SIRIUS 3RT1045-1AU00 — Power Contactor, Size S3
The Siemens SIRIUS 3RT1045-1AU00 is a Size S3 power contactor designed for switching motor loads in industrial control panels. It is rated for AC-2 duty at 37 kW at 400 V, meaning it handles slip-ring motor starting and reversing applications where the contactor makes and breaks the motor current at reduced inrush. The AC-4 rating at 400 V is 66 A, covering plugging and inching cycles. For AC-3 squirrel-cage motor switching, the 500 V rating is 45 kW, and at 690 V it is 21.1 kW. The contactor mounts on 35 mm or 75 mm DIN rail via screw and snap-on fastening. Side-by-side mounting is permitted, which simplifies panel layout for multi-contactor groups. The enclosure provides IP20 on the front with the cover or box terminal fitted; the terminal area itself is IP00, so it expects a panel environment where the busbars and wiring are behind a deadfront.
Key Ratings and What They Mean for Fit
The AC-2 rating at 37 kW at 400 V is the headline figure for this contactor. AC-2 duty means the contactor makes and breaks the motor current at reduced inrush — typical for slip-ring or wound-rotor motors in crane, hoist, or conveyor drives. The AC-4 rating of 66 A at 400 V covers plugging and inching, where the contactor breaks full motor current. The AC-3 rating at 500 V is 45 kW, suitable for standard squirrel-cage motors on pumps or fans. The mechanical life is 10,000,000 operations typical, with electrical life depending on the switching category and load current. The coil is rated for 50 Hz at 240 V, with an operating range of 0.8 to 1.1 times the rated voltage. Opening time is 10 to 25 ms, arcing time is 10 to 15 ms. The auxiliary contact ratings are: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V. These are the switching capacities for the built-in auxiliary contacts, not the main poles.
Wiring and Terminal Data
The main current circuit uses screw-type terminals. Solid wire connections: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded wire: 2x (10 to 50 mm²). For the auxiliary and control circuit, solid or stranded wire: 2x (2.5 to 16 mm²). The pollution degree is 3, meaning the contactor is rated for conductive pollution environments typical of industrial control panels.