Particle induced post arc breakdown in vacuum circuit breakers

Charging of macro-particles is shown to occur due to the positive ion flux, in the growing plasma sheath, during the post arc current phase. A theoretical investigation of the influence of these strongly charged macro-particles, on the breakdown of vacuum circuit breakers, is presented. The trajectories of these positively charged particles during the recovery voltage phase is studied. Field emission from the cathode due to these particles is studied. Finally, the trajectories of emitted electrons are studied and breakdown probabilities discussed. The model proposed, gives new insight into the statistical nature of post arc breakdown in vacuum circuit breakers and especially, late breakdowns.