What this part is and where it fits
The Siemens SIRIUS 3RH1911-1FA40-ZW96 is an auxiliary switch block designed for use with contactor relays and power contactors in the S00 frame size. It provides four normally open (4 NO) instantaneous contacts, wired via screw-type terminals, and snaps onto the contactor without tools — a standard panel integration for motor control centers and distribution boards.
Ratings that decide the fit
The block is rated for a maximum continuous current of 10 A, but the real-world switching capacity depends on the voltage and duty. At 24 V DC it handles 6 A; at 110 V DC it drops to 1 A; at 230 V AC it carries 6 A. These are the numbers that govern whether the block can switch a given pilot device or solenoid without welding contacts. The AC-15 rating at 690 V is 1 A — that's the inductive load curve for contactor coils and valves at higher line voltages. Contact reliability is specified at one faulty switching per 100 million operations at 17 V, 1 mA — a dry-circuit capability that matters for PLC inputs and low-energy signal paths. Mechanical life is 10 million switching cycles typical, so the block outlasts most contactors it mounts on. Insulation voltage is 690 V AC at pollution degree 3, with a rated surge voltage resistance of 6 kV. That places it in the standard industrial insulation coordination class for ungrounded or grounded 400 V systems. The front face carries IP20 protection — finger-safe but not sealed; keep it inside the enclosure.
Mechanical fit and wiring
Dimensions are 36.5 mm wide, 37.5 mm high, 41.5 mm deep — compact enough for dense panel layouts on the S00 contactor footprint. Snap-on mounting means no screws for the block itself; the contactor carries it. Wiring accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core-end processing, or 2x (20 to 16 AWG) and 2x (18 to 14 AWG) for stranded cable. Operating temperature range is -25 to +60 °C; storage from -55 to +80 °C.