Experimental Investigation of the Breaking Arc Behavior and Interruption Mechanisms for AC Contactors

For alternating current (ac) contactors, the direct consequences of breaking arcs are material erosion and its associated electrical contact failure. In this article, the ac arc of a commercial contactor is simulated experimentally and the relevant arc characteristic parameters are recorded. The effects of contact gap and point-on-wave at break (POW) on arc behavior, including arc voltage, conductance, arc duration, and termination voltage are investigated. In particular, the arc reignition phenomenon at small contact gaps is observed and explained. Finally, two interruption mechanisms of the ac arc (zero-crossing termination and mechanical ruptured termination) are revealed based on the variations in arc termination voltage as a function of POW.