A.C. short-circuit performance of uniform-section fuse elements

An analysis is made of the heating of uniform-cross-section fuse elements or conductors by a.c. short-circuit currents. Taking as reference the current that produces melting in one half-cycle, the analysis is developed in terms of dimensionless parameters. Generalised forms of the prearcing time/current, cutoff, and inductive-energy characteristics are presented, which are valid for any fuse element in any circuit. The a.c. short-circuit performance of notched fuse elements is described in a companion paper.