Non-damage fuse operations on 11kV overhead lines

Most 11 kV overhead line fuses are connected to spurs beyond a ground mounted circuit-breaker or, beyond a pole mounted circuit-breaker that is being operated as a source circuit-breaker. Group fusing, as above, has replaced the use of fuses in series and, largely, the fusing of individual transformers. However, even with group-fusing and the wide implementation of auto-reclosing, most fuse operations are still nondamage. The task for the fuse is that it should operate when the circuit-breaker recloses if a fault remains on the spur. Simple as this seems, it requires the circuit-breaker to operate before the fuse for the first protection operation, but the fuse to operate before the circuit-breaker for the second. The difficulty of placing the fuse characteristic between the instantaneous and delayed characteristics of the circuit-breaker is discussed by the author.