In the power station, a transformer increases the electrical voltage to 130,000 volts before it is sent out into the power grid. To use the electricity in the substation, a transformer in the substation must then lower the voltage to 6,000 volts. For comparison, typical household outlets operate at 230 volts.

By using a transformer, large amounts of electricity can be transmitted without the need for excessively thick wires.

To understand how a transformer works, you can imagine electrical power as a water hose. For a narrow hose to deliver the same amount of water as a thick hose, the water must flow faster through the narrow hose.

A transformer does the same thing with electric current. By reducing the electrical current (the thickness of the hose) while simultaneously increasing the voltage (the speed of the water), it maintains the same power output. Current is measured in amperes (A) and voltage in volts (V).

This model represents a transformer wagon, manufactured by ASEA in 1934.