American University of Sharjah
College of Engineering
Electrical Engineering Program
ELE 212R
Electric Circuits II
Lab
Lab #1
Introduction to Three-Phase (3-) Power Systems
Group Information
Course: ELE212L-
10
Section -1
ID
Name of Student
Number
1 Omar Rashed
B00095230
2 Nawaf AlNatoor
B00095442
3 Shehab Shaban
B00092409
Abstract
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This lab report contains the outcomes and analysis of an experiment designed to investigate the
measuring procedures of a three-phase power system. The experiment aimed to offer a thorough
knowledge of numerous characteristics of three-phase systems, such as phase sequence, balanced
operation, and voltage and current behavior. The lab technique included measuring the line-to-neutral
and line-to-line voltage magnitudes, calculating the phase angles and % error of the readings, and
creating a phasor diagram to show the six source voltages. In Part 1, the voltage magnitude and phase
angle of the source were calculated. In Part 2, loads were connected in Wye configuration to measure
actual and reactive power and current. In Part 3, loads were linked in Delta configuration to measure
the total real and reactive power absorbed by the load. The data was evaluated to establish if the source
was balanced or imbalanced, as well as the quality of the readings. The lab report finishes with a
discussion of the experiment's problems and a summary of the findings.
Objectives
 To learn the measurement techniques of three-phase power system.
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 To understand phase sequence.
 To understand three-phase balanced operation.
 To understand voltage and current in the three-phase system.
CAUTION
You will be working with high voltage (>200V) capable of supplying high currents. Use extreme caution when making
the measurements! As a precaution, the lab instructor will inspect your circuit connections prior to switching ON the
power and performing measurement.
Equipment
#
1
2
3
4
5
Description
Three phase power supply
Phase angle meter
Three phase inductive load
Three phase ammeter
Three phase Watt/VAR meter
Module No.
EMS 8821
EMS 8451
EMS 8321
EMS 8425
EMS 8446
Procedure:
Part 1 Find Voltage magnitude and phase angle of the source:
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Qty.
1
1
1
1
1
(Note for this part (Table 1) do not connect any cable)
(a) Turn ON the 3- power supply and adjust the phase
voltage to 220V using onboard voltmeter (Select 4-N).
(b) Using the onboard voltmeter, measure the line-to-line and
the line-to-neutral voltage magnitudes for the three phases
and record your data in Table 1.
Quantity
Value
VAN (4-N)
220
VBN (5-N)
221
VCN (6-N)
220
VAB (4-5)
380
VBC (5-6)
384
VCA (6-4)
385
Table 1
Fig. 1 Onboard Voltmeter
Q1) Does your data indicate the expected relationship between line-to-line and line-to-neutral voltage
magnitudes?
Yes – since the line to line and the line to neutral voltage magnitudes are all in the same
range within each other , it shows a relationship
1.
Using A-phase line-to-neutral voltage (V4-N) as
reference, measure the phase angles and write your
readings in Table 2. Also determine the percentage error
of your measurement compared to theoretical values.
Quantity
Value
Lag/Lead
AN
0
0
%Error (Phase angle AN)= (|0-0|/0) * 100% = 0%
BN
120
lag
% Error (Phase angle BN )= (|0-0|/0) * 100% = 0%
CN
120
lead
% Error (Phase angle CN )= (|0-0|/0) * 100% = 0%
2.
Measure the phase angle of all the line-to-line voltages.
Record your data in Table 3 and determine the percentage error of your measurement compared to
theoretical values.
% Error (Phase angle AB) = (|27-30|/30) * 100=10%
% Error (Phase angle BC )= (|90-90|/90) * 100= 0%
% Error (Phase angle CA)= (|150-150|/150) * 100= 0%
% Error (Phase angle BA)= (|150-150|/150) * 100= 0%
% Error (Phase angle CB)= (|90-90|/90) * 100= 0%
% Error (Phase angle AC)= (|28-30|/30) * 100= 6.67%
3.
Table 2
Construct a phasor diagram indicating all six-source
voltages.
Quantity
Value
AB
27
lead
BC
90
Lag
CA
150
lead
BA
150
Lag
CB
90
Lead
AC
28
Lag
Table 3
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Lag/Lead
VCN
VCA
VAB
VAN
VBN
VBC
Q2) Is the source operating with positive or negative phase sequence?
Positive phase sequence , as the angles we get when we add and subtract 120, follows the ABC sequence,
which is the positive phase sequence.
Q3) Does your phasor diagram look like as you expect? State why or why not.
Yes, the phasor diagram demonstrates a balanced three-phase system with the anticipated line-to-neutral and
line-to-line voltages and phase angles, which match the theoretical values and show the anticipated phase
sequence.
The phasor diagram displays an angle of about 120 degrees between the phase voltages and about 30 degrees
between the line voltages, which is typical of a balanced three-phase system.
Q4) Is the source balanced or unbalanced? Give reason for your response.
They are balanced as the phase angles and magnitudes are almost equal and theres almost a 120 degree
difference between every phase, which is the condition for a balanced source.
Part 2 WYE Configuration Load:
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Ensure that the power is switched ‘OFF’, connect the load in accordance to the block diagram as shown in
Figure 2. Ask the lab instructor to check your circuit before switching “ON’.
3-ϕ Inductive
Load
3-
Power
Supply
3- 
Ammeter
3-  Load
3- 
Watt/VAR
7.5H, 2400,
Meter
0.1A
N
N
Figure 2
4.
Measure and record in Table 4 the total real and reactive power
absorbed by the load along with flow of line current.
(a) Using known complex power and current, compute and record the
equivalent Y-connected impedance of the load.
ZY = -----------------------------------+ J------------------------------------- ()
Z = 10+j65/(3*0.075^2) = 592.6 + j3851.9
(b) Using the known voltage and calculated impedance, compute the
three phase complex power absorbed by the load.
Compare your computed result with the measured results.
S= 3(Vp2)/Z*=
3(220)2/(592.6 -j3851.9) = 5.66 + j36.8 =
37.3<81.3 degree
Quantity
Value
P3
10
Q3
65
IA
0.075
IB
0.075
IC
0.075
Table 4
%error = 10+j65 = 65.76<81.25
65.76 – 37.3 / 65.76 *100 = 43.3 %
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Part 3 Delta Configuration Load:
5.
Ensure that the power is switched ‘OFF’, connect the load in accordance to the block diagram as shown in
Figure 3. Make sure neutral wire is not connected to delta connected load. Ask the lab instructor to check
your circuit before switching “ON’.
3-
Power
Supply
3- 
Ammeter
3-ϕ Inductive
3- Load
 Load
3- 
Watt/VAR
7.5H, 2400,
Meter
0.1A
Figure 3
6.
7.
8.
Turn ON the 3- power supply and adjust the phase voltage V4N to 220V.
Measure and record in Table 5, the total real and reactive power absorbed by the load.
Using Ammeter, measure the line and the phase current for each individual load and record your data in
Table 5. To measure the phase current, you may move the 3- Ammeter from its showing position to be
connected in series with each load.
Note:- If using 1.5 Amp scale on ammeter, first number after 0 is 0.25 and then increment of 0.05.
Check Appendix A
Q5) Does your data indicate the expected relationship between line
and the phase current magnitudes?
Yes, since the relationship between the line and phase currents
are the same
Quantity
Value
P3
25
Q3
145
Ia (Line current)
0.27
Ib
0.26
Ic
0.27
IA (Phase Current)
0.175
(b) Using the known voltage and calculated impedance, compute
the three-phase complex power absorbed by the load.
IB
0.175
S= 3 x |VP|^2 / ZY*= 3(380)^2/272.1-j1578)=45.97+266j
270 <80.5
IC
0.175
(a) Using known complex power and current compute and
record the equivalent delta-connected impedance of the load
Z = ---------------------------+ J--------------------------- ()
S=25+j145 or 147 <80.2
Z=25+j145/3*(0.175)^2=272.1+j1578 1601.28 <80.21
Compare your computed result with the measured results.
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Table 5
%error= 270-147/147*100=83.6%
9.
Using Analog voltmeter measure voltages across the delta
connected load and record the data in table 6.
Use Analog Voltmeter
across the load
Quantity
Value
VAB
360
VBC
365
VCA
365
Table 6
Q6) For the same load components, which connection type do you think consumes more power? Explain your
answer.
A delta connection type consumes more power than a wye connection as it absorbs more power for the same
load components (line voltage in delta is sqrt3 *phase voltage, which leads to more power).
Note:- Submit Lab Report






Your conclusion must reflect all the measurements and data.
If you have finished your Experiment turn OFF the supply.
Rotate the power supply knob fully anti clockwise.
Place the cables back properly, while removing the cable hold it from chord.
If you have placed any papers, books, water bottles take it back.
Make your place neat and clean before you leave the lab.
Appendix A
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0.25
The first
value is
0.25 if using
1.5A scale
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Conclusion
The experiment's objective was to help us understand the components and processes of a three-phase power
system, and how to read the values and set it up. To evaluate actual and reactive power and current, the lab
technique required connecting loads in Wye and Delta configurations, measuring voltage magnitudes and phase
angles, and creating a phasor diagram. The experiment's outcomes were examined to evaluate the measurement
accuracy and determine if the source was balanced or imbalanced. The correctness of the measurements was
demonstrated by the load's calculated equivalent impedances, which agreed with the observed data. A solid
understanding of three-phase power systems and measuring methods was obtained from the experiment. The
experiment's results aligned with expectations, indicating that the measuring techniques employed were
effective. The findings have practical applications in three-phase power systems.
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