The Interaction Between an Arc in the Contact Gap and the Insulation Barrier

The transverse component of the electromagnetic force created in an intercontact gap due to arcing presses the arc to the insulation surrounding the gap which can cause serious damage to the insulation. The depth of the transformed insulation layer under the main arc track is considered as a measure of the degree of thermal damage. The form and dimensions of this layer are investigated experimentally and estimated analytically. The role of radiative and convective heat exchange between the arc column and the insulation surface in the creation of the track edges is discussed. The depth of the damaged layer is experimentally found to be slightly dependent on the arc current and pressing magnetic field .