Theoretical and experimental determination of erosion rate due to arcing in electrical contacts

Erosion rate of electrical contacts is a very important parameter to understanding and evaluating the performances of contact materials and switching devices such as the life time. The most common measurement of arc erosion is the mass change of the contacts, determined by the weighing of the anode and the cathode, before and after the electrical tests. The erosion is well known to be a transfer from the anode to the cathode then from the cathode to the anode and finally a bilateral loss takes place. In this work, and to avoid the transfer phenomena, the mass of electrode after a large number of breaking operations is performed in the domain of bilateral erosion of the anode and cathode. Calculation of the evaporated mass by finite element simulation of thermal input and heat transfer to the electrode from the arc is made. It is found that the evaporated amount per unit of duration arc is in agreement for silver materials but for metal oxide it needs the knowledge of material properties and namely data of physical heat conduction.