The Siemens 3RT1044-3AG60 is a SIRIUS power contactor in the Size S3 frame, rated to switch a 37 kW motor at 500 V AC-3 duty or 18.6 kW at 690 V. That AC-3 rating means it handles the inrush and breaking of squirrel-cage motors in the panel — conveyors, pumps, compressors — without derating for the inductive load.
Ratings that matter for the BOM
The AC-3 motor rating at 500 V (37 kW) is the headline number — that's the load you can switch continuously without exceeding thermal limits. At 690 V the same contactor is rated 18.6 kW, so if your line runs 690 V motors, the kW per contactor drops. The auxiliary contact block carries 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V — enough for a PLC input or a pilot light, but not for a second motor starter.
The main circuit accepts solid conductors 2x (0.25... 2.5 mm²) and stranded 2x (10... 50 mm²). IP20 on the front with the cover or box terminal; the terminal itself is IP00, so keep live parts behind a panel door. Side-by-side mounting is allowed — no derating for zero-gap stacking.