Experimental investigation on arcing evolution and arcing uncertainty in ultra-high-current vacuum arc

To meet the interruption demand of the large-capacity generator circuit breaker (GCB), an experimental platform for ultra-high-current vacuum arcing was established, and arcing experiments with the peak current of 100 kA were carried out. A high-speed camera was used to synchronously record the arc morphology. Firstly, the effects of arcing time on the volt-ampere characteristics and morphology evolution of ultra-high-current vacuum arcs were investigated. As the arcing time increased, the arc voltage and equivalent resistance increased as a whole, the volt-ampere characteristic curve changed from a “┐” shape to a “7” shape, and a pronounced positive volt-ampere characteristic appeared in the later arcing stage. At different arcing times, the vacuum arc generally followed the basic evolution pattern of “multi-point arc initiation→multiple arcs→single arc→diffusion→extinction”. Meanwhile, the arc evolution exhibited clear inheritance. With increasing arcing time, more complex arc behaviors further appeared, including competitive merging among multiple arc columns, local splashing, off-center motion, and expansion-contraction. In addition, it was found that, under identical conditions, the arcing evolution of ultra-high-current vacuum arcs was not uniquely determined, but exhibited significant uncertainty. The arcing evolution process was divided from the perspective of uncertainty, and the correspondence among arc morphology, evolution stage, and arcing uncertainty was revealed. The possibility that arcing uncertainty may be transmitted to post-arc dielectric recovery was also discussed. These results deepen the understanding of the physical characteristics and behavioral law of the high-current vacuum arc, and provide an experimental basis for the design and development of the large-capacity vacuum GCB.