Development of low resistivity material for grounding resistance reduction

Power system is generally protected from lightning strokes by surge arresters which are provided with a low earth resistance connection to enable the large currents encountered to be effectively discharged to the general mass of earth which offers some resistance to the flow of current. This earth resistance depends on electrode arrangements and the surrounding soil resistivity. In Saudi Arabia, the soil resistivity varies in a large range because the geodetic terrain varies from sea shore to the arid desert and dry mountains. Therefore development of a suitable low resistivity material that can be used in the areas where the ground resistance is high in order to get an acceptable low value of grounding resistance is very important. Combinations of different materials that can be used for ground resistance reduction were studied by laboratory testing. The results are reported in this paper and show that considerable reduction in the grounding resistance can be achieved by use of such materials which in turn can lead to improve grounding performance.