Anode and cathode are root movement during contact opening at high current

This paper presents experimental research into the behavior of short circui t break arcs ignited between opening contacts. The investigation is applied to are chamber geometries commonly used in miniature circuit breakers (MCB ), The movement of the anode and cathode roots are individually plotted fro m optical data, allowing the relative motion to be compared. The effect of a range of MCB configurations on the are root motion has been investigated. The experiment was configured so that the fixed contact was always the cat hode. The results show that the two are roots do not move away from the con tact region simultaneously. Often the cathode root moved off the fixed cont act and away from the contact region before the anode root commutated from the moving contact, The delay in anode root commutation leads to a delayed cathode root movement, These events are explained in terms of are root emis sion processes.