What this auxiliary switch does in a panel
The 3RH2911-4FB11 is a SIRIUS auxiliary switch block designed to snap onto the front of Siemens contactor relays and power contactors in frame sizes S00, S0, S2, and S3 — it adds one normally-open and one normally-closed auxiliary contact to the base device without extra wiring or panel space. Mounting is tool-free: the block snaps onto the contactor front face, and the connection uses ring terminal lugs — no push-in or screw-cage terminals, so factor in a crimp tool and ring terminals for the control wiring. The auxiliary contacts are rated for a mechanical service life of 10 million operating cycles typical, with a contact reliability of one faulty switching per 100 million operations at 17 V, 1 mA — that low-level spec matters for PLC inputs that sink milliamps through dry contacts.
Switching ratings — what the numbers mean
The contact block carries a maximum operational current of 10 A at AC-12 (resistive loads), but the actual switching capacity depends on the voltage and duty: at 24 V it switches 6 A (AC-15) or 10 A (rated value), while at 230 V it handles 6 A AC-15 and at 400 V it switches 3 A — the voltage derating is steep above 230 V. For inductive loads in AC-15 duty at 690 V, the rated operational current is 1 A — this is the figure to use for contactor coil feedback or valve solenoids on a 690 V line. The DC switching capability covers 24 V at 10 A, 60 V at 4.7 A, 110 V at 3 A, 220 V at 1.2 A, and 600 V at 0.26 A — the rapid derating above 110 V means this block is best suited for 24 VDC control circuits unless the load is very light. Surge voltage resistance is rated at 6 kV, which covers most industrial control panel transient environments without additional snubbers.
Lifecycle and sourcing reality
The IP00 front protection rating means this block is intended for installation inside a closed panel — not for washdown or outdoor exposed mounting without an additional enclosure. RoHS compliance is documented with a substance prohibition date of October 1, 2009; the part does not carry mirror contact functionality per IEC 60947-4-1, so it is not suitable for applications requiring mirrored auxiliary contacts for safety feedback.
Panel fit — dimensions and integration
The block measures 36 mm wide, 37.5 mm high, and 43.7 mm deep — it adds negligible depth to the contactor stack and fits within the standard S00/S0/S2/S3 footprint without encroaching on adjacent devices. Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C — adequate for most indoor industrial environments but verify ambient near ovens or foundry lines.