What it is and what it fits
The Siemens SIRIUS 3RH2911-2HA22-ZW96 is a front-mounted auxiliary switch block designed specifically for the 3RT2 power contactor and 3RH2 contactor relay families. It provides 2 normally-open and 2 normally-closed contacts, wired out to spring-loaded terminals that accept 2x (0.5... 1.5 mm²) with ferrule or 2x (0.5... 2.5 mm²) solid — no screw torque to check, no loosening from vibration. The snap-on mounting clips directly to the contactor front, adding no DIN-rail width.
What the ratings mean for the panel
The insulation voltage is rated 690 V at pollution degree 3, so this switch block can live in the same panel as the main power contactor without forced separation. Surge voltage resistance of 6 kV gives it headroom for the transient spikes common in motor circuits — no up-tower swaps on a wind turbine if a surge hits. The AC-15 rating at 690 V is 1 A, meaning it can reliably switch solenoid valves and contactor coils at line voltage in industrial control circuits. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — that covers PLC-level dry circuits, so it handles both power and signal loads without a separate interface relay.