Solid-state compatible auxiliary switch for SIRIUS contactors
The Siemens 3RH2911-2NL22 is a front-mounted auxiliary switch block for the SIRIUS 3RT2 contactor family, delivering 2 NO + 2 NC instantaneous contacts in a compact 36 mm wide housing that snaps onto contactor sizes S00, S0, S2, and S3. One of the NO contacts is designated solid-state compatible — rated at 0.3 A at 24 V, 48 V, and 60 V — meaning it reliably switches the low-level signals typical of PLC inputs and solid-state relays without the contact oxidation or stiction that standard auxiliary contacts can develop at milliampere loads. Contact reliability is specified at one incorrect switching operation per 100 million cycles at 5 V, 1 mA, which confirms the block is engineered for the dry-circuit switching demands of electronic control systems.
Spring-loaded termination and panel fit
All auxiliary and control circuit connections use spring-loaded terminals, accepting 2x (0.5... 2.5 mm²) solid or stranded, or 2x (20... 14 AWG) — no screwdriver torque required, which speeds panel wiring and eliminates periodic re-torquing on vibration-prone machine-tool panels. The block measures 36 mm wide × 41.5 mm high × 47.7 mm deep, and snaps onto the contactor front without additional DIN-rail space — critical when the panel is already dense and every millimeter of rail width is allocated to power components.
Rated insulation voltage is 690 V at pollution degree 3, with a rated surge voltage resistance of 6 kV — figures that align with IEC 60947-5-1 requirements for auxiliary contact blocks used in 400 VAC motor control centers. Mechanical service life is 5 million operating cycles typical, which is the block's own endurance — not the contactor's — so factor this into maintenance intervals if the auxiliary block cycles at a different rate than the main power contacts.