Grounding Pit Optimization Using Low Resistivity Materials for Applications in High Resistivity Soils

Abstract

Grounding arrangement is very important to maintain safe and reliable operation of a power system and to ensure safety of the power apparatus and operating personnel. In Saudi Arabia, the weather is dry and the soil resistivity varies significantly from area to area because the geodetic terrain varies from sea shore to the arid desert and dry mountains. In most of the inland 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. This paper presents different configurations of grounding pits commonly used with LRM applications. Different parameters that affect the grounding resistance are studied in detail and an optimized pit design is suggested that can effectively reduce the grounding resistance to an acceptable value. 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.