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Electric Circuits and Networks, Ist Edition by Pearson
book

Electric Circuits and Networks, Ist Edition by Pearson

by K. S. Suresh Kumar
May 2024
Intermediate to advanced content levelIntermediate to advanced
840 pages
45h 20m
English
Pearson India
Content preview from Electric Circuits and Networks, Ist Edition by Pearson
8.9 APPARENT POWER, ACTIVE POWER, REACTIVE POWER AND
POWER FACTOR
Consider a sinusoidal voltage source v(t) V
m
cos
ω
t delivering power to a resistive load R.
The current in the resistor is i(t) I
m
cos
ω
t, where I
m
V
m
/R.
The instantaneous power is p(t) V
m
I
m
cos
2
ω
t 0.5V
m
I
m
0.5V
m
I
m
cos2
ω
t W. The
first term is a constant and the second term produces an average of zero over a cycle. Therefore,
the average power delivered to the resistor is 0.5V
m
I
m
0.5V
m
2
/R 0.5I
m
2
R. The average
power can be expressed as V
rms
I
rms
in terms of rms values of voltage and current. Thus, a
sinusoidal voltage/current is only as effective as a DC voltage/current of magnitude ...
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Publisher Resources

ISBN: 9781299447028