Three blown Powerflex 525s - don't know why

rguimond

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Monday, we had a VFD that controls the spped of a conveyor belt fail on us. Took the replacement out of the box, installed it and bam, it failed, too.

While waiting for a replacement, we meggered the motor and it was fine. To double-check, we brought it to a local moitor shop for testing. Changed the whip from disconnect to motor. Meggered everything from VFD output all all tested OK. There's a load reactor after the VFD

Today, we installed a replacement and it fried when power was applied. Even blew the fuse

Legs are roughly equal - 576, 580 & 588 volts

Any suggestions? The only thing I can think of is a bad local disconnect, but that seems unlikely
 
Check your brake as well as your motor wiring; I've had a shorted brake blow capacitors in the drive, and a shorted brake transistor cause problems on a different occasion.

+1 for powering up with no load
 
Monday, we had a VFD that controls the spped of a conveyor belt fail on us. Took the replacement out of the box, installed it and bam, it failed, too.

.............

Today, we installed a replacement and it fried when power was applied. Even blew the fuse


First replacement "failed" in the same way as the original and the second replacement which "fried"?
Trying to make sure you are not troubleshooting problems that were created during replacement and not the original problem.
Please describe in detail how the original failed.
 
What was the part number on all three drives? Is it possible that you received 480V rated drives instead of 600V rated drives?
 
Add to the "what if" list:
How long was the replacement drive sitting on the shelf without power?

Do you have a Line Reactor? If not, why not?
 
Last edited:
Add to the "what if" list:
How long was the replacement drive sitting on the shelf without power?

Do you have a Line Reactor? If not, why not?

You beat me to the “how long sitting on the shelf question”. We blew a drive once and my boss didn’t believe me when I told him we should have gone through a capacitor re-forming procedure until I showed him a white paper on it.
 
Add to the "what if" list:
How long was the replacement drive sitting on the shelf without power?

Do you have a Line Reactor? If not, why not?

Also important, how long was it working 24/7 without being powered down. Some devices don't like losing power after years turned on (Hirschman switches and S7-400 rack PSU's come to mind).

You beat me to the “how long sitting on the shelf question”. We blew a drive once and my boss didn’t believe me when I told him we should have gone through a capacitor re-forming procedure until I showed him a white paper on it.

Do you have a link for it? I have to have these things in stock and it would be nice not to blow them up on startup.
 
We had 10 or so 525's in one system, continually blowing them up, replaced them with Mitsubishi never had one of those fail in the 10 + years after that.
 
Yes it's my typo it was 2012 so 11 years ago, we started replacing them the first two were replaced a couple of months after the plant was commissioned, this was a piece of machinery built in the states & the other was from Italy, both had AB drives, PLC's & Panelviews, the first two drives were replaced with Mitsubishi (we had no stock of the 525's at the time) but as they seemed to be more reliable we replaced them all after a number of failures within the first 12 months, on another note I don't know why but both the HMI & PLC on the US machine the power was disconnected on an E-stop, we had a number of failures of HMI's on that machine even though it was a 24v unit, I modified the safety circuit so both the PLC & HMI stayed powered up did not see the reasoning on knocking the supply as you could not see which E-stop had been pressed even though there was alarms for them :confused: To be honest, found on other plant the AB drives failed far more often than any other drive.
 

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