Electrical Breakdown of High-Temperature Gases and Its Implications in Post-Arc Phenomena in Circuit Breakers

The breakdown strength of a hot gas and the kind of breakdown, dielectric or thermal, is believed to depend upon the electrical conductivity of the gas. Two methods have been applied to measure conductivity, one using a low-voltage probe and the other a microwave beam. The results yielded by the two methods gave better than an order of magnitude agreement. It is found that breakdown depends upon electron concentration and, more specifically, that the type of breakdown is also determined by it. These results shed light on post-arc conditions in circuit breakers.