Issue with PM3520 VFD

[Dick Strauss]

Has anyone had an issue with their VFD for their PM 3520 showing an Occ error?

A friend has a PM3520A (it is long out of warranty) that keeps tripping the internal breaker in the VFD and shows this error without any load on the motor (no belt=no spindle). The error is related to the output devices in the Delta brand VFD pushing too much current. I checked everything (main and remote switches, all wires, rheostat, braking resistor, motor resistance, etc) and everything checks out okay. The spindle turns normally with a very slight twist of the handwheel as usual. The motor is not shorted...I checked all pathways. I was able to unlock programming through 00-07 programming menu. I changed the ramp time to 10s and max frequency to 45Hz (I found that it triggered the code as the freq went above about 50Hz even with the long ramp time) I also made sure that no current boost was activated. It runs fine now without fault albeit slower than the oem setting of the max frequency of 130Hz. I don't want to tear into the VFD checking things as long as it still limps along.

PM wants $500 for a new Delta brand VFD that has to be programmed (I don't expect PM to cover it because of the age of the lathe). Does anyone repair these things for less than $500 that I've seen online?

Once it dies completely, I'd help him replace it. Has anyone here replaced it with a $160 2HP Teco FM50 VFD or similar and had excellent results (same smoothness and no extra noise)? I've used the 3HP Teco but don't know if they will produce the same smoothness in his lathe.

Be safe,
Dick

[Dick Mahany]

I needed to replace one on a Jet 1642-2 a few years back. Folks over at the AAW recommended this direct Delta OEM replacement at about half the cost http://www.galco.com/buy/Delta-Products/VFD015S21U. I believe the 2hp Jet and the 2hp PM motors and VFD are the same. Just check your model number to be sure the replacement is the same. The AAW guys also have instructions there on programming it. I can't remember the exact location, however a search should turn it up quickly.

[Dick Strauss]

Dick,
Thanks for the info. That looks like a pretty good price for a direct replacement.

I don't know if my buddy had a power surge hit his VFD or if the electronics are just starting to develop issues from age/temperature cycling.

[Josh Bowman]

I looked up the error code in the delta manual. OCC is "insulated gate bipolar transistor" or IGBT error. Now that cleared things up
Best I could figure out from the manual it's a short circuit failure. Maybe insulation break down.
I put a TECO Vfd on my metal lathe. It is probably a cheaper direction to a Delta.