The Siemens 3RT2028-2AC24 is a SIRIUS S0 power contactor with a 24 VDC coil, spring-type terminals for the magnet coil, and screw and snap-on mounting onto 35 mm standard mounting rail per DIN EN 60715. It's sized for a 3-pole motor load up to 5 hp at 230 V or 3 A at 400 V, with a mechanical life of 10 million cycles typical.
The 24 VDC coil draws 6 A at rated value — that's the inrush to hold in, not the steady-state seal current. Switching frequency limits are 1000 cycles per hour for AC-1 resistive loads, 750 for AC-3 motor starting, and 250 for AC-4 plugging/reversing. That 750 1/h on AC-3 means it handles a conveyor start every 4.8 seconds continuously — plenty for most material-handling lines. That's useful when you're fitting it into a tight gland-plate layout and the rail isn't perfectly vertical. The 60 °C ceiling means it's fine inside a non-ventilated enclosure up to that ambient — no derating needed unless you're stacking contactors side-by-side.
The 3RT2028-2AC24 is a straight-ahead active SKU from the SIRIUS portfolio. No cross-reference needed for a replacement; it's the part you spec today.