Arcing Characteristics of Secondary Arc of UHV Transmission Lines

In order to investigate the arcing time and motion characteristics of secondary arc, we built a low-voltage simulative platform for testing secondary arc of ultra-high-voltage transmission line. The platform consisted of a secondary arc low-voltage simulative test circuit, a high-speed optical imaging system based on charge coupled device unit image sensor, a secondary arc voltage measurement system based on capacitive divider, and a secondary arc current measurement system based on the Hall effect. Using the platform, we obtained the typical moving trajectories and the corresponding voltage and current waveforms of secondary arcs under the conditions of uncompensated, under-compensated and over-compensated. The results show that the motion characteristics of arc root are different between anode and cathode, but both types have the polarity effect; the motion characteristics have great influences on arc voltage and current. The jump of anode arc root and the short circuit of arc column will result in secondary arc voltage drop; the appearance of cathode arc root can result in the increase of secondary arc current. There are two different types of extinction modes of secondary arcs. One is that the secondary arc burning is stably extinguished naturally when the current crosses zero. The other is that the secondary arc is extinguished briefly, followed by a breakdown after a few milliseconds which leads to arc restrikes, and then a quick extinction. It is concluded that accelerating the plasma deionization of secondary arc channel contributes to rapidly extinguish arcs.