Hi Roger,
yes and no...Small VFDs have input filters in them already, usually just, and I mean JUST comply with reflected noise requirements and no more.
Large VFDs the user is expected to select the reactors/filters to suit. Thus if you have your own transformer then line reactors become redundant, you
use the leakage inductance of the transformer. If sharing a distribution transformer with other users will require reactors and if your neighbhour has
some sensitive equipment you will be required to install them.
The amount of noise a VFD produces is proportional to its output power. Ten 10kW VFDs produce as much hash as one 100kW unit. The smaller units
will have some filtration but some cheapskate will install the 100kW unit with nothing if he can get away with it. Does it really matter to you if the hash
interfering with your machine controls is your own 10 kW unit or the neighbhours 100kW unit?
I don't know whether you listen to AM radio much, I do when I drive and in certain rural areas the interference drowns out even the strongest stations.
Craig