drives are dead again

We just recently installed a piece of equipment on our line and when the drive cabinet was brought back up at least 3 powerflex drives would not power up. We changed them out for new and no problems.
Then we installed a piece of equipinment on another line and when that cabinet was brought back up 4 dead powerflex 40 drives.

My question is if anyone has had a similar experience, and if so what did they find? Next is can the drives be repaired and at about what cost based on the problem? Reason for this is mainly personal as I am allowed all the broken items for my own personal use or whatever.

Thanks again

460V standard drives under 50hp are not usually worth fixing if the problem is in the drive itself, not the keypad or a detachable IO board.

You haven't asked us to help diagnose your problem here, but you definitely have one and it needs to be identified.

It would be easy to say, "just get rid of Allen-Bradley" but that is not likely a responsible response. AB makes reasonably reliable stuff and massive failure like this points to some other systemwide problem.

Good luck finding it. I would start by trying to determine in what way the drives failed.

I confused. Are these drives DOA out of the box, or were they working when the equipment was tested and then dead when installed at the site. It seems they should be under warranty shouldn't they?

I did read in the manual somewhere that if you have an ungrounded system where the phase to ground on any one leg is over 125% of the phase to phase voltage, they you need to remove common mode capacitors and MOV's.

I've smoked a few of these by hooking them up to a supply with a resistive grounded neutral without removing the common mode jumpers in the drive as described in the manual. Something worth checking out.

Drive

It depends on the problem with the drive on how diffacult it is to repair. It seems like the drives may have an input problem with them, blown fuse or input modules. I can repair at 1/2 the cost of a major repair facility like electrical south. Please contact me if you are interested.

Joe torres
1-708-601-0812

Long Shot

I once ran across this on a conveyor system. The drives where supposed to start at the same time so the control wiring for each drive was combined. Each drive creates its own control voltage so when ever the drives where powered up the drives would fry.

Like I said a long shot. Most people who work with drives knows this is a no no.

I use steering diodes with a 220 ohm resistor when paralling each drives control voltage output. Then via steering diodes in to the run fwd/rev inputs. This provides isolation drive to drive and a very simple control ckt.

What is your line voltage doing during the down time? I have seen several installations where their nominal 480V running voltage would rise to over 525V when no equipment was running. Many new generation drives suitable for 400-480V don't like voltages above 500V.

John Hawkins said:

I use steering diodes with a 220 ohm resistor when paralling each drives control voltage output. Then via steering diodes in to the run fwd/rev inputs. This provides isolation drive to drive and a very simple control ckt.

Click to expand...

Never thought of doing it that way, I usually just use Ice Cube relays. I usually buy the ones with the buttons so I can manually fire the realys from the cabinet. Techs like that so they can individually start a drive for trouble shooting.

No, they are known working drives until the cabint was down for a few days. And not all of them died. Only a few and in no particular order. They are all started one by one and on softstarts at that. I will take more of the posts made in this thread and look more into some of your questions to me.


Thanks alot

ChuckM said:

I confused. Are these drives DOA out of the box, or were they working when the equipment was tested and then dead when installed at the site. It seems they should be under warranty shouldn't they?

Click to expand...

plcnewbie said:

No, they are known working drives until the cabint was down for a few days. And not all of them died. Only a few and in no particular order. They are all started one by one and on softstarts at that. I will take more of the posts made in this thread and look more into some of your questions to me.


Thanks alot

Click to expand...

How are the softstarts wired with the VFDs? I've never heard or seen a configuration like that. My first thought is that its not compatible; one or the other but not both.

Some AB drives actually have an SCR DC drive type front end. This is used to ramp the DC voltage up to the DC bus and smoothly charge the cap bank.

You really need to get these drives analyzed by a shop for the actual falure. Finding out why the drives failed can then be used to prevent future failures.

Are these drives using a common DC power supply? I have seen single phasing thru the DC supply cause drive failures.

plcnewbie said:

No, they are known working drives until the cabint was down for a few days. And not all of them died. Only a few and in no particular order.

Click to expand...

I am not familiar with AB drives but here's my tip:

Are the defected drives 1 fase inverters? If so are the damaged drives connected to the same fase?

We had problems with some drives in the past. Later we found that the drives where all on the same fase. The problem was the external power supply of the cabinet blowing up the drives on that fase.

This is a major AB problem

I too have had the same problem. I have some cabinets with up to 15 Powerflex 4 drives in them. When I shut down the cabinet, all was working fine. Upon powerup, 2 or 3 of the drives are dead. 480 volt power to them but NOTHING (no display, no worky!) Here is the interesting part of this problem. I have approximately 50 of this drives in many different configurations and I am now regularly experiencing drive failures. For the first 3 years, no problems at all, but now, there is definately something wrong. At first, the AB drive techs said it was all my installation (improper clearance -even though the book says zero clearance, too hot of an environment - cabinets measure about 105 degrees F in the middle of summer, too long of motor leads - some are as short as 10 feet, etc. etc. etc.) I have sent AB many of these failed drives in the past.

I finally got in touch with a tech there that said he "thinks" that there is a design problem with an undersized resistor. That was just in the past couple of days. I will know more about this in the next couple of weeks since I now have 2 more to send to him.

*********** RANT ***************
I have some paper work from one the drive techs - before he ever saw one of the drives - that pretty much blames the problem on poor installation. I really don't understand why some people tend to blame the victim without all the facts. I just hate dealing with some customer support and all I get is it must be an installation problem because you are the only one complaining. If and when that shakes out to be a design fault, I feel like I should push the attitude of the "highly trained drive tech" (his words) down his throat. At the least, I will call him up and said "I told you so jerk!!!!!"

************ RANT OFF ************

As a final note, if you want to keep in touch with me via PM or email (PM me for my email address) I will let you know how all this ends. I pretty sure that with approximately 10 failed drives this year (all in different installs), something big is wrong with the PF4 (and PF40).