CISPR TR 18-1:2010
(Main)Radio interference characteristics of overhead power lines and high-voltage equipment - Part 1: Description of phenomena
Radio interference characteristics of overhead power lines and high-voltage equipment - Part 1: Description of phenomena
CISPR 18-1:2010(E), which is a technical report, applies to radio noise from overhead power lines and high-voltage equipment which may cause interference to radio reception. The scope of this publication includes the causes, measurement and effects of radio interference, design aspects in relation to this interference, methods and examples for establishing limits and prediction of tolerable levels of interference from high voltage overhead power lines and associated equipment, to the reception of radio broadcast services. The frequency range covered is 0,15 MHz to 300 MHz. Radio frequency interference caused by the pantograph of overhead railway traction systems is not considered in this technical report. This second edition cancels and replaces the first edition published in 1982. It is a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- while the first edition of CISPR 18-1 only covered the direct distance D0 for the establishment of standard profiles for the lateral radio noise field emanating from HV overhead power lines,
- this second edition now also allows for use of the lateral distance y0 for these purposes. This way it allows for the establishment of standard profiles for the lateral radio noise field also from modern HV overhead power line constructions with tall suspension towers.
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Standards Content (Sample)
TR CISPR 18-1
®
Edition 2.0 2010-06
TECHNICAL
REPORT
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Radio interference characteristics of overhead power lines and high-voltage
equipment –
Part 1: Description of phenomena
TR CISPR 18-1:2010(E)
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TR CISPR 18-1
®
Edition 2.0 2010-06
TECHNICAL
REPORT
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Radio interference characteristics of overhead power lines and high-voltage
equipment –
Part 1: Description of phenomena
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 33.100.01 ISBN 978-2-88912-016-1
® Registered trademark of the International Electrotechnical Commission
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– 2 – TR CISPR 18-1 © IEC:2010(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
2 Normative references .8
3 Terms and definitions .8
4 Radio noise from power lines.9
4.1 General .9
4.2 Physical aspects of radio noise .9
4.2.1 Mechanism of formation of a noise field.9
4.2.2 Definition of noise.12
4.2.3 Influence of external parameters .12
4.3 Main characteristics of the noise field resulting from conductor corona.13
4.3.1 General .13
4.3.2 Frequency spectrum .13
4.3.3 Lateral profile .14
4.3.4 Statistical distribution with varying seasons and weather conditions .16
5 Effects of corona from conductors .17
5.1 Physical aspects of corona from conductors .17
5.1.1 General .17
5.1.2 Factors in corona generation .17
5.2 Methods of investigation of corona by cages and test lines.19
5.2.1 General .19
5.2.2 Test cages.19
5.2.3 Test lines.20
5.3 Methods of predetermination .20
5.3.1 General .20
5.3.2 Analytical methods .20
5.3.3 CIGRÉ method .21
5.4 Catalogue of standard profiles.21
5.4.1 General .21
5.4.2 Principle of catalogue presentation.21
6 Radio noise levels due to insulators, hardware and substation equipment
(excluding bad contacts).23
6.1 Physical aspects of radio noise sources .23
6.1.1 General .23
6.1.2 Radio noise due to corona discharges at hardware.23
6.1.3 Radio noise due to insulators .23
6.2 Correlation between radio noise voltage and the corresponding field strength
for distributed and individual sources .25
6.2.1 General .25
6.2.2 Semi-empirical approach and formula.25
6.2.3 Analytical methods .27
6.2.4 Example of application .28
6.3 Influence of ambient conditions .28
7 Sparking due to bad contacts .28
7.1 Physical aspects of the radio noise phenomenon .28
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TR CISPR 18-1 © IEC:2010(E) – 3 –
7.2 Example of gap sources .29
8 Special d.c. effects .30
8.1 General .30
8.2 Effects of corona from conductors .30
8.3 Radio noise due to insulators, hardware and substation equipment .34
8.4 Valve firing effects.34
9 Figures .36
Annex A (informative) Calculation of the voltage gradient at the surface of a conductor
of an overhead line .46
Annex B (informative) Catalogue of profiles of radio noise field due to conductor
corona for certain types of power line .50
Annex C (informative) Summary of the catalogue of radio noise profiles according to
the recommendations of the CISPR .66
Bibliography.68
Figure 1 – Typical lateral attenuation curves for high voltage lines, normalized to a
lateral distance of y = 15 m, distance in linear scale.36
0
Figure 2 – Typical lateral attenuation curves for high voltage lines, normalized to a
direct distance of D = 20 m, distance in logarithmic scale.37
0
Figure 3 – Examples of statistical yearly distributions of radio-noise levels recorded
continuously under various overhead lines.38
Figure 4 – Examples of statistical yearly distributions of radio-noise levels recorded
continuously under various overhead lines.39
Figure 5 – Example of statistical yearly distributions of radio-noise levels recorded
continuously under various overhead lines.40
Figure 6 – Examples of statistical yearly distributions of radio-noise levels recorded
continuously under various overhead lines.41
Figure 7 – Equipotential lines for clean and dry insulation units .42
Figure 8 – Determination of the magnetic field strength from a perpendicular to a
section of a line, at a distance x from the point of injection of noise current I .43
Figure 9 – Longitudinal noise attenuation versus distance from noise source (from test
results of various experiments frequencies around 0,5 MHz).43
Figure 10 – Lateral profile of the radio noise field strength produced by distributed
discrete sources on a 420 kV line of infinite length.44
Figure 11 – Example of relative strength of radio noise field as a function of frequency .45
Figure 12 – Example of relative strength of radio noise field as a function of the
distance from the line.45
Figure B.1 – Triangular formation (1) .51
Figure B.2 – Triangular formation (2) .52
Figure B.3 – Flat formation .53
Figure B.4 – Arched formation .54
Figure B.5 – Flat wide formation .55
Figure B.6 – Vertical formation (480 (Rail) X 4B) .56
Figure B.7 – Flat formation .57
Figure B.8 – Flat formation .58
Figure B.9 – Arched formation .59
Figure B.10 – Flat formation .60
Figure B.11 – Arched formation .61
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Figure B.12 – Flat formation .62
Figure B.13 – Vertical formation (480 (Cardinal) X 6B).63
Figure B.14 – Typical frequency spectra for the radio noise fields of high voltage
power lines .64
Figure B.15 – Prediction of radio noise level of a transmission line for various types of
weather .65
Figure C.1 – Examples of transformations of the profiles of Figures B.1 to B.13 using
the direct distance of 20 m as reference .67
Table B.1 – List of profiles .50
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TR CISPR 18-1 © IEC:2010(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
____________
RADIO INTERFERENCE CHARACTERISTICS
OF OVERHEAD POWER LINES
AND HIGH-VOLTAGE EQUIPMENT –
Part 1: Description of phenomena
FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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example "state of the art".
CISPR 18-1, which is a technical report, has been prepared by CISPR subcommittee B:
Interference relating to industrial, scientific and medical radio-frequency apparatus, to other
(heavy) industrial equipment, to overhead power lines, to high voltage equipment and to
electric traction.
This second edition cancels and replaces the first edition published in 1982. It is a technical
revision.
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– 6 – TR CISPR 18-1 © IEC:2010(E)
This edition includes the following significant technical changes with respect to the previous
edition: while the first edition of CISPR 18-1 only covered the direct distance D for the
0
establishment of standard profiles for the lateral radio noise field emanating from HV
overhead power lines, this second edition now also allows for use of the lateral distance y for
0
these purposes. This way it allows for the establishment of standard profiles for the lateral
radio noise field also from modern HV overhead power line constructions with tall suspension
towers.
The text of this technical report is based on the following documents:
DTR Report on voting
CISPR/B/493/DTR CISPR/B/501/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This technical report has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the CISPR 18 series can be found, under the general title Radio
interference characteristics of overhead power lines and high-voltage equipment, on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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TR CISPR 18-1 © IEC:2010(E) – 7 –
INTRODUCTION
This technical report forms the first of a three-part publication dealing with radio noise
generated by electrical power transmission and distribution facilities (overhead lines and
substations). It contains information in relation of the physical phenomena involved in the
generation of electromagnetic noise fields. It also includes the main properties of such fields
and their numerical values. Its content was adjusted such as to allow for use of the lateral
distance y for the establishment of standard profiles for the lateral radio noise field emanating
from HV overhead power lines.
The technical data given in this part 1 of the CISPR 18 series are intended to be a useful aid
to overhead line designers and also to anyone concerned with checking the radio noise
performance of a line to ensure satisfactory protection of wanted radio signals. The data
should facilitate the use of the recommendations given in its parts 2 and 3 dealing with
– methods of measurement and procedures for determining limits, and a
– code of practice for minimizing the generation of radio noise.
The CISPR 18 series do not deal with biological effects on living matter or any issues related
to exposure in electromagnetic fields.
This technical report has been prepared in order to provide information on the many factors
involved in protecting the reception of radio and television broadcasting from interference due
to high voltage overhead power lines and associated equipment. The information given should
be of assistance when means of avoiding or abating radio noise are being considered.
Information is mainly given on the generation and characteristics of radio noise from a.c.
power lines and equipment operating at 1 kV and above, in the frequency ranges 0,15 MHz to
30 MHz (a.m. sound broadcasting) and 30 MHz to 300 MHz (f.m. sound broadcasting and
television broadcasting). The special aspect of spark discharges due to bad contacts is taken
into account. Some information is also given on interference due to d.c. overhead lines for
which corona and interference conditions are different from those of a.c. power lines.
The general procedure for establishing the limits of the radio noise from the power lines and
equipment is given, together with typical values as examples, and methods of measurement.
The clause on limits concentrates on the low frequency and medium frequency bands as it is
only in these where ample evidence, based on established practice, is available. No examples
of limits to protect reception in the frequency band 30 MHz to 300 MHz have been given, as
measuring methods and certain other aspects of the problems in this band have not yet been
fully resolved. Site measurements and service experience have shown that levels of noise
from power lines at frequencies higher than 300 MHz are so low that interference is unlikely to
be caused to television reception.
The values of limits given as examples are calculated to provide a reasonable degree of
protection to the reception of broadcasting at the edges of the recognized service areas of the
appropriate transmitters in the a.m. radio frequency bands, in the least favourable conditions
likely to be generally encountered. These limits are intended to provide guidance at the
planning stage of the line and national standards or other specifications against which the
performance of the line may be checked after construction and during its useful life.
Recommendations are made on the design, routing, construction and maintenance of the lines
and equipment forming part of the power distribution system to minimize interference and it is
hoped that this publication will aid other radio services in the consideration of the problems of
interference.
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RADIO INTERFERENCE CHARACTERISTICS
OF OVERHEAD POWER LINES
AND HIGH-VOLTAGE EQUIPMENT –
Part 1: Description of phenomena
1 Scope
This part of CISPR 18, which is a technical report, applies to radio noise from overhead power
lines and high-voltage equipment which may cause interference to radio reception. The scope
of this publication includes the causes, measurement and effects of radio interference, design
aspects in relation to this interference, methods and examples for establishing limits and
prediction of tolerable levels of interference from high voltage overhead power lines and
associated equipment, to the reception of radio broadcast services.
The frequency range covered is 0,15 MHz to 300 MHz.
Radio frequency interference caused by the pantograph of overhead railway traction systems
is not considered in this technical report.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050-161, International Electrotechnical Vocabulary (IEV) – Chapter 161:
Electromagnetic compatibility
CISPR 16-1-1, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring
apparatus
CISPR/TR 18-2:2010, Radio interference characteristics of overhead power lines and
high-voltage equipment – Part 2: Methods of measurement and procedure for determining
limits
ISO/IEC Guide 99, International vocabulary of metrology – Basic and general concepts and
associated terms (VIM)
NOTE Informative references are listed in the Bibliography.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the IEC 60050-161 and
the ISO/IEC Guide 99 apply.
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TR CISPR 18-1 © IEC:2010(E) – 9 –
4 Radio noise from power lines
4.1 General
Radio noise from high voltage, which is to say above 1 kV, overhead power lines may be
generated over a wide band of frequencies by
a) corona discharges in the air at the surfaces of conductors, insulator assemblies and
hardware;
b) discharges and sparking at highly stressed areas of insulators;
c) sparking at loose or imperfect contacts of hardware.
The sources of a) and b) are usually distributed along the length of the line, but source c) is
usually local. For lines operating above about 100 kV, the electric stress in the air at the
surface of conductors and hardware can cause corona discharges. Sparking at bad contacts
or broken or cracked insulators can give rise to local sources of radio noise. High voltage
apparatus in substations may also generate radio noise which can be propagated along the
overhead lines.
If the field strength of the radio noise at the antennas used for receiving broadcast sound and
television services is too high, it can cause degradation of the sound output and, in the case
of television, the picture also.
The generation of radio noise is affected by weather conditions, for example, conductor
corona is more likely to occur in wet weather because of the water droplets which form on the
conductors whereas, under these conditions, bad contacts can become bridged with water
droplets and the generation of radio noise, by this process, ceases. Consequently, loose or
imperfect contacts are more likely to spark in dry weather conditions. Dry, clean insulators
may cause interference in fair weather, but prolonged sparking on the surfaces of insulators is
more likely to occur when they are polluted, particularly during wet, foggy or icy conditions.
For interference-free reception of radio and television signals it is important that a sufficiently
high ratio is available at the input to the receiver between the level of the wanted signal and
the level of the unwanted radio noise. Interference may therefore be experienced when the
signal strength is low and the weather conditions are conducive to the generation of radio
noise.
When investigating radio noise it should be borne in mind that the local field may be caused
by a distant source or sources as the noise may be propagated along the line over a
considerable distance.
4.2 Physical aspects of radio noise
4.2.1 Mechanism of formation of a noise field
4.2.1.1 General
Corona discharges on conductors, insulators or line hardware or sparking at bad contacts can
be the source of radio noise as they inject current pulses into the line conductors. These
propagate along the conductors in both directions from the injection point. The various
components of the frequency spectrum of these pulses have different effects.
In the frequency range 0,15 MHz to a few megahertz, the noise is largely the result of the
effect of propagation along the line. Direct electromagnetic radiation from the pulse sources
themselves does not materially contribute to the noise level. In this case the wavelength is
long in comparison with the clearances of the conductors and thus the line is not an efficient
radiator. Ho
...
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