The Siemens 3RT1046-1AL20-1AA0 is a SIRIUS S3 power contactor — Size S3 frame, rated for motor loads up to 55 kW at 500 V (50 Hz) and 25.4 kW at 690 V (60 Hz). That 500 V rating covers most European 400 V three-phase industrial supplies with headroom; the 690 V rating is the one you care about for 600 V class panels or mining/offshore gear running on 690 V distribution. Mounts on 35 mm or 75 mm DIN rail via screw and snap-on — standard panel integration. The 70 mm width and 146 mm height fit a standard S3 footprint; depth is 139 mm including the arc chamber.
AC-3 duty (squirrel-cage motors) is the headline: 55 kW at 500 V. That's the number for sizing — a 55 kW motor on a 400 V supply draws roughly 100 A full-load; this contactor handles that all day. AC-4 reversing or inching duty maxes out at 250 operations per hour, so if you're jogging a crane or a press, stay under that cycle count. AC-1 resistive loads (heaters, lighting) allow 900 ops/h. The mechanical life is rated 10 million operations typical — the coil and armature are built for that. Coil pick-up and drop-out: at 50 Hz, the operating range is 0.8 to 1.1 x rated voltage; at 60 Hz, 0.85 to 1.1. Front face is IP20 (finger-safe with the cover/box terminal installed); the terminal block itself is IP00 — wire into it with the panel door closed or use a shrouded terminal cover.