SIRIUS S0 power contactor — what it is and where it fits
The Siemens SIRIUS 3RT2028-1BF40-0JA0 is a size S0 power contactor with a 110 V rated-value coil and screw-type terminals. It mounts on 35 mm DIN rail per DIN EN 60715, with ±180° rotation and ±22.5° tilt possible on a vertical surface. At 45 mm wide and 107 mm deep, it fits standard panel layouts and leaves room for auxiliary contact blocks. The contactor handles main-contact wire sizes from 1 to 10 mm² solid or stranded, and accepts dual conductors down to 0.5 mm² for auxiliary wiring. Switching frequency reaches 1000 cycles/hour at AC-1 resistive load, 750 cycles/hour at AC-3 motor duty, and 250 cycles/hour at AC-4 inching duty — the AC-3e rating matches the same 750 cycles/hour for standard motor-start applications.
Terminal and mounting details
Screw-type terminals on both main and auxiliary circuits. Main contacts accept 1–10 mm² solid or stranded; auxiliary contacts accept dual conductors 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²). Mounting is screw-and-snap-on to 35 mm DIN rail per DIN EN 60715. Clearance: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side. Height is 85 mm.
Auxiliary contact ratings and switching performance
The auxiliary switch is rated for DC switching: 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 3 A at 400 V. Arcing time is 10 ms. Mechanical life is 10 million operations typical. Storage temperature range is -55 to +80 °C; operating range is -25 to +50 °C.