Particle Generation, Their Behavior and Effect on Post-Arc Breakdowns After Capacitive-Current Vacuum Arc Interruption

Abstract

Post-arc breakdowns of vacuum circuit breakers during capacitive operation can be possibly caused by particles. In this work, we experimentally observe the generation and dynamics of particles in capacitive interruptions and their resultant effects on post-arc breakdowns. We further constructed a synthetic test circuit for the capacitive current switching and adopted the laser-shadow technique to observe the dynamics behaviors of particles, formed by different electrode materials and inrush currents. CuCr10 electrodes tend to generate particles with high probability and quantity, owing to their weak refractoriness and lower mechanical strength. Furthermore, we find that the higher inrush current facilitates the formation of particles. Additionally, under the influence of recovery voltages and variable charges, particles show complex and diverse dynamic behavior, such as bouncing, oscillating, levitating, lifting, and rotating. Essentially, all particles relevant to breakdowns moved at a low speed (below 0.5 m/s), besides, almost all non-sustained disruptive discharges and restrikes are concerned with the particles closed to electrodes under near-peak recovery voltage. Therefore, we think neither energy accumulation nor high-speed bombardment of particles can explain post-arc breakdowns, conversely, the joint effect of particle-induced field enhancement and resulting field electron emission is responsible for breakdowns.