An electrical substation is the point in the electrical Transmission-Distribution system, where the transformation of voltage form high level to low level or the vice versa happens. The voltage is either stepped up or stepped down at a substation and this is done with the help of large power transformers within the substation.
A Transmission substation transforms the voltage to a level suitable for transporting the electric power over long distances. This is to minimize the capital and operating costs of the system. Once it is transported close to where it is needed, a distribution substation transforms the voltage level suitable for distribution system. The lower distribution voltage is carried form the substation on feeder circuits that eventually make their way to the smaller pole mounted or pad mounted transformers that we see in our neighborhood. These transformers further step down the distribution voltage to the level suitable for the consumer (normally 240volts).A substation itself is not an entity but it is a part of the system. The substation does not generate electricity but it simply converts the power transmitted through existing transmission lines to lower distribution voltages. Electricity is made at a high voltage at generating stations and it is safely changed to lower voltage level.
