Influence of Metal Vapor and Composite Material on the Decaying Conductance of a Low -Voltage Circuit Breaker

Abstract

In a low-voltage circuit-breaker (LVCB), the contact opening leads to the formation of an arc in air, that is moved to an extinction chamber. During its displacement, largely due to external electromagnetic forces, the arc interacts with rails and with the walls made of composite material. The material ablation creates an increase of the local pressure that favors the arc movement. But the presence of metal and carbon vapors that have rather low ionization potentials, may increase the electron number density and, in certain cases, it has been observed an arc restriking near the contacts. In order to study this phenomenon we have been developing a numerical study for calculating the arc movement, the interaction with the walls and all the problems related to the extinction.