VFD with 3 ph motor noise

K

Ken H>

Joined
Dec 31, 2011
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Hello all - this is something I've read other posts on, just not found them with searching. Seems like TimGunn had some good ideas? Anyway, The existing Ironhorse 2 hp, 3 ph, 3500 rpm motor I've been using for several years started giving error codes on a Huanyang Model #HY03D023B VFD. The error code indicated acceleration over current, or something wrong with motor. There had been a light rattle sound for several months which made me think bearing going bad. The grinder would run for 10 minutes, and sometimes only a minute or so. I ordered a new Ironhorse 2hp 3 ph 3500 rpm motor as replacement. Now runs without error codes - so far anyway. The problem is the "knocking" sound at low rpm, 300 to 900 rpm it can be pretty loud, by 1500 rpm not so loud, and by 2000 rpm it's almost not heard at all.

This is the same VFD I've been using for several years and been so happy with how smooth the motor ran, from 300 rpm to 3890 rpm (over speed a bit). Do I have a bad motor? OR, is it a setting in VFD? Here's a 40 second video showing the sounds and motor. The display on VFD isn't very clear at all, and the image is reversed for some reason and I've not yet found how to flip it.

 
The video runs fine for me. It's difficult to say but I'll take a wild stab and say either your fan is rubbing, or you have a motor bearing going out. Probably the latter
 
If a fan why would it not make a noise at all RPM? Remember i/ is brand new motor. It really seems like the RPM is not as smooth when it is making noise.

Grasping at ideas here.
 
Ken H> said:
If a fan why would it not make a noise at all RPM? Remember i/ is brand new motor. It really seems like the RPM is not as smooth when it is making noise.

Grasping at ideas here.
Click to expand...
I've had fans that make noise at higher RPM's but not lower. Has to do with torque mostly. The higher the speed the more torque on the fan. If it's out of balance just a bit it could be enough for it to rub.
It's easy enough to check if it's the fan. The housing comes off fairly easily and if it is rubbing you'll see it either on the housing or the fan or both.
 
Tim would be the guy to explain it, but I have noticed what I call "Cogging" at low speeds with a VFD. I think it is sort of a braking effect that makes the sound. The motor needs a certain amount of flywheel effect to run smoothly, and when it gets below a certain point it can't match the magnetic pull between the windings and the armature correctly.
 
Yep, that's what I was thinking also - Cogging. I'd forgot what it was called. Isn't there some settings in a VFD to prevent this problem? I remember sometimes there can be a vibration at certain RPM, and the VFD can be set to skip those RPMs so it's not an issue. This one is such a wide band of rpm (freqs) that's not a viable solution. I find it interesting the old motor didn't have this problem while the new motor does have this problem - all with the same VFD.

With the word "Cogging" I was able to find more info - seems like it can be caused by harmonics caused by the stator winding, of which the VFD has plenty. Seems like there was a suggestion to set a parameter that moves the freq around to help prevent those issues. Then I read "the current source inverter (CSI) and voltage source inverter (VSI) designs most often result in cogging, while the pulse-width modulated (PWM) type does not." The drives we use are PWM type.
 
I know that you can often remove the “cogging” noise from the kbac vfds by setting the torque jumper to variable instead of constant. Unfortunately, you lose all of your low end torque, but it’s a good troubleshooting tool to rule out the source of the noise.
If that’s a huanyang vfd, I think you can change pd175 from 0-1 to try variable torque and see if the noise changes.
 
Yea, it's a Huanyang Model #HY03D023B VFD, but I only see 35 or so parameters in the settings. Seems like there was a way to get to advanced settings for the parameter you're talking about but I've forgot how to do it, and don't find it in the manual I have. The paper manual I have doesn't list my model. I'm going to look at the original motor, take apart to check bearings, etc.
 
I just got off phone with AutomationDirect tech support. The tech said he was not familiar with that type of problem, but since I've tried 2 different VFD drives on the new motor, and the old motor didn't have the issue, there must be something wrong with the motor. They are shipping a new replacement motor. I'm very happy with AutomationDirect's handling of the problem. Boy, I sure hope that fixes the problem.
 
I got a tracking number on the replacement motor - FedX says scheduled delivery is TOMORROW!! Imagine that - that is some fast warranty work.

I replaced the rear bearing on the old motor and installed to grinder with the old VFD drive. Right now it's running good - smooth at least. I won't know about tripping on error codes until I've used it some. I think I'll button it up now and do a bit of grinding - getting metal strips ready to put into a billet. Lite grinding will tell, the tripping on error codes were not related to heavy grinding.
 
An update - did a bit of lite grinding this morning with the old repaired motor and old VFD. Old motor runs smooth, but still have some issues with tripping with the VFD. I planned to swap new VFD to see how it worked with old repaired motor, but FedX delivered the replacement IronHorse motor. Installed new motor to old VFD drive - runs smooth, did some grinding with no trips. Not sure how long this will last, but at least the new motor is running smooth. I think the "cogging" problem was with the old motor.

I must give AutomationDirect a big "attaboy" for their service - they FedX'd the replacement motor with overnight service.

Later
 
I've been real happy with the HuanYang VFDs. I wrap a filter cloth around them to protect from dust and never had a problem. I do need to wire the fan to the output, as it gets annoying that it runs all the time for no reason.
 
I've sorta switched to the A2 series of VFD - cheap (2hp for $74, 3hp for $80), and very easy to setup. Also that blooming fan only runs when you are grinding. As soon as you stop grinding the fan stops. MUCH better than it running all the time.
 
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