Current-Limiting Fuse with Full-Range Clearing Ability

High-voltage current-limiting fuses inherently have had difficulty in interrupting very low currents, 1 to 5 times fuserated current. Thus, some auxiliary coordinated device was always required to provide the interrupting function at low-current range. The primary reason that current-limiting sand-filler fuses encounter low-current clearing problems is the unbalance of voltage stress produced along the length of the fulgurite formation by leakage currents within its vitrified section. The difficulty now can be overcome by incorporating a gas-evolving element support within the fuse. Further improvement is achieved by proper placement of arc electrodes which produce multiple arc regions under low-current element melting, with a reduction in total arc energy released, plus an improved energy distribution within the fuse.