What it is and what it does
The Siemens 3RH1131-1AF10 is a SIRIUS auxiliary contactor in size S00, designed to switch control circuits — think signal-level loads like PLC inputs, relay coils, and indicator lamps — not motor power. Its three normally-open and one normally-closed instantaneous contacts handle up to 10 A at AC-12 duty (resistive control loads at 24 V), with a surge voltage resistance rated at 6 kV. The 3 NO + 1 NC configuration is a standard pick for extending the auxiliary contact count on a main contactor or for building interlock logic in a panel.
Mounting and integration
Fastens via screw and snap-on mounting onto a DIN rail. The S00 footprint is 45 mm wide, 57.5 mm high, 72 mm deep. Mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward. IP20 front.
Ratings and what they mean for your circuit
The headline 10 A at AC-12 tells you this contactor can switch resistive loads at up to 10 A — that's the rating for control transformers, solenoid valves, and contactor coils. For inductive DC loads the ratings drop significantly: 10 A at 24 V DC, but only 1 A at 110 V DC, 0.27 A at 220 V DC. At 230 V AC (50 Hz) it handles 6 A, and at 400 V AC it's rated 3 A. The contact reliability spec — one incorrect operation per 100 million cycles at 17 V, 1 mA — means it's trustworthy for low-energy PLC input circuits where oxide film on dry contacts can cause intermittent faults. Mechanical life is 30 million operations typical, so it outlasts most panel rebuild cycles.
Wiring and environment
Terminals accept solid conductors from 0.5 mm² up to 4 mm² (or 2x 0.5–1.5 mm² and 2x 0.75–2.5 mm²), with AWG equivalents of 20–16, 18–14, and 12 for the larger single conductor. Operating temperature range is -25 to +60 °C, with storage and transport from -55 to +80 °C. Shock resistance is rated at 10g for 5 ms and 5g for 10 ms — fine for most industrial machinery but worth noting if the panel mounts directly on a vibrating press or conveyor drive. Pollution degree 3 means it's suited for industrial environments with conductive dust or occasional condensation.