VFD Help
VFD Help
(OP)
Hello everyone,
I am working on a project which I have been parachuted into. The electrical system is a mess as it was never properly designed and what design there was was not followed very closely. There is no separation of power/signal conductors in the cable tray and no cinsistency in the sheilding of the conductors. The system is powered by 3 synchronized gensets, 400/230 VAC, 50 Hz. My concern at the moment is the VFDs installed in the system. I do not know if they have any reactance installed in them, but I do know that while the design did call for sheilded cable the installation is inconsistent on this. Most of the VFDs are powering fractional hp motors, but two of them are powering 30 hp pumps.
My concern is noise and harmonics generated on the line side and EMF generated in the cable tray runs. I know that the larger vfd's will need to be dealt with, but do I have to worry about the smaller ones (there are about 4 of them) creating a larger problem as a whole than they would individually?
Does anyone know and good web resources or have any tips for me on this one?
I am working on a project which I have been parachuted into. The electrical system is a mess as it was never properly designed and what design there was was not followed very closely. There is no separation of power/signal conductors in the cable tray and no cinsistency in the sheilding of the conductors. The system is powered by 3 synchronized gensets, 400/230 VAC, 50 Hz. My concern at the moment is the VFDs installed in the system. I do not know if they have any reactance installed in them, but I do know that while the design did call for sheilded cable the installation is inconsistent on this. Most of the VFDs are powering fractional hp motors, but two of them are powering 30 hp pumps.
My concern is noise and harmonics generated on the line side and EMF generated in the cable tray runs. I know that the larger vfd's will need to be dealt with, but do I have to worry about the smaller ones (there are about 4 of them) creating a larger problem as a whole than they would individually?
Does anyone know and good web resources or have any tips for me on this one?





RE: VFD Help
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: VFD Help
The total harmonic current distortion caused by the VFDs is proportional to the total load power delivered by the VFDs compared to the overall total load power delivered at the utility metering point. The total voltage distortion is proportional to the total load power delivered by the VFDs compared to the capacity of the power source.
For additional information, start with the manufacturer's installation manuals for the VFDs. See if you can download them or otherwise obtain them if you don't have them. Read them carefully and obtain any additional material mentioned in them. Check the manufacturer's web sit for any additional material that might be available.
RE: VFD Help
Answer #2 - this is a shipboard application, under DNV jurisdiction, which is based on and references the IEC code.
thanks for the quick replies so far.
RE: VFD Help
RE: VFD Help
RE: VFD Help
RE: VFD Help
Various manufacturers of drives and harmonic mitigation equipment have downloadable tools for estimating harmonic distortion. You may or may not need drive input reactors to avoid problems. The small drives probably don't need reactors unless there are a lot of them.
As difficult as it might be, you may need to put in shielded motor cable for all of the drives or figure out how to separate the motor cables from everything else.
RE: VFD Help
NEMA Application Guide for AC Adjustable Speed Drive Systems
http://www.nema.org/stds/acadjustable.cfm (free download)
Shielded Motor Cable
http://www.lappgroup.com Ölflex-Servo-FD 780 CP
http://www.lappusa.com/sect6contents.htm
http://www.nkclub.com MCCMK
http://www.belden.com 295xx (eCatalog-Industrial-VFD Cable)
http://www.alphawire.com/pages/indser3page8.cfm
Reactors and Filters
http://www.transcoil.com TCI – Trans-Coil, Inc.
http://www.hammondpowersolutions.com Hammond Power Solutions, Inc.
http://www.mirusinternational.com Mirus International, Inc.
http://www.mtecorp.com MTE Corp.
http://www.bonitron.com Bonitron, Inc.