Mechanism of dynamic voltage distribution in series-connected vacuum interrupters

Abstract

This paper proposes the equivalent circuit of dynamic VD (PVD) in multi-break vacuum circuit breakers (VCBs). The equivalent circuit is composed of controlled post-arc sources, post arc resistors and equivalent capacitors. The PVD is divided into four processes: the initial transient recovery voltage (TRV) process, the oscillating TRV process, the stable TRV process and the power-frequency voltage process, which can be analyzed by the equivalent circuit. The PVD is investigated in the synthetic circuit with multi-break VCBs. After the current zero, the post arc current and the current of the grading capacitors are measured. The TRV distribution in the post-arc dynamic dielectric recovery is obtained to analyze the PVD in the third and fourth process. The initial and later TRV process is researched by the post arc current and post arc charge in the successful interrupting process. Therefore, the mechanism of the PVD in multi-break VCBs is obtained and described by the equivalent circuit, which is useful to gain even voltage distribution (VD) and improve the breaking capacity of multi-break VCBs.