How potential relay works in refrigeration?

A potential relay operates on the voltage potential created by the induced voltage in the starting winding of the motor. It is an electromagnetic switch whose coil is wired directly in to the motor circuit. When power is applied to the circuit, the motor starts . As the motor attains its running speed the start winding acts as an auto generator and the voltage potential produced energizes the relay coil which cuts out the start capacitor and the start winding . The start winding still acts as an auto generator , however , and continues to produce enough power to keep the relay energized.