The Siemens 3RT1944-5AD02 is a SIRIUS magnet coil designed for Size S3 contactors. It provides the 42 V AC 50 Hz control voltage to pull in and hold the contactor armature, using spring-loaded connection technology for the coil terminals — no screwdriver needed on the coil wiring. This coil is a replacement or spare part for SIRIUS Size S3 contactors already in the field. The 0.8... 1.1 range at 50 Hz refers to the operating voltage tolerance band (80% to 110% of rated voltage), meaning the coil reliably picks up at 33.6 V and holds in up to 46.2 V.
Lifecycle reality — phased out, successor known
This part is a phased-out product. The manufacturer lists the lifecycle stage as current but the description explicitly marks it as a phased-out product with a successor: the SIRIUS 3RT2 series.
Panel integration — spring-loaded terminals
Spring-loaded connection technology on the coil terminals accepts solid or ferruled stranded wire without screw clamping. This speeds wiring on the panel assembly line and eliminates the risk of screw loosening from vibration on a contactor that cycles frequently.