Arc Characteristics and Electrode Mass Change of AgNi Contacts for Electromagnetic Contactors

Recently, photovoltaic power systems and electric vehicles have been getting popular. Therefore, the importance of DC switching is expected to be getting larger in near future. The authors have been examining an evaluation method of the electrode loss of AgNi contacts for a electromagnetic contactor with medium DC load current at a resistive circuit. Consequently the relation between arc energy and cathode loss has been made clear. In this paper, arc energy and electrode mass change are investigated in more details. The experiments are carried out mainly under various normalized contact loads of 0.5, 0.75, 1.0 (nominal value 2.0N), 1.25 and 1.5. Consequently, it can be made clear that an arc duration is almost the same, about 3.5ms at all contact loads. And the contact resistance increases with the contact load. Further, the relation between contact mass change and arc energy is experimentally obtained. The cathode loss per unit arc energy is almost the same, about 0.06μg/J at all contact loads.