What it is and what it does
The Siemens SIRIUS 3RH1911-2FA31-ZW98 is an auxiliary switch block that adds 3 normally-open and 1 normally-closed instantaneous contacts to SIRIUS contactor relays and power contactors in size S00. It snaps onto the contactor via the standard DIN-rail mounting method, occupying a 36.5 mm width and 46 mm depth on the rail. Spring-loaded terminals accept 2x (0.5... 1.5 mm²) with ferrules or 2x (0.5... 2.5 mm²) solid, or 2x (20... 14) AWG — no screwdriver torque needed, which speeds panel wiring.
Switching ratings and what they mean for your circuit
The contacts carry a maximum of 10 A, but the real-world rating depends on the voltage and load type. At 24 V the rated operational current is 10 A; at 230 V AC it's 6 A; at 400 V it drops to 3 A. For DC switching, the 24 V DC rating is 6 A, and at 110 V DC it's 1 A — the arc extinction limits current as voltage rises. Insulation voltage is 690 V at pollution degree 3, with a surge voltage resistance of 6 kV, so it's suitable for 400 V line-to-line control panels with decent clearance. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — a dry-circuit spec that matters for PLC input signals where low-level switching is required.
Lifecycle and sourcing reality
Multi-unit packaging of 60 pieces is the standard delivery unit for this variant. For a BOM freeze or last-time-buy situation, sourcing this exact code is quoted to order against an RFQ. If your design is still in development, the 3RH2 successor should be evaluated for drop-in compatibility.
Where it fits in the panel
Snap-on mounting onto 35 mm DIN rail per EN 50022, size S00 footprint — the block adds 36.5 mm to the contactor width and 46 mm depth from the rail. IP20 protection on the front means it's protected against finger contact but not washdown — standard for enclosed control panels. Operating temperature range of -25 to +60 °C covers most indoor industrial environments; storage range extends to -55 to +80 °C. Mechanical service life is 10 million switching cycles typical, which matches the base contactor's auxiliary block endurance.