Comparison of the Characteristics of Upward Leader Emerging From the Ground Wire and Conductor

An understanding of the characteristics of upward leaders from transmission lines is crucial to the analysis of shielding failure. Since data on these characteristics are difficult to capture under natural circumstances, experiments are needed. In this paper, 7-m plane/rod to conductor and plane/rod to ground wire air gap have been used for studying the characteristics of an upward leader from ground wire and conductor, and the differences in the upward leader's initial characteristics between these two were compared. The experimental results show that the streamer and upward leader from the ground wire were incepted much earlier, but the difference in their velocity is small compared with that from the conductor. These conclusions may suggest that the length of the upward leader from the ground wire is longer than that from the conductor, and this condition may lead to the ground wire being struck by lightning more often compared to the conductor when no operational voltage is applied.