Harmony Control. This mains monitoring relay monitors three-phase networks (200-240 VAC) for phase sequence, phase failure and undervoltage. Two relay changeovers are available for reporting, which can be loaded up to 8 A. The limit value for undervoltage (-20--2%) can be set. The settings are made using controls on the front, which can be protected against changes under a transparent cover. An illuminated scale arrow makes it very easy to see the setting of the potentiometers, even from a distance. The diagnostic switch on the front enables the output relays to be switched off to test the entire application. When the transparent cover is closed, the diagnostic switch is automatically reset. Three LEDs show the status. The width is 22.5 mm and it is mounted on a top hat rail. The cable is connected using screw terminals.