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OT Reversing 120 V capaciitor start electric motor

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  • OT Reversing 120 V capaciitor start electric motor

    I have an older chinese made 120 VAC capacitor start motor, 1/2 h.p., 1720 r.p.m., that I'd like to reverse the direction on. I disconnected the start capacitor and can reverse direction by hand when powered up. The schematic shows that I can change this to 220 volt, but no indication on reversing direction.

    Can anyone here tell me which wires I can switch to reverse direction with the capacitor reconnected? Two black wires (one may be gray) are currently paired, as well as a red and yellow. You can see the green capacitor wire hanging out the end: I removed the centrifugal switch for my testing. The capacitor is clearly marked start capacitor.

    I cannot swap ends which would probably do what I want because they made the end collars different sizes.

    Thanks in advance for any suggestions.


    DanL

    Salem, Oregon

  • #2
    There appears to be 4 wires coming from the motor. 1-2 and 3-4 would be from the run windings. Chinese might use ABCD. The 2 wires for the start winding need 120v only so would likely be internally connected one side to 2 or 3 the other side connected to 1 or 4. To reverse you need to move the start winding wire from ether 1 or 4. If it is connected to 1 move to 4. If it is connected to 4 move to 1. Leave the other end of the start winding connected to 2 or 3. I am guessing that the side of the start winding you want is at one end of the series circuit that is the start switch and capacitor. One end being connected to ether 1 or 4 the other end is the start winding.

    Bob

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    • #3
      Thanks, Bob.... I'll try that.

      Dan
      Salem, Oregon

      Comment


      • #4
        Bob, I could still use a little help. There are 2 white insulated wires that lead to the starting winding. In the 120 volt configuration, red and yellow are tied together as well as the black and grey wires, and those pairs see the source.

        The white wire leading to the capacitor has zero resistance to the red and grey wires, while the black and yellow wires show open.
        The white wire leading from the centrifugal switch (normally open) side has zero resistance to the black and yellow wires, and open to the red and grey wires. Obviously, I needed to separate the sourcing pairs to determine those values.

        Any suggestions? This thing is not worth having an electrical shop rewind coils just to reverse direction.

        Thanks,

        Dan
        Salem, Oregon

        Comment


        • #5
          Dan,
          The standard when I wound motors 1961. 1 - 2 are numbers for one run winding. 3 – 4 are numbers for the other run winding. 5 – 8 are numbers for start winding.
          The diagram for dual voltage is a standard. http://www.electricmotorwarehouse.co...n_diagrams.htm

          Your motor is connected for 120v
          Your diagram should tell you what numbers or colors hook together for 120v. And what numbers or colors hook together for 240v.
          The start winding in your motor 120v only and appears to be hooked internally. 5 – 8 are likely tied to 2 – 4.
          Diagram above for low voltage shows 1 – 3 as L1 and 2 – 4 for L2. The 2 white wires you have one goes to one side of the start winding. The other likely is internally hooked to 2.

          You need to pull the end bell and find both start winding ends. One should be connected to a white wire going to the centrifugal switch capacitor mark it 5. On the other side of the centrifugal switch the white wire can be cut and insulated or traced back to the run winding and removed. This side of the centrifugal switch needs a new wire long enough to get to the connection box and marked 5. The other is likely just the coil wire going to the run winding cut it free from the run winding and connect a insulated wire long enough to get to the connection box make it 8.

          Now you should have 6 wires in the connection box and following the diagram above should be able make it run for ether voltage and forward or reverse.

          If I lived closer it would be faster to just show you.

          Bob

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          • #6
            I get the general drift of all that you are saying, but the internal connections to the start coil is what is hanging me up. Take a look at this photo, with the end casing off the motor. 1 and 3 must be the red and yellow wires, with 2 and 4 the grey and black wires. The photo shows the two original white colored insulation start coil wires. I ran one of the white wires out to the terminal and twisted it to the yellow/red pair.They both run to copper coil wiring, but I think one (or both) of them must connect to L1 and/or L2. It is that connection point easier to find in motors made in the U.S.A? Obviously I cannot leave the old internal start winding connections to L1 and L2 intact and make this work.

            Before I begin cutting back the waxy string that serves as binding for the coils, can you tell me what I'm looking for in a connection point? Or points? I really do appreciate your help on this.

            Dan
            Salem, Oregon

            Comment


            • #7
              Dan,

              The start windings are the ones with a finer wire. It looks like the short white wire just above the armature is connected to one end, if so label it 5. This wire will go to the capacitor, from the capacitor to the start switch, from the start switch to the connection box. Label it 5 in the box. This is the series circuit from start coil through capacitor and start switch.
              The other end of the start coils looks like it is in one of the bundles on the right side. Grey red yellow black. You need to locate it cut it free and connect it to a white wire label it 8 and bring into the connection box. This will give you the 6 wires needed in the box. If I am wrong about 5 – 8 all that will happen is the motor will run the opposite direction from the diagram. You could change numbers if important. To make sure you have the start winding by itself connect a OHM meter to 8 You should only get a reading to 5 and it likely will be less than 2 OHMs

              The waxed linen string is there to help keep the windings from vibrating the insulation off the windings. Replace as needed with heavy cotton string. Recommend you go to Grainger and get a spray can of RED INSULATING varnish. This is not for painting, use a heavy spray to get into the windings to help stabilize them.

              Bob

              Comment


              • #8
                Bob,

                THANK YOU SOOO MUCH! That did the trick. Once I knew to look for the connections to run wires, and to separate whichever one had two wires coming out of it, and run the smaller diameter wire directly out to the source and also the one from the other white wire (start capacitor and centrifugal switch) , it worked like a champ, and coincidentally, began running in the direction I need it to go.

                Nearest Graingers is in Tigard, so that may not happen, for the insulating varnish. I can do the cotton string, no problem. I'm not sure there's much varnish type insulation on this chinese made motor anyway.

                Could not have done this without your assistance.

                Thanks again.....

                Dan
                Salem, Oregon

                Comment


                • #9
                  Dan,

                  Good to hear you won! The insulating varnish will seal the windings and help stop the smoke from escaping. A couple of web sites to show what you are looking for which sometimes is in a local hardware store. The first one is the old standby. The second should also be OK.

                  http://www.chemical-concepts.com/gly...lectrical.html

                  http://www.mcmaster.com/#electrical-...arnish/=v21j4t

                  Bob

                  Comment


                  • #10
                    I wanted to summarize my efforts on this in case someone else has the need to reverse the direction of their single phase 120 volt motor. My motor was from my 30 year old chinese drill press, on which it rotated counterclockwise. This is a 1/2 h.p., 1720 rpm (I know, weird, huh?), capacitor start motor that I'm re-purposing on my 1904 Seneca Falls "STAR" 9" metal lathe.

                    This is a dual voltage motor, but it was set at 120 volts, which is what I wanted to retain. On one side, yellow and red insulated wires (# 1 & 3) connected at the source, while grey and black wires (#2 & 4) connected on the other side, with a green neutral wire to the motor case.
                    Next, thanks to help from Bob Ford, I was able to isolate the start coil and connections. One end of this coil ran via a white insulated wire to the start capacitor, then to the centrifugal switch. The other end was connected to the black (# 4) wire, underneath a fabric covering, at a soldered joint. The start coil uses smaller diameter wire, which should help locate it in case of doubt, although it is difficult to see in my photo:



                    The white wire in the left side of the above photo was extended to wrap around the armature to the bottom to allow connection to the centrifugal switch. On the other side of the switch, a green wire runs back to the capacitor, and from the other terminal of the capacitor, a new white insulated wire exits the motor interior at the wiring connection point with a source 120 volt pigtail, along with the black and grey wires.

                    At the other end of the start coil, I clipped the thinner diameter start coil wire and re-insulated the black connection to the run coil. The newly clipped wire was then soldered to another white exiting the motor interior and connecting to the black and grey wires. I believe one would always want to stop this motor completely before trying to reverse directions in any case, since you would have the start coil opposing the run coils if you tried reversing direction via a switch with the armature still spinning.



                    Now I rewrapped the original run and start coils with some 1/16" diameter waxy cotton twine, and will cover all disturbed coils and internal connection points with insulating electrical varnish.
                    Salem, Oregon

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                    • #11
                      Question for Bob:- If red insulating varnish is not readily available, would a generous "slather" of epoxy resin work as well? Seems to me that it would gradually penetrate the windings before setting up. you would have to be carefull that the epoxy was not too thin, or it would ooze out and pile up at the bottom of the housing.
                      Duffy, Gatineau, Quebec

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                      • #12
                        As long as the wires can't vibrate, which wears though the enamel insulation.

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                        • #13
                          Duffy,

                          It has been a long time early 60's. Yes we built a form for the stator and outside the coils used a special encapsulating epoxy Red in color. This was for 3 phase motors in wet corrosive area's. You poured it in one end and it ran through the windings and filled the other end. When done all you could see was a ring of red epoxy. If the forms did not hold you had one hell of a mess to clean up. I think you could look this up or just use a high temperature epoxy without any metal in it.

                          Bob

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                          • #14
                            Glyptal Products and motor connections.

                            http://www.glyptal.com/Glyptal_Product_Data_Sheets.htm
                            http://www.usmotors.com/TechDocs/Con...-Diagrams.aspx
                            http://www.glyptal.com/
                            Max.

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