IEC 60076-10-1:2016

Power transformers - Part 10-1: Determination of sound levels - Application guide

IEC 60076-10-1:2016 provides supporting information to help both manufacturers and purchasers to apply the measurement techniques described in IEC 60076-10. Besides the introduction of some basic acoustics, the sources and characteristics of transformer and reactor sound are described. Practical guidance on making measurements is given, and factors influencing the accuracy of the methods are discussed. This application guide also indicates why values measured in the factory may differ from those measured in service. This application guide is applicable to transformers and reactors together with their associated cooling auxiliaries. This edition includes the following significant technical changes with respect to the previous edition:
a) extended information on sound fields provided;
b) effect of current harmonics in windings enfolded;
c) updated information on measuring methods sound pressure and sound intensity given;
d) supporting information on measuring procedures walk-around and point-by-point given;
e) clarification of A-weighting provided;
f) new information on frequency bands given;
g) background information on measurement distance provided;
h) new annex on sound-built up due to harmonic currents in windings introduced.
This publication is to be read in conjunction with IEC 60076-10:2016.

Transformateurs de puissance - Partie 10-1: Détermination des niveaux de bruit - Guide d'application

L'IEC 60076-10-1:2016 fournit des informations visant à aider les fabricants et les acheteurs à appliquer les techniques de mesure décrites dans l'IEC 60076-10. Outre l'introduction de certaines notions acoustiques de base, les sources et caractéristiques relatives aux transformateurs et aux bobines d'inductance sont décrites. Des lignes directrices pratiques relatives aux mesures sont fournies, et les facteurs exerçant une influence sur la précision des méthodes sont abordés. Le présent guide d'application indique également pourquoi les valeurs mesurées en usine peuvent différer de celles mesurées en service. Le présent guide d'application s'applique aux transformateurs et aux bobines d'inductance ainsi qu'à leurs auxiliaires de refroidissement associés. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout d'informations étendues relatives aux champs acoustiques;
b) intégration de l'effet des harmoniques réels sur les enroulements;
c) ajout d'informations mises à jour sur les méthodes de mesure en pression acoustique et sur l'intensité acoustique;
d) informations à l'appui relatives aux procédures de mesure d'inspection en continu et point par point;
e) ajout d'une clarification de la pondération A;
f) ajout de nouvelles informations sur les bandes de fréquence;
g) ajout d'informations de contexte sur la distance de mesure;
h) introduction d'une nouvelle annexe sur l'augmentation acoustique due aux courants harmoniques dans les enroulements.
Cette publication doit être lue conjointement avec la IEC 60076-10:2016.

General Information

• Status: Published
• Publication Date: 01-Nov-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: TC 14 - Power transformers
• Drafting Committee: MT 60076-10 - TC 14/MT 60076-10
• Current Stage: PPUB - Publication issued
• Start Date: 15-May-2016
• Completion Date: 24-Mar-2016

Relations

• Amended By: IEC 60076-10-1:2016/AMD1:2020 - Amendment 1 - Power transformers - Part 10-1: Determination of sound levels - Application guide
• Effective Date: 05-Sep-2023
• Revises: IEC 60076-10-1:2005 - Power transformers - Part 10-1: Determination of sound levels - Application guide
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60076-10-1 ®
Edition 2.1 2020-11
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Power transformers –
Part 10-1: Determination of sound levels – Application guide

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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IEC 60076-10-1 ®
Edition 2.1 2020-11
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Power transformers –
Part 10-1: Determination of sound levels – Application guide

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.180 ISBN 978-2-8322-9027-9

IEC 60076-10-1 ®
Edition 2.1 2020-11
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
Power transformers –
Part 10-1: Determination of sound levels – Application guide

– 2 – IEC 60076-10-1:2016+AMD1:2020 CSV
 IEC 2020
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Basic physics of sound . 7
3.1 Phenomenon . 7
3.2 Sound pressure, p . 7
3.3 Particle velocity, u . 8
3.4 Sound intensity, . 8
I
3.5 Sound power, W . 8
3.6 Sound fields . 9
3.6.1 General . 9
3.6.2 The free field . 9
3.6.3 The diffuse field . 9
3.6.4 The near-field . 9
3.6.5 The far-field . 10
3.6.6 Standing waves . 10
4 Sources and characteristics of transformer and reactor sound . 11
4.1 General . 11
4.2 Sound sources . 11
4.2.1 Core . 11
4.2.2 Windings . 14
4.2.3 Stray flux control elements . 14
4.2.4 Sound sources in reactors . 15
4.2.5 Effect of current harmonics in transformer and reactor windings . 15
4.2.6 Fan noise . 18
4.2.7 Pump noise . 18
4.2.8 Relative importance of sound sources . 18
4.3 Vibration transmission . 18
4.4 Sound radiation. 19
4.5 Sound field characteristics . 19
5 Measurement principles . 20
5.1 General . 20
5.2 A-weighting . 20
5.3 Sound measurement methods . 22
5.3.1 General . 22
5.3.2 Sound pressure method . 23
5.3.3 Sound intensity method . 24
5.3.4 Selection of appropriate sound measurement method . 27
5.4 Information on frequency bands . 27
5.5 Information on measurement surface . 29
5.6 Information on measurement distance . 29
5.7 Information on measuring procedures (walk-around and point-by-point) . 30
6 Practical aspects of making sound measurements . 31
6.1 General . 31
6.2 Orientation of the test object to avoid the effect of standing waves . 31
6.3 Device handling for good acoustical practice . 32

 IEC 2020
6.4 Choice of microphone spacer for the sound intensity method . 33
6.5 Measurements with tank mounted sound panels providing incomplete
coverage . 33
6.6 Testing of reactors . 34
7 Difference between factory tests and field sound level measurements . 34
7.1 General . 34
7.2 Operating voltage . 34
7.3 Load current . 34
7.4 Load power factor and power flow direction . 35
7.5 Operating temperature . 35
7.6 Harmonics in the load current and in voltage . 35
7.7 DC magnetization . 36
7.8 Effect of remanent flux . 36
7.9 Sound level build-up due to reflections . 36
7.10 Converter transformers with saturable reactors (transductors) . 37
Annex A (informative) Sound level built up due to harmonic currents in windings . 38
A.1 Theoretical derivation of winding forces due to harmonic currents . 38
A.2 Force components for a typical current spectrum caused by a B6 bridge. 39
A.3 Estimation of sound level increase due to harmonic currents by calculation . 42
Bibliography . 44

Figure 1 – Simulation of the spatially averaged sound intensity level (solid lines) and
sound pressure level (dashed lines) versus measurement distance d in the near-field . 10
Figure 2 – Example curves showing relative change in lamination length for one type
of electrical core steel during complete cycles of applied 50 Hz a.c. induction up to

peak flux densities B in the range of 1,2 T to 1,9 T . 11
max
Figure 3 – Induction (smooth line) and relative change in lamination length (dotted line)
as a function of time due to applied 50 Hz a.c. induction at 1,8 T – no d.c. bias . 12
Figure 4 – Example curve showing relative change in lamination length during one
complete cycle of applied 50 Hz a.c. induction at 1,8 T with a small d.c. bias of 0,1 T . 12
Figure 5 – Induction (smooth line) and relative change in lamination length (dotted line)
as a function of time due to applied 50 Hz a.c. induction at 1,8 T with a small d.c. bias
of 0,1 T . 13
Figure 6 – Sound level increase due to d.c. current in windings . 13
Figure 7 – Typical sound spectrum due to load current . 14
Figure 8 – Simulation of a sound pressure field (coloured) of a 31,5 MVA transformer
at 100 Hz with corresponding sound intensity vectors along the measurement path . 20
Figure 9 – A-weighting graph derived from function A(f) . 21
Figure 10 – Distribution of disturbances to sound pressure in the test environment . 24
Figure 11 – Microphone arrangement . 25
Figure 12 – Illustration of background sound passing through test area and sound
radiated from the test object . 26
Figure 13 – 1/1- and 1/3-octave bands with transformer tones for 50 Hz and 60 Hz
systems . 28
Figure 14 – Logging measurement demonstrating spatial variation along the
measurement path . 31
Figure 15 – Test environment . 32
Figure A.1 – Current wave shape for a star and a delta connected winding for the
current spectrum given in Table A.2 . 40

– 4 – IEC 60076-10-1:2016+AMD1:2020 CSV
 IEC 2020
Table 1 – A-weighting values for the first fifteen transformer tones . 22
Table A.1 – Force components of windings due to harmonic currents . 39
Table A.2 – Current spectrum of a B6 converter bridge .
...

IEC 60076-10-1 ®
Edition 2.0 2016-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Power transformers –
Part 10-1: Determination of sound levels – Application guide

Transformateurs de puissance –
Partie 10-1: Détermination des niveaux de bruit – Guide d'application

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IEC 60076-10-1 ®
Edition 2.0 2016-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Power transformers –
Part 10-1: Determination of sound levels – Application guide

Transformateurs de puissance –

Partie 10-1: Détermination des niveaux de bruit – Guide d'application

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180 ISBN 978-2-8322-3253-8

– 2 – IEC 60076-10-1:2016  IEC 2016
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references. 7
3 Basic physics of sound . 7
3.1 Phenomenon . 7
3.2 Sound pressure, p . 7
3.3 Particle velocity, u . 8
3.4 Sound intensity, I . 8
3.5 Sound power, W . 8
3.6 Sound fields . 9
3.6.1 General . 9
3.6.2 The free field . 9
3.6.3 The diffuse field . 9
3.6.4 The near-field . 9
3.6.5 The far-field . 10
3.6.6 Standing waves . 10
4 Sources and characteristics of transformer and reactor sound . 11
4.1 General . 11
4.2 Sound sources . 11
4.2.1 Core . 11
4.2.2 Windings . 14
4.2.3 Stray flux control elements . 14
4.2.4 Sound sources in reactors . 15
4.2.5 Effect of current harmonics in transformer and reactor windings . 15
4.2.6 Fan noise . 18
4.2.7 Pump noise . 18
4.2.8 Relative importance of sound sources . 18
4.3 Vibration transmission . 18
4.4 Sound radiation . 19
4.5 Sound field characteristics . 19
5 Measurement principles . 20
5.1 General . 20
5.2 A-weighting . 20
5.3 Sound measurement methods . 22
5.3.1 General . 22
5.3.2 Sound pressure method . 23
5.3.3 Sound intensity method . 24
5.3.4 Selection of appropriate sound measurement method . 27
5.4 Information on frequency bands . 27
5.5 Information on measurement surface . 29
5.6 Information on measurement distance . 29
5.7 Information on measuring procedures (walk-around and point-by-point) . 30
6 Practical aspects of making sound measurements . 31
6.1 General . 31
6.2 Orientation of the test object to avoid the effect of standing waves . 31
6.3 Device handling for good acoustical practice . 32

6.4 Choice of microphone spacer for the sound intensity method . 33
6.5 Measurements with tank mounted sound panels providing incomplete
coverage . 33
6.6 Testing of reactors . 34
7 Difference between factory tests and field sound level measurements . 34
7.1 General . 34
7.2 Operating voltage . 34
7.3 Load current . 34
7.4 Load power factor and power flow direction . 35
7.5 Operating temperature . 35
7.6 Harmonics in the load current and in voltage . 35
7.7 DC magnetization . 36
7.8 Effect of remanent flux . 36
7.9 Sound level build-up due to reflections . 36
7.10 Converter transformers with saturable reactors (transductors) . 37
Annex A (informative) Sound level built up due to harmonic currents in windings . 38
A.1 Theoretical derivation of winding forces due to harmonic currents . 38
A.2 Force components for a typical current spectrum caused by a B6 bridge . 39
A.3 Estimation of sound level increase due to harmonic currents by calculation . 42
Bibliography . 44

Figure 1 – Simulation of the spatially averaged sound intensity level (solid lines) and
sound pressure level (dashed lines) versus measurement distance d in the near-field . 10
Figure 2 – Example curves showing relative change in lamination length for one type
of electrical core steel during complete cycles of applied 50 Hz a.c. induction up to
peak flux densities B in the range of 1,2 T to 1,9 T .
...