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3 Phase Static converter sometimes works

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  • 3 Phase Static converter sometimes works

    I have a static converter that I have used with my Bridgeport mill for years. I just bought a used Logan lathe with a three phase motor and to test it, hooked it up to my static converter. The lathe motor turns slower than normal, vibrates and gets hot quick. I have a nice rotary power supply on the way, but does it sound like my lathe motor has a problem. They are both 1 HP. Or are there different 3 phase motors?

  • #2
    Is the lathe hooked up for high voltage?


    • #3
      What size static converter and is it regular duty are heavy duty . will make a lot of difference . The lathe is harder to start than the mill. Make sure lathe is wired for 220 and not 440
      Every Mans Work Is A Portrait of Him Self


      • #4
        More info

        The motor is wired for 240v not 440, and this is with the belt off the lathe so there is no load at all. That said, it's a cheapo static converter with nothing more than a large capacitor. But I would have thought it should at least run.


        • #5
          If the motor shaft turns free, It sounds as if it is single phasing. Check if you are able with an ohm meter the resistance between the motor leads. Have you checked to see that the motor leads are on the correct motor leads for the voltage and a set of wires has not been connected wrong?


          • #6
            Ohm Meter

            The motor turns free and I checked the wiring diagram and all the wires are connected properly

            4-5-6 tied together

            9-3, 8-2 and 7-1 are my power in.

            I tested the resistance between the three power leads and they are all the same at 5.0. (At least my meter reads 5.0 with the scale set to 200).


            • #7
              Maybe your converter is just too light but it should still turn the motor. The last one I built I had an idler motor twice the size of the one I was trying to run. It worked well but my lathe always seemed to strain it some.