Several safety devices protect the compressor in abnormal situations. For instance, the high pressure switch interrupts the compressor control circuit when the refrigerant high-side pressure becomes excessive. A low pressure switch interrupts the compressor control circuit when the refrigerant low-side pressure becomes too low. The compressor is protected from overloads by current-operated circuit breakers. Thermal devices embedded in the windings of the compressor motor open the circuit when too much heat is generated by the windings. Some manufacturers place a 5-min delay device in series with the compressor motor. Thus, the motor cannot be restarted for 5 min after shutdown.
When any of the above safety devices are actuated, current in the Y1 leg is interrupted and shuts off the compressor and condenser fan motors.