Arc-contact-insulating wall interactions in low voltage circuit-breakers

This experimental study deals with the interaction between an electrical arc, the contacts and the insulating side walls in low voltage circuit breakers. The influence of this on the breaking capacity, dielectric strength and device overheating after breaking are shown. In a confined volume, the arc-wall interaction defined the gaseous atmosphere in which the arc develops and depends on the nature of the insulating wall material. The gaseous atmosphere therefore fixes, in part, the arc behavior (arc voltage and arc movement) and the physical-chemical properties of the breaking medium surrounding the metallic surfaces (reducing or oxidizing). The arc-electrode interaction influences the capacity of the arc to transfer from the contacts to the arc quenching region and introduces surface pollution, through contact erosion (droplets, metallic vapors and other components). These combined effects can have a negative influence on general circuit breaker behavior.