The Siemens 3RT2028-1AD00 is a SIRIUS power contactor in the S0 frame size, rated for 34 A at 480 V AC-3 duty — that's the motor-switching current, so it handles a 3-phase induction motor up to roughly 20 hp at that voltage. The S0 footprint (45 mm wide, 85 mm high, 97 mm deep) fits a single 45 mm slot on the rail.
The headline number is 34 A at 480 V AC-3 — that's the rated operational current for switching standard squirrel-cage motors. AC-3 covers starting and plugging, so this contactor is sized for motor loads, not resistive heaters. The AC-1 resistive rating is higher (not listed here), but for motor duty the 34 A figure governs. The contactor is rated for 750 switching cycles per hour under AC-3 duty, adequate for normal conveyor or pump cycling. The auxiliary switch (1 NO + 1 NC, based on the 16...8 terminal marking for main contacts) allows feedback to a PLC or status indication without an add-on block.
Solid or stranded wire from 1 to 10 mm² accepted on the main terminals; auxiliary terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²).