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load reactor causes more motor noise

M

MeanMachine1980

Aluminum
Joined
Dec 30, 2017
Im in the middle of rebuilding a southbend lathe. I purchased a new invertor class 3 phase, 2hp motor. I also purchased a hitachi wj200 3hp VFD. I have been trying to find out a way to quiet the loud pitched whine that you hear caused by the pwm. I read everywhere and was told that a load reactor would quiet the system down. I purchased a load reactor and it makes the noise worse.....
I have everything grounded good and am using good "VFD" cable that is double shielded.

any suggestions?

Thanks
 
MeanMachine1980 said:
Im in the middle of rebuilding a southbend lathe. I purchased a new invertor class 3 phase, 2hp motor. I also purchased a hitachi wj200 3hp VFD. I have been trying to find out a way to quiet the loud pitched whine that you hear caused by the pwm. I read everywhere and was told that a load reactor would quiet the system down. I purchased a load reactor and it makes the noise worse.....
I have everything grounded good and am using good "VFD" cable that is double shielded.

any suggestions?

Thanks
Click to expand...

Does the load reactor exactly match whatever Hitachi specified for that drive and load conditions? Hitachi SKU number mayhap?

Has the noise "migrated into" the reactor as most obvious emitter?

There are usually more choices than one, but it is the maker who has the best recommendation, if only because they are the ones who have tested them the most thoroughly.

The math is not terribly complex. Gathering the proper data to apply it to can be.

And.. have you created a "Ground loop" or a feedback path that has the VFD amplifying its own noise or attempting to sustain oscillation, perchance?

Oscilloscope shows what, and where?
 
Have you read the manual..the carrier frequency is programmable between 2khz and 15khz. One of those should kill the audible.

You should not need a load reactor at all.

Stuart
 
atomarc said:
Have you read the manual..the carrier frequency is programmable between 2khz and 15khz. One of those should kill the audible.

You should not need a load reactor at all.

Stuart
Click to expand...

That whole range falls within the normal human audio band.

Nail 6600 Hz, and I've got an 85 dB down "notch" loss. 175 mm Gun, 101st ABN Div Arty initiated, Tet '68.

That VFD would be TOTALLY soundless, just like MOPAR caravan disk brake wear warning squeelers and London Transport tire choices on Leyland Titan double-decker buses are. Gun was firing outgoing. Damned double-deckers and brakes, OTOH have twice each tried to kill my deaf ass.

Maybe the OP simply still has undamaged hearing?

Or he did until he bought a VFD, anyway...

:)
 
MeanMachine1980 said:
Im in the middle of rebuilding a southbend lathe. I purchased a new invertor class 3 phase, 2hp motor. I also purchased a hitachi wj200 3hp VFD. I have been trying to find out a way to quiet the loud pitched whine that you hear caused by the pwm. I read everywhere and was told that a load reactor would quiet the system down. I purchased a load reactor and it makes the noise worse.....
I have everything grounded good and am using good "VFD" cable that is double shielded.

any suggestions?

Thanks
Click to expand...



what do you have the "carrier" frequency set to?

Can you describe the noise... is it a whistleable frequency/pitch? Higher than that? Is it a noise as high pitched as you could hear from an old TV?

The reactor itself might make as much noise as the motor did, as mentioned.... you sure that is not happening?

Cable shielding is not important to this matter, Grounding "could be" important but likely has nothing to do with it.

Set the carrier to the highest frequency and see what happens.... does it change the noise, or not?
 
thermite said:
Does the load reactor exactly match whatever Hitachi specified for that drive and load conditions? Hitachi SKU number mayhap?

Has the noise "migrated into" the reactor as most obvious emitter?

There are usually more choices than one, but it is the maker who has the best recommendation, if only because they are the ones who have tested them the most thoroughly.

The math is not terribly complex. Gathering the proper data to apply it to can be.

And.. have you created a "Ground loop" or a feedback path that has the VFD amplifying its own noise or attempting to sustain oscillation, perchance?

Oscilloscope shows what, and where?
Click to expand...

Hello Thermite

Thanks for the reply. I purchased a 5% impedance but Ill have to double check because it looks like the 3% impedance one. I have a 2hp motor and a 3hp rated vfd. The load reactor I bought was rated for 2hp, dont know if this matters or not? I contacted Hitachi to see what they have to say, still waiting. The reactor makes a little noise but there is noticeably more noise at the motor with the reactor hooked up.
I have the motor cable grounded to the case of the motor, the cable is then grounded to the VFD and from there to the 220v single phase outlet. The reactor has no grounding lug. The rector is groudned in the electrical cabinet it is in though.

When I wired it up for an initial test with un shielded cable going from the VFD to the motor with no reactor it was quieter than after I used high quality cable and a reactor??
 
You can kill the noise made by the motor by connecting delta connected (And Only delta connected) capacitors at the motor: the reactor goes between the vfd and the motor. 3, 10uF capacitors is good enough for your application. they draw a little bit of current but the motor is lagging power factor anyway so most of it cancels out.


I would set the pwm frequency to at least 4Khz. the capacitors will ensure you have a sine wave from phase to phase, but you do not have a sine wave from phase to ground.. in fact you have a + 170v, - 170v square wave at the pwm frequency. if there is something wrong with the motor that common mode voltage could be causing noise.

the 3 leg line load reactors do not have any common mode inductance so adding it will not change much of anything to the common mode voltage problem, if such a problem exists.


to anyone else reading this: the resonant frequency of the line/load reactor and the delta connected capacitors needs to be lower than the pwm frequency of the drive. in this case, the load reactor is probably 3mh and the 10uf capacitors are just fine. I found that for my .2KW rated vfd, a 9mH choke and 2uf delta capacitors was sufficient, and the added ripple current drawn by the capacitors was Negligible from the VFD's perspective at 4Khz.

obviously you want a line/load reactor.. reactors rated "line" only will probably have much thicker laminations and not do as well filtering the pwm frequency though they will still work, just run hotter.
 
MeanMachine1980 said:
Hello Thermite

Thanks for the reply. I purchased a 5% impedance but Ill have to double check because it looks like the 3% impedance one. I have a 2hp motor and a 3hp rated vfd. The load reactor I bought was rated for 2hp, dont know if this matters or not? I contacted Hitachi to see what they have to say, still waiting. The reactor makes a little noise but there is noticeably more noise at the motor with the reactor hooked up.
I have the motor cable grounded to the case of the motor, the cable is then grounded to the VFD and from there to the 220v single phase outlet. The reactor has no grounding lug. The rector is groudned in the electrical cabinet it is in though.

When I wired it up for an initial test with un shielded cable going from the VFD to the motor with no reactor it was quieter than after I used high quality cable and a reactor??
Click to expand...

You are posting from a computing device of some sort.

Odds-are it has multimediddleyah audio software/app, and a microphone. The noise YOU can hear is in the audio/music passband.

Try recording it, acoustically.

If your software has graphical display tools - as most do - you can even look at the captured waveform on screen and in eye-candy colours to see where the spectral distribution, eg: energy peaks are.

And even post that "capture" as a foto, right here on PM!

Audio band = no pressing need to buy a 'scope.

Wiring-wise, it seems as if you HAVE created a ground or feedback loop.

Try UNdoing - selectively - the bonding and grounding you added until the culprit stows its noisy head.

Your reactor? It might stay. Or it may be re-purposed to an interesting looking - albeit clumsy.........

paperweight.

Too many sharpish edges for a decent doorstop.

:)
 
MeanMachine1980 said:
I also purchased a hitachi wj200 3hp VFD. I have been trying to find out a way to quiet the loud pitched whine that you hear caused by the pwm. I read everywhere and was told that a load reactor would quiet the system down. I purchased a load reactor and it makes the noise worse.....
Click to expand...

Is this your first VFD?

Did you set drive parameters yourself or auto-tune?

Where did the load reactor come from? From a indexed table published by Hitachi?

What is the part number?
 
The noise is your switching frequency, find the setting in your manual and change it to be less annoying. Higher switching frequencies do derate the drive though with a 3hp on a 2hp load you won't have a problem.
 
JST said:
what do you have the "carrier" frequency set to?

Can you describe the noise... is it a whistleable frequency/pitch? Higher than that? Is it a noise as high pitched as you could hear from an old TV?

The reactor itself might make as much noise as the motor did, as mentioned.... you sure that is not happening?

Cable shielding is not important to this matter, Grounding "could be" important but likely has nothing to do with it.

Set the carrier to the highest frequency and see what happens.... does it change the noise, or not?
Click to expand...

I know about setting the carrier to a higher setting should minimize the whine but I tried it at the max 15khz and still the noise exists. It is of course more noticeable when the lathe is slowing down or when I lower the speed with the potentiometer. The reactor does make some noise I know this because I disconnected it to see if the noise changed. To my surprise after I disconnected it the motor didnt make as much noise and the reactor didnt make any noise obviously..
The noise Im talking about is the high pitched whine that is associated with the PWM, Ive never heard a vfd driven motor without it. Every video on youtube Ive watched with a vfd has it. I was hoping a reactor would fix it but it made it worse.
 
MeanMachine1980 said:
the high pitched whine that is associated with the PWM, Ive never heard a vfd driven motor without it. Every video on youtube Ive watched with a vfd has it.
Click to expand...

"Never"? "Every"? Even on Y-T?

Perhaps I wasn't far off on hearing then.

Seems most of us cannot hear as well as you seem to do.

Seriously. I can remember having the family trait of "bat ears". Of being able to slip into an Appalachian forest and just vanish. Walk right up to animals from their downwind side. Go clear off-scale on Radioear's best Bruel & Jahr instruments in an anechoic test chamber...

Remember. Only.

Make us a video. Some here may not even hear YOUR rig.

Meanwhile.. protective headgear. MSA as a minimum, Bose or the like better yet.

Hearing really is that good, it can save your life. Well worth protecting.
 
MeanMachine1980 said:
This is my first VFD
Click to expand...
Ah, well then.

As with a woman, you'll find the noise easier to deal with if they are in another room.

Nice thing about a VFD is they are way less complex, won't whine about where you left the toilet seat or nag about your bad habits, and you don't really have to share a blanket with 'em.

How much spare wire yah got left? Sound attenuates with the square of distance IIRC. Other side of a wall helps, too.

:)
 
johansen said:
You can kill the noise made by the motor by connecting delta connected (And Only delta connected) capacitors at the motor: the reactor goes between the vfd and the motor. 3, 10uF capacitors is good enough for your application. they draw a little bit of current but the motor is lagging power factor anyway so most of it cancels out.


I would set the pwm frequency to at least 4Khz. the capacitors will ensure you have a sine wave from phase to phase, but you do not have a sine wave from phase to ground.. in fact you have a + 170v, - 170v square wave at the pwm frequency. if there is something wrong with the motor that common mode voltage could be causing noise.

the 3 leg line load reactors do not have any common mode inductance so adding it will not change much of anything to the common mode voltage problem, if such a problem exists.


to anyone else reading this: the resonant frequency of the line/load reactor and the delta connected capacitors needs to be lower than the pwm frequency of the drive. in this case, the load reactor is probably 3mh and the 10uf capacitors are just fine. I found that for my .2KW rated vfd, a 9mH choke and 2uf delta capacitors was sufficient, and the added ripple current drawn by the capacitors was Negligible from the VFD's perspective at 4Khz.

obviously you want a line/load reactor.. reactors rated "line" only will probably have much thicker laminations and not do as well filtering the pwm frequency though they will still work, just run hotter.
Click to expand...

I have heard of the delta connected capacitors but have never seen it wired up. Do you know where I can find something. Does one make a small box with the capacitor arrangement and then wire your motor and vfd to this box?
 
thermite said:
Ah, well then.

As with a woman, you'll find the noise easier to deal with if they are in another room.

Nice thing about a VFD is they are way less complex, won't whine about where you left the toilet seat or nag about your bad habits, and you don't really have to share a blanket with 'em.

How much spare wire yah got left? Sound attenuates with the square of distance IIRC. Other side of a wall helps, too.

:)
Click to expand...

The majority of the noise is coming from my motor. so moving the electrical box further away wouldnt be that helpful. Plus this is in my garage which only has 1 room.
 
If you have set the carrier frequency to 15kHz and you have run the autotune, then there is not much more that can be done programming wise to decrease the high frequency motor whine. The VFD output line reactor, may or may not help and it may also be a function of the motor/type. The line reactor is appropriately sized for this motor. I have installed 100's of the Hitachi's, the 015 and 022 models are not derated for the higher carrier frequency, most people do not notice the noise except when using the VFD below about 20Hz. It is something one lives with as the machine is often noisier then the whine. My only other suggestion would to be to try a heavier cast iron inverter motor, I often use the Marathon Black/Blue Max TENV or Baldor IDNM motors with good success. You can also change the drive ratios so the motor operates in the the 30-120Hz range or higher which would make the whine almost not audible.
 
MeanMachine1980 said:
The majority of the noise is coming from my motor. so moving the electrical box further away wouldnt be that helpful. Plus this is in my garage which only has 1 room.
Click to expand...

"I hear yah".. side effect of partially-trashed hearing is that some sounds are MORE annoying than they once were.

What's to love about RPC is clean sine-waves... and how indifferent they are even if kicked outdoors into a dog-house clear the other side of the building lot and several walls.

Even so... industrial goods, hobby size on up, are just NOT silent critters. There are Hardinge lathe models practically legendary for their incredibly low-noise, but still.. that is noticed BECAUSE it is so very rare.

I really do think you will need to get used to wearing high-tech "earmuffs".

Not kidding about. As with safety glasses, they are a good idea anyway.

Here's a trick I used to use. Didn't want to be UNAWARE of sounds around me, just not overwhelmed or unduly annoyed by them.

I'd wear the David Clark's I used for flying.

The boom mic went to a tiny intercom box atop the headband. Mic and amplifier picked up ambient sounds, but hard-limited their max volume.

Looked odd, but nothing noisy sneaked up on you, and normal conversations were easy, even with high background noise.

Fast-forward 25 years and there are LOTS of better solutions out there.
 
MeanMachine1980 said:
This is my first VFD
I set the motor amps in the initial set up of the VFD
I bought the line/load reactor from factory mation
KDRULA26H
Click to expand...

Cable length from VFD output terminals to reactor?
Cable length from reactor to target motor?
Reactor wires properly sequenced?
Nameplate of motor?
Might be time for some pictures.

Remove the reactor and use a short cable from VFD to motor. Unload the motor (remove any belts and let the motor free run)
You don't have to cut up your existing shielded cable. Just use scrap wire.
Then reset the drive and perform the auto-tune procedure. Test with carrier frequency steps of 1K, use 5K, 6k, 7k,... 12K.

Then report results.
 
mksj said:
If you have set the carrier frequency to 15kHz and you have run the autotune, then there is not much more that can be done programming wise to decrease the high frequency motor whine. The VFD output line reactor, may or may not help and it may also be a function of the motor/type. The line reactor is appropriately sized for this motor. I have installed 100's of the Hitachi's, the 015 and 022 models are not derated for the higher carrier frequency, most people do not notice the noise except when using the VFD below about 20Hz. It is something one lives with as the machine is often noisier then the whine. My only other suggestion would to be to try a heavier cast iron inverter motor, I often use the Marathon Black/Blue Max TENV or Baldor IDNM motors with good success. You can also change the drive ratios so the motor operates in the the 30-120Hz range or higher which would make the whine almost not audible.
Click to expand...

Interesting fact that the drive in question does not switch nearly that high. :Yawn:
 
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