1、NORMEINTERNATIONALEINTERNATIONALSTAN DARDCEIIEC60268-11985AMENDEMENT 2AMENDMENT 21988-06Amendement 2Equipements pour systmes lectroacoustiquesPremire partie:GnralitsAmendment 2Sound system equipmentPart 1:General IEC 1988 Droits de reproduction rservs Copyright-all rights reservedInternational Elect
2、rotechnical Commission?3,rue de Varemb Geneva,SwitzerlandTelefax:+41 22 919 0300?e-mail:inmailiec.ch?IEC web site http:/www.iec.chIECCommission Electrotechnique InternationaleInternational Electrotechnical CommissionMerHAyr:apoaHas 3nenrporexHH4ecKan HOMHCCHACODE PRIX?nPRICE CODE?/Pour prix,voir cat
3、alogue en vigueurFor price,see current catalogueLICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.268-1 mod.2-2-Copyright CEIPREFACELa prsente modification a t tablie par le Comit dEtudes n 84 de laCEI:Equipements et systmes dans le doma
4、ine des techniques audio,vidoet audiovisuelles.Le texte de cette modification est issu des documents suivants:Procdure des Deux MoisRapport de vote84(BC)5284(BC)58Le rapport de vote indiqu dans le tableau ci-dessus donne toute infor-mation sur le vote ayant abouti lapprobation de cette modification.
5、Page 16Remplacer le paragraphe 12.1 par:12.1 Mthode de production dun champ magntique alternatif uniformeUne mthode commode et assez exacte pour produire un champmagntique alternatif uniforme fait appel trois bobines carresdisposes selon la figure 3,page 23,lespacement a entre bobinestant gal 0,375
6、fois la dimension b du ct de chaque carr.Lesbobines sont aliments avec un courant de frquence convenable.Les trois bobines ont respectivement des spires dans les rapports:nl=n2=n310036100Lorsque le mme courant I passe dans chaque bobine et dans lemme sens,il se produit un champ qui peut tre considr
7、commeuniforme dans les limites de 1-296 lintrieur dune zone sphrique dediamtre d=0,5 b dont le centre concide avec le centre de labobine 2.Le champ magntique rsultant H et linduction magntique B sontapproximativement:n 1n11 H=1,35 bA/mB=1,70 uTLintensit du champ magntique doit tre mesure avant que l
8、appa-reil mesurer ne soit plac dans le champ.Cela peut tre ralisavec une bobine exploratrice conforme celle qui est dcrite auparagraphe 12.2.LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.84(CO)5284(CO)58Two Months ProcedureReport on
9、Voting268-1 Amend.2-3-Copyright IECPREFACEThis amendment has been prepared by IEC Technical Committee No.84:Equipment and systems in the field of audio,video and audiovisualengineering.The text of this amendment is based upon the following documents:Full information on the voting for the approval of
10、 this amendment can befound in the Voting Report indicated in the above table.Page 17Replace Sub-clause 12.1 by:12.1 Method of producing a uniform alternating magnetic fieldA convenient and fairly accurate method of producing a uniformalternating magnetic field makes use of the arrangement of threes
11、quare coils according to Figure 3,page 23,in which a=0.375 b,where a is the distance between the coils and b the dimension of theside of each coil.The coils are supplied with a current at therequired frequency.The three coils 1,2 and 3 have turns in the ratios of:nl=n2=n310036100When the same curren
12、t I flows through each coil in the same direc-tion,a field is produced that may be considered to be uniform towithin 296,inside a spherical space having a diameter of d=0.5 b,the centre of which coincides with the geometrical centre of coil 2.The resulting magnetic field strength H and magnetic indu
13、ction Bare approximately:n11niH=1.35 bA/mB=1.70 b uTThe magnetic field strength shall be measured before the device isplaced into the field.This can be done with a search coil,in accor-dance with Sub-clause 12.2.LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.ICS 33.160.01Typeset and printed by the IEC Central OfficeGENEVA,SWITZERLANDLICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.