Novel approach of estimating grounding pit optimum dimensions in high resistivity soils

Abstract

Good grounding arrangement is very important for safe and reliable operation of a power system and to ensure safety of the power apparatus as well as the operating personnel. In most of the inland arid desert areas, the soil resistivity is significantly high and it is difficult to get low earth resistance with conventional methods. Therefore, an economical and efficient grounding system design of the earthing pit is necessary which can be achieved by using a low resistivity material (LRM). When such material is used, it is important to optimize the pit design. The grounding resistance for different configurations were calculated and based on the results, an optimized pit configuration is discussed. The intent of this paper is to present a simple general computational technique for finding the optimum economical size of grounding pit when filled with LRM. It was found that the use of too high volume of LRM does not reduce the earthing resistance in a corresponding manner. The suggested method can be readily used by engineers to obtain a good earthing pit configuration for efficient grounding of the power system components in high resistivity soils.