What type of fuse are Type SC fuses rated at 20 amps and above?

Type SC fuses rated at 20 amps and above are classified as time delay fuses. This type of fuse is designed to withstand temporary overloads without blowing, which is crucial in applications where inrush currents may occur—such as starting motors or other heavy electrical loads. Time delay fuses allow brief surges of current to pass through while protecting the circuit from sustained overloads that could cause damage.

In contrast, fast blow fuses would trip immediately at their rated current, providing less tolerance for fleeting surges, which is not suitable for applications that involve motor starts. Instant blow fuses function similarly by cutting off power immediately upon reaching their rated capacity, thus lacking the delay feature. Although rejection type refers to a specific design that prevents incorrect installation—ensuring that only compatible fuses are used—it does not classify the operational characteristics regarding current ratings. Hence, time delay fuses are the correct choice for this scenario because they provide necessary protection while accommodating normal operational conditions that may cause temporary high current draw.