AC Elevator Drive Audible Noise Help Needed. 6

[scmguru]

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.

 

[ozmosis]

I think that means he doesn't know.

 

[itsmoked]

ummm... yeeeEEEEeeeyeah I would agree with sed's assessment. Maybe we are seeing the whole problem... Yah think?

Keith Cress
Flamin Systems, Inc.- <

http://www.flaminsystems.com>

 

[jraef]

LMAO!~
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

 

[Marke]

The worrying thing to me is, is this a true reflection of their level of understanding of the equipment and problem, or are they just being a smart A...?
Will they actually be able to sort it out??

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[jraef]

smcguru,
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

 

[itsmoked]

scmguru; Stick with the stairs..


Keith Cress
Flamin Systems, Inc.- <

http://www.flaminsystems.com>

 

[scmguru]

Just an update.. looks like the drive was set to Flux Vector sometime this week. Noise is still there.

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...

 

[jraef]

Sounds like the drive is in torque control mode. You must have a spool collecting the elevator cable. Torque mode is used to keep a constant torque on the cable regardless of spool diameter as it reels in and pays out cable, as well as soft start, soft stop and maintain a constant speed at the load (elevator car). The slight frequency drift you see is not unusual, motor speed will be the secondary control point in this application. The drive will allow it to float slightly in order to maintain even torque and not snap the cable when the car is at the bottom or start overloading as the reel diameter increases towards the top of travel.

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

 

[ScottyUK]

Just looking at the drive tuning parameters, the response looks quite aggressive for a large high inertia load. The gain is very high, and the integral time seems very short. Note that I have no experience on elevators at all, but a fair bit on control loops. Aggressive loop tuning, in my opinion, often results from inexperience.

This has been a fascinating thread - thanks to all.

----------------------------------

I don't suffer from insanity. I enjoy it...

 

[itsmoked]

scmguru; Can you update us on this?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ruggedscot]

We had this problem and managed to cure it after a while - took a little thought but now we dont get any noise from the lift. The service engineer wants to use our solution at other sites aswell.....


We pulled the fuses and we now use the stairs - a lot fitter now......

rugged

 

[scmguru]

Keith,

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...

 

[ruggedscot]

scmguru

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

 

[ratio]

My input would've been the pwm frequency avenue that has obviously been investigated, have you had an oil check done on the gearbox? Does the gearbox have a name plate with rated torque writen on it? How does this compare with required torque? Is there a service factor issue? Sounds like the drive is undersized to me.

 

[waross]

Is it possible to bypass the vendor and phone the manufacturer directly. They can probably help and may not be happy that one of their vendors is giving them a bad name.
respectfully

 

[scmguru]

Vendor will not help.. says we need to go through licensed elevator company.. the same one who thinks there is no problem..

 

[waross]

How about the elevator inspector?
respectfully

 

[DriveTech365]

scmguru,

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

http://www.deltaautomation.com

 

[scmguru]

Finally, I've got an onsite visit from the vendor supervisor tomorrow. I will be sure an share all of your input. Vendor still denies there is a problem..

 

[itsmoked]

You just need to stand very close to him in front of an open elevator shaft. Crowd him a little.. He will start to see the problem.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com