The Siemens SIRIUS 3RH2911-2XA40-0MA0 is an auxiliary switch block with four instantaneous normally-open contacts, designed to snap onto the front of SIRIUS contactors in sizes S00, S0, S2, and S3. It carries a 6 A rating at 24 V and a 10 A rated value at 24 V, with the contact reliability specified at one faulty switching per 100 million operations at 17 V, 1 mA — a figure that matters for PLC-level signal circuits where a single missed pick-up can fault a safety chain.
The switching capacity drops with voltage: 6 A at 24 V and 230 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V and 250 V, and 3 A at 400 V. The rated values (thermal current) are higher: 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V. The 6 kV surge voltage resistance means the contacts can handle transient spikes common in motor starter panels without welding shut.
Snap-on mounting to the front of the contactor — no tools, no DIN-rail space consumed beyond the contactor itself. The block measures 36 mm wide, 47.7 mm deep, and 41.5 mm high, fitting within the contactor envelope. Wiring accepts 2x (0.5 to 2.5 mm²) solid or stranded, or 2x (20 to 14 AWG). IP20 on the front side; fine for enclosed panels but not for washdown environments.