VFD Troubleshooting - KBAC-27D for KMG

H

Hypocrite

Joined
Apr 23, 2008
Messages
234
Gentlemen,

I come humbly before you for some help troubleshooting my KBAC-27D VFD installation.

I have been in the process of setting up my KMG, and this morning was supposed to be the final step... installation/wiring of the VFD.

I am running THIS 2-hp motor that I purchased from Grizzly. It is a dual-voltage (230v/460v), 3600rpm unit. The first thing I did was rewire the motor for 230v as it came prewired for 460v. Below is a photo of the wiring diagram on the motor.

3446859096_39c0af1b08.jpg


I wired it up exactly as shown on the "LOW VOLTAGE" side of the diagram.

I purchased a KB Electronics KBAC-27D VFD to drive this motor. I ran my wires from the motor to the "MOTOR" terminal screws on the VFD. I also wired the "AC Line" wires to a 220V circuit. Below is a picture of the wires inside the VFD.

3446859204_9bb7d93b5c.jpg


I set all the jumpers as recommended in the manual (see picture below):
3446044273_82579b156c.jpg

Jumper Settings
J1 230v
J2 2HP
J3 Automatic Ride-Through
J4 1X Rated RPM
J5 60Hz
J6 Fixed Boost
J7 Regenerative Braking
J8 "Run" Output Relay
J9 Normally Open Stop Contact
J10 Constant Torque
J11 Inverter Duty Rated Motor

So when I finally went to start everything up and connected power to the VFD (plugged in the 230V cord), the VFD powers up and I get a green "power" LED and a slow-blinking red "status" LED. Page 22 of VFD manual says "slow flash red" = short circuit.

So apparently I have a short circuit somewhere. So I re-checked my motor wiring... looks good. I test my wiring from the VFD to the motor... no shorts that I can find. I check the motor wires individually to see if there is a short somewhere in the motor (based on the wiring diagram below)... everything seems to check.

3446858846_34eb246c6f.jpg


So... anyone have any ideas why the VFD is telling me "short circuit"? Any help would be appreciated. Let me know if I can provide any additional info.

Erin
 
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Erin, have you tried connecting the motor directly to the 220 circuit without the VFD? I would first verify that the motor operates while directly connected. Then troubleshoot from there.
 
Cliff,

Can't do... The VFD takes 1-ph 220v in and turns it to 3-ph 220v out. I'd have to have 3-ph 220v in my shop... which I don't. Thanks anyway.

Erin
 
Here's a coupe of really simple thoughts. First, and I know you've already checked this, but in your extension cord wired into your 220, you do have the tan and the black strands tied into the hot 110 legs, right? And green is to true ground (not neutral). Not that it matters, but typically, the lines are wired up with tan being neutral, red and black being hots, and green as ground. Just double check there that the colors are matching on both ends and you're neutral is capped off.

Then, make sure your grounds are a well connected. Remove any paint from the motor housing where your ground is screwed in to make sure you have good contact. And make sure all the wire nuts (if you used them) are secure with no excess exposed wire beyond the nut that could be shorting to the frame. And make sure the extra wires on the motor are capped securely as well.

--nathan
 
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Hyprocrite call the factory guys in Florida.You paid good money for that 27D and that's what they get paid to do ; customer service. After almost a day of scratching my head , I called them and was up and running in 30 minutes.
 
Thanks for the response Nathan.:)

Yeah... black and tan (white) are tied to the hot legs. When powered up, I took voltage across these legs at the VFD... 230 volts. Green is grounded to grounding screw as shown in the first picture, and is connected to the ground spade of a plug on the other end. In the corresponding 230v receptacle, this is tied to ground. I have a 230-volt 1-ph tablesaw that runs off this same circuit no problems.

Below is a pic of the wiring at the motor. I don't see any exposed wiring that may be grounding-out, and I have rewired this once to try and fix the problem. No go. I think the ground conductor is making a good connection to the ground screw and motor chassis.
3446054243_d04df8175a.jpg

I'm wondering if there may be something set incorrectly on the VFD... maybe a trim-pot set with too sensitive. I think that I used the settings that Rob Frink recommends for this unit... but I may have made a mistake somewhere. I think that you can make out the settings of the trim-pots from the second pic as well.

Let me know if you have any ideas.

Erin
 
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Charley75631 said:
Hyprocrite call the factory guys in Florida.You paid good money for that 27D and that's what they get paid to do ; customer service. After almost a day of scratching my head , I called them and was up and running in 30 minutes.
Click to expand...

That's a good idea Charley... if I can't figure it out tonight, I'll give them a call in the morning. Hopefully they don't get the holiday off. ;)

Erin
 
Charley, I'm not sure if I'm talking about the same thing you are, but if you are referring to the brown piece coming from the line-in cord on the bottom right hand side of the board, it looks like a piece of paper insulation from the cord. I say that because I used the same type of cord for my wire-up.

The motor is wired up the same as mine (same motor, in fact from Grizzly). Check with the manufacturer I guess. Good luck and let us know what it is when you figure it out.

--nathan
 
Everything looks correct. Are you aware that the Run switch actaully has 3 positions start, run, stop. The "start" position is spring loaded in the upper most position, then it clicks back to the mid position for "run". This is the most common reason why I get phone calls....it doesn't run because you have actaully "started" it.

You might already be aware of this.

-Rob
 
Yeah Rob... I know about the switch movement. The VFD actually "faults-out" to "short circuit" (slow flashing red light) immediately upon being connected to power (plugged into recept). You probably noticed that I currently do not have the power switch installed... it is currently on order... but shouldn't AFAIK affect the machine running.

Thanks for the help Rob.

Anyone else with ideas feel free to chime in. I think that the first thing that I am going to try is to rewire the 3-ph leg from the VFD to the motor. I originally used 10/3 romex because it was the only wire I had laying around with three wires and a ground. It was a real PITA to work with, so I think I'll pick up a couple of feet of #14 stranded extension cord instead. The set screws in the VFD don't clamp evenly over the big #10 wire. Don't know if this is THE problem, but being able to remove these wires easily for diagnostic purposes can't but help.

Erin
 
Yeah, one problem with solid strand wire is that it can sometimes short in the middle of the length if bent, or if there is a notch in the solid wire somewhere. Definitely pick up some stranded and try it out.

Strange that it faults when plugged into the recepticle with the motor switch in the stop position. That makes me think it's on the VFD/line-in side of things as opposed to the motor, unless the VFD is checking the circuit to the motor on power up as well.

--nathan
 
Check that you have 230V at the input terminals of the VFD using a DVM. Disconnect the cable connecting the motor to the VFD, at the VFD end, to eliminate the motor and motor wiring from the equation. Then apply power to the VFD. It the fault occurs immediately, as you have stated before, the fault is in the VFD. It is likely that your VFD is one that performs a self-diagnostic check when power is applied. You will have to consult with the manufacturer regarding this issue. Most manufacturers do not publish details about internal faults and refer you back to their Service Department. If it is an internal fault, and it is under warranty, the manufacturer should cover you. There is a small chance that some incorrect combination of settings may produce the fault that you are seeing. Again, you would have to consult with the manufacturer to work this out.

Take care.

Phil
 
Just confirming...(ignoring the status lights)...does it run when the power is "on" and you click it to "run"?

You can test for a short in the motor using the internal diagram that you posted. For example, 1&4 should only have continuity to themselves and nothing else, the same with (2&5) and (3&6)...and the trio of (7,8 & 9).

Also check each set to ground (motor frame)...which should be open circuit.

-Rob
 
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Phil,

Great recommendation. I'll give it a go.

Rob,

I did test all the legs of motor as you suggest... everything looked OK. I did not, however, test all legs to ground... I'll check that right away. Well... after I figure out why my Legacy is overheating anyway.:grumpy: Fist thing's first.

Thanks for the suggestions guys.:)

Erin
 
Phil,

I disconnected the wire to the motor (I hated that stiff #10 romex anyway), then plugged the VFD back in. The short circuit error was gone. VFD was in a "Stop" status (steady yellow light). I had purchased a section of #14 stranded cord to replace the romex and installed. Powered it up and... bingo. Everything A-OK. Flipped the switch to run and.................... we have lift-off.:D

Thanks for all the help Phil, Rob, Nathan, Charley & Cliff.:thumbup:

Erin
 
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