Harmony Control. This voltage monitoring relay monitors three-phase supplies 208-480 VAC (50-60 Hz) for phase failure, as well as exceeding or falling below an adjustable limit value. A relay changer is available for reporting, which can be loaded up to 5 A. The two limit values and a switch-off delay are adjustable. The settings are made using control elements on the front, which can be protected against changes under a transparent cover. Two LEDs show the status. The device is powered by the measuring voltage. The width is 17.5 mm and it is mounted on the top hat rail.