What distinguishes contactors from standard relays?

• A. They are safety devices that trip on fault
• B. They are heavy-duty relays used for switching high-current loads and control large electrical loads like motor, lighting systems, or HVAC equipment
• C. They function as fuses
• D. They are miniature relays for signal lines

Answer: (B)

A contactor is designed for heavy-duty switching of high-current loads, while a standard relay is for smaller, signaling-type tasks. It’s built to carry large currents and handle the inrush and arcing that come with switching motors, large lighting banks, or HVAC equipment. The coil energizes to close the power contacts, and the device often features multiple poles to simultaneously switch several conductors (for example, three-phase motors). Because of this robust construction and higher current ratings, contactors are commonly used in motor starters and other load-control circuits, frequently paired with overload protection.

In contrast, fuses and circuit breakers are protective devices that interrupt fault currents, not devices designed to carry and switch large loads continuously. And miniature relays are intended for signaling and control of low-current circuits, not for switching high-power equipment.