SIRIUS Power Contactor, Size S3 — 3RT1044-1BM40
The Siemens 3RT1044-1BM40 is a SIRIUS power contactor in size S3, rated for 37 kW at 500 V and 18.6 kW at 690 V, making it suitable for switching three-phase motor loads in industrial control panels. It mounts via screw or snap-on onto 35 mm or 75 mm standard mounting rail, and the main current circuit uses screw-type terminals accepting solid conductors up to 2x (0.5...1.5 mm²) or stranded up to 2x (10...50 mm²).
Integration & Mounting
The contactor occupies a 70 mm wide footprint on the DIN rail, with a depth of 152 mm and height of 146 mm. Side-by-side mounting is permitted, so multiple units can be ganged without additional spacing. The operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C.
Terminal & Wiring
Screw-type terminals on the main circuit accept solid conductors: 2x (0.5...1.5 mm²), 2x (0.75...2.5 mm²), max. 2x (0.75...4 mm²). Stranded conductors: 2x (10...50 mm²). The auxiliary circuit terminals accept 2x (2.5...16 mm²) solid or stranded. Degree of pollution is 3, and the front face carries IP20 protection (IP00 at the terminal).