抄録
Direct lightning strokes are considered to be a main cause of the damage to surge arresters on power distribution lines up to the present. Recently lightning performance of distribution lines has been observed using still cameras and lightning-caused distribution outages on hill-top areas on the coast of the Sea of Japan has been investigated. These research has shown a possibility that lightning backflow current flowing from customer's facility into distribution lines cause the damage to surge arresters on the distribution lines.
We have investigated the lightning backflow current flowing from customer's facility into distribution lines from the point of causing damage to surge arresters. The main results are as follows:
(1) The ratio of electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current.
(2) In the case that grounding resistance of customer's facility is not low, the failure rates of a surge arrester caused by the backflow current due to winter lightning is about more than 90% of that caused by direct lightning strokes.
