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AC CIRCUIT ANALYSIS
Introduction
SEE 1003 Section 08
Nik Din Muhamad
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PHASOR DIAGRAM
A phasor diagram is a diagram illustrating how the
various phasors in a particular situation relate to one
another. The diagram is simply a pictorial way of
viewing the voltages and currents.
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PHASOR CONCEPT 1
A series RLC in the Figure below has the voltages
across each element as follows:
|VR| =50 V
|VL| =50 V
|VC| =100 V
(i) What is the magnitude of Vs
(ii) Determine R, L and C if the current flow in the
circuit is 20.
R
Vs
f =100 Hz
L
C
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PHASOR CONCEPT 2
A parallel RLC in the Figure below has the currents
through each element as follows:
|IR| =7.5 A
|IL| =10 A
|IC| = 15 A
(i) What is the magnitude of Is
(ii) Determine R, L and C if the voltage across the
parallel elements is V =1000 V.
Is
f = 50 Hz
R
L
C
+
V
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PHASOR CONCEPT 3
A series RL is connected to a 240 V ac source. If the
voltage across the resistor is 150 V, find the voltage
across the inductor.
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PHASOR CONCEPT 4
What value of w will cause Vo to be zero. Determine
magnitude of the voltage across capacitor for that
frequency.
+
2W
5 mF
Vo
50 cos wt
20 mH
-
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PHASOR CONCEPT 5
What magnitude of Ic will cause VS in phase with IS.
Determine value of the capacitor C.
IS
VS = 240 V
f = 50 Hz
IRL
IC
IC
VS
IRL= 560
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