A practical approach for computation of grid current

When a ground fault occurs at a substation, the part of the fault current t hat flows between the grounding system and the surrounding earth is known a s grid current. This current determines the magnitude of the dangerous volt ages within and around the station. It may vary from a few percent to almos t 100% of the earth fault current. It is necessary to make an accurate esti mate of grid current for an economical and safe design of ground electrode. The available analytical methods for determining the grid current require complete system data, which is voluminous and often unavailable. In this pa per a simple and accurate analytical method for determining the grid curren t is presented. The method requires limited data. A computer program based on the proposed method has been developed and tested.