What it is and what it fits
The Siemens SIRIUS 3RH1911-1NF11 is a solid-state compatible auxiliary switch block with 1 normally open and 1 normally closed instantaneous contact, designed for use with SIRIUS contactor relays and power contactors in the size S00 frame. It snaps onto a 35 mm DIN rail per EN 50022 and occupies a 36.5 mm wide slot — the S00 footprint that fits alongside the base contactor without eating extra panel width. Rated insulation voltage is 690 V at pollution degree 3, with a surge voltage resistance of 6 kV, so it holds up in industrial panels where transient spikes are common.
Key ratings and what they mean for fit
The contacts are rated for 0.3 A at both 24 V and 60 V — this is a signal-level auxiliary switch, not a power contactor. It handles PLC inputs, relay coils, and indicator lamps, not motor currents. Contact reliability is specified as 1 faulty switching per 100 million operations at 17 V, 1 mA. That low-level switching guarantee means it works with solid-state inputs and dry-contact circuits where oxide films on standard contacts would cause intermittent faults. Mechanical service life is 5 million operating cycles typical — adequate for most auxiliary switching duties in a control panel, though a high-cycle pick-and-place line might want to budget for replacement sooner.
Mounting and wiring
Snap-on mounting to 35 mm DIN rail. The 41.5 mm depth keeps it clear of most gland-plate obstructions in a standard 200 mm deep enclosure. Screw-type terminals accept 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²) with core-end processing, or 2x (20... 16) and 2x (18... 14) AWG. Strip and torque per Siemens standard — no special tooling needed. IP20 on the front means it's protected against finger contact but not washdown; keep it inside a closed panel.