What it is and what it does
The Siemens 3RT1044-1AN10 is a SIRIUS S3 power contactor with screw-type terminals for the main current circuit. It's rated for motor switching in industrial control panels, with an AC-4 rating of 55 A at 400 V, meaning it handles the toughest reversing and inching duty cycles where the contactor makes and breaks motor current under full load. That AC-4 figure is the one that matters for a crane hoist or a conveyor jog station — it's the real-world limit for plugging and inching, not the optimistic AC-3 number.
Panel fit and mounting
This is a screw-and-snap-on mount onto 35 mm or 75 mm standard DIN rail — the same footprint as any SIRIUS S3 frame. At 70 mm wide and 146 mm tall, it'll drop into existing panel layouts without re-drilling. Side-by-side mounting is supported, so you can gang multiple contactors on the same rail for multi-motor groups. The front is IP20 with the cover or box terminal fitted, which is the usual protection for inside a cabinet. The terminal area itself is IP00, so keep that in mind during installation — no live parts exposed outside the enclosure.
Wiring and terminations
Screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²) maximum. For stranded wire, it handles 2x (10 to 50 mm²) — that's the main power feed. The control circuit terminals are sized for 2x (2.5 to 16 mm²) solid or stranded. That's plenty of lug space for a 55 A contactor; you won't be fighting undersized wire clamps.
Environmental and compliance
Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 means it's rated for industrial environments with conductive dust or condensation — no need for a sealed enclosure unless the panel is outdoors in a corrosive area. The part is RoHS compliant per the substance prohibition date of May 1, 2012.