Arcing uncertainty in high-current vacuum arcs and its influence on post-arc transient dielectric recovery

Abstract Large-capacity vacuum generator circuit breakers (GCBs) are essential for the safe operation of power systems, yet extremely high short-circuit currents and steep transient recovery voltage rise rates pose challenges to current interruption. In this work, an experimental platform for high-current vacuum arcing and post-arc transient dielectric recovery was established. High-current tests with the peak current of 100 kA were conducted using 80 mm diameter axial magnetic field contacts, and the evolution of arc morphology was recorded by a high-speed camera. Based on arc motion and volt-ampere characteristics, the arcing process was divided into five evolutionary stages. Repetitive tests under identical conditions revealed, for the first time, the existence of arcing uncertainty. The influence of arc morphology evolution on arcing uncertainty at different stages was clarified, showing that the vacuum arc possesses an inherent self-regulating capability that gradually transforms highly uncertain states into less uncertain ones. In addition, an arcing memory effect was identified. The influences of arcing energy and arc morphology on post-arc transient dielectric recovery were elucidated, demonstrating that arcing uncertainty is the key factor responsible for its dispersion. Finally, design considerations for the large-capacity GCB were proposed from the perspectives of arc behavior control and safe post-arc interruption, providing a basis for the engineering application.