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Reversible AC motor wiring question.

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  • Reversible AC motor wiring question.

    Some time ago I bought one of those stupid little 3-in-1 machines off a FeeBay vendor. The machine was destroyed in shipping. After settling with the vendor I got to keep the busted bits.

    I salvaged the motor from the thing as it is small and reversible.

    While I'm sure this is no gem it might be good for a micro lathe I have sitting here.

    The label has been painted over and efforts to reveal the info on the label has been fruitless.

    The motor is 110V and has 4 wires coming out of the case. The schematic for the same machine from a different vendor shows the wires as such:

    First coil:

    Black. This has a capacitor inline and goes to the hot AC lead

    Brown. Goes to the neutral AC lead.

    Second coil:

    Green w/yellow stripe.

    Green.

    The coil with the green wires is switched between the brown and black wires to change direction.

    The black and brown leads are not switched except at the main power input.

    Anyhow, my question...

    Does that sound correct? I know pretty close to zero about how AC motors work. An explanation, or link to a web site with details would be appreciated.

    Thanks in advance.
    Mike N

    Occasional maker of swarf.

  • #2
    Sounds like it should work, why not just try it and see? That's what I did with my recent lathe motor

    If it hums but don't spin turn it off quick
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

    Comment


    • #3
      The wiring coloring sure is strange but as with most induction/cap start motors there's usually 2 circuits. One is for the run winding which I assume would be the wire set without the capacitor and the other is the start winding which determines which direction the motor will start. By reversing the start winding wires the motor can be run in the opposite direction.
      gbritnell

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      • #4
        Here is how my single-phase lathe motor is wired for reversing:

        Peter - novice home machinist, modern motorcycle enthusiast.

        Denford Viceroy 280 Synchro (11 x 24)
        Herbert 0V adapted to R8 by 'Sir John'.
        Monarch 10EE 1942

        Comment


        • #5
          Originally posted by gbritnell
          The wiring coloring sure is strange but as with most induction/cap start motors there's usually 2 circuits. One is for the run winding which I assume would be the wire set without the capacitor and the other is the start winding which determines which direction the motor will start. By reversing the start winding wires the motor can be run in the opposite direction.
          gbritnell
          George,

          After close inspection of the motor and reversing switch, neither of which bear the same wiring colors, I see the schematic offered in the manual is wrong.

          It shows the circuit with the cap as non-switched. The reality is the other circuit is the non-switched circuit.

          I'm going to rig up some wiring later this morning. I've been up all night nursing a pretty bad bug and am about out of energy.

          Peter and George, thanks for the help. now I have a better understanding of this.

          I'll report my findings later. If I don't burn the house down.
          Mike N

          Occasional maker of swarf.

          Comment


          • #6
            http://www.metalwebnews.com/howto/el.../elec-mtr.html

            Comment


            • #7
              Originally posted by Twmaster
              George,

              After close inspection of the motor and reversing switch, neither of which bear the same wiring colors, I see the schematic offered in the manual is wrong.

              It shows the circuit with the cap as non-switched. The reality is the other circuit is the non-switched circuit.

              I'm going to rig up some wiring later this morning. I've been up all night nursing a pretty bad bug and am about out of energy.

              Peter and George, thanks for the help. now I have a better understanding of this.

              I'll report my findings later. If I don't burn the house down.
              It does not matter whether you reverse the start winding or the run winding. Either will reverse the motor.

              Your motor may be a "PSC" motor which means both windings are always powered. If so, there is no start switch and the capacitor is a different type and value. It makes no difference in how you reverse it.
              Don Young

              Comment


              • #8
                Originally posted by Don Young
                It does not matter whether you reverse the start winding or the run winding. Either will reverse the motor.

                Your motor may be a "PSC" motor which means both windings are always powered. If so, there is no start switch and the capacitor is a different type and value. It makes no difference in how you reverse it.
                Actually, at least some PSC can be reversed by swapping one line connection from one side of the cap to the other...... which swaps the main and "phase" windings.

                The type this works on have two identical windings, and they are connected together internally at the opposite end....
                1601

                Keep eye on ball.
                Hashim Khan

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                • #9
                  One more question... How do I determine which winding gets the capacitor?

                  I'm somewhat apprehensive about burning something up, or perhaps down...
                  Mike N

                  Occasional maker of swarf.

                  Comment


                  • #10
                    If the motor has a centrifugal switch, the winding that is connected through that switch gets the cap. You can usually see the switch through a vent hole in the rear end plate.
                    Peter - novice home machinist, modern motorcycle enthusiast.

                    Denford Viceroy 280 Synchro (11 x 24)
                    Herbert 0V adapted to R8 by 'Sir John'.
                    Monarch 10EE 1942

                    Comment


                    • #11
                      Originally posted by Peter.
                      Sounds like it should work, why not just try it and see? That's what I did with my recent lathe motor

                      If it hums but don't spin turn it off quick
                      Or just spin the shaft...you'll act as the start winding.

                      I have poked around with lots of unknown motors doing that. Just plug it into a power strip that has a breaker on it. No smoke yet!!

                      Comment


                      • #12
                        Chester,

                        Thank you. That is a great idea and I just happen to have a nice littl power strip with a breaker.

                        Mike N

                        Occasional maker of swarf.

                        Comment

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