Experimental Investigation of High-Current Vacuum Arc Instability Modes Under Transverse Magnetic Field

The behavior of vacuum arc influences the heat distribution on the contacts and the contact melt and erosion, and thus, it greatly affects the breaking capacity after current zero. In this paper, high-current arc instability modes were investigated in a demountable vacuum chamber with a high-speed charge-coupled device video camera. Three kinds of spiral contacts were used with CuCr50 as the contact material. We observed and summarized three types of arc instability modes: 1) multicolumn arc mode; 2) single stationary jet mode; and 3) single moving jet mode. As the peak current increases, the instability mode will transition from multicolumn arc mode to single stationary jet mode, and then to single moving jet mode. We also found the periodical transition between the plasma jet and the relatively diffuse columnar arc during single moving jet mode. It was shown that the occurrence of arc instability modes, especially the single moving jet mode, is usually accompanied by the increase in mean value and high fluctuations on the arc voltage. Besides, during the instability mode, a large number of droplets and macroparticles will be produced in the gap. These will have a great influence on the interruption capacity of the vacuum interrupter.