International Electrotechnical Vocabulary - Part 101: Mathematics

It has the status of a horizontal standard in accordance with IEC Guide 108.

Vocabulaire Electrotechnique International - Partie 101: Mathématiques

Elle a le statut d'une norme horizontale conformément au Guide 108 de la CEI.

[Not translated]

General Information

Status
Not Published
Technical Committee
Current Stage
6100 - Translation of adopted SIST standards (Adopted Project)
Start Date
19-Nov-2014
Due Date
18-Nov-2015

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IEC 60068-3-5
®

Edition 2.0 2018-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Environmental testing –
Part 3-5: Supporting documentation and guidance – Confirmation of the
performance of temperature chambers

Essais d’environnement –
Partie 3-5: Documentation d’accompagnement et guide – Confirmation des
performances des chambres d’essai en température

IEC 60068-3-5:2018-01(en-fr)

---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60068-3-5

®


Edition 2.0 2018-01




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Environmental testing –

Part 3-5: Supporting documentation and guidance – Confirmation of the

performance of temperature chambers




Essais d’environnement –

Partie 3-5: Documentation d’accompagnement et guide – Confirmation des


performances des chambres d’essai en température













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 19.040 ISBN 978-2-8322-6968-8




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – IEC 60068-3-5:2018 © IEC 2018
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Measuring chamber performances . 8
4.1 Test area environment . 8
4.2 Temperature measurement system . 8
4.3 Temperature chamber test specimens . 8
4.4 Specified location of temperature sensors in working space . 9
4.5 Measurement method . 10
4.5.1 General . 10
4.5.2 Achieved temperature . 10
4.5.3 Temperature stabilization . 10
4.5.4 Temperature fluctuation . 11
4.5.5 Temperature gradient . 12
4.5.6 Temperature variation in space . 12
4.5.7 Temperature rate of change . 13
4.6 Standard temperature sequence . 14
5 Information to be given in the performance test report . 14
Bibliography . 16

Figure 1 – Working space . 7
Figure 2 – Example of temperature differences . 8
Figure 3 – Location sensors for temperature chambers up to 2 000 l . 9
Figure 4 – Location of minimal additional sensors for temperature chambers
over 2 000 l . 9
Figure 5 – Example of achieved temperature . 10
Figure 6 – Example of temperature stabilization for chambers up to 2 000 l . 11
Figure 7 – Example of temperature fluctuation . 11
Figure 8 – Example of temperature gradient for chambers up to 2 000 l . 12
Figure 9 – Example of temperature gradient for chambers <2 000 L . 13
Figure 10 – Example of temperature rate of change . 14

Table 1 – Practical dimensions . 7

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IEC 60068-3-5:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ENVIRONMENTAL TESTING –

Part 3-5: Supporting documentation and guidance –
Confirmation of the performance of temperature chambers

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60068-3-5 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
This bilingual version (2019-05) corresponds to the monolingual English version, published in
2018-01.
This second edition cancels and replaces the first edition published in 2001. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Confirmation procedures are clarified.

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– 4 – IEC 60068-3-5:2018 © IEC 2018
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/759/FDIS 104/778/RVD

Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60068 series, published under the general title Environmental
testing, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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IEC 60068-3-5:2018 © IEC 2018 – 5 –
INTRODUCTION
IEC 60068 (all parts) contains fundamental information on environmental testing procedures
and severities.
The expression "environmental conditioning" or "environmental testing" covers the natural and
artificial environments to which components or equipment may be exposed so that an
assessment can be made of their performance under conditions of use, transport and storage
to which they may be exposed in practice.
Temperature chambers used for "environmental conditioning" or "environmental testing" are
not described in any publication, although the method of maintaining and measuring
temperature and/or humidity has a great influence on test results. The physical characteristics
of temperature chambers can also influence test results.

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– 6 – IEC 60068-3-5:2018 © IEC 2018
ENVIRONMENTAL TESTING –

Part 3-5: Supporting documentation and guidance –
Confirmation of the performance of temperature chambers



1 Scope
This part of IEC 60068 provides a uniform and reproducible method of confirming that
temperature test chambers, without specimens, conform to the requirements specified in
climatic test procedures of IEC 60068-2 (all parts) and other standards. This document is
intended for users when conducting regular chamber performance monitoring.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60068-2 (all parts), Environmental testing – Part 2: Tests
IEC 60068-3-7, Environmental testing – Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for tests A and B (with load)
IEC 60068-3-11, Environmental testing – Part 3-11: Supporting documentation and guidance
– Calculation of uncertainty of conditions in climatic test chambers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
temperature test chamber
enclosure or space in some parts of which the temperature conditions, specified in
IEC 60068-2 (all parts), can be achieved
3.2
temperature setpoint
desired temperature as set by the chamber controls
3.3
achieved temperature
stabilized temperature which desired temperature at the centre of the working space achieves
within specified tolerance

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IEC 60068-3-5:2018 © IEC 2018 – 7 –
3.4
temperature stabilization
state of maintaining temperature within specified tolerance during specified time at specified
points in the working space
3.5
temperature fluctuation
difference, after stabilization, between the maximum and minimum temperatures at specified
point in the working space during a specified interval of time
Note 1 to entry: For calibration, the centre point of working space may be used.
3.6
working space
part of the chamber in which the specified conditions can be maintained within the specified
tolerances
Note 1 to entry: See Figure 1 and Table 1.
X
3
L
3
X
3
X
X
2
1
X X
1 2
L L
1 2
IEC

Figure 1 – Working space
Table 1 – Practical dimensions
Size Volume Distance X X (min.)
l
mm mm
Small Up to 1 000 L/10 50
Medium 1 000 to 2 000 L/10 100
Large More than 2 000 L/10 150
NOTE Not all chambers are cubic in construction.

3.7
temperature gradient
maximum difference in mean value, after stabilization, at any moment in time between two
separate points in the working space
3.8
temperature variation in space
difference in mean value, after stabilization, at any moment in time between the temperature
at the centre of the working space and at any other point in the working space

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– 8 – IEC 60068-3-5:2018 © IEC 2018
3.9
temperature rate of change
rate, in kelvin per minute, for the transition between two specified temperatures measured at
the centre of the working space
Note 1 to entry: See Figure 2.
Temperature fluctuation
outside the centre of
working space (see 3.5)
Temperature fluctuation
in the centre of
working space (see 3.6)
Temperature fluctuation
outside the centre of
working space (see 3.5)
Time
IEC

Figure 2 – Example of temperature differences
4 Measuring chamber performances
4.1 Test area environment
The environment around a temperature test chamber may influence the conditions inside the
test chamber.
The confirmation of performance of temperature chambers should be carried out under
standard atmospheric conditions specified in IEC 60068-1.
4.2 Temperature measurement system
The uncertainty of measurement of the output of the measurement system should be
determined by calibration of the system, traceable to international standards (see ISO 10012).
The temperature sensors may be either calibrated platinum resistors or a thermocouple. The
thermal response time of the sensors shall be within a minimum of 10 s and a maximum of
40 s for 50 % of response. It is preferred that the thermal response time of the entire
measurement system to be less than 40 s. The use of sensors that are compliant to
IEC 60584-1 tolerance class 1 (for thermocouples) or IEC 60751 tolerance class A (for
resistors) is recommended.
4.3 Temperature chamber test specimens
All measurements described in 4.5 are performed with an empty working space. For
measuring with test specimens (with or without heat dissipation), see IEC 60068-3-7.

Temperature
Variation
(see 3.8)
Gradient
(see 3.7)

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IEC 60068-3-5:2018 © IEC 2018 – 9 –
4.4 Specified location of temperature sensors in working space
Temperature measuring sensors are located in each corner and in the centre of the working
space (see Figure 3, minimum 9 sensors). For temperature chambers over 2 000 l, additional
sensors should be located in front of the centre of each wall (see Figure 4, minimum
15 sensors). The measuring system is to be arranged in such a way that the temperature
distribution of the empty test chamber will not be affected. For a large capacity chamber,
there may be a significant difference between the temperature control sensor(s) and the
temperature at the centre of the working space. It may be necessary to adjust the temperature
setting to achieve the necessary tolerance.
N
2
N
3
L
3 N
1
10 N
4
Centre
N
5
L
3
N
7
N
8
N
6
L
2
N
9
10
L
3
10
L
L
2
2
10
L
1
L
10
1
10
L
1
IEC

Figure 3 – Location of sensors for
temperature chambers up to 2 000 l
X
2
X
1
IEC

Figure 4 – Location of minimal additional sensors for
temperature chambers over 2 000 l

X
3

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– 10 – IEC 60068-3-5:2018 © IEC 2018
For confirmation monitoring, data should be recorded at least once a minute. The device used
for recording data from the chamber monitoring sensors should be independent of the
chamber control system.
4.5 Measurement method
4.5.1 General
The temperature output of the temperature measuring system (see Figure 3 or Figure 4)
determines, after chamber stabilization, the achieved temperature, temperature fluctuation
and temperature gradient of the working space. For tolerance, the specification of the
temperature/humidity chamber or, as necessary, tolerance specified in IEC 60068-2 (all parts),
is required to maintain at the centre of the working space. Location of sensor is minimum 9
points or 15 points. This depends on the test chamber size. The measurement method is
explained based on 9 points.
Uncertainty of measurement of the temperature measuring system shall be according to
IEC 60068-3-11.
4.5.2 Achieved temperature
Temperature is achieved when the centre of the working space maintains the tolerance as
required by IEC 60068-2 (all parts). An example is shown in Figure 5.
T
1
N
Tolerance 5
Temperature
setting
IEC

For tolerance, check the specification of the temperature chamber, or, as necessary, use tolerance specified in
IEC 60068-2 which is required to maintain at the centre of the working space.
T must be minimum 30 min. N is the temperature at the centre of the working space.
1
5
Figure 5 – Example of achieved temperature
4.5.3 Temperature stabilization
Temperature reached and maintained within the allowable range in the working space is
shown in Figure 6. Allowable range is based on the temperature fluctuation, temperature
variation in space, and temperature gradient as the temperature chamber specification.
Specified time T is minimum 30 min after the measurement points (e.g. N to N ) are within
2 1 9
the allowable range.

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IEC 60068-3-5:2018 © IEC 2018 – 11 –
T
2
N
1
Allowable
range

N
9
IEC

Figure 6 – Example of temperature stabilization for chambers up to 2 000 l
4.5.4 Temperature fluctuation
The fluctuation during a specified interval of time at specified temperature points in the
working space, after temperature stabilization, is shown in Figure 7.
N
Max
+2σ
n–1
+1σ
n–1
–1σ
n–1
Average
temperature N
Ave
σ
n–1
Specimen standard

deviation
–2σ
n–1
N
Min
0 5 10 15 20 25 30
Time (min)
IEC

Figure 7 – Example of temperature fluctuation
Measurements are actually made at a certain sampling interval. It is not guaranteed that data
captures the fluctuation peak. For that reason, the sample standard deviation, 𝜎𝜎 shall be
𝑛𝑛−1
obtained from the data measured in each measurement point after temperature has stabilized,
and the temperature fluctuation shall be within ±2𝜎𝜎 .
𝑛𝑛−1

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– 12 – IEC 60068-3-5:2018 © IEC 2018
The temperatures measured in a certain measurement point, after stabilization, over a
30-minute period 10 or more times at even intervals shall be as follows.
N , N , … , N , …  N (n≧10)
1 2 i n
The mean of N shall be N .
Ave
The specimen standard deviation, 𝜎𝜎 shall be defined as follows.
𝑛𝑛−1

2

(𝑋𝑋−𝑁𝑁 )
𝑖𝑖 𝐴𝐴𝐴𝐴𝐴𝐴

𝜎𝜎 =
𝑛𝑛−1
𝑛𝑛−1
Temperature fluctuation ±2𝜎𝜎 shall be obtained in all 9 measurement points, and the highest
𝑛𝑛−1
value within that shall be annotated as the temperature fluctuation.
4.5.5 Temperature gradient
As shown in Figure 8, the maximum difference in mean temperature in all measurement points
of the effective space shall be the temperature gradient.
N
AveMax
N
AveMin
0 5 10 15 20 25 30
Time (min)
IEC

N : Mean highest temperature in each of 9 measurement points
AveMax
N : Mean lowest temperature in each of 9 measurement points
AveMin
Temperature gradient = N – N

AveMax AveMin
Figure 8 – Example of temperature gradient for chambers up to 2 000 l
4.5.6 Temperature variation in space
As shown in Figure 9, temperature variation in space is the difference of the mean
temperature at the centre of the working space and the mean temperature of another

Temperature gardient

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IEC 60068-3-5:2018 © IEC 2018 – 13 –
measurement point. The maximum difference between the centre of the working space and
each measuring point shall be stated.

N
CornerAve
N
CenterAve
N
CornerAve
0 5 15 20 25 30
Time (min)
IEC


N : Mean temperature at chamber center
CenterAve
N j=1 to 8: Mean temperature at corner of working space
CornerAve(j)
Temperature variation in space =|Max(N – N )|
CornerAve[j] CenterAve
The value obtained as the temperature variation in space shall be (N – N ), and the absolute value
CornerAve(j) CenterAve
of the highest difference obtained for the 8 corners shall be annotated as the temperature variation in space
Figure 9 – Example of temperature gradient for chambers <2 000 L
4.5.7 Temperature rate of change
As shown in Figure 10, temperature rate of change between specified temperatures shall be
calculated with the following method, and indicated in K/min.
Temperature heat-up rate = Δt/T

Temperature cool-down rate = Δt/T
2

Temperature variation in space

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– 14 – IEC 60068-3-5:2018 © IEC 2018
Heat-up Cool-down
Time T Time T
1 2
Highest
100 %
temperature
90 %
10 %
Lowest
0 %
temperature

IEC
Figure 10 – Example of temperature rate of change
To measure temperature rate of change:
• adjust chamber to lowest specified temperature and allow to stabilize;
• adjust chamber to highest specified temperature, monitoring the time between the 10 %
and the 90 % points of the temperature range;
• allow chamber to stabilize at the highest specified temperature;
• adjust chamber to lowest specified temperature, monitoring the time between the 90 %
and 10 % points of temperature range.
4.6 Standard temperature sequence
The following test sequence is considered to be the minimum recommended to obtain the
necessary data for confirmation of the performance of a temperature chamber.
The test sequence is as follows:
• start at ambient conditions;
• adjust chamber to highest specified temperature and allow chamber to stabilize;
• measure performance at highest temperature;
• adjust chamber to lowest specified temperature, monitoring rate of change and allow
chamber to stabilize;
• measure performance at lowest temperature;
• adjust chamber to highest specified temperature, monitoring rate of change;
• adjust chamber to atmospheric conditions and allow chamber to stabilize;
• measure performance at atmospheric conditions.
5 Information to be given in the performance test report
As a minimum, the following information shall be contained in the test report.

∆t

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IEC 60068-3-5:2018 © IEC 2018 – 15 –
a) Atmospheric conditions in the test area for measurement.
b) Size and volume of chamber enclosure and working space.
c) Temperature fluctuation, temperature variation in space and temperature gradient.
d) Temperature rate of change.
e) Highest/Lowest temperature.
f) Measurement results from each measurement position.
g) Details of data acquisition systems.
h)
...

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