The Siemens SIRIUS 3RT1046-3AF00 is a Size S3 power contactor rated for motor switching up to 55 kW at 500 V in AC-3 duty and 45 kW at 400 V in AC-2 duty — that covers the bulk of medium-horsepower three-phase induction motors you'd find on pumps, fans, and compressors in a 12-person shop like mine. It also handles 80 A in AC-4 at 400 V, which is the heavy inching and plugging duty that eats lesser contactors alive. The coil pulls 110 V at 50 Hz, so it drops right into a standard control transformer secondary.
What the ratings actually mean for your panel
AC-4 cycles are harder on the arc chamber, and this contactor is rated for 250 operations per hour in that duty. Screw terminals accept solid wire from 0.25 mm² up to 2.5 mm² (two conductors) and stranded up to 50 mm² (two conductors) — that's enough for the main power feed on a 55 kW motor circuit.