Transmission and distribution of electricity:
Source: Western Power’s World of Energy.
 To view the interactive transmission and distribution diagram - click here.
Electricity provides an economical and convenient way to move energy from a source (coal, oil, natural gas, water, wind) to the place where it is needed - your place, the school, shops, factories. The electric current can be converted into mechanical energy (to help drive your electric drill) or heat energy (to power your electric room heater).
It is this ease of transmission and distribution of electrical energy which has helped to make it so popular and widespread. Transmission is the word used for sending (transmitting) large amounts of electricity over long distances. When it reaches its destination, electricity is then distributed to customers. In Western Australia, electricity is transmitted along wires at voltages of up to 330,000 volts (the equivalent of 330 kilovolts or 330 kV).
Why do electrical supply utilities transmit electrical energy at such high voltages? The answer is that some power is lost when electricity is transmitted over distances. The most economical and practical way to minimise this loss of power is to increase the voltage in the power lines. This is done by using “step-up transformers”. Power stations use step-up transformers to increase the voltage, which allows for electricity to be transmitted long distances.
Electricity reaches a customer’s home via the main street power lines, which are connected to service wires, and the meter box. At this stage, the voltage of electricity is either 240 volts or 415 volts. It is brought down from 330,000 volts to 240 volts in several stages. During this process, “step-down transformers” are used to reduce the voltage at various stages along the route as electricity from the power station progresses towards its final destination.
Here is an example of how electricity voltages change during the process of transmission and distribution. In Western Australia, the largest power station is Muja Power Station, which is located some 22km east of Collie. There, electricity is generated at voltages between 11,000 volts and 16,000 volts (11kV-16kV). The electricity voltage is then stepped up to 330,000 volts (330kV) for its long-distance transmission to Perth along overhead wires supported on steel towers.
Above - Muja Power Station - Collie Western Australia.
Source: Verve Energy.
 Google Earth - Muja Power Station
Insulators are used at the points where the live electric wires connect with the steel towers or poles. Insulators prevent the electric current from flowing down through the steel metal to the ground. Insulators are the opposite of conductors. They are materials which do not allow electricity to flow easily through them and they are classed as very poor conductors. Good insulators include materials such as rubber, plastic, glass and porcelain.
Large step-down transformers are located in terminal stations and zone substations. These transformers vary in size according to the electrical load. They reduce the electricity voltages, which is necessary for shorter distance transmission (known as subtransmission) throughout the South West Interconnected System. This large region includes the metropolitan area and country regions from Kalbarri in the north to Albany in the south and Kalgoorlie in the east.
At the terminal stations, the transformers reduce the voltage levels for sub-transmission to 132,000 volts (132kV) and 66,000 volts (66kV). Electricity then flows to the smaller sub-stations. The electricity levels are further reduced to voltages of 33kV, 22kV, 11kV or 6kV. Electricity is then distributed via overhead or underground power lines to customers’ homes and businesses.
For more information about transformers, go to:
 http://en.wikipedia.org/wiki/Transformer
 Next Section >> The early years.
^ back to top ^
|
