The current-limiting power fuse

FUSES may be used on large central station and industrial systems in locations where a high interrupting capacity is required. The conventional fuse may clear a short circuit in a half cycle or several cycles. Associated apparatus is subjected to electromagnetic forces produced by the high momentary currents. Good engineering practice dictates that all disconnecting switches, contactors, motor starters, etc., shall have short-time current ratings at least equal to the initial root-mean-square fault current which the system is capable of producing at the point of installation. Where these currents are extremely high, a saving in size and expense of such apparatus can be effected if the required short-time current rating can be reduced. Many attempts have been made and accomplishment has been achieved by the use of a fuse which consistently limits the initial peak current to a fraction of that available in the circuit. The purpose of this paper is to describe the new fuse.