Influence of Asynchronous Opening on Arc Characteristics in a Double-Break DC Vacuum Circuit Breaker

Abstract

Asynchronous opening in a double-break DC vacuum circuit breaker leads to a gap difference between the two interruption gaps, which in turn results in nonuniform arc energy distribution and distinct plasma transport characteristics. In this article, a 24 kV/10 kA double-break DC vacuum circuit breaker is investigated. A numerical model describing asynchronous opening is established to analyze the plasma temperature, pressure, and velocity fields under different gap difference conditions, and the corresponding distribution characteristics and differences are obtained. The results indicate that the gap difference has a significant influence on arc energy and plasma behavior in the double-break configuration. When the gap difference is small, the plasma distributions in the two gaps exhibit similar characteristics, and the arc energy is distributed in a relatively balanced manner. As the gap difference increases, arc constriction in the smaller-gap unit becomes more pronounced, leading to enhanced local energy accumulation and a reduction in the overall energy dissipation capability of the circuit breaker. When the gap difference reaches a critical value, severe imbalance in arc energy and plasma distribution occurs, postarc dielectric recovery is degraded, and arc reignition is triggered, ultimately resulting in interruption failure of the circuit breaker.