Field Enhancement and Vacuum Breakdown Caused by Micro-Particles Induction in High Voltage

The objective of this paper is to investigate the phenomena of field enhancement and micro-particles (MPs) induced breakdown under high voltage. The withstand voltage of vacuum interrupters (VIs) is improved through power frequency conditioning, and the micro-topography of the electrode under saturated conditions is established using a fractal model to obtain the maximum micro electric field intensity. Initially, the instantaneous collision velocities of metal MPs are calculated, considering the material strength equation, state equation, and thermal evaporation process during collisions. The arbitrary Lagrangian-Eulerian (ALE) method is introduced to simulate the high-speed impact of MPs on the electrode, revealing different behaviors when MPs of different radii collide with the metal electrode at various speeds. The results reveal that the conditioned electrode surface exhibits trace of craters and protrusions. Due to the influence of the micro-protrusion, the nearby electric field is greatly distorted. The maximum field enhancement coefficient β of the plate electrode surface is 27.7, while that of the sphere electrode surface is 51.2. Furthermore, calculations demonstrate that the impact of MPs on the electrode surface will generate metal vapor and form an impact crater. MPs with a radius of 1 μm will almost completely evaporate, while MPs with a radius of 10 μm will partially evaporate.