The Siemens SIRIUS 3RT1024-1BB44-1AA0 is a power contactor in the S0 frame size, designed for motor switching and general load control in industrial panels. It uses a 24 V DC coil drawing 5.4 W for both closing and holding, which simplifies the control transformer sizing since there is no inrush-to-seal drop. The screw-type main circuit terminals accept solid conductors up to 2x 4 mm² or stranded up to 2x 10 mm², compatible with standard panel wiring practices.
Ratings and what they mean for fit
Rated for AC-2 duty at 5.5 kW on 400 V three-phase, this contactor handles slip-ring motor loads where starting current is moderate. The AC-4 rating of 12.5 A at 400 V covers reversing or inching duty — the more demanding switching condition that generates higher arc erosion. For resistive or lightly inductive loads, the AC-12 maximum operating current is 10 A. At 500 V and 690 V, the motor power rating holds at 7.5 kW, so the same unit can serve 400 V and 690 V installations without derating the load. The two built-in auxiliary contacts (instantaneous) are rated 10 A at 24 V DC, 6 A at 230 V AC, and 0.3 A at 220 V DC — sufficient for PLC feedback or status indication without an add-on block. For fault protection, type 2 coordination requires a gL/gG fuse of 25 A; type 1 coordination allows up to 63 A. The IP20 front enclosure protects against finger contact; the terminal area is IP00, so live parts are exposed once wired — standard for panel-mount contactors.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022. The 45 mm width and 85 mm height fit standard S0 footprint panels. Side-by-side mounting is permitted with no derating at 6 mm spacing, which keeps the panel layout dense. Operating temperature range is -25 to +60 °C, with a maximum altitude of 2 000 m; pollution degree 3 means it tolerates conductive dust or humidity typical of industrial enclosures without conformal coating.