Inrush current prestriking arc behaviors of vacuum interrupters under CuCr50/50 and CuW10/90 contact materials

In the case of back-to-back capacitor banks switching, the inrush current arcs can locally melt the contact surfaces of vacuum interrupters (VIs) during prestrike processes. The contact materials significantly influence the behaviors of the inrush current prestrike arcs. The objective of this paper is to determine the influence of contact materials on inrush current arc behaviors of vacuum interrupters during capacitive switching prestrike processes. The inrush current arc behaviors were observed by a high-speed camera. The contact diameter of the VIs was 48 mm and the insulating envelope was transparent. There was no metal shield inside the VIs. Two different contact materials (CuCr50/50 and CuW10/90) were used in the experiment. It is found that the diffuse prestrike arcs phenomenon is more observed in VIs with CuW10/90 contact material than that with CuCr50/50. The results indicate the impacts of different contact materials on the inrush current prestriking arc behaviors and the erosion pattern.