The Siemens SIRIUS 3UG4618-1CR20 is a network monitoring relay with digital setting, designed for AC phase monitoring. It detects phase asymmetry, overvoltage, and undervoltage across a 90-400 VAC range at 50/60 Hz. The relay provides a 3 A rated output at 250/400 VAC, suitable for signaling or direct control of downstream contactors. Housed in a 22.5 mm wide enclosure with snap-on DIN-rail mounting, it fits standard control panel layouts. The LCD display shows measured values and settings, with no separate LED display version. IP20 finger-safe terminals accept 2x (20-14 AWG) solid or stranded wire. The relay offers five selectable functions (phase sequence, phase failure, asymmetry, overvoltage, undervoltage) with a delayed switching option set to 2 seconds. Auto-reset is enabled by default, meaning the output re-energizes once the fault clears — useful for unattended restart in pump or fan applications.
Ratings and Environmental Limits
The auxiliary contact is rated 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V — these are the switching limits for the internal relay; the 3 A output at 250/400 VAC is the main load contact. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) means it is suited for industrial control panels without special coatings. Operating temperature range is -25 to +60 °C, storage and transport from -40 to +85 °C. Mounting position is any orientation, which simplifies panel layout. The 91 mm depth fits standard 100 mm deep enclosures with clearance for wiring.