leading or lagging power factor

Discussion in 'Homework Help' started by gisdude, Aug 2, 2015.

  1. gisdude

    Thread Starter Member

    Oct 30, 2008
    Hi all, sorry to revive this topice, but I have a question.
    If a generator is producing 500MW and 200MVAR, it the generator?
    1. Leading
    2. Lagging
    3. Underexcited

    Intuitively, I would say "Lagging", but if I make a power triangle from these 2 quantities, HOW DOES ONE TELL IF IT'S LEADING VS. LAGGING?

    You can get the cos of the angle, but that doesn't tell me if current is leading or lagging, right?

    Many thanks
  2. crutschow


    Mar 14, 2008
    Deleted post.
    Last edited: Aug 3, 2015
  3. gisdude

    Thread Starter Member

    Oct 30, 2008
    Reactive power, typically, is less than Real power. If you have a lot of VARS on the system, then you're going to be losing Real power. That's why on transmission systems the utility will install capacitor banks, 600kvar, 1200kvar, etc, to keep the power factor closer to unity.
  4. Ramussons

    Active Member

    May 3, 2013
    500 MW is the Real Power (MVA Real) and 200 MVA is the Reactive part (MVA Reactive). The power produced by the generator would be 538.5 MVA.

    With the given input, it will be not possible to say whether this Reactive Power is Leading or Lagging. Generally, with loads like Motors and Transformers, it will be Lagging.

    I see no relation to the other 2 options given ....... Underexited; Dropping (what does this mean?)

    The only connection with "exitation" is that "an over exited Synchronous Motor exhibits a Leading Power Factor" and use of such are known as "Synchronous Capacitors".