Minimization of arc extinction gap in the opening speed range 1 cm/s - 1 m/s

Speed separation in switches and relays is a fundamental parameter to improve breaking devices performances by reducing extinction gap and arc duration. It is commonly admitted, that with resistive load, high speed separation produces lower arc duration and keeps constant extinction gap, whereas with inductive load, the extinction gap is enlarged. The objective of this paper is to minimize the gap in a wide opening speed range (from 1 cm/s to 1 m/s) covering the main application of breaking and disconnecting devices. The results reveal a minimum arc extinction gap that occurred at an opening speed close to a few cm/s. Contrary to the common idea, this new result shows that high separation speeds are not always required to minimize the gap. In addition, this minimum gap value is highly affected by load and current, while contact materials seem to have a minor action. Based on arc shape and plasma examination, some attempts are made to explain this gap contraction.