Before electricity arrives at a business or home, it must travel through a distribution substation. Distribution substations, located near where people use electricity, monitor and adjust circuits within the system.
Substations are fenced-in yards containing switches, transformers and other electrical equipment. The main purpose of distribution substations is to lower transmission voltage to feed the distribution system.
Relays are mechanical switches that will cause a substation breaker to shut off power if it senses a higher-than-normal current. Within the substation, rigid tubular or rectangular bars, called busbars, or buses, feed power to two or more circuits. Circuit breakers automatically disconnect power to a circuit in the event of a failure or interruption in an electric line (see diagram 4).
From the substation, electricity travels on distribution lines.