SIRIUS S2 power contactor – 3RT1035-1BM44
The Siemens 3RT1035-1BM44 is a SIRIUS power contactor in size S2, rated for motor switching up to 35 A in AC-4 duty at 400 V and 22 kW at 500 V. It uses screw-type terminals for the main circuit and mounts on a 35 mm DIN rail per EN 50022, with side-by-side mounting permitted. The front face carries IP20 protection; the terminal area is IP00 — expect that in a panel environment where the enclosure provides the overall ingress rating.
What the ratings mean for fit
The AC-4 rating of 35 A at 400 V is the heavy-duty plugging / inching category — frequent starts, reversals, or jogging. If your application cycles the contactor under load more than a few times per hour, AC-4 is the limiting curve, not the higher AC-3 figure. The 22 kW at 500 V gives the motor power capacity for a typical 500 V three-phase induction motor. Coil pickup and dropout times are 20–25 ms DC; arcing time is 10–15 ms — fast enough for most safety circuits but verify coordination with upstream protection if you need arc-fault clearing under 10 ms.
Panel integration notes
Width is 55 mm, height 112 mm, depth 179 mm — fits a standard S2 contactor footprint on 35 mm DIN rail. Screw terminals accept solid conductors up to 2x 4 mm² (or 2x 1.5 mm²) and stranded up to 2x 25 mm². Pollution degree 3 means it's rated for industrial environments with conductive pollution; no additional conformal coating is required for most panel conditions. Storage temperature range is -55 to +80 °C, operating -25 to +60 °C.