SIRIUS S3 power contactor, 45 kW AC-2 motor switching
The Siemens 3RT1046-1BB44-3MA0 is a SIRIUS S3-size power contactor rated for 45 kW at 400 V in AC-2 duty and 80 A at 400 V in AC-4 duty. The AC-2 rating governs slip-ring motor switching, while the AC-4 figure covers plugging and inching of squirrel-cage motors — the higher inrush and breaking duty of those operations. Main circuit termination uses screw-type terminals accepting stranded conductors up to 2x 50 mm².
The AC-2 rating of 45 kW at 400 V is the figure to use when switching wound-rotor motors or other loads where the starting current is moderate and the break current is near rated. The AC-4 rating of 80 A at 400 V applies when the contactor must handle the high inrush of a squirrel-cage motor during plugging or jogging — a more severe duty that generates more arc energy. For less demanding AC-3 duty (starting and running squirrel-cage motors), the contactor is rated for 55 kW at 500 V and 25.4 kW at 690 V. Maximum switching frequency varies by duty class: 900 operations per hour for AC-1 resistive loads, 850 per hour for AC-3 motor starting, and 250 per hour for the severe AC-4 duty. Coil holding current at 24 V DC is 10 A, with a dropout time of 14 to 20 ms and arcing time of 10 to 15 ms.
The 70 mm width and side-by-side mounting capability mean this contactor fits standard 35 mm or 75 mm DIN rails with no additional spacing required between units. The 201 mm depth is the dimension to check against enclosure depth and gland plate clearance.