What it is and what it does
The Siemens 3RT1036-3BW40 is a SIRIUS power contactor in size S2, designed for switching motor loads and resistive loads in industrial control panels. It mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022, which means it integrates directly into a standard panel layout without adapter plates. The key motor-switching rating is 41 A at AC-4 duty at 400 V, which covers severe inching, plugging, and reversing applications where the contactor must interrupt locked-rotor currents. For less demanding AC-2 duty at 400 V, it handles 22 kW, typical for slip-ring motor starting.
Terminals and wiring
Main current circuit connections use screw-type terminals. The main circuit accepts stranded wire up to 2x 25 mm² or solid up to 2x 2.5 mm², with a minimum permissible cross-section of 16 mm² at 40 °C. This gives you headroom for the full rated current without derating the terminal block. The front of the contactor carries IP20 protection, so accidental finger contact with live terminals during panel access is guarded against. The terminal area itself is IP00, which is normal for enclosed panel installations.
Lifecycle and sourcing
RoHS compliance is confirmed with a substance prohibition date of 05/01/2012, covering the EU RoHS directive. The operating temperature range is -25 to +60 °C, with storage down to -55 °C, which suits most industrial environments including unheated warehouses.
Switching performance and coil data
The contactor's mechanical life is rated at 10,000,000 typical operations, which is the figure to use for maintenance planning in high-cycle applications like conveyor sortation or packaging lines. Electrical life varies by duty: maximum 1,000 operations per hour at AC-1, 800 at AC-3, and 300 at AC-4. Arcing time is 10 to 15 ms, and the DC dropout time is 20 to 25 ms. These matter when coordinating contactors in a reversing starter or when sequencing multiple contactors to avoid short circuits between phases.