Melting phenomena of electric contacts during current interruption

The physical phenomena related to the melting of electric contacts are classified and the relations to electric characteristics are examined. The solid phase and/or the liquid phase exist at melting temperature. Joule heats from the electric circuit accumulate the latent heat till the melting of the contacts. We studied how the phase changes are ruled by electric circuit. The melting phenomena at the contact current interruption were observed electrically and optically.