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Thread: out of ideas

  1. #40
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    Quote Originally Posted by Chris_Worthingt View Post
    So your saying an oversized/undersized/caveatting blower motor will not run hot/over amped? I find this hard to believe http://lmgtfy.com/

    Why would one, not consider the designed curve as a tool for diagnosis to a problem with the blower motor/section?

    The OP has apparently checked the incoming power supply, so now we just blindly change parts at random till it works? makes no sense to me, I would check the fundamentals and go from there ;-)
    He ran the motor with no pulley, no load at all, and it still drew excessive amperage.

    Blower curves are for later.

  2. #41
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    I am with JP on this one. Especially now that we have a different motor that has burned out with very limited usage. Power source problem of some sort.

  3. #42
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    Don't smack me, but are the motors wired correct for the voltage?

    Also, are you using a true RMS amp clamp?
    God Bless our Veterans

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  4. #43
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    Quote Originally Posted by jpsmith1cm View Post
    He ran the motor with no pulley, no load at all, and it still drew excessive amperage.

    Blower curves are for later.
    OK, I'm a jerk, but,,,,, playing the devils advocate :-)

    you have a motor not doing jack for? awhile, it will over-heat and become toast over time, fact.

    Asssssssuming, it is wired correctly and the applied voltage is correct, which really, how difficult is it to check? Why wouldn't this have not popped up sooner in this thread by the OP, I think he covered that, but perhaps he is a bonehead?

    You have in your diagnostic arsenal;

    1) a meter to check volts and amps
    2) design parameters

    Am I missing something here?

  5. #44
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    Quote Originally Posted by Chris_Worthingt View Post
    OK, I'm a jerk, but,,,,, playing the devils advocate :-)

    you have a motor not doing jack for? awhile, it will over-heat and become toast over time, fact.

    Asssssssuming, it is wired correctly and the applied voltage is correct, which really, how difficult is it to check? Why wouldn't this have not popped up sooner in this thread by the OP, I think he covered that, but perhaps he is a bonehead?

    You have in your diagnostic arsenal;

    1) a meter to check volts and amps
    2) design parameters

    Am I missing something here?
    Go back and read the op's first post. He's now at the point where a third motor brand new is drawing excessive amps with no load and without ever having had a load on it. He's listed his voltage readings and amp readings. The fan isn't even in the picture at this point.

  6. #45
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    Block the return air with cardboard- 12.6 amps. run without belt, 12.6 A. 4.15" sheave, motor loaded as much as I can, 12.6 amps. 3.25" sheave, 12.6 A
    by OP

    and the rest of info is????????? i,e static?, are we doing we anything? i.e. a diff? the curve says? spinning wheels?

  7. #46
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  8. #47
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    A single phase motor will run FLA and slightly higher when unloaded and/or caveatting is my point and fact.

    Google motor power factors and you will see what I am referring too, it is often a misconception that a scernario like this with a larger HP motor then is needed will resolve issues like these, often it is the smaller "loaded" motor that is is needed.

    hmmmm, you have a 1 ton unit and it needs a 1/8th HP condenser fan motor,,,,, you only have a 5 hp motor, but with the same Frame, RPM, yada yada yada can you use it??? why NOT???

    See where I'm going here?

  9. #48
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    Quote Originally Posted by Chris_Worthingt View Post
    A single phase motor will run FLA and slightly higher when unloaded and/or caveatting is my point and fact.

    Google motor power factors and you will see what I am referring too, it is often a misconception that a scernario like this with a larger HP motor then is needed will resolve issues like these, often it is the smaller "loaded" motor that is is needed.

    hmmmm, you have a 1 ton unit and it needs a 1/8th HP condenser fan motor,,,,, you only have a 5 hp motor, but with the same Frame, RPM, yada yada yada can you use it??? why NOT???

    See where I'm going here?
    To be clear, are you saying a single phase induction fan motor will pull Full Load Amps if it is not under any load?

  10. #49
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    Run it through his calculator to check and see if the brake horsepower checks out for your application

    http://www.delhi-industries.com/Engi...ps/fanlaws.asp
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  11. #50
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    Quote Originally Posted by Chris_Worthingt View Post
    A single phase motor will run FLA and slightly higher when unloaded and/or caveatting is my point and fact.

    Google motor power factors and you will see what I am referring too, it is often a misconception that a scernario like this with a larger HP motor then is needed will resolve issues like these, often it is the smaller "loaded" motor that is is needed.

    hmmmm, you have a 1 ton unit and it needs a 1/8th HP condenser fan motor,,,,, you only have a 5 hp motor, but with the same Frame, RPM, yada yada yada can you use it??? why NOT???

    See where I'm going here?
    Regardless of horsepower, NO electric motor running totally disconnected from load should pull nameplate FLA. So, no, I don't see where you're going. Explain.

  12. #51
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    Are the power system voltages to ground correct and closely balanced?
    Any difference between neutral and ground?
    Usually a system that loses its ground reference and begins to float doesn't burn up motors, though. You'd usually see funny arcing conduit joints and reports of people getting shocked. Or maybe dimming lights and that kind of stuff.

    Some kind of intermittent loss of connection at a lug, a breaker stab, a loose busbar?
    God Bless our Veterans

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  13. #52
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    Quote Originally Posted by Chris_Worthingt View Post
    A single phase motor will run FLA and slightly higher when unloaded and/or caveatting is my point and fact.

    Google motor power factors and you will see what I am referring too, it is often a misconception that a scernario like this with a larger HP motor then is needed will resolve issues like these, often it is the smaller "loaded" motor that is is needed.

    hmmmm, you have a 1 ton unit and it needs a 1/8th HP condenser fan motor,,,,, you only have a 5 hp motor, but with the same Frame, RPM, yada yada yada can you use it??? why NOT???

    See where I'm going here?
    Exactly.

    Start by trying to block off the supply partially somehow and you will see that the amperage will decrease.

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