The Effect of Cloud-to-Cloud Lightning on Medium Voltage Lines

The effect of Cloud-to-Cloud (CC) lightning on Medium Voltage (MV) lines has previously been assumed to be negligible due to the distance between the line and the CC lightning channel [1]. During a study [2] to distinguish between nearby Cloud-to-Ground (CG) lightning and direct lightning strikes to a 714 km (including branches) 22 kV line, lightning-related line faults were measured also where only CC lightning was present. These line faults were investigated and the network and CC lightning were modelled. It was found that the faults were initiated by CC lightning but that the flashover could be attributed to insufficient wet creepage distance and not due to insufficient Basic Insulation Level (BIL).