Front-Mounted Auxiliary Switch for SIRIUS Contactors
The 3RH2911-1FA40-ZW98: This is a front-mounted auxiliary switch block for the Siemens SIRIUS line, designed to snap onto 3RT2 contactors and 3RH2 contactor relays. It adds 4 normally-open (NO) instantaneous switching contacts to the base device, wired through screw-type terminals. Rated for 10 A maximum, with specific current ratings across AC voltages: 6 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V. For DC control circuits, it handles 10 A at 24 V, 3 A at 110 V, and 0.5 A at 440 V.
What the Ratings Mean for Panel Fit
The 36 mm width and snap-on DIN rail mounting mean it takes up one standard module on the rail — no extra panel space beyond the contactor footprint. The 43.7 mm depth keeps it inside the envelope of most 3RT2/3RH2 assemblies, so it won't crowd the enclosure door or adjacent wiring ducts. Screw terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) conductors — that's 20–16 AWG and 18–14 AWG respectively. The dual-wire entry per clamp is useful for daisy-chaining common signals without a separate terminal block. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V and 1 mA — that's the dry-circuit performance for PLC-level signals. Mechanical life is 10 million switching cycles typical.