Substations

Substations are the places where the level of voltage experiences change with the help of transformers. Apart from transformers the substation will house switches (termed as circuit breakers), meters, relays for security and other control equipment. Broadly talking, a big substation will receive power via incoming lines at some voltage (let say 400 kV) changes level of voltage (let say to 132 kV) by using a transformer and then directs it out wards via outgoing lines. Pictorially like typical power system is shown in figure below in a short of block diagram. At the lowest voltage level of 400 V, usually 3-phase, 4-wire system is accepted for domestic connections. The fourth wire is termed as the neutral wire (N) that is taken out from the general point of the star connected secondary of the 6 kV/400 V distribution transformer.

                                                       Figure: Typical voltage levels in a power system.