The “rule of thumb” is that for an “unbuffered” VFD, meaning one WITHOUT a DC bus choke (as most low cost Asian drives are), you should have a Line Reactor if the source kVA is 10x the drive kVA or greater. So your smallest drive is 1kW, call it 1kVA to be simple, and your source is 75kVA, so since 75>10, you should use a Line Reactor. The thing is, you could put one large LR ahead of all 6 drives and get the desired protection. No need to put one in front of each drive.Thanks for clearing this up for me.
On a different note, this same project will have 6 single-phase input 1KW vfds in a 4 by 4 foot steel cabinet to control fans. This vfd cabinet is right beside a 200 amp sub-panel, which is fed from a 75kva Xformer located 200 feet away. I already know I'll be installing load reactors, but do i need to worry about line side reactors being that this panel is so far away from main power source. Could I install a single line reactor to handle all 6 vfds?