The Siemens 3RN1011-1BB00 is a thermistor motor protection evaluation unit that monitors motor winding temperature via PTC thermistors. The enclosure is IP20 rated, sized at 22.5 mm wide by 102 mm high by 91 mm deep, with screw-type terminals for the auxiliary and control circuit.
The 24 V AC/DC rating covers both common control voltages, so the unit works in panels with either supply. Two CO contacts provide one normally-open and one normally-closed path per contact, enough to signal a trip to a PLC and latch a remote alarm. Reclosing lockout is built in — after a trip, the output stays open until the motor cools and the reset condition is met, preventing automatic restart that could damage windings.