Powermatic 3520A inverter problem

Re: Powermatic 3520A inverter problem

Bob Holcombe

Tony, we had a stretch of above average heat and humidity here in NE Kansas a few weeks ago. My 3520A is in my garage and twice at the start of a turning session I shut down with a GFF code. It took a few resets to get it running again.

I don't know if this relates to your inverter problem , but I've been running fine since.

Re: Powermatic 3520A inverter problem

Chuck Engstrom

Hi Tony -- I have not had this problem but I did, some time ago, download the manufacturer's manual for the AC motor control. Mine is a Delta VFD015B21A, which seems to be the one typically supplied on the PM lathes. It's available at http://www.delta.com.tw/product/em/drive/ac_motor/download/manual/VFD-B_manual_en.pdf. It's 239 pages, 4.9 megabytes, and very dense going unless you're a real EE, but it does show the error codes.

Page 6-4 says GFF is a "ground fault" problem with these comments:

"When (one of) the output terminal(s) is grounded,

short circuit current is more than 50% of AC motor

drive rated current, the AC motor drive power

module may be damaged.

NOTE: The short circuit protection is provided

for AC motor drive protection, not for

protection of the user.

1. Check whether the IGBT power module is

damaged.

2. Check for possible poor insulation at the

output line."

I hope this is of some use to you. Could be a wiring problem, as PM suggested; in any case be sure to unplug it before you go digging around inside it. Hope you find a fix pronto --

Best regards -- Chuck

Re: Powermatic 3520A inverter problem

robo hippy

I had an older A that had a tiny fan under the converter. Seems a lot of chips found their way down the heat baffle on the back ans stopped the fan. I put some screen over the top of the heat baffle and that stopped the problem.

robo hippy

Re: Powermatic 3520A inverter problem

Tony Reynolds

Thanks so far for all the replies. No joy in Mudville so far. I've checked all the wiring, cleaned and tightened all the contacts, checked my main wiring and breakers.

The weird thing is it will run for ten to 30 minutes after it has been unplugged for an half hour or so. Having made my living for 20+ years as a troubleshooting electronics tech, this doesn't sound like a wiring issue. It sounds more like an intermittent problem with the inverter itself.

The inverter isn't running warmer than normal and Robo, mine doesn't have the fan, but thanks for the idea. The PM tech says he is sure it's not the inverter, he says they usually don't function at all if they go out. That doesn't sound quite right to me but I haven't any experience with them.

I hate to shell out $500 -$ 600 for a new inverter only to find that's not the problem. Still working on it....

Re: Powermatic 3520A inverter problem

Mavdad55

Tony, hello; I also was an electronic tech in the Air Force, long ago, and later on designed Computer memory for large systems. So here is a suggestion to eliminate a phase winding in your motor from being your issue. The reason I mention it is that winding coatings, when bad react to heat, so if a few to many windings are starting to short then I would think you would also get the Ground fault indication.

First, please make sure you unplug the lathe from your 220v source.

This is a 3 phase motor. If you can disconnect the phase lines to the motor from the inverter and use a low ranging ohm meter to check each phase lead to the neutral wire. If they all measure the same then your motor is likely ok. If one lead measures say 10-20% off from the other 2, then the motor may be bad. If you suspect it, have a motor rebuilder check it out.

Re: Powermatic 3520A inverter problem

walta

With the fault decoded as a ground fault in the motor or its wiring.

Be aware this drive may contain large capacitors that store a charge for a long time do not touch or measure any connection unless the unit has been unplugged for 20 minutes .

Try disconnecting the motor wires from the drive.

With an ohm meter check from each lead to the motor case.

You should get a reading of over 100K ohm.

Also look for any place where the wires may be cover with grease or oil.

If you get a reading under 100k try again at the motor with the leads disconnected.

If you still get the reading it may be a bad motor.

If you readings are 100k to OL look at the drive.

It seems like a thermal problem that you may be able to pin point with freeze spray and a heat gun.

Walta

Re: Powermatic 3520A inverter problem

Harry Robinette

Tony

If you have to get a new inverter,I just bought a new one to upgrade my General it was only $251.00. I believe when talking to the tech's they have one that will replace the Powermatic/Jet.

automationdirect.com

Re: Powermatic 3520A inverter problem

Hal Taylor

Tony, I had to replace the inverter on my 3520A about a year ago. If you have to go that route please get in touch. I have some wisdom for you.