Arc Evolution and Extinction Mode of Large-Current Vacuum Arc Based on Forced Current Zero

The Generator circuit breaker (GCB), based on vacuum arc extinguishing technology, is the key electrical equipment in the power system. The short-circuit breaking requirement of GCB was much higher than that of the conventional vacuum circuit breaker, there was a lack of research on the vacuum arc under large-current. Firstly, a large-current vacuum arcing experimental platform based on forced current zero and detachable vacuum chamber (DVC) was built, equipped with the 80 mm diameter cup-shaped axial magnetic contacts, and the peak experimental current was 100 kA. A high-speed camera was used to synchronously record the vacuum arc morphology. For the different arcing times, the evolution process of large-current vacuum arcs was investigated, including multi-point arc initiation, multi-arc column merging, single-arc column movement, and arc extinction. Based on the number and position of arc columns before the current-zero, the arc extinction modes were classified into multi-arc extinction mode (ME), single-arc off-center extinction mode (SO), and single-arc central extinction mode (SC). Further, the effect of arcing time on the arc extinction mode was analyzed, and it was found that as the arcing time increased, the evolution of the vacuum arc would cause the arc extinction mode to undergo the “ME-SO-SC” transformation. The conclusions will promote the research and application of the environmentally friendly large-capacity GCB.