at lower opening and opened by applying pressure at upper opening. When
contacts operate, the cold air rushes around the movable contacts and blown the arc. It
has the following advantages over OCB:-
i. Fire hazard due to oil are eliminated.
ii. Operation takes place quickly.
iii. There is less burning of contacts since the duration is short and consistent.
iv. Facility for frequent operation since the cooling medium is replaced constantly.
6.3 SF6 circuit breakers
This type of circuit breaker is of construction to dead tank bulk oil to circuit breaker but
the principle of current interruption is similar to that of air blast circuit breaker. It simply
employs the arc extinguishing medium namely SF6. the performance of gas . When it is
broken down under an electrical stress. It will quickly reconstitute itself.

33
6.4 Minimum Oil circuit breakers
These use oil as quenching medium. It comprises of simple dead tank row pursuing
projection from it. The moving contracts are carried on an iron arm lifted by a long
insulating tension rod and are closed simultaneously pneumatic operating mechanism by
means of tensions but throw off spring to be provided at mouth of the control the main
current within the controlled device.
Fig8.4 Circuit Breaker
8.4 WAVE TRAP
A line trap (high frequency stopper) is a maintenance-free parallel resonant circuit, mounted in
line on high voltage AC transmission power lines to prevent the transmission of high frequency
(40kHz -1000kHz) carrier signals of poor line communication to unwanted destinations. Line
traps are cylinder like structures and are also known as wave trap. It acts as barrier to prevent
signal losses. The inductive reactance of the line trap presents a high reactance to high frequency
signals but a low reactance to mains frequency. It is also used to attenuate the shunting effect of
HV lines.
Fig8.5 Wave Trap
8.5 TRANSFORMER

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A transformer is a device that transfers electrical energy from one circuit to another by magnetic
coupling with out requiring relative motion between its parts. It usually comprises two or more
coupled windings, and in most cases, a core to concentrate magnetic flux. An alternating voltage
applied to one winding creates a time-varying magnetic flux in the core, which includes a voltage
in the other windings. Varying the relative number of turns between primary and secondary
windings determines the ratio of the input and output voltages, thus transforming the voltage by
stepping it up or down between circuits. By transforming electrical power to a high-
voltage,_low-current form and back again, the transformer greatly reduces energy losses and so
enables the economic transmission of power over long distances. It has thus shape the electricity
supply industry, permitting generation to be located remotely from point of demand. All but a
fraction of the world’s electrical power has passed trough a series of transformer by the time it
reaches the consumer.
Fig8.6 Transformer
8.5.1 BASIC PRINCIPLES
The principles of the transformer are illustrated by consideration of a hypothetical ideal
transformer consisting of two windings of zero resistance around a core of negligible
reluctance. A voltage applied to the primary winding causes a current, which develops a
magneto motive force (MMF) in the core. The current required to create the MMF is termed the
magnetizing current; in the ideal transformer it is considered to be negligible, although its
presence is still required to drive flux around the magnetic circuit of the core. An electromotive
force (MMF) is induced across each winding, an effect known as mutual inductance. In
accordance with faraday’s law of induction, the EMFs are proportional to the rate of change of
flux. The primary EMF, acting as it does in opposition to the primary voltage, is sometimes
termed the back EMF”. Energy losses An ideal transformer would have no energy losses and
would have no energy losses, and would therefore be 100% efficient. Despite the transformer
being amongst the most efficient of electrical machines with ex the most efficient of electrical
machines with experimental models using superconducting windings achieving efficiency of
99.85%, energy is dissipated in the windings, core, and surrounding structures. Larger
transformers are generally more efficient, and those rated for electricity distribution usually

35
perform better than 95%. A small transformer such as plug-in “power brick” used for low-power
consumer electronics may be less than 85% efficient. Transformer losses are attributable to
several causes and may be differentiated between those originated in the windings, some times
termed copper loss, and those arising from the magnetic circuit, sometimes termed iron loss. The
losses vary with load current, and may furthermore be expressed as “no load” or “full load” loss,
or at an intermediate loading. Winding resistance dominates load losses contribute to over 99%
of the no-load loss can be significant, meaning that even an idle transformer constitutes a drain
on an electrical supply, and lending impetus to development of low-loss transformers. Losses in
the transformer arise from: Winding resistance Current flowing trough the windings causes
resistive heating of the conductors. At higher frequencies, skin effect and proximity effect create
additional winding resistance and losses. Hysteresis losses Each time the magnetic field is
reversed, a small amount of energy is lost due to hysteresis within the core. For a given core
material, the loss is proportional to the frequency, and is a function of the peak flux density to
which it is subjected. Eddy current Ferromagnetic materials are also good conductors, and a solid
core made from such a material also constitutes a single short-circuited turn trough out its entire
length. Eddy currents therefore circulate with in a core in a plane normal to the flux, and are
responsible for resistive heating of the core material. The eddy current loss is a complex function
of the square of supply frequency and inverse square of the material thickness. Magnetostriction
Magnetic flux in a ferromagnetic material, such as the core, causes it to physically expand and
contract slightly with each cycle of the magnetic field, an effect known as magnetostriction. This
produces the buzzing sound commonly associated with transformers, and in turn causes losses
due to frictional heating in susceptible cores. Mechanical losses In addition to magnetostriction,
the alternating magnetic field causes fluctuating electromagnetic field between primary and
secondary windings. These incite vibration with in near by metal work, adding to the buzzing
noise, and consuming a small amount of power. Stray losses Leakage inductance is by itself loss
less, since energy supplied to its magnetic fields is returned to the supply with the next half-
cycle. However, any leakage flux that intercepts nearby conductive material such as the
transformers support structure will give rise to eddy currents and be converted to heat. Cooling
system Large power transformers may be equipped with cooling fans, oil pumps or water-cooler
heat exchangers design to remove heat. Power used to operate the cooling system is typically
considered part of the losses of the transformer.
8.6 INSTRUMENT TRANSFORMER
To transform currents and voltages from a usually high value to a value easy to handle for relays
and instruments
To insulate the metering circuit from primary high voltage
To provide possibilities of standardizing the instruments and relays to a few rated currents and
voltages

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8.6.1 CURRENT TRANSFORMER
It is used to measure AC current. It produces an AC in its secondary which is proportional to AC
current it its primary. They are series connected.
8.6.2 POTENTIAL TRANSFORMER
They are parallel connected. They are designed to present negligible load to the supply being
measured and have an accurate voltage ratio and phase relationship to enable accurate secondary
connected metering.
8.7 CAPACITOR VOLTAGE TRANSFORMER (CVT)
It is a transformer used in power system to step down extra high voltage signals and provide low
voltage signals for metering for operating a relay. In its most basic form the device consists of
three parts:
Two capacitors across which the transmission lines signal is split, an inductive element to tune
the device to the line frequency, and a voltage transformer to isolate and further step down the
voltage for metering devices or protective relays. These two capacitors reduce the voltage and
thus the size.
Fig8.7 CVT
8.8 LIGHTNING ARRESTOR
It is a device used on electric power systems and tele-communication systems to protect the
insulation and conductors of the system from damaging effects of lightning. The typical lightning
arrestor has a high voltage terminal and ground terminal. When a lightning surge travels along
the power line to the arrestor, the current from the surge id diverted through the arrestor, in most
cases on earth.
8.9 SWITCHGEAR
It makes or breaks an electrical circuit.

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8.9.1 ISOLATION
A device which breaks an electrical circuit when circuit is switched on to no load. Isolation is
normally used in various ways for purpose of isolating a certain portion when required for
maintenance.
8.9.2 SWITCHING ISOLATION
It is capable of doing things like interrupting transformer magnetized current, interrupting line
charging current and even perform load transfer switching. The main application of switching
isolation is in connection with transformer feeders as unit makes it possible to switch out one
transformer while other is still on load.
8.9.3 CIRCUIT BREAKERS
One which can make or break the circuit on load and even on faults is referred to as circuit
breakers. This equipment is the most important and is heavy duty equipment mainly utilized for
protection of various circuits and operations on load. Normally circuit breakers installed are
accompanied by isolators
8.9.4 LOAD BREAK SWITCHES
These are those interrupting devices which can make or break circuits. These are normally on
same circuit, which are backed by circuit breakers.
8.9.5 EARTH SWITCHES
Devices which are used normally to earth a particular system, to avoid any accident happening
due to induction on account of live adjoining circuits. These equipments do not handle any
appreciable current at all. Apart from this equipment there are a number of relays etc. which are
used in switchgear.

38
CHAPTER-9
COAL HANDLING PLANT
9.1 INTRODUCTION
Objective of CHP is to supply the quanta of processed coal to bunkers of coal mine for boiler
operation and to stack the coal to coal storage area.
Coal is a dark black or dark brown sedimentary rock formed by decomposition of plants
material, widely used as fuel. A piece of coal is called coal lumps. Mostly E and F grade coal is
used in India. There are major five ways for transportation of coal:
1. Roadways
2. Railways
3. Waterways
4. Airways
5. Ropeways
The size of coal lumps are about 600mm. this coal is fed to rotary crusher and after that the size
become 300mm. the coal is further crushed till we get about 20mm lumps. Then this is fed to
coal mills for the process of pulverization. Even when the bunker is full this coal is used for
stacking or storage of coal in coal storage area.
CHP is the plant which handles the coal from its receipt to transport it to boiler and store in
bunker. It also processes the raw coal to make it suitable for boiler operations.
In brief we can say that receipt of coal from coal mines, weighing of coal, crushing it to require
size and transferring the quantity of coal to various coal mill bunkers.
Main targets:
1. To receive, process, store and feed coal.
2. Bunkering of coal
3. Unloading of coal wagon
4. Stacking of coal
9.2 CONSTITUENTS OF COAL
1. Carbon: 42.9%
2. Hydrogen: 2.96%
3. Nitrogen: 0.91%
4. Sulfur: 0.33%

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Around 600 tons of coal is consumed per day to feed the five machines (3 of 95MW and 2 of
210MW) at the Badarpur Thermal Power Station.
9.3 SECTIONS OF CHP
9.3.1 MANAGEMENT OF COAL
Coal is managed in in India by Government, CIL, WCL, Railways etc. For transportation of
coal, roadways, ropeways are not used much as they costlier. The coal is transported mainly by
railways and is unloaded with the help of Wagon Tippler. One rack consists of 52-56 Wagons.
Each wagon consists 55-58MT of coal. Wagon movements are controlled by ‘Bettle chargers’.
Wagon Tippler are of two types:
1. Side Tippler and
2. Rotary Tippler
9.3.2 TRANSPORTATION OF COAL
9.3.3 HANDLING OF COAL
9.4 EQIPMENTS USED IN CHP
9.4.1 PULL CHORD SWITCH
A series of such switches are arranged in section series at a 1m distance on the side of conveyor
belt. The power supply to the rotor of conveyor belt is established only if all series switches are
connected. It is manually reset type placed at spacing of 20m.
Fig9.1 Pull Chord Switch
9.4.2 VIBRATING FEEDER
The coal stored in a huge hub is collected on the belt through vibrations created by vibrating
feeder.

40
Fig9.2 Vibrating Feeder
9.4.3 FLAP GATES
These are used to channelize the route of coal through another belt in case the former is broken
or unhealthy. The flap gates open to let the coal pass and if closed, stop its movement.
9.4.4 MAGNETIC SEPERATOR
These are used to separate the ferrous impurities from the coal.
9.4.5 BELT WEIGHTIER
It is used to keep an account on the tension on the belt carrying coal and moves according to
release tension on the belt.
9.4.6 RECLAIM HOPPER
Reclamation is the process of taking coal from the dead storage for preparation or further feeding
to reclaim hoppers. This is accomplished by belt conveyors.
9.4.7 METAL DETECTORS
These detect the presence of any ferrous or non-ferrous metals in the coal and send a signal to
thee relays which closes to seize the movement of belt until the metal is removed. It basically
consists of transmitter and receiver.
Fig9.3 Metal Detector
9.4.8 SWAY SWITCH

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This switch is of self-resulting type and it shall be provided at a spacing of 45m to limit belt
sway to permissible extent.
Fig9.4 Sway Switch
9.4.9 ZERO SPEED SWITCH
The switch is non-contact (proximity) type electronic switch.
Fig9.5 Zero Speed Switch
9.4.10 CHUTE BLOCKAGE SWITCH
It is provided at suitable height on each leg of the conveyors. This switch shall trip the feeding in
case of chute blockage and protect the feeding conveyor equipment.
9.4.11 WAGON TIPPLER
Wagons from the coal yard come to the tippler and are emptied here. The process is performed
by a slip –ring motor of rating: 55 KW, 415V, 1480 RPM. This motor turns the wagon by 135
degrees and coal falls directly on the conveyor through vibrators. Tippler has raised lower
system which enables is to switch off motor when required till is wagon back to its original
position. It is titled by weight balancing principle. The motor lowers the hanging balancing
weights, which in turn tilts the conveyor. Estimate of the weight of the conveyor is made through
hydraulic weighing machine.

42
Fig9.6 Wagon Tippler
9.4.12 CONVEYOR
There are 14 conveyors in the plant. They are numbered so that their function can be easily
demarcated. Conveyors are made of rubber and more with a speed of 250-300m/min. Motors
employed for conveyors has a capacity of 150 HP. Conveyors have a capacity of carrying coal at
the rate of 400 tons per hour. Few conveyors are double belt, this is done for imp. Conveyors so
that if a belt develops any problem the process is not stalled. The conveyor belt has a switch after
every 25-30 m on both sides so stop the belt in case of emergency. The conveyors are 1m wide, 3
cm thick and made of chemically treated vulcanized rubber. The max angular elevation of
conveyor is designed such as never to exceed half of the angle of response and comes out to be
around 20 degrees.
Fig9.7 Conveyor Belt
9.4.13 CRUSHER
Both the plants use TATA crushers powered by BHEL. Motors. The crusher is of ring type and
motor ratings are 400 HP, 606 KV. Crusher is designed to crush the pieces to 20 mm size i.e.
practically considered as the optimum size of transfer via conveyor.
9.4.14 ROTATORY BREAKER
10 OCHP employs mesh type of filters and allows particles of 20mm size to go directly to RC
bunker, larger particles are sent to crushes. This leads to frequent clogging. NCHP uses a
technique that crushes the larger of harder substance like metal impurities easing the load on
the magnetic separators.

43
9.5 MILLING SYSTEM
9.5.1 RC Bunker
11 Raw coal is fed directly to these bunkers. These are 3 in no. per boiler. 4 & ½ tons of coal
are fed in 1 hr. the depth of bunkers is 10m.
9.5.2 RC Feeder
It transports pre crust coal from raw coal bunker to mill. The quantity of raw coal fed in mill
can be controlled by speed control of aviator drive controlling damper and aviator change.
9.5.3 Ball Mill
The ball mill crushes the raw coal to a certain height and then allows it to fall down. Due to
impact of ball on coal and attraction as per the particles move over each other as well as
over the Armor lines, the coal gets crushed. Large particles are broken by impact and full
grinding is done by attraction. The Drying and grinding option takes place simultaneously
inside the mill.
9.5.4 Classifier
It is an equipment which serves separation of fine pulverized coal particles medium from
coarse medium. The pulverized coal along with the carrying medium strikes the impact
plate through the lower part. Large particles are then transferred to the ball mill.
9.5.5 Cyclone Separators
It separates the pulverized coal from carrying medium. The mixture of pulverized coal
vapour caters the cyclone separators.
9.5.6 The Tturniket
It serves to transport pulverized coal from cyclone separators to pulverized coal bunker or to
worm conveyors. There are 4 turnikets per boiler.
9.5.7 Worm Conveyor
It is equipment used to distribute the pulverized coal from bunker of one system to bunker
of other system. It can be operated in both directions.
9.5.8 Mills Fans
It is of 3 types:
Six in all and are running condition all the time.

44
9.6 CONVEYOR SYSTEM
It consists of:
9.6.1 Conveyor belts
It constitutes of rubber with cotton threads or fiber threads or steel wires. It can be 4-ply, 5-ply or
6-ply rating.
9.6.2 Idlers
It consists of three rollers. Rollers are fitted with bearing. Profile makes an arc on a circle to
avoid sharp bends to increase belt life.
9.6.3 Pulleys
These are of heavy cast irons. Driving pulleys are faced with or similar frictional materials. The
diameter of pulleys is large enough to reduce belt stresses. Width of pulleys is 150mm more than
belts. Snub pulleys are used to relieve load on adjacent return idlers and to increase arc of contact
with the main pulley avoiding belt slipping.

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CHAPTER-10
CONTROLAND INSTRUMENTATION
10.1 INTRODUCTION
Control and instrumentation consists of three divisions i.e. turbine, boiler and off site.
10.2 OFF SITE
It consists of three parameters: WTP, Parameter measuring instrument and SWAS (steam water
analysis system)
10.2.1 PARAMETERS
The parameters that are measured in the above three test are:
10.2.1.1 Conductivity (G)
We know G= 1/R
c = g/R g= d/a (g= cell constant)
10.2.1.2 pH
pH of water is supposed to be in the range of 8-10. If pH decreases the reactivity increases.
pH= (-) logarithmic of H+
10.2.1.3 Silica
If pressure in turbine decreases, the solubility decreases hence the silica content decreases. This
causes vibration in turbine.
10.2.1.4 Dissolved Oxygen (DO)
The amount of oxygen dissolved is checked in boiler drum.
10.2.1.5 Chlorine
Presence of chlorine causes clouding of water.
10.2.1.6 Hydrazine
The dissolved oxygen content decreases due to presence of hydrazine.
10.2.1.7 Oxidation Reduction Process (ORP)

46
It tells about the disinfected present in water.
10.2.1.8 Na+ (Sodium ion)
It is determined by electrolysis process only
10.2.2 PROCESS
There are two major processes for calibration of above parameters.
10.2.2.1 Optical method
Monochromatic light is incident on the sample and then the amount/intensity of light received is
measured. This is known as absorbance. Log (Pi/Po) = Absorbance
10.2.2.2 Electrochemical method
The electrodes are dipped in the sample. The sample acts as electrolyte and voltage is applied to
the electrodes. Here glass electrodes are used and the current is measured. Current is directly
proportional to conductivity of sample. The glass electrodes have KCl solutions which activates
the reaction.
10.3 FLOW MEASUREMENT
There are three methods for flow measurement:
10.3.1 Electro-Magnetic flow measurement
It follows faraday’s law. Due to the change in pressure of flow, emf is generated. The system is
supplied with a 24V supply and is connected to a pressure gauge. Therefore, emf is directly
proportional to velocity.
10.3.2 Differential pressure
Pressures across the two points are noted and hence ∆P is calculated in terms of I.
F=√∆P
10.3.3 Turbine/Turbo Flow meter
Here transducers are used to measure flow such as LVDT and capacitive. A pickup sensor is
attached to the system; pressure is directly proportional to velocity.
10.4 LEVEL MEASUREMENT
Level can be measured by following three methods:
10.4.1 R.F. LEVEL

47
Transmit time ∆t=t2-t1; ∆t is directly proportional to level.
10.4.2 ULTRA SONIC WAVE LEVEL
This is used in acid tank. It is used in LDO (Light Diffused Oil) motors or ash slurry tank.
10.4.3 DIFFERENTIAL PRESSURE
P=Hδg, P1 is directly proportional to H1. Hence, P2-P1 is directly proportional to H2-H1 (level).
10.5 C.E.M.S.
Continuous mission Monitoring System is used to measure SOx, NOx, CO, CO2, etc.
10.6 A.Q.M.S.
Air Quality Measurement System measures SOx, NOx, CO, CO2, O3, PM10, PM2.5, etc.
10.7 OPACITY
It tells about the opaqueness of flue gases. It should be less than 40mg/Nm3.
Transmitivity= log (Po/Pi)
Opacity= (1- Transmitivity) x 100%
T= T12 x T21
Where T12=Dn/Dt x a12 and T21=Dm/Dt x a21
Conductivity of water is around 500-600 during rainy season while 1400-1600 in general days.

48
CHAPTER-11
WATER TREATMENT
11.1 INTRODUCTION
The water from source is treated in 4 steps. Every step has 4 designated tanks at BTPS.
11.2 PRESSURE FILTER TANK
These tanks consist of stone due to which the sand settles. This decreases the turbidity of the feed
water and chlorine is added to kill germs.
11.3 ACTIVE CHLORINE FILTER
It has a bed of burnt wood (charcoal type). Here the chlorine is absorbed.
11.4 ANION TANK
Here the negative ions are removed.
11.5 CATION TANK
Resins acts as filter in this tank and hence positive ions are removed.
11.6 STORAGE BASED TANK
This tank is used to decrease conductivity of water.
11.7 MIXED BED TANK
From this tank we obtain Demineralized (D.M.) Water. In this bed, all the positive and negative
ions are removed and pH is balanced around 7-8 and conductivity around 0.3-0.5 but practically
around 1.1 to 1.2.

50
CHAPTER-12
INSTRUMENTATION
12.1 TEMPERATURE
Devices used are:
12.1.1 R.T.D. (Resistance Temperature Detector)
Pt-100 is used in this device and it is used for temperature up to 100⁰C. this device is more
sensitive (Ω/⁰C)
12.1.2 THERMOCOUPLE
This device utilizes the seeback effect between the two dissimilar metals. The metals used are k-
type chromal and alumal metals. It can be operated up to 1320⁰C.
12.1.3 TEMPERATURE GAUGE
It is used at local site. It measure degree change in voltage with respect to temperature (mV/⁰C).
12.1.4 TEMPERATURE SWITCH
It is used for alarm and protection of the devices in the given range.
12.2 PRESSURE
A capacitor with one fixed plate and one moving plate is used. Pressure is applied on the
moving plate. C=ԑoA/d, generally the scale is 4-20mA 0-10 bar.
12.2.1 PRESSURE GAUGE
Bourdon tube is used in this. It is used in local site measurement.
12.2.2 PRESSURE SWITCH
This device is used for alarm and protection.
12.3 FLOW
4 to20mA which is directly proportional to differential pressure. Flow is directly proportional to
√D.P. also emf is directly proportional to flow.
12.4 LEVEL

51
P=hdg.
Level 0 (DP)max , (level)max (D.P.)min Hence 4mA (level)max and 20mA (level)min
12.4.1 HYDRASTEP MANAGEMENT
This is used to measure the amount of water and steam in boiler. There are two drum levels (L
and R) each has 14 no. of LEDs. These LED turn green when they detect water and turn red
when they detect steam/air. This is used to measure the level of water in the drum.
12.4.2 RADAR TYPE TRANSMITTER
It utilizes the reflection time measurement techniques. The signal touches the level or surface of
water/sample & gets reflected back. The time taken is used to calculate level.
12.4.3 SPECIAL ANALYZER
1. O2 measurement: Zirconia Probe is used for this
2. CO measurement: Transmitter and receiver circuit is used.
3. SOx, NOx, CO2 measurement: AQMS is used.
12.5 S.P.M. Measurement
It is a kind of opacity meter installed at the chimneys from where air is outlet. Opacity of the air
should be less than 50 pp/m2. For reducing opacity Electrostatic Precipitator is used which
attracts the charged particles and cleanses the air from dust and other particles.
Fig12.1 Control panel

52
CHAPTER-13
GENERATORAND AUXILIARIES
13.1 INTRODUCTION
The transformation of mechanical energy into electrical energy is carried out by the Generator.
This Chapter seeks to provide basic understanding about the working principles and development
of Generator.
13.2 WORKING PRINCIPLE
The A.C. Generator or alternator is based upon the principle of electromagnetic induction and
consists generally of a stationary part called stator and a rotating part called rotor. The stator
housed the armature windings. The rotor houses the field windings. D.C. voltage is applied to the
field windings through slip rings. When the rotor is rotated, the lines of magnetic flux (viz
magnetic field) cut through the stator windings. This induces an electromagnetic force (e.m.f.) in
the stator windings. The magnitude of this e.m.f. is given by the following expression.
E = 4.44 /O FN volts
0 = Strength of magnetic field in Weber’s.
F = Frequency in cycles per second or Hertz.
N = Number of turns in a coil of stator winding
F = Frequency = Pn/120
Where P = Number of poles
n = revolutions per second of rotor.
From the expression it is clear that for the same frequency, number of poles increases with
decrease in speed and vice versa. Therefore, low speed hydro turbine drives generators have 14
to 20 poles where as high speed steam turbine driven generators have generally 2 poles. Pole
rotors are used in low speed generators, because the cost advantage as well as easier
construction.
13.3 DEVELOPMENT
The first A.C. Generator concept was enunciated by Michael Faraday in 1831. In 1889 Sir
Charles A. Parsons developed the first AC turbo-generator. Although slow speed AC generators
have been built for some time, it was not long before that the high-speed generators made its
impact.
Development contained until, in 1922, the increased use of solid forgings and improved
techniques permitted an increase in generator rating to 20MW at 300rpm. Up to the out break of

53
second world war, in 1939, most large generator;- were of the order of 30 to 50 MW at 3000
rpm.
During the war, the development and installation of power plants was delayed and in order to
catch up with the delay in plant installation, a large number of 30 MW and 60 MW at 3000 rpm
units were constructed during the years immediately following the war. The changes in design in
this period were relatively small.
In any development programme the. Costs of material and labour involved in manufacturing and
erection must be a basic consideration. Coupled very closely with
these considerations is the restriction is size and weight imposed by transport limitations.
Development of suitable insulating materials for large turbo-generators is one of the
most important tasks and need continues watch as size and ratings of machines
increase. The present trend is the use only class "B" and higher grade materials and
extensive work has gone into compositions of mica; glass and asbestos with
appropriate bonding material. An insulation to meet the stresses in generator slots must
follow very closely the thermal expansion of the insulated conductor without cracking or
any plastic deformation. Insulation for rotor is subjected to lower dielectric stress but
must withstand high dynamic stresses and the newly developed epoxy resins, glass
and/or asbestos molded in resin and other synthetic resins are finding wide
applications.
13.4 GENERATOR COMPONENT
This Chapter deals with the two main components of the Generator viz. Rotor, its winding &
balancing and stator, its frame, core & windings.
13.4.1 ROTOR
The electrical rotor is the most difficult part of the generator to design. It revolves in
most modern generators at a speed of 3,000 revolutions per minute. The problem of
guaranteeing the dynamic strength and operating stability of such a rotor is complicated
by the fact that a massive non-uniform shaft subjected to a multiplicity of differential
stresses must operate in oil lubricated sleeve bearings supported by a structure
mounted on foundations all of which possess complex dynamic be behavior peculiar to
themselves. It is also an electromagnet and to give it the necessary magnetic strength
the windings must carry a fairly high current. The passage of the current through the
windings generates heat but the temperature must not be allowed to become so high,
otherwise difficulties will be experienced with insulation. To keep the temperature down,
the cross section of the conductor could not be increased but this would introduce
another problems. In order to make room for the large conductors, body and this would
cause mechanical weakness. The problem is really to get the maximum amount of
copper into the windings without reducing the mechanical strength. With good design
and great care in construction this can be achieved. The rotor is a cast steel ingot, and

54
it is further forged and machined. Very often a hole is bored through the centre of the
rotor axially from one end of the other for inspection. Slots are then machined for
windings and ventilation.
Fig13.1 Generator
13.4.2 ROTOR WINDING
Silver bearing copper is used for the winding with mica as the insulation between conductors. A
mechanically strong insulator such as micanite is used for lining the slots. Later designs of
windings for large rotor incorporate combination of hollow conductors with slots or holes
arranged to provide for circulation of the cooling gas
through the actual conductors. When rotating at high speed. Centrifugal force tries to lift
the windings out of the slots and they are contained by wedges. The end rings are
secured to a turned recess in the rotor body, by shrinking or screwing and supported at
the other end by fittings carried by the rotor body. The two ends of windings are connected to
slip rings, usually made of forged steel, and mounted on insulated
sleeves.
13.4.3 ROTOR BALANCING
When completed the rotor must be tested for mechanical balance, which means that a
check is made to see if it will run up to normal speed without vibration. To do this it
would have to be uniform about its central axis and it is most unlikely that this
will be so to the degree necessary for perfect balance. Arrangements are therefore
made in all designs to fix adjustable balance weights around the circumference at each
end.
13.4.4 STATOR
13.4.4.1 Stator frame

55
The stator is the heaviest load to be transported. The major part of this load is the stator core.
This comprises an inner frame and outer frame. The outer frame is a rigid fabricated structure of
welded steel plates, within this shell is a fixed cage of girder built circular and axial ribs. The ribs
divide the yoke in the compartments through which hydrogen flows into radial ducts in the stator
core and circulate through the gas coolers housed in the frame. The inner cage is usually fixed in
to the yoke by an arrangement of springs to dampen the double frequency vibrations inherent in
2 pole generators. The end shields of hydrogen cooled generators must be strong enough to carry
shaft seals. In large generators the frame is constructed as two separate parts. The fabricated
inner cage is inserted in the outer frame after the stator core has been constructed and the
winding completed.
13.4.4.2 Stator core
The stator core is built up from a large number of 'punching" or sections of thin steel plates. The
use of cold rolled grain-oriented steel can contribute to reduction in the weight of stator core for
two main reasons:
a) There is an increase in core stacking factor with improvement in lamination cold
Rolling and in cold buildings techniques.
b) The advantage can be taken of the high magnetic permeance of grain-oriented
steels of work the stator core at comparatively high magnetic saturation without
fear or excessive iron loss of two heavy a demand for excitation ampere turns
from the generator rotor.
13.4.4.3 Stator Windings
Each stator conductor must be capable of carrying the rated current without overheating. The
insulation must be sufficient to prevent leakage currents flowing between the phases to earth.
Windings for the stator are made up from copper strips wound with insulated tape which is
impregnated with varnish, dried under vacuum and hot pressed to form a solid insulation bar.
These bars are then place in the stator slots and held in with wedges to form the complete
winding which is connected together at each end of the core forming the end turns. These end
turns are rigidly braced and packed with blocks of insulation material to withstand the heavy
forces which might result from a short circuit or other fault conditions. The generator terminals
are usually arranged below the stator. On recent generators (210 MW) the windings are made up
from copper tubes instead of strips through which water is circulated for cooling purposes. The
water is fed to the windings through plastic tubes.
13.4.5 GENERATOR COOLING SYSTEM
The 200/210 MW Generator is provided with an efficient cooling system to avoid excessive

56
heating and consequent wear and tear of its main components during operation. This Chapter
deals with the rotor-hydrogen cooling system and stator water cooling system along with the
shaft sealing and bearing cooling systems.
13.4.6 ROTOR COOLING SYSTEM
The rotor is cooled by means of gap pick-up cooling, wherein the hydrogen gas in the
air gap is sucked through the scoops on the rotor wedges and is directed to flow along
the ventilating canals milled on the sides of the rotor coil, to the bottom of the slot where
it takes a turn and comes out on the similar canal milled on the other side of the rotor
coil to the hot zone of the rotor. Due to the rotation of the rotor, a positive suction as
well as discharge is created due to which a certain quantity of gas flows and cools the
rotor. This method of cooling gives uniform distribution of temperature. Also, this
method has an inherent advantage of eliminating the deformation of copper due to
varying temperatures.
13.4.7 HYDROGEN COOLING SYSTEM
Hydrogen is used as a cooling medium in large capacity generator in view of its high heat
carrying capacity and low density. But in view of its forming an explosive mixture with oxygen,
proper arrangement for filling, purging and maintaining its purity inside the generator have to be
made. Also, in order to prevent escape of hydrogen from the generator casing, shaft sealing
system is used to provide oil sealing.
The hydrogen cooling system mainly comprises of a gas control stand, a drier, an liquid level
indicator, hydrogen control panel, gas purity measuring and indicating instruments,
The system is capable of performing the following functions :
1. Filling in and purging of hydrogen safely without bringing in contact with air.
2. Maintaining the gas pressure inside the machine at the desired value at all the
times.
3. Provide indication to the operator about the condition of the gas inside the
machine i.e. its pressure, temperature and purity.
4. Continuous circulation of gas inside the machine through a drier in order to
remove any water vapour that may be present in it.
5. Indication of liquid level in the generator and alarm in case of high level.
13.4.8 STATOR COOLING SYSTEM
The stator winding is cooled by distillate. Which is fed from one end of the machine by
Teflon tube and flows through the upper bar and returns back through the lower bar of
another slot?

57
Turbo generators require water cooling arrangement over and above the usual hydrogen
cooling arrangement. The stator winding is cooled in this system by circulating
demineralised water (DM water) through hollow conductors. The cooling water used for
cooling stator winding calls for the use of very high quality of cooling water. For this
purpose DM water of proper specific resistance is selected. Generator is to be loaded within a
very short period if the specific resistance of the cooling DM water goes beyond certain
preset values. The system is designed to maintain a constant rate of cooling water flow to the
stator winding at a nominal inlet water temperature of 40 deg.C.
13.5 RATING OF 95 MW GENERATOR
Manufacture by Bharat heavy electrical Limited (BHEL)
Capacity - 117500 KVA
Voltage - 10500V
Speed - 3000 rpm
Hydrogen - 2.5 Kg/cm2
Power factor - 0.85 (lagging)
Stator current - 6475 A
Frequency - 50 Hz
Stator winding connection - 3 phase
13.6 RATING OF 210 MW GENERATOR
Capacity - 247000 KVA
Voltage (stator) - 15750 V
Current (stator) - 9050 A
Voltage (rotor) - 310 V
Current (rotor) - 2600 V
Speed - 3000 rpm
Power factor - 0.85
Frequency - 50 Hz
Hydrogen - 3.5 Kg/cm2
Stator winding connection - 3 phase star connection
Insulation class - B

58
CHAPTER-14
CONCLUSION
Industrial training being an integral part of engineering curriculum provides not only easier
understanding but also helps acquaint an individual with technologies. It exposes an individual to
practical aspect of all things which differ considerably from theoretical models. During my
training, I gained a lot of practical knowledge which otherwise could have been exclusive to me.
The practical exposure required here will pay rich dividends to me when I will set my foot as an
engineer.
All the minor and major sections in the thermal project had been visited and also understood to
the best of my knowledge. I believe that this training has made me well verse with the various
process in the power plant. My training period at thermal power plant also made me realize the
need for new technologies that work on renewable resources as coal and other fossil fuels are
dwindling and thus to supply power to the developing needs of the country we must advance our
skills for a better future.

National Thermal Power Corporation: India's largest power producer

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