A.C. short-circuit performance of notched fuse elements

The heating of notched fuse elements under a.c. short-circuit conditions has been studied, using finite-difference methods to solve for the transient current and temperature distributions in the element. The method gave good agreement with experimental results. A comparison of the behaviour with that of a uniform-section element described in a companion paper shows that there are significant differences. In particular, the notched element shows large discontinuities in the time/current characteristic, and a wide variation in prearcing I2t, depending on the circuit parameters.