SIRIUS S0 power contactor — 3RT2027-1BP40
The Siemens SIRIUS 3RT2027-1BP40 is a Size S0 power contactor with a 230 V AC coil and screw-type terminals, designed for snap-on mounting onto 35 mm DIN rail per DIN EN 60715. It occupies a 45 mm wide footprint, making it a standard panel-building block for motor control centers and distribution boards. Rated for a 10 A switching capacity at 24 V DC, it handles DC loads like solenoid valves and brake coils in the same panel. At higher DC voltages the rating drops — 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V — so keep the load curve handy when specifying for a mixed DC bus. The arcing time sits at 10 ms, and the contactor is rated for 10 million typical mechanical operations.
Duty-cycle and switching frequency
Maximum switching frequency depends on the load type: 1,000 operations per hour at AC-1 (resistive), 750 per hour at AC-2 and AC-3 (motor starting/running), and 250 per hour at AC-4 (plugging/inching). The AC-3e rating also allows 750 ops/h.
Main contacts accept solid or stranded conductors from 1 to 10 mm²; auxiliary contacts take 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with screw terminals. Clearance distances: 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side — enough for standard cable bending radius in a 45 mm slot.