Effect of harmonic currents on semiconductor fuse ratings

In power electronic applications, proximity and skin effects cause an increase in the resistance of fuse elements and possible unequal sharing of the total current between multiple parallel elements. In this paper the current density distribution is calculated for typical arrangements of fuse strips as a function of frequency, and methods of de-rating the fuse are discussed. The calculations are done using an equivalent wire-grid array method. De-rating factors are calculated for sinusoidal and some nonsinusoidal waveforms commonly found in power electronic applications. The implications for the design of semiconductor fuses for HF applications are also considered.