The Siemens SIRIUS 3RH1911-1HA22-ZW97 is a 4-pole auxiliary switch block with 2 normally open and 2 normally closed contacts, rated for a maximum of 10 A and designed for snap-on mounting onto SIRIUS contactor relays and power contactors. This is the variant with the ZW97 modifier — a multi-unit packaging configuration (140 units per pack) that signals bulk procurement, not a standard single-unit order code.
What the ratings mean for fit
The 10 A maximum is the thermal continuous current (Ith) — the block can carry 10 A through any closed contact indefinitely at rated temperature. But switching capacity depends on voltage and duty: at 24 V it switches 6 A (AC-15, typical for solenoid loads), at 110 V it drops to 1 A, and at 400 V it handles 3 A. The AC-15 rating at 690 V is 1 A — that's the inductive load capability at the insulation voltage ceiling. For DC switching, the 24 V rated value is 10 A, but at 220 V it falls to 1.2 A, and at 600 V to just 0.26 A. The buyer selecting this for a 24 VDC control circuit gets the full 10 A; for a 230 VAC pilot circuit, expect 6 A. The insulation system is rated 690 V AC with pollution degree 3 (typical for industrial control panels where conductive dust or humidity is present), and surge voltage resistance is 6 kV. That means it can be used in 400 V motor starter circuits without additional isolation, as long as the contactor it mounts on shares the same pollution environment. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — this is the dry-circuit reliability figure. For low-energy signal switching (PLC inputs, sensor signals), the contacts are rated for gold-level reliability, not just power switching. Mechanical life is 10 million switching cycles typical.
Mounting and wiring
Snap-on mounting directly onto SIRIUS contactor relays and power contactors — no DIN rail required. The block clips onto the front of the contactor, adding auxiliary contacts without increasing panel width. Dimensions are compact: 36.5 mm wide, 41.5 mm deep, 37.5 mm high, fitting within the contactor envelope for size S00 and S0 frames. 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) or 2x (18 to 14 AWG) for solid/stranded. The IP20 front protection means the terminals are finger-safe but the block is not sealed — install inside a cabinet rated for the environment.