The Siemens 3RH2911-2HA01-ZX95 is a SIRIUS auxiliary switch block that mounts on the front of 3RT2 contactors and 3RH2 contactor relays, adding one normally-closed (NC) contact path. It uses spring-loaded terminals — no screwdriver needed for the control wiring, which speeds up panel assembly and stays tight under vibration on a conveyor line or pump panel.
Ratings and what they mean for fit
Rated 10 A at 24 V for general-purpose use, but the AC-15 rating at 690 V is 1 A — that's the figure that governs switching solenoids and contactor coils in a 480 V panel. The 6 kV surge voltage resistance (rated impulse withstand) means it coordinates with standard industrial control transformers and doesn't need extra suppression for most PLC outputs. Contact reliability is spec'd at 1 faulty switching per 100 million operations at 17 V, 1 mA — that's dry-circuit capability, so it handles low-level signals from a sensor or PLC input without needing a separate interface relay. Mechanical life is 10 million cycles typical; the spring terminals don't wear out from repeated wiring changes during commissioning. Rated insulation voltage is 690 V at pollution degree 3, which covers most industrial environments where conductive dust or humidity is present. The IP20 front protection means it's safe for finger contact inside an enclosed panel — not for washdown areas.
Mounting and wiring
Snap-on mounting to the contactor front — no tools, no DIN rail. The block adds 36 mm width and 47.7 mm depth to the assembly; check your enclosure depth if the contactor is already tight against the gland plate. Wire capacity is 2x 0.5–2.5 mm² without ferrules, or 2x 0.5–1.5 mm² with ferrules; AWG 20–14 for the US installs. Strip length is the standard 8–10 mm for spring-cage terminals.