The Siemens SIRIUS 3RH2911-4FC22 is a front-mounted auxiliary switch block for 3RT2 power contactors and 3RH2 contactor relays. It provides 2 normally open and 2 normally closed auxiliary contacts arranged as 1 NO leading, 1 NO leading, 1 NC lagging, 1 NC lagging — a 22 U contact configuration that gives you sequenced make/break timing for control logic. Snap-on mounting onto the contactor front means no tools needed for installation or replacement; the block clips directly onto the contactor's front face. The 36 mm width and 43.7 mm depth keep it within the contactor's own footprint.
The contacts are rated for 10 A maximum, but that's the thermal current — the actual switching capacity depends on the voltage and duty. At 24 V DC the contacts handle 6 A; at 60 V DC it drops to 2 A; at 110 V DC it's 1 A; at 220 V DC it's 0.3 A. For AC-15 inductive loads at 690 V the rating is 1 A. These are the numbers that govern whether this switch survives in your specific control circuit. Mechanical life is 10 million switching cycles typical.
Connection and environment
Termination is via ring cable lugs — not screw terminals or spring cages. That means you need a ring terminal crimped onto each wire, then bolted to the contact post. Factor that into your panel wiring plan if you're used to push-in or screw-clamp aux blocks. Protection class on the front is IP00 — it relies on the panel enclosure for environmental sealing.