Transmission of electric power is the movement of electricity from the point of generation (generation station) to the point of distribution (distribution station). This is done through cables called transmission lines. Transmission of electricity can be done at both low and high frequencies.
Transmission lines are made of copper wire coated with lead or aluminium, and they can be single care or stranded. The lines can be overhead or underground. The overhead lines are drawn through pylons (steel wires) while underground lines are buried. Transmission is done at voltages much higher than those used in our homes to operate electrical equipment and appliances.
TRANSMISSION OF ELECTRIC POWER AT LOW FREQUENCY
Frequency is the number of cycles per second. Its unit is the Hertz(HZ). Afrequency of 50 cycles per second is equal to 50hz, and it is a low frequency. In a country like Nigeria, electricity is is generated and transmitted at a low frequency of 50hz, while in America, it is 60hz. The generating stations may be far removed from the towns and villages and the transmission is done at voltages much higher than those used in our homes to operate electric appliances. In Nigeria, electricity is transmitted in the following common voltage ranges from 11KVA, 33KVA and 132KVA.
TRANSMISSION OF ELECTRIC POWER AT HIGH FRQUENCY
Transmission of electricity at high frequency is done through electromagnetic waves(radio wave). An electromagnetic wave can simply be referred to as electrical energy that travel in space. Electricity does not travel through conductors only. Electromagnetic waves travel at a high speed and frequency of up to 30,000 mega Hertz. The radio, television, GSM set, internet and radio communication equipment are all operated by electromagnetic waves. The electric power consumed in our different homes comes from a generating station. In the same way, the electromagnetic waves that are received in our radio, television, and GSM sets are first generated and then transmitted.
In a radio communication system, the message is given through a microphone connected to a transmitter, which generates the radio wave at a high frequency. An aerial connected to the transmitter through a cable called transmission line, sends out the radio waves into space. A receiver aerial connected to a receiver equipment like radio,TV, GSM set comes across the wave radiated into the space and sends them into the receiver equipment. At the receiver, the desired transmitter signal is selected, amplified and converted to the original message. The information is then extracted out of the radio wave.