Break arcs in inductive circuits and the minimum arc current

A simulation method for voltage and current waveforms of break arcs in inductive circuits was developed. This method is based on Holm´s diagrammatical method. The minimum arc current (I_min) plays an important role, limiting the lowest value of the arc current. The calculation was carried out for a tungsten contact and compared with experimental results. The comparison has made it clear that the simulation method produces a fundamental error, so long as 1.0 A is used as the I_min of tungsten arc. Therefore, the break arc is examined for a current lower than 1.0 A. The use of a 0.4-A minimum arc current in this simulation method brought closer agreement with the experimental results, although 1.0 A is a characteristic current for steady and long duration break arc ignition