Basic Electrical Circuits & Machines (EE-107)
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Transcript of Basic Electrical Circuits & Machines (EE-107)
Basic Electrical Circuits & Machines (EE-107)
Course TeacherShaheena Noor
Assistant ProfessorComputer Engineering Department
Sir Syed University of Engineering & Technology.
Basic Nodal and Mesh analysis
In this chapter, we introduce two different ways to view electric
circuits.
Basic Nodal and Mesh Analysis
• Nodal Analysis:– It is based on KCL.
• Mesh Analysis:– It is based on KVL.
• Both methods allow to construct equations for a wide variety of circuits.
Nodal Analysis
Method:• Use when (normally) multiple sources are
present.• Convert voltage sources into current sources.• Identify all the nodes and choose a reference
node.• All the nodes (except reference node) are
then numbered and their corresponding voltages are designated. V1, V2, . . .
Steps:1. We will assume V1 > V2 > V3... > 0.2. Draw an arrow beside each passive component (resistor)
showing the direction that current flows through it (made on the assumption made in step 1. For example)
3. The arrow is drawn from V1 towards V2, because current
always flow from the higher voltage node to the lower voltage node.
4. Label each arrow with the current it represents, expressed in term of node voltages.
5. Write KCL at each node and solve the equations
Nodal Analysis
V1
10 Ohm
V2
V1
10 Ohm
V2
• For the circuit given below, compute the voltage across each current source.
Nodal AnalysisDrill Problem 4.1 (Page 71)
4A5 Ohm2A
7 Ohm
V1
3 Ohm
V215 Ohm
• For the circuit given below, compute the voltage across each current source.
Nodal Analysis(Drill Problem 4.2) Page 74
7A
Reference Node
4 Ohm1 Ohm
3 Ohm 5 Ohm3A
2 Ohm
Mesh Analysis• Mesh analysis requires that all the sources in a
circuit be voltage source.
• The next step is to draw closed loops in the circuit, each loop representing a path around which KVL will be written.
• The direction of each loop is arbitrary. • It may be either clockwise or counter clockwise.
Mesh Analysis• It is convenient to think of each loop as
representing a current that flows around the loop and we designate each by an appropriate symbol I1, I2 and so on.
• These loop currents are the unknowns in the set of simultaneous equations that results when KVL is written around each loop.
• Thus the number of unknown (loop currents) is the same as the number of equations.
Mesh AnalysisDrill Problem 4.5 (page 80)
• Determine i1 and i2 in the circuit shown below.
14 Ohm
5 Ohm
i1
10 Ohm
6V5V
i2
5 Ohm
Mesh AnalysisDrill Problem 4.6 (page 80)
• Determine i1 and i2 in the circuit given below:
5 Ohm
10 Ohm3V
10V
4 Ohm
i1
7 Ohm
i29 Ohm
1 Ohm