What it is and what it does
The Siemens SIRIUS 3RH1911-1MA11 is an auxiliary switch block that snaps onto S00-size contactors and contactor relays, adding one normally-open and one normally-closed contact. It uses screw-type terminals and is rated for a maximum of 10 A, with specific switching capacities at different voltages — for example, 6 A at 24 V, 3 A at 400 V, and 0.26 A at 600 V. The mechanical service life is rated at 10,000,000 switching cycles typical, with contact reliability of 1 faulty switching per 100 million operations at 17 V, 1 mA.
Panel integration
Snap-on mounting onto the contactor or contactor relay — no DIN rail footprint of its own. The block measures 36.5 mm wide, 41.5 mm deep, and 37.5 mm high. Front protection is IP20, so it's suited for enclosed panel use where no washdown or dust ingress is expected. Wiring is via screw terminals accepting 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²) with core-end processing.
What the ratings mean for fit
The 10 A maximum is the thermal current (Ith) — the continuous current the contacts can carry in free air. The real switching capacity depends on voltage and load type: at 24 V it switches 6 A, at 110 V it drops to 1 A, and at 600 V it's only 0.26 A. For AC-15 inductive loads (typical for contactor coils and solenoid valves), the rated value at 690 V is 1 A. The surge voltage resistance is 6 kV, and insulation voltage is 690 V at pollution degree 3.