A theory of abrupt termination and spontaneous restart of electrical current in surface flashover arcs

摘要

The spacehyphen;time dynamics of surface flashover discharges is studied using a nonlinear onehyphen;dimensional transmission line model. When the currentIis not zero, the relation between the resistance per unit length,Rcirc;, andIis assumed to be given by a local arc welderrsquo;s ansatz,Rcirc;Verbar;IVerbar;=East;, whereEast; is a constant. The model predicts a threshold for discharge, and abrupt local termination and spontaneous restart of the discharge current. If at a place on the discharge path it happens that the charge gradient fails to exceed the threshold condition when the current vanishes, then the current will abruptly terminate there. However, if a discharge current flows in a region adjacent to one where the current has terminated, the edge of the currenthyphen;free region can be lsquo;lsquo;ignited,rsquo;rsquo; resulting in the lsquo;lsquo;activersquo;rsquo; region encroaching on the lsquo;lsquo;quietrsquo;rsquo; one. A formula for the speed of encroachment is derived. Formulas are also derived for current pulse waveforms and the charge transported during the discharge.