Allen Bradley Power Flex 40 Issues

[Phil Corso]

Aelectricalman...

Have you asked your Utility Company if they do any switching in their system at about the time(s) you experienced your VFD trips?

Regards, Phil Corso

 

[petersonra]

Bob,
Did you read the attached report I sent earlier?

I saw it after you mentioned it and went and read it. It seems to me like the problem was that the plant did not provide protection from overvoltage for the rectifier modules. They seem unusually sensitive to overvoltage. one would have thought the manufacturer of the rectifier modules would have known they were unusually sensitive to overvoltage. 509V is not all that high compared to the nominal 480V.

VFDs almost always include a trip on overvoltage. I think if an overvoltage occured it would have tripped on that rather than on something to do with the safe off boards. I have run across a fair number of VFDs that have tripped on overvoltage.

I don't see how a DC voltage on the MV side of the xfmr somehow makes it over to the 480V side.

 

[ptonsparky]

We had a customer with problems after a large PFC was installed. Voltage on entire system went up as it was switched on, just like the math said it would. We had POCO change their taps and all was good again.

Will it help you? Don't know.

 

[ghostbuster]

In response to one of the group's request w.r.t. power factor/cap banks and electrical interference generated:

Here is an attached article we published and presented back in 1998

Enjoy

 

[ptonsparky]

In response to one of the group's request w.r.t. power factor/cap banks and electrical interference generated:

Here is an attached article we published and presented back in 1998

Enjoy

:thumbsup:

 

[ATSman]

In response to one of the group's request w.r.t. power factor/cap banks and electrical interference generated:

Here is an attached article we published and presented back in 1998

Enjoy

Ghostbuster (love the name! )
Excellent report and PQ analysis. With reference to my earlier attached report it was concluded that the root cause of the damage to the 37 rectifier modules was caused by a FAULTED PFCCB through a striking ground fault on an ungrounded 12KV Delta POCO 3-phase power line. And yes, these transient high voltages (6 to 12X nominal) can and will reflect back through the stepdown power transformer to the facility's 480V loads. It was learned later that the AC failure alarm damage to the modules (estimated to be around $260,000 US) was caused by blown 3-phase input fuses internal to the modules.

 

[ATSman]

I saw it after you mentioned it and went and read it. It seems to me like the problem was that the plant did not provide protection from overvoltage for the rectifier modules. They seem unusually sensitive to overvoltage. one would have thought the manufacturer of the rectifier modules would have known they were unusually sensitive to overvoltage. 509V is not all that high compared to the nominal 480V.

VFDs almost always include a trip on overvoltage. I think if an overvoltage occured it would have tripped on that rather than on something to do with the safe off boards. I have run across a fair number of VFDs that have tripped on overvoltage.

I don't see how a DC voltage on the MV side of the xfmr somehow makes it over to the 480V side.

Bob,
The 509V was read from the diagnostic history of a Cutler-Hammer IQ power meter which records only steady state voltage, not transients like a PQ meter. Unfortunately, the facility had no PQ equipment installed to capture the waveform. Also, a striking DC voltage is an AC voltage and will pass thru a xfmr.
See my comments to Ghostbuster.

 

[ghostbuster]

Fluke has an interesting PQ /CAP Study

Here is the link

http://support.fluke.com/find-sales/Download/Asset/2584575_6115_ENG_B_W.PDF

Enjoy

 

[Jraef]

All very interesting and very informative.

It all has nothing to do with the OP however. The speculation that this had anything to do with the recent PFC system is not likely germane, the fault he is getting is specifically pertaining to a machine safety control board accessory that he has (supposedly, although he never answered) installed in the drives, and they are giving a fault indication at very precise time events exactly 12 hours apart. The "Fault" is also, by the way, not necessarily really an error. In a machine safety circuit if you open the safety input to purposely shut down the drive output, called "Safe Torque Off", it is because the Safety Relay specifically TOLD the drive to do that, and it is registered as a "Fault" because per safety Protocols, engaging it requires a process of someone trained in the proper safety procedures to purposefully reset the safety Lockout. So in the VFD, this is accomplished by forcing someone to reset it by treating it as if it were any other kind of fault.

 

[GoldDigger]

All very interesting and very informative.

It all has nothing to do with the OP however. The speculation that this had anything to do with the recent PFC system is not likely germane, the fault he is getting is specifically pertaining to a machine safety control board accessory that he has (supposedly, although he never answered) installed in the drives, and they are giving a fault indication at very precise time events exactly 12 hours apart. The "Fault" is also, by the way, not necessarily really an error. In a machine safety circuit if you open the safety input to purposely shut down the drive output, called "Safe Torque Off", it is because the Safety Relay specifically TOLD the drive to do that, and it is registered as a "Fault" because per safety Protocols, engaging it requires a process of someone trained in the proper safety procedures to purposefully reset the safety Lockout. So in the VFD, this is accomplished by forcing someone to reset it by treating it as if it were any other kind of fault.

Thanks for that clarification.
It was not clear from the OP's posts whether the drive just required resetting to clear the fault or whether there was actual hardware damage.

Suddenly there is a slew of them going bad.

If in fact the fault is resettable, then it does look like there is something going on in the operation of the machines.

 

[petersonra]

this particular fault has nothing to do with opening up the safety input. it means the thing has not been wired correctly. the only way to clear the fault is to wire it correctly under normal conditions.

 

[petersonra]

It seems to me that the OP should contact AB tech support and see if they have anything to add to this. There may be a known issue and a work around.

 

[aelectricalman]

It does sound like it might be a tap change or a PFC system that is switched in and out by POCO at particular predictable, scheduled times.

Golddigger. We worked with the PoCo and had MV90 meters installed on the lines. We found that at nighttime (on the weekends) the voltage was in excess of 508 Volts . We found that the problem was a pin broke, disengaging the gears from the shaft on the LTC's at the substation. You were exactly right. It was replaced and the issue has went away. I want to thank everyone for your comments and insight into your personal experiences. This really helped me understand potential issues with substations and industrial facilities a little more.