VFD noise
VFD noise
(OP)
I have an electrical room with many large VFD's(200+hp). We know we have a problem with install (not grounding the shields on the power cables correctly) and need to fix this issue. I was wondering if someone could suggest a measurement means (EMC/EMI meter) to quantify the fixes and record the before and after.
Thanks
Thanks





RE: VFD noise
RE: VFD noise
RE: VFD noise
If by noise you mean Radio Frequency interference then you need something to measure HF band and these are not typically handheld. You would need an oscilloscope and also the knowledge as to where to measure.
EMI comes in two distinct areas: radiated and conducted emission and conducted emission is a lot easier to measure than radiated, when you know the limits you need to adhere to and what would specifically be a problem.
Usually you are measuring 'where you have problems'. For example, if you have serial communications controlling your VFD's and this is via a RS485 network. You would pop your scope on the RS485 signal and look for deformation of the waverform and "grass" on the top of the peaks as this is a likely indication that you are getting RFI onto your commsn network.
It is a wide ranging topic and issue and does require specialist help and equipment.
A useful booklet, is this one published by GAMBICA:
http://