Study on the influencing factors of reignition characteristics for 40.5kV vacuum circuit breakers

When 40.5kV vacuum circuit breakers are used to break currents in distribution system, reignition phenomena occur frequently resulting in high overvoltage and even interruption failure. In order to further the understanding of the reason of multiple reignition characteristics and give practical advice to vacuum switchgear manufacturers and users, research work has been completed based on plenty of tests. A synthetic circuit that can apply a DC recovery voltage after current zero for a long period was used to study multiple reignition phenomena in switching. Some key factors including breaking current, clearance between open contacts, electrode structure and contact material, which may affect reignition characteristics, were studied. Under various clearances, the statistical probability of reignition is obtained. As a result, the best scope of clearance between open contacts is found. The performance of CuCr50/50 and CuCr75/25 material was compared. Two kinds of electrode structures, namely 1/2 coil structure and cup-shaped axial magnetic structure, were tested. After high-current interruption, conditioning effect is reached and the probability of reignition decreases.