DC Breakdown Characteristic of Air Gap With Water Droplets

Under rain conditions, the sliding water droplets on the insulator’s surface shorten the air insulation distance between the sheds and even cause a flashover. In order to study the mechanism of air gap breakdown with rain droplets, the breakdown process was recorded by a high-speed camera and the influences of rain water droplets (conductivity, volume, and position) were studied. The experimental results show that the impact of the water droplets on the direct current (dc) breakdown voltage is related to the air gap length. The shorter the air gap, the greater the drop of the flashover voltage. Although water conductivity does not affect the breakdown voltages, the arc development path is related to it. This research has significance for revealing the rain flashover mechanism of insulators.