05 113.) defined the
cosine the phase angle between
the current and voltage.8
Waveform for the a. The power waveform obtained from
the product and every instant the cycle.
If the current lags the voltage shown Fig. From the trigonometry the impedance triangle shown
in Fig. also equal to:
p.f.f. 10.05
π
Ω
∴
π
Ω
For (b):
Z X
Z
2
2 2
( )
(100 (53.f.2
2.f. circuit the power consumed given the product the volt-
age and current, because d.6, the p.5, say that the p.03A
∴
Ω
Power and power factor
Power factor (p.f.
In electric circuit more power taken from the supply than fed back
into it, since some power dissipated the resistance the circuit, and
therefore:
P )
In any d.Alternating current theory and electrical machines
201
For (a):
X
fC
X
C
C 6
1
2
( )
1
2 50Hz F
53.This shows that inductors and capacitors store energy during one part of
the voltage cycle and feed back into the supply later the cycle. 10. power purely inductive
and purely capacitive circuits.c.f. 10.
Power
Power
I
I
V
V
Pure inductor
Pure capacitor
FIGURE 10.2
Ω
∴ Ω
Ω
For (c):
I
V
Z
I
(A)
230 V
113.) defined the cosine the phase angle between the
current and voltage:
p.f. Figure 10. cos R
T
φ
R
Z
V
V
The electrical power circuit the product the instantaneous values of
the voltage and current.7, p.8 shows the voltage and current waveform
for pure inductor and pure capacitor. can seen that the
power waveform reverses every quarter cycle, indicating that energy alter-
nately being fed into and taken out the inductor and capacitor. is
lagging, and the current leads the voltage shown Fig.
.c. Inductors
store energy magnetic field and capacitors electric field. circuit voltage and current are phase.c. When con-
sidered over one complete cycle, the positive and negative portions are equal,
showing that the average power consumed pure inductor capacitor is
zero. is
said leading. cos
φ
Definition
Power factor (p
