What this auxiliary switch block is and where it fits
The Siemens 3RH2911-2HA22-ZX95 is a front-mounted auxiliary switch block for the SIRIUS family, designed to snap onto 3RT2 power contactors and 3RH2 contactor relays. It provides 2 normally-open and 2 normally-closed instantaneous contacts, wired via spring-loaded terminals that accept 2x (0.5 to 2.5 mm²) stranded or solid wire without ferrules. Rated at 10 A at 24 V and carrying an AC-15 rating of 1 A at 690 V, this block handles typical control-circuit loads — solenoids, contactor coils, pilot lights — inside a panel. The 6 kV surge voltage resistance and insulation voltage of 690 V at pollution degree 3 keep it reliable in industrial environments where transient spikes are common.
Contact configuration and switching capacity across voltages
The four contacts are arranged as two NC and two NO paths. The manufacturer specifies the rated current at multiple voltage levels for DC switching: 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 6 A at 250 V, 3 A at 400 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. An additional set of rated values at 24 V (10 A), 60 V (4.7 A), 110 V (3 A), 220 V (1.2 A), 440 V (0.5 A), and 600 V (0.26 A) covers the full DC load range. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — a dry-circuit rating that matters when switching low-energy signals like PLC inputs. Mechanical life is 10 million switching cycles typical.
Snap-on mounting and panel integration
Snap-on mounting directly onto the contactor or relay body — no tools, no DIN-rail footprint consumed. The block measures 36 mm wide, 47.7 mm deep, and 41.5 mm high. Spring-loaded terminals accept 2x (0.5 to 1.5 mm²) with ferrules or 2x (0.5 to 2.5 mm²) without, plus 2x AWG 20 to 14 for auxiliary circuits. IP20 on the front face means it's protected against finger contact but not washdown — standard for enclosed panel use.