# Buzzing noise after VFD conversion



## 7milesup (Jun 26, 2022)

After collecting all my electrical parts I was finally able to get my (new to me) Sharp knee mill running today.  It was a bit of a process with the wiring and the programming of the VFD, which is a Lapond brand.  https://www.amazon.com/dp/B075M8R77M?ref=ppx_yo2ov_dt_b_product_details&th=1

The issue is there is a buzzing noise emanating from the motor.  It is about the same frequency as my tinnitus, so I had to have my daughter come and take a listen.  Yep, it is there.  One of the parameters that I changed in the VFD was the "carrier frequency" from 12kHz to 16khz, which helped ever so slightly, but not enough. If I lower that number below 10kHz the buzzing becomes prominent.  

Would anyone have any thoughts on what else could be causing that, or is this just the way it is?  The motor on this mill is a 230v, 3ph, 8A, 1720rpm flavor, and the original motor I might add, which I would like for it to stay that way.  I am considering purchasing a different VFD but not sure if that would make any difference.  Would love to get a Durapulse from Automation Direct but it seems that they are perpetually out of stock.  I am considering a Teco or a Hitachi, but maybe that would not make any difference other than I could then say I have a "name brand."


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## rabler (Jun 26, 2022)

Usually changing the carrier frequency fixes the issue.  That has worked for me with Teco units. A filter(choke) between the vfd and motor may help if the vfd manufacturer supports such a thing.  Others with more experience may have better advice.


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## mksj (Jun 26, 2022)

High frequency pitch is from the carrier frequency, most of use it is not noticeable after 12kHz. Also make sure you auto tune the VFD to the motor, this can tweak the VFD internal parameters and it can make the motor run smoother and quieter. The noise is more prominent the lower the Hz setting.


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## 7milesup (Jun 27, 2022)

I watched a Clough42 video where James talked about the carrier freq. and how it affected the noise so that is what clued me in on it.  I am having issues with the auto-tune function, Mark. For some reason it will not complete the process but rather, it just runs in reverse for about 15 seconds and then that is it.  According to the manual, the process should take nearly 2 minutes with it running the motor in both forward and reverse.  
Would the Schaffner filter that you sent a link to me help in this, or would that primarily just help with any ancillary systems such as the CNC controls?  *Schaffner RFI Power Line Filter*.  The CNC controls are fully shielded BTW.
I am very close to pulling the trigger on a WEG VFD from Automation Direct, more because they have a programming software package that looks amazing.  *WEG CFW300 VFD*. The TECO is also very tempting.


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## mksj (Jun 27, 2022)

A line filter will have no effect, that is on the input side. What Rabler mentioned is called a dV/dT filter between the VFD output and the motor (sometimes called sine filters) but these are more for longer cables to decrease the voltage spikes to the motor, they are also used for older motors to decrease the risk of insulation breakdown. I have had a few people use them, but did not make any changes to the motor performance or noise.  The reason for your auto-tune running shorter is because it is running it static as opposed to dynamic. The latter requires the motor to not be connected to a load so the motor can turn. I would live with it for now, all VFD's have some degree of wine which is a high frequency buzz. Set the carrier frequency to the maximum, it will not cause any motor issues with newer motors. You could also try increasing the motor speed to 80 Hz and see if that helps.









						What are DV/DT Filter Reactors?
					

Please enter sub title for DV DT Filter Reactors




					americas.hammondpowersolutions.com


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## stupoty (Jun 27, 2022)

7milesup said:


> After collecting all my electrical parts I was finally able to get my (new to me) Sharp knee mill running today.  It was a bit of a process with the wiring and the programming of the VFD, which is a Lapond brand.  https://www.amazon.com/dp/B075M8R77M?ref=ppx_yo2ov_dt_b_product_details&th=1
> 
> The issue is there is a buzzing noise emanating from the motor.  It is about the same frequency as my tinnitus, so I had to have my daughter come and take a listen.  Yep, it is there.  One of the parameters that I changed in the VFD was the "carrier frequency" from 12kHz to 16khz, which helped ever so slightly, but not enough. If I lower that number below 10kHz the buzzing becomes prominent.
> 
> Would anyone have any thoughts on what else could be causing that, or is this just the way it is?  The motor on this mill is a 230v, 3ph, 8A, 1720rpm flavor, and the original motor I might add, which I would like for it to stay that way.  I am considering purchasing a different VFD but not sure if that would make any difference.  Would love to get a Durapulse from Automation Direct but it seems that they are perpetually out of stock.  I am considering a Teco or a Hitachi, but maybe that would not make any difference other than I could then say I have a "name brand."



Moving it up to 16khz is getting closer to the uper limits of your hearing so will sound a bit quieter , i personaly dropped my frequency setting down , which made the buzz much less anoying to me.

I might even have gone down to 1khz to 2khz range.

Stu


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## Karl_T (Jun 27, 2022)

FWIW, I have about eight VFDs in use. I put one on a motor on my apple packing line and could not quiet the whine. Had to remove the VFD.  Guess it seved its purpose, because I learned the correct speed for the output shaft and then made pulley changes to have it run correctly.

I then put the same VFD on a Wells mill with no issue.

Clueless as to why it would whine on one install and not on another.


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## 7milesup (Jun 27, 2022)

I just went out to the shop and changed the carrier frequency to 4.  Nope, not good.  Changed it back to 16.
Funny thing is that this mill is quiet enough that I can hear this buzz/whine.  My previous mill (PM833T) was so noisy with the geared head that had I converted that one to a VFD operation, I would have never been able to hear it.

I guess the question remains in my mind as to whether a different VFD would still have the whine.  I a different VFD would cure it, I would go that route.


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## tq60 (Jun 27, 2022)

The noise may be from things moving.

Motor a has just wires where motorb may be better supported where wires cannot move, or the way the windings are wound.

Open the end bell and look at the motor windings, many are tied with cord and coated.

Sent from my SM-G781V using Tapatalk


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## rabler (Jun 27, 2022)

Is the whine changing in pitch to match the carrier frequency?  Especially with an off brand VFD, I'm just wondering if you have something like a bad output transistor that is causing the VFD to ouput a messier signal than it should.  If you are, male, over 50 and have tinnitus, I'd be really surprised if you could hear 16kHz.  I guess it may be a lower frequency resonance in the motor.


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## wachuko (Jun 27, 2022)

We have different VFDs...I have the Telco L510, but the parameter that helped mine completely quiet down was the last one on this list...  Can you check yours and see if it has something similar?

Control Method -> Code: 00-00 -> From VF mode (0) to SLV mode (1)
Main Frequency Source Selection -> Code: 00-05 -> From Keypad (0) to Potentiometer on Keypad (1)
Frequency Upper Limit -> Code: 00-12 -> Set to 60.00Hz
Frequency Lower Limit -> Code: 00-13 -> Set to 10.00Hz
Acceleration Time -> Code: 00-14 -> Set to 5 seconds
Deceleration Time -> Code: 00-15 -> Set to 5 seconds
Carrier Frequency -> Code: 11-01 -> From 5 to 16 kHz
*Carrier Mode Selection -> Code: 11-02 -> From Mode1, 2-Phase PWM modulation (1) to Mode0 3-Phase PWM modulation (0)*


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## 7milesup (Jun 27, 2022)

rabler said:


> Is the whine changing in pitch to match the carrier frequency?


Yes, the noise becomes a lower frequency when lowering the carrier frequency.  
I am over 50 and have tinnitus but for some reason, I can 'sort of' hear this.  My daughter came out to the shop last night because I could not determine if it was coming from the VFD or the motor.  She confirmed it was from the motor.


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## 7milesup (Jun 27, 2022)

wachuko said:


> Carrier Mode Selection -> Code: 11-02 -> From Mode1, 2-Phase PWM modulation (1) to Mode0 3-Phase PWM modulation (0)


Unfortunately, mine does not have that option.


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## woodchucker (Jun 27, 2022)

mksj said:


> The reason for your auto-tune running shorter is because it is running it static as opposed to dynamic. The latter requires the motor to not be connected to a load so the motor can turn.


Can't he put the spindle in neutral to remove the load, and re-run?


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## mksj (Jun 27, 2022)

The motor needs to be completely disconnected from the drive system, the Reeves drive and belt would have both friction and and increase mass/momentum. The static mode does work well, so it is a good alternative if one cannot disconnect the drive. There are also other parameters that can tune the VFD to the system with the drive running, this is not motor specific but system specific. Different VFD's use different methods to adjust the carrier frequency so there can be some difference between brands, and it is also a function of the motor. If it is a high pitched whine, this is just a function of how VFD's operate and they all will exhibit it. My mill uses a TEBC, so the electric fan noise is the dominant noise, you can here some whine when it initially starts at the low Hz. As I mentioned, try to run the motor at a higher Hz like 80 and it should decrease.


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## woodchucker (Jun 27, 2022)

mksj said:


> The motor needs to be completely disconnected from the drive system, the Reeves drive and belt would have both friction and and increase mass/momentum. The static mode does work well, so it is a good alternative if one cannot disconnect the drive. There are also other parameters that can tune the VFD to the system with the drive running, this is not motor specific but system specific. Different VFD's use different methods to adjust the carrier frequency so there can be some difference between brands, and it is also a function of the motor. If it is a high pitched whine, this is just a function of how VFD's operate and they all will exhibit it. My mill uses a TEBC, so the electric fan noise is the dominant noise, you can here some whine when it initially starts at the low Hz. As I mentioned, try to run the motor at a higher Hz like 80 and it should decrease.


well his is not VFD noise, so could it be more serious by transmitting to the windings? Could it affect them, and cause them to fail?


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## mksj (Jun 27, 2022)

The whine is generated in the motor, not the VFD. If he does a video we can better determine the significance of the noise. Higher carrier frequency should cause less mechanical movement of the windings, but can cause increased heating. In general this is not an issue with newer motors. 








						VFD Carrier Frequency?
					

I'm in the process of switching my lathe over to 3phase / VFD power.  I got a 2hp Seimens motor on ebay for 99$ with free shipping,  and a Teco Westinghouse L510 VFD.     I've got the new motor mount fabricated and the motor installed.  I've drawn up a circuit diagram, based largely on the info...




					www.hobby-machinist.com


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## woodchucker (Jun 27, 2022)

mksj said:


> The whine is generated in the motor, not the VFD. If he does a video we can better determine the significance of the noise. Higher carrier frequency should cause less mechanical movement of the windings, but can cause increased heating. In general this is not an issue with newer motors.
> 
> 
> 
> ...


He said his daughter listened, and it was coming from the motor not the vfd.


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## Dabbler (Jun 27, 2022)

@7milesup I also have a Teco L510, and mine is very quiet.  One setting that can make more noise is an incorrectly set amperage value.  My motors are 6.3 amps, and when I originally set them to 6 mine buzzed as well.  I set mine to 6.9 it all went away.


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## 7milesup (Jun 27, 2022)

woodchucker said:


> He said his daughter listened, and it was coming from the motor not the vfd.


A motor can/will generate noise(s) due to a VFD.  I fly large electric RC airplanes and helis and the motors will generate different noises based on the settings.  In fact, the "beeps" that comes from the motors during setup and every time you plug the batteries in are coming from the motor, not the VFD (or ESC in that case).


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## rabler (Jun 27, 2022)

Dabbler said:


> @7milesup I also have a Teco L510, and mine is very quiet.  One setting that can make more noise is an incorrectly set amperage value.  My motors are 6.3 amps, and when I originally set them to 6 mine buzzed as well.  I set mine to 6.9 it all went away.


I'd guess more amperage would change the PWM output.  Makes me wonder if tuning the DC voltage level could also have some impact that might reduce the noise at the lower amperage setting.  Purely academic curiosity here.


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## woodchucker (Jun 27, 2022)

7milesup said:


> A motor can/will generate noise(s) due to a VFD.  I fly large electric RC airplanes and helis and the motors will generate different noises based on the settings.  In fact, the "beeps" that comes from the motors during setup and every time you plug the batteries in are coming from the motor, not the VFD (or ESC in that case).


oh, I agree with you. I think mksj either missed that, or was discounting it. I worry that it might not be good for the motor if it vibrates the windings. electro magnetics cause wire fluctuations.. some motors can handle it, some cannot.


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## 7milesup (Jun 27, 2022)

Ok, here are 3 videos.  I will be curious if you can hear anything at all.  When I was doing this my middle daughter came out to the shop to see what was going on.  When I turned the mill on she made this face of "what the heck is that!?"  She said that the buzzing was very apparent.  Unfortunately, my tinnitus has been really bad lately, due to stress.  If I am sick or stressed out my hearing issues become prominent.


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## mksj (Jun 27, 2022)

I did indicate that the VFD noise is from the motor. The motor VFD whine is normal in the last video, although a bit louder than I would expect at 16 kHz. If it doesn't bother you, I wouldn't run out and replace the VFD. As I mentioned, higher end VFD's may use different PWM algorithms and/or variable frequencies.








						Reducing Audible Noise in VFD Applications
					

This article gives an overview of audible noise in VFD Applications and provides 4 steps on how to reduce audible noise in the system.




					www.kebamerica.com


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## stupoty (Jun 27, 2022)

rabler said:


> Is the whine changing in pitch to match the carrier frequency?  Especially with an off brand VFD, I'm just wondering if you have something like a bad output transistor that is causing the VFD to ouput a messier signal than it should.  If you are, male, over 50 and have tinnitus, I'd be really surprised if you could hear 16kHz.  I guess it may be a lower frequency resonance in the motor.



You could be hearing a harmonic of the frequency, as @tq60 said the windings are probably resonating with the carrier frequency.

Stu


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## 7milesup (Jun 27, 2022)

So is 16kHz the maximum on most (or all) VFD's?  I am now understanding that there is a balance between carrier frequency, noise and possible longevity of the motor.


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## Dabbler (Jun 27, 2022)

The higher the PWM frequency, the more energy is dissipated in the IGBT modules.  Never too much of a problem, though.  You need to pick a frequency that minimizes that whine, not just for esthetic reasons.  as @woodchucker is suggesting, it can be a little harder on the windings to vibrate them at these frequencies.

A reactive output filter (a torroid inductor) on each of the phases can help to minimize these sounds/vibrations.  You choose the size based on the running current and maximum current.  For Teco L510 I go to Westing house ans specify that my max running amps is 7, and that my typical in use amperage is about 3, and they specified my inductors for me.  worked fine.


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## macardoso (Jun 27, 2022)

7milesup said:


> So is 16kHz the maximum on most (or all) VFD's?  I am now understanding that there is a balance between carrier frequency, noise and possible longevity of the motor.


The carrier frequency primarily only affects heating. This is because the IGBT's (transistor outputs from the drive) have extremely low resistance when fully turned ON, but have some significant resistance as they momentarily switch from ON/OFF. Each time the transistor switches, a small pulse of extra heat is dissipated. The more times the transistors switch per second (the carrier frequency) the more heat is generated in the drive output. 

A similar phenomenon occurs at the motor due to eddy current breakdown losses, but it plays a lesser effect.


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## rabler (Jun 27, 2022)

stupoty said:


> You could be hearing a harmonic of the frequency, as @tq60 said the windings are probably resonating with the carrier frequency.
> 
> Stu


I believe  technically a harmonic is a higher frequency component.  Not sure what you'd call a lower frequency, a sub-harmonic?  (lol).  But that's what I was pointing toward with a "lower frequency resonance".


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## 7milesup (Jun 27, 2022)

Dabbler said:


> A reactive output filter (a torroid inductor) on each of the phases can help to minimize these sounds/vibrations. You choose the size based on the running current and maximum current. For Teco L510 I go to Westing house ans specify that my max running amps is 7, and that my typical in use amperage is about 3, and they specified my inductors for me.


Wow, those puppies are expensive.

Edit:  Well, they can be expensive but found some for a reasonable price. 








						Line/Load Reactor, 3 Phase, 12A, 1.25mH, 208/240V,
					

Line/Load Reactor, 3 Phase, 12A, 1.25mH, 208/240V, Open, 2 to 3hp, 3% Impedance, See Specification Sheet, This Item is Part of the Power Quality Express Stocking Program




					www.wolfautomation.com
				












						Line Reactor, 3 Phase, 12A, 208/240V @ 3hp, 3% Low
					

Line Reactor, 3 Phase, 12A, 208/240V @ 3hp, 3% Low-Z Impedance, Open




					www.wolfautomation.com
				




@Dabbler  So these just mount to the output side of the VFD within my enclosure?

I am at a little bit of a dilemma here.   Do I spend some money on a higher end VFD (WEG or TECO for example) with the hope that it solves it, or keep my existing VFD and buy a line reactor and hope that solves the issue.  If I go up to 80Hz the noise goes away, I think. I will have to have my daughter check it out later. I'm sure you guys are wondering why I'm worried about this with my tinnitus but it actually seems to make my tinnitus worse with this noise.


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## mksj (Jun 27, 2022)

Line and load filters are not dV/dT filters and the primary purpose of a dV/dT filter is to tame voltage spikes associated with longer motor cable runs and reflections that occur in the wire. Line reactors help decrease the current draw into the VFD and decrease electrical noise, load help tame the heating effects and insulation damage that can occur. I prefer to use a DC choke as opposed to an input line reactor, these would have no effect on the high frequency whine. In addition the filters are dV/dT often designed not to be used with carrier frequencies above 8 kHz, and there are also limitations as to the variable frequency range that they can be used. The TCI output filters information is attached. 

The KEB link clearly states "It should also be noted that audible noise varies between VFD manufacturers. So even though the switching frequencies are the same, one still might be audibly louder. For example, I have heard some competitor drives that are set to “16kHz” that still produce quite a bit of sound. I suspect there is more to the audible noise than just the rate of IGBT switching. I suspect the quality of the PWM signal and the driver circuitry also plays a big part. These details cannot be found in datasheets and are only found by testing side-by-side".


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## rabler (Jun 27, 2022)

I can hear the whine on your 16kHz video, which makes me suspect it is not a 16kHz noise.  I've been tested for hearing loss, and know I don't have good hear up at those frequencies.  (And yes I do have tinnitus too).   Be interesting to put an oscilloscope on there, especially one with some frequency analysis capability.  But that type of equipment is not sitting around in your typical hobby shop.  While carrier frequency noise is one component, a VFD uses some complicated control algorithms that could also have some periodic effects, possibly even creating beat frequencies that interact with the carrier.

Myself, I'd go with trying a different brand VFD.  That noise would drive me nuts.  Oh, wait, maybe it's too late already ...


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## Dabbler (Jun 27, 2022)

@7milesup if running your current VFD at 80 Hz limits the noise, and your mill works fine, I say go for it.  You can always do other remedial actions later.

@mksj I only used a line reactor at GE support insistence - and it did the right things for my motor noise at 10 KHz modulation freq.  I agree that other solutions would seem more logical, but this is my experience.  I have a 2HP pancake motor with a slightly larger inductance than my other 3PH 2HP motors, and this ?might? be a factor.

(Actually they called it a line filter, but the part they had me order called it a 'line reactor' - go figure....)


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## stupoty (Jun 27, 2022)

rabler said:


> I believe  technically a harmonic is a higher frequency component.  Not sure what you'd call a lower frequency, a sub-harmonic?  (lol).  But that's what I was pointing toward with a "lower frequency resonance".


Good point , maybe they would be a combination of multiple harmonics causing beat interference which may be at a lower frequency than the original ?

or it may be as you say a "sub harmonic" or undertone series. https://en.wikipedia.org/wiki/Undertone_series


Stu


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## rabler (Jun 27, 2022)

Dabbler said:


> (Actually they called it a line filter, but the part they had me order called it a 'line reactor' - go figure....)


My take is those terms are 80% marketing (we need a new name to make our product sound special), and 20% technological.  Reactance is the EE term for the capacitive/inductive component of impedance.  dv/dt is from calculus, related to the mathematics used to analyze those components. So the engineers used capacitors and inductors, to make a specific filter, and the product marketing guys gave it a product line name.  And the names get thrown around sort of generically and meanings don't rigidly hold true.


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## slow-poke (Jun 27, 2022)

have you tried default settings other than current?

I’m wondering if the auto tune has enabled a wonky settin?

I have two VFDs, both used from eBay, both more or less silent. One is a brand name the other a cheap made in China, paid about $50 for each one.  Both work about the same. I would try another VFD.


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## Jeff.64 (Jun 27, 2022)

Maybe this will help with determining the frequency without a scope.
Test Tones: https://www.youtube.com/channel/UCgTxhjNGWS8EX-i9XMNKKQw/videos
How Old Are Your Ears: 




Line reactor, AutomationDirect (I've used a lot of their stuff over the last 14 years or so without issue): https://tinyurl.com/25e52cox
Won't be in stock until 06/30/2022.

I would be surprised if a line reactor removed the mechanical noise.  The other posters are correct in that long cables require line reactors on the motor side due to the large voltage spikes that can sometime occur and to prevent harmonics from being dumped onto the supply line when used on the drive input.  Years ago, using F class or better field insulation on regular motors prevented voltage spikes from "poking" holes in the insulation.  Of course they would still sing.  DIdn't have PWM freqencies as high as they are today.  Back in the 90's, AllenBradley Vector drives (new hotness better than plain old V/Hz) had a max of 8 Khz if I remember right.  Newer VFD rated motors are both electrically and mechanically designed to be used with VFD's.  On the other hand I you're going to use the mill 1 hour per week, who knows, the motor might outlast you if you can deal with the noise somehow.

Magnetostriction contributions due to motor not designed to be used with a VFD?
Maybe try a different motor.  Here are some possibly helpful articles.



			https://onlinelibrary.wiley.com/doi/abs/10.1002/eej.10338
		





__





						How to Stop VFDs From Ruining Your Motors | VFDs.com
					






					vfds.com
				







__





						Variable Frequency Drive Motor Mechanical Vibration
					





					www.variablefrequencydrive.org
				











						Motors For Use With VFDs
					

The questions can pile up quickly when it’s time to specify a motor to pair with a variable drive.




					www.esmagazine.com
				







__





						Reactors for VFDs
					






					www.electram.com
				




I'm 59 and I can't hear anything above 12 kHz.  I can clearly hear the sound in all three of your videos.

Hope This Helps,
Jeff


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## stupoty (Jun 27, 2022)

Jeff.64 said:


> Maybe this will help with determining the frequency without a scope.
> Test Tones: https://www.youtube.com/channel/UCgTxhjNGWS8EX-i9XMNKKQw/videos
> How Old Are Your Ears:
> 
> ...




If you need quite good audio analyses tool for free (also sound editing) I highly recommend the open source "Audacity".
Cross platform too (windows / mac / linux) , https://www.audacityteam.org/

Here are two screen shoots , one of a spectrogram (waterfall) plot of the sound file and the other a frequency plot of a small time segment.

You can see the energy at different frequencies quite easily on the spectogram type plot very intuitively, the frequency plot shows a big spike at about 12.5khz but other strong frequencies are a little harder to spot I would say with this type of plot.

Interestingly the audio file contains nothing above 16khz , a lot of microphones produce hideous sound above this frequency also most people can't hear any of it and it saves the compression algorithm from wasting bandwidth on it.  So best to just filter it out with a low pass filter (most likely reason it's missing).

Stu


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## stupoty (Jun 27, 2022)

Jeff.64 said:


> Maybe this will help with determining the frequency without a scope.
> Test Tones: https://www.youtube.com/channel/UCgTxhjNGWS8EX-i9XMNKKQw/videos
> How Old Are Your Ears:
> 
> ...



interestingly , I notice on the sound tone video their is also nothing above 16khz so I think it's youtube doing a low pass filter.




Stu

edit , you can generate tones with audacity too.


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## 7milesup (Jun 27, 2022)

rabler said:


> That noise would drive me nuts. Oh, wait, maybe it's too late already .


My wife and kids think I am nuts in more ways than one.  
All of my kids can hear it (oddly, all three of my adult daughters have been out in the shop over the last day or so).

I think it is time to try a WEG from Automation Direct.  


			https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/micro/cfw300b10p0b2db20


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## 7milesup (Jun 27, 2022)

stupoty said:


> interestingly , I notice on the sound tone video their is also nothing above 16khz so I think it's youtube doing a low pass filter.
> 
> View attachment 411854
> 
> ...


I didn't realize that those graphs were of MY videos.  Very interesting.


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## Jeff.64 (Jun 27, 2022)

stupoty said:


> interestingly , I notice on the sound tone video their is also nothing above 16khz so I think it's youtube doing a low pass filter.
> 
> View attachment 411854
> 
> ...


Thanks for the link.  Several years ago, I downloaded some similar Youtube files and determined that my hearing sensitivity stopped at 14 kHz.  So maybe my hearing range was limited by YouTube... interesting.  I posted the link to be used as a quick and dirty method to determine if the fundamental frequency of the motor was 16 kHz.  That is, you could compare the tone of the motor to the YouTube videos.  I wonder if an external microphone with a flat enough response is available for use with a cellphone, and if so, is a cellphone DSP good enough to supply a spectrum analyzer app to see what the fundamental motor frequency and harmonic amplitudes are.  I've seen people use the accelerometer chip in their cellphones with an app to make some vibration plots in x, y and z.  Might be a gimmick that could only tell you which axis has the greatest amplitude. Granted it's no IRD.  Often thought about rolling my own as even used ones (Radwell) were out of my price range for hobby use.  Maybe there are some antique IRD's on Ebay by now... Just checked.  I think I'll wait a little longer.  Yeah, I know, a little long winded.


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## stupoty (Jun 27, 2022)

Jeff.64 said:


> Thanks for the link.  Several years ago, I downloaded some similar Youtube files and determined that my hearing sensitivity stopped at 14 kHz.  So maybe my hearing range was limited by YouTube... interesting.  I posted the link to be used as a quick and dirty method to determine if the fundamental frequency of the motor was 16 kHz.  That is, you could compare the tone of the motor to the YouTube videos.  I wonder if an external microphone with a flat enough response is available for use with a cellphone, and if so, is a cellphone DSP good enough to supply a spectrum analyzer app to see what the fundamental motor frequency and harmonic amplitudes are.  I've seen people use the accelerometer chip in their cellphones with an app to make some vibration plots in x, y and z.  Might be a gimmick that could only tell you which axis has the greatest amplitude. Granted it's no IRD.  Often thought about rolling my own as even used ones (Radwell) were out of my price range for hobby use.  Maybe there are some antique IRD's on Ebay by now... Just checked.  I think I'll wait a little longer.  Yeah, I know, a little long winded.



View attachment 16khz.mp3


One 16khz test tone, ear safety first , don't have your sound tooo high, turn the volume up whilst it's playing or look out for young'uns clutching there ears in pain 


I've had quite good success with phone based spectrum analysers for basic investigation of frequency there are a few free to download in the play store / app store.  I just checked the one on my phone , it clearly "sees" (hears) the 16khz tone.

Stu


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## mksj (Jun 27, 2022)

You will find that many lathes and mills use the Yaskawa drives, including the factory Sharp mills. There are various models, typically the V1000 is used, but it has been updated to the GA500 and GA700 models. Both models have worked very well. Alternative is the Hitachi WJ200-022SF or the Teco E510. In this case it is hard to tell what the issue is, but so far when I encounter tuning/motor issues like this it is typically the VFD is a poor match for the motor. It may also be that the VFD circuitry may not supporting the higher switching frequency, I read elsewhere that going from 8khz to a 16khz requires almost double the cost in components. Putting on bad-aids to try to fix a poor VFD is not a good solution. The mill motor is not that old and should not have the issues seen with older mill motors. I use the Yaskawa VFD's in both my lathe and mill, carrier frequency is 12kHz and I do not hear it at 60 Hz.

GA50UB012ABA - 3 HP, 12 Amps, Normal Duty, 3 HP, 11 Amps, 240 VAC, Heavy Duty, Single-Phase, IP20/Protected Chassis 








						GA50UB012ABA - 3 HP, 12 Amps, Normal Duty, 3 HP, 11 Amps, 240 VAC, Heavy Duty, Single-Phase, IP20/Protected Chassis
					

Yaskawa - GA500 AC Microdrive - GA50UB001ABA - 1/16 HP, 1.2 Amps, Normal Duty, .17 HP, 0.8 Amps, 240 VAC, Single-Phase, IP20/Protected Chassis



					control-concepts.myshopify.com
				



Hitachi  WJ200-022SF








						VFD, 3hp, 200V, Single Phase, Sensorless Vector, I
					

VFD, 3hp, 200V, Single Phase, Sensorless Vector, IP20, High Starting Torque




					www.wolfautomation.com
				



Teco Westinghouse E510-203-H-U








						VFD, 3hp, 10.5A CT/VT,230VAC, Single and 3 Phase,
					

VFD, 3hp, 10.5A CT/VT,230VAC, Single and 3 Phase, F2, 7.39x5.07x6", Med. Duty Compact, NEMA1/IP20




					www.wolfautomation.com


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## 7milesup (Jun 29, 2022)

I replaced the Lapond VFD with a WEG from Automation Direct. *WEG CFW300 VFD* 
I did a quick basic wiring job on the WEG and got the mill running (no remotes programmed in yet).  At first, I thought it sound just as bad or worse than the Lapond but then realized that the default carrier frequency is 5kHz.  I increased it to 15kHz and the buzzing seems to have gone away and is running rather smooth.  Need to do some fine-tuning yet but I think this VFD is a keeper.

Now I have to figure out why there is some drivetrain noise.  My inclination is that it might be coming from the power drawbar shaft, but need to examine it further.


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## wachuko (Jun 30, 2022)

Man, I don't trust your hearing... get your daughter to confirm!

Joking, joking...

Glad that got resolved!  Once my VFD was running the motor quietly,  it became clear that the bearings in the pulley were shot... lol...


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## Jeff.64 (Jul 2, 2022)

Glad to hear the drive was the culprit as opposed to the motor.  I think a different motor would look ugly in place of that good looking OEM motor currently on your mill.   
From what I can see in your videos, the motor looks like it was custom made for the mill.
Have a happy and safe 4th.


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## 7milesup (Jul 2, 2022)

I was just out there Jeff messing around with it and I thought "this mill sure runs smooth and quiet!"

Now I need to figure out this ancient and archaic CNC portion of it.


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