The role of the arc flux and joule heating in the erosion of electrical contacts

The mathematical model describing dynamics of heating and the arc erosion in opening electrical contacts is presented. The arc heat flux components entering and leaving electrode surfaces owing to ion bombardment, electron emission, inverse electron flux and radiation from the arc, melting, evaporation and heat conduction are taken into account. The temperature distribution in the contact zone is found in the form of the sum of two terms. The first term is produced by the total arc heat flux on the contact surface and associated with the boundary conditions of the problem, while the second one occurs due to Joule heating in the constriction zone and appears as a volume heat source in the differential heat equation. The analysis of the obtained solution enables us to find the range of the contact parameters, such as the electrical and thermal properties of a contact material, current, voltage, opening velocity, in which either term is dominating. Some experimental data are analysed for the illustration of the obtained estimations.