Auxiliary contactor for SIRIUS S00 contactor systems
The Siemens 3RH1140-2BA40 is a SIRIUS auxiliary contactor in Size S00, designed to add signal or control contacts to a motor starter or contactor assembly. It carries 4 normally-open instantaneous contacts rated 10 A in AC-12 duty (resistive loads at 24 V to 690 V). The 12 V DC coil draws a constant 3.2 W for closing and holding, which simplifies the power supply budget in a 24 V DC control bus—no inrush to size a transformer for. Mounting is via screw or snap-on onto a DIN rail, with a 45 mm width that fits standard S00 contactor spacing. The IP20 front protection means it is suitable for enclosed panel use only—no washdown or outdoor exposure without an additional enclosure.
Key ratings and what they mean for fit
The 10 A AC-12 rating at 690 V covers resistive switching for pilot lights, PLC inputs, and small solenoid valves. For inductive loads like contactor coils or small motors, derate to the AC-15 values: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. The 6 kV surge voltage resistance (per IEC 60947-1) ensures the contacts withstand switching transients on a 400 V line without flashover. The 12 V DC coil is the less common variant—most SIRIUS aux contactors are 24 V DC or 110-240 V AC. Verify your control voltage matches exactly; a 24 V coil on a 12 V bus will not pull in reliably. Coil holding power is 3.2 W DC, so a 24 V DC supply with 0.13 A per contactor is sufficient. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 (conductive pollution) means it is rated for industrial environments where occasional condensation or light dust is present. Shock resistance of 10g at 5 ms and 5g at 10 ms covers most panel vibration from contactors and pumps. Mechanical endurance is 30 million cycles typical—this is the life of the contactor mechanism, not the electrical contact life under load. For high-cycle applications (e.g., PLC-driven valve banks), the electrical life at rated AC-15 current will be lower; plan spares accordingly.
Integration and wiring notes
The 3RH1140-2BA40 snaps onto the left or right side of a SIRIUS S00 contactor (e.g., 3RT1015 or 3RT1016) using the integrated slide-in mechanism. No additional hardware is needed. The 45 mm width matches the contactor footprint, so a 2-wide assembly (contactor + aux block) occupies 90 mm of DIN rail. Terminals accept 2x (0.25 to 2.5 mm²) solid or stranded wire. For 10 A circuits, 1.5 mm² is adequate; for long runs or daisy-chaining multiple aux contacts, use 2.5 mm² to keep voltage drop under 3%. Depth is 73 mm, height 60 mm—allow 80 mm clearance in front for wiring access. Mounting position is flexible: it can be rotated ±180° on a vertical surface and tilted ±22.5° forward/backward. This helps in tight enclosures where the DIN rail is not perfectly horizontal.
Lifecycle and sourcing posture
For a BOM freeze or panel production run, this part is a safe choice—no imminent obsolescence risk. If you are replacing an older SIRIUS 3RH1 block from the 1990s, verify the coil voltage; the mechanical interface is unchanged.