The Model 455 three‑phase voltage monitor combines load and line‑side monitoring to alert the user of contact failure or impending contact failure. The line‑side monitoring will protect the motor from damaging line‑side conditions prior to the motor starting. With other line/load‑side voltage monitors, the motor must be started before a voltage problem is detected. With the Model 455, your motor is fully protected at all times. The motor will not start if a power problem is present.