Experimental Investigation to Calculate the Lightning Outage Rate of a Distribution System

A method was devised for estimating the lightning outage rate in distribution lines based on a field study. The observation has pointed out that direct lightning flashes to distribution systems were the main cause of line outages; however, a greater number of arresters reduced the number of distribution line faults due to direct lightning strokes. The observation also suggested that the number of direct lightning strike flashovers changes by two factors: 1) the installation rate of surge arresters and 2) the density of the lines. It is noted that this assumption can be applied to the distribution system that has a greater number of transformer-containing arresters. Based on these factors, a computer program was proposed to estimate the lightning outage rate due to lightning strokes, and the calculated results showed good agreement with the observed values in the actual lines. These results suggest that this method can contribute to the evaluation of lightning protection devices, and can lead to effective lightning protection practices.