Potential relays are often used in reverse cycle units; what is true about them?

The most accurate statement regarding potential relays, particularly in reverse cycle units, is that the contacts are normally closed (NC). Potential relays play a crucial role in the operation of compressors, particularly in starting conditions.

When the compressor operates, the relay senses the voltage potential of the start winding. Once the compressor reaches a certain voltage, the relay opens, disconnecting the start winding and allowing the compressor to run on its run winding. In this case, the contacts being normally closed means that they remain closed until a specific voltage threshold is reached, which ensures the start winding is engaged initially to kick-start the compressor.

Understanding the relay's function in controlling compressor operation and the nature of its contacts helps clarify its essential role in efficient unit performance and protection against potential failures.