The Siemens 3RT1944-5AL21 is a SIRIUS magnet coil — the replaceable solenoid that pulls in the contactor armature. It's sized for Size S3 contactors and terminates via screw terminals.
The 0.8... 1.1 figure at 50 Hz is the operating voltage range as a factor of the rated coil voltage (230 V). That means the coil reliably picks up and holds between roughly 184 V and 253 V AC — a ±15% tolerance that covers typical line sags without dropping out. The same 230 V rating applies at 60 Hz, so it's a straight swap across 50/60 Hz regions.
Deployment context
The screw terminals match existing panel wiring practices — no crimp-tool change needed for the control circuit.