What it is and what it does
The Siemens 3RT1046-1AQ20 is a SIRIUS power contactor in frame size S3, designed for switching motor loads in industrial control panels. Its AC-3 rating of 55 kW at 500 V and 25.4 kW at 690 V tells you the motor currents it can handle under full-load starting and running — the rating that governs real-world motor duty, not just resistive heating. The main circuit uses screw-type terminals, and the front face carries IP20 protection with the cover and box terminal in place, which is the standard for enclosed panel mounting.
Mounting and integration
Mounts via screw or snap-on onto 35 mm or 75 mm standard mounting rail — the DIN-rail footprint that fits most European-style enclosures. Dimensions are 146 mm high, 70 mm wide, 139 mm deep, so it occupies a standard S3 slot on the rail. Side-by-side mounting is allowed, which saves rail space when grouping multiple contactors in a motor control centre.
Wiring and termination
Main circuit screw terminals accept solid conductors up to 2x 4 mm² (or 2x 1.5 mm² minimum) and stranded conductors up to 2x 50 mm² — that covers the range from control wiring up to the motor feed cable for a 55 kW load. Auxiliary contact ratings are given for both AC and DC: 10 A at 24 V DC, 6 A at 230 V AC, 3 A at 400 V AC, so you can size your control transformer and pilot devices accordingly.
Environmental and service life
Rated for operating ambient -25 to +60 °C, storage -55 to +80 °C, and pollution degree 3 — that means it's suitable for industrial environments with conductive dust or occasional condensation, not just clean control rooms. Mechanical service life is 10 million operations typical; switching frequency at AC-3 duty is up to 850 cycles per hour, so it handles frequent start-stop applications like conveyors or pumps without derating.