Industry-Building
Power quality monitoring described in IEEE 1159
Electrical Distribution
Solutions
IEEE 1159 terminology
The phenomena in table 1 represent conducted
disturbances and do not include anomalies like
electromagnetic fields or radio frequency
interference. The first three categories are
generally considered intermittent phenomena;
while the last four (imbalance, distortion,
fluctuations and frequency variations) are
steady state or continuous disturbances. Some
specific issues of importance are summarized
below.
Voltage Sags and Swells
Voltage sag describes a decrease in effective
voltage for up to one minute in duration. The
corresponding European term is dip, and either
is considered acceptable by IEEE 1159. Voltage
sags are a type of short duration voltage
variation which is sometimes difficult to
distinguish from an interruption, during which
effective voltage drops to zero for a brief time.
Some sensitive machines in a facility are
affected (shut down) by voltage sags or the
more severe interruptions. Voltage sags are
usually far less costly to solve than interruptions,
so it is important to monitor power circuits with
equipment capable of capturing waveform
information.
The condition of an increase in effective voltage
is called a swell. This increase is sometimes
referred to as a surge, but, as the next section
When
you say…
You probably
mean…
blackout
sustained interruption
brownout
undervoltage
dirty power
electromagnetic phenomena
glitch
transient
outage
sustained interruption
spike
transient
surge
swell
blink
sag
describes, surge relates to a shorter-duration
event and is incorrectly used as a synonym for
swell. The opposite of sag is swell, not surge.
Power quality monitoring
described in IEEE 1159
Transients
Though IEEE 1159 was successfully balloted,
there is still some discussion in the power
quality community about the terms transient
and surge. IEEE 1159 states that the preferred
term to describe a sudden change in the steady
state condition of voltage or current is transient.
It points out, however, that surge is a
synonymous term since the IEEE Dictionary
uses the word transient to define surge.
Other parts of the IEEE community are involved
in the discussions about surge and transient.
The committee associated with IEEE Standard
C62 deals with surge protective devices,
although the term transient voltage surge
suppression is being phased out.
Introduction
In this issue
we introduce
a new IEEE
standard,
IEEE 1159.
Merging IEEE
and IEC
terms,
IEEE 1159
seeks to
standardize
many of
the terms
that we use
to describe
electrical
phenomena,
and to
recommend
ways
to measure
and interpret
these
phenomena
Brownout Versus Undervoltage
Another favorite term is brownout. Brownout
has been used extensively to describe
sustained periods of low voltage sometimes
initiated by a utility as a specific dispatch
strategy to reduce power delivery.
In IEEE 1159, undervoltage is the scientific
term which describes a brownout.
Undervoltage is specified as a decrease
in effective voltage to less than 90% for greater
than one minute. Brownout has been relegated
to the group of words whose use is
discouraged.
ENMED199036EN
Seven Phenomena Identified
Figure 3: IEEE 1159 attempts to define electromagnetic
phenomena which cause power quality problems.
The standard summarizes the experience of power quality
engineers from industry, manufacturing, utilities, universities,
national standards, and consulting.
Schneider Electric
Industries SA
Centre Merlin Gerin
F - 38050 Grenoble cedex
France
Tel.: +33 (0)4 76 57 60 60
Fax: +33 (0)4 76 57 73 62
http://www.schneiderelectric.com
service-commc4@mail.schneider.fr
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
This paper was originally published as a part of the series PowerLogic
Solutions, copyright Square D Company 1998. Used with permission.
This document has been
printed on ecological paper.
Published by: Schneider Electric SA
Design and layout by: Insign’
Printed by: Imprimerie des Deux-Ponts
11/1999
In producing the table, IEEE members attempted
to merge terminology from the United States and
European communities.
The International Electrotechnical Commission
(IEC) is the European equivalent of the IEEE
organization. Table 1 terminology represents the
influence of both organizations. The IEEE 1159
committee recognized the importance of moving
toward common terminology in the international
community.
The Recommended Practice also summarizes
the power quality monitoring experience of the
engineers who served on the IEEE 1159 working
group. It offers suggestions for monitoring, data
collection and interpretation, and provides an
extensive bibliography on power quality
references.
Category
Types
Typical Duration
Common Causes
Transients
Oscillatory, Impulsive
Less than 1 cycle
Lightning, Switching Loads
Short Duration
Variations
Sags, Swells,
Interruptions
Less than 1 minute
Faults, Motor Starting,
Utility Protective Equipment
Long Duration
Variations
Undervoltages,
Overvoltages,
Sustained
Interruptions
Voltage Imbalance
—
Steady State
Unbalanced Loads,
Equipment Failure
Waveform Distortion
Harmonics,
Notching, Noise
Steady State
Electronic Loads
Voltage Fluctuations
—
Steady State
Arcing Loads,
Loose Connections
Power Frequency
Variations
—
Steady State
Poor Generator Control
Table 1: Summary of IEEE 1159 terms
ENMED199036EN
ART.28269
A new power quality standard, Recommended
Practice for Monitoring Electric Power Quality,
was recently approved by the Institute of
Electrical and Electronics Engineers (IEEE).
IEEE standard 1159-1995:
c Defines electromagnetic phenomena which
can cause power quality
problems, and
c Recommends methods to measure and record
those phenomena.
Aristotle said that many disputes could be
deflated into a single paragraph if the disputants
dared to define their terms. IEEE 1159 attempts
to clearly define the electromagnetic phenomena
which can cause power quality problems.
This effort alone justifies reading the document.
All too often, engineers are met with a multitude
of words which attempt to describe power quality
aberrations. Spike, glitch, blink, outage, flicker,
and bump are all terms people use to describe
problems—and all are considered undefined
by IEEE 1159. In their place, the IEEE committee
recommends the terminology summarized
in table 1.
Over 1 minute
Poor Voltage Regulation,
Incorrect Transformer Tap Setting,
Overloaded Feeder,
Utility Equipment
Power quality monitoring described in IEEE 1159
Conclusion
Applications
IEEE 1159 summarizes years of
power quality monitoring
experience. Some electromagnetic
events are difficult to measure, yet
the solution to a baffling problem
can become clear if monitoring is
successful. The document presents
recommendations which can
assure that troublesome
phenomena are captured
for analysis.
Monitor Selection and Setup
Disturbance Reports
Successful measurement of electro-magnetic
phenomena starts with the proper monitoring
tool. The monitor must be capable of measuring
the voltage or current magnitudes likely to be
causing equipment disruptions. Most monitoring
devices utilize electronic digital technology and
high-speed sampling rates. These characteristics
are necessary because events which last less
than one cycle, or 0.016 seconds, can disrupt
sensitive loads.
Disturbance reports are an important tool in
resolving power quality issues. Disturbance
analyzers can capture literally hundreds of
electromagnetic phenomena an hour. Most are
meaningless to electrical loads. It is imperative,
therefore, that someone is designated with the
task of logging equipment problems.
This equipment log can then be compared with
the electro-magnetic phenomena measured to
determine which phenomena may be causing
the equipment malfunctions.
Users should be encouraged to record as
much information as possible, but keep in mind
that the time just after an equipment
malfunction or plant shutdown is often chaotic.
It is sometimes helpful to provide the user with
copies of a disturbance log form that lists
sensitive equipment, and has space for
recording weather conditions (storm, windy,
clear day), production losses, and other useful
information.
The PowerLogic Circuit
Monitor model CM2350
serves as an ideal device to
collect and store on-board,
reliable power quality
information.
Power quality monitors also have a variety of
output reporting methods. Some print
disturbance information on paper, while others
store events on diskette, or in on-board memory.
Disturbance events recorded on diskette can be
copied and pasted into word processing or
graphic programs to facilitate report writing.
IEEE working group members filled a longstanding need for consistency among power
quality engineers, vendors, and customers by
writing IEEE 1159. The document defines power
quality terms, and describes techniques for
correct power quality monitoring.
Use of IEEE 1159 can further your
understanding of complex power quality
problems. Operation of sensitive electronic
equipment now in use can be dramatically
improved by identifying and correcting power
system anomalies.
IEEE 1159 is an important part of this worthwhile
goal.
In practice, it is difficult to determine the source
of the disturbance simply by selecting a
certain monitoring location, especially if the
metering location is temporary. The best method
is to permanently install meters at key locations
within your facility, connect them on a
communications network, and use software
which can interrogate all the devices and search
for out-of-tolerance alarms.
Some types of disturbances produce consistent
electromagnetic phenomena at each occurrence.
Voltage sags due to faults on a utility
transmission system typically last six cycles. This
is the normal fault sensing and clearing time for
transmission system circuit breakers. Distribution
system faults usually cause sags or interruptions
lasting up to one second or more.
Whatever the monitor type, it must be
programmed correctly. Most electro-magnetic
phenomena are recorded by exception; that is,
disturbances are recorded when pre-selected
thresholds are exceeded. Proper programming
assures that the phenomenon which causes a
shutdown also exceeds a programming
threshold.
PowerLogic System
Manager™ Software is an
excellent tool to graphically
view and print out
waveforms, logs, and other
valuable power quality
reports.
IEEE Standard 1159 was published in 1995,
but its working group members continue to
Monitor Placement
The analyzer needs to be connected to the
electrical distribution system at a point where the
offending phenomena can be measured. The
usual starting place is
the electric circuit
supplying the machine
being affected by
power quality
problems. Further, it is
useful to connect the
monitor in the same
configuration as the
affected load, phaseto-phase for threephase three-wire loads,
for example.
target important monitoring issues. Three task
forces have been formed to write standards on
power quality instrumentation, data
interpretation, and data exchange. Their work
can be reviewed on IEEE’s website:
http://grouper.ieee.org/groups.
Larry Ray manager the Power Quality
and Energy Management consulting services
Another popular
monitoring location is
the service entrance.
This location is
sometimes selected
because the user
wants to know whether
the electromagnetic
phenomena are
generated internal to
the building, or on the
supplying utility system.
Figure 1: Voltage sags or dips are defined as decreases in effective voltage which last less than one minute. Waveform capture
monitoring is essential to distinguishing this phenomena from a momentary interruption which may cost much more to solve.
group in Schneider Electric’s North American
Division, served as technical editor and chair
of Std 1159, and now serves as chair of the
IEEE standards Coordinating Committee on
Power Quality, SCC-22.
Figure 2: Typical monitoring locations on a low voltage circuit (IEEE 1159 Table 7-2).
PowerLogic circuit monitors can measure important power system information at each point.
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
Power quality monitoring described in IEEE 1159
Conclusion
Applications
IEEE 1159 summarizes years of
power quality monitoring
experience. Some electromagnetic
events are difficult to measure, yet
the solution to a baffling problem
can become clear if monitoring is
successful. The document presents
recommendations which can
assure that troublesome
phenomena are captured
for analysis.
Monitor Selection and Setup
Disturbance Reports
Successful measurement of electro-magnetic
phenomena starts with the proper monitoring
tool. The monitor must be capable of measuring
the voltage or current magnitudes likely to be
causing equipment disruptions. Most monitoring
devices utilize electronic digital technology and
high-speed sampling rates. These characteristics
are necessary because events which last less
than one cycle, or 0.016 seconds, can disrupt
sensitive loads.
Disturbance reports are an important tool in
resolving power quality issues. Disturbance
analyzers can capture literally hundreds of
electromagnetic phenomena an hour. Most are
meaningless to electrical loads. It is imperative,
therefore, that someone is designated with the
task of logging equipment problems.
This equipment log can then be compared with
the electro-magnetic phenomena measured to
determine which phenomena may be causing
the equipment malfunctions.
Users should be encouraged to record as
much information as possible, but keep in mind
that the time just after an equipment
malfunction or plant shutdown is often chaotic.
It is sometimes helpful to provide the user with
copies of a disturbance log form that lists
sensitive equipment, and has space for
recording weather conditions (storm, windy,
clear day), production losses, and other useful
information.
The PowerLogic Circuit
Monitor model CM2350
serves as an ideal device to
collect and store on-board,
reliable power quality
information.
Power quality monitors also have a variety of
output reporting methods. Some print
disturbance information on paper, while others
store events on diskette, or in on-board memory.
Disturbance events recorded on diskette can be
copied and pasted into word processing or
graphic programs to facilitate report writing.
IEEE working group members filled a longstanding need for consistency among power
quality engineers, vendors, and customers by
writing IEEE 1159. The document defines power
quality terms, and describes techniques for
correct power quality monitoring.
Use of IEEE 1159 can further your
understanding of complex power quality
problems. Operation of sensitive electronic
equipment now in use can be dramatically
improved by identifying and correcting power
system anomalies.
IEEE 1159 is an important part of this worthwhile
goal.
In practice, it is difficult to determine the source
of the disturbance simply by selecting a
certain monitoring location, especially if the
metering location is temporary. The best method
is to permanently install meters at key locations
within your facility, connect them on a
communications network, and use software
which can interrogate all the devices and search
for out-of-tolerance alarms.
Some types of disturbances produce consistent
electromagnetic phenomena at each occurrence.
Voltage sags due to faults on a utility
transmission system typically last six cycles. This
is the normal fault sensing and clearing time for
transmission system circuit breakers. Distribution
system faults usually cause sags or interruptions
lasting up to one second or more.
Whatever the monitor type, it must be
programmed correctly. Most electro-magnetic
phenomena are recorded by exception; that is,
disturbances are recorded when pre-selected
thresholds are exceeded. Proper programming
assures that the phenomenon which causes a
shutdown also exceeds a programming
threshold.
PowerLogic System
Manager™ Software is an
excellent tool to graphically
view and print out
waveforms, logs, and other
valuable power quality
reports.
IEEE Standard 1159 was published in 1995,
but its working group members continue to
Monitor Placement
The analyzer needs to be connected to the
electrical distribution system at a point where the
offending phenomena can be measured. The
usual starting place is
the electric circuit
supplying the machine
being affected by
power quality
problems. Further, it is
useful to connect the
monitor in the same
configuration as the
affected load, phaseto-phase for threephase three-wire loads,
for example.
target important monitoring issues. Three task
forces have been formed to write standards on
power quality instrumentation, data
interpretation, and data exchange. Their work
can be reviewed on IEEE’s website:
http://grouper.ieee.org/groups.
Larry Ray manager the Power Quality
and Energy Management consulting services
Another popular
monitoring location is
the service entrance.
This location is
sometimes selected
because the user
wants to know whether
the electromagnetic
phenomena are
generated internal to
the building, or on the
supplying utility system.
Figure 1: Voltage sags or dips are defined as decreases in effective voltage which last less than one minute. Waveform capture
monitoring is essential to distinguishing this phenomena from a momentary interruption which may cost much more to solve.
group in Schneider Electric’s North American
Division, served as technical editor and chair
of Std 1159, and now serves as chair of the
IEEE standards Coordinating Committee on
Power Quality, SCC-22.
Figure 2: Typical monitoring locations on a low voltage circuit (IEEE 1159 Table 7-2).
PowerLogic circuit monitors can measure important power system information at each point.
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
Power quality monitoring described in IEEE 1159
Conclusion
Applications
IEEE 1159 summarizes years of
power quality monitoring
experience. Some electromagnetic
events are difficult to measure, yet
the solution to a baffling problem
can become clear if monitoring is
successful. The document presents
recommendations which can
assure that troublesome
phenomena are captured
for analysis.
Monitor Selection and Setup
Disturbance Reports
Successful measurement of electro-magnetic
phenomena starts with the proper monitoring
tool. The monitor must be capable of measuring
the voltage or current magnitudes likely to be
causing equipment disruptions. Most monitoring
devices utilize electronic digital technology and
high-speed sampling rates. These characteristics
are necessary because events which last less
than one cycle, or 0.016 seconds, can disrupt
sensitive loads.
Disturbance reports are an important tool in
resolving power quality issues. Disturbance
analyzers can capture literally hundreds of
electromagnetic phenomena an hour. Most are
meaningless to electrical loads. It is imperative,
therefore, that someone is designated with the
task of logging equipment problems.
This equipment log can then be compared with
the electro-magnetic phenomena measured to
determine which phenomena may be causing
the equipment malfunctions.
Users should be encouraged to record as
much information as possible, but keep in mind
that the time just after an equipment
malfunction or plant shutdown is often chaotic.
It is sometimes helpful to provide the user with
copies of a disturbance log form that lists
sensitive equipment, and has space for
recording weather conditions (storm, windy,
clear day), production losses, and other useful
information.
The PowerLogic Circuit
Monitor model CM2350
serves as an ideal device to
collect and store on-board,
reliable power quality
information.
Power quality monitors also have a variety of
output reporting methods. Some print
disturbance information on paper, while others
store events on diskette, or in on-board memory.
Disturbance events recorded on diskette can be
copied and pasted into word processing or
graphic programs to facilitate report writing.
IEEE working group members filled a longstanding need for consistency among power
quality engineers, vendors, and customers by
writing IEEE 1159. The document defines power
quality terms, and describes techniques for
correct power quality monitoring.
Use of IEEE 1159 can further your
understanding of complex power quality
problems. Operation of sensitive electronic
equipment now in use can be dramatically
improved by identifying and correcting power
system anomalies.
IEEE 1159 is an important part of this worthwhile
goal.
In practice, it is difficult to determine the source
of the disturbance simply by selecting a
certain monitoring location, especially if the
metering location is temporary. The best method
is to permanently install meters at key locations
within your facility, connect them on a
communications network, and use software
which can interrogate all the devices and search
for out-of-tolerance alarms.
Some types of disturbances produce consistent
electromagnetic phenomena at each occurrence.
Voltage sags due to faults on a utility
transmission system typically last six cycles. This
is the normal fault sensing and clearing time for
transmission system circuit breakers. Distribution
system faults usually cause sags or interruptions
lasting up to one second or more.
Whatever the monitor type, it must be
programmed correctly. Most electro-magnetic
phenomena are recorded by exception; that is,
disturbances are recorded when pre-selected
thresholds are exceeded. Proper programming
assures that the phenomenon which causes a
shutdown also exceeds a programming
threshold.
PowerLogic System
Manager™ Software is an
excellent tool to graphically
view and print out
waveforms, logs, and other
valuable power quality
reports.
IEEE Standard 1159 was published in 1995,
but its working group members continue to
Monitor Placement
The analyzer needs to be connected to the
electrical distribution system at a point where the
offending phenomena can be measured. The
usual starting place is
the electric circuit
supplying the machine
being affected by
power quality
problems. Further, it is
useful to connect the
monitor in the same
configuration as the
affected load, phaseto-phase for threephase three-wire loads,
for example.
target important monitoring issues. Three task
forces have been formed to write standards on
power quality instrumentation, data
interpretation, and data exchange. Their work
can be reviewed on IEEE’s website:
http://grouper.ieee.org/groups.
Larry Ray manager the Power Quality
and Energy Management consulting services
Another popular
monitoring location is
the service entrance.
This location is
sometimes selected
because the user
wants to know whether
the electromagnetic
phenomena are
generated internal to
the building, or on the
supplying utility system.
Figure 1: Voltage sags or dips are defined as decreases in effective voltage which last less than one minute. Waveform capture
monitoring is essential to distinguishing this phenomena from a momentary interruption which may cost much more to solve.
group in Schneider Electric’s North American
Division, served as technical editor and chair
of Std 1159, and now serves as chair of the
IEEE standards Coordinating Committee on
Power Quality, SCC-22.
Figure 2: Typical monitoring locations on a low voltage circuit (IEEE 1159 Table 7-2).
PowerLogic circuit monitors can measure important power system information at each point.
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
Industry-Building
Power quality monitoring described in IEEE 1159
Electrical Distribution
Solutions
IEEE 1159 terminology
The phenomena in table 1 represent conducted
disturbances and do not include anomalies like
electromagnetic fields or radio frequency
interference. The first three categories are
generally considered intermittent phenomena;
while the last four (imbalance, distortion,
fluctuations and frequency variations) are
steady state or continuous disturbances. Some
specific issues of importance are summarized
below.
Voltage Sags and Swells
Voltage sag describes a decrease in effective
voltage for up to one minute in duration. The
corresponding European term is dip, and either
is considered acceptable by IEEE 1159. Voltage
sags are a type of short duration voltage
variation which is sometimes difficult to
distinguish from an interruption, during which
effective voltage drops to zero for a brief time.
Some sensitive machines in a facility are
affected (shut down) by voltage sags or the
more severe interruptions. Voltage sags are
usually far less costly to solve than interruptions,
so it is important to monitor power circuits with
equipment capable of capturing waveform
information.
The condition of an increase in effective voltage
is called a swell. This increase is sometimes
referred to as a surge, but, as the next section
When
you say…
You probably
mean…
blackout
sustained interruption
brownout
undervoltage
dirty power
electromagnetic phenomena
glitch
transient
outage
sustained interruption
spike
transient
surge
swell
blink
sag
describes, surge relates to a shorter-duration
event and is incorrectly used as a synonym for
swell. The opposite of sag is swell, not surge.
Power quality monitoring
described in IEEE 1159
Transients
Though IEEE 1159 was successfully balloted,
there is still some discussion in the power
quality community about the terms transient
and surge. IEEE 1159 states that the preferred
term to describe a sudden change in the steady
state condition of voltage or current is transient.
It points out, however, that surge is a
synonymous term since the IEEE Dictionary
uses the word transient to define surge.
Other parts of the IEEE community are involved
in the discussions about surge and transient.
The committee associated with IEEE Standard
C62 deals with surge protective devices,
although the term transient voltage surge
suppression is being phased out.
Introduction
In this issue
we introduce
a new IEEE
standard,
IEEE 1159.
Merging IEEE
and IEC
terms,
IEEE 1159
seeks to
standardize
many of
the terms
that we use
to describe
electrical
phenomena,
and to
recommend
ways
to measure
and interpret
these
phenomena
Brownout Versus Undervoltage
Another favorite term is brownout. Brownout
has been used extensively to describe
sustained periods of low voltage sometimes
initiated by a utility as a specific dispatch
strategy to reduce power delivery.
In IEEE 1159, undervoltage is the scientific
term which describes a brownout.
Undervoltage is specified as a decrease
in effective voltage to less than 90% for greater
than one minute. Brownout has been relegated
to the group of words whose use is
discouraged.
ENMED199036EN
Seven Phenomena Identified
Figure 3: IEEE 1159 attempts to define electromagnetic
phenomena which cause power quality problems.
The standard summarizes the experience of power quality
engineers from industry, manufacturing, utilities, universities,
national standards, and consulting.
Schneider Electric
Industries SA
Centre Merlin Gerin
F - 38050 Grenoble cedex
France
Tel.: +33 (0)4 76 57 60 60
Fax: +33 (0)4 76 57 73 62
http://www.schneiderelectric.com
service-commc4@mail.schneider.fr
ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
This paper was originally published as a part of the series PowerLogic
Solutions, copyright Square D Company 1998. Used with permission.
This document has been
printed on ecological paper.
Published by: Schneider Electric SA
Design and layout by: Insign’
Printed by: Imprimerie des Deux-Ponts
11/1999
In producing the table, IEEE members attempted
to merge terminology from the United States and
European communities.
The International Electrotechnical Commission
(IEC) is the European equivalent of the IEEE
organization. Table 1 terminology represents the
influence of both organizations. The IEEE 1159
committee recognized the importance of moving
toward common terminology in the international
community.
The Recommended Practice also summarizes
the power quality monitoring experience of the
engineers who served on the IEEE 1159 working
group. It offers suggestions for monitoring, data
collection and interpretation, and provides an
extensive bibliography on power quality
references.
Category
Types
Typical Duration
Common Causes
Transients
Oscillatory, Impulsive
Less than 1 cycle
Lightning, Switching Loads
Short Duration
Variations
Sags, Swells,
Interruptions
Less than 1 minute
Faults, Motor Starting,
Utility Protective Equipment
Long Duration
Variations
Undervoltages,
Overvoltages,
Sustained
Interruptions
Voltage Imbalance
—
Steady State
Unbalanced Loads,
Equipment Failure
Waveform Distortion
Harmonics,
Notching, Noise
Steady State
Electronic Loads
Voltage Fluctuations
—
Steady State
Arcing Loads,
Loose Connections
Power Frequency
Variations
—
Steady State
Poor Generator Control
Table 1: Summary of IEEE 1159 terms
ENMED199036EN
ART.28269
A new power quality standard, Recommended
Practice for Monitoring Electric Power Quality,
was recently approved by the Institute of
Electrical and Electronics Engineers (IEEE).
IEEE standard 1159-1995:
c Defines electromagnetic phenomena which
can cause power quality
problems, and
c Recommends methods to measure and record
those phenomena.
Aristotle said that many disputes could be
deflated into a single paragraph if the disputants
dared to define their terms. IEEE 1159 attempts
to clearly define the electromagnetic phenomena
which can cause power quality problems.
This effort alone justifies reading the document.
All too often, engineers are met with a multitude
of words which attempt to describe power quality
aberrations. Spike, glitch, blink, outage, flicker,
and bump are all terms people use to describe
problems—and all are considered undefined
by IEEE 1159. In their place, the IEEE committee
recommends the terminology summarized
in table 1.
Over 1 minute
Poor Voltage Regulation,
Incorrect Transformer Tap Setting,
Overloaded Feeder,
Utility Equipment
Industry-Building
Power quality monitoring described in IEEE 1159
Electrical Distribution
Solutions
IEEE 1159 terminology
The phenomena in table 1 represent conducted
disturbances and do not include anomalies like
electromagnetic fields or radio frequency
interference. The first three categories are
generally considered intermittent phenomena;
while the last four (imbalance, distortion,
fluctuations and frequency variations) are
steady state or continuous disturbances. Some
specific issues of importance are summarized
below.
Voltage Sags and Swells
Voltage sag describes a decrease in effective
voltage for up to one minute in duration. The
corresponding European term is dip, and either
is considered acceptable by IEEE 1159. Voltage
sags are a type of short duration voltage
variation which is sometimes difficult to
distinguish from an interruption, during which
effective voltage drops to zero for a brief time.
Some sensitive machines in a facility are
affected (shut down) by voltage sags or the
more severe interruptions. Voltage sags are
usually far less costly to solve than interruptions,
so it is important to monitor power circuits with
equipment capable of capturing waveform
information.
The condition of an increase in effective voltage
is called a swell. This increase is sometimes
referred to as a surge, but, as the next section
When
you say…
You probably
mean…
blackout
sustained interruption
brownout
undervoltage
dirty power
electromagnetic phenomena
glitch
transient
outage
sustained interruption
spike
transient
surge
swell
blink
sag
describes, surge relates to a shorter-duration
event and is incorrectly used as a synonym for
swell. The opposite of sag is swell, not surge.
Power quality monitoring
described in IEEE 1159
Transients
Though IEEE 1159 was successfully balloted,
there is still some discussion in the power
quality community about the terms transient
and surge. IEEE 1159 states that the preferred
term to describe a sudden change in the steady
state condition of voltage or current is transient.
It points out, however, that surge is a
synonymous term since the IEEE Dictionary
uses the word transient to define surge.
Other parts of the IEEE community are involved
in the discussions about surge and transient.
The committee associated with IEEE Standard
C62 deals with surge protective devices,
although the term transient voltage surge
suppression is being phased out.
Introduction
In this issue
we introduce
a new IEEE
standard,
IEEE 1159.
Merging IEEE
and IEC
terms,
IEEE 1159
seeks to
standardize
many of
the terms
that we use
to describe
electrical
phenomena,
and to
recommend
ways
to measure
and interpret
these
phenomena
Brownout Versus Undervoltage
Another favorite term is brownout. Brownout
has been used extensively to describe
sustained periods of low voltage sometimes
initiated by a utility as a specific dispatch
strategy to reduce power delivery.
In IEEE 1159, undervoltage is the scientific
term which describes a brownout.
Undervoltage is specified as a decrease
in effective voltage to less than 90% for greater
than one minute. Brownout has been relegated
to the group of words whose use is
discouraged.
ENMED199036EN
Seven Phenomena Identified
Figure 3: IEEE 1159 attempts to define electromagnetic
phenomena which cause power quality problems.
The standard summarizes the experience of power quality
engineers from industry, manufacturing, utilities, universities,
national standards, and consulting.
Schneider Electric
Industries SA
Centre Merlin Gerin
F - 38050 Grenoble cedex
France
Tel.: +33 (0)4 76 57 60 60
Fax: +33 (0)4 76 57 73 62
http://www.schneiderelectric.com
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ENMED199036EN
Electrical Distribution
Solutions
Industry-Building
This paper was originally published as a part of the series PowerLogic
Solutions, copyright Square D Company 1998. Used with permission.
This document has been
printed on ecological paper.
Published by: Schneider Electric SA
Design and layout by: Insign’
Printed by: Imprimerie des Deux-Ponts
11/1999
In producing the table, IEEE members attempted
to merge terminology from the United States and
European communities.
The International Electrotechnical Commission
(IEC) is the European equivalent of the IEEE
organization. Table 1 terminology represents the
influence of both organizations. The IEEE 1159
committee recognized the importance of moving
toward common terminology in the international
community.
The Recommended Practice also summarizes
the power quality monitoring experience of the
engineers who served on the IEEE 1159 working
group. It offers suggestions for monitoring, data
collection and interpretation, and provides an
extensive bibliography on power quality
references.
Category
Types
Typical Duration
Common Causes
Transients
Oscillatory, Impulsive
Less than 1 cycle
Lightning, Switching Loads
Short Duration
Variations
Sags, Swells,
Interruptions
Less than 1 minute
Faults, Motor Starting,
Utility Protective Equipment
Long Duration
Variations
Undervoltages,
Overvoltages,
Sustained
Interruptions
Voltage Imbalance
—
Steady State
Unbalanced Loads,
Equipment Failure
Waveform Distortion
Harmonics,
Notching, Noise
Steady State
Electronic Loads
Voltage Fluctuations
—
Steady State
Arcing Loads,
Loose Connections
Power Frequency
Variations
—
Steady State
Poor Generator Control
Table 1: Summary of IEEE 1159 terms
ENMED199036EN
ART.28269
A new power quality standard, Recommended
Practice for Monitoring Electric Power Quality,
was recently approved by the Institute of
Electrical and Electronics Engineers (IEEE).
IEEE standard 1159-1995:
c Defines electromagnetic phenomena which
can cause power quality
problems, and
c Recommends methods to measure and record
those phenomena.
Aristotle said that many disputes could be
deflated into a single paragraph if the disputants
dared to define their terms. IEEE 1159 attempts
to clearly define the electromagnetic phenomena
which can cause power quality problems.
This effort alone justifies reading the document.
All too often, engineers are met with a multitude
of words which attempt to describe power quality
aberrations. Spike, glitch, blink, outage, flicker,
and bump are all terms people use to describe
problems—and all are considered undefined
by IEEE 1159. In their place, the IEEE committee
recommends the terminology summarized
in table 1.
Over 1 minute
Poor Voltage Regulation,
Incorrect Transformer Tap Setting,
Overloaded Feeder,
Utility Equipment