What crucial feature distinguished Thomas E. Murray's practical electric fuse design?

incorporation of a time-delay mechanism

The incorporation of a time-delay mechanism was the crucial feature that significantly distinguished Thomas E. Murray's practical electric fuse from earlier, simpler conceptual weak links in a circuit. This feature was necessary because electrical systems frequently experience brief, momentary current surges, often caused by inductive loads like motors starting up. A device that tripped instantly on these harmless spikes would be functionally impractical. Murray’s innovation allowed the fuse to tolerate these short, high-current events without blowing, yet still activate rapidly enough to protect the system from sustained, dangerous overloads or short circuits. This controlled response capability established the utility of the practical fuse.