The Siemens 3RN1011-2GB00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 family. It monitors motor winding temperature via PTC thermistor sensors and trips the control circuit when the motor overheats, preventing damage. The unit operates on a 24 V AC/DC supply and provides two changeover (CO) contacts for signaling or direct contactor control.
Rated for 24 V AC/DC control supply — common in industrial panels, so it drops into existing 24 VDC architectures without a separate transformer. The two CO contacts handle both the trip signal and a remote indication, which saves an auxiliary relay in many applications. The unit measures 22.5 mm wide and 91 mm deep, fitting a single modular DIN-rail space. IP20 protection means it's suited for enclosed panels only — not washdown or outdoor locations.
The 22.5 mm width leaves room for adjacent modules in a crowded panel. Spring-loaded terminals accept ferruled or solid conductors; strip length is 8 mm. The reclosing lockout feature prevents automatic restart after a trip — critical for applications where a manual reset is required by code or process safety.