Power Factor in DC

Discussion in 'General Electronics Chat' started by iulian28ti, Jan 19, 2010.

  1. iulian28ti

    Thread Starter Member

    Dec 4, 2009
    Well, basically what i'm interested in is active FPC.

    But first i have a few questions.

    First about power line resistance.

    Basically, if you have a linear load, and that load is equal to the line resistance (yeah, big big big load, i know:D, but it's just an abstract example), then we will have a power factor of 0.5 ? In other words, does the line resistance contribute to power factor loss ?

    Or is power factor an issue only in AC lines driving a capacitive or inductive
    load ?

    And finally, i did a bit of reading on active PFC, but i don't understand how exactly can a boost converter help increase PFC. So how ?

    Any input is appreciated
  2. iulian28ti

    Thread Starter Member

    Dec 4, 2009
    Well, meanwhile i did a bit more reading and from what i can understand , PFC is more about stabilizing input power . Am i right ?
  3. Papabravo


    Feb 24, 2006
    In a DC circuit there are no reactive components. The current and voltage are always in phase, which is another way of saying that the phase difference between the current and voltage is zero degress, and the cosine of zero is one. I know this is hard but remember -- In a DC circuit the power factor is always one, just one, and never anything but one.

    In an AC circuit, depending on the components the power factor can take the same values as the cosine of the phase angle between the current and votage waveforms. That reange would be from zero to one.
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