A new realistic transient model for restrike/prestrike phenomena in vacuum circuit breaker

Abstract

Vacuum circuit breakers (VCBs) are increasingly used in power systems. During the operation of a circuit breaker (CB), several incidents such as prestrike, restrike and current chopping might happen which cause erosion in the contacts of the CB and high frequency inrush current. The evaluation of these transients are highly important due to their influence on the switching overvoltage, as well as their dependency to the statistical behavior of the dielectrics. Accordingly, this paper presents a new realistic model for VCBs with respect to the three factors as follows: I-probabilistic breakdown voltage, II-probabilistic operation-velocity and III-nonlinear movement of the contacts. The results based on the proposed model have been compared with other published-experiments and those obtained based on the conventional model in the Helmer circuit. The results are indicated that ignoring the probabilistic behavior of the parameters or linear consideration for breakdown voltage led to the imprecise estimation of transient parameters such as transient recovery voltage (TRV), rate of rise of recovery voltage (RRRV) and the number of breakdowns. The results indicated that using the improved model led to a 60% and 20% change in TRV peak and RRRV, respectively.