The Siemens SIRIUS 3RH1911-1GA31-ZW97 is an auxiliary switch block with three normally-open instantaneous contacts, designed for snap-on mounting onto the front of S00-size contactors and contactor relays. It carries a rated operational current of 6 A at 24 V and 230 V in AC-15 duty, and 10 A at 24 V in AC-12 duty — the AC-15 figure governs the inductive load switching (solenoids, contactor coils), while AC-12 covers resistive loads. The switch is rated for a surge voltage resistance of 6 kV and meets mirror contact requirements per IEC 60947-4-1 when used with a 3RT1 contactor, meaning it provides a positively driven N/C contact that signals the state of the main poles — critical for safety circuits that need to detect welding or stuck contacts.
Ratings and what they mean for fit
The AC-15 current ratings drop as voltage rises: 6 A at 230 V, 3 A at 400 V, 1 A at 690 V. That 1 A at 690 V is the limiting case for a 690 V panel — if your control circuit runs at that voltage, the switch handles up to 1 A inductive. The AC-12 maximum of 10 A at 24 V is the resistive limit; don't plan on switching a 10 A solenoid at 24 V, because the inductive inrush will exceed the AC-15 rating. The mechanical service life of 10 million operating cycles is typical for a SIRIUS block — it will outlast the contactor in most cyclic applications.
Mounting and wiring
Snap-on mounting to the front of the contactor or contactor relay — no tools needed. The block is sized for S00 frames (3RT2, 3RT1). It accepts 2 x (0.5 to 1.5 mm²) solid or stranded, or 2 x (0.75 to 2.5 mm²) with ferrules; AWG equivalents are 2 x (20 to 16) and 2 x (18 to 14). The front protection class is IP20, so it's fine inside a closed panel but not for washdown areas. The product design also allows snapping onto the front of a 3RH2140 or 3RH2440 auxiliary switch block for stacking additional contacts.