1. BASICS OF ELECTRICAL ENGINEERING
GENERATING STATIONS
BASICS OF ELECTRICAL ENGINEERING 1

2. INTRODUCTION Electrical Energy2
Electrical Energy
Considered as the supplier of all other forms of energy
Cheaper than other forms
Economical to use this for domestic, commercial, industrial and agricultural purposes
Easily converted into other forms of energy
Hence, bulk electric power is required.
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3. GENERATING STATIONS Employs a Prime-mover coupled to an alternator3
Employs a Prime-mover coupled to an alternator
Prime-mover converts energy from some other form into mechanical energy
Alternator converts mechanical energy into electrical energy
Electrical energy is transmitted and distributed with the help of conductors to various consumers
Classification of generating stations
Hydro-electric power station
Thermal power station
Nuclear power stations
Diesel power stations
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4. POWER SCENARIO IN INDIA4
Total installed capacity 150,000MW
Hydropower 50,000 MW
Nuclear 10,000MW
Thermal (fossil fuels) 80,000MW
Other methods 10,000MW
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5. SCHEMATIC ARRANGEMENT5
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6. SCHEMATIC ARRANGEMENT6
Artificial storage reservoir formed by constructing a dam across a river and a pressure tunnel is taken off from the reservoir to the valve house at the start of the penstock
Valve house contains main sluice valves for cutting off water flow to the power station and isolating valves for cutting off water supply in case of penstock bursts (automatic)
Surge tank for better regulation of water pressure in the system (provided just before the valve house)
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7. SCHEMATIC ARRANGEMENT7
Explanation
Reservoir – water – valve house – through – pressure tunnel and from valve house to the water turbine – through pipes of large diameter made of steel or reinforced concrete, called penstock
Water turbine – converts – hydraulic energy into mechanical energy
Alternator coupled to water turbine – converts – mechanical energy to electrical energy
Water – after useful work – discharged to tailrace
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8. ADVANTAGES No fuel is required. Hence operating costs are low8
No fuel is required. Hence operating costs are low
Highly reliable and cheap in operation and maintenance
Very neat and clean plant – no smoke or ash is produced
Robust and have got longer life
Highly skilled engineers are required for construction, but, few experienced persons are required later on
Useful for irrigation and flood control
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9. DISADVANTAGES It requires large area9
It requires large area
Construction cost is high, requires long time for erection
Long transmission lines are required – since plants are located in hilly areas
Uncertainty about availability of water – depends on weather condition
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10. THERMAL STATIONS [STEAM POWER PLANT]10
Heat of combustion of fuels (Coal, Oil or Gas) is utilized by boilers to raise the steam at high pressure and temperature
Steam produced is used in driving the steam turbines coupled to generators and thus in generating electrical energy
Steam generated is also used for industrial purposes such as in paper mills, textile mills, sugar mills and refineries, chemical works, breweries, plastic manufacture, food manufacture
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11. SCHEMATIC ARRANGEMENT11
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12. SCHEMATIC ARRANGEMENT12
FUEL AND ASH CIRCUIT
Fuel from storage is fed to the boiler through fuel feeding device. Ash – due to combustion of coal collects at the back of the boiler and is removed to ash storage through ash handling equipment
AIR AND FUEL GAS CIRCUIT
Air drawn from atmosphere – forced draught fan through air pre-heater – heated by heat of flue gases passing to chimney – admitted to the furnaces. Flue-gases – passing through the boiler tubes and super heater tubes – drawn by the induced draught fan through dust collector economizer and air pre-heater – finally – exhausted to the atmosphere through chimney
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13. SCHEMATIC ARRANGEMENT13
FEED WATER AND STEAM CIRCUIT
Condensed water – extracted from the condenser by the condenser pump – forced to the I.P. feed water heater, where its temperature is raised by the heat from bled steam.
Feed water – now pumped to high pressure water heater – gets heated by the heat from bled steam extracted at suitable point of steam turbine – then pumped into boiler through economizer – further heated by the heat of flue gases.
Boiler – water is converted to high pressure wet steam.
Wet steam – through super heater – dried and superheated – supplied to the steam turbine through main valve – then – exhausted to the condenser and converted to feed water
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14. SCHEMATIC ARRANGEMENT14
COOLING WATER CIRCUIT
Cooling water – supplied from a natural source of supply – river, canal, sea or cooling towers – circulated through the condenser for condensing the steam and finally discharged to the suitable position near the source of supply
Circulation of cooling water – helps – maintaining a low pressure in the condenser
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15. ADVANTAGES Fuel used is cheaper15
Fuel used is cheaper
Less space is required in comparison with that of hydro-electric plants
Cheaper in initial cost in comparison with other types of power plants of same capacity
Cheaper in production cost in comparison with that of diesel power plant
Can be installed in any place
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16. DISADVANTAGES High maintenance and operating costs16
High maintenance and operating costs
Pollution of atmosphere due to fumes and residues from pulverized fuels
Requirement of water in huge quantity
Handling of coal and disposal of ash is quite difficult
Requires long time for erection and put into action
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17. NUCLEAR POWER PLANTS Peaceful application of atomic energy17
Peaceful application of atomic energy
First atomic power plant – commissioned in U.S.S.R on June 27, 1954 and after that a number of atomic power plants have been commissioned in many countries like U.S.A., Canada, Great Britain, Japan and France
First Atomic power plant in India – located in Tarapore
Nuclear energy is converted into electrical energy
Main atomic fuels – Uranium and Thorium
In reactor heat energy released from reactor is utilized in raising steam at high temperature and pressure – which drives the steam turbine and convents steam energy into mechanical energy and then alternator converts it into electrical energy.
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18. SCHEMATIC ARRANGEMENT18
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19. SCHEMATIC ARRANGEMENT19
EXPLANATION
Nuclear power plant consists of
Nuclear reactor – for heat generation
Heat exchanger – for converting water into steam
Steam turbine
Alternator
Condenser
Reactor and cooling circuit have to heavily shielded to eliminate radiation hazards
Heat energy produced – breaking of atoms of Uranium by fission process – atomic reactor – extracted by – pumping fluid or molten metal like liquid sodium or gas through the pile
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20. SCHEMATIC ARRANGEMENT20
Heated metal/gas – allowed to exchange its heat to the heat exchanger by circulation
Steam produced in the heat exchanger is utilized to drive the turbine
Turbine – drives the alternator – which converts mechanical energy into electrical energy
Output from alternator – delivered to the bus bars through transformer, circuit breakers and isolators
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21. ADVANTAGES 21
The amount of fuel required is quite small, therefore, there is no problem of transportation, storage etc.
These plants need less area as compared to any other type
These plants can be located near the load centers, therefore, primary distribution cost is reduced
These plants are most economical in large quantity
There are large deposits of nuclear fuels available all over the world. Such plants can ensure continued supply of electrical energy for thousands of years
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22. DISADVANTAGES 22
The initial capital cost is very high as compared to other types of power plants
The erection and commissioning of the plant requires greater technical knowledge
The fission by products are generally radio-active and may cause a dangerous amount of radio-active pollution
The fuel used is expensive
The disposal of the products (radio-active) – either to be disposed off in a deep trench or in a sea away from sea-shore
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