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electric motor problem?

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  • MaxHeadRoom
    replied
    Maybe take a continuity reading of the motor terminals, if you have two rows of three.
    with 1-3 across the top and 4-6 the lower row, left to right.
    Indicate the 3 winding terminations would help verify whether it is 'standard' termination.
    Max.

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  • Black Forest
    replied
    I will try to get some decent pictures of the switch. I am trying to test the switch to make sure everything is functioning as it should.

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  • J Tiers
    replied
    probably one can try the "left shift" and if that is not correct, try the "right shift". One will be correct for delta with correct rotation and phase order relative to the "wye" or star (Stern) connection.

    Takes little time, and with a VFD, at least, won't cause damage or overstraining of anything (current limits are nice)
    Last edited by J Tiers; 05-27-2010, 11:21 PM.

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  • MaxHeadRoom
    replied
    My method is a lot simpler and quicker, no need to open up the motor.
    Its crude, but it has worked for me in the past.
    Max.

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  • J Tiers
    replied
    If you take apart, you can do with a battery and cheap compass (the north-finding type). I have not done it for a while, so I will refrain from describing it, but the idea is to verify that you have alternating N and S poles around the stator. Lots of work, probably not worth it.

    Yes, two sets of wires of same colors. Each set goes to one side of the connecting block.

    you have said they are black,red,white on one side. Each color should be a coil (black to black, for instance), and each group should all be "+" ends or "-" ends.

    So on the other three terminals they should either be red,white,black, or white, black, red. That is, each color is moved one space to the side, and the one that is off the end comes around back to the beginning.

    if you draw a little picture you will see that in that way the connecting of all one side together will connect "wye", and connecting "across" from one set to the other will put them in series around a "delta" connection.

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  • MaxHeadRoom
    replied
    Did you identify them with a continuity test? Is there in fact three sets of coil with no continuity between the three sets?
    This is what I would expect to see for star-delta operation.
    If you do have three coils, there is a way I have used in the past to phase them correctly using a meter and a Gel-cell or automotive battery, I can post if you need it.
    max.

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  • Black Forest
    replied
    two sets of wires coming off the windings.

    There are two sets of wires coming off the coils. RED, White, Black. On each side. So six wires in two groups. They are off set but I couldn't tell you how they are off set.

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  • J Tiers
    replied
    Even if it lost one phase wire, the already-turning motor (started "wye") should continue to turn...... millions of "static converters" prove that.

    If the wires got scrambled at the motor connecting block, then anything might happen.

    There are basically only two wire configurations on the block that need to be tried..... offset 'right" by one position, and offset 'left" by one, for the "delta" connection.

    Most motors seem to bring the wires out in two separate bundles, one for the "+" end of the coils and one for the other end. That, if true of this motor, makes it easy.

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  • Black_Moons
    replied
    Id wonder if its not the switch thats failing to connect all 3 coils properly in the other mode. I mean if the motor works in one mode but not the other, and hasent been altered recently, Id check mechanical wearing components first (Aka, switchs, brushs, etc)

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  • Black Forest
    replied
    The name plate on the motor is gone. So I don't know actually how many HP the motor has. But it is very heavy! I am completely guessing, but compared to some other motors that I have it must be in the 5 HP range.

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  • MaxHeadRoom
    replied
    You did not mention what size the motor was and the load, but if it comes up into run fast enough in delta, I would not bother with the star-delta start.
    It may have been an original overkill or the saw blade load was such that star delta was originally needed.
    Max.

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  • The Artful Bodger
    replied
    BF, I imagine in the wye configuration one end of each coil is connected to a supply leg and the other three ends are all connected together. To change that to a delta the ends that are connected together would be seperated and each connected to one of the other legs.

    If it is a dual voltage motor things could be more complicated and more options for getting it wrong.

    John

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  • Black Forest
    replied
    I figured out which wires should be paired at the motor. I paired them and wired the motor to power without the switch, just a plug. Motor runs good. So I will just get a different switch with only off/on and use the motor always on 360volts three phase.

    Later I will try to figure out how the Delta switch works. Thank you for your help.

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  • The Artful Bodger
    replied
    Black Forest, you can test to find the end pairs of each coil by using a meter, a very simple one is good enough, set on the resistance scale. You could also use a low voltage light globe or a buzzer etc and a battery.

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  • Black Forest
    replied
    Would someone be so kind as to tell me how I can test the coil wires in order to pair them correctly?

    Please explain it as if you are dealing with an idiot( because I am when it comes to electricity!)

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