SIST EN 60076-10:2002
(Main)Power transformers -- Part 10: Determination of sound levels
Power transformers -- Part 10: Determination of sound levels
Defines sound pressure and sound intensity measurement methods by which sound power levels of transformers, reactors and their associated cooling auxiliaries may be determined. The methods are applicable to transformers and reactors covered by the EN 60076 series, EN 60289, EN 60726 and the EN 61378 series, without limitation as regards size or voltage and when fitted with their normal cooling auxiliaries. This standard is primarily intended to apply to measurements made at the factory. Conditions on-site may be very different because of the proximity of objects, including other transformers. Nevertheless, the same general rules as are given in this standard may be followed when on-site measurements are made.
Leistungstransformatoren -- Teil 10: Bestimmung der Geräuschpegel
Transformateurs de puissance -- Partie 10: Détermination des niveaux de bruit
Disponible uniquement en anglais
Power transformers - Part 10: Determination of sound levels (IEC 60076-10:2001)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 60076-10:2002
01-oktober-2002
1DGRPHãþD
SIST EN 60551:1997
SIST EN 60551:1997/A1:1998
Power transformers - Part 10: Determination of sound levels (IEC 60076-10:2001)
Power transformers -- Part 10: Determination of sound levels
Leistungstransformatoren -- Teil 10: Bestimmung der Geräuschpegel
Transformateurs de puissance -- Partie 10: Détermination des niveaux de bruit
Ta slovenski standard je istoveten z: EN 60076-10:2001
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
29.180 Transformatorji. Dušilke Transformers. Reactors
SIST EN 60076-10:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD EN 60076-10
NORME EUROPÉENNE
EUROPÄISCHE NORM July 2001
ICS 29.180 Supersedes EN 60551:1992 + A1:1997
English version
Power transformers
Part 10: Determination of sound levels
(IEC 60076-10:2001)
Transformateurs de puissance Leistungstransformatoren
Partie 10: Détermination des Teil 10: Bestimmung der Geräuschpegel
niveaux de bruit (IEC 60076-10:2001)
(CEI 60076-10:2001)
This European Standard was approved by CENELEC on 2001-06-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60076-10:2001 E
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EN 60076-10:2001 - 2 -
Foreword
The text of document 14/390/FDIS, future edition 1 of IEC 60076-10, prepared by IEC TC 14, Power
transformers, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60076-10 on 2001-06-01.
This European Standard supersedes EN 60551:1992 + A1:1997.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-03-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-06-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA is normative and annexes A and B are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60076-10:2001 was approved by CENELEC as a European
Standard without any modification.
__________
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- 3 - EN 60076-10:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60076 Series Power transformers EN 60076 Series
IEC 60289 (mod) 1988 Reactors EN 60289 1994
IEC 60651 1979 Sound level meters EN 60651 1994
1)
IEC 60726 (mod) 1982 Dry-type power transformers HD 464 S1 1988
+ A2 1991
+ A3 1992
+ A4 1995
IEC 61043 1993 Electroacoustics - Instruments for the EN 61043 1994
measurement of sound intensity -
Measurement with pairs of pressure
sensing microphones
IEC 61378 Series Convertor transformers EN 61378 Series
ISO 3746 1995 Acoustics - Determination of sound EN ISO 3746 1995
power levels of noise sources using
sound pressure - Survey method using
an enveloping measurement surface
over a reflecting plane
ISO 9614-1 1993 Acoustics - Determination of sound EN ISO 9614-1 1995
power levels of noise sources using
sound intensity - Part 1: Measurement
at discrete points
1)
HD 464 S1 includes A1:1986 to IEC 60726:1982.
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NORME CEI
INTERNATIONALE IEC
60076-10
INTERNATIONAL
Première édition
STANDARD
First edition
2001-05
Transformateurs de puissance –
Partie 10:
Détermination des niveaux de bruit
Power transformers –
Part 10:
Determination of sound levels
© IEC 2005 Droits de reproduction réservés ⎯ Copyright - all rights reserved
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For price, see current catalogue
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60076-10 © IEC:2005 – 3 –
CONTENTS
FOREWORD.5
INTRODUCTION.9
1 Scope.13
2 Normative references .13
3 Terms and definitions .15
4 Instrumentation and calibration.17
5 Choice of test method.17
6 Load conditions .19
6.1 General .19
6.2 No-load current and rated voltage .19
6.3 Rated current and short-circuit voltage .19
6.4 Reduced-load current .21
7 Principal radiating surface .21
7.1 General .21
7.2 Transformers with or without cooling auxiliaries, dry-type transformers in
enclosures and dry-type transformers with cooling auxiliaries inside the
enclosure .21
7.3 Cooling auxiliaries mounted on a separate structure spaced ≥3 m away from
the principal radiating surface of the transformer.23
7.4 Dry-type transformers without enclosures.23
8 Prescribed contour .23
9 Microphone positions.23
10 Calculation of the area of the measurement surface .25
10.1 Measurements made at 0,3 m from the principal radiating surface.25
10.2 Measurements made at 2 m from the principal radiating surface.25
10.3 Measurements made at 1 m from the principal radiating surface.25
10.4 Measurements on test objects where safety clearance considerations require
a measurement distance which for all or part of the prescribed contour(s)
exceeds the provisions of 10.1 to 10.3 .25
11 Sound pressure method.27
11.1 Test environment.27
11.2 Sound pressure level measurements .31
11.3 Calculation of average sound pressure level .33
12 Sound intensity method .35
12.1 Test environment.35
12.2 Sound intensity level measurements .37
12.3 Calculation of average sound intensity level .37
13 Calculation of sound power level .39
14 Addition of no-load and load current sound power levels .39
15 Far-field calculations .41
16 Presentation of results.41
Annex A (informative) Narrow-band and time-synchronous measurements .57
Annex B (informative) Typical report of sound level determination .61
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60076-10 © IEC:2005 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POWER TRANSFORMERS –
Part 10: Determination of sound levels
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 in addition to other activities, IEC publishes International Standards, Technical Specifications,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
International Standard IEC 60076-10 has been prepared by IEC technical committee 14:
Power transformers.
This first edition of IEC 60076-10 cancels and replaces IEC 60551, published in 1987 and its
amendment 1 (1995), and constitutes a technical revision.
This bilingual version (2005-07) replaces the English version.
The text of this standard is based on the following documents:
FDIS Report on voting
14/390/FDIS 14/394/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
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60076-10 © IEC:2005 – 7 –
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 60076 consists of the following parts, under the general title Power transformers:
Part 1: General
Part 2: Temperature rise
Part 3: Insulation levels, dielectric tests and external clearances in air
Part 4: Guide to the lightning impulse and switching impulse testing – Power transformers
and reactors
Part 5: Ability to withstand short circuit
Part 6: Reactors
Part 7: Loading guide for oil-immersed power transformers
Part 8: Application guide
Part 10: Determination of sound levels
Part 11: Dry-type transformers
Part 13: Self protected liquid filled transformers
Part 14: Design and application of liquid-immersed power transformers using high-
temperature insulation materials
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
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60076-10 © IEC:2005 – 9 –
INTRODUCTION
One of the many parameters to be considered when designing and siting transformers,
reactors and their associated cooling equipment is the amount of sound that the equipment is
likely to emit under normal operating conditions on site.
Sources of sound
The audible sound radiated by transformers is generated by a combination of magnetostrictive
deformation of the core and electromagnetic forces in the windings, tank walls and magnetic
shields. Historically, the sound generated by the magnetic field inducing longitudinal
vibrations in the core laminations has been dominant. The amplitude of these vibrations
depends on the flux density in the laminations and the magnetic properties of the core steel,
and is therefore independent of the load current. Recent advances in core design, combined
with the use of low induction levels, have reduced the amount of sound generated in the core
such that the sound caused by the electromagnetic forces may become significant.
Current flowing in the winding conductors produces electromagnetic forces in the windings. In
addition, stray magnetic fields may induce vibrations in structural components. The force (and
therefore the amplitude of the vibrations) is proportional to the square of the current, and the
radiated sound power is proportional to the square of the vibrational amplitude. Consequently,
the radiated sound power is strongly dependent on the load current. Vibrations in core and
winding assemblies can then induce sympathetic vibrations in tank walls, magnetic shields
and air ducts (if present).
In the case of dry-type, air-cored shunt or series reactors, sound is generated by
electromagnetic forces acting on the windings in a similar manner to that described above.
These oscillatory forces cause the reactor to vibrate both axially and radially, and the axial
and radial supports and manufacturing tolerances may result in the excitation of modes in
addition to those of rotational symmetry. In the case of iron-cored reactors, further vibrations
are induced by forces acting in the magnetic circuit.
For all electrical plants, the consequence of the presence of higher harmonics on the power
supply should be understood. Normally, vibrations occur at even harmonics of the power
frequency, with the first harmonic being dominant. If other frequencies are present in the
power supply, other forces may be induced. For certain applications, this may be significant,
particularly because the human ear is more sensitive to these higher frequencies.
Any associated cooling equipment will also generate noise when operating. Fans and pumps
both tend to generate broad-band noise due to the forced flow of air or oil.
Measurement of sound
Sound level measurements have been developed to quantify pressure variations in air that a
human ear can detect. The smallest pressure variation that a healthy human ear can detect is
20 µPa. This is the reference level (0 dB) to which all the other levels are compared. The
perceived loudness of a signal is dependent upon the sensitivity of the human ear to its
frequency spectrum. Modern measuring instruments process sound signals through electronic
networks, the sensitivity of which varies with frequency in a manner similar to the human ear.
This has resulted in a number of internationally standardized weightings of which the A-
weighting network is the most common.
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60076-10 © IEC:2005 – 11 –
Sound intensity is defined as the rate of energy flow per unit area and is measured in watts
per square metre. It is a vector quantity whereas, sound pressure is a scalar quantity and is
defined only by its magnitude.
Sound power is the parameter which is used for rating and comparing sound sources. It is a
basic descriptor of a source’s acoustic output, and therefore an absolute physical property of
the source alone which is independent of any external factors such as environment and
distance to the receiver.
Sound power can be calculated from sound pressure or sound intensity determinations.
Sound intensity measurements have the following advantages over sound pressure
measurements:
• an intensity meter responds only to the propagating part of a sound field and ignores any
non-propagating part, for example, standing waves and reflections;
• the intensity method reduces the influence of external sound sources, as long as their
sound level is approximately constant.
The sound pressure method takes the above factors into account by correcting for
background noise and reflections.
For a detailed discussion of these measuring techniques, see IEC 60076-10-1: Determination
of sound levels – Application guide.
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60076-10 © IEC:2005 – 13 –
POWER TRANSFORMERS –
Part 10: Determination of sound levels
1 Scope
This part of IEC 60076 defines sound pressure and sound intensity measurement methods by
which sound power levels of transformers, reactors and their associated cooling auxiliaries
may be determined.
NOTE For the purpose of this standard, the term "transformer" means "transformer or reactor".
The methods are applicable to transformers and reactors covered by the IEC 60076 series,
IEC 60289, IEC 60076-11 and the IEC 61378 series, without limitation as regards size or
voltage and when fitted with their normal cooling auxiliaries.
This standard is primarily intended to apply to measurements made at the factory. Conditions
on-site may be very different because of the proximity of objects, including other trans-
formers. Nevertheless, the same general rules as are given in this standard may be followed
when on-site measurements are made.
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 60076 (all parts), Power transformers
IEC 60076-1:1993, Power transformers – Part 1: General
IEC 60076-11, Power transformers – Part 11: Dry-type transformers
IEC 60289:1988, Reactors
IEC 61043:1993, Electroacoustics – Instruments for the measurement of sound intensity –
Measurement with pairs of pressure sensing microphones
IEC 61378 (all parts), Convertor transformers
IEC 61672-1, Electroacoustics – Sound level meters – Part 1: Specifications
IEC 61672-2, Electroacoustics – Sound level meters – Part 2: Pattern evaluation tests
ISO 3746:1995, Acoustics – Determination of sound power levels of noise sources using
sound pressure – Survey method using an enveloping measurement surface over a reflecting
plane
ISO 9614-1:1993, Acoustics – Determination of sound power levels of noise sources using
sound intensity – Part 1: Measurement at discrete points
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60076-10 © IEC:2005 – 15 –
3 Terms and definitions
For the purpose of this document, the definitions in IEC 60076-1, as well as the following
definitions, apply.
3.1
sound pressure
p
fluctuating pressure superimposed on the static pressure by the presence of sound. It is
expressed in pascals
3.2
sound pressure level
L
p
ten times the logarithm to the base 10 of the ratio of the square of the sound pressure to the
–6
square of the reference sound pressure (p = 20 × 10 Pa). It is measured in decibels
0
2
p
L = 10 lg (1)
p
2
p
0
3.3
sound intensity
I
vector quantity describing the amount and direction of the net flow of sound energy at a given
–2
position. The unit is Wm
3.4
normal sound intensity
I
n
component of the sound intensity in the direction normal to a measurement surface
3.5
normal sound intensity level
L
I
ten times the logarithm to the base 10 of the ratio of the normal sound intensity to the
–12 –2
reference sound intensity (I = 1 × 10 Wm ). It is expressed in decibels
0
I
n
L = 10 lg (2)
I
I
0
NOTE When I is negative, the level is expressed as –XX dB.
n
3.6
sound power
W
rate at which airborne sound energy is radiated by a source. It is expressed in watts
3.7
sound power level
L
W
ten times the logarithm to the base 10 of the ratio of a given sound power to the reference
–12
sound power (W = 1 × 10 W). It is expressed in decibels
0
W
L = 10lg (3)
W
W
0
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60076-10 © IEC:2005 – 17 –
3.8
principal radiating surface
hypothetical surface surrounding the test object which is assumed to be the surface from
which sound is radiated
3.9
prescribed contour
horizontal line on which the measuring positions are located, spaced at a definite horizontal
distance (the "measurement distance") from the principal radiating surface
3.10
measurement distance
X
horizontal distance between the principal radiating surface and the "measurement surface"
3.11
measurement surface
hypothetical surface enveloping the source and on which the measurement points are located
3.12
background noise
A-weighted sound pressure level with the test object inoperative
4 Instrumentation and calibration
Sound pressure measurements shall be made using a type 1 sound level meter complying
with IEC 61672-1 and IEC 61672-2 and calibrated in accordance with 5.2 of ISO 3746.
Sound intensity measurements shall be made using a class 1 sound intensity instrument
complying with IEC 61043 and calibrated in accordance with 6.2 of ISO 9614-1. The
frequency range of the measuring equipment shall be adapted to the frequency spectrum of
the test object, that is, an appropriate microphone spacer system shall be chosen in order to
minimize systematic errors.
The measuring equipment shall be calibrated immediately before and after the measurement
sequence. If the calibration changes by more than 0,3 dB, the measurements shall be
declared invalid and the test repeated.
5 Choice of test method
Either sound pressure or sound intensity measurements may be used to determine the value
of the sound power level. Both methods are valid and either can be used, as agreed between
manufacturer and purchaser at the time of placing the order.
The sound pressure method of measurement described in this standard is in accordance with
ISO 3746. Measurements made in conformity with this standard tend to result in standard
deviations of reproducibility between determinations made in different laboratories which are
less than or equal to 3 dB.
The sound intensity method of measurement described in this standard is in accordance with
ISO 9614-1. Measurements made in conformity with this standard tend to result in standard
deviations of reproducibility between determinations made in different laboratories which are
less than or equal to 3 dB.
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60076-10 © IEC:2005 – 19 –
6 Load conditions
6.1 General
Load condition(s) shall be agreed between the manufacturer and purchaser at the time of
placing the order. If a transformer has a very low no-load sound level, the sound due to load
current can influence the total sound level in service. The method to be used for summing the
no-load and load current sound levels is given in Clause 14.
Current taken by a reactor is dependent on the voltage applied and consequently, a reactor
cannot be tested at no-load. Where sufficient power is available in the factory to permit full
energization of reactors, the methods to be followed are the same as those for transformers.
Alternatively, measurements may be made on-site if conditions are suitable.
Unless otherwise specified, the tests shall be carried out with the tap-changer (if any) on the
principal tapping. However, this tap position may not give the maximum sound level in
service. In addition, when the transformer is in service, a superposition of the flux at no-load
conditions and the stray flux occurs which causes a change in the flux density in certain parts
of the core. Therefore, under special conditions of intended application of a transformer
(particularly variable flux voltage variation), it may be agreed to measure the sound levels on
a tapping other than the principal tapping, or with a voltage other than the rated voltage on an
untapped winding. This shall be clearly indicated in the test report.
6.2 No-load current and rated voltage
For measurements made on the test object with or without its auxiliary cooling plant, the test
object shall be on no-load and excited at the rated voltage of sinusoidal or practically
sinusoidal waveform and rated frequency. The voltage shall be in accordance with 10.5 of
IEC 60076-1. If a transformer is fitted with reactor-type on-load tap-changer equipment where
the reactor may on certain tap-change positions be permanently energized, the measure-
ments shall be made with the transformer on a tapping which involves this condition and
which is as near to the principal tapping as possible. The excitation voltage shall be
appropriate to the tapping in use.
...
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