AC Elevator Drive Audible Noise Help Needed.
AC Elevator Drive Audible Noise Help Needed.
(OP)
We've got a Geared Elevator Hoist that is being run by an Imperial AC VVVF Motor. The Motor is rated @ 1164RPM and the Gear Ratio of the Hoist is 87-2.
About a month after this piece of equipment was installed, it began making a hollow droning sound that is at least 18db louder than the AC Hoist itself.
I recorded the elevator hoist running and captured some WAV file snapshots of the change in waveform.
There is a very obvious and distinct change in the soundwave when this droning begins. I have posted a visual snapshot of this waveform here..
http://onfinite.com/libraries/850891/6ce.jpg
Over the last few months it has become worse and worse and we cannot seem to figure out what it causing it.
I have figured out that the sound is sinewave shaped and it peaks at about 330-338 hz.
I have a recording of an elevator run and this sound
T+0- Elevator Start - Normal Sound
T+9.5s Droning Begins
T+10.5s Droning Peaks
T+12s Droning diminishes
T+15s Droning comes back
T+16 Droning Diminishes
T+17s Droning comes back and doesnt come back
T+24s End of Run.
I would be happy to provide a screen video of this waveform (about 30 seconds) if anyone could give me any help with this.
This is a really serious problem for our building and its residents and our current vendor refuses to acknowledge any kind of problem.
About a month after this piece of equipment was installed, it began making a hollow droning sound that is at least 18db louder than the AC Hoist itself.
I recorded the elevator hoist running and captured some WAV file snapshots of the change in waveform.
There is a very obvious and distinct change in the soundwave when this droning begins. I have posted a visual snapshot of this waveform here..
http://onfinite.com/libraries/850891/6ce.jpg
Over the last few months it has become worse and worse and we cannot seem to figure out what it causing it.
I have figured out that the sound is sinewave shaped and it peaks at about 330-338 hz.
I have a recording of an elevator run and this sound
T+0- Elevator Start - Normal Sound
T+9.5s Droning Begins
T+10.5s Droning Peaks
T+12s Droning diminishes
T+15s Droning comes back
T+16 Droning Diminishes
T+17s Droning comes back and doesnt come back
T+24s End of Run.
I would be happy to provide a screen video of this waveform (about 30 seconds) if anyone could give me any help with this.
This is a really serious problem for our building and its residents and our current vendor refuses to acknowledge any kind of problem.





RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
Is this going down or going up?
Is there any difference between unladen car and fully laden?
Gunnar Englund
www.gke.org
RE: AC Elevator Drive Audible Noise Help Needed.
Yes. There is a difference. It is worse when an empty car is going down, or a full car is going up. (Seems to be load related)
Michael
RE: AC Elevator Drive Audible Noise Help Needed.
Also, I have noticed that when the car is run on inspection (slower speed?), with a couple of people in it, the noise is virtually non-existent. You really have to listen for it (i.e. put your ear on the hoist)
RE: AC Elevator Drive Audible Noise Help Needed.
Gunnar Englund
www.gke.org
RE: AC Elevator Drive Audible Noise Help Needed.
We did have a consultant out this week who looked at the main gear on the hoist, he indicated the pinion gear seemed to be wearing well into the ring gear. He did notice the "half-moon" wear pattern looked a "little" high (towards the outside edge of the tooth), but didn't feel like it was a big deal.
The history of this started when the lift was installed a year ago.
For the first month (at least) the lift made no noise, since then the noise started and seems to have become significantly louder/worse over the last 60 days.
RE: AC Elevator Drive Audible Noise Help Needed.
Or you aren't sure?
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
Is it possible to alter the speed that the hoist operates at by a small percentage, i.e. slow it down by say 10% and see if there is any change. It is possible that there is some form of resonance going on here.
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: AC Elevator Drive Audible Noise Help Needed.
We're not 100% sure but thats what it seems like..
Mark,
I'll see if I can get my vendor to slow the lift down. I do know that when it runs in "inspection mode" which is considerably slower than full speed, the noise is reduced by 80%. If you REALLY listen for it, i.e. put your ear on the hoist or on the cement posts surrounding it, you can hear it but not from many feet away. Full speed, the noise is totally airborne and can be heard from 1-2 floors away.
RE: AC Elevator Drive Audible Noise Help Needed.
You could either place a small digital recorder right on the gear box or one of those cheap "spy bugs" tuned to an FM radio channel so you can hear what's hitting the microphone directly while standing anywhere.
You can then move your sound pickup to the rails or elsewhere to confirm which is louder.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
For instance, if in Sensorless Vector mode, it has 2 features called AFR and ASR (Automatic Frequency Regulation and Auto. Speed Reg.) that can cause "hunting" of frequency if set up for one type of load, but then used with a different one. The hunting can be tuned out, but it won't take care of it on its own.
If in V/Hz mode, it has an Anti-Hunting feature, that if over tuned when unloaded can cause vibration when loaded, which would decrease with load.
Just a thought.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
scmguru, Can you determine if the sound is originating in the motor or the gearbox?
Am I correct in supposing that frequency hunting in the motor can lead to stresses in the gear train that may cause the noise to be generated and possibly amplified in some other mechanical member, even though the motor may be responsible?
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
If the pitch or level changes with carrier frequency, you may want to add a dv/dt filter or even a sine filter between the drive and the motor to quiet the motor. I doubt if a simple inexpensive reactor would do the job.
If, on the other hand, there is no change when carrier frequency is changed, the noise is likely mechanical.
RE: AC Elevator Drive Audible Noise Help Needed.
You're right waross, that was what my thought was. The hunting of the drive as it tries to find the right level, or the pulsation caused by it overcompensating for a different load, is being amplified mechanically by or through the gearbox / mounting system. A strictly audible whine from a PWM drive would not transmit well through concrete posts and then retransmit through air for 1 or 2 floors of a building. This almost has to be a mechanical harmonic.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: AC Elevator Drive Audible Noise Help Needed.
The loudest section where the droning/humming is coming from the area around the outer bearing supports.
Our consultant noted on his report that the teeth on the ring gear seem to be developing a nice 1/2 moon even pattern but it looks a bit "high" on the tooth. Mentioned something about "lowering" the ring gear for better tooth contact?
RE: AC Elevator Drive Audible Noise Help Needed.
You could be right, but if there is some highspeed instability in the "system" loop, it would reflect as noise from the gearbox. To put it another way, there is possibly some loop oscillation that is causing a pulsing torque rather than a smooth and constant torque. This could cause the gears to be loaded unusualy and may cause additional wear on them.
I would expect that if it was a gear isue, that the oscillation would be present at all speeds. When I look at the data, it appears that the oscillation only begins when the drive settles to run at constant speed. During acceleration, there is no issue. I believe that this is significant and points to the drive or speed. The drive could develop an oscillation that could be speed dependant, so dropping the speed may overcome or change this, or the drive may not have been set up correctly, for example set for open loop vector with an encoder or wrong parameters etc.
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: AC Elevator Drive Audible Noise Help Needed.
As I think back to when the hoist was originally installed and look bag at my logs... there were some "problems" with the controller/drive and the tech had to re-program a number of parameters.. I wonder if that is why the problem did not originaly show up when the hoist was installed.
I made a great audio recording as per one of the suggestions here with the mic directly on the gear area and I applied a bandpass filter to cut out the AC motor noise. What I have now is a perfect recording of what is actually going on, the drone is much clearer and obvious.
Also, nice observation re: accelleration of the elevator. There is no drone for the first 2-3 seconds of the run (the accelleration period). The second the car stops accellerating and is in the high speed mode, the drone starts.
If someone would be interested in listening to this mp3 file I made and comment on it, please shoot me a message at audis4***fastmail.fm (remove the *** and replace w/ @)
I'll keep you all in the loop re: the progress made on this..
RE: AC Elevator Drive Audible Noise Help Needed.
That might tip you off to where it's coming from.
If you have recorded sound and it's over sampled enough, you might be able to run an FFT (Fast Fourier Transform) on the wav to produce a spectral map.
There used to be a DSP toolkit built into Matlab that would let you input a .wav and set up DSP analysis using a graphic interface.
The output looks very much like that of a spectrum analyzer.
The frequency with the most power, could be a direct or a multiple (an harmonic) match for the rotation speed of one of your components.
A microphone is a vibration sensor.
RE: AC Elevator Drive Audible Noise Help Needed.
I did a spectrum analysis of the sound and it looks like the loudest peak is between 330-340Hz with another large peak at around 220Hz or so. This is with the bandpass filter applied.
I've posted the screenshot here.
http://onfinite.com/libraries/852424/73c.jpg
The motor is rated at 1164RPM at 208V/60HZ. The gear ratio on the hoist is 87-2.
Does anyone know how I could use this information to isolate where in the mechanical chain this could be occurring?
RE: AC Elevator Drive Audible Noise Help Needed.
http://onfinite.com/libraries/852426/b42.jpg
RE: AC Elevator Drive Audible Noise Help Needed.
I'm just winging it here.
Can you correlate any of those frequencies to the number of teeth on one of the gears x gear rotation speed?
I see your peaks at 330, 220 and 160, it seems like there's 3 similar peaks out there at 760, 600 and 630.
RE: AC Elevator Drive Audible Noise Help Needed.
Upload it here:
http://www.filefactory.com/
Note the link they issue you.
Stick it in here.
Then we can all hear it by hitting the link waiting the annoying few seconds hitting the none-premium 'download' button.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
file a- no filter recording
http://www.filefactory.com/25650e
file b- bandpass filter (center freq @ about 300hz cutoff 2 octave up and down)
http://www.filefactory.com/7477c8
Screen Capture of Wav File w/ Sound. Note: you'll need the following Camtasia Screen Capture codec to view this..
http://download.techsmith.com/tscc/tscc.exe
Download and install, and then open avi file using windows or other media player
http://www.filefactory.com/068e66
Thanks for the help folks.
RE: AC Elevator Drive Audible Noise Help Needed.
Here are the new good links..
The site will make you wait a few seconds and then you click "Don't want a premium download? Click here to access our free download links"
You'll again have to wait a few seconds after clicking on the link and it will then give you the download option(s).
file a- no filter recording
http://www.filefactory.com/get/v3/f2.php?f=25650e
file b- bandpass filter (center freq @ about 300hz cutoff 2 octave up and down)
http://www.filefactory.com/get/v3/f2.php?f=fa7e71
Screen Capture of Wav File w/ Sound. Note: you'll need the following Camtasia Screen Capture codec to view this..
http://download.techsmith.com/tscc/tscc.exe
Download and install, and then open avi file using windows or other media player
http://www.filefactory.com/get/v3/f2.php?f=068e66
Thanks for the help folks.
RE: AC Elevator Drive Audible Noise Help Needed.
The ele.wav file is miss-named!!! Change it's type to .mp3 if you get an "Invalid File Type" warning.
Nice moaning.. "I want my office moved."
Sounds like a big standing wave..
Thanks scmguru.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
Hopefully someone will hassle the sound file download, and then be able to put their finger right on the problem.
It might be helpful if you could note all the drive's present settings in here. I bet someone will see a problem.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
Any drive wizards out there care to have me list parameters? afr/asr settings etc? let me know what you need and Ill have my consultant write them down.
RE: AC Elevator Drive Audible Noise Help Needed.
Control Method (OL Vector, Flux Vector etc.) Fn A1-02
We just want to be sure of what the last person set it up for. As I said earlier, if there is an encoder then it should be set to "03" for Flux Vector control, in which case there are a lot of other parameters to look at, too numerous to go into, but suffice to say you will need someone with specific Yaskawa expertise to help you further. I would call Yaskawa directly for help or a recomendation if I were you.
If A1-02 is set to "02" for Open Loop Vector control, then go to the following parameters (cut and pasted from the manual):
C8-08: AFR Gain; Factory setting: 1.00
Range: 0.00 to 10.00
C8-09: AFR Time Factory setting: 50
Range: 0 to 1000 msec
Useable only in Open Loop Vector Control Method ( A 1 - 0 2 = 2), these parameters affect the speed response or prevent the motor from hunting. To improve the speed response,
increase C8-08 and/or decrease C8-09. To stop the motor from hunting, decrease C8-08 and/or increase C8-09.
For the ASR, check out all of the C5 group, C5-01 through C5-08. There is too much to that to decribe everything here, but recording it is the first step. Since this doesn't appear to be happening with load step changes on the fly, it may not be associated with the ASR, which is more akin to droop control than the AFR is.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
Simply changing this value from, for example, 1khz to 8khz or from 8khz to 1khz would be an easy reversable thing to do and will eliminate any further wondering about motor magnetic noise.
Once this simple test is made, the more complex stuff discussed at length above can be examined if necessary.
Why not do the simple stuff first?
RE: AC Elevator Drive Audible Noise Help Needed.
C5-01- ASR Proportional Gain 1 --- 20
C5-02- ASR Integral Time 1 --- .200 sec (Factory setting is .500)
C5-03- ASR Proportional Gain 2 --- 20
C5-04- ASR Integral Time 2 --- .500 sec
C5-06- ASR Primary Delay Time --- .004sec
C5-07- ASR Switching Frequency --- 0
C5-08- ASR Integral Limit --- 400
I am going to work on scheduling a Yaskawa tech come out and make sure this is tuned properly and will followup with any progress we make.
RE: AC Elevator Drive Audible Noise Help Needed.
A. d 3 - 0 1 : Prohibited Frequency 1 Factory setting (each): 0 . 0
d 3 - 0 2 : Prohibited Frequency 2 Range (each): 0.0 to 400.0 Hz
d 3 - 0 3 : Prohibited Frequency 3
These parameters allow programming of up to three prohibited frequency points for eliminating problems with resonant vibration of the motor/machine. This feature does not actually eliminate the selected frequency values, but will accelerate and decelerate the motor through the prohibited bandwidth.
B. d 3 - 0 4 : Prohibited Frequency Deadband Factory setting: 1 . 0
Range: 0.0 to 20.0 Hz
This parameter determines the width of the deadband around each selected prohibited frequency point. The factory setting is " 1.0 ", which establishes a deadband of ±1.0 Hz.
EXAMPLE:
Vibration encountered between 30.0 and 36.0 Hz.
SOLUTION: Set d3-01 = 33.0. This is the center of the problem frequency band.
Set d3-04 = 3.0. This will cause the drive to reject all
frequency command values between 30.0 and 36.0 Hz.
A frequency command in the deadband will be converted to the bottom value of the deadband, e.g. a command of 33 Hz would result in a run frequency of 30 Hz.
---
I'd be willing to bet that an experienced drive tech could use dial out the problems we're having..
RE: AC Elevator Drive Audible Noise Help Needed.
There are two possible issues here that involve the drive. One is the possibility of a system resonance which is frequency dependant. This can be a real problem in some installations and is a system issue where the system is a combination of the drive, motor and driven load.
A small change in frequency will highlight whether this is the problem If it is, then it is a matter of avoiding the resonant frequencies.
The other possibility relates to the internal feedback systems within the drive. If the feedback parameters are incorrectly set, the drive can go unstable and hunt. Many drives can be easly set to V/Hz which eliminates the closed loop systems. If the drive can be easily set to V/Hz mode and this eliminates the problem, then there is probably an issue with the drive setup.
There can also be an interaction between the carrier frequency and the motor characteristics and this can be easily checked by altering the carrier frequency, but in this case, due to the noise occuring only during run, I would not expect this to be the major issue. - do not discount it though.
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: AC Elevator Drive Audible Noise Help Needed.
I'm also not too sure setting a skip/jump frequency on an elevator application is a good thing either. Even though you are using a variable frequency drive it is only using a relatively small number of speeds and is therefore not ideal to 'vary' the speed as a skip frequency would invoke. Sure, use the VFD to find the problem but knowing Yaskawa's experience with elevator applications, I would be surprised if it is a setting up issue with the drive.
RE: AC Elevator Drive Audible Noise Help Needed.
The encoder can however be used in either FVC or V/Hz mode. V/Hz may make sense in that regard because of what Marke said. The point is, we can second guess this forever but in my mind, you need to pressure the system supplier to answer these questions. It would not be the first time a technician came up with a solution in the field that had unforeseen consequences later, then his boss backs that decision to avoid a callback by telling you "It's normal, live with it."
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
Does "AC Mode" correspond to any drive modes of this drive?
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
That's like saying your car engine is running in "internal combustion mode".
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
Will they actually be able to sort it out??
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: AC Elevator Drive Audible Noise Help Needed.
For your sake let's hope it was a sarcastic answer, kind of like the old Boy Scout prank of asking unwary campers to go around asking to borrow a left handed smoke shifter. Otherwise you have bigger problems to deal with if your drive techs can't answer that question. Since it appears to not be your field of expertise, ignorance is no sin. But for a drive technician to give an answer like that and mean it, that is big trouble.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: AC Elevator Drive Audible Noise Help Needed.
I did notice something however on the display screen. It seems like the noise is corresponding to a value called Torq Ref.- It hovered around 8%, but when then when the noise got really loud, it jumped up to 11-12%.
Also the output frequency was jumping around..For example.. it peaks at 55.XXHz.. The XX values were changing multiple times a second.
What a drag...
RE: AC Elevator Drive Audible Noise Help Needed.
Just another blind guess:
The jump in torque could indicate a change in the load as it is traveling, possibly something binding or dragging (pun reference to your earlier comment intended). The drive may be struggling to maintain control, so there are pulsations in the mechanical drive train as it tries to keep things moving consistently.
I think you need someone with a keen eye (and ear) and a lot of experience in hoist controls to take a look at this in person. If the elevator contractor is unable to help, look for another one or someone who deals with industrial hoist systems. That may be tricky though, elevator work requires some licensing and insurance issues that may interfere.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: AC Elevator Drive Audible Noise Help Needed.
This has been a fascinating thread - thanks to all.
----------------------------------
I don't suffer from insanity. I enjoy it...
RE: AC Elevator Drive Audible Noise Help Needed.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: AC Elevator Drive Audible Noise Help Needed.
We pulled the fuses and we now use the stairs - a lot fitter now......
rugged
RE: AC Elevator Drive Audible Noise Help Needed.
Update, Drive was changed to Flux Vector. Noise is still there, loud as ever. Our maint. has not done anything to move this forward. A large punch list was sent to this vendor in Mid April w/ a 30 day time frame, it included this issue. Next step, litigation.
Other issues on site here, we've got a passenger elevator w/ a DC Gearless hoist that keeps shaking BADLY after upgrade to a new Controller.
We've got another that crashes about once a week with multiple faults.
Its a mess...
RE: AC Elevator Drive Audible Noise Help Needed.
Jokes aside my thoughts are with you....
weve had problems with a company a while back with a refurbishment - it happens to us all from time to time.
Rugged
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
respectfully
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
respectfully
RE: AC Elevator Drive Audible Noise Help Needed.
Sorry I came in so late on this one, I just saw your post. My first instinct on this problem is to check the drive output with an O-scope. Look for a properly formed square wave.
From my experience working on the G5 series drives the gate driver section can start to fail and cause motor vibrations/noise but still run the motor. The optical isolators and capacitors on the gate driver circuits begin to break down with age. This condition is true with most drive manufacturers. A quick check of the output waveform may shine some light on your problem.
Good Luck,
George Myers
Delta Automation
George Myers
www.deltaautomation.com
RE: AC Elevator Drive Audible Noise Help Needed.
RE: AC Elevator Drive Audible Noise Help Needed.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: AC Elevator Drive Audible Noise Help Needed.
Ya you Keith.
LOL