The Siemens 3RN1010-2BB00 is a thermistor motor protection evaluation unit from the SIRUS 3RN1 series, designed to monitor PTC thermistor sensors embedded in motor windings. It operates on 24 V AC/DC supply and provides two changeover (CO) contacts for signaling or direct trip of the motor contactor.
The 24 V AC/DC coil is universal for control transformers or DC supplies common in modern panels. The two CO contacts (rated for 50/60 Hz auxiliary circuits) handle the motor contactor coil and a remote alarm — no NC or NO auxiliary contacts are provided beyond the two COs. The LED display confirms trip status locally. The 91 mm depth and 94 mm height fit standard enclosures. RoHS compliance is dated to May 28, 2009, covering the EU directive. No UL or CSA marks are listed in the spec record — confirm with the successor if regulatory listing is required for your jurisdiction.