Powerflex 700

dhthomas36

Member
D
Join Date
May 2011
Location
Pa
Posts
5
I been having a problem with our A-B Powerflex 700. It keeps faulting out on to different faults, one F-5 overvolage and the other is F-12 HW overcurrent. We changed the drive out and megger all the wires all looks good. Anyone have any ideas to pass along for me to try.
 
Welcome to the Forum !

Most of the time a drive fault like Overvoltage or Overcurrent doesn't result from a defective sensor or power component, but rather from an actual overvoltage or overcurrent condition.

The fact that you replaced the drive and are getting the same faults reinforces that probability.

Has this drive been running for a while ? Has anything in the application changed ?

Have you been able to monitor the incoming line voltage to see if it's going too high (one cause) or the bus voltage to see if it's going high because of regeneration from a decelerating load.
 
And while we're on the subject; it's my understanding that a "megger" can damage the power transistors of any semiconductor device like a VFD or soft-start. Be sure not to use it when the drive is still connected.
 
Income voltage is good and bus voltage is good. Allen Bradley told us to take the decel time up we did it faults out when we got over 170 feet per minute? We replaced the drive cause we was getting a encoder fault Allen Bradley came to our plant and could not find the problem so he changed out the drive and now we can't go over 170 feet per minute? we can run slower at 150 feet per minute it runs great but if we up it to 160 the amps start climbing and at 170 we run 10 feet at it faults out one time F-5 the next time F-12?
 
What kind of load is motor driving? what is load HP demand at 170 fpm? How does that compare to motor HP and VFD rated HP.

In other words are you overloading motor? Is all mechanical OK no worn bearings etc?

Dan Bentler
 
We been running for 5 years and this is the first problem with this. So I can say we are not overloading we have the right HP motor and drive cause we have 7 other plants set up like ours. We also called the company that built the machine and they say everything looks good no bad bearings or chain or sprocket no drag on nothing that they can tell.At 150 feet per minute i draw 27 amps on top and bottom at 160 I draw 45 on top on 29 on bottom at 170 it trips the VFD on F-5 or F-12. Had electric company hear yesterday to check motor, ground and brake on the motor even changed the drive reactor still get fault at 170 feet per minute.I'm lost
 
With encoder feedback, you are running a closed speed loop which requires setting the P, I, and maybe D gains. It could well be that these gains are set too high causing instability at the higher speeds.

I would suggest setting the drive to open loop volts/hz mode so it ignores the encoder and the loop tuning and see if you can run up to your full desired speed.

If that works ok, then you've either got an intermittent encoder or the loop gains need retuning as they are too hot.
 
Please correct me if I'm wrong but it sounds like you have two different motors and drives. One is driving a top "chain" and the other is driving a bottom "chain". In normal operation there is something between them. The other way I interpret this is you have a top and a bottom chain, each with their own motor but driven from a common drive. Or it could be something completely different and I'm interpretting your description incorrectly.

Don't look at the reported current. Look at the reported torque. Current is unidirectional; torque is bidiectional. You want to know which way they are pushing.

Keith
 
check that the paramaters are set corectly
Overcurrent or overvoltage can be a drive setting error.
If you copy the parameters from onr drive to the other you copy the error.
Also check the brake exitation - seperately wired - or not.
Raising the decel setting means - make the drive run on for longer before it stops. This can be incorrect if you have a brake in the system.
Is the brake timing controlled by a PLC or the VFD itself.
The brake may not be faulty but the timing maybe.
 
Worked at MDF board plant for awhile. When we started running heavy product, we overvolted our drives comming off accel and running down on decel every time we came out of the press. Are you running thicker foam then normal? we had to adjust accel and use braking resistors to cure the problem. only reared it's head when we went to heavy product.
 
Thanks all for your help and info, they found out it was the encoder.Put new one in runs like new. Thanks for all your time and answers.
 

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