Air Arc Squeezed into Insulating Slits - AC/DC Interruption

Abstract

The paper deals with a principle of AC/DC interruption for low voltage air circuit breakers. When fault occurs, by squeezing the arc into constricted insulating slits, the arc resistance would be elevated, resulting in an arc voltage that is higher than system voltage. Hence, the fault current would decrease till the arc plasma cannot be maintained. The AC and DC interruption performance of a test switch based on this method were experimentally studied and analyzed. The breaking waveforms of AC/DC interruption using proposed method were analyzed and presented. The influence of insulating slit dimensions on DC interruption characteristics is experimentally studied. The research shows that a narrower insulating slit would benefit the DC interruption process, resulting in higher arc voltage and shorter interruption time.