Coil voltage tolerance — what that 0.8 … 1.1 means on the line
The 3RT5945-5AR61: The 0.8 … 1.1 at 50 Hz is the voltage tolerance band for the magnet coil, not a current or power figure. On a 400 V nominal coil, that means the pickup and hold voltage can sag to 320 V or rise to 440 V without the contactor dropping out or overheating. That's a wider window than most IEC contactor coils — useful in plants with weak distribution or long cable runs where voltage drop at startup is real.
AC coil — why the control voltage type matters
This is an AC coil — it's designed for a 50/60 Hz control supply, not DC. If your panel runs 24 VDC for the PLC outputs and safety relays, this coil won't pick. The 400 V at 50 Hz and 440 V at 60 Hz ratings mean it's built for standard European and North American control transformers. On a 60 Hz line, the coil draws less current at the higher voltage, so the VA demand from the control transformer drops slightly — but the mechanical pull-in force stays the same.
SIRIUS size S3 — mechanical fit for the contactor frame
This coil is the replacement magnet coil for the SIRIUS size S3 contactor and overload relay range. The S3 frame covers contactors from about 38 A to 65 A AC-3, depending on the ambient. If you're swapping a burnt coil on a 3RT1 contactor in that frame, this is the direct fit — same winding, same mounting tabs, same armature stroke. No adapters or bracket mods needed.