PowerFlex 523 reversing without command

[Jwillis]

Try changing that start reference 3 and speed reference 3 to ethernet I/P. The drive acquires the start and speed reference from 3 then 2 then 1. You can select either 2 or 1 for the keypad control.

 

[TripleJ]

I am setting up a PF 523 (a new one, as the installed ones are in another state) with the same setup as it is installed, except no load (motor only). The motor cables we use are shielded vfd cable, with just enough wire exposed to land on four terminals. as I recall, we didn't have this issue while testing with our unloaded motor.
As for the direction change, the front of the drive does show the reversed command as a blip. I'm certain the drive is intentionally reversing the motor, but I need to narrow down why. I'm going to try putting control wires close to the input and output leads at different angles to try to reproduce or eliminate this problem (depending on the initial result of the test). Thank you for all of your replies, and yes, I will CERTAINLY post the fix.

 

[TripleJ]

I just rigged up a PF 523 using the same wiring as it is installed. The motor was uncoupled (no load) and did NOT do the fwd-rev-fwd or rev-fwd-rev. I wrapped the control wires around the Line leads - No problems. I wrapped them around the output cable - no problems. I did a static autotune - no problems. I lowered the FLA setting to half of the actual amps the vfd was putting out - no problems. It's either only a problem when loaded, or (and I really doubt this) a batch problem. I'm going to put a load on it now. The test rig was not flashed, it's still running 1.001.

 

[kamenges]

I had a velocity related issue with several PF525 drives a while back. While my issue is not the same as yours I might be able to see where it could cause an issue like yours. I was set up to run in sensorless vector mode.

In my case I couldn't get the drive to stop moving the motor. If I issued a zero speed command the motor would continue to move in the last direction it was moving. If I swapped the direction bit it would change direction but continue to creep.

In my case the the slip compensation function was providing too much frequency offset and would prevent the axis from stopping. Apparently there is no way to disable this so you have to trick it. Slip comp is calculated relative to the slip frequency, which itself is calculated based on synchronous RPM relative to nameplate RPM. If you want to disable slip comp you need to set the nameplate RPM equal to synchronous RPM.

I don't know if this will make a difference for you but when you said this only seems to happen to a loaded axis it make me remember my issue. And it doesn't take much to try this.

Keith

 

[TripleJ]

Thanks, Keith. I will try changing the NP rpm to synchronous rpm. Something has to work eventually.

 

[GTUnit]

jraef's answer was excellent.
I seriously doubt there is a hardware/firmware problem on all your drives.
It is most likely an issue with the application.

Like he said run the drive/motor on a bench.
Off a different power feed then your process, far away from everything.
If it works correctly, which it appears that it does, then your problem is somewhere in the application/field.

I did Ethernet control of 525's and it was a PITA.
You should post the Ethernet control code for review.

 

[TripleJ]

I guess it's worth stating again, one set of drives are Ethernet controlled, but the pf 523's are not. Both of them exhibit the fwd-rev-fwd. The 523's are terminal controlled, 2-wire with reverse. We, too, had thought it was an ethernet issue, until we installed the 523's without ethernet and the same thing happened.

 

[Psymon]

I've seen something similar to this when working on winders. Is there a PID enabled in the drive that could be causing it to reverse?

 

[JeffKiper]

Did you ever get these working?

 

[TripleJ]

I had the opportunity to visit the site that has the PF 525's on ethernet/ip the other day. I used CCW to log the drives (at the superfast rate of a sample a second) and got some interesting data. I'm going to try to post my logs shortly. I found I can minimize the appearance of the reversing, but not the actual reversing.

 

[TripleJ]

PF 525 Logs

I attached an Excel spreadsheet with 3 different logs on three different sheets. The commands are coming from Ethernet/IP, so the Command word is pretty worthless, but you can see the drive status changing.

 

[Firejo]

Is it possible that the motors are wired wrong? Are they the same motors (make, model, etc…) in all cases? Have you tried a different motor? Just some stuff that comes to mind.

 

[kamenges]

How did you minimize the reversing?

 

[chud]

Sorry I dont know this drive but experienced something similiar with an ABB drive
How does this drive preform a running motor id, or autotune?
Could it be that the drive is setup to do an autotune at startup?

 

[osmanmom]

other info,

http://www.staro.co.za/attachments/article/36/PN_2014-06-001.pdf