The Siemens 3RN1012-2CB00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 series, designed to monitor motor winding temperature via PTC thermistors and trip on over-temperature. It operates on 24 V AC/DC control voltage and provides one normally open plus one normally closed auxiliary contact.
The 3RN1012-2CB00 is listed as a current-production part, but the manufacturer designates it as a phased-out product with a preferred successor: the 3RN2012-2BA30. The successor maintains the same 24 V AC/DC supply, 1 NO + 1 NC contact arrangement, and spring-loaded terminal type, but adds Manual/Auto/Remote operating modes. For new BOM lines or panel designs, the 3RN2012-2BA30 is the recommended drop-in replacement.
Its 22.5 mm width (one modular unit) and 91 mm depth fit standard control-panel layouts without crowding adjacent devices. All auxiliary and control circuit connections use spring-loaded terminals, which speed wiring and reduce the risk of loosening under vibration compared to screw terminals.
The part carries a RoHS compliance date of May 1, 2012, and is assigned reference code K per IEC 81346-2, indicating a control relay or protection function in system documentation.