The Siemens 3UG5512-1AR21 is a line monitoring relay from the SIRIUS family, designed to supervise three-phase mains supplies. It detects phase failure, incorrect phase sequence, and asymmetry conditions across a supply range of 3x 160-690 V AC at 15-70 Hz, outputting a single changeover contact via screw terminals.
The 160-690 V AC operating range covers standard low-voltage networks from 208 V to 600 V nominal, including 400 V and 480 V systems common in industrial panels. The single changeover contact (SPDT) is rated for signal-level switching to a PLC digital input or contactor coil; it is not a power-switching contactor. Screw terminal connection matches existing panel wiring practices. The packaging dimensions of 128 x 109 x 33 mm give a compact footprint for DIN-rail mounting, leaving room alongside motor starters or distribution blocks.
RoHS compliance is effective from June 1, 2023, meaning units manufactured after that date meet the substance restrictions. The REACH declaration identifies lead above the 0.1% threshold, which is typical for certain internal solder joints or contact materials in this class of relay.