What this part is and what it fits
The Siemens SIRIUS 3RT1944-5BW42 is a replacement magnet coil for Size S3 contactors in the SIRIUS family. It is a 48 V DC coil with spring-loaded (cage-clamp) terminals, designed to be swapped into an existing S3 contactor when the original coil fails or when a control voltage change is needed.
Lifecycle reality — phased out, successor named
This order code is explicitly marked as a phased-out product. The manufacturer's designated successor is the SIRIUS 3RT2 series. For a BOM line that must stay with the S3 platform, sourcing this specific 3RT1944-5BW42 coil through the independent channel is the practical path — it is quoted to order against an RFQ, not stocked as a current-production item.