Influence of grading capacitor of multiple‐break circuit breaker on the extinction of secondary arc – a new method for reducing dead time

Abstract

To guarantee the uniform distribution of transient recovery voltage for double-break circuit breaker, grading capacitors are often installed in parallel with each interrupter unit. In this study, the influence of the capacitors on the secondary arc is systematically investigated. First, the equivalent circuit for ultra high voltage transmission line is developed. Taking the capacitor into account, the formulas for the arc current and the recovery voltage, not only the steady state but also the transient, are derived. Meanwhile, the dynamic models for primary arc and secondary arc models have been established in the environment of EMTP. Then, a series of simulations have been performed. The impact of the capacitor on the key quantities of secondary arc, such as the rate of rise of recovery voltage, the arcing time, and the maximum instantaneous current, is comparatively analysed. Furthermore, the capacitor can be extended to suppress the secondary arc, and a novel method is proposed in this study. The operating principle of this method is presented, and its effectiveness is validated through electromagnetic transient simulations. For practical implementation, the technical requirement is finally discussed. The proposed method is simple in structure, and it provides an alternative to the neutral reactor.