What this contactor is and what it does
The Siemens 3RT1044-1AN64 is a SIRIUS power contactor in the S3 frame size, built for switching three-phase motor loads in industrial control panels. It carries screw-type terminals on the main circuit and is rated for 37 kW at 500 V AC-3, with a secondary rating of 18.6 kW at 690 V AC-3. The S3 size means a 70 mm width and 146 mm height, with a depth of 188 mm — a common footprint for 30–40 kW contactor duty. It mounts via screw or snap-on onto 35 mm or 75 mm standard DIN rail.
What the ratings mean for your panel
The 37 kW at 500 V AC-3 rating is the motor-switching capability — that's the current you size the overload relay and cable for. At 690 V the same contactor handles 18.6 kW, so if your line runs 690 V motors you still have a valid rating, just at lower power. The contactor is rated for side-by-side mounting without derating, which saves panel width when you need multiple contactors in a row. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C — fine for most indoor enclosures. Front IP20 with the cover fitted; the terminal area is IP00. That means the contactor body is touch-safe once the cover is on, but the wiring compartment is open — standard for panel-mount contactors. Pollution degree 3 suits industrial environments with conductive dust or occasional condensation.
Sourcing and lifecycle
We source this part to order against an RFQ. Availability and current pricing are confirmed at quote time. If you need a cross-reference for a BOM line that was specified around a different SIRIUS contactor, the 3RT1044-1FB46 is the closest functional peer — same S3 frame, same AC-3 power ratings, but with spring-type terminals instead of screw. The 70 mm width and DIN-rail footprint are identical, so it drops into the same panel layout without rewiring the main power circuit.