A New IEC Standard 

on the Measurement of Power Quality Parameters

François Martzloff 

f.martzloff@ieee.org 

Reprinted from Proceedings, EMC Europe 2000 Symposium, Bruges 2000 

Significance 

Part 2 – Development of standards – Reality Checks 

Part 5 – Monitoring instruments 

A progress report on the development of an IEC standard describing the background of the 

difficulties created by non-standard definitions and algorithms for power quality disturbances and 

presenting the approach recommended by the appointed IEC Working Group. 

At the time this paper was presented, consensus had not yet been reached, and the final 

document is scheduled by IEC for publication in mid-2003.
A NEW IEC STANDARD ON THE MEASUREMENT 

OF POWER QUALITY PARAMETERS 

Franqois D. Martzloff 

National Institute of Standards and Technology t 

Gaithersburg MD 20899-8 1 13 USA 

Abstract - Following an initiative from the French and 

the U.S. National Committees, the IEC Technical 

Committee TC77 charged its Subcommittee 77A (LowFrequency Phenomena) with the development of a new 

standard on the measurement of power quality 

parameters. The objectives of this standard, as stated in 

its scope, are to facilitate - and hopefully ensure - 

obtaining reliable, repeatable, and comparable results of 

power quality parameters, regardless of the compliant 

instrument being used and regardless of its environmental 

conditions. The purpose of this paper is to broaden the 

consensus-building process, beyond the closely-knit TC77 

community, toward greater acceptance when the project 

reaches the final draft voting status. 

I. BACKGROUND AND EXPECTED BENEFITS 

The pioneering development of portable power quality 

monitors, with built-in graphics capability, in the mid1980s triggered intense interest among equipment users 

concerned with disruption of their operations allegedly 

caused by poor quality of their electric power supply. 

Concurrently, increasing dependency on sophisticated 

electronic controls made the issue even more pressing. 

The availability of these graphic reports, which became 

known as "signatures" spurred a new awareness of power 

quality issues [I]. This interest opened the market to 

other instrument manufacturers, each developing their 

own algorithms and software for the measurements of a 

variety of disturbances, not necessarily based 

(shared) definitions of these disturbances 

As a consequence of these independent developments, the 

resulting survey data have been generally difficult, if not 

impossible, to compare between two surveys conducted 

with different instruments. During the initial phases of a 

new technology development, open competition will 

generally be a strong and welcome factor to promote 

innovation, but the result can also become chaotic and 

counter-productive. A first attempt toward bringing 

compatibility in this new field was made by the Institute 

of Electrical and Electronics Engineers (IEEE) in 1987, 

chartering a working group for the development of a 

Recommended Practice, which culminated in 1995 with 

the publication of IEEE Std. 1159 [5]. 

II. WHAT IS POWER QUALITY ? 

Asking this question in the year 2000, and after all the 

work and papers published since the term was first used 

[6] might seem awkward. However, a brief review of 

what diverse individuals and organizations mean by 

"Power Quality" will provide some perspective on the 

underlying issues, and will show how useful the new IEC 

standard will be to bring about a shared understanding. 

In a landmark 1996 decision, the Committee of Action of 

the IEC approved a recommendation to undertake work 

on power quality issues as part of the scope of Technical 

Committee TC77 on Electromagnetic Compatibility 

(EMC). This decision, recommended by an Ad Hoc 

Group composed of power quality experts from ten 

countries, marks an expansion of the scope that will then 

reach beyond the purely technical issues generally 

addressed by the EMC community. 

The IEC Ad Hoc Group considered in 1996 three areas of 

contributions which an IEC Power Quality Group could 

make, complementing the work currently done by existing 

working groups or project teams of TC77: 

Bringing order to the present chaos of uncoordinated 

methods of monitoring power quality. 

Proposing a classification of power quality levels 

describing what end-users can expect. 

Building bridges among producers and users of 

electric power, and equipment manufacturers. 

Concerns surfaced that undertaking such work might 

ultimately result in the development and imposition of 

standards on the quality of "electricity as a productn and 

create an adversarial relationship. Fortunately, these 

concerns seem to have receded and a new working group 

was chartered in 1997 with the specific scope of defining 

measurement methods "for obtaining reliable, repeatable, 

and comparable results regardless of the compliant 

instrument being used and regardless of its environmental 

conditions." 

The first Committee Draft (CD) of the IEC document has 

been circulated in 1999 [7] and resulted in 230 comments 

from the National Committees. With the concurrence of 

the IEC Working Group, this paper presents a progress 

report, identifying major topics and unresolved issues. 

t Electricity Division, Electronics and Electrical En~ineering Laboratory Technology Administranon. US. De*~artment of Commerce 

Contributions from the National Institute of Standards and Technology are not subject to U.S. Copyright. 
Power quality and EMC share many concerns, to the point 

that each has at some time been described as being a 

subset of the other. In addition to this fundamental 

technical aspect, other issues permeate any discussion of 

power quality. It would be more accurate to draw a multidimension diagram with many overlaps. Also involved 

are the principals in the transactions, remedial actions, and 

political implications (see Figure 1). 

As further illustration of the different perceptions of the 

power quality concept, Table 1 shows a collection of 

definitions developed by various standards-writing groups 

and industry publications. Another illustration of the 

diversity is Table 2 which shows the terms used in 

French-speaking countries, in their own national version 

of French (French being one of the official languages of 

the IEC) with a literal translation into English. 

PQ Monitor ..'. 

Power quality issues involve overlapping stakeholders' interests or technical aspects in 

many domains. In this figure, four domains are represented as planes in an exploded 

view, showing how for each domain, developing a Power Quality (PQ) document will 

involve overlapping topics and draw upon the interests and expertise of the stakeholders. 

A successful development will integrate all topics in each domain, and consolidate all. 

domains into one entity. (Note how the artist has provided registration pegs on the 

planes so that the re-assembly will be a good fit !) 

-. Figure i - The many dimensions of power quaiity issues 
Table 1 - Evolution of the concept of Power Quality 

SOURCE 

Key "Diagnosing Power-Quality 

Related Computer Problems" [6] 

Clemmensen and Ferraro, 

"The Emerging Problem of 

Electric Power Quality" [8] 

EPRl Internal papers 

-- 

PClM Magazine [9] 

IEEE Std 1100-1992 

IEEE Recommended Practice 

for Powering and Grounding 

Sensitive Electronic Equipment 

IEEE Std 1 159-1 995 

IEEE Recommended Practice 

for Monitoring Electrical Power 

Quality 

IEEE Std 1250-1995 IEEE 

Guide for Service to Equipment 

Sensitive to Momentary Voltage 

Disturbances 

Eskom Handbook on Quality of 

Supply 

Report from Advisory Committee 

on Electromagnetic Compatibility 

to IEC Committee of Action, 

1996. 

IEEE Std 1100-1999 

IEEE Recommended Practice 

for Powering and Grounding 

Electronic Equipment 

IEC Working Group 77ANVG09 

IEC Working Group 77WG09 

IEC 60050,605-01 -05 

International Vocabulary (IEV) 

DEFINITION - Explicit or Implicit 

"In summary, the answer to 'the power quality question' will be found 

only through a study of power line disturbances. This study is the first 

step towards an accurate diagnosis of computer power problems." 

Converse of "Dirty Power", the term often used in the early eighties to 

describe a power line where disturbances occur. Thus, power quality 

is the absence of disturbances. 

power quality: applies to the power coming from the electric utility 

supply side. 

"quality power is the level it takes to satisfy my customers needs." 

power quality: The concept of powering and grounding sensitive 

electronic equipment in a manner that is suitable to the operation of 

that equipment. 

power quality: The concept of powering and grounding sensitive 

electronic equipment in a manner that is suitable to the operation of 

that equipment. 

NOTE - Within the industry, alternate definitions or interpretations of power 

quality have been used, reflecting different points of view. Therefore, this 

definition might not be exclusive, pending development of a broader consensus. 

Power Quality is a broadly used term that has been applied to voltage, 

service availability, and even harmonic content. Except for Clause 1, 

the guide has purposely avoided the use of this term. 

power quality: Quality of supply as it affects the delivery of power and 

therefore includes elements of voltage quality and measurement of the 

availability or continuity of supply. 

power quality: Set of parameters defining the properties of the power 

supply as delivered to the user in normal operating conditions in terms 

of continuity of supply and characteristics of voltage (symmetry, 

frequency, magnitude, waveform) 

Note 1: Power quality expresses the uset's satisfaction with the supply of 

electricity. Power quality is good if electricity supply is within statutory and any 

contractual limits, and there are no complaints from users, and vice-versa it is 

bad if the power supply is outside of limits and there are complaints from users. 

Note 2: Power quality depends not only on the supply but can be strongly 

affected by the user's selection of equipment and installation practices. 

power quality: The concept of powering and grounding electronic 

equipment in a manner that is suitable to the operation of that 

equipment and compatible with the premise wiring and other connected 

equipment. 

power quality: 'Under consideration" 

power quality: 

Proposal # 1: See quality of the supply (See IEV definition below) 

Proposal #2 A set of technical parameters that describes the 

compatibility between electricity supplied on a network and the loads 

connected to that network. 

quality of supply: An appraisal of the deviation of technical criteria 

outside a defined range (explicit or implicit) of the electricity supply 01 

of the aggregate of electricity suppliers within an electrical system. 
Table 2 -Power Quality names in French-speaking countries 

Country I French Term 

Canada 

France 

Literal English Translation 

I Be'gium I 1. 'Power Quality" 

2. Qualit6 de I'alimentation 

1. Qualite de I'onde 

1. Qualite de la tension 

2. Quali:k & la foi;iRi:i;ie 

3. Qualite de I'energie electrique 

I I 

1. No misgiving about using the English in a French phrase 

2. Quality of the (power) supply I 

Switzerland 1. Qualit6 de la fourniture 

2. Disponibilite de la fourniture $ 

1. Quality of the wave I 

1. Quality of the voltage t 

2. QiiaiiQ, of the aiipp& 

3. Quality of the electrical energy 

1. Quality of the supply 

2. Availability of the supply 1 I I I 

t Notwithstanding a current proposal within IEC terminology groups to change from "voltage" to 'tension". 

$ In the context of UNIPEDE considerations. 

1. Overview 

From its inception, the IEC document was envisioned as 

consisting of two parts. The first part will be a normative 

standard defining the various parameters of power quality 

disturbances. These definitions will be in words as well 

as in precise mathematical formulae. The second part will 

be in the form of informative annexes providing important 

guidance on why, where, when, and how any power 

quality monitoring should be performed. One important 

aspect which needs to be recognized and is expected to 

surface in the final document, will be to address the 

measurement of currents (for harmonics and surges), a 

parameter presently ignored in typical power quality 

standards which have a limited focus on the voUage 

characteristics [lo], [l 11, [12], [13]. 

Normative Part - The normative part of the document 

contains the following elements: 

0 The usual EC recitation of scope, reference 

documents, and definitions; 

0 Organization of the measurements (instrument classes, 

parameters to be measured); 

Environment (accuracy tests, operating range); 

Measurement methods: power frequency, magnitude 

of the voltage, voltage dips and swells, interruptions, 

voltage unbalance, and mains signaling voltage; 

0 Technical characteristics: Two classes of instruments 

are described, with corresponding specifications of the 

environment and accuracy limits of each. 

Some parameters are described in detail, others are 

referred to existing IEC standards, and some still at the 

"Under Consideration "stage. Referral is given to IEC 

standard 61000-4-15 for flicker, and to IEC standard 

61000-4-7 for voltage harmonics and interharmonics but 

with no mention of harmonic currents. Some stakeholders 

are still focusing exclusively on voltage characteristics. 

Left under consideration at this stage - but intended to be 

completed for the final project draft - several items still 

need consensus-buildmg: power-frequency overvoltages, 

transient overvoltages (and currents) and, of all things, a 

definitive definition of the term "Power Quality." 

Informufive Part -The informative part of the document 

centins t!e fn!!nuring e!ements: 

Measurements for contract applications; 

0 Trouble-shooting applications; 

Statistical surveys applications; 

0 Installation precautions; 

Transducers; 

0 Surge current vs. surge voltage; 

Bibliography. 

This informative part will provide guidance on performing 

the measurements according to the specific purpose of the 

monitoring: 

Validating contractual compliance requires excellent 

repeatability and accuracy - one of the prime 

incentives in undertaking the work. 

Troubleshooting can be considerably facilitated by 

securing the 'signatures" of disturbances. A signature 

may be difficult to describe in the quantitative terms 

used in contract language but is an extremely powerful 

tool for a diagnostic of a power quality problem. 

0 Surveys of power quality have been performed by 

many organizations, but comparisons have been 

difficult. The information and the recommendations 

provided on the subject in the corresponding annex 

should improve the situation for future surveys. 

Changing the emphasis of surge measurements from 

voltage to current will provide a more realistic and 

useful basis for the design and application of surgeprotective devices [14]. 
y(, py) 

10 minutes 

8 2 hours 

This aggregation process is then applied, depending on 

the needs, to the reporting of harmonics, interharmonics, 

unbalance and voltage magnitude. 

IV. SCHEDULE AND REMAINING WORK 

To obtain an early feedback from the IEC National 

Committees, the somewhat unusual decision was made to 

circulate as a CD a document that still contains several 

important items left "Under Consideration." In this 

manner, it is expected that the next circulation of the 

document will be simpler and more efficient, with the 

working group taking advantage of the hiatus associated 

with the usual circulation of the document, comments, and 

responding to comments for working diligently on those 

items left "under consideration." It is expected that by the 

iimc of preseiiiauon of -~s paper, a second version CD 

will be completed and would be summarized in the oral 

presentation. 

V. ACKNOWLEDGMENTS 

The IEC document described in this paper is the result of 

contributions from fifteen individual experts appointed by 

their National Committees, involving typically three 

meetings per year and substantial homework. 

The seminal IEEE Standard 1159-1995 involved the 

contributions of 38 volunteers over a period of 8 years, 

and the group now working on the update includes more 

than forty volunteers. 

tool," Proceedings, PQA'91 Conference, 1991. 

[4! Rergern~, R., Pcwer Qudirj! Measureiiieiii 

Protocol, Report CEA 220 D711, First Edition, 

Canadian Electricity Association, May 1996. 

[5] IEEE Std 1 159-1995 - Recommended Practice for 

Monitoring Electric Power Quality, June 1995. 

[6] Key, T.S., "Diagnosing Power Quality-Related 

Computer Problems," IEEE Transactions IA-15, 

No.4, 1979. 

[7] IEC 77A/301/CD - Electromagnetic Compatibility 

(EMC) -Part 4-30: Testing and measurement 

techniques - Power Quality Measurement Methods. 

[8] Clemmensen, J.M. and Ferraro, R.J., "The 

Emerging Problem of Electric Power Quality," 

Public Utilities Fortnightly, November 28, 1985. 

[9] Sullivan, G.O., Lead article, PCIM Magazine, 

December 1988 

[lo] EN 50160-1994 - Voltage characteristics of 

electricity supplied by public distribution systems. 

[11] ESKOM - ESKASAAJ3 - 1994 Standard for the 

measurement and interpretation of voltage 

distortion in electrical energy systems. 

[12] UNIPEDE - NORMCOMP 87 - Measurement 

Guide for voltage characteristics, May 1995. 

[I31 UNIPEDE - NORMCOMP 89 - Application 

Guide to the European Standard EN 50160, 

September 1994. 

[15] Martzloff, F.D., 'Surge Recordings that Make Sense: 

Shifting focus from voltage to current measurements," 

Proceedings, EMC Roma, 1996