The Siemens 3RN1012-1BG00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 family. It monitors motor winding temperature via PTC thermistors and trips on over-temperature, with a reclosing lockout function that prevents automatic restart after a fault until manually reset. The unit is supplied at 110 V AC, rated identically for both 50 Hz and 60 Hz supply frequencies.
What the ratings mean for fit
The 22.5 mm width matches a single DIN-rail slot. Depth is 91 mm. IP20 housing is typical for control cabinets. Two CO auxiliary contacts are built in, with no dedicated NC or NO contacts. Screw-type terminals accept standard conductors. The operating ambient range of -25 to +60 °C covers most industrial enclosures without derating, though the upper end is tight for panels near ovens or direct sunlight. Mount away from heat sources if the cabinet ambient regularly exceeds 50 °C.
Integration notes
Mounting is by screw and snap-on to 35 mm DIN rail. The fastening method allows both permanent screw-fixing and tool-less snap-on for quick panel assembly. The unit carries a reference code K per IEC 81346-2, which classifies it as a contactor/relay function in the plant documentation system. The display version includes an LED for status indication. The substance prohibitance date of 05/28/2009 indicates RoHS compliance.