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Thread: VFD Questions

  1. #1
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    Default VFD Questions

    I am attempting to run a 1/2Hp 3ph geared motor from single Ph using a VFD. Using VFD because it is apparently cheaper and simpler regarding speed control, I need on/off forward/reverse and speed control,
    problem is the motor has lost most of it's torque I am told that this is the result of using VFD.
    What is recommended if I dispense with the VFD and just run 3Ph controller.

  2. #2
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    Hi Bob,

    This problem may be that the motor is intended to run on 380/400 volts three phase and your VFD only outputs 230/240 volts. The cure for this is to change the motor winding configuration from star to delta wound. Sometimes you can do the easily in the terminal box other wise its a strip down and hunting out the star point, splitting it to create three separate windings that you can reconnect in delta.

    Check what it says on the rating plate ! Sometimes there are six terminals in the connection box along with three links. But this isn’t always a reliable method of determining whether the configuration can be changed there.

    HTH.
    Best Regards:
    Baron J.

  3. #3
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    You can also get the step up VFDs that will convert 240v 1ph input to 380v 3ph output. A couple of common Chinese brands are Ecogoo or Nflixin
    I've got mine from AliExpress, usually the Ecogoo store (all mine are Ecogoo ones).
    There's a thread around somewhere about my experiences with them - search for "Ecogoo"

    I've got 3 or 4 of them here now, and so far no failures or issues. The only negative with the small ones is that they really need to go in an enclosure as the physical terminal protection on them isn't great.

    Steve

  4. #4
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    ditto what Barron and Steve say...and also is the VFD a vector drive type?.

  5. #5
    BobL is offline Member: Blue and white apron brigade
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    Maybe have a read of this document - I wrote it for the woodies forums but it could prove useful here too.
    I might put it as a sticky in the electrical forum.
    VFDs4Newbies2.pdf

  6. #6
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    I assume its covered in Bob's link but how sure are you that the VSD is setup correctly?
    What VSD do you have?
    "the motor has lost most of it's torque" At 50Hz, starting or something else?

    The default settings on most of the VSD's I have result in "low torque". The default settings on the VSD are not what the manual says they are. I THINK it was base Freq set to 400Hz that was my issue.

  7. #7
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    Thanks for the replies I will need to to some playing around will post to out come.

  8. #8
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    Can you post a picture of the I/D plate on the motor?

  9. #9
    BobL is offline Member: Blue and white apron brigade
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    Apologies if I offended anyone with the title of the document on VFDs I attached.
    Title has been amended.

  10. #10
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    Also, some VSD's can 'boost' the low speed torque of the motor, via a parameter or two.
    That might help some.

  11. #11
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    Hi...are you located in Adelaide?

  12. #12
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    Default

    erick's 2

    Morphett vale

  13. #13
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    Techo 1

    P1010457.jpg

  14. #14
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    Quote Originally Posted by China View Post
    Techo 1

    P1010457.jpg
    I will bet that the motor can be altered under the terminal box cover, look on the inside of the lid there is often a diagram showing how to change the motor configuration from star to delta.

    Also have a read of this thread !

    https://metalworkforums.com/f316/t20...sting-pictures
    Best Regards:
    Baron J.

  15. #15
    BobL is offline Member: Blue and white apron brigade
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    I agree with BJ - the underlined 220-240D means it can be converted to delta
    Chinamotor.jpg

    However, unless powered by a vector drive VFD its output power is still only going to be proportional to frequency up to 50Hz.
    ie
    At 25Hz its going to be able to deliver 1/2 its rated power
    At 12.5Hz . . . . . . . . . . . . . . . . . . . 1/4 . . . . . . . .
    etc

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