Step-up transformers produce the extremely high voltages needed in order to efficiently transmit electricity through the National Grid power lines. Step-down transformers reduce the voltage so the electricity can be safely used at the local level.
Transformers are electrical devices specifically designed to alter the voltage of electric AC current. There are two types of transformers at work on the National Grid. Those that increase voltage are called step-up transformers. Those that reduce the voltage are known as step-down transformers.
Higher currents generate more heat. This means that some energy is lost. In order to increase the efficiency of the National Grid, current is transmitted at a low level. In order to accomplish this task, an extremely high voltage is required. While power stations generate electricity at just 25,000 volts, electricity travels through the National Grid between 132,000 and 400,000 volts.
This increase in voltage is accomplished through step-up transformers. This allows the National Grid to effectively transport large amounts of electricity without wasting energy on heat generation. When the electricity is ready to be used at the local level, the voltage has to be reduced. This is accomplished through a step-down transformer. This voltage reduction makes the electricity safe to use in homes.