Littelfuse 455-575 Three-Phase Voltage/Phase MonitorLittelfuse 455 575 Voltage Monitor Product Description The 455 Series are 3 phase voltage monitors that combine load and line side monitoring to offer complete protection. Monitoring the load side will alert the user of contactor failure or impending contactor failure. Line side monitoring will also protect the motor from damaging fault conditions that may be present prior to the motor starting. With other line load side monitors, the motor must be