Reliability Analysis of DC Vacuum Circuit Breaker Based on Complementary Effect of Mechanism Velocity and Current Drop Rate

The DC vacuum circuit breaker consists of the vacuum interrupter, the mechanism system, and the commutation system. In order to select commutation parameters and design mechanical characteristic, it is necessary to consider the variation of mechanism velocity and pre-zero current drop rate. For the reliability of DC vacuum circuit breaker systems, it is expected that the greater the mechanism velocity and the smaller the pre-zero current drop rate, the higher the dielectric recovery strength and insulation performance in post arc. However, fast mechanism velocity and small pre-zero current drop rate can easily lead to subsystem lose efficacy. For researching the complementary effect of above two aspects in improving the reliability of DC VCB, based on the initial number density of particle computational equation of post arc, the Maxwell Stefan equation, and the electric field Poisson equation, the model for the development of the post arc sheath is established to research the dynamic insulation and dielectric recovery characteristics under the coupling of multiple factors. Moreover, a reliable DC fault breaking criterion is proposed, and the reliability analysis of DC vacuum circuit breaker based on the complementary effect of mechanism velocity and pre-zero current drop rate is performed.