KMG Grinder VFD power issues

R

Rythorne

Joined
Sep 27, 2015
Messages
61
Hello, thank you in advance for reading my issues and attempting to help if you can. I setup my KMG grinder today with a friend. I am positive everything is setup right as far as power and used all good connections in regards to the motor and VFD. When I start the VFD everything is fine until around 40 %. Then it almost begins to sputter and the lights flicker. When I get to around 50-55 its fine again. Is this just that there is the most electrical resistance and load on the motor at that percent or is this a problem anyone else has experienced and has a different solution? Im running it on 110 outlet for now and the jumper is set to the proper location, and the jumper is also set to 2hp because its a 2 hp motor. (I dont put it to 1.5 hp because of the actual output of the 2hp motor at 110 voltage is actually 1.5hp do I?) Thank you again. Otherwise runs like a beast and is so solid it brings a tear to my eye.


EDIT PS - If the consensus is that its an electrical issue because I assume the outlet is run in line with the lights then I will just have a 220 ran outside on its own circuit and be done with it.
 
Are you running at 2X line freq jumper or 1x, does it happen with both jumper positions? Also is this only when you are grinding heavily or when grinder is "unloaded" as well? Cause the motor wouldnt be loaded down to max if it is just driving the grinder with no knife grind load. I run a 3hp motor on a dedicated 220Vac circuit so I have not seen this.
 
Electrical resistance ? No ... Load? No ... Unless you have a mechanical load applying torque. The current rise from start up is caused by slip ... The field revolving faster then the armature induces current in the armature known as counter EMF.

... I'm assuming you have a 3 phase motor ... Now assuming you have a single voltage ... Maybe you have a multi ... One of the voltage or the voltage should be 208 volts.

Does the voltage on the name plate match the outlet you are using? If the name specifies a certain potential I suggest you follow it. Read the manual for the code. Those flashing lights is the drive telling you something ... Learn to speak it's language.
 
Both lights green. Running on a 110 outlet. Jumper set to that. Not home I'll check the 2x jumper when I get home.
 
you're certain the motor is properly wired? 3 phase motors are simple ... it's properly wired to the drive load terminal? maybe post a video. Trouble shooting electrical is hard from a distance. make sure all setting are correct to accomodate that motor
 
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When in 2x and 1x (I assume I move the jumper down one pin to 2x leaving the pin next to 1x open) it still isn't smooth at around 30%-50% which is where I've narrowed it down to. However that's only on slow accel. Under decal the problem is completely gone. I'm thinking its because its run in line with everything in the garage.

When I was mentioning load and such I assumed this like any motor has a sweet spot and the lower rpms were not it because under higher RPM its fine. Again, total guess. Thanks for all the help.
 
post a video , you're setup might be fine. Like i said it's hard to troubleshoot from a distance or without seeing what the motor is behaving like. Try it under load to see what it behaves like. is there anything else running on the same circuit that the outlet you are using is on?
 
i'm wondering if the others are using DC link chokes? What kind of vfd is it? i wish i was there to try a few things. what ever it is its simple but it has me stumped. it's nothing mechanical is it? Can you try another motor on it?

i'll have a talk with one of the electrical engineers at work see what he thinks. It can't be much what ever it is.
 
I'm kind of embarassed to be honnest , these set up's are generally very simple. Plug and play VFD's and a simple induction motor. I don't think anyone on here is running in line reactors or dc chokes. I'm really curious now. I would try on a 240v circuit for fun or another motor to see if it does the same.
 
I'm curious as to the OP's original question. What should the jumper be set to if you are running a 2hp motor on 110V input as 1-1/2HP is the largest motor recommended for 110V. Anyone running a 2HP motor on 110V?
 
It could be one of the trimpots for slip compensation, boost, accel, or current limit. First I'd check the manual and make sure all of them are in their default positions.


Some, can cause some whacky operation if set to extremes, and I've had some motors that needed slip comp to be adjusted from default to run smoothly.
 
The pots are all set to kmg recommendations. Based on their site it says the motor output will be 1.5 even with a 2 hp motor on 110v. I believe they say don't touch comp but let me look. Don't reall. Have the 220 option or the motor option minus a 1x30
 
Well, you can test the electrical concern by making sure everything else on the same circuit is turned off.

Afaik it shouldn't matter if you've got the jumper set to 1.5hp or 2hp, it's just a limitation of how much current the VFD will pull with 110 input.

Yes, wiring up a 220V circuit to the VFD will give you more HP, and the gain from 1.5-2hp isn't insignificant.


Did you purchase this motor from Beaumont or on your own?
 
Motor and VFD are from Beaumont. Prior to leaving for work just now I did some adjustments. I first tried turning everything in the garage off. No effect. Next I adjusted every pot. No adjustments on any except min/max effected anything. When these were adjusted it simply moved on the dial real out where the problem occurred. At the same RPM it seemed to have to same problem. I also changed the motor size pin to 1.5 hp. This made the issue worse. Next I moved the plug from 120 to 230. This caused the motor not to spin at all.
 
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