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Quick question about transformer circuit

  1. May 8, 2016 #1
    1. The problem statement, all variables and given/known data

    Can someone inform me wheher my solution is correct?
    2i89cmd.jpg

    2. Relevant equations
    V1 = E2 * (10^-3)/2*(10^-3) = 0.001
    V2 = E1
    Ra = (R2+R3) = 0.02
    Rb = R1 = 30
    n = (1/100)
    n^2 = (1/100)^2
    3. The attempt at a solution
    I1 = (V'1 - V2)/(Ra'+Rb)
    I1 = (0.001/n - 230)/(0.02/n^2 + 30)
    I1=-0.9995652174
     
  2. jcsd
  3. May 8, 2016 #2

    NascentOxygen

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    Staff: Mentor

    Why is this sum equated to 20mΩ ?
     
  4. May 8, 2016 #3
    Yup, my error.
    Anyway, after looking at problem again I solved it in different way. I think this way makes more sense (at least to me).
    Previous solution did not count ).
    So, can you tell me whether this one correct?

    I2 = current over R2
    a=100/1=100
    I2=aI1
    V2=V1/a
    V2 = (-I1R1+E)/a
    V2 = (-I2R2)+(E2* (R2/(R1+R2)))
    (-I2R2)+(E2* (R2/(R1+R2)))=(-I1R1+E)/a

    -(10^-3)I2+(0.6667)=-(3/10)I1+2.30

    -0.1I1+(0.6667)=-(3/100)I1+2.30
    -0.1I1+(3/10)I1=+2.30-(0.6667)
    0.2I1 = 1.6333
    I1 = 8.1665
     
  5. May 8, 2016 #4

    NascentOxygen

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    loki4000, you really don't need anyone else to check your answer---because you can do the check yourself. Substitute your answer and see what the figures look like.

    For example, you determined the primary current to be a little over 8A? What voltage loss would that give you across the primary's resistance, and does that sound reasonable?
     
  6. May 8, 2016 #5

    NascentOxygen

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    Staff: Mentor

    I think you should first explain in words how you will go about solving this. It would help you, and it will be easier for others to follow what you are doing.
     
  7. May 8, 2016 #6
    Never mind. I solved it. Thanx for reply anyway.
     
  8. May 8, 2016 #7

    NascentOxygen

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    What answer did you get for the primary current?
     
  9. May 12, 2016 #8
    I1=0.5 A
     
  10. May 13, 2016 #9

    NascentOxygen

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    Staff: Mentor

    That is my answer, too. :cool:
     
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