Lab 5 Formal

ET-3051
Electronic Signals
Laboratory 5, Experiment 4
Power in Alternating Current Circuits
Milwaukee School Of Engineering
Performed By: Alex Kremnitzer
Performed On: 10/06/2010
Lab Redo: 10/14/2010
Lab Partners: None
Submitted To: Professor B. Petted
Due On: 10/20/2010
Submitted On: 10/21/2010

ET-3051 Lab 5 Experiment 4 1
MILWAUKEE SCHOOL OF ENGINEERING ET-3051 Fall 2010
Table of Contents
Executive Summary …………………………………………………………………………2
Introduction …………………………………………………………………………………. 3
Theoretical Solution ………………………………………………………………………….4
Results………………………………………………………………………………………….12
Analysis of Results …………………………………………………………………………….14
Conclusion……………………………………………………………………………………...17
Reference………………………………………………………………………………………18

Executive Summary
This experiment proved the concept of the power factor correction. By adding a
capacitance to the circuit, there was a reduction of the power factor angle and a resulting
reduction of the total current used by the circuit. This over time amounts to savings in power
consumption of varying degree depending on the original circuit’s components. Motors and
fluorescent lighting are common items in which a power factor correction can result in savings.

Introduction
This laboratory experiment is to show that in an AC circuit, there is both real and reactive
power. The real power is that which is dissipated in a resistor, where the voltage and current are
in phase. The reactive power is that which is dissipated in a capacitor or inductor and there is a
phase shift between the voltage and current. For the circuit performed, the inductor’s reactive
component causes the current to lag by 90 degrees in respect to the voltage. The energy is stored
in the inductor’s magnetic field.
To change the energy being used due to the imaginary impedance to be from the real
impedance means having the voltage and current in phase. The removal of the phase shift is
achieved by performing a power factor correct. This is essentially adding a reactive component
to cancel out the circuit’s reactive impedance, achieving only real power. The power factor is the
ratio of real power to the reactive power. A zero power factor means all circuit power is reactive
and a value of 1 means all the power is real.
As the power factor approaches 1, the circuit voltage and current approaches being in
phase while the power dissipated in the circuit approaches becoming real. The total circuit
current is also reducing. This is important as higher currents means more energy is being
consumed, causing an increase in both operating costs and for equipment needed to handle the
higher currents.

Theoretical Solution
The original circuit, shown in figure 1, has only an inductor as the reactive component so
in theory to perform the power factor correction on the circuit, the added component must be
capacitive.
Figure 1: Circuit schematic
Table 1: Nominal Component Values
The circuit was analyzed using the formulas shown below with the ideal circuit
component values. Then the formulas were recalculated using the measured circuit values, both
with and with-out the iron rods in the inductor’s core. The value of corrective capacitance was
also calculated from the power factor correction of the circuit using the three conditions. The
values of capacitance were used to calculate the new values of the power factor corrected circuit.

Figure 2 shows the relationship between real and reactive power.

Figure 2 Power Factor Triangle

Results
The circuit in Figure 1 was constructed. The Fluke 43 Power Quality Analyzer was used
to measure both the real and reactive power components of the circuit first without the iron rods
in the inductor core and no power factor correction capacitance applied. Then a power factor
correction was applied through the use of the capacitor bank. The capacitor bank switches were
turned on until the correct amount of capacitance was achieved to show as close to a power
factor value of 1 on the Fluke 43 Power Quality Analyzer. This corrective value of capacitance
was measured and recorded. The test procedure was then repeated with the iron rods used in the
core of the inductor.
Measured Data
Table 2 Measured Component Values
Table 3 Measured Circuit Values

Figure 3 Amplitude Waveforms (No Core in Inductor)
Figure 4 Phase Shift (No Core in Inductor)
Figure 5 Amplitude Waveforms (With Core in Inductor)
Figure 6 Phase Shift (With Iron Core in Inductor)

Analysis of Results
Component Value Comparison
Table 4 Comparison of Component Values
Circuit Values Comparisons
Table 5 Comparison of Calculated Ideal
Circuit Values to Measured Values (No Core in Inductor)
Table 6 Comparison of Calculated Ideal
Circuit Values to Measured Values (With Core in Inductor)

Table 7 Comparison of Calculated Actual
Circuit Values to Measured Values (No Core in Inductor)
Table 8 Comparison of Calculated Actual
Circuit Values to Measured Values (With Core in Inductor)

There were some large errors between the measured and the calculated values. However,
the measured data shows a decrease in total circuit current with the application of the power
factor correction capacitance. The measured reactive power decreased with an associated
increase of real power with the power factor correction. Another factor is the inclusion of the
winding resistance of L in the calculations. This does account for the calculated total current
being higher than the actual measured value. With the winding resistance of L1 factored into the
circuit, the increased total resistance would cause a lower total circuit current.
For the circuit when the iron rods were placed in the inductor’s core, achieving a
duplication of the power factor with the same settings on the capacitance bank was not
achievable. The S-344 capacitance bank was inconsistent in results on the Fluke model 43 power
quality analyzer when the same switch positions were duplicated. This may be a result of wear
on the switch contact resistance. Also the calculated values using the actual measured values for
circuit calculations had a Vs value larger than the nominal value, reducing the overall calculated
circuit current used for subsequent calculations.

Conclusion
This experiment did prove the concept of the power factor correction. As the circuit was
corrected for the power factor angle the measured current used by the circuit decreased. There
was also a resulting decrease in reactive power and an increase in the real power. This shows that
by applying the proper amount of capacitance in the circuit to counter the reactance from the
inductor, the phase angle caused is reduced, bringing the circuit closer to consuming only real
power and running (pf = 1) more efficient.

Reference
Test Equipment List:
Fluke Model 43 Power Quality Analyzer
Agilent Model 34401A Multimeter
Fluke Model PM6304 RCL Meter
Agilent Model 54662 Oscilloscope
Circuit Component List:
VS= 120VAC/24VAC Power Transformer
L = S-344 Inductor 100mH
R = S-344 Parallel Resistor Bank (All Switched Up = 60 )
C = S-344 Capacitor Bank (1uF to 63uF)

Lab 5 Formal

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