Powermatic 3520a VFD error

Kirk Amidon · 2025-09-14T06:40:57-0400

Have a 3520A which has the Delta VFD B PU01 on it. The VFD is throwing an occ error code. I found the manual, in the troubleshooting section found this error code (occ), and checked the easy stuff - wire connections, etc. No bueno.

One of solutions is to increase the parameter for acceleration. I found the parameter (01-09) and it is set to 5, while the manual shows factory is 10. However, when I try to change the value the VFD displays ERR and does not accept any change to the value. Is there something programmatically that prevents parameters from being changed?

I can work around the issue by getting the drive belt super loose, starting the lathe and then tightening up the drive belt, but this is clearly not a good method. If I try starting the lathe with a tighter belt, the motor starts to turn, and almost immediately loses power and starts to coast down. There seems to be no braking in this situation.

At this point, I believe a new VFD is in order. I've searched around for replacements, and had experience with a TACO brand VFD that I used on a previous lathe. Basic question is beyond matching the 240 single phase input, and the 3 phase output for a 2 HP unit, what other specs are going to be vital? Several members here recommended a company called Dealers Electric, who does stock Teco VFD's and I found this one: L510-202-H1-U.

Curious if there are any other recommendations, or things to try before buying?

Darryl Fective · 2025-09-14T09:00:15-0400

I can't remember for sure, but that might be the message when you try to change a parameter without having entered the unlock password.

EDIT: You could try unlocking it with 506 as the password and try again.

Kirk Amidon · 2025-09-14T10:17:45-0400

You are correct. After posting my original message, I found a link with that information. I was able to update both the acceleration and deceleration parameters from 5 to 10; but that did not fix the issue.

I'm wondering now, if doing a full factory reset is a good plan.

Dave Landers · 2025-09-14T10:38:41-0400

Note that the generic factory settings for the VFD itself don't take into account its application/use. They may not be the proper settings for lathe operation. Here's one set of info you might find useful - https://www.aawforum.org/community/threads/re-program-powermatic-vfd-drive.9229/post-85734

The VFD error seems to be pointing a finger at the motor. Might want to have that checked at a motor shop before spending on a new VFD.

Darryl Fective · 2025-09-14T12:32:34-0400

For what it's worth, I've had very good luck with this VFD on Amazon.

Kirk Amidon · 2025-09-14T13:19:26-0400

@Dave Landers what is pushing you towards the motor? The manual for the VFD seems to imply this error is an internal error to the VFD. What am I missing?

Dean Center · 2025-09-14T22:35:34-0400

Kirk, my question would be, Why now? Why would the VFD show an error message at this time, when it hasn't done it in the 30 years since the lathe was manufactured? Did you attempt something totally different from your usual work? If not, then what else has changed? A bad bearing, a problem with the motor, dust in some stupid spot inside the headstock? Or maybe you're right and the VFD itself has aged out. I wish I had a helpful solution for you.

Kirk Amidon · 2025-09-15T05:36:14-0400

Dean - good question. I don't recall finding any results where someone had a motor failure on one of these lathes, but plenty of VFD issues. 3 phase motors are simple things and generally quite robust. The spindle spins freely in both high and low speed with the motor off.

I've had the lathe 3 or 4 years, and it has thrown errors here and there, when I've tried to take too big a cut. Stupidly, I never paid attention to what those errors were, simply hit refresh and went on my way. I recently turned a larger round into a hollow form. This was maybe 14x16" of punky maple. A couple times while turning this, the lathe shut down, and I definitely noticed a much longer deceleration at those times.

There is a motor shop a couple towns away who will get a call later this morning.

EDIT - also just found the Doc Green site, with a bunch of tests for the control components which I'll run this afternoon.

Dave Landers · 2025-09-15T08:45:15-0400

Kirk Amidon said:
what is pushing you towards the motor? The manual for the VFD seems to imply this error is an internal error to the VFD. What am I missing?

"7. If there are still any abnormal conditions when operating the AC motor drive after a short-circuit is removed and the other points above are checked, it should be sent back to manufacturer"

I think I misread "AC motor drive" (aka their name for the VFD) as "AC motor". So never mind

Still, if you have a motor shop nearby (and they can test things for a reasonable price), seems a prudent step.

Good luck with it!