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 Ω)

C = S-344 Capacitor Bank (1uF to 63uF)

Documents

Lab 5 Formal