Transcript Revision AC

REVISION
Things you should know
Things you have learned in SEE1003
Things I EXPECT you to know !
1
Knows how to write expressions for sinusoidal waveforms
v(t) = ? sin(t +
v(t)
Vm
?)
v(t) = ? cos(t + ? )
o
t
o
1
Revision
2
AC circuit analysis deals with phasors and impedances
Phasors: A complex number containing information on
magnitude and phase of a sinusoidal voltage or current
A cos (t  o)

A  o
A sin (t  o)

A  (o  90o)
Impedance: A ratio between voltage and current phasors – it
is a complex number but NOT a phasor
Z = R + jX
You MUST know how to deal with complex number
2
Revision
Z = R + jX
3
Revision
Z = R + jX
Impedance
Reactance
Resistance
Im
Pure resistor: Z = R
Re
Im
Re
1
1
 j
Pure capacitor: Z =
C
jC
Pure inductor: Z = jL
Im
Re
4
Revision
Z = R + jX
Impedance
Reactance
Resistance
Inductive impedance: Z = R + jX
|Z|
X
R
R
Capacitive impedance: Z = R - jX
-X
|Z|
5
Revision
3
You must know how to draw phasor diagrams
V1
V2
V1 = 2030o V
V2 = 10120o V
I1 =
5-60o A
120o
30o
-60o
I1
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Revision
4
Perform nodal and mesh analysis in frequency domain
Steps involved are exactly similar to DC anaysis
However in AC, we deal with complex numbers
7
Revision
5
Do you know CIVIL ?
For Capacitor,C, I leads V by 90 degrees
For Inductor, L, V leads I by 90 degrees
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