Page 1 of 3 123 LastLast
Results 1 to 10 of 23

Thread: Danger, Will Robinson. A VFD Story

  1. #1
    Join Date
    Jul 2009
    Location
    Waukesha, WI
    Posts
    1,311

    Default Danger, Will Robinson. A VFD Story

    Well, the title might be click bait, but reading this could save you some money and singed eyebrows.

    I was helping to to put the finishing mechanical and electrical touches on a friend's new shop built 72" belt grinder. After wiring the ABB NOS VFD, circa 2005, and carefully checking all the electrical connections, the drive was powered up.

    The motor rotation was wrong, so a quick trip into the parameters to reverse the motor and all was well. ABB's menu system is vastly superior to the menus and book that came with my Microtronics and my Huanyang drives. It spun-up quietly and we ran the speed up and down for a few minutes before stopping it via the front panel control marked 'Stop'

    What follows isn't so pretty. The main power was disconnected and some minor adjustments were done to the belt drive. Plugging the power cable in resulted in a bang, a shower of smoke and sparks and left the inside of the case and part of the outside pretty much coated with the remains of the capacitors that used to be inside the drive... Not sure how much, but a great part of their mass escaped as magic smoke... never to return. The only thing left on the circuit boards were a few toroids. Everything else was vaporized.

    So at the near-end of the installation manual, page 286 out of 312 total pages, there is one lonely paragraph of 64 words entitled 'Capacitors', subtitled 'Reforming' that refers you to the manufacturers web site to find the information on reforming the capacitors...

    Now here I will interject my own thoughts on the manual's paragraph. If this information is so important, which is certainly my retrospective judgement, the reforming information could have easily been included in the nice manual. Had this information even been vaguely referenced near the beginning I would have been a lot happier.

    I am not ignorant of reforming capacitors, a common practice in antique electronics resurrection, but I certainly would have liked a heads-up in the manual. If it was important enough to mention at all, I would have appreciated a little heads up before the magic smoke leaked out.

    This part is for my own education. Have any of you electrical professionals seen such a reforming warning included with any equipment you have installed? I don't remember seeing it referenced here on this forum, so let this post be a warning to any purchasers of older NOS or used equipment. If I missed said reference, my bad...

    Capacitors have a great ability to inflict damage. I used to like capacitors...
    paul
    ARS W9PCS

    Esto Vigilans

    Remember, just because you can doesn't mean you should...
    but you may have to

  2. #2
    Join Date
    Oct 2005
    Location
    British Columbia
    Posts
    5,961

    Default

    Thanks for the info Paul, looks like I'll have to re-read my ABB Powerflex manual.
    Can't say I recall the cap reforming procedure but Ill have to find it an have a look. I quite often disconnect the power input to the vfd but seeing as how it's been almost 15 years in service I've probably been spared. Just wondering if there were some other factors involved. Not necessarily the installation but a fault within the vfd itself?
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories

  3. #3
    Join Date
    Jul 2006
    Location
    Dracut, Massachusetts
    Posts
    1,744

    Default

    I know about reforming capacitors, but have not heard specific warnings about such with VFD's. Though I suppose it makes sense. I've designed stuff using them and installed quite a few in my work but don't ever recall a notice concerning this. As you know, this is typically an issue with things that have sat, nu-powered for very long periods of time which it sounds like was the case here. I'm a bit surprised that it did not happen as soon as you powered the thing up for the first time.

    Did the ABB manual describe the process they recommend to reform the caps in their VFD's?

    In any case, thanks for mentioning this.

  4. #4
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    2,056

    Default

    Quote Originally Posted by Willy View Post
    Thanks for the info Paul, looks like I'll have to re-read my ABB Powerflex manual.
    Can't say I recall the cap reforming procedure but Ill have to find it an have a look. I quite often disconnect the power input to the vfd but seeing as how it's been almost 15 years in service I've probably been spared. Just wondering if there were some other factors involved. Not necessarily the installation but a fault within the vfd itself?
    If the caps blow up they are probably the orginal problem. Any other fault and they would remain mostly intact.
    Strange thing is that they blow up only on second try, I would have expected them to blow up right away. Maybe the first surge damaged them and the second one was just too much.

    Here is the ABB's cap reforming guide:
    https://library.e.abb.com/public/371...ructions_E.pdf

    I think that the 1 year reforming interval is overly cautious but if the drive has been sitting unused for 3 or 5 years I would definitely do the reforming.
    I just bought "new" unused ABB vfd from germany, manufactured in 2008 so that is going to get the treatment also.

  5. #5
    Join Date
    Jan 2009
    Location
    Nordland, WA
    Posts
    819

    Default

    I've never seen information on re-forming electrolytic capacitor on a product. I only know about it 'cause 50 years ago I resurrected old radios from the '20s and '30s. In those units when the cap(s) went they took the power transformer with them!!

    Wow.

    Pete
    1973 SB 10K .
    BenchMaster mill.

  6. #6
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    2,056

    Default

    Quote Originally Posted by 10KPete View Post
    I've never seen information on re-forming electrolytic capacitor on a product. I only know about it 'cause 50 years ago I resurrected old radios from the '20s and '30s. In those units when the cap(s) went they took the power transformer with them!!

    Wow.

    Pete
    Local steel mill takes all the spare VFD's out of warehouse once in a year just for re-forming. And they had more than handful of them.

  7. #7
    Join Date
    May 2009
    Location
    Canada
    Posts
    3,245

    Default

    Sorry to read about that misfortune, but posting will be a service to others.

    Quote Originally Posted by ironmonger View Post
    I don't remember seeing it referenced here on this forum, so let this post be a warning to any purchasers of older NOS or used equipment. If I missed said reference, my bad...
    Although in reference to inverter-based welders, the topic of reforming capacitors that had been in long term storage was trending here last week:


    With regard to placement of the reforming comment in your manual. Bear in mind that the manual was written for an audience about to employ the VFD shortly after it had been manufactured. (Unless things have changed, there is little said in an automobile manual about the need to replace tires, belts, fuel lines and other "rubber" articles before putting a car that has been sitting unsold in a backlot for ten yrs into service.)
    "There's a place for us,
    A special place for us.
    Perspiration and chaos and sulfurous air
    Wait for us
    Somewhere."

    (Apologies to Stephen Sondheim who wrote the lyrics and Leonard Bernstein who wrote the music to Somewhere from Westside Story.)

  8. #8
    Join Date
    Sep 2008
    Posts
    502

    Default

    Most all cover themselves with something like this in the first few pages of the manual:

    From a random ABB manual

    Study these installation instructions carefully before proceeding.
    Failure to observe the warnings and instructions may cause a malfunction or personal hazard.

    This particular manual says to reform every year it sits unpowered. Which, if you read (STUDY!) the whole thing, you'll find it mentions several times in the manual I found online. But honestly? Who reads a 326 page manual cover to cover?

  9. #9
    Join Date
    Oct 2005
    Location
    British Columbia
    Posts
    5,961

    Default

    Quote Originally Posted by MattiJ View Post
    If the caps blow up they are probably the orginal problem. Any other fault and they would remain mostly intact.
    Strange thing is that they blow up only on second try, I would have expected them to blow up right away. Maybe the first surge damaged them and the second one was just too much.

    Here is the ABB's cap reforming guide:
    https://library.e.abb.com/public/371...ructions_E.pdf

    I think that the 1 year reforming interval is overly cautious but if the drive has been sitting unused for 3 or 5 years I would definitely do the reforming.
    I just bought "new" unused ABB vfd from germany, manufactured in 2008 so that is going to get the treatment also.
    Thanks for the link. I hadn't notice the OP's reference to the year 2005 as being the year it was produced so I can easily say why I was spared. For some reason I read a different year.
    I don't think mine has ever been out of service for more than 3 months since I installed it in 2003.
    I'm not surprised now, only that the caps lasted until the second power on event.

    A good heads-up never the less!
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories

  10. #10
    Join Date
    Jul 2009
    Location
    Waukesha, WI
    Posts
    1,311

    Default

    Quote Originally Posted by MattiJ View Post
    If the caps blow up they are probably the orginal problem. Any other fault and they would remain mostly intact.
    Strange thing is that they blow up only on second try, I would have expected them to blow up right away. Maybe the first surge damaged them and the second one was just too much.

    Here is the ABB's cap reforming guide:
    https://library.e.abb.com/public/371...ructions_E.pdf

    I think that the 1 year reforming interval is overly cautious but if the drive has been sitting unused for 3 or 5 years I would definitely do the reforming.
    I just bought "new" unused ABB vfd from germany, manufactured in 2008 so that is going to get the treatment also.
    Matt, Thanks for including the link, I should have stuck it in the first post.

    The failure on the second power up struck me as strange as well... all I can say is what I told the minister in a church I was installing plumbing in years ago when He asked why something was as it was:

    "I don't do 'why' questions, I only handle the 'what' questions. The why questions are your busniess."

    It will be enough to just be aware of the problem. I will try to post a pic of the carnage later if the carcase is still around.

    Mike Nash nailed it with "But honestly? Who reads a 326 page manual cover to cover?"

    After 60 years of punishing electrons you never get used to the smell of component death :>(
    paul
    ARS W9PCS

    Esto Vigilans

    Remember, just because you can doesn't mean you should...
    but you may have to

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •