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Calculating energy transfer

  1. Jun 10, 2012 #1
    Hallo,

    I want to calculate energy transfer from an electromagnet that consumes 12W of electricity thats about 12J/S of energy transfered to: A. a non-magnetic rotor shaft( Do I have to include the magnetic field information?)
    B. permanent magnet rotor shaft

    * Electric energy > Mechanical energy transfer calculation please*

    Could you relate this to the formula W = F x D? On both rotors?

    Detailed answers required please!

    Best Regards,

    Dream,
     
    Last edited: Jun 10, 2012
  2. jcsd
  3. Jun 10, 2012 #2

    NascentOxygen

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    Staff: Mentor

    How did you determine that 12W of electricity equates to 720J of energy transferred?

    How should there be a difference between the magnetic and non-magnetic rotors?

    Is this related to a homework question? If so, what is the question precisely?
     
  4. Jun 10, 2012 #3
    Sorry for that mistake I adjusted it and fixed it...
    The question is not homework related I'm trying to calculate "work" transfer from one form A(ELECTRICITY) to B(MECHANICAL).
    I find permanent magnets being more efficient then others.
     
  5. Jun 10, 2012 #4

    NascentOxygen

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    Staff: Mentor

    Motors with a wound rotor would ultimately be less energy efficient than one using industry's best permanent magnets for the rotor field. There may be other criteria apart from efficiency that must be taken into consideration.
     
  6. Jun 10, 2012 #5
    Thats what I thought! Permanent magnets are highly efficient for this system and could transfer the energy well. However, calculating this transfer is what I desire could you build up this formula/equation?
     
  7. Jun 11, 2012 #6
    Makes sense why it would be more efficient to. What are the other criteria's considered?

    Um, I guess you and I are in the same spot huh?
     
  8. Jun 11, 2012 #7

    NascentOxygen

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    Staff: Mentor

    You are not asking the right questions here, which suggests that you have a very shaky grasp of what is needed to tackle this exercise. It is not possible to work out what you are seeking, based on what you have provided.

    To determine efficiency, you need to know both power in and power out. Nowhere have you made any mention of the load the motor is driving. There's a rotational motion equation you must commit to memory, see: http://www.me.mtu.edu/~wjendres/ProductRealization1Course/DC_Motor_Calculations.pdf
     
  9. Jun 11, 2012 #8
    I don't want to calculate efficiency alone. I'd like to calculate the exact energy transfer from point A"Electricity" to point B "Mechanical rotation" what factors do I have to look at to do so

    I understand energy "IN" is one of the factors what are else? all the factors in the system.

    Thanks for that link really good stuff!
     
  10. Jun 11, 2012 #9

    NascentOxygen

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    Are you talking about the various energy losses? If not, then I don't know what you mean.
     
  11. Jun 11, 2012 #10
    Isn't energy being converted from electricity to mechanical energy?

    Look at it this way: I have a motor inside of it is an electromagnet that consumes electricity "INPUT" that creates and magnetic field that attracts/repels that rotor in the motor that produces rotation or mechanical rotation "OUTPUT".

    I want to calculate that energy conversion listed above.

    What factors do I need to build up the equation?
     
  12. Jun 11, 2012 #11

    russ_watters

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    Unless you are doing a simple conservation of energy relation (Ein = Eout + loss), this isn't something can be easily done. You'd need to calculate the magnetic forces within the motor, which requires a computer model to do with any kind of accuracy.

    What are you trying to accomplish with this? From your other thread, it sounds like you want to try to design a motor from scratch, which doesn't seem like a useful thing to do, even if it was something you could do well. It sounded from your other thread like you are trying to solve a problem (low efficiency in existing motors) that doesn't exist.
     
  13. Jun 12, 2012 #12
    I'm really trying to break down the electric motor and study everything in it! I do want to calculate everything. I'd like the calculate the magnetic forces within the motor and Ein = Eout + losses.

    All in all I want to calculate every single step within the motor.
    What program do I need to calculate the magnetic forces?
    And yes I do want to build a motor from scratch I've already placed everything! Just need to do the math/physics before I send and build it.

    One thing though what do you mean with the low efficiency? Didn't get that part.
     
  14. Jun 12, 2012 #13
    If someones could add all the factors I need so I can start measuring and calculating it one by one then build up the final equation. One my confusions and main concerns is the magnetic fields... What programs,ways,etc... Can I calculate it?
     
  15. Jun 13, 2012 #14
    So far I've found the equation for the magnetic forces within the motor.

    How could I calculate "Ein = Eout + the losses"
    (Electricity > Mechanical conversion)
     
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