The fuse must have a voltage rating equal to or greater than the normal frequency recovery voltage which will be seen across the fuse under all
conditions. On three-phase systems, it is a good rule of thumb that the voltage rating of the fuse be greater than or equal to the line-to-line voltage of the
1. General Purpose Current-Limiting Fuse: A fuse capable of interrupting all currents
from the rated interrupting current down to the current that causes melting of the
fusible element in one hour.
2. Back-up Current-Limiting Fuse: A fuse capable of interrupting all currents from the
maximum rated interrupting current down to the rated minimum interrupting current.
3. Expulsion Fuse: A vented fuse in which the expulsion effect of gasses produced by
the arc and lining of the fuse holder, either alone or aided by a spring,
extinguishes the arc.