
24-16 Electrical Variables
e previous expression is, in fact, a general denition of power factor for any current and voltage wave-
forms
. F
or
t
he
s
pecial
c
ase
o
f
si
nusoidal
v
oltage
a
nd
c
urrents,
P
F
r
educes
to c
os(ϕ)
.
e
re
ar
e
a nu
mber
of wa
ys
to me
asure
th
e
po
wer
fa
ctor
. On
e
wa
y
is to us
e
a wa
ttmeter
to me
asure
th
e
re
al
av
erage
po
wer
an
d
a vo
ltmeter
an
d
an am
meter
to me
asure
th
e
rm
s
vo
ltage
an
d
cu
rrent,
re
spec-
tively
. e po
wer
fa
ctor
is th
en
de
termined
ac
cording
to Eq
uation
24.22. i
s
is pr
obably
th
e
mo
st
e
ec-
tive
wa
y
wh
en
th
e
cu
rrents
an
d/or
vo
ltages
ar
e
no
nsinusoidal
. i
s
pr
ocedure
ca
n
ea
sily
be im
plemented
wi
th
“d
igital
po
wer
me
ters
.” e ...