Voltampere

Discussion in 'General Electronics Chat' started by allied, May 20, 2007.

  1. allied

    Thread Starter Active Member

    Mar 11, 2007
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    Could anyone kindly explain in DETAILS........... the difference between the watts and voltampere.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    The wikipedia link I originally posted here was faulty. I would refer you to recca02's reply several replies ahead for a proper wikipedia link. Thanks go out to recca02 for posting a proper link.

    hgmjr
     
  3. allied

    Thread Starter Active Member

    Mar 11, 2007
    37
    0
    I plan to buy a UPS...I notice in the specification that the watts and voltampere is not the same. ( ex. 1000va , 650 watts). I call the RS component techsupport about this they not able to explain it to me they told me the will call me back to explain it but they not call me. Im just want to know the relation of watts and va on the UPS.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
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    Did the wikipedia article, I cited earlier, not explain it for you?

    hgmjr
     
  5. allied

    Thread Starter Active Member

    Mar 11, 2007
    37
    0
    hi HGMJR

    Could you explain it to me in details..thanks
     
  6. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    The term "Watt" is most often associated with DC power consumption while the term "Volt-ampere" is most often associated with AC power consumption. The both are equivalent since they have the same units.

    In AC power, the term "Volt-Ampere" is frequently used in the expression for "Apparent power" by combining it with the phase relationship between the current and the voltage. The term for "apparent power" is "volt-ampere reactive".

    I would recommend that you read up the wiki article I cited and read up on the details.

    hgmjr
     
  7. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    I have given you an answer over in this other thread: http://forum.allaboutcircuits.com/showthread.php?t=3986

    I would recommend for clarity that we keep all further discussion on this topic in this thread. Thanks.

    Dave
     
  8. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    for me the link by hgmjr didnt work probably the same for you so im reposting the link (the page contains some more links in blue colour :) try them too)
    http://en.wikipedia.org/wiki/Volt-ampere

    edit:consider a load of some power factor cos(phi)
    then the active power is given by W = VA.cos(phi)
    where VA is the apparent power(as already explained) obtained by multiplication of voltage and current at full load.
    sometimes ratings are specified in terms of VA since it remains constant irrespective of load power factor as in case of transformers.
     
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