Research of Micro-particle Impact Phenomena on Contact Surface in Vacuum Interrupters

Micro-particle impact phenomena were regarded as an important potential agency for initiating vacuum breakdown in vacuum interrupters (VIs). The objective of this paper is to study the micro-particle impact phenomena in VIs based on the hydro-dynamical theories of projectile impact, by introducing Smoothed Particle Hydrodynamics (SPH) method into the research of vacuum breakdown to simulate the microparticle impact phenomena. In this paper, the micro-particle and the contact were assumed to be made of two different materials, copper and stainless-steel, used to distinguish between projectile and target. The diameter of micro-particle was assumed to be 0.1 mu m. The contact gap was 2 mm. The voltages applied between the contacts were 10 to 60 kV AC rms. First, the electric field distributions at voltage peak under different applied voltages were analyzed. The maximum electric field strength under different applied voltages was obtained. Then micro-particle charges and the impact velocities under different applied voltages were calculated. Finally, the dynamic impact processes were simulated by SPH. The characteristics of the craters and the clouds produced by the impact process were investigated. The results could provide some useful information to understand the micro-particle breakdown in vacuum.