In order to transmit electricity, the voltage must be increased. By raising the voltage, the circulating current is reduced and losses from the Joule effect decrease. The voltage is increased at the transformer stations and travels from substation to substation until it reaches the receiving stations in cities.
The invention and refinement of transformers, capable of efficiently raising and lowering the voltage of an alternating current, made it possible for the power stations to be built far from centres of consumption.
At present, the power supply is transported through cables of high and very high voltage from between 220,000 and 440,000 V.
In 1914, Capdella supplied 110,000 V of energy. Today, electricity lines with this level of voltage are no longer installed.
The high-voltage cables are connected by towers. The lines coming out of Capdella run 175 km in a straight line to the towns where the electricity is consumed. Before the electricity is consumed, the voltage drops to 220 V, which is used by domestic appliances and lighting.
The electricity we consume is measured in watts/hour. The amount of energy consumed is invoiced in kilowatts/hour (kWh). A television set switched on for 20 hours consumes one kWh.