Siemens SIRIUS 3RH1911-1FB11 — Auxiliary Switch Block, Phased Out
The Siemens SIRIUS 3RH1911-1FB11 is an auxiliary switch block with one normally-open and one normally-closed contact, rated for 10 A maximum and designed for use with SIRIUS contactor relays and power contactors in the S00 frame size. It snaps onto DIN rail and accepts screw-type terminals for auxiliary and control circuits, with wire sizes from 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core end processing, or 2x (20 to 16) and 2x (18 to 14) AWG.
Switching Ratings — What They Mean for Your Circuit
The 10 A maximum rating applies at 24 V; at higher voltages the current capacity drops — 6 A at 230/250 V, 3 A at 400 V, and 0.26 A at 600 V. For DC switching, the block handles 6 A at 24 V, 2 A at 60 V, and 0.3 A at 220 V. These curves mean the block is best suited for control circuits at typical panel voltages (24 VDC or 230 VAC), not for high-current power paths. The AC-15 rating at 690 V is 1 A, confirming its role in switching solenoid and contactor coils — the standard duty for auxiliary contacts in motor control centers. Contact reliability is specified as one faulty switching per 100 million operations at 17 V, 1 mA, which is typical for dry-circuit signal integrity in PLC input circuits. Mechanical service life is rated at 10 million switching cycles.
Lifecycle Reality — Phased Out, Successor Available
The 3RH1911-1FB11 is a phased-out product. The manufacturer lists the SIRIUS 3RH2911-1FB11 as the preferred successor type. For new designs or BOM replacements, that is the direct drop-in to specify.
Panel Integration — Snap-On Mounting, S00 Frame
The block snaps onto DIN rail (snap-on mounting per) and fits the S00 contactor frame size. Dimensions are 36.5 mm wide, 41.5 mm deep, and 37.5 mm high — it occupies the same footprint as the SIRIUS 3RH2 series auxiliary blocks. The leading contact closes before the main contactor poles, and the lagging contact opens after — a standard arrangement for NC mirror contacts in safety circuits. There is no instantaneous contact (0 per). Front-side protection is IP20, suitable for enclosed panel installation. Insulation voltage is 690 V AC at pollution degree 3, with a surge voltage resistance of 6 kV.