Effect of grounding resistance connected to surge arresters in power distribution lines on lightning surge behavior observed in customer's equipment

In Japan, electric power companies have been spending a large amount of money on the construction cost and maintenance cost of low grounding resistances connected to surge arresters (Arrs) that is basically maintained below 30O. In a recent study, it has been clarified that the rate of protection against direct lightning hits on distribution lines with an overhead ground wire (GW) hardly decreases, even if the grounding resistance of Arrs is high. However the installation of Arrs on a pole where a pole transformer (Tr) is mounted has not been considered, and in the case of a high grounding resistance, the lightning surge behavior observed in customer's equipment has not yet been clarified. To examine the grounding resistance of Arrs, it is necessary to understand such behavior in the case in which the grounding resistance of Arrs is varied. In this paper, we clarified the relationship between the grounding resistance connected to Arrs and lightning surge behavior in customer's equipment. The result shows that the grounding resistance of Arrs installed on a pole with a Tr can be increased to some extent without decreasing the lightning protection level of the customer's equipment by the installation of a GW and the shortening of the interval between concrete poles with Arrs. A reduction in the cost of grounding construction can be expected. © 2014 The Institute of Electrical Engineers of Japan.