Siemens 3RT2028-1AH20 — SIRIUS Power Contactor, Size S0
It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward/backward — useful when you're squeezing it into a crowded panel and the gland plate is in the way. Rated switching frequency varies by duty: up to 1,000 cycles/hour at AC-1 (resistive loads), 750 cycles/hour at AC-2 and AC-3 (motor starting/running), and 250 cycles/hour at AC-4 (plugging/inching). That AC-4 ceiling is the one that matters if you're jogging a conveyor or reversing a pump — exceed it and the arc chute takes a hit. Wire range accepts solid or stranded 1–10 mm² for the main circuit, and 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²) for auxiliary contacts.
Panel Fit & Thermal Reality
At 45 mm wide and 97 mm deep, this S0 frame slots into a standard DIN-rail footprint. That side gap is tight — if you're packing contactors side-by-side, derate the thermal current or leave a 10 mm air gap between rows. The storage number is for handling, not running — don't let the panel ambient climb past 60 °C.