How to decipher the wiring schematic of a 110/220V single phase motor?
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  1. #1
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    Default How to decipher the wiring schematic of a 110/220V single phase motor?

    I have an older (1950s - 1960s ?) capacitor start, two-voltage single phase motor that I can not figure out the correct wiring. I have the high-low connection diagram but the wire coloring does not match (possibly somewhat faded but unlikely) the diagram and I am nervous about guessing and letting smoke out of the windings.

    Can anyone help me decipher how to connect this to high voltage?

    The wiring all looks OEM and appears unmodified. There should be four colored wires - black, yellow, red and green; and two numbered wires - tagged 1 and 2. The problem lies with the colored wires. None of the colors are clear (these have a cloth braided outer sheath), even inside the housing. If I were to guess at the existing colors, I would say white, yellow, black and red. Three of those match but that leaves a white where there should be a green, and it certainly does not look that faded. (the two numbered wires are clearly tagged with a metal clip.

    None of the wires is shorted to ground. As I color them, the yellow - red and white - black show continuity to each other but to nothing else.

    The four colored wires all go straight to the field winding. Number 2 wire goes to the winding and number 1 goes first through a capacitor then to the winding.

    The motor shows no evidence of damage and I am told it was running before I got it but the connections were undone. See photos of wiring diagram and motor nameplate.

    Thanks for any help.
    Jim
    Attached Thumbnails Attached Thumbnails the_brown_derby_14.jpg   the_brown_derby_13.jpg  

  2. #2
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    It's a standard 115/230 capacitor start/induction run motor.

    Placing the two run windings in parallel ... Black to yellow to 1 and red to green to 2 ... gives 115 volts. Exchange 1 and 2 to reverse the motor.

    Placing the two run windings in series ... yellow to red to 2 gives 230 from black to 1 and to green. Move 1 to green to reverse the motor.

    In this configuration, the motor always starts on 115, but runs on 115 or 230.

    Black is the start of one run winding, red is its end.

    Yellow is the start of the other run winding, green is its end.

    Given the two leads which are indicated with numbers, and only one colored lead of each of the remaining two windings, any voltage and direction combination can be determined by continuity tests alone.

    The patent on the nameplate, 2,184,411 refers to a new type of centrifugal starting switch which, as usual, is normally closed, but opens when the motor reaches 80 percent, or so, of synchronous speed.

  3. #3
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    Default It works....

    Thank you, Peter. I have much to learn about motors and you helped advance my knowledge.

    Simply knowing that this is has two run windings and they are wired parallel on low voltage and series on high voltage enabled me to figure out what was what by continuity checks. The wire colors are nothing like shown on the provided diagram.

    I was impressed during disassembly how well made the motor is, expecially compared to what one sees new today.

    Thanks again,
    Jim

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    To put this in another format:



    The idea is the dual voltage motor has only a single voltage start winding, they
    take advantage of the center tap on the run winding to cut the voltage in half,
    and connect the start circuit there.

    Jim


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