The Siemens SIRIUS 3RT2027-2BM40 is a size S0 power contactor with spring-type terminals, designed for screw and snap-on mounting onto 35 mm standard mounting rail per DIN EN 60715. It occupies a 45 mm width on the rail, with a depth of 107 mm and height of 102 mm, fitting standard panel layouts without overhang.
Switching Ratings and Duty Cycles
Rated for AC-1 resistive loads at up to 1,000 switching cycles per hour, AC-2 and AC-3 motor duty at 750 cycles/h, and AC-4 (inching/plugging) at 250 cycles/h. The AC-3e rating also holds at 750 cycles/h. For DC switching, the contactor breaks 10 A at 24 V, 2 A at 48 V and 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 — covering common control voltages in industrial DC bus and battery-backed circuits.
Environmental and Mounting Flexibility
Operates from -25 °C to +60 °C and stores from -55 °C to +80 °C. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, so it fits tight enclosures or angled subpanels. Clearances: 10 mm upwards, forwards, and downwards; 6 mm at the sides — useful when packing multiple contactors side-by-side.
Termination and Wiring
Spring-type terminals accept solid or stranded conductors from 1 to 10 mm², and two conductors of 0.5 to 2.5 mm² each. The auxiliary switch is built in (18…8 main contacts), eliminating the need for a separate add-on block for basic signaling.