SIRIUS Size S0 power contactor — 21 A at 480 V AC-3
The Siemens SIRIUS 3RT2026-1AF04 is a Size S0 power contactor rated 21 A at 480 V in AC-3 duty — that's the motor-switching current, not the resistive-heater current. AC-3 is the standard motor-load rating (starting and disconnecting running motors), so this contactor handles a 3-phase motor pulling up to 21 A under full load at 480 V. Snap-on mounting onto 35 mm DIN rail per DIN EN 60715, plus screw terminals on the magnet coil. No auxiliary switch block included — the main contacts are the only switching path. Operating temperature range -25 to +60 °C.
Integration into the panel
Size S0 footprint: 45 mm wide, 85 mm tall, 141 mm deep. Clearances: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the sides. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when the panel layout forces an orientation other than vertical. Wire range: solid or stranded 1–10 mm² for the main circuit; auxiliary wiring accepts 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²) solid/stranded. Arcing time 10 ms at AC. Mechanical life typical 10 million operations.