The Siemens SIRIUS 3RT2028-2AF00 is a size S0 power contactor rated for 34 A at 480 V in AC-3 duty — that's the motor-switching current, not the resistive load rating.
AC-3 at 480 V is the headline: 34 A continuous motor load, 750 switching cycles per hour max. That's the figure that decides whether this contactor handles your 15–20 kW induction motor on a 480 V line. AC-1 resistive rating is higher but not the binding constraint for motor circuits. Switching frequency varies by duty: 750 cycles/h for AC-2 and AC-3, 250 for AC-4. AC-4 is plugging and inching duty. The auxiliary switch configuration is 1 NO + 1 NC on the main contact block (18... 8 notation means 18 terminals for the main poles, 8 for aux). Coil draw at 50 Hz is 0.25 A — useful for sizing your control transformer.
That 6 mm side gap is tighter than some contactors; check your enclosure layout before committing. Wire range: solid 1–10 mm², stranded 1–10 mm², and 2×(0.5–2.5 mm²) for daisy-chaining smaller conductors. Spring-type terminals on the coil — no screw torque to verify, but strip length matters more with spring clamps.