Arc mobility on bouncing contacts

The arc mobility on eroded Ag/CdO and three different Ag/SnO/sub 2/-contacts during bounces simulated in a model switch was investigated with the aid of a two-dimensional (2-D) optical arrangement. The high apparent arc mobility observed on two of the Ag/SnO/sub 2/-materials investigated was caused by arc commutation inside the contact gap. Ag/CdO and another Ag/SnO/sub 2/-material showed both arc creeping and arc commutation-but only very close to the site of arc ignition. No continuous fast arc motion occurred in short bounce gaps (0.18 mm, corresponding to bounce values in modern contactors) whether or not a magnetic blast field has been applied, There was no correlation between the amount of contact erosion at make and the apparent arc mobility observed on certain materials.