SIRIUS 3RT2028-1AV04 — size S0 power contactor, 34 A at 480 V
That 34 A figure is the AC-3 motor-switching current — the rating that governs real motor loads, not the higher resistive-heating number.
Mounting and wiring — DIN rail, conductor range, spacing
Solid or stranded conductors from 1 to 10 mm² accepted at the main terminals; for the coil circuit, two conductors per clamp from 0.5 to 2.5 mm². Minimum air clearance: 10 mm upwards, downwards, and forwards; 6 mm at the sides. That 6 mm side gap is tighter than some S0 peers — check side-by-side spacing if you are packing multiple contactors on a DIN rail without separators.
Thermal limits and operating envelope
Lifecycle status is current production.
Switching frequency and mechanical endurance
Rated switching frequency: 1 000 cycles/hour at AC-1 (resistive), 750 cycles/hour at AC-2 and AC-3 (motor starting and running), 250 cycles/hour at AC-4 (plugging/inching). The AC-4 limit is the one that catches people — if you are jogging or reversing a load frequently, the contactor needs to be sized for that duty class, not the AC-3 number. Mechanical life typical is 10 million operations; the arcing time on opening is 10 ms, which is tight enough for most coordination studies with upstream motor circuit protectors.