The Siemens 3RN1000-1AG00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 family. It monitors PTC thermistor sensors embedded in motor windings and trips the control circuit when the winding temperature exceeds the sensor's rated response threshold, preventing thermal damage to the motor. The single changeover (CO) contact on the auxiliary circuit provides a normally-open and normally-closed signal path for the trip indication and reset logic. The 22.5 mm wide housing snaps onto DIN rail or mounts with screws, fitting standard control-panel layouts. IP20 finger-safe protection means it is suitable for installation inside an enclosed panel where personnel do not contact live parts during normal operation.
The 22.5 mm width occupies one standard modular-width slot on DIN rail. Screw and snap-on mounting gives the option to fasten directly to a panel backplate if DIN rail is not used. The IP20 rating means the unit must be installed in a cabinet or enclosure that provides the required environmental protection.