What is the function of a contactor in HVAC systems?

In HVAC systems, the contactor plays a crucial role in controlling power to heavy electrical loads, such as compressors and fans. A contactor is essentially an electromechanical switch that can handle high voltage and high current. When a smaller control voltage is applied, typically from a thermostat or control system, it energizes the coil within the contactor, causing it to close the contacts and allow current to flow to the connected load. This function is essential for the operation of HVAC equipment, as it allows for safe and efficient management of large electrical currents without exposing control circuits to potentially hazardous voltage levels.

The design of a contactor makes it suitable for cycling the power on and off to these heavy loads, ensuring reliable operation while providing protection against electrical overloads. Driving the compressor or other components in this manner is critical for an HVAC system's performance and longevity.

In contrast, increasing current flow, storing energy for motors, or measuring electrical resistance does not accurately represent the primary function of a contactor within HVAC systems.