prEN IEC 60068-2-14:2022

Environmental testing - Part 2-14: Tests - Test N: Change of temperature

Umgebungseinflüsse - Teil 2-14: Prüfverfahren - Prüfung N: Temperaturwechsel

Essais d'environnement - Partie 2-14: Essais - Essai N: Variation de température

Okoljsko preskušanje - 2-14. del: Preskusi - Preskus N: Temperaturne spremembe

General Information

• Status: Not Published
• Publication Date: 14-Jan-2024
• ICS: 19.040 - Environmental testing
• Technical Committee: CLC/SR 104 - Environmental conditions, classification and methods of test
• Drafting Committee: IEC/TC 104 - IEC_TC_104
• Current Stage: 4060 - Enquiry results established and sent to TC, SR, BTTF - Enquiry
• Start Date: 16-Sep-2022
• Completion Date: 16-Sep-2022
• Ref Project: oSIST prEN IEC 60068-2-14:2022 - Environmental testing - Part 2-14: Tests - Test N: Change of temperature

Relations

• Revises: EN 60068-2-14:2009 - Environmental testing - Part 2-14: Tests - Test N: Change of temperature
• Effective Date: 26-Oct-2021

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN IEC 60068-2-14:2022
01-september-2022
Okoljsko preskušanje - 2-14. del: Preskusi - Preskus N: Temperaturne spremembe
Environmental testing - Part 2-14: Tests - Test N: Change of temperature
Umgebungseinflüsse - Teil 2-14: Prüfverfahren - Prüfung N: Temperaturwechsel
Essais d'environnement - Partie 2-14: Essais - Essai N: Variation de température
Ta slovenski standard je istoveten z: prEN IEC 60068-2-14:2022
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
oSIST prEN IEC 60068-2-14:2022 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60068-2-14:2022
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oSIST prEN IEC 60068-2-14:2022
104/933/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60068-2-14 ED7
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-06-24 2022-09-16
SUPERSEDES DOCUMENTS:
104/925/CD, 104/929A/CC
IEC TC 104 : ENVIRONMENTAL CONDITIONS, CLASSIFICATION AND METHODS OF TEST
SECRETARIAT: SECRETARY:
Sweden Mr Henrik Lagerström
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of

which they are aware and to provide supporting documentation.
TITLE:
Environmental testing - Part 2-14: Tests - Test N: Change of temperature
PROPOSED STABILITY DATE: 2027
NOTE FROM TC/SC OFFICERS:

Copyright © 2022 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to down-

load this electronic file, to make a copy and to print out the content for the sole purpose of preparing National

Committee positions. You may not copy or "mirror" the file or printed version of the document, or any part of it,

for any other purpose without permission in writing from IEC.
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1 CONTENTS

2 FOREWORD......................................................................................................................... 4

3 INTRODUCTION ................................................................................................................... 6

4 1 Scope ............................................................................................................................ 7

5 2 Normative references ..................................................................................................... 7

6 3 Terms and definitions ..................................................................................................... 7

7 4 List of symbols ............................................................................................................... 8

8 5 General .......................................................................................................................... 8

9 5.1 Field conditions of changing temperature ............................................................... 8

10 5.2 Design of tests with temperature change ................................................................ 9

11 5.3 Test parameters .................................................................................................... 9

12 5.4 Purpose and choice of the tests ............................................................................. 9

13 5.5 Choice of the exposure time to each conditioning temperature .............................. 10

14 5.6 Choice of the duration of the transfer time t2 ........................................................ 10

15 5.7 Applicability limits of change of temperature tests ................................................ 11

16 6 Guidance for the selection of the kind of test ................................................................. 11

17 7 Initial and final measurements ...................................................................................... 12

18 7.1 Initial measurements ............................................................................................ 12

19 7.2 Final measurements ............................................................................................ 12

20 8 Test Na: Rapid change of temperature .......................................................................... 12

21 8.1 General description of the test ............................................................................. 12

22 8.2 Testing procedure ................................................................................................ 12

23 8.2.1 Testing chamber ...................................................................................... 12

24 8.2.2 Mounting or supporting of the test specimen ............................................. 14

25 8.2.3 Severities ................................................................................................ 14

26 8.2.4 Preconditioning ........................................................................................ 16

27 8.2.5 Test cycle ................................................................................................ 16

28 8.3 Recovery ............................................................................................................. 18

29 9 Test Nb: Change of temperature with specified rate of change ....................................... 18

30 9.1 General description of the test ............................................................................. 18

31 9.2 Testing procedure ................................................................................................ 19

32 9.2.1 Testing chamber ...................................................................................... 19

33 9.2.2 Mounting or supporting structure of the test specimen............................... 19

34 9.2.3 Severities ................................................................................................ 19

35 9.2.4 Tolerance ................................................................................................ 19

36 9.2.5 Preconditioning ........................................................................................ 21

37 9.3 Test cycle ............................................................................................................ 21

38 9.4 Recovery ............................................................................................................. 23

39 10 Test Nc: Rapid change of temperature, two-fluid-bath method ....................................... 23

40 10.1 General description of the test ............................................................................. 23

41 10.2 Testing procedure ................................................................................................ 23

42 10.2.1 Testing equipment ................................................................................... 23

43 10.2.2 Severities ................................................................................................ 23

44 10.2.3 Conditioning ............................................................................................ 24

45 10.3 Test cycle ............................................................................................................ 24

46 10.4 Recovery ............................................................................................................. 24

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47 11 Information to be given in the test report ....................................................................... 25

48 Annex A Potential consequences of improper severities ...................................................... 26

49 Annex B Thermal responsiveness of different materials and geometries .............................. 27

50 Annex C Auxiliary table with exemplary temperature tolerances ±σT for pre-ferred

51 combinations of high and low conditioning temperatures and rates of temperature

52 change (Test Nb) ................................................................................................................ 28

55 Figure 1 – Determination of the exposure time of the specimen to each conditioning

56 temperature (t1) .................................................................................................................. 10

57 Figure 2 – Schematic representation of examples of thermal test cabinets and test

58 procedure with two separate test chambers ......................................................................... 13

59 Figure 3 – Schematic representation of examples of thermal test cabinets with one test

60 chamber ............................................................................................................................. 13

61 Figure 4 – Possibility of condensation during rapid temperature change ............................... 14

62 Figure 5 – Possibility of condensation during transfer of the specimen ................................. 14

63 Figure 6 – Increased severity of test Na .............................................................................. 15

64 Figure 7 – Na test cycle, one-chamber method .................................................................... 16

65 Figure 8 – Na test cycle, two-chamber method .................................................................... 18

66 Figure 9 – Tolerance for fluctuation of test temperatures ..................................................... 21

67 Figure 10 – Nb test cycle .................................................................................................... 22

68 Figure 11 – Test times for intermediate operation of specimens ........................................... 22

69 Figure 12 – Nc test cycle .................................................................................................... 24

70 Figure A.1 – Delayed temperature change of the specimen .................................................. 26

71 Figure B.1 – Rate of temperature change of specimen with differing thermal

72 responsiveness ................................................................................................................... 27

73 Figure C.1 –Tolerance for fluctuation of test temperatures for exemplary test

74 parameters ......................................................................................................................... 29

76 Table C.1 – Applicable temperature tolerances ±σ in [K] for preferred combinations of

77 high and low conditioning temperatures and rates of temperature change dT ...................... 28

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80 INTERNATIONAL ELECTROTECHNICAL COMMISSION
81 ____________
83 ENVIRONMENTAL TESTING –
85 Part 2-14: Tests – Test N: Change of temperature
88 FOREWORD

89 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

90 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

91 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

92 in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

93 Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publicati on(s)”). Their prepa-

94 ration is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may

95 participate in this preparatory work. International, governmental and non-governmental organizations liaising with

96 the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Stand-

97 ardization (ISO) in accordance with conditions determined by agreement between the two organizations.

98 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

99 consensus of opinion on the relevant subjects since each technical committee has representation from all inter-

100 ested IEC National Committees.

101 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

102 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

103 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinter-

104 pretation by any end user.

105 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications trans-

106 parently to the maximum extent possible in their national and regional publications. Any divergence between any

107 IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

108 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment

109 declared to be in conformity with an IEC Publication.

110 6) All users should ensure that they have the latest edition of this publication.

111 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

112 members of its technical committees and IEC National Committees for any personal injury, property damage or

113 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and ex-

114 penses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.

115 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

116 indispensable for the correct application of this publication.

117 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

118 rights. IEC shall not be held responsible for identifying any or all such patent rights.

119 International Standard IEC 60068-2-14 has been prepared by IEC technical committee 104:

120 Environmental conditions, classification and methods of test.

121 This seventh edition cancels and replaces the sixth edition, published in 2009 and constitutes

122 a technical revision.
123 The major changes with regard to the previous edition concern:

124 • updating of the figures, changes to some of the wording and editorial corrections made for

125 clarification.

126 • Updating specimen temperature(s) and severities as well as tolerances for change of tem-

127 perature tests.
128 • Standardized requirements for test reports for tests Na, Nb and Nc
129
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130 The text of this standard is based on the following documents:
FDIS Report on voting
XXX/XXX/FDIS XXX/XXX/RVD
131

132 Full information on the voting for the approval of this standard can be found in the report on

133 voting indicated in the above table.

134 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

135 A list of all the parts in the IEC 60068 series, under the general title Environmental testing, can

136 be found on the IEC website.

137 The committee has decided that the contents of this publication will remain unchanged until the

138 maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data

139 related to the specific publication. At this date, the publication will be
140 • reconfirmed,
141 • withdrawn,
142 • replaced by a revised edition, or
143 • amended.
144
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145 INTRODUCTION

146 A change of temperature test is intended to determine the effect on the specimen of a change

147 of temperature or a succession of changes of temperature.

148 It is not intended to show effects that are caused by low or high temperature exposure. For

149 these effects, the cold test or the dry heat test, as specified in IEC 60068-2-1 and IEC 60068-

150 2-2, should be used.
151 The effect of change of temperature tests is determined by

152 – values of high and low conditioning temperature between which the change is to be affected,

153 – the conditioning times for which the test specimen is kept at these temperatures,

154 – the rate of change between these temperatures,
155 – the number of cycles of conditioning,
156 – the amount of heat transfer into or from the specimen,
157 – the thermal conductivity and the materials of the specimen,

158 – the rate of change of the specimen’s temperature on its surface (respectively in relevant

159 positions) or in its core.

160 Guidance on the choice of suitable test parameters for inclusion in the detail specification is

161 given throughout this standard.
162
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163 ENVIRONMENTAL TESTING –
164
165 Part 2-14: Tests – Test N: Change of temperature
166
167
168
169 1 Scope

170 This part of IEC 60068 provides tests with specified ambient temperature changes to analyse

171 their impacts on specimen.
172 2 Normative references

173 The following documents are referred to in the text in such a way that some or all of their content

174 constitutes requirements of this document. For dated references, only the edition cited applies.

175 For undated references, the latest edition of the referenced document (including any amend-

176 ments) applies.
177 IEC 60068 (all parts), Environmental testing
178 IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
179 IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat

180 IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)

181 IEC 60068-2-17, Environmental testing – Part 2-17: Tests – Test Q: Sealing

182 IEC 60068-2-67, Environmental testing – Part 2-67: Tests – Test Cy: Damp heat, steady state,

183 accelerated test primarily intended for components
184 3 Terms and definitions

185 For the purposes of this document, the terms and definitions given in IEC 60068-2-1 and IEC

186 60068-2-2 apply.
187 No terms and definitions are listed in this document.

188 ISO and IEC maintain terminological databases for use un standardization at the following ad-

189 dresses:
190 • IEC Electropedia: available at http://www.electropedia.org/
191 • ISO online browsing platform: available at http://www.iso.org/obp
192
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193 4 List of symbols
temperature difference between high conditioning temperature 𝑇 and low con-
ditioning temperature 𝑇
𝑇 low conditioning temperature
𝑇 decreased low conditioning temperature
𝐴𝑑
𝑇 high conditioning temperature
𝑇 increased high conditioning temperature
𝐵𝑖
𝑇 standard atmospheric conditions (15 °C to 35 °C)
𝑆𝑇𝐷
𝛥𝑇 temperature difference between the specimen and the test medium (e.g. air)
𝑑𝑇 temperature change rate (Test Nb)
𝑡 stabilization time of specimen temperature
stabilization time of specimen temperature during the first cycle, starting from
laboratory air temperature
𝑡 exposure time of the specimen to each conditioning temperature
transfer time of the specimen from one test chamber to another (two-chamber
test method)
applicable temperature tolerance of the medium temperature during tempera-
±𝜎
ture transition (Test Nb)
applicable temperature tolerance of the medium temperature during the con-
±𝜎
𝑇𝑐𝑜𝑛𝑠𝑡
stant conditioning
194 5 General
195 5.1 Field conditions of changing temperature

196 It is common in electronic equipment and components that changes of temperature occur. Parts

197 inside equipment undergo slower changes of temperature than those on an external surface

198 when the equipment is not switched on.
199 Rapid changes of temperature may be expected

200 – when equipment is transported from warm indoor into cold outdoor environments or vice

201 versa,
202 – when equipment is suddenly cooled by rainfall or immersion in cold water,

203 – when equipment is attached or in close proximity to components leading to high thermal

204 stress (e.g. combustion engines, central processing units),
205 – when equipment is artificially cooled or heated,
206 – in externally mounted airborne equipment,
207 – under certain conditions of transportation and storage.

208 Components will undergo stresses due to changing temperature when high temperature gradi-

209 ents build up in an equipment after being switched on, e.g. in the proximity of high power resis-

210 tors, radiation can cause rise of the surface temperature on close components while other por-

211 tions remain cold.

212 Artificially cooled components may be subjected to rapid temperature changes when the cooling

213 system is switched on. Rapid changes of temperature in components may also be induced

214 during manufacturing processes or the transportation of equipment. Both the number and

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215 amplitude of temperature changes, the time interval between them and the thermal responsive-

216 ness of the equipment (or specimen) are important.
217 5.2 Design of tests with temperature change

218 Change of temperature Tests Na, Nb and Nc comprise alternate periods at a high and a low

219 temperature with well-defined transfers from one temperature to the other. The conditioning run

220 from laboratory ambient to the first conditioning temperature, then to the second conditioning

221 temperature, then back to laboratory ambient is considered one test cycle.
222 5.3 Test parameters
223 Test parameters comprise the following:
224 – laboratory ambient conditions (mainly temperature and humidity);
225 – high conditioning temperature 𝑇 ;
226 – increased high conditioning temperature 𝑇 , if applicable;
𝐵𝑖
227 – low conditioning temperature 𝑇 ;
228 – decreased low conditioning temperature 𝑇 , if applicable;
𝐴𝑑
229 – exposure time of the specimen to each conditioning temperature 𝑡 ;
230 – transfer time 𝑡 or temperature change rate 𝑑𝑇 ;
2 R
231 – number of test cycles.

232 NOTE The high and low conditioning temperatures are understood to be ambient temperatures which will be

233 reached by most specimens with a certain time-lag.

234 As these tests are intended to validate the effects of temperature changes on the specimen,

235 the specimen’s characteristics should always be taken into consideration (if not specified oth-

236 erwise):
237 − thermal responsiveness of the specimen in affected areas or the core;
238 o thermal conductivity;
239 o specific heat capacity;
240 − density;
241 − geometry;
242 − mass.

243 The experimental determination of these characteristics is recommended, if unknown and not

244 specified otherwise.

245 The test is accelerated because the number of severe changes of temperature in a given period

246 is greater than that which will occur under field conditions.

247 The high and low temperatures are understood to be ambient temperatures which will be

248 reached by most specimens with a certain time-lag.

249 Only in exceptional cases may these temperatures be specified outside the normal storage or

250 operating temperature range of the object under test.

251 NOTE If the specimen’s characteristics (mass, density, geometry) prevent the specified rate of change, the tem-

252 peratures may be specified outside the normal storage or operating temperatures in order to increase the severity of

253 the intended test, if not specified otherwise.
254 5.4 Purpose and choice of the tests
255 Change of temperature testing is recommended in the following cases:
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256 – evaluation of electrical performance after a specified number of rapid changes of tempera-

257 ture, Test Na or Test Nc;

258 – evaluation of the suitability of mechanical components, and of materials and combinations

259 of materials to withstand rapid changes of temperature, Test Na or Test Nc;

260 – evaluation of the suitability of construction of components to withstand artificial stressing,

261 Test Na or Test Nc;

262 – evaluation of electrical performance during a change of temperature, Test Nb;

263 – evaluation of mechanical performance during a change of temperature, Test Nb.

264 The change of temperature tests specified in the IEC 60068 series is not intended to evaluate

265 the difference in material constants or electrical performance when operating under the condi-

266 tioning temperatures 𝑇 and 𝑇 .
𝐴 𝐵
267 5.5 Choice of the exposure time to each conditioning temperature

268 The duration of the exposure should be based on the requirements stated in 8.2.3, 9.2.3 or

269 10.2.2, or as stated in the relevant specification, keeping in mind the following points:

270 a) The exposure begins as soon as the specimen is in the new environment.

271 b) Stabilization occurs when the temperature difference between the specimen and the

272 test medium (𝛥𝑇 ) is within 3 K to 5 K, or as stated in the test specification. The

273 stabilization time of specimen temperature 𝑡 is from the start of exposure until the

274 moment when the temperature is within the specified difference. A representative point

275 (or points) on the specimen may be used for this measurement.

276 c) The exposure time of the specimen to each conditioning temperature 𝑡 shall be longer

277 than the stabilization time of the specimen temperature 𝑡 . Figure 1 provides a graphical

278 representation of the process. This may not be appropriate for heat generating

279 specimens.
Temperature of
the specimen
T
Time
280

281 Figure 1 – Determination of the exposure time of the specimen to each conditioning

282 temperature (𝒕 )
283 5.6 Choice of the duration of the transfer time 𝒕

284 If, e.g. due to the large size of the specimens, the transfer time 𝑡 cannot be kept within in 3

285 min, the transfer time may be increased with a negligible influence on the test results as follows:

Temperature
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286 𝑡  0,05 𝑡
2 S
287 where
288 𝑡 is the duration of the transfer time;
289 𝑡 is stabilization time of specimen temperature.

290 This applies for the two-chamber test (see 8.2.1) method only. When using the one-chamber

291 test method, period 𝑡 is not applicable.
292 5.7 Applicability limits of change of temperature tests

293 Inside a specimen, the temperature change rate depends on the heat conduction of its materials,

294 the spatial distribution of its heat capacity as well as on its dimensions and surface. A

295 representative point (or points) on (or inside) the specimen may be used for the measurement

296 of the temperature change rates.

297 NOTE 1 The rate of temperature change of specimens made of the same material and mass can vary if their sur-

298 faces differ from each other.

299 The change of temperature at one point on the surface of a specimen follows approximately an

300 exponential law. Inside large specimens, such alternate exponential rises and decreases may

301 lead to periodic and approximately sinusoidal changes of temperature with much lower ampli-

302 tudes than the applied temperature swing.

303 The mechanism of heat transfer between the test specimen and the conditioning medium in the

304 chamber or bath should be taken into account. Liquid in motion leads to very high rates of

305 change of temperature on the surface of the specimens and still air to very low rates.

306 NOTE 2 If more than one specimen is tested in the same test chamber, a uniform incoming airflow could be dis-

307 turbed. For further information on the relation of airflow and specimen temperature, IEC 60068-3-1 may be helpful.

308 The two-bath method with water as a conditioning medium (Test Nc) should be restricted to

309 specimens which are either sealed or are by their nature insensitive to water, since their per-

310 formance and properties may deteriorate by immersion.

311 In particular cases, such as with specimens sensitive to water, a test with liquid other than water

312 should be specified. When designing such a test, the characteristics of heat transfer of the

313 liquid, whic
...