Phase monitoring relay with LCD and IO-Link
The Siemens SIRIUS 3UG4815-1AA40 is a network monitoring relay that tracks phase sequence, phase failure, and asymmetry on three-phase AC supplies. It combines five monitoring functions in one 22.5 mm housing, with an LCD for local readout and IO-Link COM2 (38.4 kBaud) for parameterization and diagnostics into a PLC or higher-level system. Rated operational current is 3 A at 250 V and 400 V at 50/60 Hz, which covers the typical control-circuit contactor coil or alarm load. The relay detects asymmetry and can be set for auto-reset or external reset, with a configurable start-up delay up to 999.9 s to ride through motor inrush or generator ramp-up.
Mounting and wiring
Snap-on mounting onto 35 mm DIN rail; the 22.5 mm width and 91 mm depth fit standard control-panel layouts. Mounting position is any, so it works in tight enclosures or vertical busways. Terminal capacity accepts 2x (20–14) AWG solid or stranded, with zero clearance required on all sides — no derating for side-by-side installation. IP20 protection class means it is suited for dry indoor panels only; no washdown or dust ingress protection. Pollution degree 2 is the standard for normal industrial environments with non-conductive contamination.