Can one passive filter be used on multiple loads?
It is possible to use one large passive harmonic filter (PHF) to feed a number of VFD loads at the same time provided all the VFD loads are connected to a feeder that only has VFD loads on it and the VFDs always run together.
If it is not possible to isolate the VFDs from other linear loads you cannot use one large PHF because the THDv on the output of a PHF is distorted to an extent which will cause some linear loads to be damaged (E.g. fixed speed AC motors that are connected across the line). Computers, PLC controls and instrumentation can also be damaged by excessive THDv.
The price for one large PHF will generally be lower than the total cost of a large number of smaller PHFs.
The installation cost for one large PHF is less than the total cost of installing a large number of small PHFs.
The losses in one large PHF are lower than the total losses for a large number of small PHFs.
