What it is and where it fits
The Siemens 3RH1911-1FA11-ZW98 is a SIRIUS auxiliary switch block designed for the S00 contactor frame size. It snaps onto the front of a contactor relay or power contactor, adding one normally-open instantaneous contact to the assembly. This is the part you add when the base contactor runs out of auxiliary contacts for your feedback or interlock logic.
Switching capacity — what the ratings mean
This auxiliary switch carries two sets of rated values. The first set (at 24 V: 6 A, at 48 V: 2 A, at 60 V: 2 A, at 110 V: 1 A, at 125 V: 0.9 A, at 220 V: 0.3 A, at 230 V: 6 A, at 250 V: 0.3 A, at 400 V: 3 A) reflects the thermal current and switching capability across a range of control voltages — the 6 A at 24 V and 230 V are the peaks, with derating as voltage climbs. The second set (at 24 V: 10 A, at 60 V: 4.7 A, at 110 V: 3 A, at 220 V: 1.2 A, at 440 V: 0.5 A, at 600 V: 0.26 A) is the AC-12 / AC-15 rated operational current for switching resistive and inductive loads. The AC-12 maximum is 10 A. For AC-15 at 690 V it's rated 1 A. So for a 24 VDC PLC output driving a contactor coil, this switch handles the load comfortably; for a 400 VAC motor circuit feedback, it's still good for 3 A.
Safety feature — mirror contact
This auxiliary switch is a mirror contact per IEC 60947-4-1 when paired with a 3RT1 contactor. That means the normally-closed mirror contact cannot close if the main contactor's power contacts are welded shut. It's a safety-relevant feature for feedback circuits in machine guarding or drive safety functions — the NC contact gives a positive indication of the main contact state.
Mounting and wiring
Snap-on front mounting onto S00 contactors — no tools needed, clips into the front face. The block measures 36.5 mm wide, 37.5 mm high, 41.5 mm deep. It accepts 2 x (0.5 to 1.5 mm²) solid or stranded, or 2 x (0.75 to 2.5 mm²) with ferrules. For AWG: 2 x (20 to 16) or 2 x (18 to 14). The front is IP20 protected — safe for finger contact inside an enclosure but not for washdown. Operating temperature is -25 to +60 °C; storage from -55 to +80 °C. Surge voltage resistance is 6 kV.
Compliance documentation
RoHS compliance date is July 1, 2006, which means it meets the original EU RoHS directive. The product carries the SIRIUS brand designation and is designed for use with Siemens contactor systems. No specific UL or CSA listing is stated in the evidence, but IEC 60947-4-1 mirror contact compliance is confirmed.