Short-circuit current interruption in a low-voltage fuse with ablating walls

A computer simulated short-circuit current interruption in low-voltage fuses with no sand filling is described. The current interruption process in such fuses is aided by the ablation of the wall material of the fuse which helps to cool the arc column inside the fuse. An algorithm to solve the time-dependent energy balance equation for the arc column taking into account the ablation of the wall material and the consequent pressure rise inside the fuse was developed. The numerical algorithm is linked with the equations describing a test circuit to provide 1500 A of short-circuit current from a 250 V, 50 Hz source. Results suggest that the current interruption process is dictated by the temperature distribution in the arc column immediately after the explosion of the fuse wire. The most likely reason for the successful operation of the fuse is that most of the joule heating in the arc column immediately after the explosion of the fuse wire occurs in the outer regions of the arc column close to the wall of the tube.