Full range current limiting fuse to clear high and low fault currents

摘要

An improved high voltage, full range, current limiting fuse with enhanced ability to dear high and low fault currents, even after the fuse has been subjected to a potentially damaging current surge, includes a sand-filled tubular housing with conductive terminals at either end and a dielectric support member supported therein about which a fusible structure is spirally wound. The fusible structure is electrically connected to the terminals and includes one or more high fault current interrupting elements for clearing high fault currents to which is mounted a low fault current interrupting assembly. The low fault current interrupting assembly includes a plurality of conductive components one of which is a damage sensor portion having a melting time-current characteristic which results in the damage sensor portion melting before the one or more high fault current interrupting elements. This enables the fuse to interrupt a low current which might exist after an element-damaging surge has occurred. A thermal shield mounted to the housing adjacent the low fault current interrupting assembly prevents damage to the housing caused by arcing in the low fault current interrupting assembly.