S0 power contactor for motor loads up to 11 kW
The Siemens 3RT1025-1BW44 is a SIRIUS S0-frame power contactor rated for motor switching at 11 kW at 690 V AC-3 and 10 kW at 500 V AC-3, with a 48 V DC coil. The S0 size keeps the footprint compact at 45 mm wide, 85 mm tall, and 150 mm deep — fits standard 35 mm DIN rail per EN 50022 via screw and snap-on mounting. Front-side protection is IP20; the terminal area is IP00, so plan for enclosure clearance around the wiring zone.
Coil and switching characteristics
The 48 V DC coil draws 5.4 W closing and holding power — a single-supply constant that simplifies the control transformer sizing. DC switching capability is specified per voltage: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. For AC-4 duty at 400 V the contactor handles 15.5 A, and the AC-12 maximum operating current is 10 A. Mechanical life is typical 10 million operations.
Coordination and wiring
Type 1 coordination requires a 63 A gL/gG fuse; Type 2 coordination requires 25 A gL/gG. Main circuit terminals accept screw-type connections: solid conductors up to 2x 10 mm² or AWG 8, stranded up to 2x 4 mm². Auxiliary contacts are rated for the same 48 V DC coil circuit. Side-by-side mounting is permitted with 6 mm clearance at the side.