IEC_60551-1987_scan.pdf

NORME INTERNATIONALECEINTERNATIONAL STANDARDIEC551Deuxieme editionSecond editionCommission Electrotechnique Internationale1987International Electrotechnical CommissionMeAyHapoAHan OneKTpoTexHnyeckaa HOMHCCHADetermination des niveaux de bruit des transformateurset des bobines dinductanceDetermination of transformer and reactor sound levelsTEdCE1987 Droits de reproduction reserves-Copyright-all rights reservedVoL.8Darte de cette publcaton ne peut tre reprodute n utlisee sous quelqueNo part ol this publicaton may be reproduced or utzed n any form or by any means.ue ce soit et par aucun procede.electronique ou mecanique.y compns iaelectronic or mechanical.includng photocooyng and microfim.wthout permssionet les.sans Iaccord eont de fediteur.wntng from the publsher.Bueau Central de la Commission Electrotechnique Internationale 3.rue de Varembe Geneve.SuisseCode prix 25Price code551IEC1987CONTENTSPageFOREWORD5PREFACE.5Clause1.Scope.72.Definitions.73.Instruments.94.Conditions for measurement.95.Measurement of sound pressure levels.116.Calculation of surface sound pressure level and sound power level.197.Presentation of results.23FIGURES.28APPENDIX A-Test environment qualification procedure.3500099422534551iEC 1987-5-INTERNATIONAL ELECTROTECHNICAL COMMISSIONDETERMINATION OF TRANSFORMERAND REACTOR SOUND LEVELSFOREWORD1)The formal decisions or agreements of the IEC on technical matters,prepared by Technical Committees on which all the NationalCommittees having a special interest therein are represented,express,as nearly as possible,an international consensus of opinionon the subjects dealt with.2)They have the form of recommendations for international use and they are accepted by the National Committees in thatsense.3)In order to promote international unification,the IEC expresses the wish that all National Committees should adopt the text ofthe IEC recommendation for their national rules in so far as national conditions will permit.Any divergence between the IECrecommendation and the correspon.ding national rules should,as far as possible,be clearly indicated in the latter.PREFACEThis standard has been prepared by IEC Technical Committee No.14:Power transformers.The text of this standard is based on the following documents:Six Months RuleReport on VotingTwo MonthsProcedureReports on Voting14(CO)5814(CO)6614(CO)6714(CO)6914(CO)6814(CO)70Full information on the voting for the approval of this standard can be found in the Voting Reportsindicated in the above table.The following IEC publications are quoted in this standard:Publications Nos.76:Power transformers.76-1(1976):Part 1:General.289(1968):Reactors.651(1979):Sound level meters.726(1982):Dry-type power transformers.Other publication quoted:ISO Standard 3746(1979):Acoustics-Determination of sound power levels of noise sources-Survey method.551IEC1987-7-DETERMINATION OF TRANSFORMERAND REACTOR SOUND LEVELS1.ScopeThis standard defines the methods by which the sound levels of transformers,reactors and theirassociated cooling equipment shall be determined so that compliance with any specification require-ments may be confirmed and the characteristics of the noise emitted in service determined.This standard is intended to apply to measurements made in the manufacturers works since con-ditions may be very different when measurements are made on site because of the proximity of otherobjects,background extraneous noises,etc.Nevertheless,the same general rules as are given hereinmay be followed when on-site measurements are made.In those cases where sufficient power is available in the factory to permit full energization of reac-tors,the methods to be followed are the same as for transformers.Such measurements shall be madeby agreement between the manufacturer and the purchaser.Alternatively,measurements may bemade on site where conditions are suitable.The methods are applicable to transformers and reactors covered by IEC Publications 76,726and 289,without further limitation as regards size or voltage and when fitted with their normalauxiliary equipment,inasmuch as it may influence the measurement result.Although the following text refers only to transformers,it is equally applicable to reactorsprovided that it is recognized that the current taken by a reactor is dependent on the voltage appliedand,consequently,that a reactor cannot be tested at no-load.This standard provides a basis for calculation of sound power levels.The methods of measurement and the environmental qualification procedure given in Appendix Aare in accordance with ISO Standard 3746.Measurements made in conformity with this IECstandard tend to result in standard deviations which are equal to or less than 3 dB.2.DefinitionsFor the purpose of this standard,the following definitions apply.2.1 Sound pressure level,LpThe value in decibels equal to twenty times the logarithm to the base of 10 of the ratio of thesound pressure to the reference sound pressure.Note.-For the purposes of this standard.A-weighted values of Le are used,i.e.LpA=A-weighted sound pressurelevel,and the reference sound pressure is 20 uPa.2.2 A-weighted surface sound pressure level,LThe A-weighted sound pressure level in decibels averaged over the measurement surface asrequired in Clause 6.5511EC198-9-2.3 Sound power level,LwThe value in decibels equal to ten times the logarithm to the base 10 of the ratio of a given soundpower to the reference sound powerNore.-For the purposes of this standard.A-weighted values of Lw are used,i.e.Lw=A-weighted sound power level.and the reference sound power is I pw(10-1:W).2.4 Principal radiating surfaceA hypothetical surface surrounding the transformer or cooling equipment which is assumed to bethe surface from which sound is radiated.Nore.-The method of determining the principal radiating surface for particular equipment is given in Sub-clause 5.2.2.5 Prescribed contourA horizontal line,spaced at a definite distaiice from the principal radiating surface,along whichthe measuring positions are located.Note.-The method for determining the prescribed contour for particular equipment is given in Sub-clause 5.2.2.6 Measurement surfaceA hypothetical surface of area S which envelops the source and on which the measuring positionsare located.Nore.-The methods for the determination of this area are given in Sub-clause 6.2.2.7 Measurement distanceThe distance between the principal radiating surface and the measurement surface.2.8 Background noiseThe A-weighted sound pressure level at each measuring position with conditions as given in Sub-clause 5.1,the test object being inoperative.3.InstrumentsMeasurements shall be made using a Type 1 sound level meter complying with IEC Publica-tion 651.An acoustic check of the measuring equipment using a calibrated noise source shall be madeimmediately before and after the measurement sequence.The instruments shall be calibrated in accordance with ISO Standard 3746.4.Conditions for measurement4.1 Criteria for adequacy of the test environmentIdeally,the test environment should be free from reflecting objects other than a reflecting floorso that the equipment under test radiates into a free field over a reflecting plane.Test environmentsthat are suitable for measurements according to this standard are those which meet the qualificationprocedures of Appendix A.