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Who is called Electrical Mains?

The main function of the electric main in the electrical supply system is to transmit the electrical power from the power station to the consumer, a network is established to transmit the electrical power generated from the power station to the consumer. For this the network is mainly divided into two parts.

It refers to the portion of power distribution that moves bulk electricity from production sites to substations over long distances close to areas of power demand. Consumers may recognize transmission lines as large, tall poles/towers that carry multiple wires over long distances. Explain the way from power generation to electricity to the customer

Generation of electricity

Turbine-Generator Set: The output voltage of a power plant generator is typically 23,000 volts and several thousand amperes depending on the megawatt rating. So if a generator is rated at 600MW (MW) and has a power factor of 0.9, you are talking about 15,000 amps. That type of current requires a massive tubular conductor called an isophase bus.

It is basically a 2 ft diameter hollow aluminum tube conductor housed within a larger tube. Such high currents generate huge magnetic fields around the conductor, but the outer tube creates its own magnetic field from the induced currents which cancel the magnetic field of the main conductor. Some iso phase buses are equipped with a blower to cool the conductors. The iso phase bus connects the generator to the primary part of the generator’s step-up transformer.


transmission lines: The generator’s step-up transformer steps up the voltage from the generator from 23,000Volts to 345,000Volts or some other transmission voltage (eg 115KV, 138kV, 230kV, 500kV, 765kV). So that’s a multiplication of 15 times (345,000kV/23,000kV). According to Ohm’s law, for a given amount of power, if the voltage is increased, the current must decrease by the same proportion. So now the transmission current is 15000/15 = 1000Amps. With that low current, you can use thinner aluminum conductors.

This high voltage is used to transmit electricity over long distances. High voltage transmission lines must be carried by very tall towers to avoid arcing to the ground and reduce capacitive losses. The three phases have to be further separated for similar reasons. These types of voltages are also unusable so they must be reduced to a usable level which brings us to the next step.


ILectric Substation: Transmission lines lead to the substations where the switching takes place and more importantly step-down transformers reduce the voltage to the customer’s need. Industrial customers typically get voltage ratings from 2300V to 69kV. Commercial customers may get 460V to 2300V, while a pole-mounted transformer primary is typically 13.8kV (USA) before it is reduced to 120/240 volts with a typical split phase for home use.

Also read: 5′ Concept

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