Eliminating noise/vibration with KBAC-27D?

A

armstrom

Joined
Mar 26, 2017
Messages
6
I've been collecting parts for a grinder and got around to wiring up my 1.5HP motor and KB VFD this weekend. I'm getting really bad vibrations at any setting below 60Hz (50% speed with the 2X option enabled, 100% in regular mode)
Of course, I've searched for answers and found the following threads, none of which have an real solutions:
http://www.bladeforums.com/forums/s...D-saga-goes-on-!?highlight=KBAC-27D+vibration
http://www.bladeforums.com/forums/s...ith-VFD-KBAC-27D?highlight=KBAC-27D+vibration

The motor is not mechanically out of balance since it runs smooth as can be at full speed. I tried adjusting the CL and COMP trimpots to no avail. The motor is completely unloaded.

My setup (All parts are new):
KBAC-27D on 115V (20A circuit)
Hallmark 1.5HP 1725RPM TEFC 56c motor
All wiring is 12AWG (12/3 for the plug, 12/4 to the motor) The motor chassis ground is tied to the VFD chassis ground which is tied to the house ground.

Any suggestions? This VFD seems to be "the standard" so I'm a bit surprised to be having problems with it. Sadly, I do not have a second motor to test with.

Thanks!
-Matt
 
I would try leaving it plugged in, power on, but not running for at least an hour. Manual states that if the drive has been in storage for more than a year you need to do that to revamp the bus capacitors. This was The manufacturers recommendation to me when I had a similar problem.
 
It seems like I've read that electric motors that aren't "inverter duty" don't always react well to some of the harmonics from a VFD and adding a "reactor" in line can help smooth some of that noise out and make for a smoother (and cooler) running motor. I think an old line reactor could be found on the bay for pretty cheap. Might be worth looking into.
 
Thank you both for the replies.
Tiller: I somehow missed that section of the manual so I will try that as soon as I get home. You would think something that important would be on a tag or something in addition to being buried in the manual.

Nathan: My motor is advertised as being inverter duty. However, it seems a suitable line reactor would only cost about $70 so I may try that if no other solutions work out. Thanks!

-Matt
 
Something else to consider is how clean the line voltage coming from your panel to your VFD is. It may be worth trying it on a different circuit, though I suspect Tiller's suggestion will straighten it out.
 
The line voltage should be pretty clean. I ran a dedicated 20A circuit for my shop outlets in the basement. The only other things plugged in to the circuit are my FIOS box (basically a switch mode power supply) and a small chest freezer. I'll unplug the freezer to make sure it's not mucking with things (doubtful, but worth a shot!). I will eventually pull a dedicated 20A circuit just for the grinder so I can run it at the same time as other tools, but I figured I would get it working first :)
-Matt
 
Are you doing your testing with a wheel on the motor ?


I had noise vibration and jumpiness when I ran with a bare motor shaft.

The addition of the drive wheel seemed to smooth it out.




Also
Have you tuned the settings using the beaumont setup sheet ?
 
Yes. I installed my drive wheel but not the rest of the belt drive system since I don't have my grinder chassis yet. When I install the drive wheel it actually vibrates a bit at full speed (I think the wheel is out of balance) but the low-RPM noise and vibration does not go away. I did try "loading up" the wheel with my hands wearing a thick pair of leather gloves and that does seem to help some but I have to almost stall the motor.
-Matt
 
I have some vibration at around 10 to 15% or less with my kbac-27d as well. IIRC, it goes completely away if I set the jumper to VT (variable torque) vs. CT (constant torque), BUT, I lose all my torque on the low speed, so I've kind of been living with it. I know I've left the VFD on (but not running) for several hours at a time, but I'm not sure that it did anything for the vibration in my case.
 
What Hz is that?

I think most motors run for crap below 30hz. My 0-100 is set to be 30 to 200 Hz.
 
kuraki said:
What Hz is that?

I think most motors run for crap below 30hz. My 0-100 is set to be 30 to 200 Hz.
Click to expand...

I have an 1800RPM motor set at 2x speed, so it's definitely below 30hz. As you creep up, it definitely goes away.
 
Yeah, in my case the noise/shaking starts at around 20% (24Hz) and doesn't really clear up until 50%(60Hz) everything above 60Hz is buttery smooth.

-Matt
 
armstrom said:
Yeah, in my case the noise/shaking starts at around 20% (24Hz) and doesn't really clear up until 50%(60Hz) everything above 60Hz is buttery smooth.

-Matt
Click to expand...

Did the bus cap trick improve anything? How about changing the torque jumper?
 
Not really. I left the unit plugged-in for a couple of hours and the noise and vibration is still there below 50%. I tried disabling constant torque and it seems a bit quieter but the motor is super easy to stall.
-Matt
 
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