The Siemens 3UG4631-2AA30 is a SIRIUS voltage monitoring relay with digital setting, designed to detect both overvoltage and undervoltage conditions on AC or DC systems. It operates at a rated value of 24 V (50/60 Hz) and offers a measurable voltage range from 0.1 to 60 V AC, making it suitable for monitoring control supply rails or low-voltage distribution. The relay snaps onto a standard DIN rail (22.5 mm width, 94 mm height, 91 mm depth) and is rated IP20, so it belongs inside a panel enclosure. The LCD display shows the measured value and setpoints, and the 1 % relative repeat accuracy means the trip thresholds stay tight across temperature swings.
The relay's output contacts are rated 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V. These are not motor-switching ratings — they drive PLC inputs, contactor coils, or signal lamps. If your load draws more than 0.1 A at 250 V, you need an interposing contactor. The full-scale value is adjustable from 0.85 to 1.15 times the rated value, so at 24 V you can set the trip window between 20.4 V and 27.6 V. The undervoltage and overvoltage detection are independently enabled, and the relay supports both auto-reset and external reset via a remote pushbutton or PLC digital output.
Mounting position is any orientation, so it fits in tight sub-panels or vertical bus drops. The spring-cage terminals accept 0.2–2.5 mm² (24–16 AWG) solid or stranded wire, and the strip length is 8 mm.