IEC TR 63396:2021

Noise measurement method on power capacitors

IEC TR 63396:2021(E) documents a method for the sound pressure level measurement on power capacitor units, by which the sound power level of power capacitor units is determined.
This method is applicable to shunt capacitor units and AC filter capacitor units for AC power systems with a nominal voltage of 1 kV and above and a frequency of 50 Hz or 60 Hz.
This method also applies to the DC filter capacitor units.
Other measurements on power capacitor units can be implemented with reference to this method.

General Information

• Status: Published
• Publication Date: 09-Nov-2021
• ICS: 29.120.99 - Other electrical accessories
• ICS: 31.060.70 - Power capacitors
• Technical Committee: TC 33 - Power capacitors and their applications
• Current Stage: PPUB - Publication issued
• Start Date: 10-Nov-2021
• Completion Date: 13-Dec-2021

Overview - IEC TR 63396:2021 (Noise measurement method on power capacitors)

IEC TR 63396:2021 documents a standardized method to measure sound pressure levels on power capacitor units so that their sound power level can be determined. The technical report applies to shunt capacitor units, AC filter capacitor units for AC systems with nominal voltage of 1 kV and above (50 Hz or 60 Hz), and to DC filter capacitor units. It fills a gap for capacitor-specific acoustic testing (including use in HVDC converter stations) and provides a basis for consistent laboratory and field measurements.

Key topics and technical requirements

The report defines the measurement method and associated requirements, including:

• Power injection conditions: specified current/voltage injection scenarios for shunt, AC filter and DC filter capacitor units to simulate operating conditions.
• Measuring environment: recommended environment considerations for reliable sound pressure measurements.
• Acoustic instrument requirements: characteristics for basic sound level meters and filters referenced to IEC 61672-1 and IEC 61260-1.
• Reference box and measurement surface: definition of a reference parallelepiped enclosing the unit and the measurement surface where microphone positions are located.
• Microphone arrangement: guidance on positions and orientations for microphones to obtain spatial averages (Annex A).
• Calculation methods: procedures to calculate average sound pressure levels on the measurement surface and derive sound power level.
• Uncertainty assessment: measurement of uncertainty and test acceptance criteria (Table 1).
• Reporting: required test report content and typical report format (Annex C), plus example test circuits (Annex B).

Practical applications and users

IEC TR 63396:2021 is intended for:

• Test laboratories performing type tests and routine acoustic checks of power capacitors.
• Manufacturers seeking consistent methods to characterize acoustic emissions during R&D and production verification.
• Power utilities and EPCs evaluating capacitor noise for substation design, particularly for HVDC converter stations and filter banks.
• Acoustic consultants and regulatory bodies assessing environmental noise compliance and mitigation measures at substations.

Practical uses include product development, type approval, site acceptance testing, environmental impact assessment, and equipment selection where noise is a factor.

Related standards (normative references)

• IEC 61672-1:2013 - Sound level meters (specifications)
• IEC 61260-1:2014 - Octave-band and fractional-octave-band filters
• ISO 3744:2010 - Determination of sound power levels using sound pressure (engineering method)

Keywords: IEC TR 63396:2021, noise measurement, power capacitors, sound pressure level, sound power level, shunt capacitor, AC filter capacitor, DC filter, HVDC, microphone arrangement, measurement uncertainty.

Standards Content (Sample)

IEC TR 63396 ®
Edition 1.0 2021-11
TECHNICAL
REPORT
Noise measurement method on power capacitors
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IEC TR 63396 ®
Edition 1.0 2021-11
TECHNICAL
REPORT
Noise measurement method on power capacitors

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.99; 31.060.70 ISBN 978-2-8322-1049-8

– 2 – IEC TR 63396:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Noise measurement . 10
4.1 Power injection conditions for capacitors . 10
4.1.1 Current injection conditions for shunt capacitor units . 10
4.1.2 Current injection conditions for AC filter capacitor units . 11
4.1.3 Current and voltage injection conditions for DC filter capacitor units . 11
4.2 Measuring environment . 11
4.3 Characteristics for basic acoustic instruments . 11
4.4 Arrangement of the power capacitors . 11
4.5 Arrangement of the microphone . 12
4.6 Measurement on sound pressure levels . 12
4.6.1 General . 12
4.6.2 Calculation of average sound pressure level at measurement surface . 12
5 Measurement of uncertainty . 14
6 Test report . 15
Annex A (informative) Microphone arrangement on noise measurement surface of
power capacitors. 16
A.1 Measurement surface . 16
A.2 Measurement positions and orientation of microphone . 17
Annex B (informative) Typical test circuit for power capacitor noise measurement . 18
B.1 Shunt and AC filter power capacitor noise test circuit . 18
B.2 DC filter power capacitor noise test circuit . 18
Annex C (informative) Typical format of power capacitor noise test report . 19
C.1 Basic information in the typical test report . 19
C.2 Sound level meter parameters . 19
C.3 Test parameter configuration . 19
C.4 Noise measurement data . 20
C.5 Meteorological conditions of the test environment . 21
C.6 Measuring personnel and time . 21
Bibliography . 22

Figure A.1 – Schematic diagram of installation of the test object . 16
Figure A.2 – Microphone positions on the parallelepiped measurement surface . 17
Figure B.1 – Schematic diagram of shunt and AC filter power capacitor noise test
circuit. 18
Figure B.2 – Schematic diagram of DC filter power capacitor noise test circuit . 18

Table 1 – Test acceptance criteria . 13
Table A.1 – Coordinates of measurement positions on the parallelepiped measurement
surface . 17
Table C.1 – Power supply loaded to the test object . 20
Table C.2 – Background A-weighted sound pressure level of each measuring point in

decibels . 20
Table C.3 – A-weighted sound pressure level of each measuring point in decibels . 20

– 4 – IEC TR 63396:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NOISE MEASUREMENT METHOD ON POWER CAPACITORS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 63396 has been prepared by technical committee 33: Power capacitors and their
applications. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
33/658/DTR 33/663/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.

The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC TR 63396:2021 © IEC 2021
INTRODUCTION
Power capacitors are important equipment for HVDC project, but at the same time they are also
the main noise source. However, there is no IEC document which is specific to the noise
measurement on power capacitors until now.
In recent years, Chinese authoritative testing organizations have conducted a large number of
experiments in this area. Now, many laboratories in China are able to simulate the actual
operating conditions of power capacitors in HVDC converter stations for noise testing.
This new technical report is aimed to document a feasible method to measure power capacitor's
noise in AC and DC systems, in particular in HVDC converter stations, based on the experience
developed in China. Furthermore, the testing laboratories could also check and validate
periodically the common technical parameters of the noise measurement on power capacitors
in an uniform way by this method, in order to promote the practical application of the
measurement method and possibly to improve it (in view of a possible future conversion of the
technical report to a technical specification).
This document is intended to fill the gap in this technical field, and to promote the construction
of environmentally friendly AC and DC substations.

NOISE MEASUREMENT METHOD ON POWER CAPACITORS

1 Scope
The object of this Technical Report is to document a method for the sound pressure level
measurement on power capacitor units, by which the sound power level of power capacitor units
is determined.
This method is applicable to shunt capacitor units and AC filter capacitor units for AC power
systems with a nominal voltage of 1 kV and above and a frequency of 50 Hz or 60 Hz.
This method also applies to the DC filter capacitor units.
Other measurements on power capacitor units can be implemented with reference to this
method.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 61260-1:2014, Electroacoustics – Octave-band and fractional-octave-band filters – Part 1:
Specifications
IEC 61672-1:2013, Electroacoustics – Sound level meters – Part 1: Specifications
ISO 3744:2010, Acoustics – Determination of sound power levels and sound energy levels of
noise sources using sound pressure – Engineering methods for an essentially free field over a
reflecting plane
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
noise
unwanted sound
[SOURCE: IEC TS 61973:2012, 3.1.13]

– 8 – IEC TR 63396:2021 © IEC 2021
3.2
sound pressure
p
fluctuating pressure superimposed on the static pressure
Note 1 to entry: Sound pressure is expressed in pascals (Pa).
Note 2 to entry: Sound pressure is usually expressed through the use of a decibel scale, as sound pressure level.
[SOURCE: IEC TS 61973:2012, 3.1.3]
3.3
sound pressure level
L
p
logarithm of the ratio of the RMS value of a given sound pressure to the reference sound
pressure
𝑝𝑝 𝑝𝑝
𝐿𝐿 = 10log = 20log , (1)
𝑝𝑝
𝑝𝑝 𝑝𝑝
0 0
where:
p is the measured RMS sound pressure, in pascals;
–5
p is the reference RMS pressure of 2 × 10 Pa, which corresponds to the 0 dB as
threshold of audibility.
Note 1 to entry: log(x) means the logarithm with base 10 of x; this convention is used throughout this document.
Note 2 to entry: The sound pressure level (L ) is expressed in decibels (dB).
p
Note 3 to entry: Sound pressure level is measured with sound level meters, which normally incorporate a frequency-
weighting filter. For further details see 3.2.3 of IEC TS 61973:2012.
Note 4 to entry: Since the sound level distribution measured around sound emitting objects is usually non-uniform
it is normally necessary to assess sound levels on spatial average figures gained from several measuring positions
rather than on one single discrete position.
[SOURCE: IEC TS 61973:2012, 3.1.4]
3.4
sound power
P
through a surface, product of the sound pressure, p, and the component of the particle velocity,
u , at a point on the surface in the direction normal to the surface, integrated over that surface
n
Note 1 to entry: Sound power is expressed in watts.
Note 2 to entry: The quantity relates to the rate per time at which airborne sound energy is radiated by a source.
[SOURCE: ISO 3744:2010, 3.20]
3.5
sound power level
L
w
ten times the logarithm to the base 10 of the ratio of the sound power of a source, P, to a
reference value, P , expressed in decibels (dB)
𝑃𝑃
𝐿𝐿 = 10log (2)
𝑊𝑊
𝑃𝑃
where the reference value, P , is 1 pW
Note 1 to entry: If a specific weighting as specified in IEC 61672-1 and/or specific frequency bands are applied,
this is indicated by appropriate subscripts; e.g. L denotes the A-weighted sound power level.
W(A)
[SOURCE: ISO 3744:2010, 3.21]
3.6
reference box
hypothetical right parallelepiped terminating on the reflecting plane(s) on which the noise
source under test is located, that just encloses the source including all the significant sound
radiating components and any test table on which the source is mounted
Note 1 to entry: The test table as small as possible be used.
Note 2 to entry: Reference radiating plane of capacitor unit is the cuboid surface consisting of the six sides of the
capacitor unit enclosure only and excluding the wiring terminals.
[SOURCE: ISO 3744:2010, 3.10]
3.7
measurement surface
S
hypothetical surface of an area, S, on which the microphone positions are located at which the
sound pressure levels are measured, enveloping the noise source under test and terminating
on the reflecting plane(s) on which the source is located
[SOURCE: ISO 3744:2010, 3.14]
3.8
background noise
noise from all sources other than the noise source under test
Note 1 to entry: Background noise includes contributions from airborne sound, noise from structure-borne vibration,
and electrical noise in the instrumentation.
Note 2 to entry: The background noise considers noise from the associated power equipment which operates and
stops simultaneously with the capacitor unit.
[SOURCE: ISO 3744:2010, 3.15]
3.9
synthesis of sound pressure level
superposition of sound pressure levels generated by two or more sound sources at a certain
point in the sound field
3.10
directivity index
*
D
Ii
measure of the extent to which a noise source under test radiates sound in the direction of the
i microphone position on a measurement surface, relative to the mean sound radiation over
th
the measurement surface
∗
′
𝐷𝐷 =𝐿𝐿 −(𝐿𝐿 −𝐾𝐾 ) (3)
𝑝𝑝𝐼𝐼(𝑆𝑆𝑆𝑆) 1
𝐼𝐼𝐼𝐼 𝑝𝑝(𝑆𝑆𝑆𝑆)
where
𝐿𝐿 is the background noise-corrected time-averaged (or single event time-integrated)
𝑝𝑝𝐼𝐼(𝑆𝑆𝑆𝑆)
sound pressure level for the i microphone position on the measurement surface, with
th
the noise source under test (ST) in operation, in decibels;

– 10 – IEC TR 63396:2021 © IEC 2021
′
𝐿𝐿 is the mean (energy average) time-averaged (or single event time-integrated) sound
𝑝𝑝(𝑆𝑆𝑆𝑆)
pressure level over all the microphone positions on the measurement surface for noise
source under test, in decibels;
K is the background noise correction, in decibels.
[SOURCE: ISO 3744:2010, 3.24]
3.11
fundamental current
current with a frequency equal to the power frequency of the AC system connected with the
capacitor
3.12
harmonic current
current with a frequency that is a multiple of the power frequency of the AC system connected
with the capacitor
3.13
capacitor unit
assembly of one or more capacitor elements in the same container with terminals brought out
[SOURCE: IEC 60050-436:1990, 436-01-04]
3.14
shunt capacitor
power capacitor intended to be connected in parallel with a network
Note 1 to entry: These capacitors are used primarily for power factor correction by reactive power compensation.
[SOURCE: IEC 60050-436:1990, 436-02-02]
3.15
AC filter capacitor
power capacitor intended to form part of a circuit designed to reduce one or more harmonic
currents present in the AC network
3.16
DC filter capacitor
power capacitor used to suppress the harmonics of the DC network
4 Noise measurement
4.1 Power injection conditions for capacitors
4.1.1 Current injection conditions for shunt capacitor units
The max
...