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Determining correct wiring for an old washing machine motor

  1. Sep 22, 2014 #1
    I have an old washing machine that finally bit the dust, so I've decided to attempt several projects with its remains. I want to try to make a mechanical chicken plucker using the tub and motor. I've disassembled and salvaged all the useful parts and scrap metal, but when it got down to trying to make the motor spin, I quickly got stuck. I'm hoping someone can point me in the right direction.

    Here are the specs:
    Washing machine model: Whirlpool LA7800XP
    Motor: c68pxefd-3454

    Here are some photos of the motor and wiring:
    motor_nameplate.jpg


    motor_wiring.jpg

    I would greatly appreciate any assistance/advice.
     
  2. jcsd
  3. Sep 23, 2014 #2

    Baluncore

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  4. Sep 23, 2014 #3
    Hi, Baluncore ... thanks for the response. Yes, I had come across that thread earlier in my research on the net. I followed the suggestions as closely as I could, but my situation's a bit different. I don't have a block on the outside as pictured in the thread, just loose wires. Also, my colors are different. Here's what I've accomplished so far via trial and error:

    motor_test_configuration.jpg

    With this configuration, I have power coming from my test lead plugged into the power strip, directly into the capacitor. Then, from capacitor to motor via the red wire. White is connected to neutral on my test lead, and ground goes to the motor housing. Now, when I connect the green wire running from inside the motor to neutral, the motor spins. However, it spins very slowly (maybe 100 rpm or so), and after a few seconds slows down even more. Connecting the purple wire to neutral at the same time as the green wire is connected to neutral makes no difference. Connecting the purple wire to neutral without connecting the green wire to neutral produces a hum, but no motion.

    Any suggestions what to try next to get this to spin at full speed?
     
  5. Sep 23, 2014 #4

    Baluncore

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    As a single phase induction motor it will have at least two windings. They may share a common wire to neutral or each have it's own neutral connection. One of those windings will be connected to active directly, the other winding will be connected to active through the capacitor which provides the necessary phase shift to decide direction.

    The direction of rotation is determined by which winding has the series capacitor to active. If the motor has separate windings then reversing the two connections to either winding will reverse the motor.

    Measure the resistance of the windings using the low ohms range on a multimeter to identify how many windings there are and how they are connected.
     
  6. Sep 23, 2014 #5
    Ok, I measured the resistance of all combinations of the four wires. Here are the results:

    W R G V
    W 0 8.8 1.9 3.0
    R 8.9 0 10.5 11.6
    G 1.9 10.3 0 3.9
    V 3.0 11.5 3.8 0


    Can you help me interpret the meaning of these results?
     
  7. Sep 23, 2014 #6
    Additional advice: Be sure the chickens are dead before you run them through an electric chicken plucker. They tend to strenuously object if they're still alive. (Voice of experience here)
     
  8. Sep 23, 2014 #7

    Baluncore

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    I guess you did not measure the G-G, V-V, R-R and W-W values. It would tell us the resistance of the multimeter leads. I guess that would be about 0.65 ohm.

    Looks like three connected windings. V to G, then G to W and W to R.

    My guess would be;
    W is common neutral.
    R is connected to active.
    V or G is connected through the capacitor to active.
     
  9. Sep 23, 2014 #8

    jim hardy

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    from 2012 thread:
    https://www.physicsforums.com/threa...-3-wires-into-motor-help.620673/#post-3995969

    ?image=http%3A%2F%2Fi232.photobucket.com%2Falbums%2Fee289%2Foldjimh%2FWashingMachineMotorWiring2.jpg
    Note it always starts in high speed.
    Centrifugal switch opens the start winding and if low speed is selected, swaps over to it.
    Yellow to white-black, and start cap? to blue runs one way, swap to reverse.
    Are you sure yours has no centrifugal switch?


    good luck !
     
    Last edited: Sep 23, 2014
  10. Sep 24, 2014 #9
    The white wire is usually the common and the green wire is almost always the ground wire. There should have been a wiring schematic somewhere within the machine. Sometimes it is on a piece of paper inside of the control panel, others have it pasted on the inside of the back panel.
     
  11. Sep 24, 2014 #10

    jim hardy

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    First thing is to check that none of the wires read continuity to motor frame. Unless it's obviously bolted there (Green?)
    If the windings are grounded the motor has failed insulation. And this sounds like a symptom of that,
    Or it could be just from trying to run at two speeds simultaneously.. Does it have that "Burnt Varnish"smell ?

    hmmm my guess: (Thanks Balun ! )

    R W = ~9 ohms start winding
    G W = ~ 2 ohms run fast
    V W = ~3 ohms run slow

    Voltage across any one winding should make it hum, but don't leave it stalled that way more than a couple seconds.
    Give it a spin by hand either way and it should take off that direction.

    That should work for all three windings.

    Good luck ! Washing machine motors are real handy for home projects.
    But the new ones are 3 phase computer driven marvels of modernity with "Space Vector Field Oriented Control" (see http://www.ti.com/lit/an/sprabq0/sprabq0.pdf),
    so get yourself a lifetime supply of the old type while you can. I like to keep a half dozen on hand myself. They're about two to five bucks at metal recycle yards, yours is $116 new at Sears..


    old jim
     
  12. Sep 24, 2014 #11

    jim hardy

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    Also be aware the start winding will work with only one of the speeds, probably high.

    have fun.
     
  13. Sep 24, 2014 #12

    jim hardy

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    Aha ! Finally got my unruly old brain to focus...

    If we're right on our wiring guesses
    From your post # 3:
    That energizes start winding through capacitor. With only that connection it should run but weakly. Try giving it a spin.
    That shorts out the run fast winding. It might turn a little, but something should be getting hot.
    That shorts the slow run winding too.
    That shorts just the run slow winding. Hmm.... one winding is two pole the other is four pole. I don't know what the motor would do.

    Try energizing a run winding and give the shaft a spin. Use an outlet strip with an overload breaker, just in case. If you can find a GFCI outlet nearby (kitchen?) i'd use that one.

    old jim
     
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