Substation Earthing Design

Abstract

Successful operation of entire power system depends to a considerable extent on efficient and satisfactory performance of substations. Hence substations in general can be considered as heart of overall power system. In any substation, a well-designed grounding plays an important role. Since absence of safe and effective grounding system can result in mal-operation or non-operation of control and protective devices, grounding system design deserves considerable attention for all the substations. There are two primary functions of a safe earthing system. Firstly, ensure that a person who is in the vicinity of earthed facilities during a fault is not exposed to the possibility of a fatal electrical shock. Secondly, provide a low impedance path to earth for currents occurring under normal and fault conditions.The earthing conductors, composing the grid and connections to all equipment and structures, must possess sufficient thermal capacity to pass the highest fault current for the required time.