What this coil is and where it fits
The SIRIUS 3RT1944-5AV01 is a magnet coil for Size S3 contactors, rated 400 V AC at 50 Hz with a screw terminal connection. The coil's operating voltage tolerance is 0.8 to 1.1 times the rated value, so it holds in reliably across a ±10% line swing — typical for industrial 400 V three-phase panels where the control transformer feeds the contactor coil directly.
Panel integration note
The coil mounts on the Size S3 contactor base via screw terminals — no DIN-rail footprint of its own; it is the contactor's own coil assembly. The screw terminal accepts the same wire sizes as the contactor's control circuit (2x 0.5 to 2.5 mm² solid or stranded). Verify the existing panel's control voltage is 400 V AC 50 Hz before ordering; the 0.8 to 1.1 tolerance means it holds from 320 V to 440 V, so a lightly loaded control transformer is fine.