HOLT Electricians Practice Exam

What type of fuse is typically used for overload protection in motors?

1. Time-delay fuse

2. Dual-element fuse

3. Circuit breaker

4. Standard fuse

The correct answer is: Dual-element fuse

The type of fuse that is typically used for overload protection in motors is the dual-element fuse. This fuse combines both time-delay and regular fuse characteristics, making it ideal for handling the inrush current that motors experience during startup. When motors are powered on, they may draw several times their normal operating current for a short period—this is known as inrush current. A dual-element fuse allows for this temporary overload without blowing immediately, thus providing necessary protection while accommodating the motor's normal operating conditions. In addition to its time-delay feature, the dual-element construction provides a means to protect against sustained overloads, enabling it to blow if the motor runs under heavy load for longer than it should, which could potentially cause damage. This selective protection is essential in maintaining operational efficiency and safeguarding equipment and personnel. While other fuses like time-delay fuses may also offer some level of overload protection, dual-element fuses are specifically designed for motor applications and are widely preferred for their effectiveness in handling the unique electrical characteristics associated with motor loads.