Role of vacuum interrupter contacts in dielectric recovery phenomena

The behavior of vacuum-circuit-breaker (VCB) contacts related directly to arc extinction in the arc current-zero region dominates the postarc dielectric recovery. The practical dielectric recovery processes were investigated to determine the role of VCB contacts in this process. Experiments show that the process can be divided into two stages. In the earlier stage, the sheath near the contact surface produced by recovery voltage is dominant. Arcing history expressed by the ion energy also plays a role. In the later stage, contact erosion, surface deformation, and background pressure are important factors. For comparison, free-dielectric recovery was measured with the same sample conditions but without recovery voltage. The results of this work clarify the comprehensive pattern of the practical dielectric recovery phenomena of vacuum arcs