Grid Earthing System

An earthing grid is used as an electrical connection that is located to the earth at zero potential in which when a fault condition occurs then the flow of current dissipates into the ground through the low impedance path.Since low equipment is connected to earth using low resistance wire, balancing is achieved. Metal can be used in electrical installations without looking for its conductivity, proper earthing ensures that metal does not transfer current.Earthing System in a Sub Station comprises of Earth Mat or Grid, Earth Electrode, Earthing Conductor and Earth Connectors. Primary requirement of Earthing is to have a low earth resistance. Substation involves many Earthings thro' individual Electrodes, which will have fairly high resistance.The resistance of the earth electrode depends upon the resistivity of the soil in which the electrode is inserted. Therefore, it is crucial to measure the resistivity during the design of any earthing installations. Earth resistance is the resistance of the ground electrode measured to perform a resistance check.