Iec 60076-10-2016.Pdf

IEC 60076 1 0 Edition 2 0 201 6 03 INTERNATIONAL STANDARD NORME INTERNATIONALE Power transformers – Part 1 0 Determination of sound levels Transformateurs de puissance – Partie 1 0 Détermination des n[.]

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CONTENTS

FOREWORD 4

INTRODUCTION 6

1 Sco e

8 2 Normative referen es 8

3 Terms an definition 9

4 Sou d p wer for diferent lo din con ition 1

4.1 General 1

4.2 Sou d p wer at no-lo d ex itation 12 4.3 Sou d p wer of the co l n device(s) 12 4.4 Sou d p wer d e to lo d c r ent 12 5 Sou d level me s rement sp cification 14 6 In trumentation, cal bration an ac urac 15 7 Prin ip l radiatin s rface 16 7.1 General 16 7.2 Tran formers with or without co l n device 16 7.3 Tran formers in en los res with co ln devices in ide the en los re 16 7.4 Tran formers in en los res with co ln devices outside the en los re 17 7.5 Co l n devices mou ted on a se arate stru ture where the distan e b twe n the two prin ip l radiatin s rfaces is ≥ 3 m 17 7.6 Dry- yp tran formers 17 7.7 Dry- yp air-core re ctors 17 8 Pres rib d contour 18 9 Micro hone p sition 19 10 Calc lation of the me s rement s rface are 19 10.1 Me s rement s rface are for me s rin distan es up to 3 m 19 10.2 Me s rement s rface are for me s rin distan es larger than 3 m 19 1 Sou d me s rement 2

1 1 Test con ition 2

1 1.1 Placement of test o ject 2

1 1.2 Test energisation o tion 2

1 1.3 Test a pl cation detai s 21

1 1.4 Prevai n ambient con ition 21

1 2 Sou d pres ure method 21

1 2.1 General 21

1 2.2 Test proced re 21

1 2.3 Calc lation of the sp tial y averaged sou d pres ure level 2

1 2.4 Val dation of test me s rements with resp ct to b ckgrou d noise 2

1 2.5 Calc lation of en ironmental cor ection K 2

1 2.6 Final cor ection for ste d -state b ckgrou d noise an test en ironment 2

1 3 Sou d inten ity method 26 1 3.1 General 2

1 3.2 Test proced re 2

1 3.3 Calc lation of average normal sou d inten ity an sou d pres ure level 2

1 3.4 Me s rement val dation 2

12 Determination of sou d p wer level by calc lation 2

13 L garithmic ad ition an s btraction of in ivid al sou d levels 29 14 Far- ield calc lation for distan es larger than 3 m 3

15 Presentation of res lts 31

An ex A (informative) Nar ow-b n an time-s n hronou me s rements 4

A.1 General con ideration 4

A.2 Nar ow-b n me s rement 4

A.2.1 General 4

A.2.2 Post proces in of nar ow-b n me s rements to ex lu e b ckgrou d noise 41

A.3 Time-s n hronou averagin tec niq e 41

An ex B (informative) Typical re ort of sou d level determination 4

B.1 Sou d pres ure method 4

B.2 Sou d pres ure method – Ap en ix for the p int by-p int proced re 5

B.3 Sou d inten ity method 51 B.4 Sou d inten ity method – Ap en ix for the p int by-p int proced re 5

Bibl ogra h 6

Fig re 1 – Typical micro hone p th / p sition for sou d me s rement on tran formers ex lu in co l n devices 3

Fig re 2 – Typical micro hone p th / p sition for sou d me s rement on tran formers havin co l n devices mou ted either directly on the tank or on a se arate stru ture sp ced < 3 m away from the prin ip l radiatin s rface of the main tank 3

Fig re 3 – Typical micro hone p th / p sition for sou d me s rement on tran formers havin se arate co l n devices sp ced < 3 m away from the prin ip l radiatin s rface of the main tank 3

Fig re 4 – Typical micro hone p th / p sition for sou d me s rement on co l n devices mou ted on a se arate stru ture sp ced ≥ 3 m away from the prin ip l radiatin s rface of the tran former 36 Fig re 5 – Typical micro hone p sition for sou d me s rement on dry- yp tran formers without en los res 3

Fig re 6 – Prin iple radiatin s rface an pres rib d contour of dry- yp air-core re ctors 3

Fig re 7 – En ironmental cor ection, K 3

Ta le 1 – Test ac e tan e criteria 23 Ta le 2 – Ap roximate values of the average acou tic a sorption co ficient 2

INTERNATIONAL ELECTROTECHNICAL COMMISSION

Part 10: Determination of sound levels

1) Th Intern tio al Ele trote h ic l Commis io (IEC) is a worldwid org nizatio for sta d rdizatio c mprisin

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p te t rig ts IEC sh l n t b h ld resp nsible for id ntifyin a y or al su h p te t rig ts

International Stan ard IEC 6 0 6-10 has b en pre ared by IEC tec nical commite 14:

Power tran formers

This secon edition can els an re laces the first edition publ s ed in 2 01 an con titutes a

tec nical revision

This edition in lu es the fol owin sig ificant tec nical c an es with resp ct to the previou

edition:

– ad itional u eful definition introd ced;

– definition of distribution typ tran formers introd ced for the purp se this stan ard;

– new clau e for sou d level me s rement sp cification introd ced;

– req irement for 1/3 octave b n me s rements introd ced for tran formers other than

– stan ard me s rement distan e c an ed from 0,3 m to 1 m for tran formers other than

distribution typ tran formers;

– heig t of me s rement s rface is now cle rly defined to cou t from the reflectin plane;

– me s rement s rface formula u ified;

– cor ection criteria for inten ity method introd ced;

– rules for sou d me s rements on dry- yp re ctors introd ced;

– fig res revised;

– new informative test re ort templates introd ced (An ex B);

– IEC 6 0 6-10-1 (a pl cation g ide) revised in p ralel providin worthwhie information for

the u e of this stan ard

The text of this stan ard is b sed on the fol owin doc ments:

Ful information on the votin for the a proval of this stan ard can b fou d in the re ort on

votin in icated in the a ove ta le

This publcation has b en drafed in ac ordan e with the ISO/IEC Directives, Part 2

A l st of al p rts in the IEC 6 0 6 series, publ s ed u der the general title Power

tra sformers, can b fou d on the IEC we site

The commit e has decided that the contents of this publcation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "htp:/we store.iec.c " in the data

related to the sp cific publ cation At this date, the publ cation wi b

INTRODUCTION

One of man p rameters con idered when specifyin , desig in an placin tran formers,

re ctors an their as ociated co l n devices is the sou d level that the eq ipment is l k ly to

emit u der defined in-service con ition This p rt of IEC 6 0 6 provides the b sis for the

sp cification an test of sou d levels

This stan ard des rib s in a logical seq en e the lo din con ition , how to sp cify an to

test as wel as how to evaluate an re ort sou d levels for the eq ipment u der test A new

section for the sp cification of sou d levels has b en introd ced as Clau e 5

For the purp se of this stan ard, the definition “distribution typ tran formers” was

introd ced This reflects in u try’s ne d to maintain simpler an faster sou d me s rements

for this category of tran formers

The new req irement for re ortin 1/3-octave b n sp ctra for al sou d levels (in lu in the

b ckgrou d noise) on u its for in tal ation in s bstation reflects the more onerou con ition

imp sed by plan in authorities on the purc aser an also the improved fu ctional ty of

modern in trumentation

When the sou d inten ity method was introd ced in this stan ard l mited exp rien e was

avai a le Durin s bseq ent ye rs of o eratin this stan ard levels of exp rien e have

sig ificantly in re sed an neces ary c an es have b come evident The eq ivalen e of the

pres ure an the inten ity method has b en demon trated within certain test l mitation

The introd ction of new val dation criteria for the inten ity method recog ises these

l mitation The p rmis ible pres ure – inten ity in ex ∆L remain 8 dB however the

dif eren e b twe n me s red sou d pres ure level an re orted sou d inten ity level is

l mited to 4 dB

For the pres ure method the cor ection proced re for reflection has b en en an ed by

recommen in the a pl cation of freq en y de en ent K values derived by me s rement of

the reverb ration time of the test faci ty Where K is derived from a sorption co ficients the

ta le for the average a sorption co ficients has b en rational sed to re resent s rfaces lk ly

to b fou d in the workin en ironment

Walk-arou d proced re an p int by-p int proced re are eq al y a plca le The walk-arou d

proced re reflects the evolution of workin practice al owin more time ef icient

me s rements mainly on large u its For distribution typ tran formers an in sp cial

situation (he lth an safety) the p int by-p int proced re is more a pro riate

In order to mitigate ne r- ield ef ects the prefer ed me s rement distan e is set to 1 m with

ex e tion for distribution typ tran formers, smal test faci ties, situation with low

sig al- o-noise ratio an for he lth an safety where the distan e is maintained at 0,3 m

One sin le formula for the calc lation of the me s rement s rface are S has b en introd ced

b cau e the former complexity could only res lt in dif eren es alway smaler than 1 dB

Al fig res des ribin the me s rement s rface are have b en revised to b in ac ordan e

with the en elo in method for sou d p wer determination The heig t h is alway me s red

from the test faci ty flo r regardles of the heig t of the s p orts b ne th the test o ject

u les the test o ject is mou ted on a s p ort with a s f iciently large s rface actin as

reflectin plane

Ad itional fig res explain the proced re for the determination of the me s rement s rface

When u in this stan ard, it is recommen ed to freq ently refer to the cor esp n in

a pl cation g ide IEC 6 0 6-10-1:2 16 as it promotes u derstan in with imp rtant

b ckgrou d information an helpful detais IEC 6 0 6-10 an IEC 6 0 6-10-1 were revised

in p ral el by the same maintenan e te m res ltin in ful y al g ed doc ments

POWER TRANSFORMERS –

Part 10: Determination of sound levels

This Part of IEC 6 0 6 defines sou d pres ure an sou d inten ity me s rement method

from whic sou d p wer levels of tran formers, re ctors an their as ociated co l n devices

are determined

NOT For th p rp ses of this sta d rd, th term"tra sformer fre u ntly me ns "tra sformer or re ctor

The method are a pl ca le to tran formers, re ctors an their co l n devices – either fit ed

to or se arate from the tran former – as covered by the IEC 6 0 6 an IEC 613 8 series

This stan ard is primari y inten ed to a ply to me s rements made at the factory Con ition

on-site can b very dif erent b cau e of the proximity of o jects, in lu in other tran formers

Nevertheles , this stan ard is a pled to the extent p s ible for on-site me s rements

2 Normative referenc s

The folowin doc ments, in whole or in p rt, are normatively referen ed in this doc ment an

are in isp n a le for its a pl cation For dated referen es, only the edition cited a pl es For

u dated referen es, the latest edition of the referen ed doc ment (in lu in an

amen ments) a pl es

IEC 6 0 6-1:2 1 , Power tra sformers – Part 1: G en ral

IEC 6 0 6-8:19 7, Power tra sformers – Part 8: App licato guide

IEC 610 3:19 3, Ele ctro coustc – Instrume ts for th me sureme t of sound inte siy –

Me sureme ts wih p airs ofp re ssu re se nsin microp ho e s

IEC 616 2-1, Electro coustc – Sound le el meters – Part 1: Sp ecificato s

IEC 616 2-2, Electro coustc – Sound le el meters – Part 2: Patern e aluato tests

ISO 3 8 -2:2 0 , Acoustc – Me sureme nt of ro m acoustc p arameters – Part 2:

Re erb e rato tme in ordin ry ro m s

ISO 3 4 :2 10, Acoustc – D etermin to of sou nd p wer le e ls a d sound e ergy le vels of

su rface o e r a refle ctn pla e

ISO 9 14-1:19 3, Acoustc – Determin to of sound p ower le vels of n ise sources usin

sound inte nsiy – Part 1: Me asureme t at dis rete p oints

ISO 9 14-2:19 6, Acoustc – Determin to of sound p ower le els of n ise sources usin

sound inte nsiy – Part 2: Me sureme nt b y s a nin

ten times the logarithm to the b se 10 of the ratio of the s uare of the r.m.s sou d pres ure

to the s uare of the referen e sou d pres ure (p

p

lg

10

pp

comp nent of the sou d inten ity in the direction normal to a me s rement s rface

Note 1 to e try: By c n e tio , n rmal so n inte sity is c u te p sitiv if th e erg flow is dire te awa from

th test o je t a d n g tiv if th e erg flow is dire te towards th test o je t

3.5

normal sound intensity level

I

L

ten times the logarithm to the b se 10 of the ratio of the r.m.s normal sou d inten ity to the

referen e sou d inten ity (I = 1 × 10

–12

Wm–2

)

Note 1 to e try: It is e pres e in d cib ls, dB

0n

Ilg

10

II

3.6

direction flag

Dir

F

in ication for the direction of sou d energ flow, req ired for sou d inten ity b cau e of its

vector nature

Note 1 to e try: +1 for so n e erg flow awa from th test o je t, –1 for so n e erg flow towards th test

o je t

3.7

sound power

W

rate at whic airb rne sou d energ is radiated by a source

Note 1 to e try: It is e pres e in wats, W

3.8

sound power level

W

ten times the logarithm to the b se 10 of the ratio of a given r.m.s sou d p wer to the

referen e sou d p wer (W

lg

10

WW

3.9

total sound level

sou d level comprisin the whole freq en y ran e u der con ideration

Note 1 to e try: This le el is return d eith r dire tly b th me sureme t d vic or d riv d b lo arithmic

summatio of th so n le els of al in ivid al fre u n y b n s

3.10

principal radiating s rface

h p thetical s rface s r ou din the test o ject, as umed to b the s rface from whic sou d

is radiated

3.1

me s rement s rface

S

s rface en elo in the test o ject at the me s rement distan e from the prin ip l radiatin

s rface on whic the me s rement p th(s) or p ints are located

)

Note 1 to e try: It is e pres e in d cib ls, dB

0S

lg

10

SS

sou d level me s rement o tained by contin ou ly movin the micro hone(s) alon the

pres rib d contour(s) at con tant walkin sp ed as the device is me s rin a time averaged

an sp tialy averaged sou d level

Note 1 to e try: Test e uipme t ma re ord a digital a dio fie d rin th me surin pro e ure for p st

pro es in to d termin th n c s ary q a tities

3.16

point by-point procedure

sou d level me s rements o tained from a n mb r of dis rete micro hone p sition on the

pres rib d contour(s), eq al y sp ced an not more than 1 m a art

Note 1 to e try: Th sp tial a era e so n le elis th a era e of al th p int me sureme ts

cor ection that ac ou ts for the influen e of u desired sou d reflection from ro m

b u daries an /or reflectin o jects in the test ro m when sou d pres ure me s rements are

u ed

3.19

P-I index

∆L

dif eren e b twe n u cor ected sp tial y averaged sou d pres ure level an sp tial y

averaged sou d inten ity level

Note 1 to e try: A-weig te v lu s sh l b use

3.2

distribution type tran formers

tran formers for in tal ation other than in s bstation with rated p wer typicaly lower than

5 0 0 kVA

Note 1 to e try: This d finitio is ma e for th p rp se of this sta d rd

Note 2 to e try: Thisd finitio a ples to b th lq id-immerse a d dry- y e tra sformers

4 Sound power for dif erent loading conditions

There are thre comp nents of sou d p tential y contributin to the overal tran former sou d

• sou d p wer at no-lo d ex itation;

• sou d p wer of the co l n device;

• sou d p wer d e to lo d c r ent

The re resentation of the sou d p wer level of a tran former at a certain service con ition is

given by the logarithmic s m of the thre sou d p wer comp nents at this service con ition

For detai s se Clau e 13

4.2 Sound p wer at no-lo d ex itation

Sou d p wer d e to no-lo d ex itation has to b regarded for al typ s of tran former The

ex itation voltage s al b of sin soidal or practical y of sin soidal waveform an rated

freq en y The voltage s al b in ac ordan e with 1 5 of IEC 6 0 6-1:2 1 In the case of

re ctors a no-lo d con ition do s not exist sin e rated c r ent wi flow as so n as rated

voltage is a pl ed For more information on re ctor sou d testin se IEC 6 0 6-6

The u ual con ition for sou d p wer level determination of tran formers at no-lo d ex itation

refers to rated voltage at an u ta p d win in Other ex itation con ition may oc ur in

service le din to lower or hig er sou d p wer levels an mig t also b the con ition for a

g arante an if so s al b sp cified by the purc aser For tran formers desig ed to o erate

with varia le flu , the sou d p wer at no-lo d ex itation is stron ly imp cted by the ta pin

p sition The ta pin p sition for the sou d me s rement has therefore to b agre d b twe n

man facturer an purc aser d rin ten er stage

If a tran former is fit ed with re ctor- yp on-lo d ta -c an er eq ipment where the re ctor

may on certain ta -c an er p sition b p rmanently energized, the me s rements s al b

made with the tran former on a ta pin whic in olves this con ition an whic is also as

ne r to the prin ip l ta pin as p s ible

The selected test con ition s al b cle rly in icated in the test re ort

NOT D bias ma n tizatio of th c re c n c use a sig ific nt in re se in th me sure so n le els Its

prese c is in ic te b th e iste c of o d h rmo ics of th e citatio fre u n y in th so n sp ctrum a d this

c n b id ntifie b a n row b n a alysis Th D bias imp ct o n -lo d so n le el me sureme ts d rin

fa tory testin c n b pra tic ly elmin te b a o er e citatio ru for some min tes Wh n o er e citatio is n t

a pra tic l o tio , as in o -site me sureme ts, D bias elmin tio afer a tra sformer inrush e e t c n ta e

se eral h urs or e e d ys

4.3 Sound p wer of the co l n device(s)

The u ual con ition for sou d p wer level determination is to have al co l n devices

neces ary to o erate the tran former at its rated p wer ru nin

In case of a water co ln device, the water flow ne d not b maintained durin sou d level

testin

In case of varia le sp ed co ln devices (u ual y fan ) the sp ed d rin sou d level testin

has a sig ificant ef ect on the sou d p wer level The sp ed of the co l n device selected for

the sou d level me s rement s al b the sp ed neces ary to o erate the tran former at its

rated p wer u der the most onerou external co l n medium con ition

The selected test con ition s al b cle rly in icated in the test re ort

4.4 Sound p wer due to lo d c r ent

The main comp nent of the sou d p wer level d e to lo d c r ent, for most tran formers, is of

double the p wer freq en y

The mag itu e of the lo d c r ent sou d p wer level can b rou hly estimated by

Eq ation (5) an (6):

pr

IrWA,

SS

pr

IrWA,

SS

where

L

WA, r

is the estimated A-weig ted sou d p wer level of the tran former at rated c r ent

an rated freq en y at s ort circ it con ition;

is the referen e p wer (1 MVA)

For auto- ran formers an thre win in tran formers, the eq ivalent two-win in rated p wer

is u ed in te d of S

r, in ac ordan e with 3.2 of IEC 6 0 6-8:19 7

NOT 1 Th pre ictio s with Eq atio s (5) a d (6) are usu ly within ± dB of th me sure so n p wer le el

d e to rate lo d c re t

A g idel ne to estimate the sig ifican e of the sou d p wer due to lo d c r ent is given by

Eq ation (5) an (6) When the calc lated values are 10 dB or more b low the sou d p wer

level estimated at no-lo d ex itation, its contribution wi b negl gible an therefore ne d not

b tested, u les the purc aser has sp cified the test

NOT 2 Distrib tio ty e tra sformers usu ly d n t re uire c nsid ratio of so n p wer d e to lo d c re t

When this me s rement is req ired, one win in s al b s ort circ ited an the rated c r ent

at rated freq en y s al b injected into the other win in

Unles otherwise sp cified, the tests s al b car ied out with the ta -c an er (if an ) on the

prin ip l ta pin However, this ta p sition may not give the maximum sou d level in service

d e to variation of the mag etic stray field distribution in the win in s, the core an the

tank s ieldin elements

The selected test con ition s al b cle rly in icated in the test re ort

The sou d p wer level at a c r ent dif erent from the rated c r ent can b calc lated by

Eq ation (7):

rT

IrWA,IT

WA,

II

The eq ation is val d for c r ents in the ran e of 6 % to 13 % of rated c r ent It s al also

b a pled to calc late the sou d p wer level d e to rated lo d c r ent if, in case of test b y

In service, the direction of lo d flow an the p wer factor can imp ct the sou d p wer level

d e to a s p rp sition of the flu at no-lo d con ition an the stray flu p rtly enterin the

core This efect can ot b re lcated by factory testin

Sp cial tran formers s c as in u trial, SVC an HVDC con erter tran formers as wel as

sp cific typ s of re ctor exp rien e lo d c r ents with hig harmonic content an

s bseq ently prod ce sou d harmonic of hig er freq en y The injection of s c c r ents

req ires sp cial test eq ipment an test config ration whic u ual y are not avai a le for

tran former testin For re ctors s c tests are more common, se IEC 6 0 6-6 Where

testin is not p s ible, it is neces ary to agre on prediction of the sou d p wer level d e to

lo d c r ent in lu in its harmonic b sed up n calc lation For detai ed information se

4.2.5 an 7.6 as wel as An ex A of IEC 6 0 6-10-1:2 16

5 Sound lev l measurement specification

When sou d level me s rements are sp cified, the acou tic p rforman e of a tran former

s al b in icated by its A-weig ted sou d p wer level

In ex e tional cases, an average sou d pres ure level at a certain distan e is al owed to b

sp cified by the purc aser The determination of that pres ure level can either b o tained

from a me s rement of the sp tial y averaged sou d pres ure level at that distan e or derived

from the sou d p wer determined at a dif erent distan e

As a minimum, the sou d p wer level at no-lo d ex itation at rated voltage an freq en y on

an u ta p d win in s al b sp cified For varia le flu a plcation se 4.2

If the tran former is eq ip ed with a co ln device havin pumps an /or fan then the

co l n device’s sou d p wer level cor esp n in to the tran former’s rated p wer s al also

b sp cified Duties other than that req ired for rated p wer can b sp cified by the

purc aser

Alternatively, the combined s m of the tran former no-lo d ex itation an co l n device

sou d p wer level can b sp cified

If the calc lated sou d p wer level d e to lo d c r ent ac ordin Eq ation (5) an (6) is

con idered sig ificant by the purc aser, it is recommen ed to sp cify a me s rement of the

sou d p wer level d e to rated lo d c r ent in order to re ort the tran former sou d p wer

level as in service

NOT 1 Distrib tio ty e tra sformers usu ly d n t re uire c nsid ratio of so n p wer d e to lo d c re t

The purc aser may also sp cify a value for the s m of the sou d p wer levels

• at no-lo d ex itation,

• of the co ln device an

• d e to lo d c r ent,

al at the b fore mentioned ratin

Con ition other than those mentioned a ove, whic mig t b ter reflect the l k ly service

con ition, can b agre d for sou d me s rements

NOT 2 It is in th p rc aser interest to n tify th ma ufa turer o a y sp cial servic c n itio s, su h as th

prese c of h rmo ics a d/or d.c bias in th n twork for th imp ct to th in servic so n p wer le el to b

as es e

In case of phase segregated tran formers formin a thre -phase b nk the sou d level

Method u ed for the determination of sou d p wer levels can b either sou d pres ure or

sou d inten ity an are normal y c osen by the purc aser If not sp cified by the purc aser,

the man facturer s al c o se the method an it s al b stated in the ten er

Sou d me s rements for distribution typ tran formers s al provide the total sou d level as

p r definition 3.9 only, u les otherwise sp cified by the purc aser

NOT 3 This a ples also to re ctors with rate p wer lower th n 1 MV

Sou d me s rements for al other tran formers s al b exec ted with 1/3-octave b n

fi terin , u les an alternative b n width (octave-b n or nar ow-b n ) or a total sou d level

only is sp cified by the purc aser For more detai s on nar ow-b n me s rements se 5.4

an An ex A of IEC 6 0 6-10-1:2 16

Sou d me s rements on al tran formers an re ctors s al b exec ted with an active p rt

temp rature close to ambient test b y con ition , u les the purc aser has sp cified sou d

me s rements at close to service temp rature con ition (u ual y p rformed at the en of a

temp rature rise test

Unles otherwise sp cified by the purc aser, the c oice b twe n the u e of the walk-arou d

or the p int by-p int proced re s al b at the dis retion of the man facturer

NOT 4 Th difere c in me sure so n le el d e to th c ose meth d is n glgible b se o ma ifold

c mp riso s b t th walk-aro n pro e ure is les time c nsumin , esp cialy in th c se of larg u its

The p int by-p int proced re s al b a pled when safety con ideration dictate

The p int by-p int proced re is the logical c oice in situation where there are a smal

n mb r of me s rin p ints This normal y a pl es to distribution typ tran formers

6 Instrumentation, calibration and accurac

The avai a le freq en y resp n e of the me s rin in trument s al ran e from b low the

rated p wer freq en y to a ove the up er l mit of the h man e r ca a i ty of 2 kHz

In case of tran formers with a p wer freq en y lower than 2 Hz an when the me s rin

device is l mited in its lower freq en y en then it is ac e ta le to have double the p wer

freq en y as the lower freq en y en

The up er l mit for the actual me s rement s al b c osen in ac ordan e with the hig est

emit ed sig ificant freq en y, u ual y b low 10 kHz The selected freq en y ran e for

b ckgrou d noise me s rements an the test me s rement s al b the same

Sou d pres ure me s rements s al b made u in a typ 1 sou d level meter complyin

with IEC 616 2-1 an IEC 616 2-2 an cal brated in ac ordan e with 5.2 of ISO 3 4 :2 10

The sou d pres ure method of me s rements des rib d in this stan ard is b sed on

ISO 3 4 Me s rements made in conformity with this stan ard ten to res lt in stan ard

deviation of re rod cibi ty b twe n determination made in dif erent la oratories whic are

les than or eq al to 3 dB

Sou d inten ity me s rements s al b made u in a clas 1 sou d inten ity in trument

complyin with IEC 610 3 an cal brated in ac ordan e with 6.2 of ISO 9 14-1:19 3 The

freq en y ran e of the me s rin eq ipment s al b ada ted to the freq en y sp ctrum of

the test o ject, that is, an a pro riate micro hone sp cer s stem s al b c osen in order to

The sou d inten ity method of me s rements des rib d in this stan ard is b sed on

ISO 9 14-1 an ISO 9 14-2 Me s rements made in conformity with this stan ard ten to

res lt in stan ard deviation of re rod cibi ty betwe n determination made in diferent

la oratories whic are les than or eq al to 3 dB

The me s rin eq ipment s al b cal brated in ac ordan e with man facturer’s in tru tion

immediately b fore an af er the me s rement seq en e If the calbration c an es by more

than 0,3 dB, the me s rements s al b declared in al d an the test re e ted

Al me s rements s al b made u in the energetic average over the me s rement d ration

of the sou d q antity (pres ure or inten ity) Statisticaly derived sou d q antities s c as

p rcenties s al not b a pled

The fast resp n e in ication of the meter s al b u ed to identify an avoid me s rement

er ors d e to tran ient b ckgrou d noise

The sou d level me s rement is u ual y of man al o eration but the er ors introd ced by

varyin distan es wi ten to average out Their imp ct on the final me s rement is of les

sig ifican e than other acou tical factors Nevertheles , al efort s al b made to k e the

me s rement distan e as con tant as p s ible

NOT Markin th c nto r o th flo r or usin a sp c r b twe n micro h n a d tra sformer c n h lp to

a hie e th re uire me sureme t q alty

7 Principal radiating s rface

The definition of the prin ip l radiatin s rface de en s on the typ of co l n devices

employed an their p sition relative to the tran former or its en los re

The heig t of the prin ip l radiatin s rface is cou ted from the to of the test o ject to the

flo r of the test b y an in lu es the heig t of an s p ortin stru ture s c as whe ls,

p l ets, tran p rtation cars In case the s p ortin stru ture provides the acou tic pro erties

of a reflectin plane an exten s the strin contour (as sp cified in fol owin s bclau es) of

the test o ject by at le st twice the me s rin distan e, then the s p ortin stru ture s al b

con idered as the flo r

7.2 Transformers with or without cool ng device

The prin ip l radiatin s rface is the s rface o tained by the vertical projection of a strin

contour en ircln the eq ipment The projection ru s from the to of the tran former tank

cover (ex lu in protru ion s c as bu hin s, tur ets an other ac es ories situated a ove

the tank cover) or the to of the co l n device, whatever is hig er to the flo r of the test b y

The prin ip l radiatin s rface s al in lu e co l n devices located < 3 m away from the

tran former tank, tank stifeners an s c au i ary eq ipment as ca le b xes, ta -c an er

comp rtments, etc It s al ex lu e an co l n devices located ≥ 3 m away from the

con ervators, valves, control c bicles an other secon ary elements s al also b ex lu ed

as lon as they do not interfere with the pres rib d contour, se Fig res 1, 2 an 3 Where

protru ion interfere with the pres rib d contour, then these p rts are in lu ed within the

prin ip l radiatin s rface In cases where the heig ts of the tran former an the co l n

device deviate by more than a factor of two then the tran former an co l n plant sou d

levels s al b me s red se arately, even if the distan e b twe n b th p rts is les than 3 m

7.3 Transformers in enclos res with cool ng devices inside the enclos re

The prin ip l radiatin s rface is the s rface o tained by the vertical projection of a strin

protru ion s c as bu hin s, tur ets an other ac es ories situated a ove the en los re) to

the flo r of the test b y

7.4 Transformers in enclos res with cool ng devices outside the enclos re

The prin ip l radiatin s rface is the s rface o tained by the vertical projection of a strin

contour en ircl n the eq ipment The projection ru s from the to of the tran former

en los re (ex lu in protru ion s c as bu hin s, tur ets an other ac es ories situated

a ove the en los re) or the to of the co l n device, whatever is hig er to the flo r of the

test b y The prin ip l radiatin s rface s al in lu e co l n devices located < 3 m away from

the tran former en los re, au i ary eq ipment as ca le b xes, ta -c an er comp rtments,

etc It s al ex lu e co l n devices located ≥ 3 m away from the tran former en los re

Projection from protru ion s c as bu hin s, oi pip work an con ervators, valves, control

c bicles an other secon ary elements s al also b ex lu ed, se Fig res 1, 2 an 3 In

case of a tran former with sou d p nels, the sou d p nels are con idered as the en los re

In cases where the heig t of the tran former an the co l n device deviate by more than a

factor of two then the tran former an co l n plant sou d levels s al b me s red

se arately, even if the distan e b twe n b th p rts is les than 3 m

7.5 Cool n devices mou ted on a se arate structure where the distance betwe n the

two principal radiating s rfaces is ≥ 3 m

The prin ip l radiatin s rface is the s rface o tained by the vertical projection of a strin

framework, pip work, valves an other secon ary elements The vertical projection s al b

from the to of the co ler stru ture to the flo r of the test b y, se Fig re 4 For co l n

devices mou ted several meters a ove flo r level the pres rib d contours s al b c osen in

analog to dry- yp re ctors, refer to Clau e 8 an Fig re 6 g)

NOT In this c se th prescrib d c nto rs wi b at h lf of th h ig t of th su p rt stru ture a d at th mid

pla e of th c oln d vic

7.6 Dry- ype transformers

In case of dry- yp tran formers without en los re the prin ip l radiatin s rface is the

s rface o tained by the vertical projection of a strin contour en ircl n the dry- yp

tran former ex lu in protru ion s c as framework, external wirin an con ection an

at ac ed a p ratu not af ectin the sou d radiation The vertical projection s al b from the

to of the tran former stru ture to the flo r of the test b y, se Fig re 5 The prin ip l

radiatin s rface s al in lu e co l n devices atac ed to the tran former, if an

In case of dry- yp tran formers with en los re the prin ip l radiatin s rface is the s rface

o tained by the vertical projection of a strin contour en ircln the eq ipment The projection

ru s from the to of the tran former en los re, ex lu in protru ion s c as bu hin s,

tur ets an other ac es ories to the flo r of the test b y The prin ip l radiatin s rface s al

in lu e co l n devices, au i ary eq ipment as ca le b xes, ta -c an er comp rtments, etc

when at ac ed to the tran former en los re

7.7 Dry- ype air-core re ctors

The prin ip l radiatin s rface is the s rface o tained by the vertical projection of a strin

con ection an at ac ed a p ratu s c as ar esters or s rge ca acitors not af ectin the

sou d radiation The projection ru s from the to of the re ctor to the flo r of the test b y

The heig t of the prin ip l radiatin s rface is therefore the s m of the heig t of the s p ort

stru ture to the flo r of the test b y (h

) an the heig t of the re ctor coi (h

R) In case of a

stack d re ctor the heig t of the re ctor (h

R) is the total heig t of the re ctor stack, se

Fig re 6

For sin le phase re ctors or re ctor stacks not eq ip ed with sou d s ield , the strin

For re ctors eq ip ed with sou d s ield , the strin contour is the circ mferen e of the sou d

s ield

For thre -phase re ctors mou ted in a trian ular ar an ement the strin contour en elo s al

thre re ctor phase-coi s an is s own in Fig re 6 b)

For thre -phase re ctors mou ted side-by-side the strin contour en elo s al thre of the

re ctor phase-cois an is s own in Fig re 6 c)

8 Pre cribed c ntour

For distribution typ tran formers, where factories have smal test faci ties or when anec oic

c amb rs are u ed for sou d me s rements, the pres rib d contour s al b sp ced 0,3 m

away from the prin ip l radiatin s rface

For dry- yp tran formers without en los res, the pres rib d contour s al b sp ced 1 m

away from the prin ip l radiatin s rface for safety re son

For al other tran formers, the pres rib d contour s al b sp ced 1 m away from the prin ip l

radiatin s rface u les the fol owin con ition a ply, where the distan e may neces ari y

b red ced to 0,3 m:

• l mited sp ce in the test b y;

• low sig al- o-noise ratio in case of low-noise tran formers an /or hig b ckgrou d noise

NOT 1 A low sig al- o-n ise ratio is in ic te if th v ld tio criteria for th sele te test meth d c n ot b

met, se 1 2.4 a d 1 3.4

For me s rements made with forced air co l n devices in service, the pres rib d contour

s al b sp ced 2 m away from the prin ip l radiatin s rface to minimise the efects of air

turbulen es For dry- yp u its with an without en los re an with forced air co l n devices

in service, the pres rib d contour s al b sp ced 1 m away from the prin ip l radiatin

s rface as turbulen es in s c a pl cation are normaly l mited

NOT 2 Th le gth of th prescrib d c nto r c n eith r b me sure in th test b y or c lc late from a drawin

or C D mo el

For a p rtic lar test set up the one selected me s rement distan e a pl es arou d the entire

test object Dif erent me s rement distan es can a ply for dif erent test set ups as for

example a c an e from 1 m to 2 m, when fan are ru nin

NOT 3 Ba k ro n informatio for th sele tio of th me sureme t dista c s is giv n in 5.5 of

IEC 6 0 6-10-1:2 16

For tran formers an /or co l n devices with a heig t of < 2,5 m, the pres rib d contour s al

b on a horizontal plane at half the heig t For tran formers an /or co ln devices with a

heig t ≥ 2,5 m, two pres rib d contours s al b u ed whic are on horizontal planes at on

e-third an two- hird of the heig t For safety re son , alternative heig ts can b selected

For dry- yp air-core re ctors the pres rib d contour s al b sp ced 2 m away from the

prin ip l radiatin s rface, however for field me s rements it may b neces ary for safety

re son to in re se the sp cin

De en in on the heig t of the s p ort stru ture an the heig t of the re ctor coi /stack one

or two pres rib d contours on horizontal planes s al b u ed:

For the walk-arou d proced re, the micro hone s al b moved with a con tant sp ed of

maximum 1 m/s on the pres rib d contour(s) arou d the test o ject At the given walkin

sp ed, the sampl n rate of modern integratin sou d level meters is alway s ficient for

ac urate sp tial averagin up to a resolution of 1/3-octave The sp tial y averaged sou d

level over the me s rement d ration s al b recorded together with the active me s rement

d ration in the test re ort

NOT Th “S A T – S OP” a d “PA S ” fu ctio s of su h so n le el meters c n b use to simplfy th

me surin pro e ure, ie to n g tiate o sta les a d/or to c a g b twe n prescrib d c nto rs

For the p int by-p int proced re, the micro hone p sition s al b on the pres rib d

contour(s), eq al y sp ced an not more than 1 m a art (se dimen ion D in Fig res 1 to 5)

There s al b a minimum of eig t micro hone p sition alon e c contour The me s rin

d ration s al b a minimum of thre secon s an b practical y the same d ration at e c

p sition

It can b neces ary to modify some me s rin p sition for certain test o jects for safety

re son , for example, in the case of tran formers with horizontal hig voltage bu hin s where

p rt of the pres rib d contour(s) may b confined to the safe zone

is the len th in metres of the pres rib d contour;

x is the me s rement distan e in meters from the prin ip l radiatin s rface to the

pres rib d contour

NOT 1 Eq atio (8) a ples for th me surin dista c s of 0,3 m, 1 m, 2 m b t also a y oth r me surin

where

R is the distan e in meters from the ge metrical centre of the tran former / co l n device

to the con idered location in the far- ield

NOT Eq atio (9) is also a plc ble for th c lc latio of th so n pres ure le el from th so n p wer le el

For furth r informatio o far-ield c lc latio s, se Cla se 14

11 Sound measurement

1 1 Test conditions

1 1.1 Placement of test object

The fol owin con ition s al b met in order to satisfy the as umption for the en elo in

method ac ordin to ISO 3 4 for sou d pres ure me s rements an ISO 9 14-2:19 6 for

sou d inten ity me s rements

An en ironment havin an a proximately fre field over a reflectin plane s al b u ed The

reflectin plane s al prefera ly have an acou tic a sorption co ficient of les than 0,1 over

the freq en y ran e of interest, se Clau e 6 This req irement is u ual y fulfi ed when in o r

me s rements are made over con rete, resin, ste l or hard ti e flo rin or when outdo r

me s rements are made over con rete, se led asphalt, san or stone s rfaces The

reflectin plane s al b larger than the are within the pres rib d contour

Care s al b ta en to en ure that the reflectin plane (s p ortin s rface) do s not radiate

an a precia le sou d p wer d e to vibration

It is ac e ta le to close ga s b twe n test ro m flo r an tran former tank b t om with sou d

a sorbin material whic a p ar as a res lt of the test set up only an whic do not a p ar in

service However, an other sou d a sorb nt materials placed on the flo r within the are of

the pres rib d contour s al b removed d rin test

The me s rement s rface s al l e within a sou d field es ential y u disturb d by reflection

from ne rby o jects an the en ironment b u daries Reflectin o jects s al therefore b

removed as far as p s ible from the test o ject Placin the test o ject not in p ral el to

reflectin wals an as far away as p s ible from those wi help to minimise reflection For

more information se also 6.3 of IEC 6 0 6-10-1:2 16 The u e of sou d a sorbin p nels

outside the are of the pres rib d contour wi also improve the test en ironment

The en elo in method is not a pl ca le for me s rements in ide reverb rant tran former

cel s or en los res

1 1.2 Test energisation options

The fol owin o tion for tran former energisation are avaia le an s al b a pl ed as

sp cified an agre d up n with the eq ipment u der test at ambient temp rature, se

Clau e 4

a) tran former at no-lo d ex itation without co l n device(s);

b) tran former at no-lo d ex itation with co l n device(s);

c) tran former at lo d c r ent in s ort circ it con ition without co l n device(s);

d) tran former at lo d c r ent in s ort circ it con ition with co l n device(s);

e) co lng device(s) only

If the me s rement of a sp cific combination is not sp cified to b actualy me s red then it

is ac e ta le to derive the sou d p wer level of this sp cific combination by logarithmic

NOT 1 It is esta lsh d pra tic , to me sure th in ivid al so n le el c mp n nts d rin ty e test h we er th

su se u nt ro tin tests o id ntic l u its are g n raly p rforme with ut c olers mo nte Optio a) a d c) are

th n me sure (if sp cifie ) a d th c oler so n le el from th ty e test is a d d

NOT 2 Co fig ratio c) c n b a ple o ly if n sig ific nt lo al temp rature rise is e p cte in a y sectio of

th win in ar a g me t

If a sou d level test is sp cified to b p rformed at a temp rature close to service

temp rature then the to -lq id temp rature is to b me s red an noted in the test re ort

NOT 3 A minimum of time sp nt for a so n le el me sureme t a oids c a g s in th so n le el c use b

c a g s in tra sformer temp rature

NOT 4 Th D bias imp ct o n -lo d so n le el me sureme ts d rin fa tory testin c n b pra tic ly

elmin te b a o er-e citatio ru for some min tes, se also 4.2

1 1.3 Test a pl cation detai s

The test method (pres ure method, inten ity method), test proced re (walk-arou d proced re,

p int by-p int proced re), fi terin b n width an tran former temp rature (ambient or close

to service) s al b as sp cified, se Clau e 5 If nothin is sp cified by the purc aser then

the me s rement method an proced res wi b selected by the man facturer from the

avai a le o tion within this stan ard in order to me s re the req ired sou d levels

1 1.4 Prevai ng ambient conditions

For the integrity of b th method des rib d b low a ste d -state b ckgrou d noise level

throu hout the sou d level me s rement s al b maintained

NOT If th b c gro n n ise is fre u ntly disturb d th n it c n b prefera le to use th p intb -p int

pro e ure

Outdo r me s rements s al not b made u der extreme mete rological con ition , for

example, in the presen e of temp rature gradients, stron win sp ed , an typ of

precipitation, s ow ac umulation an at hig h midity for me s rements at distan es larger

than 10 m

1 2 Sound pres ure method

1 2.1 General

Sou d pres ure me s rements arou d the test o ject are afected by the test environment

an the fol owin cor ection s al b made, as a pl ca le:

• cor ection for ste d -state b ckgrou d noise;

• cor ection for sou d reflection by factor K

NOT So n field efe ts close to th test o je t (n ar field efe ts) c n imp ct so n pres ure me sureme ts at

a me surin dista c of 0,3 m Th y te d to in re se th me sure so n pres ure le el in th ra g of 0,5 dB to

1,5 dB

1 2.2 Test procedure

The intention of this test is to re ort the total sp tialy averaged A-weig ted sou d pres ure

level for e c energisation o tion ac omp nied with a sin le sp tial y averaged freq en y

sp ctrum (where a plca le)

The same test proced re (either walk-arou d proced re or p int by-p int proced re) a pl es

for b th b ckgrou d noise me s rements an test me s rements

The micro hone(s) p sition as des rib d in Clau e 9 a ply for b th b ckgrou d noise

For the p int by-p int proced re, when the n mb r of me s rin p sition ex e d 10, it is

p rmis ible to me s re the b ckgrou d noise level at only 10 p sition eq al y distributed

arou d the test o ject

A total sp tial y averaged b ckgrou d noise level (se definition 3.17) an the cor esp n in

freq en y sp ctrum s al b recorded immediately b fore an afer e c test me s rement

seq en e Where the p int by-p int proced re is a pled, it is p s ible to determine the

freq en y sp ctrum from the average of the sp ctra me s red at al in ivid al micro hone

p sition or by an ad itional walk-arou d me s rement If the lat er is a pled this s al b

cle rly mentioned in the test re ort

If the b ckgrou d noise level is at le st 10 dB b low that of the test o ject then the

b ckgrou d noise can b me s red at only one location on the pres rib d contour an a

b ckgrou d noise cor ection is not neces ary

A total sp tial y averaged A-weig ted sou d pres ure level together with the cor esp n in

freq en y sp ctrum s al b recorded for either the walk-arou d proced re or the p int

by-p int proced re as a pro riate For the p int by-p int proced re the purc aser can

ad itionaly req est in ivid al total A-weig ted sou d pres ure levels to b recorded for e c

micro hone p sition Where the p int by-p int proced re is sp cified, it is p s ible to

determine the freq en y sp ctrum by ta in the average of the sp ctra ta en at al in ivid al

micro hone p sition or by an ad itional walk-arou d me s rement If the later is a pl ed

this s al b cle rly mentioned in the test re ort

1 2.3 Calc lation of the sp tial y averaged soun pres ure level

For the walk-arou d proced re the in trument wi automatical y provide the sp tial y

averaged me s rement data In case of the p int by-p int proced re the sp tial y averaged

me s rement data may also be derived automatical y by the in trument via p st proces in or

it has to b calc lated as des rib d b low When req ired to re ort p int by-p int

me s rements for e c micro hone p sition it may b neces ary to derive the total sp tial y

averaged sou d pres ure level by calc lation The total sp tialy averaged A-weig ted sou d

pres ure level for the test me s rement,

pA 0

L , s al then b calc lated from the total

A-weig ted sou d pres ure levels,

1i

1,0

0pA

pA i

101

1

1,0

101

lg

10

ibgA

bAi

(1 )

where

b A i

L is the me s red total A-weig ted b ckgrou d noise level at the i

th

micro hone p sition

The same calc lation proced re a pl es for e c in ivid al b n ν of the freq en y sp ctrum

res ltin in sp tialy averaged A-weig ted sou d pres ure levels

ν

pA0L

an sp tial y averaged

b ckgrou d noise levels

ν

b AL

1 2.4 Val dation of test me s rements with respect to background noise

For practical purp ses the valdation proces des rib d b low is b sed on the total sp tial y

averaged A-weighted sou d pres ure level

L , the test me s rement s al b declared in ald an the test re e ted

However, in cases where the test me s rement me ts the g arante , cor ection for

b ckgrou d noise is not req ired In this case the test is declared a p s

If the gre ter of the two b ckgrou d noise levels

b A

L is les than 3 dB b low the A-weig ted

sou d pres ure level of the test me s rement

pA 0

L , the test me s rement s al b declared

in al d an the test re e ted However, in cases where the test me s rement me ts the

g arante , cor ection for b ckgrou d noise is not req ired In this case the test is declared a

p s

Whi st this stan ard p rmits smal diferen es b twe n b ckgrou d noise an test

me s rement sou d levels, every efort s ould b made to o tain a diferen e of a out 6 dB

When the dif eren e b comes les than 3 dB, the u e of alternative me s rement method

may b con idered (se 1 3 an An ex A)

The a ove req irements are s mmarized in Ta le 1

Ta le 1 – Test ac e tance criteria

bgApA0

hig er

bgAbgA

me ts th g ara te Core tio for b c gro n n ise is n t

re uire in this c se a d th test is d clare a p s

1 2.5 Calc lation of environmental cor ection K

1 2.5.1 General

The en ironmental cor ection K , expres ed in dB, ac ou ts for the influen e of u desired

sou d reflection from ro m b u daries an /or reflectin o jects within the test are The

mag itu e of K de en s prin ip l y on the ratio of the sou d a sorption are of the test ro m,

by the location of the test o ject in the test ro m an K do s not cor ect for me s rements

4

1lg

10

(12)

The en ironmental cor ection factor K s al prefera ly b determined by me s rement

tec niq es However, for the purp se of this stan ard estimation for K is al owed by u e of

a sorption co f icients

For a test ro m to b satisfactory, the ratio A/S s al b ≥ 1 with a cor esp n in value for the

en ironmental cor ection factor K ≤ 7 dB However, if the ratio A/S is ≤ 2,5 with a

cor esp n in value for the en ironmental cor ection factor K ≥ 4,1 dB, then the determination

of K s al b b sed on acou tical me s rements

Where con ition are close to fre - ield, i.e es ential y u disturb d by reflection from ne rby

o jects an the en ironment b u daries, as sometimes ac ieved for outdo r me s rements,

then the value for K would ten to zero an no en ironmental cor ection is neces ary

1 2.5.2 Determination of K based on me s rement of the reverberation time

The reverb ration time of the test ro m is determined by ex itin the test ro m with

bro db n sou d or impulsive sou d an me s rin the decayin resp n e as A-weig ted

bro db n or more precisely for in ivid al b n s of the freq en y sp ctrum, as p r

ISO 3 8 -2:2 0

The value of A is given in s uare metres by Sa ine’s Eq ation (13):

where

V is the volume of the test ro m in c bic metres;

T is the reverb ration time of the test ro m in secon s

Eq ation (13) a pl es for the bro db n A weig ted resp n e an also for in ivid al b n s of

the freq en y sp ctrum when K is determined in ivid aly for the freq en y b n s

Whi st the a pl cation of K for the in ivid al freq en y b n s wi provide a more ac urate

cor ection, for practical purp ses it is p s ible to a ply only one K factor for the whole

sp ctrum

Ide l y, the determination of K is p rformed b fore e c me s rement with test la eq ipment

an test o jects in place Becau e this is of en not practical the determination of K can also

b done on e as referen e with the test la empty of al u neces ary eq ipment

NOT 1 K d termin d withth test la empty of al u n c s ary e uipme t results in th lowest p s ible v lu

NOT 2 Th d termin tio of th so n a sorptio are A with al u n c s ary e uipme t remo e from th test

la c n prefera ly b pro id d b a in e e d nt a e c a d th c rtific te b use to d mo strate th

d termin tio of K to th p rc aser o re u st

1 2.5.3 Determination of K based on a sorption co f icients

Wals a d c i n s within a ire ularly sh p d ma hin ry ro m or pro u tio

fa i ty, test b y wals a d c i n with ut a o stic d mpin material

0,2

Wals a d c i n s with a o stic d mpin material of u to 2 cm thic n s 0,3

Wals a d c i n s with a o stic d mpin material of more th n 2 cm thic n s 0,5

The entire s rface of the volume of the test ro m s al matc the s m of the p rtial s rfaces

S

Vi

in Eq ation (14), in lu in wal s, cei n , flo r an o en gates

The a ove mentioned calc lation for the sou d a sorption are A ac ordin Eq ation (14)

s al b in lu ed in the test re ort

The determination of K with this method a ples as cor ection for b th the total A-weig ted

sou d pres ure level an for in ivid al b n s of the freq en y sp ctrum

1 2.5.4 Alternative method for the estimation of K

Alternatively, K can b determined by me s rin , in the test faci ty, the a p rent sou d

p wer level of a referen e sou d source The referen e sou d source wi have b en

previou ly calbrated in a fre field over a reflectin plane It then can b writen

K = L

Wm– L

is the sou d p wer level of the referen e sou d source, determined ac ordin to

Clau es 7 an 8 of ISO 3 4 :2 10 not ac ou tin for reflected sou d;

L

Wr

is the me s red a p rent sou d p wer level of the referen e sou d source meas red in

the test faci ty ac ou tin for reflected sou d (L

Wr

> L

Wm)

The determination of K with this method a ples as cor ection for b th the total A-weig ted

sou d pres ure level an for in ivid al b n s of the freq en y sp ctrum, as lon as the

sou d p wer of the referen e source was estimated u in freq en y selective tec niq es

NOT This meth d is ofe uti se at smal test fa i ties

LL

,0

The same calc lation proced re a pl es for in ivid al b n s ν of the freq en y sp ctrum

res ltin in cor ected sp tial y averaged A-weig ted sou d pres ure levels

ν

pAL

al refer to the lower of the two total sp tial y averaged A-weig ted

b ckgrou d noise levels

b A

If Eq ation (16) is a pled for in ivid al freq en y ban s ν then the total sou d pres ure level

is the logarithmic s m of the cor ected sou d pres ure level of the in ivid al freq en y

b n s

In circ mstan es when a b ckgrou d noise level in a sp cific b n

ν

b AL

is gre ter than the

test me s rement sou d pres ure level

ν

pA0L

in the same b n , then the cor esp n in

ν

pAL

1 3 Sou d inten ity method

1 3.1 General

The sou d inten ity method is, within certain l mits, in en itive to ste d -state b ckgrou d

noise an reflection Therefore cor ection ne d not b a pl ed For more information se

also IEC 6 0 6-10-1:2 16

It is in erent to the sou d inten ity method that the me s rement s rface an therefore the

me s rement p th s al completely en ircle the test o ject This is b cau e sou d inten ity is

a vector q antity

Where tank wal s are p rtial y covered by p nels, the inten ity method is not a pl ca le

b cau e the inten ity level me s red at the micro hone p sition wi not b re resentative to

the complete tran former s rface For more information se 6.5 of IEC 6 0 6-10-1:2 16

1 3.2 Test procedure

Both the normal sou d inten ity level an the sou d pres ure level s al b recorded for e c

me s rement

The micro hone sp cer within the inten ity pro e s al b selected to cover the neces ary

sou d sp ctrum to b me s red, otherwise the lower or up er freq en ies wi not cor ectly

b ta en into ac ou t an er ors wi b introd ced Diferent micro hone sp cers may ne d

to b u ed for the variou energisation o tion , se 1 1.2

The sou d inten ity pro e (micro hone p ir) p sition as des rib d in Clau e 9 a ply for the

me s rements As the pro e has directivity an p larity, it is es ential to maintain the axis of

the pro e normal an with its cor ect direction to the me s rement s rface

The intention of this test is to re ort the total sp tial y averaged A-weig ted normal sou d

inten ity an sou d pres ure level for e c energisation o tion ac omp nied with a sin le

sp tial y averaged freq en y sp ctrum (where a pl ca le)

The sp cified test proced re s al b a pl ed for the me s rement (walk-arou d proced re or

p int by-p int proced re)

A total sp tial y averaged A-weig ted normal sou d inten ity an sou d pres ure level

together with the cor esp n in freq en y sp ctrum s al b recorded for either the wal

k-arou d proced re or the p int by-p int proced re as a pro riate For the p int by-p int

proced re the purc aser can ad itional y req est in ivid al total A-weig ted normal sou d

inten ity an sou d pres ure levels to b recorded for e c micro hone p sition Where the

p int by-p int proced re is sp cified, it is p s ible to determine the freq en y sp ctrum by

ta in the average of the sp ctra ta en at al in ivid al micro hone p sition or by an

ad itional walk-arou d me s rement If the later is a pled this s al b cle rly mentioned in

the test re ort

1 3.3 Calc lation of average normal sound intensity and sound pres ure level

For the walk-arou d proced re the in trument wi automatical y provide the sp tial y

averaged me s rement data (normal inten ity level

L ) In case of the p int by-p int proced re the sp tial y averaged

me s rement data may also b derived automatical y by the in trument, via p st proces in

or it has to b calc lated as des rib d b low When req ired to re ort p int by-p int

me s rements for e c micro hone p sition it may b neces ary to derive the total sp tial y

averaged normal sou d inten ity an sou d pres ure level by calc lation The total sp tial y

averaged A-weig ted normal sou d inten ity level

IA 0

A-weig ted normal sou d inten ity levels

1

10

Dir iIA0

IAi

101

1

10

Dir iDir

IA i

101

the sou d pres ure levels

pA i

L , me s red at the in ivid al micro hone p sition u in

Eq ation (10)

The same calc lation proced re a pl es for in ivid al b n s ν of the freq en y sp ctrum

res ltin in sp tial y averaged A-weig ted normal sou d inten ity levels

ν

IA0L

ν

1 3.4 Me s rement val dation

Where there is a notice ble c an e in b ckgrou d noise d rin a me s rement the

me s rement s al b rejected

For practical purp ses the val dation proces des rib d b low is b sed on the me s red total

sp tial y averaged A-weig ted normal sou d inten ity an sou d pres ure levels,

IA0

pA0

L resp ctively Examination of in ivid al b n s of the freq en y sp ctrum is not req ired

The criterion for ju gin the ac e ta i ty of the test en ironment an the ac e ta i ty of the

ste d -state b ckgrou d noise is the P-I in ex as p r definition 3.19 an is given by

Eq ation (19):

IA0pA0LL

If ∆L > 8 dB, the me s rement s al b declared in al d

If 4 dB < ∆L ≤ 8 dB, the me s rement s al b ac e ted with a cor ection a pl ed, se 1 3.5

If ∆L ≤ 4 dB, the me s rement is vald without cor ection

NOT If ∆ > 8 dB, th re-ara g me t of th test setu , a altern tiv me surin dista c or a altern tiv

me sureme t meth d (so n pres ure meth d, n r ow-b n me sureme t, time-sy c ro o s me sureme t c n

b c nsid re Se also An e A

If the direction flag for the total sp tialy averaged normal sou d inten ity level

Dir

-1, this in icates either the overal energ flow b in toward the test o ject or an er one u

me s rement an the test is declared in ald

Where the direction flag for the sp tial y averaged normal sou d inten ity level of an

in ivid al b n of the freq en y sp ctrum b comes -1, this in icates the net energ flow in

that freq en y b n b in toward the test o ject This oc urs when the radiated sou d from

NOT Th PI-in e of in ivid al b n s fre u ntly wi e c e th p rmis ible v lu of 8 dB for th o eral PI

-in e This is c nsiste t with th me surin prin iple a d usu ly in ic tes a smal so n p wer in olv d

Where the direction flag for an in ivid al b n ν b comes -1, the cor ected sou d inten ity

either the cor ected total sp tial y averaged A-weig ted sou d pres ure level,

10

SS

L

pAWA

(2 )

0lg10

SS

L

IAWA

The same calc lation proced re a pl es for in ivid al b n s ν of the freq en y sp ctrum

res ltin in A-weig ted sou d p wer levels

or ν

IAL

ta en as zero are ir elevant an

con eq ently set to zero

13 Logarithmic addition and subtraction of individual s und levels

There are situation where it is neces ary to ad or s btract sou d levels Su h situation are

• combination of sou d levels for diferent lo din con ition ;

• combination of sou d levels for in ivid al b n s of the freq en y sp ctrum for dif erent

lo din con ition ;

• s mmation of in ivid al b n sou d levels to a total sou d level;

• s mmation of inten ity levels when it was neces ary to u e diferent sp cers to cover the

entire freq en y ran e of a sp cific me s rement

The eq ation given in this clau e a ply eq al y to the sou d level q antities of pres ure,

inten ity an p wer For sou d pres ure an for sou d inten ity it is neces ary that in ivid al

comp nents refer to the same me s rin p int or pres rib d contour For sou d inten ity it is

also neces ary that the orientation of the me s rin pro e is identical for the in ivid al

L

L

1,01

,01

,0

s um

10

10

10lg

10

21

+++

×

=

(2 )

Eq ation (2 ) is u ed for al sou d levels determined by the pres ure method in lu in

freq en y b n s an for total sou d levels determined by the inten ity method

Eq ation (2 ) an (2 ) a ply for the ad ition of sou d levels of dif erent sources or b n s

with a direction flag as for in ivid al b n s of sou d levels determined by the inten ity

method:

n2

1

1,0

nDir1

,0

Dir21

,0

Dir

s um

10

L

FF

1

1,0

nDir1

,0

Dir21

,0

Dir

s umDir

10

10

10

LL

L

FF

FSign

th

direction flag of the sou d levels L

1, L

2, L

When the purc aser sp cification req ires the sou d pres ure of the eq ipment at a certain

distan e to b q oted the fol owin a pl es

As an a proximate calc lation, as umin a p int source an free- ield con ition over a

reflectin plane, the sou d pres ure level,

pR

L , at a distan e R in metres from the

ge metrical centre of the source is given by Eq ation (2 ):

0h

WpR

lg

10

SS

is the sou d p wer level

For a more ac urate value, factors s c as directional c aracteristic , reflection , s re nin

n merical tec niq es may b req ired These are normaly not avai a le to the tran former

man facturer

15 Pre entation of results

The re ort s al in lu e al the fol owin information:

a) name of man facturer an place of man facture an test;

b) date of tests;

c) des ription of the test o ject givin its serial n mb r, rated p wer, rated voltage,

freq en y, ta -p sition for sou d me s rements d e to lo d;

d) g arante d sou d level an the lo din an me s rement con ition again t whic this

g arante d level is demon trated;

e) to -l q id temp rature in case where sou d level me s rements are p rformed at

temp rature close to service temp rature;

f referen e to this me s rement stan ard IEC 6 0 6-10;

g) sou d p wer level determination method an proced re u ed;

h) identification of sou d me s rin eq ipment an calbration verification in lu in serial

n mb rs of the in truments, micro hone(s) an cal bration source;

i) dimen ioned sk tc of the test o ject an the me s rin p sition ;

j) test con ition for e c test config ration in lu in voltage, c r ent, ta p sition, co l n

devices u ed an noise mitigation fe tures employed d rin test;

k) len th of the me s rement distan e, the pres rib d contour(s), the heig t of the test

o ject an the calc lated me s rement s rface are ;

l) name of the test en ine r an witnes es where neces ary;

m) sig ature of the p rson resp n ible for testin

When the sou d pres ure method is u ed, the fol owin information s al b in lu ed:

n) p int by-p int proced re: the total A-weig ted sou d pres ure level of the b ckgrou d

noise at e c b ckgrou d noise me s rin p sition an , where a pl ca le, a sp tial y

averaged freq en y sp ctrum immediately b fore an immediately afer the me s rement

seq en e;

o) walk-arou d proced re: the total sp tial y averaged A-weig ted sou d pres ure level of

the b ckgrou d noise an , where a pl ca le, a sp tial y averaged freq en y sp ctrum

immediately b fore an immediately afer the me s rement seq en e;

p) p int by-p int proced re: the total A-weig ted sou d pres ure level for e c me s rin

p sition, the total sp tial y averaged A-weig ted sou d pres ure level

an , where a plca le, a sp tial y averaged freq en y sp ctrum for e c of the p rformed

lo din con ition ;

r) the value of the en ironmental cor ection K, either bro db n or freq en y b n sp cific;

s) when the en ironmental cor ection K is derived by calc lation from a sorption co ficients,

the calc lation of the sou d a sorption are A; when the en ironmental cor ection K is

b sed on me s rements of the sou d a sorption are A, the referen e to the certificate of

the in e en ent agen y whic made the me s rements; when the en ironmental

cor ection K is derived by uti sation of a referen e sou d source, the referen e to the

t cor ected total sp tial y averaged A-weig ted sou d pres ure level,

pAL

L , for e c of the p rformed lo din con ition ;

v) s mmation of the derived sou d p wer levels for the lo din combination to b

g arante d, only at this final stage to b rou ded to the ne rest integer

When the sou d inten ity method is u ed, the folowin information s al be in lu ed:

w) p int by-p int proced re: the total A-weig ted sou d pres ure an inten ity level with its

direction flag

Dir

F for e c me s rin p sition, the total sp tial y averaged A-weig ted

sou d pres ure an inten ity level

a pl ca le, a sp tialy averaged freq en y sp ctra of the sou d pres ure an inten ity

level with its flag for e c of the p rformed lo din con ition ;

sp tial y averaged freq en y sp ctra of the sou d pres ure an inten ity level with its

flag for e c of the p rformed lo din con ition ;

y) value of ∆L for e c of the p rformed lo din con ition ;

z) cor ected total sp tial y averaged A-weig ted normal sou d inten ity level

IA

the p rformed lo din con ition ;

a1) total A-weig ted sou d p wer level, L

WA

an , where a plca le, a freq en y sp ctrum

ν

WA

L , with its direction flag for e c of the p rformed lo din con ition ;

b1) s mmation of the derived sou d p wer levels for the lo din combination to b

g arante d, only at this final stage to b rou ded to the ne rest integer

NOT A ty ic l form for th prese tatio of results is giv n in An e B

3 Prin ip l ra iatin surfa e

D Micro h n sp cin (if a plc ble)

1 Horizo talforc d air c oln 5 Ca le b x 9 Vertic l forc d air c oln

surfa e; th larg r of h1 a dh2

x Me sureme t dista c

Fig re 2 – Typical micro hone path / p sitions for sou d me s rement on transformers

having cool ng devices mou ted either directly on the tank or on a se arate stru ture

1 Prin ip l ra iatin surfa e 5 Su p rt stru ture su has wh els, p lets, tra sp rtatio c r

2 Prescrib d c nto r D Micro h n sp cin (if a plc ble)

3 Tra sformer ta k h Heig t of th prin ip l ra iatin surfa e; th larg r of h1 a d h2

IEC

1 Vertic l forc d air c oln 5 Horizo tal b u d ries of prin ip l ra iatin surfa e

2 Prin ip l ra iatin surfa e 6 Vertic l b u d ries of prin ip l ra iatin surfa e

3 Prescrib d c nto r D Micro h n sp cin (if a plc ble)

4 Horizo talforc d air c oln h Heig t of th prin ip l ra iatin surfa e

1 Prin ip l ra iatin surfa e

2 Prescrib d c nto r

h Heig t of c re with framework

D Micro h n sp cin (if a plc ble)

2

IEC

2 1