The Siemens SIRIUS 3RT1044-3XF00-0GA0 is a size S3 power contactor rated for 30 kW at 400 V in AC-2 duty, making it a direct fit for slip-ring motor switching or other moderate-inrush applications where the load current stays within the AC-2 curve. It carries screw-type terminals on the main circuit and is designed for screw and snap-on mounting onto 35 mm and 75 mm standard mounting rail, so it drops into a standard DIN-rail panel without extra bracketry.
Ratings and fit
The AC-2 rating of 30 kW at 400 V is the headline number for motor-switching duty — it governs the contactor's ability to handle the starting and running currents of wound-rotor motors. At 500 V the same contactor is rated for 37 kW, and at 690 V it drops to 18.6 kW, so the voltage derating curve matters if you're running a 690 V line. The contactor measures 176 mm high by 70 mm wide by 152 mm deep, which is the S3 footprint; side-by-side mounting is permitted, so you can gang several on the rail without a mandatory gap. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. The enclosure carries IP20 on the front with the cover or box terminal fitted; the terminal body itself is IP00, so it expects to live inside a panel, not out in a washdown zone. Pollution degree 3 means it's rated for industrial environments with conductive pollution.
Wiring and terminals
Main circuit terminals accept solid conductors 2x (0.25 to 2.5 mm²) and stranded conductors 2x (10 to 50 mm²), plus a 2x (2.5 to 16 mm²) range for solid or stranded. That covers control wiring on the small end and power cabling up to 50 mm² on the large end — no need for adapter lugs on typical motor feeds up to that cross-section. The auxiliary contact block (not included with this base unit) would wire into the same screw terminal format.