I have just started a new job and have been given a problem to overcome. After running the same process without any problems for about 2 years, the AB Powerflex 4 drives began catching fire. The drives have been catching fire on the average of about 1.5 per week for the last six months. There are six drives (3 each in each of two enclosures) and any one of the six may decide to burn up. The 480V input and 480V output circuits seem to be unaffected by the fire. The fire is usually confined to a "logic"(?) board located just under the board containing the control terminals. I have looked on the AB website, but can't find any reference to drives catching fire. We already have isolation transformers on the infeed power and line reactors on the outfeed side. We are using shielded cable on the outfeed. Would be interested to know if anyone else has had this problem, and what they did to correct it.

 

This is covered in the manual. You need to remove a mov jumper when using these drives on ungrounded power.

 

Carl, for safety and liability sake, you really need to talk directly to Rockwell about this. There is something seriously wrong. It may be entirely accidental that this is taking out the drives. It could start blowing transformers, or shorting out other components. Someone may be injured. PLEASE contact qualified technical support.

Go here: http://support.rockwellautomation.com/ for the phone numbers.

Walt Boyes
www.waltboyes.com
[email protected]
630-639-7090

 

Since the guy says he has an isolation transformer, which most are a delta to wye-grounded, wouldn't a better solution or suggestion be to tell him to check the grounding of the system vs. disable a protection device (MOV) in the drive?

 

I believe we have resolved the flaming VFD issue. After placing all the drives outside the cabinet to minimize damage to the interior components, motor starter contactors began catching fire, instead. Inspection of the motor starters revealed that almost all the damage to them was on the exterior. We then mounted a security camera to determine the exact cause of the problem. The security tape will be used as evidence to procecute the operator of the machine.

 

Hi,

A lesson to all service engineers; don't assume anything!

Marc Sinclair

 

Hi,

Will you be able to give me more details about the type of load that you are running with the drives? Sounds to me like you are boosting your DC bus a bit high when you are running.

Does your load have a high ennuresure?
If it is possible, will you be able to mail me the .dno files of the parameters that you pulled off with Drive Executive?

Hope to hear from you soon.

 

Ensure that the drives are supplied power from a grounded wye (not delta, not high impedance ground) or ensure that configuration jumpers have been removed from the MOV circuits.

See AB doucmentation. Page 1-11 of Publication 20A-UM001L-EN-P – April, 2006 Power Flex 70 User Manual. Similar for Power Flex 700.

Bill Code

 

In reply to O'Ronan Bougard: If you read Mr. England's reply on the 14th of March 2007 at 11:55 pm, you will see that he provides a fairly clear description of the source of the problem and how it was resolved.

 

Was about to ask what "ennuresure" was - did a Google search on it, and it came up blank - then spoke it out aloud. I believe the word is 'inertia'. In any event, remember reading Carl later found the problem had something to do with an individual setting fire to the drives, at least, that was the inference. http://www.control.com/thread/1026232237