Why is power transmitted at high voltage?
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Transmitting Electricity at High Voltages
From coast to coast, electricity travels via high voltage transmission lines in order to supply power to our homes. In some parts of the grid in the United States, electricity is transmitted at up to 500,000 volts. The need for a high transmission voltage occurs when a large amount of power has to be transmitted over a long distance.
The primary reason that power is transmitted at high voltages is to increase efficiency. As electricity is transmitted over long distances, there are inherent energy losses along the way. High voltage transmission minimizes the amount of power lost as electricity flows from one location to the next. How? The higher the voltage, the lower the current. The lower the current, the lower the resistance losses in the conductors. And when resistance losses are low, energy losses are low also. Electrical engineers consider factors such as the power being transmitted and the distance required for transmission when determining the optimal transmission voltage.
There is also an economic benefit associated with high voltage transmission. The lower current that accompanies high voltage transmission reduces resistance in the conductors as electricity flows along the cables. This means that thin, light-weight wires can be used in long-distance transmission. As a result, transmission towers do not need to be engineered to support the weight of heavier wires that would be associated with a high current. These considerations make high voltage transmission over long distances an economical solution.