What this contactor is and what it does
The Siemens 3RT1046-1BG40 is a SIRIUS power contactor in size S3, built for switching motor loads in industrial control panels. Its AC-2 rating at 400 V is 45 kW — that's the duty for wound-rotor motors where the contactor makes and breaks the rotor circuit under load. For AC-3 squirrel-cage motors, the power rating climbs to 55 kW at 500 V. The contactor also carries an AC-4 rating of 80 A at 400 V for plugging and inching applications that hammer the contacts harder. The main current circuit uses screw-type terminals. The contactor mounts by screw or snap-on onto 35 mm and 75 mm standard mounting rail. Side-by-side mounting is allowed. Mechanical life is rated at 10,000,000 operations typical.
Terminal and environmental specs
The contactor accepts solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and max 2x (0.75 to 4 mm²). For stranded wire, it takes 2x (10 to 50 mm²). There's also a solid-or-stranded range of 2x (2.5 to 16 mm²). The enclosure rating is IP20 on the front with cover or box terminal, and IP00 at the terminal itself — so the panel builder needs to account for the open terminal area in the overall IP strategy. Pollution degree 3 means it's suited for industrial environments with conductive pollution. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C.
Dimensions and mounting
Dimensions are 146 mm height, 70 mm width, and 152 mm depth. The depth figure is the one to watch when laying out the panel — at 152 mm, it needs clearance behind the rail for the contactor body and wiring. The fastening method accepts both screw fixing and snap-on onto 35 mm and 75 mm standard mounting rail, which covers the two most common DIN rail profiles in industrial panels.