What It Is and What It Does
The Siemens 3RT2027-2BB44 is a SIRIUS power contactor in the S0 frame size. It mounts on 35 mm DIN rail per DIN EN 60715, using screw or snap-on fastening, and accepts solid or stranded wire from 1 to 10 mm² on the main contacts. The coil is 24 VDC with spring-type terminals, rated to pick up at 0.8 x the rated value and hold at up to 1.1 x the rated value. No built-in auxiliary switch is fitted.
Key Ratings — What They Mean for the Buyer
The headline motor rating is 5 hp at 230 V, which is the AC-3 duty point for a standard squirrel-cage motor. That tells you the contactor is sized for a 3–4 kW motor on a 230 V three-phase line. For DC switching, the rated breaking currents drop sharply with voltage: 6 A at 24 VDC, 2 A at 48 V, 1 A at 110 V, 0.3 A at 220 V — this is the DC-13 rating for switching solenoids and electromagnets. If your load is DC, the 24 VDC figure is the one that governs fit. Switching frequency limits are: 1 000 cycles/hour for AC-1 resistive loads, 750 cycles/hour for AC-2 and AC-3 motor loads, and 250 cycles/hour for AC-4 reversing or inching duty. The AC-3e rating at 750 cycles/hour applies to energy-efficient IE3/IE4 motors with higher inrush. Mechanical life is 10 million operations typical, so this is a long-life component for continuous cycling.
Mounting and Clearance — Panel Integration
The contactor occupies 45 mm width on the DIN rail. Height is 102 mm, depth is 154 mm. Clearance needed: 10 mm above and below, 10 mm forward, 6 mm at the sides. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt. Operating temperature is -25 to +60 °C; storage range is -55 to +80 °C.