AC Motor Control Problem

Bill Thomas

Bill Thomas

Joined
Jul 7, 2013
Messages
64
My TW-90 is dead. The motor control is a KB Electronics KBAC 27D. I just noticed I accidentally left the power on for about 5 days. I went to the shop this morning and it will not turn on, no power lights appear. I checked the inline 25 amp fuse and it appears to be good. I'm trying to finish a couple of knives for Christmas. Does anyone have a suggestion of what is going on? Thank you.
Bill
 
Last edited:
Bill Thomas said:
My TW-90 is dead. The motor control is a KB Electronics KBAC 27D. I just noticed I accidentally left the power on for about 5 days. I went to the shop this morning and it will not turn on, no power lights appear. I checked the inline 25 amp fuse and it appears to be good. I'm trying to finish a couple of knives for Christmas. Does anyone have a suggestion of what is going on? Thank you.
Bill
Click to expand...
I'm assuming you already checked power at the vfd.
 
I must say my electrical knowledge is very minimal. About all I know is to check fuses and main breakers. I'm not even sure what the VFD is. Thanks for your help.
 
Variable Frequency Drive. If your breakers are good, that's a start. Is anything else on that circuit? You really want to check the circuit right where it enters the VFD.
 
Kevin, Thank you for your help. The circuit is good with nothing else on it. No power is getting to the VFD, in working condition there is a power light that is visable, but not now. I would have thought that if there were overheating or power overload it would have tripped the in line fuse inside the VFD. The inline fuse doesn't look to be burned or broken but I will have to get another one to rule that out.
 
Bill Thomas said:
No power is getting to the VFD, in working condition there is a power light that is visable, but not now.
Click to expand...
IF power is not getting to the VFD itself, then hopefully the VFD might be good. Can you check voltage at the power inlet terminals? That is the very first step.
 
It's working now!!!!! Didn't do anything but unplug it and let it sit. I guess it was hot and needed a 2 hour cool down period. Learned something new. Thank you guys for chiming in. Sorry for the trouble.
 
It automatically shut down to prevent any damage. You have to remove the power, and restart it. Sort of like a hard re-boot on a computer.
 
I remember when they came out with and electronic circuit to protect power supplies. It was called a "crowbar" circuit. It effectively shut off the power supply if there was a short, overdraw, or other detected problem. The problem was that electronics people didn't know about the circuit, and assumed the power supply was dead. They would swap it out for a new one and everything was fine. The bad one would either go into the junk bin or be sent for repair ... where it would be found to be working perfectly. All that was required to re-start the supply was a full power shut off for 2 minutes.
 
I have an additional switch in a box right next to the VFD. I always turn this off when I'm done so no power is getting to the VFD when I'm not working.
 
I'm glad that your problem is solved. Now, perhaps someone could have a suggestion for my issue. I have a variable speed Bader BIII. When I turn it on the power to the motor is intermittent. It cuts on and off every second or so. Enough to keep the motor turning, but at about half the normal rpms for that set point. It doesn't matter what speed I have the controller turned to- it does it at all settings. After the motor warms up, maybe in 5 minutes, it will all of a sudden start working normally, speed up, and run smooth.

Thanks for any input.
 
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