Jiggadoo

PF527 Bus undervoltage user limit

5 posts in this topic

Posted (edited)

I had axis fault, which stopped the PF527. Only way to go on was to switch power off and on again.

Checking the faults&alarms, I find out that the reason was Bus Undervoltage user limit. This made 'Immediate Stop' for the PF527. Looking at the parameters, I can not find any parameter for this. In the manual it is said

'DC Bus voltage level is below user defined limit given by Bus Undervoltage User Limit, or device defined limit if the user limit attribute is not supported.'

What does it mean?  Is there parameter for this limit?

Checking the AXIS_CIP_DRIVE tag parameters, DCBusVoltage is not showing anything, why is that? => Reason found, not marked in 'Axis properties' Cyclic Parameters page

Edited by Jiggadoo

Share this post


Link to post
Share on other sites

I'm not an expert on this drive but I do know that most PowerFlex drives do not allow you to adjust the bus voltage thresholds. You can only program (on some drives) what happens when a bus over- or under-voltage condition occurs.

As you likely already know, the bus voltage will typically go low for one of two reasons:

  1. The incoming power is low
  2. There's a problem with the axis motor or wiring that's pulling the voltage down.

I've attached a link to the PF527 user manual, and Technical Specifications on bus voltage voltages can be found in Appendix A on page 137.

I would check the specs against your specific drive, check the actual bus voltage with a meter at the DC+ and DC- terminals on the power terminal, and work from there.

 https://lvmcc-pubs.rockwellautomation.com/pubs/520-UM002C-EN-E.PDF

 

1 person likes this

Share this post


Link to post
Share on other sites

Powerflex 750, 755T, 700S and motion drives allow a user to adjust undervoltage threshold. For the 527, go to the module properties then power then advanced. You can set the limit there. Monitor the dc bus of the drive and see if it’s stable. If not, there may be something wrong with the drive. If it is stable. Look at incoming power

1 person likes this

Share this post


Link to post
Share on other sites

Thanks for helping. You gave me good information.

Feeding power to the PF527 is coming throught the energy transmission chain, I need to check this cable and the connections. Also connection to the motor too.

Motor is used in a conveyor, there is quit fast ramp 'running speed during 1 sec'. I have not seen any problems with that before, I think this is still fine.

Undervoltage limit seems to be 65%, I think this is fine. I have not changed that, it is in a default value.

Share this post


Link to post
Share on other sites

Thanks @VFD Guy! I've never needed to adjust or even look at those settings in an AC drive and only knew (as I said) that most drives don't allow it.

Point of interest: though DC drives are a bit of dying art, the Allen Bradley PowerFlex DC drive allow line voltage max/min threshold settings as part of its normal parameters settings. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now