What It Is and Where It Fits
The Siemens SIRIUS 3RH1911-1FA40-ZW97 is an auxiliary switch block designed to snap onto the front of S00-size contactor relays and power contactors. It adds four normally-open instantaneous contacts for signal feedback or interlocking in motor control circuits. Rated for 10 A at 24 V for AC-12 duty, it handles control-circuit switching across a range of voltages — 6 A at 24 V, 2 A at 48 V, 1 A at 110 V, and 0.3 A at 250 V — so the same block works from 24 VDC control loops up to 250 VAC pilot circuits. The surge voltage resistance is rated at 6 kV, and the contacts are mirror contacts per IEC 60947-4-1 when used with the 3RT1 contactor series, meaning a welded contact won't go undetected in safety circuits.
Mounting and Panel Fit
Snaps directly onto the front of an S00 contactor — no tools, no DIN rail space consumed. The block measures 36.5 mm wide by 41.5 mm deep by 37.5 mm tall, so it adds minimal depth to the contactor assembly inside the panel. Terminals accept 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) stranded, or 2x (20 to 16) AWG. Finely stranded with ferrules is the same range. Strip length follows standard practice for spring-cage terminals. Front protection class is IP20, so it's fine inside a closed panel but not for washdown or outdoor exposure.
Lifecycle and Sourcing Reality
RoHS compliance is confirmed with a substance prohibition date of July 1, 2006. The mechanical service life is rated at 10 million operating cycles typical, and contact reliability is 1 fault per 100 million operations at 17 V, 1 mA.