How a Substation Works

Substations have many functions for controlling power flows. For example, they play a key role in dividing long lines into smaller sections. This helps to minimize any disruption to the continuity of service when a section is not functional, during a fault or maintenance period.

The various components found in a substation include: instruments for measuring current and voltage (voltage transformer,
current transformer and power transformer); protective equipment such as circuit breakers, for interrupting a line’s current, or surge arresters, which protect transformers from a voltage spike caused by lightning; control devices, such as disconnect switches and busbars, which are used to switch energy from one line to another almost instantaneously (when sections are out-of-service, for example). Other instruments, such as reactors, capacitors and compensators, are also used to control the voltage in substations.

Most of the substations are automated and remotely controlled; only the most important ones have technical personnel permanently on-site. Maintenance of the other substations is performed by mobile teams.