VFD Pumps & Fans

Removing parts of the equipment will invalidate any remaining manufacturer's guarantee on the equipment, exposing the operation should an unexpected failure occur in service. Best not to.

I wouldn't recommend it.

Leaving off or changing VFD manufacturer-recommended filters is just asking for trouble, especially as harmonics (a very complex subject in itself) can interact with other electronic and capacitive equipment on site causing component degradation and failure.

Be vary wary of simplified or idealised harmonic calculations as harmonic distortion from other electronic equipment (including some types of lighting) can interact with each other creating a far worse harmonic mess than calculated.

Saving money on leaving out the recommended filter will likely end up costing you more money, downtime and grief in the long run. Take it from someone who used to sell and service VFDs as well as harmonic test compact fluorescent lighting - don't skimp on the filters or you will be sorry.

How long is the wire from the VFD to the motor? Your just going to have a lot less installation issues if the VFD is right at the motor. You will have a much improved noise generation problem the long connection wires cause. Also ensure the power connection to the VFD is not marginally sized. Especially if the power source is a long distance. It may be on the correct wire size, but how much IR drop is there? This is big contributor to the VFD placing motor switching noise currents onto the power system, which is communicated everywhere on that power system. Is the motor load running right at the maximum of the VFD output, as well the ampacity of the power wiring to the VFD?

I find your question very vague.

Are you planning on installing a new 30hp vfd/motor/pump ('relaxing the filter for new 30hp will cause the THD increase slightly') onto an existing distribution system, that has similar equipment already feed from it? And by comparing/measuring the THD from the current equipment ('Total Harmonic Distortion (THD) on the 480V Service which serves power to P-21 is about 2.12%. This calculated value is below the specification and IEEE requirement of 5% Maximum THD.'), you've come to the assumption that by adding the new equipment, you'll not double you're existing THD of 2.12% and, effectively not exceed the 5% limit. So you can then reduce the filtering requirements for the new equipment.

Is this a cost saving exercise? How much will you save in real terms, by reducing the filtering? Is it really worth it? Do you plan to add any more equipment to this distribution system in the future? Will you then have to go back and upgrade the filtering anyway?

The harmonic filters are not just for the device they are attached to or part of.

These filters also affect the quality of the power source the VFD is attached to.

The filters improve you power factor and save money so decreasing the filtering will cost you in performance and budget expedditures.

I would not even consider it as viable.