Three phase system question

Discussion in 'Homework Help' started by Manuel Faria, May 5, 2016.

  1. Manuel Faria

    Thread Starter New Member

    May 5, 2016
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    I have the following circuit. Three phase generator, direct sequence

    Screen Shot 2016-05-05 at 20.16.42.png
    The goal is to calculate i3.

    I know that e3(t)=200sqrt2cos(wt)
    C=1mF w=1000rad/s
    P=10kW Q=10kVAr
    P*=10kW Q*=-5KVAr



    What I'm doing:
    e1(t)=200sqrt2cos(wt-120)
    e2(t)=200sqrt2cos(wt-240)

    i3+i3'(capacitor)=i3''(load)+i3'''(load*)

    i3'=V2(phase)/Zc
    i3''=S/(sqrt(3)*VL)
    i3'''=S*/(sqrt(3)*VL)
    My doubt is in i3'' and i3'''
    i3'=200sqrt2e^j(-240º)/j=283e^j(30)
    i3''=10000sqrt(2)e^j(45)/sqrt(3)sqrt(3)200sqrt(2)e^j(30)=1,6e^j(15)
    i3'''=11180e^j(27)/sqrt(3)200sqrt(2)e^j(30)=22,8e^j(-3)

    Is this procedure correct? Thanks
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    I don't see anything that indicates whether or not the 3-phase load is balanced. Is it?
     
  3. Manuel Faria

    Thread Starter New Member

    May 5, 2016
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    0
    It just says that the network three phase network is powered by three symmetric direct voltages.
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    Then you don't have much of a realistic choice but to assume that it is balance, but you should be sure to make a note that you are making that assumption.
     
    Manuel Faria likes this.
  5. Manuel Faria

    Thread Starter New Member

    May 5, 2016
    3
    0
    So the way I'm thinking it is correct?
     
  6. WBahn

    Moderator

    Mar 31, 2012
    17,757
    4,800
    Possibly. I'm just not willing to wade through your work unless you go back and track your units through the work properly.
     
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