What is another name for a start relay used in HVAC systems?

A start relay, often found in HVAC systems, is primarily referred to as a potential relay. This type of relay is specifically designed to help start the compressor by using the potential difference (voltage) across a secondary winding in the compressor’s motor.

When the compressor is energized during startup, the potential relay utilizes the voltage across this secondary winding to determine if the motor has started. If the current levels drop to a certain threshold after startup, the relay will disconnect the starting circuit, allowing the compressor to operate efficiently without the start capacitor.

Understanding the function and naming convention of the potential relay is essential for HVAC technicians. It emphasizes the importance of monitoring voltage changes in the system, which is crucial for ensuring that the compressor operates smoothly and reliably. This concept also differentiates the potential relay from other types, such as current relays, which respond to the current flow, or voltage relays, which might operate on specific voltage levels but are not specifically tailored for starting motors in the same way.