Performance and arcing characteristics of Ag/Ni contact materials under DC resistive load conditions

Silver alloys used in medium duty switching devices exhibit low erosion and anti-weld characteristics along with good electrical and thermal properties. Silver metal-oxides (Ag/MeO) are extensively used as a contact material and silver nickel (Ag/Ni) is also employed that can exhibit improved features in given conditions. Erosion and arc characteristics of Ag/Ni contact materials under DC break conditions, 1-16-A, are presented and these demonstrate several features. (i) Close to 100- of all eroded cathode material is deposited onto the anode. (ii) A cathode mass loss for Ag/Ni appears to be similar for other Ag/MeO materials tested and is a linear function of arc energy. (iii) The resistivity per cross-sectional area of the arc, as the arc is drawn between the opening contacts, is found to be approximately constant during the metallic ion phase of the arc. (iv) With arc resistivity per cross-sectional area assumed to be constant during the metallic ion phase, the arc length on ignition can be determined. This is found to be 0.40±0.02-mm for the 4-A study of the Ag/Ni material.