The Siemens 3RN1010-2BG00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 series. It monitors motor winding temperature via PTC thermistors and trips the control circuit when the motor overheats. Rated for 110 V AC supply at both 50 Hz and 60 Hz, it fits a standard 22.5 mm DIN-rail slot and connects via spring-loaded terminals — no screwdriver needed for the control wiring.
The 22.5 mm width matches the slim footprint of other SIRIUS control gear, so it tucks into a crowded DIN rail without eating up space. The unit carries two CO (changeover) auxiliary contacts for signaling the PLC or a contactor coil. The LED display gives a quick visual of trip status — handy when you're walking the line and don't want to break out a meter.
The unit carries a RoHS compliance date of May 28, 2009, meaning it meets the EU RoHS directive for substances. No UL or CSA markings are listed in the spec record, so verify with your local code if those are required.