Arc root mobility during contact opening at high current

This paper presents a test system, designed for the investigation of short circuit arcs related to miniature circuit breakers operating in a 240 V, ac supply. An optical fiber imaging system is used to identify arc root motion, with short circuit current up to 6 kA. Two methods are used to measure contact motion, a noncontact linear position sensor, and the optical fiber array. The optical fiber array uses software image processing to identify the position of the arc roots in the arc chamber. The identification of the arc roots allows for a study of the arc immobility at the initial stages of the event. Results are presented on variation of peak current level and arc runner materials on arc root motion for one geometry. The cathode root motion is shown to dominate the event.