Acoustics - Test code for the measurement of airborne noise emitted by rotating electrical machines (ISO 1680:2013)

ISO 1680 specifies all the information necessary to carry out efficiently and under standardized conditions the determination, declaration, and verification of the noise emission characteristics of rotating electrical machines. It specifies noise measurement methods that can be used, and specifies the operating and mounting conditions required for the test. Noise emission characteristics include the sound power level and emission sound pressure level. The determination of these quantities is necessary: - for comparing the noise emitted by machines; - to enable manufacturers to declare the noise emitted; and - for the purposes of noise control. The use of this International Standard as a noise test code ensures the reproducibility of the determination of the noise emission characteristics within specified limits determined by the grade of accuracy of the basic noise measurement method used. Noise measurement methods allowed by this International Standard are precision methods (grade 1), engineering methods (grade 2) and survey methods (grade 3). Methods of engineering grade (grade 2) are to be preferred. This International Standard is applicable to rotating electrical machines of any length, width or height.

Akustik - Verfahren zur Messung der Luftschallemission von drehenden elektrischen Maschinen (ISO 1680:2013)

Diese Internationale Norm enthält alle erforderlichen Informationen zur effizienten und einheitlichen Bestim-mung, Angabe und Nachprüfung der Geräuschemissionskennwerte von drehenden elektrischen Maschinen. Sie legt anwendbare Geräuschmessverfahren fest, sowie die Aufstellungs- und Betriebsbedingungen, die für die Prüfung erforderlich sind.
Die Geräuschemissionskennwerte umfassen den Schallleistungspegel und den Emissions-Schalldruckpegel. Die Bestimmung dieser Größen ist erforderlich
- zum Vergleich der Geräuschemission von Maschinen,
- um den Herstellern die Angabe der Geräuschemission zu ermöglichen, sowie
- für Zwecke der Geräuschminderung.
Die Verwendung dieser Internationalen Norm als Geräuschmessnorm stellt sicher, dass die Bestimmung der Geräuschemissionskennwerte innerhalb der durch die Genauigkeitsklasse des verwendeten grundlegenden Geräuschmessverfahrens festgelegten Grenzen reproduzierbar ist. Zulässige Geräuschmessverfahren nach dieser Internationalen Norm sind Präzisionsverfahren (Genauigkeitsklasse 1), Technische Verfahren (Genauigkeitsklasse 2) und Übersichtsverfahren (Genauigkeitsklasse 3). Technische Verfahren (Genauig-keitsklasse 2) sind zu bevorzugen.
Diese Internationale Norm gilt für drehende elektrische Maschinen beliebiger Länge, Breite oder Höhe.

Acoustique - Code d'essai pour le mesurage du bruit aérien émis par les machines électriques tournantes (ISO 1680:2013)

L'ISO 1680:2013 spécifie toutes les informations nécessaires à la réalisation efficace et dans les conditions normalisées de la détermination, de la déclaration et de la vérification des caractéristiques d'émission sonore des machines électriques tournantes. Elle spécifie les méthodes de mesure du bruit pouvant être utilisées ainsi que les conditions de fonctionnement et de montage qui doivent être utilisées pour l'essai.
Les caractéristiques d'émission sonore comprennent les niveaux de puissance acoustique et de pression acoustique d'émission. La détermination de ces grandeurs est nécessaire pour comparer le bruit rayonné par les machines, permettre aux fabricants de déclarer le bruit rayonné et réduire le bruit.
L'utilisation de l'ISO 1680:2013 comme code d'essai acoustique permet de reproduire la détermination des caractéristiques d'émission sonore dans les limites spécifiées déterminées par la classe de précision de la méthode de mesure de base utilisée. L'ISO 1680:2013 autorise l'utilisation de méthodes de mesure du bruit (classe 1), de méthodes d'expertise (classe 2) et de méthodes de contrôle (classe 3), comme méthodes de mesurage du bruit. Les méthodes de classe expertise (classe 2) sont à préférer.
L'ISO 1680:2013 s'applique aux machines électriques tournantes de dimension linéaire (longueur, largeur ou hauteur) quelconque.

Akustika - Preskusni postopek za merjenje hrupa v zraku, ki ga povzročajo električni rotirajoči stroji (ISO 1680:2013)

General Information

Status
Published
Public Enquiry End Date
09-Jul-2013
Publication Date
12-Jan-2014
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
23-Dec-2013
Due Date
27-Feb-2014
Completion Date
13-Jan-2014

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SLOVENSKI STANDARD
SIST EN ISO 1680:2014
01-februar-2014
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SIST EN ISO 1680:2001
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Acoustics - Test code for the measurement of airborne noise emitted by rotating
electrical machines (ISO 1680:2013)

Akustik - Verfahren zur Messung der Luftschallemission von drehenden elektrischen

Maschinen (ISO 1680:2013)
Acoustique - Code d'essai pour le mesurage du bruit aérien émis par les machines
électriques tournantes (ISO 1680:2013)
Ta slovenski standard je istoveten z: EN ISO 1680:2013
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
29.160.01 Rotacijski stroji na splošno Rotating machinery in
general
SIST EN ISO 1680:2014 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 1680:2014
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SIST EN ISO 1680:2014
EUROPEAN STANDARD
EN ISO 1680
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2013
ICS 17.140.20; 29.160.01 Supersedes EN ISO 1680:1999
English Version
Acoustics - Test code for the measurement of airborne noise
emitted by rotating electrical machines (ISO 1680:2013)

Acoustique - Code d'essai pour le mesurage du bruit aérien Akustik - Verfahren zur Messung der Luftschallemission von

émis par les machines électriques tournantes (ISO drehenden elektrischen Maschinen (ISO 1680:2013)

1680:2013)
This European Standard was approved by CEN on 12 August 2013.

CEN 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 CEN-CENELEC Management Centre or to any CEN 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 CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same

status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 1680:2013 E

worldwide for CEN national Members.
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SIST EN ISO 1680:2014
EN ISO 1680:2013 (E)
Contents Page

Foreword ..............................................................................................................................................................3

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SIST EN ISO 1680:2014
EN ISO 1680:2013 (E)
Foreword

This document (EN ISO 1680:2013) has been prepared by Technical Committee ISO/TC 43 “Acoustics” in

collaboration with Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DS.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by June 2014, and conflicting national standards shall be withdrawn at

the latest by June 2014.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 1680:1999.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech

Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 1680:2013 has been approved by CEN as EN ISO 1680:2013 without any modification.

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SIST EN ISO 1680:2014
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SIST EN ISO 1680:2014
INTERNATIONAL ISO
STANDARD 1680
Second edition
2013-12-15
Acoustics — Test code for the
measurement of airborne noise
emitted by rotating electrical
machines
Acoustique — Code d’essai pour le mesurage du bruit aérien émis par
les machines électriques tournantes
Reference number
ISO 1680:2013(E)
ISO 2013
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Description of machinery family ......................................................................................................................................................... 4

5 Sound power determination .................................................................................................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Guidelines for the selection of the most appropriate basic standard ...................................................... 5

5.3 Additional requirements ................................................................................................................................................................ 5

6 Installation and mounting conditions ............................................................................................................................................ 8

6.1 Mounting of the machine ............................................................................................................................................................... 8

6.2 Auxiliary equipment and loaded machines .................................................................................................................... 9

7 Operating conditions ....................................................................................................................................................................................... 9

7.1 General ........................................................................................................................................................................................................... 9

7.2 Load ...............................................................................................................................................................................................................10

7.3 Variable speed devices ..................................................................................................................................................................10

8 Measurement uncertainty .......................................................................................................................................................................10

9 Determination of the emission sound pressure level .................................................................................................12

9.1 General ........................................................................................................................................................................................................12

9.2 Selection of the relevant work station .............................................................................................................................12

9.3 Selection of basic standard to be used .............................................................................................................................12

9.4 Measurement uncertainty ..........................................................................................................................................................12

10 Indication of noise emission quantities determined according to this

International Standard ...............................................................................................................................................................................12

11 Information to be recorded ....................................................................................................................................................................13

12 Information to be reported ....................................................................................................................................................................13

13 Declaration and verification of noise emission values (if required)
..........................................................13

Annex A (informative) Overview of standards for the determination of sound power levels of

machines and equipment .........................................................................................................................................................................15

Annex B (informative) Example of a dual-number declaration for rotating electrical machines .....18

Bibliography .............................................................................................................................................................................................................................19

© ISO 2013 – All rights reserved iii
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2, www.iso.org/directives.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received, www.iso.org/patents.

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

The committee responsible for this document is ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

This second edition cancels and replaces the first edition (ISO 1680:1999), which has been technically

revised.
iv © ISO 2013 – All rights reserved
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SIST EN ISO 1680:2014
INTERNATIONAL STANDARD ISO 1680:2013(E)
Acoustics — Test code for the measurement of airborne
noise emitted by rotating electrical machines
1 Scope

This International Standard specifies all the information necessary to carry out efficiently and

under standardized conditions the determination, declaration, and verification of the noise emission

characteristics of rotating electrical machines. It specifies noise measurement methods that can be

used, and specifies the operating and mounting conditions required for the test.

Noise emission characteristics include the sound power level and emission sound pressure level. The

determination of these quantities is necessary:
— for comparing the noise emitted by machines;
— to enable manufacturers to declare the noise emitted; and
— for the purposes of noise control.

The use of this International Standard as a noise test code ensures the reproducibility of the

determination of the noise emission characteristics within specified limits determined by the grade of

accuracy of the basic noise measurement method used. Noise measurement methods allowed by this

International Standard are precision methods (grade 1), engineering methods (grade 2) and survey

methods (grade 3). Methods of engineering grade (grade 2) are to be preferred.

This International Standard is applicable to rotating electrical machines of any length, width or height.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 3741, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Precision methods for reverberation test rooms

ISO 3743-1, Acoustics — Determination of sound power levels and sound energy levels of noise sources

using sound pressure — Engineering methods for small movable sources in reverberant fields — Part 1:

Comparison method for a hard-walled test room

ISO 3743-2, Acoustics — Determination of sound power levels of noise sources using sound pressure —

Engineering methods for small, movable sources in reverberant fields — Part 2: Methods for special

reverberation test rooms

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

ISO 3745:2012, Acoustics — Determination of sound power levels and sound energy levels of noise sources

using sound pressure — Precision methods for anechoic rooms and hemi-anechoic rooms

ISO 3746, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Survey method using an enveloping measurement surface over a reflecting plane

ISO 3747, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Engineering/survey methods for use in situ in a reverberant environment

© ISO 2013 – All rights reserved 1
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SIST EN ISO 1680:2014
ISO 1680:2013(E)

ISO 4871:1996, Acoustics — Declaration and verification of noise emission values of machinery and

equipment

ISO 7574-4, Acoustics — Statistical methods for determining and verifying stated noise emission values of

machinery and equipment — Part 4: Methods for stated values for batches of machines

ISO 9614-1, Acoustics — Determination of sound power levels of noise sources using sound intensity —

Part 1: Measurement at discrete points

ISO 9614-2, Acoustics — Determination of sound power levels of noise sources using sound intensity —

Part 2: Measurement by scanning

ISO 9614-3, Acoustics — Determination of sound power levels of noise sources using sound intensity —

Part 3: Precision method for measurement by scanning

ISO 11203, Acoustics — Noise emitted by machinery and equipment — Determination of emission sound

pressure levels at a work station and at other specified positions from the sound power level

IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
time averaged sound pressure level
p,T

ten times the logarithm to the base 10 of the ratio of the time average of the square of the sound pressure,

p, during a stated time interval of duration, T (starting at t and ending at t ), to the square of a reference

1 2
value, p , expressed in decibels
 2 
 
pt()dt
T 
 
LL==10lg dB
pT,,pTeq
 
 
 
 
where the reference value, p , is 20 µPa

Note 1 to entry: Because of practical limitations of the measuring instruments, p is always understood to denote

the square of a frequency-weighted and frequency-band-limited sound pressure. If a specific frequency weighting

as specified in IEC 61672-1 and/or specific frequency bands are applied, this should be indicated by appropriate

subscripts; e.g. L denotes the A-weighted time-averaged sound pressure level over 10 s.

p,A,10 s
3.2
measurement surface

hypothetical surface of area S, enveloping the source on which the measurement points are located

Note 1 to entry: The measurement surface terminates on one or more reflecting planes.

2 © ISO 2013 – All rights reserved
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
3.3
surface sound pressure level

energy average of the time-averaged sound pressure levels at all the microphone positions on the

measurement surface, with the background noise correction K and the environmental correction K

1 2
applied
Note 1 to entry: It is expressed in decibels.
3.4
sound intensity

time-averaged value of the product of the instantaneous sound pressure and the associated sound

velocity at a point in a temporally stationary sound field
3.5
normal sound intensity level

ten times the logarithm to the base 10 of the ratio of the unsigned value of the normal component of

the sound intensity (which is radiated by the sound source under test and determined in a direction

perpendicular to the measurement surface) to the reference sound intensity
Note 1 to entry: It is expressed in decibels.
–12 –2
Note 2 to entry: The reference sound intensity is 10 Wm .
3.6
sound power level

ten times the logarithm to the base 10 of the ratio of the sound power, P, to a reference value, P , expressed

in decibels
L =10lg dB
where the reference value, P , is 1 pW

Note 1 to entry: If a specific frequency weighting as specified in IEC 61672-1 and/or specific frequency bands are

applied, this should be indicated by appropriate subscripts; e.g. L denotes the A-weighted sound power level.

W,A
[15]

Note 2 to entry: This definition is technically in accordance with ISO 80000-8:2007, 8-23 .

3.7
emission sound pressure

time-averaged sound pressure, at a specified position near a noise source, when the source is in operation

under specified operating and mounting conditions on a reflecting plane surface, excluding the effects of

background noise as well as the effects of reflections from room surfaces other than the plane or planes

permitted for the purpose of the test
Note 1 to entry: It is expressed in pascals.
3.8
emission sound pressure level

ten times the logarithm to the base 10 of the ratio of the square of the emission sound pressure, p (t), to

the square of the reference sound pressure, p , measured with a particular time weighting and a

particular frequency weighting, selected from those defined in IEC 61672-1

Note 1 to entry: It is expressed in decibels. The reference sound pressure is 20 µPa.

© ISO 2013 – All rights reserved 3
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SIST EN ISO 1680:2014
ISO 1680:2013(E)

EXAMPLE The A-weighted emission sound pressure level with time weighting F is denoted L . The

pAF
C-weighted peak emission sound pressure level is denoted L .
pC,peak
3.9
noise emission declaration

information on the noise emitted by the machine, given by the manufacturer or supplier in technical

documents or other literature concerning noise emission values

Note 1 to entry: The noise emission declaration may take the form of either the declared single-number noise

emission value or the declared dual-number noise emission value.
3.10
measured noise emission value

A-weighted sound power level, or the A-weighted time-averaged emission sound pressure level, or the

C-weighted peak emission sound pressure level, as determined from measurements

Note 1 to entry: Measured values may be determined either from a single machine or from the average of a number

of machines, and are not rounded.
3.11
declared single-number noise emission value

sum, rounded to the nearest whole decibel, of the measured noise emission value, L, and the associated

uncertainty, U:
L = L + U
3.12
declared dual-number noise emission value
L and U

measured noise emission value L, and its associated uncertainty U, both rounded to the nearest decibel

4 Description of machinery family

This International Standard is applicable to self-standing rotating electrical machines, i.e. motors and

generators (d.c. and a.c machines), without any limitation on the output or voltage, and with any linear

dimensions.

Families of devices covered by this International Standard include rotating electrical machines to be fed

by the following possibilities:
— a network (sinusoidal supply) whenever specially designed for that purpose;
— an associated converter.

In the case of supply by a converter, the noise radiated by the converter is excluded from the scope of

this International Standard; only the effect of non-sinusoidal voltage and current within the machine is

to be taken into account.

Auxiliary components required for the operation of the machine (e.g. oil pumps or cooling ventilators)

should be included when integrated with the machine. When these components are separately mounted,

they shall not be included as part of the machine under test.
4 © ISO 2013 – All rights reserved
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
5 Sound power determination
5.1 General

The sound power radiated by rotating electrical machines shall be determined on the basis of one of the

following basic standards:
— accuracy grade 1: ISO 3741, ISO 3745, ISO 9614-1, ISO 9614-3;

— accuracy grade 2: ISO 3743-1, ISO 3743-2, ISO 3744, ISO 3747, ISO 9614-1, ISO 9614-2.

Methods of engineering grade (grade 2) are to be preferred.

Furthermore, survey methods may also be used if it has been proved that no method with better

accuracy is practical:
— accuracy grade 3: ISO 3746, ISO 9614-1, ISO 9614-2.
5.2 Guidelines for the selection of the most appropriate basic standard
The usable basic standards are mainly distinguished by the following:
— different environmental conditions;

— different requirements with respect to the background noise levels related to the noise level of the

machine under test;
— different grades of accuracy;
— different quantities to be measured: sound pressure or sound intensity.

NOTE 1 Detailed guidelines for the selection of the most appropriate basic standards are given in ISO 3740.

The sound intensity measurement method has the following advantages as compared to the sound

pressure measurement method.

a) Determination of the correct sound power is possible regardless of whether the measurement

surface lies within or outside the near field.

b) Determination of the correct sound power is possible in the presence of noise fields where the sound

pressure method gives results which are so wrong that they would no longer conform to sound

pressure measurement standards.

c) It allows a better grade of accuracy for the sound power determination especially under the worst

environmental conditions (and therefore allows determination of the sound power level of machines

in the presence of noisy loading machines).
[4]

NOTE 2 Methods described in ISO/TS 7849 allow that part of the radiated airborne sound power caused by

the vibrating outer surface of the machine to be determined separately.

A description of the fields of application of the main basic standards is given in Table 1, supplemented by

Figure 1. A more precise distinction of these standards is shown in Annex A.
5.3 Additional requirements

Each of the basic standards gives detailed and precise requirements for all acoustical aspects of the

relevant measurement procedure, such as definition of the measurement surface, if any, microphone

array, environmental adequacy, determination of environmental and background noise corrections,

if relevant, together with requirements for instrumentation. These standards leave open precise

definitions of mounting and operating conditions which shall be stated in the machinery-specific noise

test code. These requirements are given in Clause 6.
© ISO 2013 – All rights reserved 5
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SIST EN ISO 1680:2014
ISO 1680:2013(E)

When applying ISO 3744 or ISO 3746 which use sound pressure measurements under more or less free-

field conditions, a parallelepiped measurement surface shall be used to facilitate the location of the

microphone positions.

Supplementing the general rules for rotating electrical machines, the following simplifications may be

used.

a) The arrangement of the measurement positions may, especially for large machines, be simplified

if, for a specific type of machine, it can be shown, with the help of preliminary investigations on

machines of that specific type, that the sound field is adequately uniform and that measurements

lead to values of sound power level deviating by no more than 0,5 dB for grade 2 methods and

1 dB (A-weighted) for grade 3 methods from those determined with a complete arrangement of

measurement positions.

b) For sources that produce a symmetrical radiation pattern, it may be sufficient to distribute the

measurement positions over only a portion of the measurement surface. This is acceptable only

if, for a specific type of machine, it can be shown, with the help of preliminary investigations on

machines of that specific type, that the measurements lead to values of sound power level deviating

by no more than 0,5 dB for grade 2 methods and 1 dB (A-weighted) for grade 3 methods from those

determined with a complete arrangement of measurement positions.

c) If required to check the presence of prominent discrete tone(s), the so called “magnetic noise”, being

typical of rotating electrical machines, should be taken into consideration with preference. Under

no-load operating conditions, this noise component is weak and do not disturb in general, but may

increase significantly under loading conditions.

Consequently the following alternative tonality tests are useful for rotating electrical machines:

1) measuring the A-weighted sound power level, L , caused by changing the operating conditions

W,A

from no-load to rated load to determine the relevant difference ΔL , in decibels; or

W,A
[9]
NOTE This test is used by IEC 60034-9 where limit values for ΔL are given.
W,A

2) measuring the one-third-octave band pressure spectrum under rated load conditions at the

measurement position with the highest value of L , and calculation of the difference between

p,A,T
each protruding level and its two adjacent band levels.

Differences larger than 6 dB can be characterized as prominent for the frequency range from 500 Hz

to 10 000 Hz; or
[3]

3) determining the tonality under rated load conditions according to ISO 7779:2010, Annex D.

6 © ISO 2013 – All rights reserved
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SIST EN ISO 1680:2014
ISO 1680:2013(E)
Table 1 — Sound
...

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