Please could someone explain what the cos means

Discussion in 'Homework Help' started by ElecNerd, Jan 2, 2011.

  1. ElecNerd

    Thread Starter New Member

    Jan 2, 2011
    20
    0
    Hi,

    Whilst I understand the following in terms of identifying the phase and line voltages etc please could someone advise me what I would put into the calculator for cosθ as detailed below. I seem to understand it and then they throw this in for good measure :).

    In case of delta conneted load in above fig(a) the total active power is equal to three times the power of one phase.[​IMG]
    [​IMG]

    Since the line current in the balanced delta connected loads is
    [​IMG]
    substituting this eq the total active power becomes
    [​IMG]

    Thank you very much for your help!
     
  2. edgetrigger

    Member

    Dec 19, 2010
    133
    19
    cosθ is the phase agle between the current and the voltage. If you are calculating for a resistor just enter 0 in the calculator, or cos0 = 1 , you could ignore it for a resistor
     
  3. edgetrigger

    Member

    Dec 19, 2010
    133
    19
    furhter for a pure inductor or a capcitor θ = 90. Mind you, you have to set the calculator to degree mode before doing calculations. If it is in radian then calculation will go for a toss.
     
    Last edited: Jan 2, 2011
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    The cosine of the phase between the voltage and the current is also referred by the term "power factor".

    hgmjr
     
  5. ElecNerd

    Thread Starter New Member

    Jan 2, 2011
    20
    0
    Thanks everyone for taking the time to answer this for me - much appreciated :)
     
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