The Siemens 3RN2010-1CW30 is a SIRIUS 3RN2 thermistor motor protection relay — a compact evaluation unit that works with PTC thermistor sensors embedded in motor windings. It's designed to trip when the motor exceeds safe temperature, protecting against overload or cooling failure. The supply is rated 24-240 V AC/DC (50/60 Hz), so it fits both standard control voltages without needing a separate power supply. Output contacts are rated 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V — these are dry switching levels for signaling to a PLC or contactor coil, not for direct motor loads. The unit auto-resets after the fault clears, which keeps a line restart automatic unless you wire the reset externally. There's no error memory, so a momentary power loss clears the trip state. It snaps onto 35 mm DIN rail (screw and snap-on) and measures 17.5 mm wide × 100 mm high × 90 mm deep — one standard module width.
Wiring & Mounting Notes
Terminals accept solid wire 20-12 AWG (1x or 2x 20-14 AWG for solid) and stranded 20-12 AWG. No clearance needed above, below, or to the sides (0 mm each direction), so you can pack modules tight on the rail. The LED display gives a quick visual on trip status without a multimeter.