The Siemens SIRIUS 3RN2010-1BA30 is a thermistor motor protection relay from the 3RN2 family, designed to monitor PTC thermistor sensors embedded in motor windings. It operates on a 24 V AC/DC rated supply and provides a single-pole output rated 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V. The relay features auto-reset (no external reset input) and a standard evaluation unit suitable for bimetallic switches. The IP20 housing protects against finger contact but requires enclosure for washdown or dust environments.
The 24 V rated supply (both AC and DC, 50/60 Hz) means the relay coil is powered from a common 24 V control bus. The output contact ratings — 1 A at 24 V, 0.2 A at 125 V, 0.1 A at 250 V — define the maximum switching capacity for the alarm or trip signal; for motor control circuits, this typically drives a contactor coil or PLC input, not the motor directly. Auto-reset means the relay automatically returns to normal state when the motor cools and the PTC resistance drops below the reset threshold (initial value 0.85, full-scale 1.1). No external reset button or remote reset signal is required, which simplifies wiring but means the motor restarts automatically after a thermal trip — verify this is acceptable for your safety scheme. The relay is designed for bimetallic switch PTC sensors (standard evaluation unit). It provides galvanic isolation between input and output and between outputs, with a relative metering precision of 9 %.
Clearance distances: 0 mm upwards, forwards, backwards, downwards, and at the side — meaning it can be mounted flush against other devices without additional spacing for cooling or arc flash. Terminals accept solid or stranded wire: 1x 20–12 AWG solid, 2x 20–14 AWG solid; stranded 20–12 AWG. Depth is 90 mm, height 100 mm, width 22.5 mm — fits standard 22.5 mm modular enclosure footprint.