Can anyone decode this ac motor's wire colors?

Discussion in 'General Electronics Chat' started by benrst, Apr 18, 2011.

  1. benrst

    Thread Starter New Member

    Apr 18, 2011
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    I have a salvaged 120vac motor that came from some kind of ventilation unit, maybe a range hood. It appears to be multi-speed. The motor is about 3"x3" The Chinese mfr. does not get any hits when I search. The spec plate does not say much: Thermally protected, Class A, A032WG, 16/U, 3, D. There is a 2.5mfd capacitor: red wire connected to yel wire going to motor and black wire connected to black wire going to motor. The remaining color motor wires are blue, red, white and gray. Resistances are as follows:

    red/blue: 114 ohms
    red/white: 69 ohms
    blue/white: 45 ohms

    Can anyone decipher how to wire the AC and for what speeds? Thanks.
     
  2. benrst

    Thread Starter New Member

    Apr 18, 2011
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    Thanks for reply. Sorry about that. MS Word file w/photos attached.
     
  3. benrst

    Thread Starter New Member

    Apr 18, 2011
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    I tested again, with the same results as my original post.

    I rounded off all readings to the nearest whole number:

    red/blue: 114 ohms
    red/white: 69 ohms
    blue/white: 45 ohms

    No other combinations gives a meaningful resistance, unless you find 100s of megohms to be meaningful: white/gray, blue/gray and red/gray all show .8 on the 200 megohm scale.

    However, there appears to be a capacitance reading for these same colors:

    red/gray: 6 mfd
    blue/gray: 4 mfd
    white/gray: 5 mfd

    Out of curiosity, I retested the original combinations for capacitance:

    red/blue: 15 mfd
    red/white: 26 mfd
    blue/white: 41 mfd

    Don't know if any of this helps. Thanks.
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    Here are the motor photos for those of you who don't use Word.

    Although the OP didn't indicate that the motor was malfunctioning (and maybe it's not), if it is, a potential problem area is the thermal protector. If it has opened, then the resistance readings would be misleading.
     
    Last edited: Apr 24, 2011
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
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    Can you measure you measure any resistance between any of these wires to any of the other two?

    red/blue: 114 ohms
    red/white: 69 ohms
    blue/white: 45 ohms
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    That is an induction motor
     
  7. benrst

    Thread Starter New Member

    Apr 18, 2011
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    I think I have solved the mystery.

    No other wire combinations suggested above gives a meaninguful reading.

    However, it occurred to me that I could simply try testing the motor, but rather than connect the full 120vac, for safety reasons maybe I could connect a low voltage source to see if the motor shaft will turn.

    I assumed that the wires with resistance would be the ones to try. I tried a conventional transformer with a 30v out winding and the motor turned using the blue/red, blue/white and red/white combinations.

    Now in order to see if the motor is of any use, I need to determine which combination produces low, med. high speed, if that is the difference and whether the torque is enough to be worth the trouble or keeping it at all.

    Thanks for your help.
     
  8. Ali Baba

    New Member

    Apr 24, 2011
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    this is a single phase induction motor
    the red-white 69 ohms is the start winding
    the blue-white 45 ohms is the run winding
    from red to blue you get 69+45=114 ohms the total resistance of start+run windings
    the 2.5 mfd cap is to be connected to the start winding at red end and to line phase
    the blue wire from the run winding also connects to phase line
    the white wire connects to mains neutral

    http://www.electrical-contractor.ne...ics/148744/Schematics_For_1_Split_Phase_M.htm

    this site may be useful as it has the pictures
     
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