Efficiency evaluation of lightning fault inspection in 66 kV transmission line

Abstract

Transmission line must be immediately inspected when it was struck by lightning. It is necessary to find and change the damaged part promptly in case the damage is serious. Such case, however, is actually hardly seen due to the fact that the lightning protection system is well designed recently. Therefore, it is important to compare the data of past lightnings and of the transmission line, and make criteria for deciding more precisely in which case the actual inspection should be carried out. The criteria would be as follows: (1) Insulator voltage exceeds critical voltage. (2) Arc current and arc duration exceed characteristic of insulator destruction. (3) Accident phase exceeds 3 line ground fault. (4) Tower foot resistance is up to 10ohm or more. (5) Lightning current is positive characteristic. By using this criteria, the number of lightning fault inspection was reduced by 34%.