f. cos R
T
φ
R
Z
V
V
The electrical power circuit the product the instantaneous values of
the voltage and current. Figure 10. Inductors
store energy magnetic field and capacitors electric field.Alternating current theory and electrical machines
201
For (a):
X
fC
X
C
C 6
1
2
( )
1
2 50Hz F
53.f.2
Ω
∴ Ω
Ω
For (c):
I
V
Z
I
(A)
230 V
113. 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.c. 10.
. 10.f. circuit voltage and current are phase. From the trigonometry the impedance triangle shown
in Fig. also equal to:
p. circuit the power consumed given the product the volt-
age and current, because d.f.05 113.) defined the
cosine the phase angle between
the current and voltage.7, p.f.8
Waveform for the a.05
π
Ω
∴
π
Ω
For (b):
Z X
Z
2
2 2
( )
(100 (53.
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. power purely inductive
and purely capacitive circuits.f.This shows that inductors and capacitors store energy during one part of
the voltage cycle and feed back into the supply later the cycle.
Power
Power
I
I
V
V
Pure inductor
Pure capacitor
FIGURE 10.8 shows the voltage and current waveform
for pure inductor and pure capacitor.03A
∴
Ω
Power and power factor
Power factor (p. The power waveform obtained from
the product and every instant the cycle.2
2.f.
If the current lags the voltage shown Fig. 10. cos
φ
Definition
Power factor (p.c.5, say that the p. 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.) defined the cosine the phase angle between the
current and voltage:
p.c.6, the p. is
lagging, and the current leads the voltage shown Fig. is
said leading
