What it is and what it does
The Siemens 3UG4617-2CR20 is a SIRIUS network monitoring relay — a phase monitoring relay with digital setting and an LCD display. It monitors three-phase AC supplies for phase loss, phase sequence, asymmetry, and overvoltage, with a rated voltage range of 160 to 690 V at 50 or 60 Hz. The output contacts are rated 3 A at 250 V and 400 V (50/60 Hz), with lower ratings for DC loads: 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V. That means the relay can switch small motor starters or signal lamps directly, but for larger contactor coils you'd want an interposing relay. Asymmetry detection and overvoltage detection are built in, with a configurable auto-reset function. The LCD gives you a local readout of the measured values and settings — no separate display module needed.
Panel fit and wiring
The housing is 22.5 mm wide, 94 mm high, and 91 mm deep — a standard single-module width for DIN-rail enclosures. Snap-on mounting to 35 mm DIN rail, and the mounting position is any orientation. Clearance around the unit: 0 mm on all sides (up, down, forwards, backwards, sideways), meaning it can be packed tight against other devices without derating. Terminals accept solid or stranded wire from 24 to 16 AWG (2x per clamp). The IP20 protection class means it's safe for finger contact in a closed panel but not for washdown environments.