The Siemens 3UG4618-2CR20 is a SIRIUS phase and network monitoring relay with digital setting. It monitors AC three-phase systems for phase loss, phase sequence, asymmetry, and overvoltage, with adjustable thresholds via the LCD display. Rated for 90-400 V AC at 50/60 Hz, the output contacts switch 3 A at 250 V or 400 V (resistive). The 22.5 mm wide housing snaps onto a DIN rail, and the operating range covers -25 to +60 °C.
What the ratings mean for fit
The 90-400 V AC rated range covers both 208 V and 400 V three-phase networks common in industrial panels. The 3 A contact rating at 250/400 V is sized for signaling to a PLC input or contactor coil, not motor switching. Asymmetry detection and overvoltage monitoring are built in, with the LCD showing the set point and fault status. The 22.5 mm width fits a standard single-module slot; clearance is needed above and below for wiring (103 mm height, 91 mm depth). IP20 means it's for enclosure use only.