Siemens 3RT2027-1BW40 — SIRIUS S0 Power Contactor, 48 VDC Coil
The Siemens SIRIUS 3RT2027-1BW40 is a size S0 power contactor with a 48 VDC magnet coil, screw-type terminals, and an integrated auxiliary switch. It is rated for switching DC loads up to 10 A at 24 V (DC-13), 2 A at 48 V, and 0.3 A at 220 V, making it suitable for DC control circuits in industrial panels. The S0 frame (45 mm wide, 85 mm tall, 107 mm deep) mounts on 35 mm DIN rail per DIN EN 60715 via screw or snap-on fastening, with ±180° rotation and ±22.5° tilt allowed on vertical surfaces. The operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C.
DC Switching Ratings and Application Context
The DC-13 ratings define the contactor's capability for switching electromagnets and inductive DC loads. At 24 V the contactor handles 10 A; at 48 V it handles 2 A; at 110 V it handles 1 A; at 220 V it handles 0.3 A. These are not continuous thermal currents but switching capacities — the contactor is designed for DC control circuits where the load is a solenoid or brake coil. The 5 hp rating at 230 V AC indicates motor switching capability on single-phase AC loads. The mechanical life is rated at 10 million operations typical, with maximum switching rates of 1 000 cycles/hour for AC-1 (resistive), 750 for AC-3 (motor starting), and 250 for AC-4 (plugging/inching).
Wiring and Clearance Specifications
Main contacts accept solid or stranded wire from 1 to 10 mm² (AWG 18–8). Auxiliary contacts accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²). Minimum clearances to adjacent metalwork: 10 mm upwards, 10 mm downwards, 10 mm forwards, 6 mm at the sides. The arcing time is 10 ms; DC arcing time is 15–18 ms. The coil pick-up is at 0.8 × rated voltage (38.4 VDC) and drop-out at 1.1 × rated voltage (52.8 VDC) — ensure the control supply can deliver the pick-up current without sag.