KodKodKod said:
Dear all,
Thank you very much for your comments! (especially to John)
We have re-written the article
http://www.kodkodkod.com/files/powerfactor.htm
I still think you need to start with a question (the opening
"question" is just a phrase) and say what displacement power factor
is. The current drawn by a reactive load has two components. One is
power consumed by the load (or converted to some of the form of power,
like mechanical). The second component represents energy that is
stored by the reactance and then returned to the power source, twice
per cycle. So the line current represents power passing one way, from
source to load, and also energy sloshing back and forth between source
and load as short term loans. The combination of both energy flows
produces relative a phase shift between the line voltage and line
current.
If the reactance is inductive, the energy is borrowed mostly after the
voltage peaks so the current peaks lag the voltage peaks. If the
reactance is capacitive, the energy is borrowed mostly on the way up
to the peaks, so the current peaks lead the voltage peaks.
Then the math shows the details of these processes.