Isuue with power flex drive (753)

Hey guys,
I need urgent assistance regarding an issue that I am facing with power flex 753 drive, Rockwell Automation installed in one machines here.The HIM unit of the drive was not starting up & hence I had suspected the power interface card to be faulty.
Subsequently , I had replaced the card & when I switched on the power the HIM unit had started working,but as soon as I issued a start command to the drive the IGBT burst open !!& the entire unit smoked out.

I am at loss to understand as to what happened??I had checked the connections multiple times after installing the card & didnt find anything wrong

Pls help!

I'm not sure where parameters are stored...

Maybe, are parameters stored in HMI?? If you have replaced the HMI, you have replaced the correct parameters with new ones, so....

inJGS said:

I'm not sure where parameters are stored...

Maybe, are parameters stored in HMI?? If you have replaced the HMI, you have replaced the correct parameters with new ones, so....

Click to expand...

The HMI was the same.But how does the parameters stored in the HMI be responsible for a event like this ??.I am supposing the IGBTs burnt out because of short circuit that might have happened due to wrong firing signals.

Getting a little confused now!

rejoe.koshy said:

The HMI was the same.But how does the parameters stored in the HMI be responsible for a event like this ??.I am supposing the IGBTs burnt out because of short circuit that might have happened due to wrong firing signals.

Getting a little confused now!

Click to expand...

I was rechecking the HMI of the drive & found that the parameters in it are in default state....Could indicate anything as to why the drive failed??

Pls help!

There is nothing in the parameters that could make an IGBT burst. You had a component failure. Most likely from the description of your events, you have a bad capacitor and the resulting high bus ripple was first affecting the control board, but eventually caused a misfire in the IGBTs and the rupture you described.

As to why the cap failed, you would need to know the history of the drive. A common cause is that the drive sat unpowered on a shelf for a couple of years and the capacitors "de-formed" where the oxide layer they require to function became reabsorbed into the electrolyte. There is a procedure you need to perform called "capacitor reforming" that is recommended whenever a drive has been unpowered for over 1 year. If you don't do it, just applying power will burn through the layers in the capacitor and fry it. From there it's only a matter of time before you start losing transistors.

jraef said:

There is a procedure you need to perform called "capacitor reforming" that is recommended whenever a drive has been unpowered for over 1 year. If you don't do it, just applying power will burn through the layers in the capacitor and fry it. From there it's only a matter of time before you start losing transistors.

Click to expand...

Does this apply to all VFDs or only Allen Bradleys? I have two shelves full of Altivars that have been in storage for at least 3 years.

I'm planning on putting "reform caps before applying power" sticky notes on all of them. Because there is no way I'll remember that in 2-3 years.

It applies to all VFDs. All of them have (or should have) information about this and how to do it in their technical support documentation. Just search for "capacitor reforming procedure" with your favorite search engine. You will see that most of the hits will be from VFD mfrs.

Thank you for the tip. I am sure one or two of them would have fried before I figured out what I was doing wrong.

Thanks guys, thanks a lot..

I was totally unaware of this procedure.The drive was in an unpowered state for over 2 yrs till I started running a few weeks back...

Does this concept hold good for all electrolytic capacitors for example those found on control cards?? If so, then I need to worry about several control cards which are stocked for few years now..!!