The Siemens SIRIUS 3RH1911-1FA20-ZW95 is an auxiliary switch block that adds 2 normally open (NO) contacts to a size S00 contactor or contactor relay. It snaps onto the front of the device — no tools, no extra DIN-rail space — and terminates via screw-type terminals accepting 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) per clamp. The contact block is rated for a maximum of 10 A, with specific current ratings that vary by voltage and duty cycle. Because this is an auxiliary switch block, the ratings that matter are the contact currents at the voltage you are switching — not a motor-load rating. At 24 V it handles 6 A; at 125 V it handles 6 A; at 230 V it handles 6 A; at 400 V it derates to 3 A. For DC control circuits, the 24 V rated value is 10 A, dropping to 0.26 A at 600 V. The 6 kV surge voltage resistance and 690 V insulation voltage (pollution degree 3) mean it holds up in industrial panels without extra clearance. Mechanical life is rated at 10 million switching cycles typical, and contact reliability is specified at 1 faulty switching per 100 million operations at 17 V and 1 mA — useful for PLC-level signals where dry-circuit reliability matters. The operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C.
Integration into existing panels
The 3RH1911-1FA20-ZW95 snaps onto any SIRIUS size S00 contactor or contactor relay (3RT2, 3RH2 base devices). It occupies no additional DIN-rail width — the block sits on the contactor's front face. Dimensions are 36.5 mm wide, 37.5 mm high, and 41.5 mm deep from the contactor face. The IP20 front protection means it is safe for finger-probe access inside an enclosed panel but not for washdown environments.