A mechanism for the fuse pre-arcing period

WHEN FAULT CURRENT FLOWS in a fuse element, the temperature distribution along the fuse wire, at the instant of melting, depends upon the fault magnitude and on the dimensions of the fuse cartridge. If the current is low, and near to minimum fusing current, and the cartridge dimensions are normal, or, if the current is high and the cartridge is very short, the distribution will assume a parabolic form, and melting will occur at the center of the wire. If the current is high and the cartridge dimensions are normal, or, if the current is low and the cartridge is very long, the distribution will have a rectangular form, and most of the wire will melt at the same time. The melting depends on current density and wire parameter.