PowerFlex 523 reversing without command

Every PowerFlex 523 and 525 I have received from AB has had this issue. If, using EtherNet/IP, I issue a Run Forward command, the motor will run forward for a second, reverse for a second, and then run forward as commanded. If I issue a Run Reverse command, the motor will spin in reverse, then forward, then continue in reverse. If I use the terminal block to issue commands, the same issue happens. I put a bit in the PLC to latch high if the command bit for reverse EVER goes high for the drives we didn't need to reverse. The bit never latched, but the drive would still reverse. A static tune was performed and the motor NP values were entered into the vfd.

Do you have anything programmed in the LOGIC group (page 100):
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/520-um001_-en-e.pdf

I have to say I have never encountered this. Is it possible you are getting noise or induced voltages on your control wires at a high enough amplitude to trigger the inputs?

I attached the parameter screenshots. The PF525's are installed in a cabinet with the 480V in Panduit and the Ethernet cable routed a good distance from the Panduit. The PF523's are mounted on a wall with the 230V running in conduit to a gutter below and the 24vdc run in a separate conduit to a different gutter. I tried SVC and V/HZ mode and the results are the same. If I use Reverse Disable, then I get a Forward, pause, Forward.

https://drive.google.com/file/d/0B748Jy3UvvAvc3N0UUpPR19LNHM/edit?usp=sharing
How about this instead of pictures.

Do you need to have flying start enabled

No, not really. They like to turn it off, take a peek, and then turn it back on quick.

The PF 525's don't have Flying Start enabled, but they do the exact same thing. I figured more people would have seen this. I have 24 PF 520 series vfd's out at 2 different plants and they ALL do this. I read off the modified parameters to the Rockwell Tech support guy and he said it was a fairly simple setup and it shouldn't behave this way.

I just did 10 (2 hp) with no problem. I started 40 (1 hp) in Feb / March with no problem . Can you post your program?

Have you called Tech Support on this?

What revision of firmware do the drive have installed

The PF 525 is firmware 2.002, controlled over Ethernet/IP only. The PF 523's are firmware rev 2.001. There is no program for the PF 523's, they are only controlled using the terminal block. The pictures above shows the non-default parameters for both drives. When we first had this problem back in March (the PF 525's) they had us upgrade the firmware. Yes tech support has been called and they are stumped, there have been some talks of "old stock" and "bad batch", but I don't believe that. I'll try to post a schematic of the simple PF523's.

TripleJ said:

The PF 525's don't have Flying Start enabled, but they do the exact same thing. I figured more people would have seen this. I have 24 PF 520 series vfd's out at 2 different plants and they ALL do this. I read off the modified parameters to the Rockwell Tech support guy and he said it was a fairly simple setup and it shouldn't behave this way.

Click to expand...

I agree with other responders...this is bizarre. When you DO find the solution, that would be good to post, as to inform others...even if its some really simple thing (they usually are, most times).
Good luck, and stay safe.

I don't know about the 5xx drives, but a PowerFlex 40 does have a parameter that prevents reverse operation..<P0095 from memory>>..so, while its not a fix, might it help to get past all of this???

My fist thought would be that this is related to EMI that is strong enough to bleed into the control signal wires. When you command a start, the drive pumps out its PWM into unshielded motor lead wiring, which pumps out a surge Of EMI, which gets into your digital input wires. The drive digital input circuitry has to filter it, but it gets overwhelmed for an instant, turns the drive command off or bleeds into the mP, then the filtering catches up and it goes back to normal.

The reversing is the odd man out in that, but is the drive actually reversing the motor, or is the MACHINE changing direction? Because if, let's say, this was belt driven that might explaing the appearance of reversal. For the first instant that you apply torque to a belt driven power transmission system, the belts stretches before the torque passes onto the load. If in that instant, you suddently REMOVE the torque, the belts will spring back, possibly reversing the load for a second, then when the drive reestablishes torque, the load goes forward again. Similar effect can apply to compressors, vacuum pumps and gravity dependent loads as well, (because we all know, gravity sucks) but you said the same phenomenon happens whether going Fwd or Rev, so those would be unlikely. But the fact that this happens going in either directing can be explained by belt stretch and spring back.

Here is what I would do. Take a drive and motor out of the system altogether, a set that you know for sure this happens on and put them on the bench, uncoupled to a load. Wire everything up just as you have it in the system and see if the problem repeats itself. If it does, get a piece of shielded VFD cable to go between the drive and motor and see if it cures it. If that works, there is your problem. If not, it's an issue deeper into the drive and AB needs to get involved.

If the problem is gone just from having removed the components, then you KNOW that it has something to do with the installation. So start putting things back in one at a time until the problem reveals itself, there is your effect.