How Transmission Losses Occur

An electric circuit transmits energy when an electric voltage forces electrons to move. The transfer of the fixed charge on each electron, combined with the impetus behind it (the voltage), represents a given amount of energy. The higher the driving voltage, the more electrons and therefore the more energy is transferred in a given time.

The rate of transfer of charge is called current. As the electrons move through the conductors, they bounce off atoms, losing some of the energy given to them by the voltage. The tendency for this to happen depends upon the conductor and is known as resistance.

The amount of power transferred in Watts is the voltage multiplied by the current. To move a given amount of energy through a conductor requires a low voltage and a high current or a high voltage and a low current.

For a given conductor, the amount of power lost in the transmission of a current is the square of the current x the resistance, or Loss = I2R

The resistance of an actual conductor is proportional to the resistivity of the material and its cross sectional area. Resistance R = Resistivity/Area

To minimise resistance, use low resistance materials and use large cross sectional areas. So if you want to minimise losses in a long conductor, the best way is to minimise the current and minimise the resistance. This means:

• Keep voltages high and currents low
• Use conductor materials that have a high electrical conductivity
• Use conductors that have a large area.