The Siemens 3UG4511-1AN20 is a SIRIUS phase monitoring relay designed for single-function AC voltage supervision. It monitors a 160...260 V AC supply at 50/60 Hz and provides a single changeover contact rated at 3 A at 250 V or 400 V AC.
The rated supply voltage of 160...260 V AC at 50/60 Hz covers standard three-phase line-to-neutral or line-to-line monitoring in 230/400 V systems. The 3 A contact rating at 250 V AC (resistive) is sufficient for signaling to a PLC input or driving a small contactor coil; for higher loads, the relay should drive an intermediate contactor.
Snap-on mounting to a DIN rail. Terminals accept solid or stranded wire from 20 to 14 AWG (2 x 20...14 AWG for solid). The screw-type terminals are common for this class; strip length and torque values follow standard Siemens SIRIUS practice. No special tooling required.