Motor VFD Static

Merry Christmas to all. I have a Fugi VFD (110kw) supplying a motor situated adjacent to the drive. When the drive starts the motor sounds like a cat being strangled (well I assume that is the sound) and while the drive is running radio reception within 100 metres deteriates (static noises). This squealing noise is common to 7 of these drive/motor combos but the static interference is more pronounced with only one unit. The interference is with both mains powered radios and a car radio. I have tried different carrier and noise frequencies with the drives but neither improve the radio reception. The cabling froms the drive to the motor is not screened but the length is less than 1 meter and it is encosed in a metal duct.
Any ideas of extra filters etc that will negate the interference.
Regards Alan Case

I'm unclear but do you mean the one drive is 'louder' to the ear and to radio reception?

If so, I believe that drive is radiating several harmonics and the 5th harmonic is messing with the radios. What would cause that?

1)incorrect drive tuning - compare to the quietest drive/motor combo

2)drive beggining to fail - how long in service and % of duty cycle and load?

3)motor guts coming apart - has it over heated or been spun above rated RPM?

4)loose connection - re-tighten all

5)last but not least - machine binding-up

I no longer have access to a Fuji manual, but I believe there is a way set the chopper frequency to something different from the normal 4 KHz. Heck! - you said you tried that.

Sorry I can't be of help

Rod (The CNC dude)

PS. Hey you want some snow? We have plenty

The one drive is not louder to the ear but it does mess with the radio reception a lot more than the other drives.
As each drive starts the motor emits a high pitched squealing sound for approx 5 seconds ( I have never had this happen with any other brand of drive)
1)This one drive motor combo has been tuned to the same settings as the other drives (also tried every tuning combo)
2)Drive has displayed these characteristics since new
3)Not sure of motor status but think it is OK
4) Will recheck motor connections
5) I dont think it is binding as it is on a pump and the current readings are steady

Next bit I am not sure of the correct terminology: As it effects a car radio as well I was thinking that the EMF was being radiated into the air but I suppose it could be into the supply cables which would radiate to affect the car radio.
From my understanding the Fugi drives are only a volt/hertz unit.
Regards Alan

This may help

http://powerqualityanddrives.com/emi_rfi/

http://www.mtecorp.com/tutemi/tutrfi_emi_filters.pdf

Basically its an EMI/RFI noise issue that can be fixed with proper shielding and or filtering, talk to your VFD reps to see what they have used to filter out the interference in your situation.

I am not familiar enough with Fuji drives to know off-hand but I suspect that they do not come equipt with input reactors in standard configuration.

That would provide for plenty of RFI-type noise to work backward into the AC supply which would then radiate into your radios. If it is true that they don't have input reactors, it might be good for a variety of reasons including radio noise to add them. They are relatively inexpensive but will require some space to mount them.

Why one drive is worse than another is one of those unanswerables that keep us application guys awake at night. Don't look for an answer--if you get one there is no way to know if it is right and probably will offer no clear response path to solve your RFI problems anyway.

The suggestion to contact the mfgr of the drive is good but, don't be surprised if they offer little in specifics to fix it. They lay awake nights for the same reasons!

It sounds like you have already set the carrier frequencies as low as possible. It might be worth a try to set all of them to a mid-range carrier and see what happens. Then try the same with the highest carrier. Sometimes you get lucky and it all goes away at one frequency. At least the strangling cat sounds might go away to the relief of all cats in the vicinity!

Have you tried using the noisy drive to power a different motor? See if the noise follows the drive or the motor...

Drive Noise

that noise is coming from the applied voltage from the the drive to the motor which is lower than the required voltage, which u have to increase the voltage from the drive set up

Check your HF screening, the duct, motor and drive enclosure need to be all earthed using flat strip or braided straps, the strap width must be no less than 1/3 of the length. The drive input cables must be at least 300mm away from the output cables, especially if you have an input filter. Check your filter earth connections. You could be getting harmonics induced into the feeder cables from the motor cables. Look for any breakdown in the screening, poor connections etc. Any opening more than 120mm x 120mm will cause interference, are the ventilation grills screened? The motor PE cable should be away from the power cables and outside of the duct, an HF loop through the PE cable will damage the motor bearings.