Kbac 27d VFD Faults!

P

Parksknives

Joined
Jan 26, 2020
Messages
2
Hello all.

I was using my grinder the other day, doing some light sanding on some wood, then I shut the vfd off ( kbac 27d). When I turned it back on only maybe an hour later, I get this slow flashing red status light. Manual says short circuit, and to check motor leads. I am an electrician by trade so I know how to identify a damaged wire, as well as check the motor. I eliminated the main power on / off switch on the front of the drive, and removed the motor leads, and still get the same short cct fault. Has this happened to anyone? I’m speculating that some component on the board has failed, but seems unlikely as the drive is only a year old and it failed during light use. No research online has been useful so far.

Thanks.
 
Try leaving the power off for a while, see it it resets.

Failing all that, the TECH service at KB - on the phone
Not customer service.
They will walk you through
 
Last edited:
**UPDATE**

After discussing my problem with a coworker who is a bit of a vfd guru, he sent me a document with a testing procedure that identified my problem. Turns out i had fried a IGBT chip cause it the short circuit fault.
I purchased a new IGBT chip, as well as some spares. They are about 5 bucks a pop. They have not come in the mail yet, but I’m 99% sure this will solve my problem. The reason for the short ( my best guess) is that I am using the DC injection breaking feature and had the decal trim pot set too high while using a 10” contact wheel. I never had issues with the flat platen, but there is a lot more friction to help with the slowing. In the future I will either switch to the regenerative breaking function, use the dc injection, but lengthen the decel time, or just pay more attention and slow the machine down with the speed control knob before turning off the machine.

Thought other may like to know that it is a possibility to blow something up if you are using the DC injection and have it dialled up for quick stopping and you are using larger contact wheels.
 
Parksknives said:
**UPDATE**

After discussing my problem with a coworker who is a bit of a vfd guru, he sent me a document with a testing procedure that identified my problem. Turns out i had fried a IGBT chip cause it the short circuit fault.
I purchased a new IGBT chip, as well as some spares. They are about 5 bucks a pop. They have not come in the mail yet, but I’m 99% sure this will solve my problem. The reason for the short ( my best guess) is that I am using the DC injection breaking feature and had the decal trim pot set too high while using a 10” contact wheel. I never had issues with the flat platen, but there is a lot more friction to help with the slowing. In the future I will either switch to the regenerative breaking function, use the dc injection, but lengthen the decel time, or just pay more attention and slow the machine down with the speed control knob before turning off the machine.

Thought other may like to know that it is a possibility to blow something up if you are using the DC injection and have it dialled up for quick stopping and you are using larger contact wheels.
Click to expand...

I'd love to read that. Can you share it ?
 
Parksknives said:
**UPDATE**

After discussing my problem with a coworker who is a bit of a vfd guru, he sent me a document with a testing procedure that identified my problem. Turns out i had fried a IGBT chip cause it the short circuit fault.
I purchased a new IGBT chip, as well as some spares. They are about 5 bucks a pop. They have not come in the mail yet, but I’m 99% sure this will solve my problem. The reason for the short ( my best guess) is that I am using the DC injection breaking feature and had the decal trim pot set too high while using a 10” contact wheel. I never had issues with the flat platen, but there is a lot more friction to help with the slowing. In the future I will either switch to the regenerative breaking function, use the dc injection, but lengthen the decel time, or just pay more attention and slow the machine down with the speed control knob before turning off the machine.

Thought other may like to know that it is a possibility to blow something up if you are using the DC injection and have it dialled up for quick stopping and you are using larger contact wheels.
Click to expand...

I just had a similar situation with my KBAC-27D … I have some IGBT replacements on order as well.

P Parksknives did you have any luck soldering the IGBT back in? I can't for life of me see how to un-fasten the board from the VFD box in order to get the old IGBT out.

Any tips?
 
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