VFD Fault need ideas

[BearB]

I have a VFD (AB Power Flex 70) operating a 5 hp motor controlling a progressive cavity pump pumping starch material. The system is set up to pump the material for a time then flush for a time after material is used from tank system cycles again to fill the storage tank. This system has been in service for several years without problems and no changes have been made. Several months ago the drive started kicking out on Fault 24 (following is from manual)- Description: Decel Inhibit-The Drive is following a commanded deceleration because it is attempting to limit bus voltage. Action: 1. verify input voltage is within drive spec limits. 2.verify system ground impedance follows proper grounding techniques. 3. Disable bus voltage regulation and or add dynamic brake resistor and/or extend deceleration time.
Changed the pump and had no problems for about 6 weeks. The problem has returned intermit. Increased the Deceleration rate in the drive from 3 seconds to 4 seconds, thought this help but after 3 days the intermit problem returned. Monitored incoming 480vac for 24 hours, looked ok however during this time the unit operated ok.
Any ideas would be appreciated.

 

[BearB]

Checked parameters early in problem, all ok.
No caps. or inductive switching around device.
DickDv I agree. I looked at the pump first then I posted for help and I temp. installed a iso. transformer 480-480 ahead of the drive yesterday when I posted the "follow up" post. It has been about 18 hours and no issues. I will report the findings when enough time passes to see a good or bad result. Thanks for all on this site I work for a small company without allot of Staff to discuss problems with. This site fills that gap.

 

[BearB]

Follow up to the VFD intermit fault. It has been 7 days of cont. operation since the transformer was installed without issue. I am getting the transformer installed perm. today on schedule maintenace. The VFD VDC Buss Voltage displayed on the drive is now showing around 635-655 before transformer it was around 680-685.

 

[itsmoked]

I think we have a weener!

Thanks for the come back, we all learn. Congrats.

Keith Cress
kcress -

http://www.flaminsystems.com