Phasor Diagram

Discussion in 'Homework Help' started by tinhnho, Nov 16, 2004.

  1. tinhnho

    Thread Starter Active Member

    Aug 31, 2004
    34
    0
    hi everyone


    Given V1 = -.41800 - .51918j and V2 = -0.27126 - .35264j
    The question is: " Does V1 lead or lag V2 ? "
    The answer in the book is : Delta_phi = -1.27 degree -- if possitive V1 leads

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    My question is how do i know that V1 lead or lag V2 ?

    Thanks everyone
     
  2. vineethbs

    Well-Known Member

    Nov 14, 2004
    56
    0
    well,first of all V1 and V2 wud be the phasor representations of sinusoidal signals
    in order to find which one leads or lags the other one , u have to find the phase angle between them . Consider the time t=0 for analysis .

    now for both v1 and v2 the real and imag parts are -ive ,so they lie in the third quadrant.
    phase angle of v1 is 180 + arctan(.51918/.41800) = 231.16 deg
    phase angle of v2 is 180 + arctan(.35264/.27126) = 232.43 deg

    now the phase difference is 1.27 deg

    abt the answer in the book :
    Now the phasor difference shows that V2 leads V1 by 1.27 deg

    now as i said before , the phasors aren't fully given , so we don't know whether it is
    v1(or v2) x e^(jwt) or v1 (or v2) x e^(-jwt)

    now if we are taking postive freq or anticlockwise direction of rotation then v2 leads v1 else v1 leads v2 .
     
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