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  1. #16
    Join Date
    May 2020
    Location
    ACT
    Posts
    27

    Default

    I'm also running a VFD on my 260 and do get some odd balance issues when running past about 60Hz and more than about 450 RPM. It will vary depending on how loaded the motor is, I have isolated the issue to the motor. I get around it by using the VFD to tune the vibration out; usually by moving about 50 RPM down or up it will go away. I suspect if I were to replace the 3 phase motor with a new, high quality unit the problem would not disappear entirely as these motors (squirrel cage construction) do have a propensity for vibration at certain frequencies. Quite a few PHD thesies on the topic have been written. Having just said that, it really doesn't cause me any issue because I'm able to avoid the particular harmonics through a very easy turn of the speed dial!

    Craig.

  2. #17
    Join Date
    Sep 2006
    Location
    Wandong
    Age
    60
    Posts
    31

    Default

    An interesting topic!
    As part of my Hercus reno, I also swapped the the old clunky 240V motor to a 3 phase driven from a VSD... that gave me my variable speeds and I could overdrive to get a faster spindle speed.
    As a result, I found vibration at certain speeds where I didn't have any previously - mainly at the new top speed (From memory, about 1K RPM), but at various RPM's right through the range.
    I didn't put it down simply to the addition of the VSD, but because I suddenly had infinite speeds that I could run at. At some of the new speeds, the harmonics became apparent caused by imbalance on the spindle drive pulley. (Found by running each part of the drive system one at a time to locate the problem component)
    The only way I could 'fix' the problem was to do a static balance on my pulley - a long and slow process that 95% fixed the problem across all the speed range. (The pulley was the culprit in the end)
    There's a link to my you-tube video in another thread that might give some clues as to what your problem might be... or at least, give you a few ideas and clues that could help

    Hope it helps

    Merry Christmas to all!

  3. #18
    Join Date
    May 2020
    Location
    ACT
    Posts
    27

    Default

    Quote Originally Posted by Malibu View Post
    An interesting topic!
    As part of my Hercus reno, I also swapped the the old clunky 240V motor to a 3 phase driven from a VSD... that gave me my variable speeds and I could overdrive to get a faster spindle speed.
    As a result, I found vibration at certain speeds where I didn't have any previously - mainly at the new top speed (From memory, about 1K RPM), but at various RPM's right through the range.
    I didn't put it down simply to the addition of the VSD, but because I suddenly had infinite speeds that I could run at. At some of the new speeds, the harmonics became apparent caused by imbalance on the spindle drive pulley. (Found by running each part of the drive system one at a time to locate the problem component)
    The only way I could 'fix' the problem was to do a static balance on my pulley - a long and slow process that 95% fixed the problem across all the speed range. (The pulley was the culprit in the end)
    There's a link to my you-tube video in another thread that might give some clues as to what your problem might be... or at least, give you a few ideas and clues that could help

    Hope it helps

    Merry Christmas to all!

    Hmmm, you have me thinking I should check if some of my vibration is being introduce by the motor pulley?

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