What It Is and Where It Fits
The Siemens SIRIUS 3RT1036-3BP40 is a size S2 power contactor designed for switching motor loads and resistive circuits in industrial control panels. It mounts via screw and snap-on onto a 35 mm DIN rail per EN 50022, so it integrates directly into a standard panel layout without a separate base plate. Rated for AC-3 duty at 30 kW on 500 V and 11.4 kW on 690 V, this contactor handles the common motor voltage ranges in European and export panels. The 230 V AC coil (rated value 230 V) is a standard control voltage for many industrial zones.
Key Ratings and What They Mean for Fit
The AC-3 rating (30 kW at 500 V) is the motor-switching current you size against — it covers the majority of three-phase induction motors up to that load. The AC-4 rating (41 A at 400 V) matters for reversing or inching duty where the contactor makes and breaks under full load; the 300 operations per hour maximum in AC-4 reflects the thermal stress of that cycle. For DC switching, the contactor is rated at 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. These are the make/break currents for DC loads — a critical check if you're switching solenoids or DC brake coils, because DC arcs are harder to extinguish than AC. Mechanical life is rated at 10,000,000 operations typical, which is the life of the mechanism before wear-out. The electrical life depends on the switching category — at AC-3 maximum 800 operations per hour, the contactor is rated for high-duty cycling in conveyor or pump applications.
Termination and Wiring
Main current circuit uses screw-type terminals. The main circuit accepts stranded wire up to 2x (0.75... 25 mm²) and solid wire up to 2x (0.25... 2.5 mm²). The auxiliary circuit accepts 2x (0.75... 16 mm²) solid or stranded. The minimum permissible cross-section at 40 °C is 16 mm² — that's the smallest wire you can run at full rated current without exceeding terminal temperature rise. The contactor is rated IP20 on the front (finger-safe) and IP00 at the terminals, so it requires a panel enclosure or additional finger protection at the wiring points. Pollution degree 3 means it's suitable for industrial environments with conductive pollution.