Arc characteristics of parallel gap for composite insulator

The arc characteristics are key problems for designing of parallel gaps. Laboratory testing on arc characteristics is significant for accurate arc modeling, and electromagnetic transient problems simulation caused by short circuit fault in parallel gaps. In the paper, the experimental system to study the characteristics of long arc between parallel gap was built, which generated the arc with the initial length of respectively 1m, 2m, 4m, and with current value of 10kA or 40kA. A high-speed camera was used to capture the movement of the arc, and the relationship between the arc macro-morphology and resistance is studied. Arc resistance under different arc lengths and current values was compared. The movement of upper and lower arc root, arc column were observed. The experimental results show that, the lower arc root moves rapidly with a speed of 8cm/ms under 10kA, and the upper root swings randomly. The arc voltage has obvious saturation characteristics, the arc resistance increases with the increasing length and declines with the increasing current. Finally an arc resistance formula based on the experiment results is derived.