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Quick question on 3 phase before my final

  1. Apr 27, 2008 #1
    Quick question on 3 phase before my final!!

    1. The problem statement, all variables and given/known data

    In equations for 3 phase power there is an angle that is mentioned, but I dont know if this is the angle of the impedance or another angle. Im a little confused. The equations are below.



    2. Relevant equations
    P=(VrmsIrms)cos([tex]\theta[/tex])
    Q=(VrmsIrms)sin([tex]\theta[/tex])


    Any help?
     
  2. jcsd
  3. Apr 29, 2008 #2

    PhanthomJay

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    I'm certainly not an electrical expert, but the angle you are referring to is the phase angle betwen the voltage and the current, where [tex]cos\theta = power factor[/tex]. For purely resistive loads, theta is 0, hence the power factor is unity, and there is no reactive power Q. However, I don't quite understand your equation, since typically ,for power transmsission, [tex] P= \sqrt3(V)(I)cos\theta [/tex]. That's about it for my electrical knowledge.
     
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