The Siemens SIRIUS 3UG4633-1AL30 is a voltage monitoring relay with digital setting, designed to keep a close watch on single-phase AC/DC supplies from 17 to 275 V at 50/60 Hz. The relay output is a single changeover contact rated 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V — enough to signal a PLC input or drive a small contactor coil. The LCD display gives you a local readout of the measured voltage and parameter settings, which is handy during commissioning or fault-finding without needing a meter.
The 17-275 V AC/DC rated range covers most standard control voltages in industrial panels — 24 VDC, 48 V, 110 V, 230 V — without needing a different relay for each. The 1 % repeat accuracy means if you set the undervoltage trip at 200 V, it will trip at 200 V every time, not drift 5-10 V with temperature or over time. That matters when you're coordinating with downstream contactor hold-in thresholds or UPS transfer settings. The 22.5 mm width and snap-on mounting (DIN rail) let it fit in a standard 8-module row alongside breakers and contactors. IP20 protection means it's for use inside an enclosure, not out on the wet floor.
The relay includes auto-reset and external reset options, and a configurable start-up delay (0.1 to 20 s) to ride through momentary dips during motor starting or generator transfer. That flexibility means it can often replace an older fixed-threshold relay without rewiring the panel.