The Siemens 3RT1046-1BW44 is a SIRIUS-branded power contactor in the S3 frame size, designed for switching motor loads in industrial control panels. It mounts via screw fixing or snap-on onto 35 mm and 75 mm standard mounting rails, making it straightforward to integrate into a DIN-rail enclosure layout.
Key ratings and what they mean for fit
The headline motor-switching rating is 45 kW at 400 V in AC-3 duty — that is the standard category for starting squirrel-cage induction motors, so this contactor handles motor loads up to that power level without derating. For AC-4 duty (plugging, inching, reversing), the rated operational current is 80 A at 400 V, which governs the thermal stress during high-frequency reversing cycles. At 500 V it is rated for 55 kW, and at 690 V for 25.4 kW, covering the common European and North American line voltages. For DC switching, the contactor is rated at 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — these values drop rapidly with voltage, so verify the DC load curve if your circuit is not resistive. The contactor carries a pollution degree of 3, meaning it is rated for the conductive pollution typical in industrial control rooms and panel environments. The IP20 rating on the front with cover or box terminal means finger-safe protection from the front; the terminal area itself is IP00, so live parts are exposed during wiring — standard for panel-mount contactors. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C, covering most indoor and sheltered outdoor installations. Power dissipation is 37 W at 1000 V — relevant for thermal management inside a sealed enclosure.
Termination and wiring
Main power circuit uses screw-type terminals. The contactor accepts solid conductors from 2x (0.5 to 1.5 mm²) up to max 2x (0.75 to 4 mm²) for control wiring, and stranded conductors from 2x (2.5 to 16 mm²) up to 2x (10 to 50 mm²) for the main circuit. That range covers most panel wiring from control circuits up to 50 mm² motor feeders.
Mechanical life and switching frequency
Typical mechanical life is 10 million operations. Maximum switching frequency varies by duty: 900 cycles per hour at AC-1 (resistive), 850/h at AC-3 (motor starting), 350/h at AC-2, and 250/h at AC-4 (reversing). Arcing time is 10–15 ms, and the DC operating time is 14–20 ms.