Factors related to speed and voltage capability of a new high-speed circuit breaker

A new concept for a current-limiting fast circuit breaker was investigated to determine design factors that either significantly limited or enhanced performance capability. Positive factors included location of the arcing contacts adjacent to the corners of a square-shaped magnetic core and application of hydrocarbon additives to the splitter plate structure to suppress arc retrogression. Case venting and use of silver alloy contact pads, as opposed to more refractory metals, were found to be deleterious. Clearing times as low as 0.6 ms were obtained in test circuits with an L/R time constant of 0.9 ms.