How do I calculate firing angle of single phase RL circuit?

Discussion in 'Homework Help' started by fazlio, May 19, 2009.

  1. fazlio

    Thread Starter New Member

    May 19, 2009
    2
    0
    Hi. How do I calculate the firing angle of single phase ac/ac full wave if i am only given resistive load 1.5 ohm, Vs 120v, 60 Hz and oP 7.5Kw? Thanks Guys
     
  2. jasperthecat

    Member

    Mar 26, 2009
    20
    0
    fazlio

    Try googling "thyristor firing angle"

    I got this first up

    www.reseeds.com/thyristor%20control%20question.doc

    The question only mentions a resistive load not a RL circuit
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    There is no "simple" way of solving this but it can be done numerically.

    If the power at firing angle 0 degree is Po and the power at firing angle α is Pα

    then it can be shown that

    Pα/Po=k=1-α/Pi + (1/(2*Pi))*sin(2α) [with α in radians]

    Since you are given Pα=7500W and you can work out Po (thereby giving you the required value of k) you can then solve for the value of α using some numerical approximation technique (or graphical method) or a programmable calculator (if you have one) might have an equation solver function.
     
  4. fazlio

    Thread Starter New Member

    May 19, 2009
    2
    0
    Great! Thanx a lot guys!! Cheers!
     
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