lab report power quality 1

8/18/2019 Lab Report Power Quality 1

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LAB REPORT

KKKZ 4044 POWER QUALITY LAB 1

SESSION 2015/2016

SINGLE PHASE POWER QUALITY MACHINE

NAME : ABDUL HAKIM BIN ABDULLAH

MATRIC ID : A 141188LECTURER : PROF. DR. M. A. HANNAN

DEMO : MOHD FIRDAUS HAFIDZUDDIN


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1.0

ABSTRACT

Single phase machine normally is not very sensitive as three phase machine since the load

for single phase usually consume low voltage demand compared to load in the industrial

area which demand high voltage in its load system. Moreover, the load for single phase

are not seem to be affected if power quality problem such as voltage sag, voltage swell orflicker occurs. But it may affected if the high power load was connected in the electrical

system such as air conditioning, refrigerator and microwave was used at the same time

using inappropriate electrical connection. In other cases, circuit breaker in industrial

factories may tripped if the voltage supply not enough for load consumption in three

phase machine because it is very sensitive to any power quality problem in the electrical

system. Fluke 434 Power Quality Analyzer is an electrical equipment which is used in

this experiment to locate, predict, prevent and troubleshoot problems in three- and

single-phase power distribution systems. Troubleshooting is faster with on-screen display

of trends and captured events, even while background recording continues. The new IEC

(International Electrotechnical Commission) standards for transient, flicker, harmonics

and power quality are built right in to take the guess work out of power quality. In this

experiment, we have used NE9102 Distribution Trainer and Induction Motor as load to

test the Fluke 434 Power Quality Analyzer to view the effect on dips & swells, transients,

flicker and harmonics.

2.0 INTRODUCTION

A utility may define power quality as reliability and show statistics demonstrating that its

system is 99.98 percent reliable. Criteria established by regulatory agencies are usually in

this vein. A manufacturer of load equipment may define power quality as thosecharacteristics of the power supply that enable the equipment to work properly. These

characteristics can be very different for different criteria. Power quality is ultimately a

consumer-driven issue, and the end user’s point of reference takes precedence. In general,

power quality problem can be defined as any occurrence manifested in voltage, current or

frequency deviations which results in failure or frequency deviations which results in

failure or misoperation of end-use equipment.

There are many misunderstandings regarding the causes of power quality problems.

Figure 1 below show the result of the survey conducted by Courtesy of Georgia Power

Company. Power quality sources can cause from inside and outside of the electrical

system. For examples single phase to ground shorts on the distribution system, lightning,

weather, utility switching, equipment failure, human error, common mode transients from

load switching, grounding problem, load interactions, harmonic generating loads and total

harmonic distortions.


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Figure 1 : Results of a survey on the causes of power quality problems. (Courtesy of

Georgia Power Co.)

In a single phase electrical system, there are many types of power quality problem may

occurs. Voltage sag, voltage swell, transient, harmonic distortion, electrical noise,

flickering, notching and spikes are example of power quality problem in electrical system.

There are a few method which can be used to overcome this power quality problem. For

example, voltage sag problem can be solve by using mitigating devices such as

ferroresonant transformer, magnetic synthesizers, active series compensator, UPS systems,

motor generator set, dynamic voltage restorer, static transfer switch, flywheel energy

storage systems and superconductor magnetic energy storage (SMES) device.

3.0 METHODOLOGY

1. Phase A(L1) conductor in main switchboard panel was clamped with current clamp of

Fluke 434.

2. Banana-inputs was connected to ground, phase A(L1) and neutral conductor for voltage

connection. Phase 2(L2) was connected to investigate the line-to-line voltage.

3. Choose single phase split phase configuration on the analyzer.

4. Configure the nominal voltage and frequency of the single phase power system for the

analyzer.

5. Press the Menu button to enter measurement menu of the analyzer.

6. Select Volts/Amps/Hertz option to measure the voltage, current, frequency and crest

factor for phase L1, L2 and Neutral of single phase power system before introducing any

disturbance in the system. Observe the numerical values of the Volts/Amps/Hertz table.


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Then, observe the waveforms trends of the voltage and current of the single phase power

system.

7. Repeat step 5 and select Dips & Swells option to measure and record the numerical

values and waveform trends of voltage and current for phase L1, L2 and Neutral of single

phase power system before and after the disturbance injected into the power system.8. Switch on the distribution trainer, induction motor set and DC compound wound motor

set consecutively for a few seconds to create a power quality disturbance in the system.

Observe the waveform trends of the phases and neutral voltages and current.

9. Record and compare the minimum and nominal values of each set of measurement.

10. Repeat step 7 to select Harmonics option to measure and record the numerical values

and waveform trends of the voltage and current harmonics and Total Harmonics

Disturbance (THD) value for phase L1, L2 and Neutral of single phase power system

before and after the disturbance is injected into the power system. Repeat step 8. Observe

the bar graphs of the phase and neutral current and voltage and record the THD value.

11. Repeat step 7 and select Flicker option. Leave the analyzer for measurement without

any disturbance for one minutes to obtain the short-term flicker value Pst (1 min). Turn

on and off the lighting switch of the fluorescent lamps on the table in the laboratory

repeatedly and continuously for 1 minutes. Then, record the short-term flicker value Pst

(1 min) and observe the flicker waveform trend. Then, wait another 1 minute for whole

system settling down and record the short-term flicker value Pst (1 min) and observe

flicker waveform trend again.

12. Repeat step 7 and select Transients option. Repeat step 8 and observe the current and

voltage waveforms for phase L1, L2 and Neutral of the single phase power system.Record the numerical values appear on the screen.

4.0 RESULTS

4.1 Setup Configuration

Before conducting the experiment we need to configure the nominal voltage and

frequency. Figure 4.1 shows the result of configuring the nominal voltage and frequency

of the single phase power system. The single phase connection from banana-input can beview in the setup configuration as shown in figure 2.


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Figure 2 : Nominal voltage and frequency Figure 3 : Single phase connection

4.2 Volts/Amps/Hertz

Figure 4 : Numerical value for star

connection

Figure 5 : Numerical value for delta

connection

Figure 4 and 5 shows the differences between numerical value of star and delta

connection. In figure 5, the phase L1 and L2 share the same value of their own rms

voltage, peak voltage, crest factor and frequency. Moreover, rms current, peak current and

crest factor for L2 was not displayed in the analyzer screen. Earlier, the nominal

frequency was 50 Hz was decreases to 49.96 Hz. A change in system frequency willcause change in speed of motors, change in magnetizing current will be there for

transformers and induction motors will be affected with change in inductances. A huge

increase will cause increase in harmonic currents and will cause heating of the system

with insulation failure. Frequency of a system also decides the real power balance in a

power system as line parameters will change with change in frequency. Figure 15 shows

the nominal frequency of the single phase power system.


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Figure 6 : Phase L1 Vrms Figure 7 : Phase L1 Irms

Figure 8 : Phase L2 Vrms Figure 9 : Phase L2 Irms

Figure 10 : Phase N Vrms Figure 11 : Phase N Irms


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Figure 12 : Phase L1 I peak Figure 13 : Crest factor

Figure 14 : Phase L2 I peak Figure 15 : Nominal frequency

Figure 16 : Phase N I peak


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4.3 Dips & Swell

Figure 17 : Phase L1 Irms before disturbance Figure 18 : Phase L1 Vrms before disturbance

Figure 19 : Phase L2 Irms before disturbance Figure 20 : Phase L2 Vrms before disturbance

Figure 21 : Phase N Irms before disturbance Figure 22 : Phase N Vrms before disturbance


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Figure 23 : Phase L1 Irms during disturbance Figure 24 : Phase L1 Vrms during disturbance

Figure 25 : Phase L2 Irms during disturbance Figure 26 : Phase L2 Vrms during disturbance

Figure 27 : Phase N Irms during disturbance Figure 28 : Phase N Vrms during disturbance


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Figure 29 : Phase L1 Irms after disturbance Figure 30 : Phase L1 Vrms after disturbance

Figure 31 : Phase L2 Irms after disturbance Figure 32 : Phase L2 Vrms after disturbance

Figure 33 : Phase N Irms after disturbance Figure 34 : Phase N Vrms after disturbance


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Figure 17 until 22 shows the Irms and Vrms of the phase L1, L2 and Neutral before the

power system experienced the load disturbance. From all those figures, we can see the

waveform trends of all the phases are most likely to be smooth without any power quality

problem either voltage dips or swells in this case. But it still occurs in small scale as can

be seen in figure 18 and 20. This problems are causes by the switching on or off the load

from other room at the old faculty building.

Figure 23 until 28 shows the Irms and Vrms of the phase L1, L2 and Neutral during the

power system experienced the load disturbance. Figures in this range had shown a lot of

problem compared to the previous waveform trends before injecting the load disturbance.

All the phases for rms currents and voltages for phase L1, L2 and Neutral during load

disturbance shows a dips and swells in their trends since the load was switch on at the

same room as the fluke meter was measured.

Figure 29 until 34 shows the Irms and Vrms of the phase L1, L2 and Neutral after the power

system experienced the load disturbance. In this situation, the load was switch off but it

seem to have few dips and swells before it was stabilize into its steady state voltage and

current after switching off the load. The correct waveform trends should be taken few

minutes later after switching the load to observe a correct waveform trends.

The 90% level provides an indication of performance for the most sensitive equipment.

The 80% level corresponds to an important break point on the ITI curve and some

sensitive equipment may be susceptible to even short sags at this level. The 70% levelcorresponds to the sensitivity level of a wide group of industrial and commercial

equipment and is probably the most important performance level to specify. The 50%

level is important, especially for the semiconductor industry, since they have adopted a

standard that specifies ride through at this level.

Interruptions affect all customers so it is important to specify this level separately. These

will usually have longer durations than the voltage sags. The first range of durations is up

to 0.2 seconds (12 cycles at 60 Hz). This is the range specified by the semiconductor

industry that equipment should be able to ride through sags as long as the minimum

voltage is above 50%. The second range is up to 0.5 seconds. This corresponds to the

specification in the ITIC standard for equipment ride through as long as the minimum

voltage is above 70%. It is also an important break point in the definition of sag durations

in IEEE 1159 (instantaneous vs. momentary). The third duration range is up to 3 seconds.

This is an important break point in IEEE 1159 and in IEC standards (momentary to

temporary).


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4.4 Harmonics

Figure 35 : THD Voltage before disturbance Figure 36 : THD Voltage after disturbance

Figure 37 : THD current before disturbance Figure 38 : THD current after disturbance

Figure 39 : THD power before disturbance Figure 40 : THD power after disturbance


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Harmonic distortion originates in the nonlinear characteristics of devices and loads on the

power system. Harmonic distortion levels are described by the complete harmonic

spectrum with magnitudes and phase angles of each individual harmonic component. It is

also common to use a single quantity, the total harmonic distortion (THD), as a measure

of the effective value of harmonic distortion.Figure 35 shows the THD voltage with value

1.6% drop to 1.5% after injecting load disturbance as shown in figure 36. In figure 37 and38 the THD current was drop drastically from 187.9% to 43.2%. In a while, figure 39 and

40 shows a drop from 1.0% to 1.1% after injecting the load disturbance into the power

system.

IEEE Standard 519-2014 is a standard developed for utility companies and their

customers in order to limit harmonic content and provide all users with better power

quality. Some of the key areas of the standard are detailed in the following tables. Bear in

mind that dealing with harmonics may still be required, whether or not the goal is to meet

IEEE 519 standards. In low-voltage systems (600 V or less), capacitors are typically thelowest impedance at harmonic frequencies, and experience very high RMS currents and

increased heat which causes them to fail.


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4.5 Flicker

Figure 41 : Before load disturbance Figure 42 : During load disturbance

Figure 43 : Settling down after load

disturbance

Figure 44 : Flicker waveform trend

From figure 41 until 43, the short-term flicker (Pst) for phase L1 increases from 0.08 to

0.14 while decreases from 0.14 to 0.07 for phase L2. The flicker signal is defined by its

rms magnitude expressed as a percent of the fundamental. Voltage flicker is measured

with respect to the sensitivity of the human eye. Typically, magnitudes as low as 0.5

percent can result in perceptible lamp flicker if the frequencies are in the range of 6 to 8

Hz. In this case, the frequency is not affected by the load disturbance then producing the

normal flicker waveform trend without any critical power quality problem as shown in

figure 44.

IEC 61000-4-15 defines the methodology and specifications of instrumentation for

measuring flicker. The IEEE Voltage Flicker Working Group has recently agreed to adopt

this standard as amended for 60 Hz power systems for use in North America. This


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standard devises a simple means of describing the potential for visible light flicker

through voltage measurements. The measurement method simulates the lamp/eye/brain

transfer function and produces a fundamental metric called short-term flicker sensation

(Pst). This value is normalized to 1.0 to represent the level of voltage fluctuations

sufficient to cause noticeable flicker to 50 percent of a sample observing group. Another

measure called long-term flicker sensation (Plt) is often used for the purpose of verifyingcompliance with compatibility levels established by standards bodies and used in utility

power contracts. This value is a longer-term average of Pst samples.

4.6 Transients

Figure 45 : Voltages before load disturbance Figure 46 : Voltages during load disturbance

Figure 47 : Currents before load disturbance Figure 48 : Currents during load disturbance


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Figure 49 : Phase Neutral before disturbance Figure 50 : Phase Neutral during disturbance

Figure 51 : Phase L1 before disturbance Figure 52 : Phase L1 during disturbance

Figure 53 : Phase L2 before disturbance Figure 54 : Phase L2 during disturbance


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Figure 55 : Voltages after load disturbance Figure 56 : Currents after load disturbance

Figure 57 : Phase Neutral after disturbance Figure 58 : Phase L1 after disturbance

Figure 59 : Phase L2 after disturbance Figure 60 : Transients configuration


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Figure 45 until 54, shows the differences of waveform trends between the condition

before injecting the load disturbance and during injected load disturbance. It seem to have

some problem in power quality during the load disturbance as shown in figure 48, 50, 52

and 54. However, the waveform trends of the transient return to be same as before

injecting the load when the load disturbance was turned off.

Transients are power quality disturbances that involve destructive high magnitudes of

current and voltage or even both. It may reach thousands of volts and amps even in low

voltage systems. However, such phenomena only exist in a very short duration from less

than 50 nanoseconds to as long as 50 milliseconds. This is the shortest among power

quality problems, hence, its name. Transients usually include abnormal frequencies,

which could reach to as high as 5 MHz. Transients are also known as surge. According to

IEEE 100, surge is a transient wave of voltage, current or power in an electric circuit.

Other IEEE definitions suggest that it is the part of the change in a variable that

disappears during transition from one steady-state operating condition to another. Suchdescription is too vague, which could be used to describe just about any unusual events

occurring in the electrical system. Moreover, most electrical engineers would refer to the

damped oscillatory transient phenomena in a RLC circuit when hearing such term.

Sources of transients may come from switching activities such as opening and closing of

disconnects on energized lines, capacitor bank switching, reclosing operations, tap

changing on transformers, accidents, human error, animals and bad weather conditions

and neighboring facilities. Damages due to such power quality problems are uncommon

as compared to voltage sags(dips) and interruptions, but when it does occur it is moredestructive. To protect against transients, end-users may use Transient Voltage Surge

Suppressors (TVSS), while utilities install surge arresters.

5.0 DISCUSSION

5.1 Dips & Swell

A voltage sag also known as voltage dips is a decrease to between 0.1 and 0.9 p.u. in rms

voltage or current at the power frequency for durations from 0.5 cycle to 1 min. The power quality community has used the term sag for many years to describe a

short-duration voltage decrease. Although the term has not been formally defined, it has

been increasingly accepted and used by utilities, manufacturers, and end users. The IEC

definition for this phenomenon is dip. The two terms are considered interchangeable, with

sag being the preferred synonym in the U.S. power quality community. Terminology used

to describe the magnitude of a voltage sag is often confusing. A“20 percent sag” can refer


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to a sag which results in a voltage of 0.8 or 0.2 p.u.. The preferred terminology would be

one that leaves no doubt as to the resulting voltage level: “a sag to 0.8 p.u.” or “a sag

whose magnitude was 20 percent.” When not specified otherwise, a 20 percent sag will

be considered an event during which the rms voltage decreased by 20 percent to 0.8 p.u..

The nominal, or base, voltage level should also be specified.

Figure 61 : Voltage DipsA swell is defined as an increase to between 1.1 and 1.8 p.u. in rms voltage or current at

the power frequency for durations from 0.5 cycle to 1 min. As with sags, swells are

usually associated with system fault conditions, but they are not as common as voltage

sags. One way that a swell can occur is from the temporary voltage rise on the unfaulted

phases during a Single-Line to Ground (SLG) fault. Figure 62 illustrates a voltage swell

caused by an SLG fault. Swells can also be caused by switching off a large load or

energizing a large capacitor bank. Swells are characterized by their magnitude (rms value)

and duration. The severity of a voltage swell during a fault condition is a function of the

fault location, system impedance, and grounding. On an ungrounded system, with an

infinite zero-sequence impedance, the line-to-ground voltages on the ungrounded phaseswill be 1.73 p.u. during an SLG fault condition. Close to the substation on a grounded

system, there will be little or no voltage rise on the unfaulted phases because the

substation transformer is usually connected delta-wye, providing a low-impedance

zero-sequence path for the fault current. Faults at different points along four-wire, multi

grounded feeders will have varying degrees of voltage swells on the unfaulted phases. A

15 percent swell, like that shown in figure 62, is common on U.S. utility feeders. The

term momentary overvoltage is used by many writers as a synonym for the term swell.


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Figure 62 : Voltage Swells

5.2 Harmonics

Harmonics are sinusoidal voltages or currents having frequencies that are integer

multiples of the frequency at which the supply system is designed to operate (termed the

fundamental frequency; usually 50 or 60 Hz). Periodically distorted waveforms can be

decomposed into a sum of the fundamental frequency and the harmonics. Harmonic

distortion originates in the nonlinear characteristics of devices and loads on the power

system. Harmonic distortion levels are described by the complete harmonic spectrum

with magnitudes and phase angles of each individual harmonic component. It is also

common to use a single quantity, the total harmonic distortion (THD), as a measure of the

effective value of harmonic distortion. Figure 63 illustrates the waveform and harmonicspectrum for a typical adjustable-speed-drive (ASD) input current. Current distortion

levels can be characterized by a THD value, as previously described, but this can often be

misleading. For example, many adjustable-speed drives will exhibit high THD values for

the input current when they are operating at very light loads. This is not necessarily a

significant concern because the magnitude of harmonic current is low, even though its

relative distortion is high. To handle this concern for characterizing harmonic currents in

a consistent fashion, IEEE Standard 519-1992 defines another term, the total demand

distortion (TDD). This term is the same as the total harmonic distortion except that the

distortion is expressed as a percent of some rated load current rather than as a percent of

the fundamental current magnitude at the instant of measurement. IEEE Standard

519-1992 provides guidelines for harmonic current and voltage distortion levels on

distribution and transmission circuits.


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Figure 63 : Current waveform and harmonic spectrum for an ASD input current.

5.3 Flicker

Voltage fluctuations are systematic variations of the voltage envelope or a series of

random voltage changes, the magnitude of which does not normally exceed the voltage

ranges specified by American National Standard Institute (ANSI) C84.1 of 0.9 to 1.1 p.u.

IEC 61000-2-1 defines various types of voltage fluctuations. We will restrict our

discussion here to IEC 61000-2-1 Type (d) voltage fluctuations, which are characterized

as a series of random or continuous voltage fluctuations. Loads that can exhibit

continuous, rapid variations in the load current magnitude can cause voltage variations

that are often referred to as flicker. The term flicker is derived from the impact of the

voltage fluctuation on lamps such that they are perceived by the human eye to flicker. To

be technically correct, voltage fluctuation is an electromagnetic phenomenon while

flicker is an undesirable result of the voltage fluctuation in some loads. However, the two

terms are often linked together in standards. Therefore, we will also use the common term

voltage flicker to describe such voltage fluctuations. An example of a voltage waveformwhich produces flicker is shown in figure 64. This is caused by an arc furnace, one of the

most common causes of voltage fluctuations on utility transmission and distribution

systems. The flicker signal is defined by its rms magnitude expressed as a percent of the

fundamental. Voltage flicker is measured with respect to the sensitivity of the human eye.

Typically, magnitudes as low as 0.5 percent can result in perceptible lamp flicker if the

frequencies are in the range of 6 to 8 Hz. IEC 61000-4-15 defines the methodology and


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specifications of instrumentation for measuring flicker. The IEEE Voltage Flicker

Working Group has recently agreed to adopt this standard as amended for 60Hz power

systems for use in North America. This standard devises a simple means of describing the

potential for visible light flicker through voltage measurements. The measurement

method simulates the lamp/eye/brain transfer function and produces a fundamental metric

called short-term flicker sensation (Pst). This value is normalized to 1.0 to represent thelevel of voltage fluctuations sufficient to cause noticeable flicker to 50 percent of a

sample observing group. Another measure called long-term flicker sensation (Plt) is often

used for the purpose of verifying compliance with compatibility levels established by

standards bodies and used in utility power contracts. This value is a longer-term average

of Pst samples.

Figure 64 : Flicker

5.4 Transients

The term transients has long been used in the analysis of power system variations to

denote an event that is undesirable and momentary in nature. The notion of a damped

oscillatory transient due to an RLC network is probably what most power engineers think

of when they hear the word transient. Other definitions in common use are broad in scope

and simply state that a transient is “that part of the change in a variable that disappears

during transition from one steady state operating condition to another.” Unfortunately,

this definition could be used to describe just about anything unusual that happens on the

power system. A utility engineer may think of a surge as the transient resulting from a

lightning stroke for which a surge arrester is used for protection. End users frequently use

the word indiscriminantly to describe anything unusual that might be observed on the

power supply ranging from sags to swells to interruptions. Because there are many

potential ambiguities with this word in the power quality field, we will generally avoid

using it unless we have specifically defined what it refers to. Transients can be classified

into two categories, impulsive and oscillatory.


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Figure 65 : Transients

6.0 CONCLUSION

Evolution of technology has create a lot of digital and graphical measuring devices in

order to obtain and observe a data/result in a detail and efficient ways. Before digital and

graphical device is used, analog device was a very important devices to be used in power

system measurement. Nowadays, analog measuring devices was replaces by the digital

and graphical measuring devices such as multimeter, oscilloscope, fluke clamp meter,

insulation meter and many other devices. In this experiment, we are using fluke clamp

meter to measure the voltage, current and frequency then observing the waveform trends

of the power quality problem. The Fluke 434 power quality analyzers can locate, predict,

prevent and troubleshoot problems in three- and single-phase power distribution systems.Troubleshooting is faster with on-screen display of trends and captured events, even

while background recording continues. The new IEC standards for flicker, harmonics and

power quality are built right in to take the guess work out of power quality.


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Figure 66 : Summary of power quality problem


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7.0 REFERENCES

Roger C. Dugan, Mark F. McGranaghan, Surya Santoso, H. Wayne Beaty. Electrical

Power System Quality. 2nd Edition.

M. A. Hannan. 2016. Introduction to Power Quality. Lecture Slide.

http://www.testequip.com/sale/details/HTS0174.html

http://ecmweb.com/power-quality-archive/power-quality-standards-industry-update

http://electrical-engineering-portal.com/9-most-common-power-quality-problems

http://www.power-solutions.com/power-quality

http://www.fluke.com/fluke/caen/community/fluke-news-plus/articlecategories/clamps/ac

-dc-clamp-meter

https://www.quora.com/How-does-a-change-in-AC-frequency-affect-an-electrical-system

http://www.powerstandards.com/tutorials/sagsandswells.php

http://www.myronzucker.com/Asset/PDF-and-Excel-Charts/IEEE-519-Tables.html
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