Arc discharge between thermally overloaded slot-channel walls

Increases in the voltage gradient of an arc with increases in current may be observed under special conditions. This phenomenon occurs both in moving and stationary arcs fired in a narrow-slot channel. It is shown that the voltage-gradient phenomenon is related to the thermal overload of the channel walls. This phenomenon may be utilised in order to obtain special surface properties of insulating materials. However, existence of the phenomenon may cause dangerous conditions in the arc-breaking chambers of switches, especially under conditions of multiple commutation. Formulas, for the calculation of the conditions in a channel where a further increase in thermal load provokes changes in the active surface properties of the walls, are given.