Arc extinction using external magnetic field in switching device

Summary form only given, as follows. A mathematical model describing interdependent transient temperature and electromagnetic fields in electrical contacts at the opening stage of contact is discussed. The arc extinction time changes dependent on the magnetic field around the arc column in a DC switching device. The high temperature and pressure arc plasma is formed in the gap between opening contacts. The wear of contact material depends on arcing time at the opening stage and effects on the electrical life of a switching device. So, it is very important in the switching device to shorten arcing time. Also, the arcing time of the DC magnetic contactor is generally longer than that of the AC magnetic contactor because the DC current doesn´t cross the zero crossing point of the current. Therefore many transmission & distribution device makers have made continuous efforts for a smaller, lighter and high reliability contactor with arc extinction units having a high arc extinction performance. A theory on the arc quenching principle of AC and DC magnetic contactors is established in this paper using a mathematical model.