1、Amendment 2Environmental testing Part 2:Tests Tests A:ColdFor price,see current catalogue IEC 1994 Copyright-all rights reservedNo 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 wr
2、iting from the publisher.International Electrotechnical Commission,3,rue de Varemb,PO Box 131,CH-1211 Geneva 20,SwitzerlandTelephone:+41 22 919 02 11 Telefax:+41 22 919 03 00 E-mail:inmailiec.ch Web:www.iec.chINTERNATIONALSTANDARDIEC60068-2-11990AMENDMENT 21994-05DCommission Electrotechnique Interna
3、tionaleInternational Electrotechnical Commission PRICE CODEThis English-language version is derived from the originalbilingual publication by leaving out all French-languagepages.Missing page numbers correspond to the French-language pages.68-2-1 Amend.2 IEC:1994-3-FOREWORDThis amendment has been pr
4、epared by sub-committee 50B:Climatic tests,of IEC technical com-mittee 50:Environmental testing.The text of this amendment is based on the following documents:Full information on the voting for the approval of this amendment can be found in the report onvoting indicated in the above table.It also in
5、corporates the content of the Corrigendum,proposed in document 50B(Secretariat)349and some minor editorial changes._Page 35-Method AAdd:A flow diagrammatic representation of outline of method A is given in appendix D.Page 37-Method BAdd:A flow diagrammatic representation of outline of method B is gi
6、ven in appendix E.Following page 43Add the following new annexes D and E:DIS50B(CO)339Report on voting50B(CO)34368-2-1 Amend.2 IEC:1994-5-Annex DFlow diagrammatic representation of outlineof method A of test Ad(29.1.2)Stage 1The specimen is placed or assembled inside the test chamber.Both the chambe
7、r airflow and the cooling are switched off.Stage 2The specimen shall be subjected to the loading conditions specified for the lowtemperature test.Stage 3When temperature stability of the specimen has been reached,the temperature of anumber of representative points shall be measured and the temperatu
8、re rise whichoccurs at each point shall be noted.Stage 4The chamber air flow is switched on.When thetemperature stabilityhas been achieved,the temperatureof the representative points shall again bemeasured and compared with the temperatureof the same points measuredwithout air flow.Stage 6The veloci
9、ty of the air shall be reduced until the requirement of 3 K or any other tempe-rature difference specified by the relevant specification is met.Stage 5Is the requirementin stage 6 able to be metor not?Stage 8The chamber cooling is now switched on for the commencement of testing.Themeasuring of ambie
10、nt temperature shall be carried out in accordance with the definitionin 4.6.2 of IEC 68-1.Testing shall proceed in accordance with 29.1.1.Stage 9Stage 7ENDMethod B shallbe usedNoYesIf T is more than 3 K or any other temperature diffe-rence specified by the relevant specification.If T is less than3 K
11、 or any othertemperature differencespecified by the relevantspecification.68-2-1 Amend.2 IEC:1994-7-Annex EFlow diagrammatic representation of outlineof method B of test Ad(29.1.2)_Stage 1Stage 3The corrected temperature(Ts),based on the specified test temperature,shall bedetermined as described in
12、annex B.Stage 5The specimen shall be switched on or electrically loaded and the chamber shall becooled down.Testing shall proceed in accordance with 29.1.1.4 to 29.1.1.7ENDTesting shallproceed inaccordancewith 29.1.1.Stage 2The methodis notapplicableStage 4Stage 8if 25 K T1 80 KThe specimen shall be
13、 introduced into the chamber while both are at room temperature.Stage 6The temperature of the chamber shall be adjusted to and maintained at a value whichgives a temperature Ts at the surface of the specimen.Stage 7The specimen shall be subjected at the room ambient temperature(Ta)to the loadingcond
14、itions specified for the low temperature test.When the temperature stability of thespecimen has been reached,the temperature(Tsa)of the hottest point of the specimenshall be measured.The temperature T1 between the temperature of the hottest point(Tsa)on the specimen and the room ambienttemperature(Ta)shallbe measured.Tsa-Ta=T1if T1 80 K
