PF525 Head Scratcher

[Puddle]

The screenshot is showing Fault code 4, which is undervoltage. Not sure if that's just been retained from the last time it powered down or if it's an active fault.

I've had a problem with Powerflex drives before where the whole panel has been turned off but the drive hasn't discharged fully and it's retained F004 on the screen, which stops it from running.

[Jackllx]

Originally Posted by Puddle

The screenshot is showing Fault code 4, which is undervoltage. Not sure if that's just been retained from the last time it powered down or if it's an active fault.

I've had a problem with Powerflex drives before where the whole panel has been turned off but the drive hasn't discharged fully and it's retained F004 on the screen, which stops it from running.

The drive thinks that it's running.



This looks like a faulty drive to me.



This being remote support is difficult, because you are relying on people telling you things, I've been caught out on this a few times, travelled to site only to find they didn't do the first thing I told them to do!

[iggy]

We have had several of the 20hp PF523 do the same thing, replace the drive.
The drives were sent off to do an analysis and have not heard back yet.

[GaryS]

Just a thought
I noticed before that the buss voltage was low
At the time I didn’t know what the fault 4 was
Somebody here said it was low buss voltage

It’s odd for 2 VFD’s with the exact same problem showing the exact same fault makes me wonder
Is there a line contactor in front of the VFD or a breaker inline
Check that the contactor or breaker is closing correctly (all 3 phases ) one may not be making full connection
A bad connection on one leg may cause the buss voltage to stay low the control may read it as high enough to run but too low to run correctly. I think that Power Flex drives use 2 incoming phases to power the controls if the third leg was low or missing I don’t know what would happen.
I have seen other drives run at reduced power with a single phase line input
I don’t know if they even check for incoming phase loss I know some drives don’t check or care.
And with some driver they give you the option to disable incoming phase loss fault
It think it would be worth it to check it out

[slp530]

I've had a similar fault with a low DC bus voltage, I found one of the phases going through the input line filter had failed

[IanM8040]

The bus voltage wouldn't be low if the set voltage was 460v

460v x 1.414 gives pretty close to the output of 456v.

If it's supposed to be 480v, then I'd say it's low. but that doesn't appear to be the case if that's the setting it's at.





some testing you cold do. aside from double checking all the parameters for the motor nameplate, and ensuring those are accurate. and double checking incoming and outgoing drive voltage with a meter.

go to parameter 495 - Drive OL Mode, and set it to 0 (disabled). and then test again, see if it's automatically limiting itself due to an overload condition on ramp up. Just make sure to change it back once it's tested.

[IanM8040]

Originally Posted by GaryS

Just a thought
I noticed before that the buss voltage was low
At the time I didn’t know what the fault 4 was
Somebody here said it was low buss voltage

It’s odd for 2 VFD’s with the exact same problem showing the exact same fault makes me wonder
Is there a line contactor in front of the VFD or a breaker inline
Check that the contactor or breaker is closing correctly (all 3 phases ) one may not be making full connection
A bad connection on one leg may cause the buss voltage to stay low the control may read it as high enough to run but too low to run correctly. I think that Power Flex drives use 2 incoming phases to power the controls if the third leg was low or missing I don’t know what would happen.
I have seen other drives run at reduced power with a single phase line input
I don’t know if they even check for incoming phase loss I know some drives don’t check or care.
And with some driver they give you the option to disable incoming phase loss fault
It think it would be worth it to check it out

it's a definitely good thing to check and ensure that the wiring is accurate.





Story time -

I was helping support over the phone a customer who had a bad PF527 drive, and they attempted to replace it. it was being run as a motion axis in the program, and was using safe torque off over ethernet, etc... all the things.

every time it was tried to run it would fault for overload. Well the first thing up was to tell them to take the U-V-W leads off and check the motor and ensure it's spinning freely (if possible), do a quick check of resistance on the motor, make sure it's not bad... I was told it was good to go, and they put it back on.

I was remote connected in and attempting everything I could to see why this was failing. nothing had changed that we knew of, and nothing programmatically changed so it made no sense at all. We even called up and double remote supported with rockwell over the phone and their guy couldn't get to the bottom of it.

Until Finally, they had another drive they wanted to try, and I said of course, go ahead and throw it in, and what do you know, over the phone I can hear ... "Hey, who hooked this up!?!? they wired it up backwards!".


for almost 2 days of support time, they had a "throw away" tech doing the hand work, while the supervisor was relaying the info for troubleshooting, and he was relaying it back through. Apparently he had hooked up the L1-L2-L3 and U-V-W backwards, and it didn't blow the drive up...It didn't even fault until you tried to run!!!!!

They swapped the leads around and it took off no problem. After being told to check the connections multiple times, and having them remove them multiple times, and not a single time did anyone realize they had wired it wrong because it powered up every time...

[JankyPLC]

Stories like these make me think those old folks might have been onto something with a simple contactor.

Troubleshot a different drive one time faulting on OL when trying to run. Voltages, wiring etc all checked fine with drive idle... Then checked input voltage while trying to run. One phase would dip to almost nothing every time. Other two were fine. Bad contact in the MCB was creating enough resistance that under load the voltage on that phase would drop enough to (I'm guessing? cause the DC Bus voltage to dip, or overload the other two phases rectification enough to) cause the drive to fault on OL, but not enough to cause weird voltage readings with no current draw. Never forget to check that now.

As for this drive, found a new one(miracle in itself), swapped in, works perfect! In the end, original drive died, and a bad used replacement part was the diagnosis.

[Nova5]

Originally Posted by IanM8040

it's a definitely good thing to check and ensure that the wiring is accurate.


......
They swapped the leads around and it took off no problem. After being told to check the connections multiple times, and having them remove them multiple times, and not a single time did anyone realize they had wired it wrong because it powered up every time...

I had never checked nor imagined you could power it up from the output side of the VFD.

[alan_505]

Some drives will power up, some will let the magic smoke out.

[ganutenator]

I know for a fact if you hook up Line voltage to the Motor leads on a Schneider drive it will make a nice boom.
I'm actually waiting for a bad drive so I can demonstrate this to the new guys at work.

[ganutenator]

shout out to Ken Roach. You are the shiz dizzle.
I hope you never burn out.
Love your posts.
I haven't worked w/ AB in decades, but kinda almost wishing I was w/ your awesome support.

[jraef]

Check that the contactor or breaker is closing correctly (all 3 phases ) one may not be making full connection

A-B drives do not have phase loss detection based upon actual phase voltages, they only cares about DC bus ripple. So if a line contactor or breaker was not conducting through one phase, the VFD would not know or care until the load current increased enough to cause bus ripple.

Now if there is a LOAD contactor, i.e. a safety contactor and it is open, then the VFD would not know right away, if ever. If the drive was in SVC mode it would eventually throw a fault on "Load Loss" if programmed as such (check parameters A490 and 491 to see if it is enabled). But if it is in V/Hz mode, even with those enabled it may not know or care.

Barring that though, this sounds like a bad power module. So the thing is, TWO of them in the same installation? That sounds like maybe a problem in the motor or circuit taking out the transistors too fast for the VFD to detect it. That can happen from a phase to phase short in the windings or the motor leads. It might be high resistance enough that it doesn't show up easily when connected across-the-line, but it's enough to take out the transistors. Before hooking up a new drive, I would be doing a lot of testing on that motor with a MEGGER, not just a DMM. But also keep in mind that a basic megger test is usually just looking for phase to ground faults, you have to do a different test to find phase to phase. It's not simple.

[seth350]

Just sharing my experience with a 7.5HP 525.
We upgraded from PF40s and did motor/gearbox upgrade.
First power up, set the accel/decel as needed, SVC, then started.
Drive started, but motor did not move. Checked speed setpoint, it was 60Hz.
Tried again, no rotation. Checked amps, very little.
I ran autotune, tried again, the motor ran.

[Nova5]

Originally Posted by alan_505

Some drives will power up, some will let the magic smoke out.

I would fully expect the latter.