The Siemens 3RT5945-5AF01 is a SIRIUS replacement magnet coil for the 3RT series of power contactors. It is the field-replaceable solenoid that pulls the contactor armature in, rated for 110 V AC control supply at 50 Hz. The coil accepts a voltage tolerance of 0.8 to 1.1 times the rated value, meaning it holds in reliably from about 88 V to 121 V AC — a standard operating band for industrial control transformers that sag under load.
Integration into the contactor
Connection is via screw terminals, matching the standard 3RT contactor coil termination. The coil mounts onto the contactor magnet system; no DIN-rail space consumed beyond the contactor itself. For a panel OEM or MRO planner, this is a direct swap part — same footprint, same wiring scheme as the original coil shipped with the contactor.