Modelling of energy transport in arcing electrical contacts to determine mass transfer

This paper presents a model which calculates the amount of erosion of an electrical contact undergoing arcing for a range of contact opening conditions. The model assumes all vaporised material is lost from the contact and is related to the energy received by the contact. It is proposed that two processes occur which transport energy to the contact surface from the arc discharge. These have been called the Radial Transport Process and the Channelled Transport Process. Calculations at different ratios of the transport processes are compared to experimental data at 9A, 64V DC. The modelling procedure consists of several stages: (a) the arc discharge is divided into three regions which generates energy for dissipation; (b) the energy from each region is dissipated through the arc and delivered to the contact surface by Radial/Channelling Transport Processes; (c) heat flow through the contact from the surface is calculated using an explicit numerical finite difference scheme dependent upon energy input, contact dimensions and material properties-this is then used to determine the temperature gradient of the surface and any phase changes; (d) knowing the condition of the contact surface, and contact separation, the erosion/deposition rate is calculated assuming all evaporated material is removed from the surface.