SIRIUS 3RT1023-1BF44 — 110 VDC Coil, S0 Frame Power Contactor
The Siemens 3RT1023-1BF44 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads in control panels. Its 110 VDC coil draws 5.4 W closing and holding, so the control transformer or DC supply must be sized for that continuous draw — no inrush spike beyond the holding power, which simplifies the DC rail budget. Rated for AC-3 duty at 4.5 kW on 400 V three-phase and 5.5 kW at 690 V, this contactor handles standard induction motors up to those power levels. The AC-4 rating of 8.5 A at 400 V covers reversing or plugging applications where the contacts break full motor current. For resistive loads (AC-12), the maximum operating current is 10 A. Mounting is screw and snap-on onto 35 mm DIN rail per EN 50022. The 45 mm width and 85 mm height fit a standard S0 footprint; side-by-side mounting is allowed with 6 mm clearance at the side. Front protection is IP20; the terminals themselves are IP00, so the panel enclosure provides the environmental seal.
Motor Duty and Coordination
For AC-3 motor starting at 400 V, this contactor delivers 4.5 kW — that is the rating that governs the real motor load, not the AC-1 resistive figure. The AC-2 rating of 4 kW at 400 V applies to slip-ring motors or wound-rotor applications where the load current is lower but switching frequency may be higher. Short-circuit coordination: with type 2 coordination, a gL/gG fuse rated 25 A protects the contactor; type 1 coordination allows a 63 A fuse. The pollution degree 3 rating means the contactor is suited for industrial environments where conductive dust or condensation may be present.
Terminal and Wiring Details
Main current circuit terminals are screw-type, accepting 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max. 2x 10 mm² stranded. Auxiliary contact terminals accept 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²), or max. 2x (0.75 to 4 mm²). AWG equivalents: main contacts 2x (16 to 12), 2x (14 to 10), 1x 8; auxiliary contacts 2x (20 to 16), 2x (18 to 14), max. 2x (18 to 12).
Environmental and Mechanical Limits
Operating temperature range is -25 to +60 °C, with storage limits extending beyond that. Maximum operating altitude is 2,000 m without derating. Mechanical endurance is 10 million operations typical. The reference code per DIN EN 81346-2 is Q (power switching device).