Detachment of microparticles from electrode erosion and the subsequent breakdown

Resulted from electrode erosion, microparticles is common and inevitable in gas switches. Once these microparticles acquire field-induced charge and flee into the gap, there micro-discharge, impact damage and field distortion may occur, which eventually cause undesirable electrical breakdown. This paper firstly introduces the detachment criteria of microparticles based on contact pressure, and discusses the microparticles’ detachment criteria under vibration. Results indicate that the larger microparticle could be detached more easily and the detachment criteria is strongly influenced by vibration and working coefficients. Then combined with previous experimental results, how breakdown is induced by the detached microparticles is discussed based on field electron emission. Results indicate that when suffering strong vibration, these charged microparticles could get detached from the electrode surface, act as the field emission source and finally ignite the undesirable electrical breakdown of switches.