Single phase dual voltage six wire motor wiring
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  1. #1
    Join Date
    Nov 2005
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    Default Single phase dual voltage six wire motor wiring

    I have a Sebastian lathe with what I originally thought was a three phase motor. After cleaning the wiring up I believe it is a single phase dual voltage motor. I have six leads, three yellow, three black. There are three pairs I was able to identify using an ohmmeter (no labels or tags on the wires). The yellow of one pair is connected to a capacitor. I am assuming I have two run circuits and one starting circuit.

    I am assuming this is single phase. The only other explanation I could come up with is that this is a six wire three phase with a starting cap on one phase to get it to turn over and run on single phase. (simple static converter type setup). I don't believe this is the case but it is a possibility.

    Here are pictures of the drum switch. Please pardon the Romex. I'm trying to clean up after the previous owner's wiring job.

    I have two ideas about how to wire this motor and the switch. One requires seven of the contacts to be used (and five wires between the switch and motor not including L1 and L2(my two hot feeds)) and the other method involves just five contacts and three wires not including L1 and L2. I feel a bit more confident about the first method actually working, but I am wondering if the second method would work just as well. The first method is based on the diagram labeled "dual voltage main winding only":

    The second method comes from diagram 1 on the top left (higher voltage):

    I'm using the following numbering scheme:
    1: First run circuit yellow
    2: First run circuit black
    3: Second run circuit yellow
    4: Second run circuit black
    5: Start circuit yellow
    8: Start circuit black

    Since I will be running this motor at 220v I am assuming I will need to connect the two run circuits in series. This means #2 and #3 will be tied together. The following diagrams should be now be understandable.

    Are both methods correct? Will Method 1 work properly? I would like to use the simplest connection method.

    EDIT: I see my ASCII diagrams don't display properly when posted. I will draw them up and post them as photos in a few minutes.

  2. #2
    Join Date
    Feb 2004
    peekskill, NY
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    I'm still staring at the details here. My first guess
    is that either menthod would work but on one of them
    of course you need to make some non-switched connections
    to the motor leads which are not shown.

    The start ckt as you say goes to the center-tap of the
    run windings (which as you say are in series) and you want
    to basically power the other end of the start ckt off
    either line, respectively, to reverse.

    Another way to look at the task, using a simpler three
    pole, double throw drum switch, which makes the desired
    connections more obvious:

    In that setup the run windings are simply energized from
    L1 and L2, the same in forward or reverse. The run winding
    end is tied to L1 or L2 for forward or reverse.

    Your drum switch has some of the logic built into it
    of course.


  3. #3
    Join Date
    Nov 2005
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    I pulled the plate off of the motor and my initial assumptions might not have been correct. I am starting a new thread in this forum.


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