What it is and what it does
The Siemens SIRIUS 3RT1044-3BE40 is a size S3 power contactor rated for switching motor loads in industrial control panels. It carries a 55 A AC-4 rating at 400 V, which covers reversing, plugging, and inching duty cycles where the contactor makes and breaks stalled-rotor current. For AC-2 duty (slip-ring motors or wound-rotor applications), it delivers 30 kW at 400 V. The AC-3 rating for standard squirrel-cage motors is 37 kW at 500 V and 18.6 kW at 690 V.
Mounting and integration
Mounts via screw or snap-on onto standard 35 mm or 75 mm DIN rails. Side-by-side mounting is permitted, so you can pack contactors tight in a multi-motor panel without derating for spacing. Dimensions are 70 mm wide, 146 mm high, 152 mm deep — fits standard enclosure cutouts for the S3 frame.
Terminals and wiring
Main circuit connections are screw-type terminals. Accepts solid conductors 2x (0.25... 2.5 mm²) for control wiring and stranded conductors 2x (10... 50 mm²) for power cables. The box terminal design provides IP20 finger protection on the front with the cover installed; the terminal body itself is IP00, so maintain clearance in the enclosure.
Environmental and compliance
Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) — expected in industrial environments. RoHS compliance substance prohibition date is 05/01/2012, covering the EU RoHS directive.