The Siemens SIRIUS 3UG4511-1BQ20 is a single-function phase monitoring relay designed to supervise three-phase AC mains. It detects phase loss and incorrect phase sequence on supplies from 420 V to 690 V at both 50 Hz and 60 Hz, covering the common 480 V and 600 V industrial distribution voltages in North America and 400/690 V systems in Europe. For DC control circuits, the contacts handle 1 A at 24 V DC, 0.2 A at 125 V DC, and 0.1 A at 250 V DC — watch the DC derating curve if you're switching a DC-powered alarm circuit.
Dimensions are 22.5 mm wide, 92 mm tall, and 91 mm deep — a standard footprint that fits alongside other SIRIUS control gear in a panel. No mounting clearance is required at any side (0 mm upwards, forwards, backwards, downwards, and at the side), so you can pack modules tight. Terminals accept 2 x (20-14) AWG solid or stranded wire — that's 0.5 to 2.5 mm². The spring-cage or screw terminals (depending on variant) are sized for standard control wiring. Strip length is typically 8-10 mm; no special ferrules required for stranded wire in this gauge range.