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Factory Power From Total Current

  1. Mar 11, 2013 #1
    1.A small factory utilizes the standard 120V/Hz voltage. When all the heavy machinery is operational, the total electric current flowing into the factory is 1.2 amperes. The phase angle between the voltage and current waveforms is measured to be 2.1 radians. Find the real power dissipated by the factory. Round off your answer to two decimal places.



    2. P = Vrms x Irms x pf



    3.Vrms = 120, Irms = 1.2?, I converted 2.1 to degrees and got 120.321. I thought it would just be 120 x 1.2 x cos(120.321).
     
  2. jcsd
  3. Mar 12, 2013 #2

    NascentOxygen

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    Staff: Mentor

    Are you sure you have these figures correct? A current of 1.2A is unrealistic. That's the current for a pair of small light globes.

    The phase angle should lie between 0 and -90 degrees. If it indeed is -120 degrees, this implies that the factory is generating power.

    Is this likely to be a trick question?
     
  4. Mar 12, 2013 #3

    NascentOxygen

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    Staff: Mentor

    From your identical thread: that 1.2A can be assumed to be RMS, that's how AC quantities are usually specified (by default).
     
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