Powerflex 4 Drives-Are they sensitive to Power Issues

[Rob S.]

We have several PowerFlex 4 drives around the plant.We had a
planned outage that the power company was going switch over to
another feed , after this switchover we had a lower voltage of
424 vac. After this we had several drives go out, no display, nothing. Of the causes possible ,which is the most possible?

1. The low voltage
2. Possibly the power company closing the 3 fuses one at a time,
about 20 seconds apart,causing a single phase condition.

We have Square D TVSS units on all the feeds.

Thanks in advance,

 

[yazco]

cause is of use changes

 

[TConnolly]

Contact your utility company immediately about re-tapping your transformer. Make sure you make it clear you are not happy. They should have performed a check for you and made the tap changes before they authorizd you to turn the power back on. This is just plain shoddy, sloppy, lazy, and irresponsible on the part of the power company workers.

 

[Thomas]

When did you get the drives?

Power Flex 4 drives were not at first very robust. For a few years these drives would simply fail to come back to life after a power outage (lockout....). I understand that there perhaps were some problems with capacitors used early on.

For the last year or so we have not had this problem. Rockwell seems to have resolved it.

 

[jstolaruk]

Are you using a A-B line reactor on the inputs? SOP for me and VFDs anymore.

 

[monkeyhead]

Contact Allen Bradley tech support... They had some component supply problems with some of the PowerFlex 4 drives. I'm not at my work computer so I don't have the info, but they have a certain date, that if manufactured before, you will see this problem on. I seem to be remembering Oct 2003 or 2004, but my memory could be waaaaay off.

We sent several back and AB fixed them and promptly returned them.

All ours died the same way... Shut down a working machine for scheduled maintenance. Then after the locks are all taken off and everything is powered on, the drive won't turn on.

 

[allscott]

Contact your utility company immediately about re-tapping your transformer. Make sure you make it clear you are not happy. They should have performed a check for you and made the tap changes before they authorizd you to turn the power back on. This is just plain shoddy, sloppy, lazy, and irresponsible on the part of the power company workers.

Agreed, but in a situation like this I would have tripped the mains at the PDC's and verified voltage and rotation before re energizing the plant. How big of a disaster could it be if a bunch of pumps started rotating backwards on re energization.

 

[monkeyhead]

The tale-tell sign is that you've got power coming into the drive, and the dc bus is charged to approximately 650VDC, but the display won't come on. One of the components on the low voltage power supply internal to the drive has failed and is a known issue.

You can check by taking a voltage reading across the braking resistor terminals to see if the DC bus is charged.

I don't think single phasing the incoming power would have fried the drive. It may have caused one of several faults on the PowerFlex4, but frying it is unlikely. I've actually seen several other brands of VFD that have no problems losing a phase.

One K&B Electronics drive (KBAC-45) I dealt was running off a single phase. The DC bus would discharge to quickly causing an under voltage fault after it ran for a while, but the motor would run until the fault occurred.