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The discovery of electricity How electricity is taken to the 1 The discovery of electricity fact sheets reviewed and updated with the assistance of STAV Publishing home Electricity cannot be stored easily and so the generators at brown coal fired power stations work 24 hours a day to produce electricity. From the power station, a complicated <network> of overhead lines and underground cables brings the power to your home. print friendly Conductors and insulators A wire is a convenient means of conducting electricity because electricity flows easily through some metals. It will not readily flow through substances, such as rubber, porcelain, glass, plastics or dry air. To confine electricity to a wire it is necessary that the wire be surrounded by a substance such as rubber, porcelain, or air. Materials through which electricity flows easily are called conductors and non-conductors are materials through which it will not flow. Insulators are non-conductors which prevent electricity escaping from the conductors. CONDUCTORS INSULATORS PLASTIC INSULATOR WIRE CONDUCTOR 2 print friendly 3 Voltage and current Before the electricity supply system can be explained in further detail, it is necessary to understand the meaning of the terms “voltage” and “current’. Voltage is the term used for electrical pressure and may be compared with pressure under which water flows through a pipe. Current is the term used for the rate of flow of electricity in a conductor and corresponds to the rate of flow of water in a pipe. The amount of electrical power which can be transmitted (carried) depends upon the voltage (pressure) and the current (rate of flow). By using high pressure electricity, we can transmit a large amount of electrical power through comparatively thin wires in the same way as a lot of water power can be passed at high pressure through small pipes. Pressure is always in a water pipe. The current of water flows only when the tap is turned on. Power stations throughout the State are interconnected by a 6,359 kilometre network of high voltage transmission lines. If these lines were operated at the normal household pressure (230 volts), enormous wires many metres in diameter would be required in place of the conductors now used. Long distance transmission of electricity is impossible without a high voltage. PRESSURE IS ALWAYS BETWEEN WIRES CURRENT OF ELECTRICITY FLOWS ONLY WHEN THE CIRCUIT IS COMPLETED BY CLOSING THE SWITCH A SMALL PIPE CARRYING WATER AT HIGH PRESSURE WILL CONVEY AS MUCH WATER AS A LARGE PIPE AT LOW PRESSURE print friendly From power station to your home Electricity is generated in power stations at voltages of between 6kV and 20kV (6,000 volts and 20,000 volts). This sounds high, but the pressure of the electricity is increased even further through transformers at the power stations before it commences its journey along transmission lines. These transformers are able to “step-up” (increase) the voltage to 220,000 volts and even 500,000 volts, which is 917 and 2,083 times respectively greater than the household supply. This high voltage helps electricity travel along the wires better: The extra high voltage transmission system is connected to the main centres in the State. Major switching centres and substations transform the very high voltages down to 66,000 volts which is used for the sub-transmission system around the metropolitan area and some country districts. Zone substations have further step-down transformers which lower the voltage to 22,000 or 11,000. Electricity at this voltage (pressure) can then be transmitted on smaller, lighter power poles. The supply is finally reduced to 230 volts by pole or small ground level transformers, and so to homes, factories and offices. Most houses receive their power supplies from overhead mains (wires) because it is cheaper than underground cables but in some areas people are prepared to pay more for undergrounding. In Victoria developers of new housing estates are required to put new infrastructure underground. This improves the appearance of the houses and neighbourhood. 4 NEMMCO manages the interconnected transmission network from two control centres in different states. Each of Victoria’s transmission and distribution businesses has their own control centres to direct the operation of their networks. Electricity is supplied directly, to more than 2.3 million customers. print friendly How electricity is taken to the home Further investigations How electricity is taken to the home <http://en.wikipedia.org> Voltage: <http://en.wikipedia.org/wiki/Volt> Direct current: <http://en.wikipedia.org/wiki/Direct_current> Alternating current: <http://en.wikipedia.org/wiki/Alternating_current> Conductor: <http://en.wikipedia.org/wiki/Conductor> Insulator: <http://en.wikipedia.org/wiki/Insulator> 5 Conductors and insulators: <http://hyperphysics.phy-astr.gsu.edu/hbase/electric/conins.html> <http://www.regentsprep.org/Regents/physics/phys03/ainsvscon/default.htm> <http://www.glenbrook.k12.il.us/gbssci/phys/Class/estatics/u8l1d.html> <http://www.thetech.org/exhibits/online/topics/13a_flash.html> print friendly How electricity is taken to the Electricity cannot be stored easily and so the generators at brown coal fired power stations work 24 hours a day to produce electricity. From the power station, a complicated <network> of overhead lines and underground cables brings the power to your home. Conductors and insulators A wire is a convenient means of conducting electricity because electricity flows easily through some metals. It will not readily flow through substances, such as rubber, porcelain, glass, plastics or dry air. To confine electricity to a wire it is necessary that the wire be surrounded by a substance such as rubber, porcelain, or air. Materials through which electricity flows easily are called conductors and nonconductors are materials through which it will not flow. Insulators are non-conductors which prevent electricity escaping from the conductors. Voltage and current Before the electricity supply system can be explained in further detail, it is necessary to understand the meaning of the terms “voltage” and “current’. Voltage is the term used for electrical pressure and may be compared with pressure under which water flows through a pipe. Current is the term used for the rate of flow of electricity in a conductor and corresponds to the rate of flow of water in a pipe. The amount of electrical power which can be transmitted (carried) depends upon the voltage (pressure) and the current (rate of flow). By using high pressure electricity, we can transmit a large amount of electrical power through comparatively thin wires in the same way as a lot of water power can be passed at high pressure through small pipes. Power stations throughout the State are interconnected by a 6,359 kilometre network of high voltage transmission lines. If these lines were operated at the normal household pressure (230 volts), enormous wires many metres in diameter would be required in place of the conductors now used. Long distance transmission of electricity is impossible without a high voltage. From power station to your home Electricity is generated in power stations at voltages of between 6kV and 20kV (6,000 volts and 20,000 volts). This sounds high, but the pressure of the electricity is increased even further through transformers at the power stations before it commences its journey along transmission lines. These transformers are able to “step-up” (increase) the voltage to 220,000 volts and even 500,000 volts, which is 917 and 2,083 times respectively greater than the household supply. This high voltage helps electricity travel along the wires better: The extra high voltage transmission system is connected to the main centres in the State. Major switching centres and substations transform the very high voltages down to 66,000 volts which is used for the sub-transmission system around the metropolitan area and some country districts. Zone substations have further step-down transformers which lower the voltage to 22,000 or 11,000. Electricity at this voltage (pressure) can then be transmitted on smaller, lighter power poles. home developers of new housing estates are required to put new infrastructure underground. This improves the appearance of the houses and neighbourhood. NEMMCO manages the interconnected transmission network from two control centres in different states. Each of Victoria’s transmission and distribution businesses has their own control centres to direct the operation of their networks. Electricity is supplied directly, to more than 2.3 million customers. Further investigations How electricity is taken to the home <http://en.wikipedia.org> Voltage: <http://en.wikipedia.org/wiki/Volt> Direct current: <http://en.wikipedia.org/ wiki/Direct_current> Alternating current: <http://en.wikipedia. org/wiki/Alternating_current> Conductor: <http://en.wikipedia.org/wiki/ Conductor> Insulator: <http://en.wikipedia.org/wiki/ Insulator> Conductors and insulators: <http://hyperphysics.phy-astr.gsu.edu/ hbase/electric/conins.html> <http://www.regentsprep.org/Regents/ physics/phys03/ainsvscon/default.htm> <http://www.glenbrook.k12.il.us/gbssci/ phys/Class/estatics/u8l1d.html> <http://www.thetech.org/exhibits/online/ topics/13a_flash.html> The supply is finally reduced to 230 volts by pole or small ground level transformers, and so to homes, factories and offices. Most houses receive their power supplies from overhead mains (wires) because it is cheaper than underground cables but in some areas people are prepared to pay more for undergrounding. In Victoria The discovery of electricity fact sheets reviewed and updated with the assistance of STAV Publishing