The Siemens 3RN1011-1GB00 is a thermistor motor protection evaluation unit from the SIRIUS 3RN1 series, designed to monitor motor winding temperature via PTC thermistors and trip on over-temperature. It operates on 24 V AC/DC supply and provides two CO (changeover) auxiliary contacts for signaling or direct motor starter dropout. The IP20 protected housing uses screw-type terminals for auxiliary and control wiring.
This part is a phased-out product. The preferred successor is the 3RN2011-1BA30, which offers a manual/remote reset function and hard gold-plated contacts for improved low-voltage switching reliability. The 3RN2011-1BA30 also operates on 24 V AC/DC and maintains the same 2 CO contact configuration, making it a direct functional replacement for new designs or panel retrofits.
The 3RN1011-1GB00 includes a reclosing lockout function, preventing automatic restart after a thermal trip until the motor has cooled and a manual reset is performed. This is critical for applications where unexpected re-energization could cause equipment damage or personnel risk. An integrated LED display provides local status indication of the evaluation unit's operating state, simplifying commissioning and troubleshooting without needing a multimeter.