CEN201: Electric Circuits
Lab Experiment 2
The Superposition Theorem
Star - Delta Transformation
Prepared By:
Eng. Yazan Barham
Objectives
1. Use practical measurements to verify the superposition theorem.
2. Calculate currents in a ’T’ network using superposition.
3. Determine currents in a simple network using superposition.
4. Verify star-delta equivalence by measurement.
5. Recognize star-delta/delta-star formulae.
Required Equipment
(a) Advanced Electronics
Experiment Platform
(b) Electrical Networks Board
(c) Multimeter
Figure 1: List of equipment
Introduction
This lab is divided into two exercises. The first exercise will be experimentally studying the superposition theorem and
verifying it. On the second exercise you will be working in the Star-Delta transformation.
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Procedure
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Exercise 1: The Superposition Theorem
In this exercise, you are going to experiment the superposition theorem and verify it practically by measuring the currents
using the circuit in Figure 2:
Figure 2: Super Position Circuit
1. Make sure the Module Power Supply is OFF.
2. Connect shorting links between sockets 3.2 & 3.3, 3.5 & 3.6 and 3.8 & 3.9 as shown in Figure 3.
3. Set the multimeter on the DC voltage range and measure the voltage across the 12V source, -5V source and R8.
Record your measurements in Table 1.
4. Set the multimeter on the DC current range and measure the the current passing by each resistor. Record your
results in Table 2.
5. Remove the shorting link between sockets 3.8 & 3.9 and reconnect it between sockets 3.8 & 3.11.
6. Measure the currents again with the 12V source only and record your results in Table 2.
7. Return the shorting link between sockets 3.8 & 3.9 instead of sockets 3.8 & 3.11.
8. Remove the shorting link between sockets 3.2 & 3.3 and reconnect it between sockets 3.3 & 3.4.
9. Measure the currents again with the -5V source only connected and record your results in Table 2.
10. Complete Table 2
Figure 3: Super Position Connections
2
V1
(Across 12V Source)
Voltages (V)
V2
(Across -5V Source)
V3(Across R8)
Table 1: Superposition Results for the Voltages
Current (mA)
-5V Source
Only
12V Source
Only
Measured
Calculated
I6a =
I7a =
I8a =
I6a =
I7a =
I8a =
% of
Error
Measured
Calculated
I6b =
I7b =
I8b =
I6b =
I7b =
I8b =
Both Sources
% of
Error
Measured
Calculated
I6 =
I7 =
I8 =
I6 =
I7 =
I8 =
% of
Error
Table 2: Superposition Results for the Current
• Question 1.1: How did having the sources in the same direction affect the voltages across R8?
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• Question 1.2: What is the relation between the total current passing by a resistor and the currents caused
by the individual sources according to the superposition theorem?
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Exercise 2: Star-Delta Transformation
In this exercise, you are going to study the star-delta transformation and verify their formulas using the circuit in Figure 4:
Figure 4: Star-Delta Circuit
1. Make sure the Module Power Supply is OFF.
2. Find the equivalent Delta connected circuit to the Star connected circuit you have by measuring the resistance
between each two sockets and record your results in Table 3.
3. Measure the resistances between each two sockets in the Delta connected circuit and record your results in Table 3.
Star Connected Circuit
Resistance Resistance Resistance
Between
Between
Between
A’ and B’ A’ and C’ B’ and C’
Ω
Ω
Ω
Delta Connected Circuit
Resistance Resistance Resistance
Between
Between
Between
A and B
A and C
B and C
Ω
Ω
Ω
Table 3: Star-Delta Transformation Results
• Question 1.1: Are the two circuits a Delta-Star transformation to each others? Why?
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