Breakdown characteristics of combined air gaps under lightning impulse

Abstract

With the increase of both voltage level and the transmission capacity, more attention has been paid to the external insulation of transmission lines. As the main external insulation medium of transmission line, the air gap’s dielectric strength will change when there are floating conductors. In this paper, we established an experiment platform to study the effects of floating conductors, simulated by floating rod electrode, on breakdown voltage, breakdown time, electric field distribution and discharge physical process of long air gaps under lightning impulse. The results showed that the intervention of floating electrode reduced the breakdown voltage and breakdown time of long air gaps, and the position with the longest breakdown time was the same as the position with the lowest breakdown voltage. In addition, the intervention of floating electrode improved the spatial electric field and complexity of discharge physical process.