An Experimental Study of Influences of Contact Opening Speeds on Arcing Behaviors of Silver Contacts

摘要

In order to study the influences of contact opening speeds on break arc behaviors, Ag contacts were operated to break inductive DC load currents from 0.1 A to 2.0 A at 14 V with contact opening speeds of 1 mm/s and 10 mm/s in a switching mechanism employing a stepping motor. Occurrence rates of break arcs and their average durations were determined at each current level under the respective contact opening speeds. From the results, irrespective of the opening speed values, at the conventional minimum arc current level of 0.4A, the arc occurrence rates were almost 100% and the average arc durations were around 20 to 30 μs. This confirmed the author's previous observations in which the conventional minimum arc current level should be considered as the threshold level for arc discharges of certain duration to occur at the rate of almost 100%. The arc occurrence rates below 0.4A were slightly influenced by changes in the contact opening speeds. With respect to arc extinction gaps calculated by multiplying the average arc duration value and the contact opening speed value, it was found that with increasing the contact opening speeds, arc extinction gaps became larger, although they were on the order of several tens μm or less in the tested conditions.