Investigation Result of Lightning Surge Current into Earth of Equipment on Power Distribution Line Influenced by Ground Wire

Abstract

Observation of lightning current flowing into earth of various power distribution equipment has been performed by using magnetic pieces in summer of 1996-1997. It has been made on two types (with and without a ground wire) of power distribution lines in Gunma Pref. and Tochigi Pref. of Japan. The authors succeeded in obtaining 1048 surge currents in two years. Using these data, we investigated the relation of the number of installed equipment and the number of surges, frequency distributions of surge currents, and the effect of a ground wire. In addition, we compared the calculated rate of damage on distribution lines with the observed rate. As a result, we have confirmed the effectiveness of the lightning protection method of installing surge protective devices. And we have compared our observed results with another observation results of lightning by LPATS. Out of these data, we have investigated coincidence of observed results and the property of surge currents diverted by surge arresters.