The Siemens SIRIUS 3RH1911-2GA04 is a 4-pole auxiliary switch block with a 44E contact configuration — 4 normally closed contacts — laid out per EN 50011. It snaps onto a contactor relay or power contactor in the SIRIUS family, extending the auxiliary contact set without extra wiring space. The spring-loaded terminals accept 2x (0.5 to 2.5 mm²) stranded without ferrules, or 2x (0.5 to 1.5 mm²) with core-end processing, matching the standard panel-building practice for control circuits. The 46 mm depth and 36.5 mm width keep the block within the footprint of the base contactor, so it does not push the DIN-rail layout wider.
The block carries a maximum thermal current of 10 A, but the real-world switching capacity depends on voltage and load type. At 24 V it handles 6 A (AC-15) or 10 A (resistive); at 230 V the AC-15 rating drops to 6 A, and at 400 V it is 3 A. For DC switching the numbers tighten further — 0.3 A at 220 V DC, 0.26 A at 600 V DC. These are the values that govern whether the block closes the cycle on a solenoid valve or a small contactor coil. Mechanical service life is rated at 10 million operating cycles typical, and contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — relevant for low-energy PLC inputs where contact oxidation can cause intermittent faults.
Snap-on mounting onto a SIRIUS contactor relay or power contactor. The block shares the same DIN-rail clip as the base device — no additional rail space consumed. The 37.5 mm height keeps it below the arc chamber of most contactors in the series.