Electrical substations are the interface between parts of the distribution grid and transmission systems. These fenced off areas (see Figures 1 and 2) step down the voltage in the transmission lines to one that is suitable for the distribution grid. They are also equipped with circuit breakers to protect the distribution system, and can be used to control the flow of current in various directions. They also smooth and filter voltage fluctuations caused by, for example, an increased load.
Transformers lower the very high transmission voltages into a voltage less than 10 000 volts, which is suitable for distribution systems. Substations are also often equipped with a bus that splits off the current in multiple directions, as well as circuit breakers and switches which will allow the isolation and direct control of certain parts of the transmission and distribution systems. Many substations also include capacitors to smooth the voltage output.
Substations can be categorized by their various functions and roles.
For further information please see the related pages below: