science f3 c8-ppt-part iii transmission and distribution of electricity

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GENERATION OF ELECTRICITYScience Form 3 Chapter 8

Last update: 4/8/2010


Part III System For Transmission and

Distribution of ElectricityF3 C8 GENERATION OF ELECTRICITY


The National Grid Network

• The National Grid Network is a network of cables connecting all the power stations in the country.

• The cables are made of copper or aluminium. Both these metals are good conductors of electricity.



• Main advantages of the network– Any area requiring additional electrical energy can be

supplied by an additional power station in the network– The function of a power station which has stopped for

repairs can be taken over by another power station in the network

– Some power stations can be closed when the demand of electrical energy is low. This saves running costs.

– With this network, very large power stations are not necessary.



• The electrical energy is transmitted by overhead or underground cables.

Overhead cables Underground cables

Advantages• Easy for repair work• Cheaper

Disadvantages• Pose a danger to the consumers• Spoil the natural scenery

Advantages• No danger to the consumer•Do not spoil the natural scenery

Disadvantages• More difficult to carry out repair work• Higher costs for laying the cables


Transmission and Distribution of Electricity



• Power Station• Step-up Transformer• Switch zone• National Grid Network• Main substations and

branch substations



• Power Station– The electrical energy is sent

out at a very high voltage with a low A.C

– An AC is used because its voltage can be stepped up or stepped down easily

– A low current is used because it generates less heat in the cable

• Step-up Transformer• Switch zone• National Grid Network• Main substations and branch substations



• Power Station

• Step-up Transformer– It raises the voltage

from the power station from 11kV to 132kV

– The electrical energy is directly into a switch zone

• Switch zone• National Grid Network• Main substations and branch

substations



• Power Station• Step-up Transformer

• Switch zone– It channels the electrical

energy into the national grid network

– Can be opened or closed to activate or deactivate specific electrical power transmissions leaving the power station

• National Grid Network• Main substations and branch substations



• Power Station• Step-up Transformer• Switch zone

• National Grid Network– This network links all the

main power stations in the country

– If necessary, the supply to an area can be increased or decreased

• Main substations and branch substations



• Power Station• Step-up Transformer• Switch zone• National Grid Network

• Main substations and branch substations– At each substation, a step-down

transformer lowers the main voltage to a desirable level

– At the main substation, the voltage is stepped down to 11kV or 33kV

– The voltage applied to factories is usually set at 415V

– The voltage for houses is set a 220-240V


TNB Substation (step-down transformer)

science f3 c8-ppt-part iii transmission and distribution of electricity

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