Hi,
Does the VFD produce noise even when the spindle is not running ?
No, I should think not anyway. The VFD starts to draw significant current only when the motor runs, and then it draws
current from the supply in short high current bursts rather than smoothly and that causes EMI. A line reactor 'smooths'
out the current and incidentally much improves the power factor.
When the motor is not running and the VFD is sitting idle there will still be a small amount of current draw as the auxillary
flyback inverter draws a few mA's to supply the VFD with a DC power supply. I would not expect EMI from that source
to cause your problem. If it does you are going to have a real battle when the motor runs and REAL current gets drawn!
On large industrial VFDs the AC supply to be used to convert to DC for the VFDs control circuits is separate to the main
AC input. That would allow much tighter filtering of the AC to DC supply without having to use hugely outsized and
expensive components should they have to withstand full input current.
Craig