Impact Phenomena of Metallic Microparticles under Breakdown Voltages in Vacuum Interrupters

Abstract

This paper studies the impact phenomena of the metallic microparticles with the vacuum gap in the range of 10–50 mm under different breakdown voltages in vacuum interrupters. The results show that for the vacuum gap 10–40 mm, the average impact velocities of the microparticles increase linearly with the increase of the vacuum gap, and the impact could damage the cathode surface, which would cause irregularities and give high local field enhancement, finally it may lead to vacuum breakdown. For the vacuum gap 40–50 mm, the average impact velocities of the microparticles are thought to enter the saturation region and remain nearly constant. The impact could cause more metal vapor, which may lead to developing gradually into the vacuum breakdown. Furthermore, the materials with the higher yield stress will cause more obvious fractures and broken phenomena on the edge of the craters, which would have an influence on the vacuum breakdown.