App-26
IM 253710-01E
Appendix 7 Power Basics (Power/Harmonics/Three Constants Related to the AC Circuit)
For the mean value, since taking the average over one period of a sine wave results
in zero, the mean is determined using the absolute value over one period of the
signal. As with the rms value, if the mean value of the current of the instantaneous
value i = I
m
sin
ω
t is expressed as I
mn
, then,
=
1
π
0
2
π
I
m
2
2
π
i d
ω
t =
I
mn
= Mean over one period of i
This relationship is the same for the voltage of the sine wave.
The maximum value, rms value, and mean value of an AC sine wave are related in
the following way. These values are used to calculate the crest factor and the form
factor which are used to determine the trend of an AC signal.
Crest factor =
Maximum value
Rms value
Form factor =
Rms value
Mean value