Experimental and Simulation Research on Delay-Time Breaking Property of DC Vacuum Circuit Breaker (VCB) with Multi-breaks

The delay-time breaking property of DC vacuum circuit breaker (VCB) with multi-breaks, based on the experimental platform and the simulation model using combination of line parameter with continuous transition model were analyzed, and the maximum delay-time has been obtained by the contrastive analysis on dielectric strength recovery and the rise rate of recovery voltage. By comparison analysis of the experimental results and simulation, the difference in TRV were obtained. Under different delay-time conditions, short circuit current, and transient recovery voltage (TRV), the maximum delay-time of the DC VCB with multi-breaks was obtained. And the experimental results shown that, when one of the breaks in the multi-breaks cases had a time delay caused by dispersion, and the TVR on the breaks was correspondingly different, which led to the unbalanced distribution of TRV between the breaks. Thus the first triggered break was under higher voltage. To DC VCB with double-breaks, when the delayed time was shorter than 0.5ms, the double-breaks still had the capability of the breaking short circuit current. However, when the delayed time reached 0.5ms, it failed to break. To DC VCB with three-breaks, when a breaker delay occurs interrupting, circuit breaker fault-tolerant performance is best; when the two breakers are delayed, fault tolerance performance degrades; when two breakers delay occur synchronously, maximum delay-time is the shortest. Longer delay time affect the short circuit breaking capability. And the three-breaks had a greater fault tolerance compared with a double-break cases.