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Sum of branch currents more than total current?

  1. May 20, 2013 #1
    1. The problem statement, all variables and given/known data
    An impedance of 7-2jΩ and an impedance of 4+2jΩ and a current source of 97.5A are all connected in parallel. Find the individual branch currents.
    2. Relevant equations

    Current-divider rule:

    I1=I*Z1/(Z1+Z2) (only have to consider the magnitudes of the impedances, not the angle)

    3. The attempt at a solution

    I've obtained a value of I1=39.54A and I2=64.53A. However, these currents sum up to 104.07A, whereas the current source is supplying a current of only 97.5A. Why is there a discrepancy?
     
    Last edited: May 20, 2013
  2. jcsd
  3. May 20, 2013 #2
    For complex current I1 and I2 it's true that I1 + I2 = (97.5 + j*0) A, but it doesn't follow that |I1| + |I2| = |(97.5 + j*0)| A
     
  4. May 21, 2013 #3
    Oh, I see. My bad.

    Thank you very much, milesyoung!
     
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