The Siemens SIRIUS 3UG4512-1AR20 is a phase monitoring relay that monitors three-phase AC supplies for phase loss and phase sequence. The output relay contacts are rated for 3 A at 250 VAC or 400 VAC at 50/60 Hz, and for DC loads: 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V. This covers most control-circuit and small auxiliary load switching.
Key Ratings in Context
The relay offers automatic reset after fault recovery, which is useful for unattended installations where manual reset is impractical. It does not detect asymmetry, overvoltage, or undervoltage — it is a phase-loss and phase-sequence monitor only. The depth is 91 mm, height 83 mm, and the unit requires 0 mm clearance on all sides (up, down, forward, backward, side) — no ventilation gaps needed.