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
Current Stage
PPUB - Publication issued
Completion Date
10-Nov-2021
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IEC TR 63396
Edition 1.0 2021-11
TECHNICAL
REPORT
Noise measurement method on power capacitors
IEC TR 63396:2021-11(en)
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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

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 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

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IEC TR 63396:2021 © IEC 2021 – 3 –

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

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– 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

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

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.
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IEC TR 63396:2021 © IEC 2021 – 5 –

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.
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– 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.
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IEC TR 63396:2021 © IEC 2021 – 7 –
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]
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– 8 – IEC TR 63396:2021 © IEC 2021
3.2
sound pressure
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

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;
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).

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

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

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

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
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IEC TR 63396:2021 © IEC 2021 – 9 –

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

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

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

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

the noise source under test (ST) in operation, in decibels;
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– 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
...

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