SIRIUS S2 power contactor, 24 VDC coil
The Siemens 3RT1036-3BB44-3MA0 is a SIRIUS power contactor in size S2, rated for a 24 VDC coil with screw-type terminals on the main current circuit. The front face carries an IP20 rating, while the terminal area is IP00 — standard for panel-mount contactors where the enclosure provides the final ingress protection. Mechanical life is rated at 10,000,000 operations typical, and the contactor supports side-by-side mounting on 35 mm DIN rail per EN 50022, with both screw and snap-on fastening. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C, and pollution degree 3 suits industrial environments with conductive contamination.
Switching ratings and duty cycles
The AC-3 motor-switching rating at 400 V is 22 kW, corresponding to a 41 A make/break capability in AC-4 duty at the same voltage. For resistive loads (AC-1), the contactor can cycle at up to 1000 operations per hour; AC-3 duty maxes at 800 ops/h, AC-4 at 300 ops/h. These figures define the thermal and mechanical limits for repetitive starting and inching applications. DC switching ratings are provided per voltage step: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. The arcing time is 10 to 15 ms, with a DC-specific arcing time of 20 to 25 ms — relevant when sizing suppression networks for inductive DC loads.
Mounting and wiring
The contactor occupies a 55 mm wide footprint on a 35 mm DIN rail (EN 50022). Screw terminals accept solid conductors 2x (0.25 to 2.5 mm²) and stranded conductors 2x (0.75 to 25 mm²) on the main circuit. The minimum permissible cross-section at 40 °C is 16 mm² for the main circuit — ensure the panel wiring matches this for full rated current. Side-by-side mounting is permitted without derating, which simplifies dense panel layouts. The S2 frame size is a common Siemens platform, so auxiliary contact blocks and surge suppressors from the SIRIUS family fit without adapters.