An experimental study of the minimum arc current of silver contacts with different opening speeds

Abstract

In order to study the influence of contact opening speed on occurrence rates of break arcs, Ag contacts were operated to break inductive DC load currents from 0.1 A to 0.6 A at 14 V with contact opening speeds of 0.5 mm/s to 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, the arc occurrence rate was almost 100% at 0.4 A. For all of the contact opening speeds tested, the conventional minimum arc current level can be considered, not as the lower limit for arc ignition, but rather as the threshold level for arc discharges of certain duration to occur at the rate of almost 100%. Moreover, in the current range from 0.2 to 0.4A, slight differences in the arc occurrence rates were seen with differences in the contact opening speeds. The average arc durations were around 50 ps at the conventional minimum arc current level of 0.4 A, and not influenced significantly by changes in the tested range of contact opening speeds.

An Experimental Study on Minimum Arc Current for Arcs Longer Than a Few Microseconds in Relay Contacts and Possible Reinterpretation of the Meaning Thereof

“…Further studies are being conducted with various contact opening speeds by means of a different switching apparatus that employs a stepping-motor-driven stage to investigate influences of contact opening speeds on arc occurrence characteristics and obtain better understandings of minimum arc current [11]. Investigations in view of arcing currents will be also planned in the future.…”

Simulation of arcs for DC relay considering different impacts

“…In [3] and [4], the impact of magnetic field on DC breaking process was analyzed by experiments. Other researchers compared the arc behaviours under different contact opening speeds in [5][6][7]. It is still difficult to obtain intuitive behaviours and detailed parameters of arc.…”