Study on the variation of the arc area in vacuum DC interruption

The variation of the arc area in DC interruption was investigated. By the use of the vacuum interrupter with glass shielded, DC interruptions were carried out to obverse the arc appearance in the situation of axial magnetic. Meanwhile, using the CMOS high speed camera, arc images were obtained under the conditions of different commutation frequency, arcing time and pre-charged capacitor voltage. Subsequently, the arc area was obtained through the image processing technology. According to the obtained arc area, the factors influencing on the arc area were investigated, including the commutation frequency, arcing time and pre-charged voltage. The results indicated that the duration time of the commutation stage became shorter and the arc area decreased with the increase of commutation frequency. The rise rate of arc area in initial stage and the drop rate of arc area in commutation stage present the same trend under different arcing time. Considering the experimental results in this paper, arcing time of 2 ms is better for DC interruption. High pre-charged capacitor voltage leads to the increase of the current going through load. The capacitor voltage can be charged a little higher than the rated value for the reliable interruption of DC current.