The Siemens 3RN2010-2BA30 is a SIRIUS 3RN2 thermistor motor protection relay — a standard evaluation unit designed for bimetallic switch sensors. It monitors motor winding temperature via PTC thermistors and trips the output when the resistance threshold is crossed, protecting against overtemperature. Rated supply is 24 V AC/DC (50/60 Hz), and the relay provides a 1 A output at 24 V or 0.2 A at 125 V. It features automatic reset after the fault clears, with no external reset or error memory. IP20 protection suits clean, dry control cabinet environments.
The 1 A at 24 V output is the relay contact rating for the load circuit — enough to drive a contactor coil or a small PLC input. At 125 V the rating drops to 0.2 A, so if you're switching a 125 VDC pilot light or valve, confirm the inrush stays under that. The response threshold is set by the thermistor loop: the relay trips when the PTC resistance exceeds the full-scale value of 1.1 (relative to the initial value of 0.85). That 9 % relative metering precision means the trip point is tight enough for reliable motor protection without nuisance trips.
Substance prohibitance compliance is documented per the 05/28/2009 date — this covers RoHS and REACH requirements for the European market. No UL or IEC certification numbers are listed in the spec record, but the SIRIUS line typically carries IEC/EN 60947 approvals; verify with the datasheet for your specific application.
Accepts solid or stranded wire from 20 to 12 AWG (0.5 to 2.5 mm²). The terminal layout is standard for the 22.5 mm housing; allow 0 mm clearance on all sides (up, down, forward, backward, sideways) per the spec — meaning it can be packed tight against other modules. Galvanic isolation exists between input and output, and between the outputs themselves — important for separating the thermistor loop from the control circuit. The LED display gives local status indication.