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INTRODUCTION
The special plant which is producing bulk
electric power is known as power plant or
generating station.
Depending upon the form of energy converted
into electrical energy generating stations are
classified as:
1.thermal power stations
2.Hydro electric power stations
3.Neuclear power stations
What is HEP
HEP (Hydroelectric Power) is an environmentally
friendly way to generate electricity.
How it works
A dam is built to trap water, usually in a valley where there is
an existing lake.Water is allowed to flow through tunnels
into the dam,to turn turbines and thus drive
generators.Notice that the dam is much thicker at the
bottom than at the top,because the pressure of the water
increases with depth.
Hydroelectric Power Plant
Water
in dam
(P.E.)
Nozzle
(K.E.)
Turbine
(M.E.)
Generator
(Electrical)
Energy conversion in hydroelectric power plant
Anatomy of A Hydroelectric Power Plant
DAM
Dams are structures built over rivers to stop the water flow and form a
reservoir
The reservoir stores the water flowing down the river. This
water is diverted to turbines in power stations.
SPILLWAY
A spillway as the name suggests could be called as a way for
spilling of water from dams. It is used to provide for the
release of flood water from a dam.
It is used to prevent over toping of the dams which could result
in damage or failure of dams
PENSTOCK AND TUNNEL
Penstocks are pipes which carry water from the reservoir to the turbines
inside power station. They are usually made of steel and are equipped
with gate systems. Water under high pressure flows through the penstock.
A tunnel serves the same purpose as a penstock. It is used when an
obstruction is present between the dam and power station such as a
mountain.
SURGE TANK
Surge tanks are tanks connected to the water conductor system. It serves
the purpose of reducing water hammering in pipes which can cause
damage to pipes.
The sudden surges of water in penstock is taken by the surge tank, and
when the water requirements increase, it supplies the collected water
thereby regulating water flow and pressure inside the penstock.
POWER STATION
Power station contains a turbine coupled to a generator. The
water brought to the power station rotates the vanes of the
turbine producing torque and rotation of turbine shaft. This
rotational torque is transferred to the generator and is
converted into electricity.
POWER STATION CONTD
The used water is released through the tail race. The
difference between head race and tail race is called gross head
and by subtracting the frictional losses we get the net head
Advantages
Once the dam is built,the
energy is virtually free
Water can be stored above No waste or pollution
the dam ready to cope
produced
with peaks in demand
Electricity can be
much more reliable than
generated constantly
wind,solar or wave power
Hydro-electric power
stations can increase to
full power very quickly
unlike other power
stations
disadvantages
The dams are very expensive
to build,however many
dams are also used for
flood control or
irrigation,so building costs
can be shared
Building a large dam will
flood a very large area
upstream,causing
problems for animals that
used to live there
Finding a suitable site can be
difficult - the impact on
residents and the
environment may be
unacceptable.
Water quality and quantity
downstream can be
affected, which can have an
impact on plant life.
Hydrological Cycle
Steam power plants
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The generating station which convertes heat energy
of coal combustion into electrical energy is known as
thermal power station .
 Steam is produed in the boiler by utilising the heat of
coal combustion.steam is then expanded in the prime
mover and is then condensed in the condenser to be
fed into the boiler again. The steam turbine drives the
alternator which converts mechanical energy of the
turbine into electrical energy.
Steam power station
Major components of steam power plants are
1.Coal and ash handling plant
2.Steam generating plants(boiler,economiser,super
heater,air preheater)
3.Steam turbine
4.Alternater
5.Feed water
6.Cooling arrangement
 Coal handling system
 it consists of a coal storage unit ,where coal is stored in
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bulk. Clean and dry coal is then transported through
conveyor system for further processing in the crusher
.crushing and pulverization of coal is important to reduce
the size of particles for effective combustion.
Boiler
The heat of combustion of coal is utilised to convert water
into steam at high temperature and pressure.
Super heater
The steam produed in the boiler is wet and is passed
through the superheater where it is dried and superheated
by the flue gases by their way to chimney.
 Economiser
 It extracts a part of heat from the flue gases to increase
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the temperature of feed water before supplying to the
economiser.
Air preheater
It extracts a part of heat from the flue gases to increase
the temperature of air used for coal combustion before
supplying to the boiler.
steam turbine
The dry and superheted steam is fed to the steam
turbine .the heat energy of steam is when passing over
the blades of the turbine is converted into mechanical
enegy(kinetic). After giving heat energy ,the steam is
fed to the condenser .
 Alternator
 The steam turbine is coupled to an alternator. It
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converts mechanical energy of the turbine into
electrical energy .
Feed water
The condensate from the condenser is used as feed
water in the boiler.
Cooling tower
The hot water from the condenser is passed through
the cooling tower where it is cooled
Neuclear power plant
 The schematic diagram of neuclear power plant is
shown in fig.the whole arrangement can be divided
into four main sections
 1.neuclear reactor
 2.heat exchanger
 3.steam turbine
 4.Alternator
neuclear reactor
it is an apparatus in which neuclear fuel like u235
subjected to neuclear fission.it houses the the fuel rod
of uranium ,moderator (graphite rod)and control
rod(cadmium)
.
 Heat exchanger
 The coolant gives up heat to the heat exchanger which
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is utilised in raising the steam.
Steam turbine
The steam produced in the heat exchanger is fed to the
steam turbine .the heat energy of steam is when
passing over the blades of the turbine is converted into
mechanical enegy(kinetic). After giving heat energy
,the steam is fed to the condenser .
Alternator
The steam turbine is coupled to an alternator. It
converts mechanical energy of the turbine into
electrical energy .
 Feed water
 The condensate from the condenser is used as feed
water in the boiler.
 Cooling tower
 The hot water from the condenser is passed through
the cooling tower where it is cooled
 There are two systems of tapping from the mains
 1.tree system
 2.distributed system
In tree system sub circuits are tapped from the main circuits
at some convenient place .now a days this system is out of
practice.
Advantages
The length of the cable required for the installation of wiring
is less. So the initial cost is less .
Disadvantages
Fuses in the installation are scattered and location of the
fault is not easy.
 Voltage available at different points of load will vary.
 Appearance of the system isnot so good.
Distribution system
this system is most commonly used.in this system the main
distribution circuit is brought to one or more distribution
boxes from where it is further distributed to different
branch circuits.
Advantages
1.Fault finding is easy
2.The voltage available at different points of the circuit will be
the same
3.Extension of the circuit is easy
Disadvantages
The length of the cable required for the installation of wiring
is more. So the initial cost is more .
Arrangement of tree system
Grounding/earthing
Enclosure connected to neutral
wire
Ground wire connected to
enclosure
System grounding