The Siemens 3RT1944-5AC21 is a SIRIUS magnet coil designed for Size S3 contactors. The coil draws an inrush current of 0.8 to 1.1 A at 50 Hz, which is the peak current the control transformer or PLC output must handle during pickup.
The 0.8 to 1.1 A at 50 Hz is the inrush (closing) current, not the holding current. The holding draw is significantly lower — the coil's apparent holding power is around 12.5 VA on the S2-size sibling (3RT1036-1AB00), and the S3 coil here will be similar. This matters when sizing the control transformer: the inrush pulse is brief but must not drop the supply voltage below the coil dropout threshold (typically 18 V AC for a 24 V nominal coil).
The coil mounts on a Size S3 contactor via screw terminals. When replacing a failed coil in an existing panel, confirm the contactor frame size — the 3RT1944-5AC21 fits only S3 frames, not S0 or S2. The screw terminal accepts 2x (0.5 to 1.5 mm²) solid or stranded, or 2x (0.75 to 2.5 mm²) with ferrule.