VFD problem

Les Voorhies

Badge Boss Admin Dog Catcher
I have a KMG with the 2HP variable speed, it was running fine the 1st half of the day but a little while ago when I turned it on it sounded and felt wrong, it kind of vibrated. I shut it off and looked ofr the source of the vibration, couldn't find anything so I turned it back on and it just oscillated back and forth.

I'm hoping this is a common problem and maybe someone here can point me in the right direction because I have no clue how to troubleshoot these things.
 

Wayne Coe

Forum Owner - Moderator
Les, I haven't heard of anything like this. Is it the motor or VFD. I suspect its the motor. The VFD is probably a KB drive. You could call KB at 1-800-221-6570. Their tech support is very helpfull. You may have to send the VFD to them but the repair will probably be cheaper than a new drive. If you do have to have a new drive call on me and I will help you. If they take care of it or give you any information please let us know.
 

Les Voorhies

Badge Boss Admin Dog Catcher
I don't know if it's the motor, because it oscillated back and forth (like it can't make up its mind to go forward or reverse) I assumed it was the VFD, it is a KB and I've found a replacement but I haven't pulled the trigger on it yet (wouldn't ship until tomorrow anyway). I was talking to Jim Poling tonight and there is one more thing I need to check but I can't find my meter. I'm wondering if the the circuit breaker might have gone bad and is only delivering 110v of the 220, so tonight after I get my granddaughter to bed I'm going to go out and switch out the CB. If that doesn't work and I don't hear any other ideas I'll have to buy the new one. If I do that, then I can send this one out for repair and have a spare, I can't afford to have it down for more than a couple days.
 

Ausbrooks

KNIFE MAKER
Sounds like you have a bad power component, probably an SCR or IGBT. I would demand a replacement. Don't expect to see this with a DVM, as the wave switching is so fast you'll never see it.
 

Les Voorhies

Badge Boss Admin Dog Catcher
Sounds like you have a bad power component, probably an SCR or IGBT. I would demand a replacement. Don't expect to see this with a DVM, as the wave switching is so fast you'll never see it.

Hmmm, I was looking at the QBT or the STVN, but the GBT and the BLT look suspicious too.... :D I'm sorry man, I have no clue what an SCR, IGBT or DVM are.
 

Ausbrooks

KNIFE MAKER
Sorry Les! the SCR is a silicone controlled rectifier, and the IGBT is a Internal Gate Bithermal Transistor. http://www.allaboutcircuits.com/vol_3/chpt_7/5.html
They are basically the electronic gadgets inside there that create an AC wave that your motor will digest. If you see a burnt component you could consider replacing it if you are handy with a soldering iron, otherwise I would ship it back and have them repair or replace it.
 

Les Voorhies

Badge Boss Admin Dog Catcher
Sorry Les! the SCR is a silicone controlled rectifier, and the IGBT is a Internal Gate Bithermal Transistor. http://www.allaboutcircuits.com/vol_3/chpt_7/5.html
They are basically the electronic gadgets inside there that create an AC wave that your motor will digest. If you see a burnt component you could consider replacing it if you are handy with a soldering iron, otherwise I would ship it back and have them repair or replace it.

Thanks for the clarification :) Surprisingly I can solder but otherwise this job is way over my head, I'm going to buy another identical drive and send this one in for repair, then keep it for a spare.

Thanks for the help everyone.
 

scott.livesey

Dealer - Purveyor
les:
if you have a multimeter, check power in and power out of the drive, power out with motor connected and disconnected. leave motor disconnected and check the windings. if this sounds like Greek, get the new one and ship the broken one back.
from your symptoms, i would say drive, just make sure all the knobs, buttons, displays...... are correct before shipping. I used to love telling folks that drives(radios,motors...) usually don't work when the on/off switch is in the off position

the old sailor (AT1 USN Ret.)
 
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