Which condition necessitates the use of time delay fuses in motor protection?

The use of time delay fuses in motor protection is essential for managing inrush currents during the startup phase of motors. When an electric motor is initially powered on, it can draw a significantly higher current than its running current. This surge, known as inrush current, can be several times greater than the normal operating current and can last for a short duration, typically just a few seconds.

Time delay fuses are designed to tolerate this temporary spike in current without blowing, allowing the motor to start without interruption. They provide the necessary protection against sustained overload conditions while still accommodating short-term increases in current that are typical during motor startup. This capability is crucial in preventing nuisance tripping or fuse failure, which could lead to unnecessary downtime in operations.

In contrast, other options address different scenarios that do not specifically relate to the need for time delay functions in motor protection. For instance, instantaneous circuit interruption refers to situations where fuses would blow immediately upon detecting excess current, which does not accommodate the startup inrush scenario. Continuous overload protection typically requires different types of fuses or protection devices that respond immediately to sustained overload conditions. The mention of gas appliances also pertains to a different category of equipment and does not connect to the need for time delay features in electrical motors