What it is and where it fits
The Siemens 3RH2911-1HA10-ZW97 is a front-mounted auxiliary switch block for the SIRIUS 3RT2 contactor and 3RH2 contactor relay family. It adds one normally-open (1 NO) instantaneous contact to the front of the device, wired via screw-type terminals. The "with 3RH2" note on the order code flags that this variant is specifically packaged and kitted for the 3RH2 contactor relay line — same electrical stack, different logistics bundle. Snap-on mounting to the contactor front face — no tools, no panel mods. The IP20 front protection means it's safe for finger contact inside an enclosed panel but not for washdown areas.
Contact ratings — what the numbers mean for your circuit
The single NO contact is rated for a maximum of 10 A, but that's the thermal current — the real switching capacity depends on voltage and load type. At 24 V it handles 6 A; at 230 V it also carries 6 A, but at 400 V it drops to 3 A, and at 690 V in AC-15 duty (solenoid/contactor coil loads) it's rated 1 A. The AC-15 rating at 690 V is the one to watch if you're switching inductive loads at higher voltages — that 1 A figure governs the coil count you can drive. DC switching follows a different derating curve: 10 A at 24 V DC, 4.7 A at 60 V, 3 A at 110 V, dropping to 0.26 A at 600 V DC. For DC control circuits, the voltage-specific rating is the binding constraint — don't size by the 10 A thermal number alone. Contact reliability is spec'd at 1 faulty switching per 100 million operations at 17 V, 1 mA — that's the dry-circuit performance for PLC-level signals. Mechanical life is 10 million switching cycles typical, so this block will outlast most contactors it rides on.
Termination and wiring
Screw-type terminals accept 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 solid/stranded. The 43.7 mm depth, 36 mm width, and 37.5 mm height keep it within the contactor envelope — no extra DIN-rail space consumed. Surge voltage resistance is rated at 6 kV, and insulation voltage at 690 V AC with pollution degree 3 — suitable for industrial control panels where transient overvoltages are common.