A substation possesses high voltage electric system facility. It is used for switching equipment, generators, and lines in and out of a system or circuits. It is also used for changing AC voltages from one level to other, changing direct current to alternating current or alternating current to direct current. Some substations are not that larger, it just possesses associated switches and a transformer. Others are very large with huge number of switches and other equipment and several other transformers.
A substation which is equipped with a step up transformer enhances the voltage through lessening the current, whilst the step down transformer reduces the voltage while enhancing the current for commercial and domestic distribution. The term ‘substation’ has been into existence days before the distribution system develops into a grid.
The first substations were linked to only one power station where the generator was located, and were supplementary of that power station.
Electric Substations usually have control equipment, protection and switching, and one or more transformers. In the large substation, circuit breakers are used for interrupting any overload currents or short circuits that may perhaps happen on the network. Smaller distribution stations might use fuses or recloser circuit breakers for safety or defense of distribution circuits. Substations do not generally have generators, though a power plant may possibly have a substation close by. Other equipment, like voltage regulators and power factor correction capacitors might also be situated at a substation.
High rise buildings might have several indoor substations. Indoor substations are generally found in urban areas for lessening the sound from the transformers, because of the appearance, or for protecting switchgear from extreme pollution or climate conditions. Where a substation possesses a metallic fence, it should be properly grounded for protecting people from high voltages that might occur in a fault in the network.