Harmony COntrol. This voltage monitoring relay monitors single-phase supplies 20-80 VAC/DC (50-60 Hz) for exceedances and undershoots of an adjustable limit value in window mode. A relay changer is available for reporting, which can be loaded up to 5 A. The lower and upper 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 (nominal voltage 24-48 VAC/DC, 50-60 Hz). The width is 17.5 mm and it is mounted on a top-hat rail.