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  1. #1
    Join Date
    Jul 2001
    Location
    Good bay
    Posts
    50
    Rep Power
    24

    Rockwell LiquiFlo AC drive



    Have been working on Rockwell LiquiFlo AC drive of 643A with C- Frame. Customer called that the Breaker tripped, when reached site found One of the SCR had burst open, and two were short. All other components checked OK so just ordered the 3 SCR's and fixed on the drive. Powered the drive and it worked well for about 02 hours and tripped indicating "UbS". Checked DC bus voltage and found +ive to -ive was 76V and to midpoint was 156V. Three ceramic resistors R12, R13 and R14 are open.
    And also the display on RMI went blank.

    Before just replacing the resistors what other things I can check.

    Thanks.


    Setrite

    A group of Donkey's Led by a Lion can defeat a group of Lion's led by a Donkey

  2. #2
    Join Date
    May 2007
    Location
    Auckland
    Age
    74
    Posts
    3,362
    Rep Power
    37

    Re: Rockwell LiquiFlo AC drive

    The power card on drive is unservicable, power surges etc., have corrupted everything and sundry.
    Best course of action is replace total unit. Typical Allen Bradley.

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