What distinguishes time-delay fuses from fast-acting fuses?

Time-delay fuses are specifically designed to tolerate temporary overload conditions without blowing immediately. This characteristic allows them to handle inrush currents, such as those experienced when electric motors start up, which can be significantly higher than the normal operating current. The ability to withstand these short-duration overloads helps prevent unnecessary interruptions in the circuit, making time-delay fuses ideal for applications where such inrush currents are common.

In contrast, fast-acting fuses are engineered to provide quick protection against overloads and short circuits, reacting almost instantaneously. While they effectively protect against excess current, their quick response means they may blow during temporary spikes that would not pose a lasting threat to the circuit or equipment. Therefore, in applications that experience brief surges in current, time-delay fuses are preferable due to their robustness in handling these conditions.