Which device is designed to switch heavy electrical loads under control of an electromagnetic coil?

• A. Breaker
• B. Relay
• C. Contactor
• D. PLC

Answer: (C)

A contactor is built to switch heavy electrical loads under the control of an electromagnetic coil. When the coil is energized, it creates a magnetic field that pulls in a set of large, high-current contacts, allowing or interrupting the flow to motors and other power equipment. This makes it ideal for remote or automatic control of heavy loads in industrial settings.

Relays also use coils to operate contacts, but they are typically used for lighter, signal-type currents rather than the heavy currents a motor or large heater requires. Breakers protect circuits by interrupting fault currents and aren’t designed for routine switching under control of a coil. A PLC provides the control logic and can drive contactors or relays, but it isn’t the device that directly carries the heavy load.