The Siemens SIRIUS 3UG4513-2BR20 is a network monitoring relay with analog setting, purpose-built to watch a three-phase AC supply for phase loss, asymmetry, and undervoltage. It's the kind of part you spec into a motor control center when you want one device to cover the basic power-quality checks without a PLC doing the math. Rated input spans 160 to 690 V AC at both 50 and 60 Hz, so it handles everything from a 208 V feeder up to a 600 V industrial bus without a tap change. The output contacts are rated 3 A at 250 V and 400 V, 50/60 Hz — enough to kick a contactor coil or signal a PLC input directly. Snap-on mounting to a DIN rail, 22.5 mm wide. IP20 finger-safe terminals.
The 160-690 V AC range covers common low-voltage three-phase systems. The analog dial adjusts the trip point as a percentage of nominal voltage; initial value is 1. Asymmetry detection is built in. Output contacts are rated 3 A at 250 V and 400 V AC, but derate for DC loads: 1 A at 24 V, 0.2 A at 125 V, 0.1 A at 250 V. If you're switching a DC coil or a PLC input, keep the DC curve in mind — the AC rating doesn't carry over. Auto-reset is enabled by default (yes, it's listed). That means after a fault clears, the relay re-energizes automatically — good for unattended sites, but if you need manual reset for safety, check the wiring config. Delayed switching is set to 2 seconds, giving a brief ride-through for momentary dips.