Which type of relay provides 3-phase power to a motor circuit?

The correct choice is a contactor, which is a specialized type of relay designed to switch large amounts of electrical power. Contactors are particularly suited for controlling motor circuits and can handle the demands of three-phase power systems used for industrial and commercial motors.

The primary function of a contactor is to open or close the circuit in response to an electrical signal, allowing or interrupting the flow of electricity to the motor. Unlike basic relays, contactors are built with higher current ratings and additional features such as auxiliary contacts for controlling other devices and overload protection. This makes them ideal for starting and stopping motors, as well as for safety applications in three-phase power setups.

In contrast, other types of relays, such as single-coil relays or mechanical relays, are generally used for lower power applications and do not have the capacity to handle the power levels required for three-phase motors. Auxiliary relays typically serve to enhance control logic in a circuit rather than directly controlling power to high-current devices like motors. This distinction highlights why the contactor is the appropriate choice for providing three-phase power to motor circuits.