PPT: Thevenin’s & Norton’s Theorems | Basic Electrical Technology - Electrical Engineering (EE) PDF Download

 Page 1


Thevenin’s and Norton’s theorems
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Thevenin’s and Norton’s theorems
Flow of presentation
ØStatement of Thevnin’s theorem
ØExamples of Thevnin’s theorem
ØStatement of Norton’s theorem
ØExamples of Norton’s theorem
Page 3


Thevenin’s and Norton’s theorems
Flow of presentation
ØStatement of Thevnin’s theorem
ØExamples of Thevnin’s theorem
ØStatement of Norton’s theorem
ØExamples of Norton’s theorem
THEVENIN’S THEOREM:
Consider the following:
Network
1
Network
2


A
B
Figure 1:  Coupled networks.
For purposes of discussion, at this point, we consider
that both networks are composed of resistors and
independent voltage and current sources
Page 4


Thevenin’s and Norton’s theorems
Flow of presentation
ØStatement of Thevnin’s theorem
ØExamples of Thevnin’s theorem
ØStatement of Norton’s theorem
ØExamples of Norton’s theorem
THEVENIN’S THEOREM:
Consider the following:
Network
1
Network
2


A
B
Figure 1:  Coupled networks.
For purposes of discussion, at this point, we consider
that both networks are composed of resistors and
independent voltage and current sources
THEVENIN’S THEOREM:
Suppose Network 2 is detached from Network 1 and
we focus temporarily only on Network 1.
Network
1


A
B
Figure 2:  Network 1, open-circuited.
Network 1 can be as complicated in structure as one
can imagine.  Maybe 45 meshes, 387 resistors, 91
voltage sources and 39 current sources.
Page 5


Thevenin’s and Norton’s theorems
Flow of presentation
ØStatement of Thevnin’s theorem
ØExamples of Thevnin’s theorem
ØStatement of Norton’s theorem
ØExamples of Norton’s theorem
THEVENIN’S THEOREM:
Consider the following:
Network
1
Network
2


A
B
Figure 1:  Coupled networks.
For purposes of discussion, at this point, we consider
that both networks are composed of resistors and
independent voltage and current sources
THEVENIN’S THEOREM:
Suppose Network 2 is detached from Network 1 and
we focus temporarily only on Network 1.
Network
1


A
B
Figure 2:  Network 1, open-circuited.
Network 1 can be as complicated in structure as one
can imagine.  Maybe 45 meshes, 387 resistors, 91
voltage sources and 39 current sources.
Network
1


A
B
THEVENIN’S THEOREM:
Now place a voltmeter across terminals A-B and
read the voltage.  We call this the open-circuit voltage.
No matter how complicated Network 1 is, we read one
voltage.  It is either positive at A, (with respect to B)
or negative at A.
We call this voltage V
os
and we also call it V
THEVENIN
= V
TH