Differentiate a contactor from a relay.

• A. A contactor is designed to switch high-current circuits and typically handles motor loads; a relay switches low-current signals.
• B. A contactor is designed to switch low-current signals; a relay switches high-current motor loads.
• C. A contactor cannot switch AC loads; a relay can.
• D. A contactor includes built-in overload protection; a relay does not.

Answer: (B)

The key idea is that contactors are heavy-duty switches designed to control high-current loads, especially motors, while relays are smaller devices intended to switch low-current control signals. A contactor is built to handle the electrical demands of starting and running motors, including inrush currents, with robust contacts and multiple poles. A relay, on the other hand, is typically used to switch low-current circuits such as sensors or logic inputs and isn’t meant to power motors directly. That’s why the description stating that a contactor handles high-current motor loads and a relay handles low-current control signals fits best. The other statements aren’t generally true: contactors can switch AC loads, overload protection isn’t universal to all contactors, and relays can also switch various loads, including some motor-related control circuits, depending on design.