What is the typical purpose of a control relay in a limited-energy circuit?

• A. To switch higher-current loads from a low-energy control signal.
• B. To measure ambient temperature.
• C. To provide overvoltage protection.
• D. To terminate cables.

Answer: (A)

In limited-energy circuits, a control relay is used to drive higher-current devices from a small control signal. The relay coil is energized by the low-energy control circuit, and this energizes the relay contacts to switch the higher-current load circuit. This setup provides electrical isolation between the control side and the power side, protects the control equipment, and allows a small, safe signal to control a larger load.

The other options don’t fit because measuring ambient temperature is the job of a sensor, not a relay; overvoltage protection is provided by protective devices like fuses or surge suppressors; and terminating cables is done with connectors or terminations, not relays.