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  1. #1
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    Default Trouble getting old 3 Phase motor to run

    Hi,

    I am restoring an old drill press which has an inbuilt 3 phase motor.
    There are only 3 leads which makes me believe it's a star connection.
    The resistance between each of the wires is 17.4 ohms.

    For a test, I connected it to a VFD, but it only hums and makes a sort of grinding noise, but does not turn.
    I've swapped the cables around multiple times but the problem persists.

    Anyone have an Idea what could be causing the problem?
    Does there need to be some fuse or breaker?

  2. #2
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    What frequency have you got the VFD set to?

  3. #3
    BobL is online now Member: Blue and white apron brigade
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    I agree the frequency may just be too low

    Is the belt connected? if so remove the belt and try again.
    The belt alone could be enough to prevent a is 415V motor starting under 240V 3P.

    BTW 3 wires means it could still be a delta motor.

  4. #4
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    Default

    When I set up a new Chinese VFD on my surface grinder I did not check the Maximum Frequency setting because I was in a hurry to see it go for the first time, the motor just sat there making funny noises until I realized that the drive was set to 400Hz, after resetting to around 60Hz it started and ran perfectly.

  5. #5
    BobL is online now Member: Blue and white apron brigade
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    When connected to a 50Hz motor a Huanyang VFD with a 10s acc time and a 400Hz max will start the motor but switch it off at about 200Hz and report an error.

  6. #6
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    The motor stator had a stamp 40-60 Hz 415v.
    How can I check the frequency which my VFD is running off (currently turning the little pot gives values from approximately 0-60)?
    A different motor will run just fine from the same VFD.
    This drill press is geared, where the entire motor is built into the casting and can be removed.

  7. #7
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    Default

    Hi Mlo18,

    I think that you need to carefully, physically check the motor windings for any damage ! Better yet take it to a motor re-winder and let them cast an eye over it.
    Best Regards:
    Baron J.

  8. #8
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    Default

    Is your motor two speed? How many horsepower? What size drive?

  9. #9
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    Default

    This is the VFD i currently have from ebay: 1,5 KW 3 Phase VFD 220V
    I am not aware of what the HP of the motor is. I will check if the manufacturer of the drill press put the information somewhere.
    I was able to completely remove the stator, I did not see any damage, it looked very good.

    Bear with me, I am still learning.

  10. #10
    BobL is online now Member: Blue and white apron brigade
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    Are you connecting the VFD direct to the motor.
    If you have any sort of switch like contactor in the way this is A) not good for the VFD and B) will not work

  11. #11
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    Quote Originally Posted by BobL View Post
    Are you connecting the VFD direct to the motor.
    If you have any sort of switch like contactor in the way this is A) not good for the VFD and B) will not work
    The VFD is connected directly to the motor.

  12. #12
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by ml018 View Post
    The motor stator had a stamp 40-60 Hz 415v.
    How can I check the frequency which my VFD is running off (currently turning the little pot gives values from approximately 0-60)?
    A different motor will run just fine from the same VFD.
    This drill press is geared, where the entire motor is built into the casting and can be removed.
    Can you turn the gears/motor by hand - it's not locked at the spindle or elsewhere in the gear train by chance?

  13. #13
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    I suspect you have a 415 volt motor in its current setup, It maybe possible to change but expect some work. The load from the gear train might be enough to stop it when you are feeding it 220v 3phase.

  14. #14
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    The motor spins freely even with the gear setup. I have removed all the gears, the motor makes vibrating noises and is hard to turn by hand when the VFD is switched on.
    On one side the motor is easier to turn, then had a sudden jump before stopping again (wrong phases connected?).

  15. #15
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by ml018 View Post
    The motor spins freely even with the gear setup. I have removed all the gears, the motor makes vibrating noises and is hard to turn by hand when the VFD is switched on.
    On one side the motor is easier to turn, then had a sudden jump before stopping again (wrong phases connected?).
    Not phases so much but coils themselves maybe connected incorrectly.

    Has the motor ever run correctly to your knowledge?
    Is there evidence that someone has messed about with the wiring inside the motor end cap - can you open the endcap up and take a photo?

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