Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What device is commonly used to control a motor with overload protection?

1. Relay

2. Contactor

3. Line starter

4. Transformer

The correct answer is: Line starter

The commonly used device to control a motor with overload protection is a line starter. A line starter is specifically designed to enable motor starting while simultaneously providing overload protection. It typically includes a combination of a contactor, which controls the power to the motor, and overload relays that automatically disconnect the motor from the power supply in the event of an overload condition. This prevents damage to the motor and ensures safe operation. In contrast, while relays and contactors are important components in electrical systems, they do not inherently provide overload protection on their own. A relay may control various electrical devices but lacks the added protection features of a line starter. Contactors serve to switch electrical circuits on and off but require an overload protection device to ensure safe operation of motors. A transformer, on the other hand, is used for stepping voltage up or down but does not control motors or provide overload protection. Therefore, a line starter is the correct choice for controlling a motor with built-in overload safety features.