Series-parallel Combination AC circuits Worksheet

Discussion in 'Feedback and Suggestions' started by Unregistered, May 16, 2010.

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  1. Unregistered

    Thread Starter Guest

    Okay I may be wrong with this, but it seems there is an error in

    AC power
    http://www.allaboutcircuits.com/worksheets/acpower.html

    Question 31, part 2.

    Here are my calculations for working out the line current:
    1/Xc + 1/Za = 1 / Ztot
    (2*60*pi*270x10^-6)<-90 + 1/(5<34) = 1/Ztot
    Z tot = 1 / ((2*60*pi*270x10^-6)<-90 + 1/(5<34))
    Z tot = 3.698 < 52.183

    This gives a line current of V/Z = I
    I = 240 / (3.698 < 52.183)
    I = 64.8999 < -52.18

    The supposed answer is I line = 39.87 A
    It seems as if calculations went like this:

    1/Xc + 1/Za = 1 / Ztot
    (2*60*pi*270x10^-6)<90 + 1/(5<34) = 1/Ztot **Note 90, not -90
    Z tot = 1 / ((2*60*pi*270x10^-6)<90 + 1/(5<34))
    Z tot = 6.02 < 3.47

    I = V / Z
    I = 39.87 < - 3 .47.

    As far as I'm aware a capacitor with value 10 F has
    Xc = (1 / (2pi*f*10)) < -90.

    Please let me know if this is infact an error in the answer, or an error on my part.

    Regards,
    Steve
     
  2. Spoon

    Member

    May 18, 2009
    12
    0
    I think you are incorrectly changing the 90,
    will look into it soon
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    We really can't interact with non-members. If you wish to continue, please register with us.

    Thanks for the interest.
     
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