Science F3 C8-PPT-Part I Dynamo and Generator

http://xinhuicafe.wordpress.com

GENERATION OF ELECTRICITYScience Form 3 Chapter 8

Last update: 4/8/2010


Part I Generation of Electrical Energy

F3 C8 GENERATION OF ELECTRICITY


A. Principle of Dynamo

• A dynamo is used to produced electrical energy



• A dynamo consist of a coil of wire suspended in a magnetic field

• When the coil of wire is spun, it cuts the magnetic field lines and electrical energy is generated in the coil

• The electrical energy in the coil is transmitted for use such as for lighting and heating



• The energy change which takes place in a dynamo is as follows:

• Every power station has a large dynamo or generator to produce electrical energy

Kinetic E. Electrical E.


Types of generator

Thermal generator

Hydroelectric generator

Gas turbine generator

Diesel generator

Nuclear generator


(a) Thermal Generator



• A thermal power station usually uses coal, diesel or natural gas as a fuel to boil water in a large boiler

• Steam under high pressure is channeled to turn a turbine

• The turbine drives a dynamo which produces electrical energy



Chemical E. (Fuel)

Heat E. (fire)

Potential E. (Steam

under Pressure)

Kinetic E. (Spinning turbine

and dynamo)

Electrical E.

(produced by

dynamo)



• After turning the turbine, steam is condensed by a condenser into water and is returned to the boiler

• Thermal generators are usually located near petroleum refineries or coal mines so that fuel is easily obtained.

• Port Klang, Port Dickson and Seberang Prai have thermal generators.


(b) Hydroelectric Generator



• A dam is built across a river to collect water in a high reservoir

• The water is channeled through a tunnel to spin a turbine

• The turbine spins a dynamo which produces electrical energy



Potential E. (Water at a height)

Kinetic E. (Spinning turbine and dynamo)

Electrical E. (produced by dynamo)



• A hydroelectric power station can be built where there is a river with a continuous flow of water

• The reservoir can be used for:– Controlling floods– Irrigating paddy fields– Fish rearing



• Hydroelectric power stations are used in:– Chenderoh, Perak– Cameron Highlands, Pahang– Kenyir, Terengganu

• Many hydroelectric power stations have been built in Malaysia. Why?


(c) Gas turbine Generator



• A gas turbine generator burns a mixture of gas and air to turn a dynamo for producing electrical energy.

• Air is sucked in, filtered and compressed by a compressor

• The compressed air is mixed with the fuel gas• The mixture of air and gas is ignited by a spark plug

in the combustion chamber.• The ignited mixture burns and expands with great

force. This turns the turbine which then turns the dynamo to produce electrical E.


(c) Gas Turbine Generator

Chemical E. (Gas)

Heat E. (fire)

Potential E. (High pressure

gas expanding)


and dynamo)

Electrical E.

(produced by

dynamo)



• Gas turbine generators are not efficient because a lot of energy is lost in the form of heat during the generation process.

• Gas turbine generators are usually situated in places where the fuel gas is easily obtained.

• The power station in Paka (Terengganu) uses gas turbine generators.


(d) Diesel Generator



• A diesel generator is used to supply electrical energy to a small place such as a village or an amusement park

• The diesel engine is similar to that used in a diesel engine car

• The diesel burning in the engine produces a great expanding force

• This expanding force drives a piston which in turn drives a dynamo for producing electrical energy



Chemical E. (Diesel)

Heat E. (fire)

Potential E.

(Expanding hot gas)

Kinetic E. (Piston

and dynamo)

Electrical E.

(produced by

dynamo)



• Diesel generators are used in Bukit Larut (Taiping) and Bukit Fraser


(e) Nuclear Generator



• Nuclear fuel is also used to generate electrical energy

• Nuclear energy is produced in a reactor by splitting uranium atoms

• The heat from the nuclear energy is used to boil water to obtain steam

• Steam under high pressure is used to spin a turbine, which in turns drives a dynamo

• The dynamo produces electrical energy



Chemical E.

(Uranium)

Nuclear E.

(Released by

splitting uranium

atom)

Heat E. (fire)

Potential E.

(Steam under

Pressure)


and dynamo)

Electrical E.

(produced by

dynamo)



• The steam used to turn the turbine is condensed into water again by a condenser and returned to the boiler

• Many people are against the use of nuclear energy to generate electricity because of the possibility of accidents

• Accidents involving nuclear energy and radioactive substances are hazardous and life threatening

• Great care must taken when using nuclear energy


Alternative Sources of Energy

• Solar• Wind• Geothermal• Biomass• Tides


(a) Solar

• Free, does not pollute the environment• Disadvantage: not available at night


(b) Wind• Countries such as Holland and Canada use

wind turbines which are driven by wind.• Wind turbines do not pollute the

environment, except that they may spoil the natural scenery


(c) Geothermal

• Geothermal E. is heat E. obtained from the interior of the earth.

• Commonly used to heat boilers to supply steam for warming houses and factories in cold countries.


(d) Biomass

• Biomass consist of organic waste• Biomass can be used to produce fuels such as

methane and alcohol• The residue can be turned into fertilisers


(e) Tides

• Tides can be used to turn turbines and dynamos

• This method is not very effective and not reliable. The tide flow in and out from the shore only twice a day

Science F3 C8-PPT-Part I Dynamo and Generator

Documents

Transcript of Science F3 C8-PPT-Part I Dynamo and Generator