The Siemens 3RN1012-2GB00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 family, designed to monitor motor winding temperature via PTC thermistors. It operates on a 24 V AC/DC supply and provides two CO (changeover) contacts for alarm or trip signalling. The unit is IP20 rated and mounts on a DIN rail via screw and snap-on fastening, occupying a 22.5 mm width — a single modular unit.
Key Ratings and What They Mean for Fit
The 24 V AC/DC supply is the control voltage for the internal electronics and relay coil — it must match your panel's control bus. The two CO contacts (no NC or NO contacts) are the only output; each CO can be wired as normally-open or normally-closed, giving flexibility for trip alarms or motor starter interlocks. The IP20 rating means it's protected against solid objects larger than 12 mm (fingers) but not against moisture — install in a clean, dry enclosure. The operating ambient range of -25 to +60 °C covers most industrial environments but not high-heat applications near ovens or furnaces without derating. Spring-loaded terminals accept solid or ferruled stranded wire, reducing wiring time compared to screw terminals.
Physical Fit and Mounting
The 22.5 mm width matches standard single-module DIN-rail devices — it occupies one slot in a panel. Depth of 91 mm and height of 103 mm are within typical enclosure depth allowances. The screw and snap-on mounting lets you clip it onto a 35 mm DIN rail without tools; the screw provides additional securement for high-vibration environments.