The Siemens 3RN1012-1CB00 is a thermistor motor protection evaluation unit — a relay that monitors PTC sensor chains in motor windings and trips on overtemperature. It runs on 24 V AC/DC supply, with one NO and one NC contact for alarm or trip signaling, and includes a reclosing lockout function to prevent automatic restart after a fault. The LED display gives a local status check without needing a panel HMI.
Mounting & Panel Fit
Housing is 22.5 mm wide — single modular unit on DIN rail. Fastening method is screw and snap-on mounting, so it clips onto the rail and can be screwed down for vibration resistance. That 91 mm depth is the body; leave clearance for wiring at the screw terminals. IP20 means it's fine inside a closed cabinet but not for open-panel dust or washdown. Ambient range of -25 to +60 °C covers most mill and crusher enclosures without derating.