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  • 3 Phase Power

    I have the opportunity to get a 14” Rockwell radial arm saw with a 3hp 220V 3-phase motor.
    Would a static phase converter work to get the motor running & then run on standard 220V. Or would I need to get a rotary phase converter to provide 3-phase power?

  • #2
    Re: 3 Phase Power

    The cheapest and by far the easiest thing would be to replace the motor with a single phase unit.

    Comment


    • #3
      Re: 3 Phase Power

      the static converter will do a good job of starting the motor,

      the motor will run on single phase once started, but will only produce approx. 2/3 the power of the name plate, so if you do not over load it it will work fine,

      the rotary converter is better as it basically generates the third leg, (the rotary converter needs to be running before the machine motor is started),

      If you have a spare three phase motor and a static converter you can use them as a rotary converter, (the three phase motor needs to be at least as large as the motor wanting to be driven, better if larger, and the static converter matched),
      and there are ways of making a converter with a larger three phase motor and a fractional HP motor to start the three phase motor/converter, plans are on the net)

      on loads that have high starting requirements a rotary converter is necessary, pumps, compressors, and other,
      saw, drill presses and like that do not start under load can use a static converter,

      I have used commercial manufactured, static and rotary converters in my shop for years until I was able to get three phase in the shop,

      you need to watch what wires the control circuits are connected to (starters and any other), on the rotary the third manufactured leg is not as stable as the Power companies, it will fluctuate voltage wise, as load changes,

      the static converter basically used the third phase, winding in the motor as a start winding and when running it kicks out, and runs on single phase,
      Push sticks/blocks Save Fingers
      ~~~~~~~~~~~~~~~~~~~
      "The true measure of a man is how he treats someone who can do him absolutely no good."
      attributed to Samuel Johnson
      ~~~~~~~~~~~~~~~~~~~
      PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

      Comment


      • #4
        Re: 3 Phase Power

        Originally posted by Speedy Petey View Post
        The cheapest and by far the easiest thing would be to replace the motor with a single phase unit.
        I was thinking the same thing! But the yokes pivot brackets are spot welded or riveted to the motor's housing. I did find a replacement 3hp single phase motor at Mikestools, But at $3200 I doubt they sell any.

        Comment


        • #5
          Re: 3 Phase Power

          That's a flippin' joke. You can get a whole UniSaw for that can't you?

          Comment


          • #6
            Re: 3 Phase Power

            Originally posted by BHD View Post
            the static converter will do a good job of starting the motor,

            the motor will run on single phase once started, but will only produce approx. 2/3 the power of the name plate, so if you do not over load it it will work fine
            Thanks for your reply!
            Being the motor is only running on single phase, Will it have a tendency to bog down easily?
            I can get the saw for under $100 & a static converter for around $150!
            If I needed to use a rotary converter that would run me $400 ~ $500 alone!

            Comment


            • #7
              Re: 3 Phase Power

              I ran my milling machine on the static converter for years, and never really noticed it bogging down, and have noticed little difference on three phase,

              the thing is your only using 2/3 of the motor so you only have 2/3 of the power,
              it would act like a saw with a 2 hp motor,

              I would think if you watch what your doing you will be fine,

              Like I said if you want get a larger 3 phase motor, (say a 5 hp and do not hook it up mechanically to any thing (or use it to power a Dust collector),
              and use the static converter to start it, (if used to power some thing derate it at lest by 2/3's) (if a dust collector Idea was used, one would most likely need to make there own collector as the blower would need to rate for a 3 hp motor but you would power it with the 5 hp, as it would produce reduced power)

              and then it will work like a rotary converter,
              that way your saw will have basically 100% of it power capabilities,

              actually the more three phase motors on that circuit the more stable the power would become as ever motor then helps generate the additional third phase, there is a limit, on how many one can add.
              Push sticks/blocks Save Fingers
              ~~~~~~~~~~~~~~~~~~~
              "The true measure of a man is how he treats someone who can do him absolutely no good."
              attributed to Samuel Johnson
              ~~~~~~~~~~~~~~~~~~~
              PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

              Comment


              • #8
                Re: 3 Phase Power

                Originally posted by BHD View Post
                I ran my milling machine on the static converter for years, and never really noticed it bogging down, and have noticed little difference on three phase,
                Thanks again!

                Originally posted by BHD View Post
                the thing is your only using 2/3 of the motor so you only have 2/3 of the power,
                it would act like a saw with a 2 hp motor,
                Yea I don't think that would be a big problem, The thickest thing I would probably cut is a 4”X 6” Landscape timber!

                Comment

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