3 phase power formula

Discussion in 'Electronic Basics' started by erthlink, Feb 25, 2004.

  1. erthlink

    erthlink Guest

    the three phase power formula goes like this:

    V * I * 1.732 * PF

    where V - voltage, I - current, PF - power factor

    a 3 phase generator set to 120/208 V with amperage values of 24A, 26A, 22A
    at each phase.. PF is 0.8

    which V value should i use? do i take the average current (I) or do i add
    them up?
     
    erthlink, Feb 25, 2004
    #1
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  2. erthlink wrote:
    >
    > the three phase power formula goes like this:
    >
    > V * I * 1.732 * PF
    >
    > where V - voltage, I - current, PF - power factor
    >
    > a 3 phase generator set to 120/208 V with amperage values of 24A, 26A, 22A
    > at each phase.. PF is 0.8
    >
    > which V value should i use? do i take the average current (I) or do i add
    > them up?


    If the three currents listed are the 3 line to neutral currents (not
    line to line current) then you just use the single phase formula 3
    times and add the results. 120V*A*PF

    --
    John Popelish
     
    John Popelish, Feb 25, 2004
    #2
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  3. erthlink

    Lord Erdel Guest

    which brings me to another question.. what am i measuring when i use a
    clamp-on ammeter? am i correct in stating this equation then?

    P = V[phase-ground] * ( I[phase1] + I[phase2] + I[phase3]) * PF * 1.732

    assuming i have the same phase voltages across the board of course..

    > If the three currents listed are the 3 line to neutral currents (not
    > line to line current) then you just use the single phase formula 3
    > times and add the results. 120V*A*PF
    >
    > --
    > John Popelish
     
    Lord Erdel, Feb 25, 2004
    #3
  4. erthlink

    Don Kelly Guest

    "erthlink" <> wrote in message
    news:DHS_b.20461$...
    > the three phase power formula goes like this:
    >
    > V * I * 1.732 * PF
    >
    > where V - voltage, I - current, PF - power factor
    >
    > a 3 phase generator set to 120/208 V with amperage values of 24A, 26A, 22A
    > at each phase.. PF is 0.8
    >
    > which V value should i use? do i take the average current (I) or do i add
    > them up?
    >

    If the currents are the same in all 3 phases then use the line to line
    voltage (208V). Otherwise use 120*I*pf 3 times and add them up as John has
    indicated. Actually using 208*1.732*24A*pf will probalby be close enough for
    government work.

    --
    Don Kelly

    remove the urine to answer
     
    Don Kelly, Feb 25, 2004
    #4
  5. erthlink

    Guest

    On Wed, 25 Feb 2004 01:16:19 GMT erthlink <> wrote:

    | the three phase power formula goes like this:
    |
    | V * I * 1.732 * PF
    |
    | where V - voltage, I - current, PF - power factor
    |
    | a 3 phase generator set to 120/208 V with amperage values of 24A, 26A, 22A
    | at each phase.. PF is 0.8
    |
    | which V value should i use? do i take the average current (I) or do i add
    | them up?

    Is that 0.8 PF the rating of the generator, or the actual load?

    --
    -----------------------------------------------------------------------------
    | Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
    | (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
    -----------------------------------------------------------------------------
     
    , Feb 25, 2004
    #5
  6. erthlink

    Lord Erdel Guest


    > Is that 0.8 PF the rating of the generator, or the actual load?
    >


    0.8 is my arbitrary value for PF..
     
    Lord Erdel, Feb 25, 2004
    #6
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