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Old October 4th 04, 11:45 PM
Steve Nosko
 
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Yadda, yadda, yadda


The term "RMS POWER" while not technically correct for anything practical is
tossed about and I suspect it is 'meant' to mean true or average power as
generally understood by those schooled in the field. One of the reasons for
formal training (or understanding of that training) is so we have
terminology which we have in common. One word or phrase relates to the same
concept for everyone in the discussion.


"Peak-to-peak power" is quite meaningless. P-P voltage and current can be
measured, but power is a second order quantity requiring voltage and current
and an in-phase component as well...and multiplication of these quantities
(that's what makes it second order). This takes care of the phase
relationships and when the voltage goes negative, the current does (the
in-phase component does) and two negatives make a positive and you again
have positive power. There is NO amount of voltage or current which occurs
which is the P-P value. This is only in the eye of the beholder who chooses
to relate two parts of a waveform which occur at different times.


Question:

In a pulsed situation like a common bridge rectifier, capacitor input filter
DC supply, can the true power be determined by measuring the Irms and Vrms
(on the AC side) and doing P = Irms X Vrms ???

Anybody sure enough to say???


--
Steve N, K,9;d, c. i My email has no u's.