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  1. #1
    Join Date
    Aug 2004
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    Default Phase converter for a shear

    I'm stuck with single phase 220 and am in the process of buying a hydraulic shear that has a 20 HP motor on it, What size phase converter do I need.

    I've talked to a few people and I'm being told that I need to go 1-1/2 times the size of the motor so I will need a 30Hp phase converter.

    Is anyone running a shear or press brake off a phase converter.

  2. #2
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    Default

    Ed Conley
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  3. #3
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    Default

    For a single machine, wouldn't it be easier and cheaper to simply change the motor? Since you are still buying single-phase power, only advantage to a phase converter I can see is the ability to buy other 3-phase equipment, and run them off the same phase converter.
    Obviously, I'm just a hack-artist, you shouldn't be listening to anything I say .....

  4. #4
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    Default

    I've never seen a single phase motor bigger than 7.5 Hp so let me go and see.

  5. #5
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    Isn't your overhead crane 3 phase? Or didn't that come about.
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  6. #6
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    Sep 2009
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    Default Variable frequency drives

    In addition to the rotating converters, which I think you are referencing, there is an electronic alternative. Some Variable Frequency Drive units have the ability to change single phase to three phase. I think that would be a less expensive solution. With a VFD you can also incorporate soft starts, etc. You would have to do some research, and change some of the controls, but this is another approach. You don't need the variable frequency, but the unit would do what you want, just leave the frequency at 60 hz.

    There are companies that you could call and have them help you size a VFD.

    With today's electronics, I would sure look at an electronic alternative. But if you can get a 30 hp motor cheap that might be the way to go.

    20HP is a large motor, of course, so would need an appropriately sized rotary converter or VFD.

    Note that 20 HP at 240 volts is around 70 amps, and that does not include the start-up current, which could be 4 times the steady state current or more. Do you have 400 amp service to your shop?

    Richard
    Last edited by raferguson; 03-01-2013 at 05:36 PM.

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