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electric motors

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  • electric motors

    I recently purchased a 2 hp motor for a table saw from Harbor Freight manufactured in China. I knew this was not a top quality motor but this was a second saw that I only wanted to use occasionally to cut dados. It did not develop anywhere close to the power of other 2hp motors I have so I took it back and got another, same story. How do you judge an electric motor's compatibility other than by the horse power ratings.

  • #2
    You really can't on cheap import motors. The best you can do is look at the motor amps on the nameplate. HP figures for consumer grade motors and shop equipment are little more than frauds.

    In single phase import motors 2 HP and under look for about 10.5 Amps per HP @115 Volts and 5.5 Amps per HP @ 230 Volts. It aint really that simple but for smaller induction motors it's close enough for a guess-timate.

    There are many import motors as good or better than US made motors, Hitachi for example but you pay about the same price as domestic.

    If you look through the surplus outfits on the internet you can frequently find premium grade US made motors for discount prices. Run a Google search "single phase induction motor" and look at the margin ads.


    • #3
      Forrest is on the ball with his reply IF everyone plays the game but the cheap import stuff doesn't.

      Horsepower is measured as roughly 750 watts equals 1 HP so if you have 1.5Kw you have a 2HP motor.
      This is taking it that it's efficient.

      One bar of an electric fire also consumes about 750 watts [ depand on model ] so using the horspower formula we could say this is 1 HP, but it doesn't rotate.

      What you get with the import crap is on a 2Hp motor you probably get 1 horsepowers worth of rotation and one horsepowers worth of heating due to bad design or manufacture.

      There is no hard and fast ruling you can apply, possible the best on is go for a makers name instead of stated details.

      There are some good cheap motors out there, a lot are now made in East European countries for well know makers to their spec but still sold at marked up prices. You will also find the same East Europen counteis also make for may manufactures at the same facility and often do ther own model as well.
      ABB motors are now being made in Bulgeria as are the German WEG.

      If you can accepr metric framed motors in your application go for them as they are far cheaper than the larger US framed motors.
      It seems that only the US use the larger framed 9 wire motors now and these are at a premium price.
      As an example I bought 10 German WEG, two horse power 440v 3 phase motors a couple of months ago , delivered, for 20 UKP each, about $32 each.

      John S.

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


      • #4
        I have had good luck with this source for cheap motors. They sell a range of brands.

        I have no connection with them. Good luck.