IEC 60068-3-7:2020
(Main)Environmental testing - Part 3-7: Supporting documentation and guidance - Measurements in temperature chambers for tests A (Cold) and B (Dry heat) (with load)
Environmental testing - Part 3-7: Supporting documentation and guidance - Measurements in temperature chambers for tests A (Cold) and B (Dry heat) (with load)
IEC 60068-3-7:2020 specifies a uniform and reproducible method of confirming that temperature test chambers conform to the requirements specified in the climatic test procedures of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-dissipating specimens under conditions which take into account air circulation inside the working space of the chamber. This document is intended primarily for users when conducting regular chamber performance monitoring. 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:
- verbal forms have, in many parts, been changed to express requirements instead of recommendations ('shall' instead of 'should');
- Table 1 has been updated.
Essais d'environnement - Partie 3-7: Partie 3-7: Documentation d'accompagnement et recommandations - Mesurages dans les chambres d'essai en température pour les essais A (froid) et B (chaleur sèche) (avec charge)
L'IEC 60068-3-7:2020 spécifie une méthode uniforme et reproductible pour confirmer que les chambres d'essai en température respectent les exigences spécifiées dans les procédures d'essai climatique de l'IEC 60068-2-1 et de l'IEC 60068-2-2 lorsqu'elles sont chargées de spécimens dissipateurs d'énergie ou non, dans des conditions qui tiennent compte d'une circulation d'air à l'intérieur de l'espace de travail de la chambre. Le présent document s'adresse en premier lieu aux utilisateurs qui effectuent une surveillance régulière des performances des chambres. Cette deuxième édition annule et remplace la première édition parue en 2001. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- dans plusieurs parties, les formes verbales ont été remplacées par des exigences explicites en lieu et place des recommandations ("devoir" au lieu de "il convient");
- le Tableau 1 a été mis à jour.
General Information
Relations
Overview
IEC 60068-3-7:2020 is an IEC supporting guidance standard for environmental testing that specifies a uniform, reproducible method to confirm the performance of temperature chambers used for Test A (Cold) and Test B (Dry heat) when operated with load. This edition (2.0, 2020) replaces the 2001 edition and tightens requirements (many recommendations changed to shall). It is intended primarily for users conducting regular chamber performance monitoring, acceptance checks and routine validation of chamber conformity to IEC 60068-2-1 and IEC 60068-2-2 procedures.
Key Topics and Requirements
- Scope and purpose
- Confirms chamber performance under realistic loaded conditions (heat-dissipating and non-heat-dissipating specimens) and accounts for internal air circulation.
- Measuring system
- Requirements for measurement hardware and recording devices used during confirmation and monitoring.
- Sensors
- Temperature sensors (placement, types and response), humidity sensors where applicable, and air velocity sensors (including response time).
- Wall properties and emissivity
- Guidance on wall emissivity and its effect on radiative heat transfer inside the working space.
- Test area and chamber loading
- Defines test area environment, location and installation of test loads, and artificial load design.
- Artificial load specification
- Recommended artificial load: volume ≈ 20% of working space, emissivity > 0.7, heat transmission ≈ 10 kJ/m²K; suggested sheet thickness examples (s = 3 mm stainless steel or 4 mm aluminium).
- Procedures
- Two principal procedures: confirmation method (continuous measurements to establish conformity) and routine monitoring (continuous or periodic checks).
- Evaluation and reporting
- Clear evaluation criteria and required information to be included in a chamber performance report.
Applications and Who Uses It
- Acceptance and commissioning of temperature chambers for environmental labs.
- Routine performance monitoring and calibration verification for test houses.
- Manufacturers and quality engineers validating chamber suitability for Test A (Cold) and Test B (Dry heat) programs.
- Test laboratory managers, calibration technicians, and compliance engineers responsible for repeatable, reproducible environmental testing.
Practical Value
- Ensures test chambers produce reliable, repeatable temperature environments under load, reducing false pass/fail results.
- Helps define sensor placement, artificial load construction and test procedures to mimic actual specimen thermal behaviour.
- Improves traceability and documentation for audits, quality systems and product qualification programs.
Related Standards
- IEC 60068-2-1 (Test A: Cold)
- IEC 60068-2-2 (Test B: Dry heat)
- IEC 60068-3-1, -3-5, -3-6 (supporting guidance)
- IEC 60584-1 (thermocouples), IEC 60751 (Pt100 sensors)
Keywords: IEC 60068-3-7, temperature chambers, environmental testing, Test A Cold, Test B Dry heat, chamber performance monitoring, artificial load, temperature sensors, air circulation.
Standards Content (Sample)
IEC 60068-3-7 ®
Edition 2.0 2020-07
REDLINE VERSION
INTERNATIONAL
STANDARD
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inside
Environmental testing –
Part 3-7: Supporting documentation and guidance – Measurements in
temperature chambers for tests A (Cold) and B (Dry heat) (with load)
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IEC 60068-3-7 ®
Edition 2.0 2020-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Environmental testing –
Part 3-7: Supporting documentation and guidance – Measurements in
temperature chambers for tests A (Cold) and B (Dry heat) (with load)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.040; 29.020 ISBN 978-2-8322-8641-8
– 2 – IEC 60068-3-7:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 2
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Measuring system . 8
4.1 General description . 8
4.2 Temperature . 8
4.2.1 General . 8
4.2.2 Temperature sensor . 9
4.3 Humidity . 9
4.3.1 General . 9
4.3.2 Humidity sensor . 9
4.4 Wall emissivity . 9
4.5 Air velocity . 9
4.5.1 General . 9
4.5.2 Air velocity sensor . 9
4.5.3 Air velocity sensor response time . 9
4.6 Recording device . 9
5 Determination of temperature performances . 9
5.1 Test area environment . 9
5.2 Chamber loading . 10
5.2.1 General . 10
5.2.2 Location of test load . 10
5.3 Installation of temperature sensors . 10
5.3.1 General . 10
5.3.2 Position of temperature sensors . 10
Position of wall sensors .
5.3.3 Position of load sensors. 10
6 Test procedures . 11
6.1 Confirmation methods . 11
6.1.1 General . 11
6.1.2 Test without load . 11
6.1.3 Test with load . 11
6.2 Routine monitoring methods . 11
7 Evaluation criteria . 12
8 Information to be given in the performance report . 12
Bibliography . 13
Figure 1 – Examples of artificial loads . 8
Figure 2 – Location of wall sensors .
Table 1 – Test conditions . 7
Table 2 – Artificial load – Values . 8
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change has
been made. Additions are in green text, deletions are in strikethrough red text.
– 4 – IEC 60068-3-7:2020 RLV © IEC 2020
International Standard IEC 60068-3-7 has been prepared by IEC technical committee TC 104:
Environmental conditions, classification and methods of test.
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) verbal forms have, in many parts, been changed to express requirements instead of
recommendations ('shall' instead of 'should');
b) Table 1 has been updated.
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/868/FDIS 104/873/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.
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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
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 great influence on test results. The physical characteristics of temperature
chambers can also influence test results.
– 6 – IEC 60068-3-7:2020 RLV © IEC 2020
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
1 Scope
This part of IEC 60068 provides specifies a uniform and reproducible method of confirming that
temperature test chambers conform to the requirements specified in the climatic test procedures
of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-
dissipating specimens under conditions which take into account air circulation inside the
working space of the chamber. This document is destined intended primarily 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 60068-2-1, Environmental testing – Part 2: Tests – Test A: Cold
IEC 60068-2-2, Basic environmental testing procedures – Part 2: Tests. Test B: Dry heat
IEC 60068-3-1, Basic environmental testing procedures – Part 3: Background information –
Section one: Cold and dry heat tests
IEC 60068-3-5:2018, Environmental testing – Part 3-5: Supporting documentation and guidance
– Confirmation of the performance of temperature chambers
IEC 60068-3-6, Environmental testing – Part 3-6: Supporting documentation and guidance –
Confirmation of the performance of temperature/humidity chambers
IEC 60584-1, Thermocouples – Part 1: Reference tables
IEC 60751, Industrial platinum resistance thermometer sensors
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
test specification
procedure applied to test chambers with or without forced air circulation, suitable for a wide
range of chamber sizes
Note 1 to entry: A summary of test conditions in IEC 60068-2-1 and IEC 60068-2-2 is given in Table 1; conditions
including sudden change of temperature have been removed from earlier versions of these documents.
Table 1 – Test conditions
Heat-dissipating Change of temperature
Temperature
Test
range
None With Sudden Gradual
Aa
–65 °C to +5 °C Ab
Ad
Ba
Bb
+30 °C to +400 °C Bc
Bd
Specimen heat- Specimen power status Change of Preferred air
dissipation temperature velocity
Temperature
Test
range
None With After Throughout Gradual High Low
stabilization test
Ab
🔾🔾 🔾🔾 🔾🔾
−65 °C to Ad
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+5 °C
Ae
🔾🔾 🔾🔾 🔾🔾 🔾🔾
Bb
🔾🔾 🔾🔾 🔾🔾
+30 °C to Bd
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+1 000 °C
Be
🔾🔾 🔾🔾 🔾🔾 🔾🔾
3.2
confirmation method (procedure 1)
specified method of making continuous measurements in order to establish whether the
performance of a test chamber conforms to the requirements detailed in IEC 60068-2-1, test A
and/or IEC 60068-2-2, test B
3.3
routine monitoring method (procedure 2)
specified method of making measurements, continuously or at intervals, to ensure that the test
chamber performance is being maintained
3.4
test load
test specimen that is installed in the test chamber for the confirmation measurements
Note 1 to entry: The test load is defined by geometric dimensions and by thermal properties.
– 8 – IEC 60068-3-7:2020 RLV © IEC 2020
3.5
artificial load
test load made in accordance with IEC 60068-3-7 with dimensions and thermal properties
related to the geometric dimensions and thermal capacity of the specimens intended to be
tested in the chamber
Note 1 to entry: Table 2 provides values for an artificial load and an example is given in Figure 1.
Table 2 – Artificial load – Values
Dimensions Volume approximately 20 % of working space
Heat transmission Approximately 10 kJ/m2K
Heat radiation emissivity > 0,7
Heat dissipation In accordance with
appendix C of IEC 60068-2-2:2007, 4.1.
Key
h height
l length
w width
s thickness of material
NOTE s = 3 mm stainless steel or 4 mm aluminium (h, l and w should be smaller than the relevant dimensions of
the working space).
Figure 1 – Examples of artificial loads
4 Measuring system
4.1 General description
The system used for the confirmation and routine monitoring measurements, either built-in or
independent of the chamber, should comply with the following requirements. Measurement
devices other than those listed may be used when their performance is shown to be technically
equivalent or when practical concerns require alternative techniques. Deviations from these
requirements shall be documented.
4.2 Temperature
4.2.1 General
Platinum resistance thermometers (in accordance with IEC 60751) or thermocouples (in
accordance with IEC 60584-1) should be used.
4.2.2 Temperature sensor
In a temperature range from −200 °C to +200 +650 °C the sensor measurement uncertainty
should be in accordance with class A of IEC 60751.
4.3 Humidity
4.3.1 General
The humidity test is required for confirmation of IEC 60068-2-2 tests only.
Place the independent humidity sensor as near as practical to the centre of the working space.
Types of humidity monitoring sensors are described in 4.34 of IEC 60068-3-6:2018.
4.3.2 Humidity sensor
Sensor measurement uncertainty should not exceed ±3 % RH.
4.4 Wall emissivity
Emissivity of the chamber enclosure should be in accordance with table IV of appendix J of
IEC 60068-3-1.
4.5 Air velocity
4.5.1 General
An airflow sensor should be installed such that the maximum air velocity impinging on the load
can be monitored.
4.5.2 Air velocity sensor
The air velocity sensor measurement uncertainty should be compatible with IEC 60068-2-1 and
60068-2-2 tolerances.
4.5.3 Air velocity sensor response time
The air velocity sensor response time should be greater than 5 s to avoid any influence on it by
airflow fluctuation.
4.6 Recording device
For confirmation monitoring, data should be recorded at least once per minute. For routine
monitoring, data should be recorded at least once every 5 min. For the purpose of chamber
verification, the device utilized for recording data from the chamber monitoring sensors should
be independent of the chamber control system.
5 Determination of temperature performances
5.1 Test area environment
The environment in the test area shall be in accordance with 4.1 of IEC 60068-3-5:2018.
– 10 – IEC 60068-3-7:2020 RLV © IEC 2020
5.2 Chamber loading
5.2.1 General
Provision is made for measurement of test chamber performance with different loading
conditions.
Test loads: heat-dissipating
non heat-dissipating
Artificial loads: heat-dissipating
non heat-dissipating
NOTE However, when testing large, high heat dissipating specimens, it may can be desirable to allow the specimen
to develop thermal gradients by using 'free air' chambers or those with a low airflow (typically less than 1 0,5 m/s).
In such cases it is possible that the chamber may will not have a uniform temperature within the working space and
it is necessary important to monitor the temperatures of the air entering and exiting the specimen.
5.2.2 Location of test load
The test load should always shall be located in the enclosure so that it is entirely within the
working space.
For heat dissipating multiple loads, heating effects should be minimized in accordance with the
following subclauses of IEC 60068-2-2:
no forced air circulation 29.1.1.2 and 40.1.1.2,
forced air circulation 29.1.2.2 and 40.1.2.2.
When testing multiple heat dissipating specimens, any heating effects between specimens and
on the overall chamber temperature gradient shall be minimized.
5.3 Installation of temperature sensors
5.3.1 General
The temperature sensors should shall be protected from heating and cooling sources and from
direct heat radiation. In addition, the wall and load sensors should shall be protected from
convection heat transfer from the surrounding air by suitable insulation.
5.3.2 Position of temperature sensors
Position of temperature sensors shall be in accordance with 4.4 of IEC 60068-3-5:2018.
5.3.2 Position of wall sensors
When chamber walls are directly heated and/or cooled, additional sensors located in
accordance with figure 2 are necessary.
IEC 1552/01
Figure 2 – Location of wall sensors
5.3.3 Position of load sensors
Test load temperature sensors should shall be positioned on representative points of the load
to indicate that temperature stability is reached.
6 Test procedures
6.1 Confirmation methods
6.1.1 General
Tests should shall be conducted at temperatures and with loads which are representative of the
intended use of the chamber.
6.1.2 Test without load
Tests without load shall be conducted in accordance with IEC 60068-3-5.
6.1.3 Test with load
– Install and operate the test load.
– Repeat test sequence as in 6.1.2 above.
6.2 Routine monitoring methods
Routine monitoring should shall be conducted at regular intervals for control purposes.
Additional monitoring should shall be conducted whenever the chamber undergoes
repair/maintenance to the heating/cooling system, the air circulating system or to the chamber
control system. Sensors used for routine monitoring should be selected from locations identified
in 4.4 of IEC 60068-3-5:2018.
Monitor the temperature at the selected points at 5 min intervals or more frequently.
Routine monitoring is used to determine that the chamber is working within its tolerances for a
given test load. However, the temperature tolerance on a single monitoring point will be different
from that given for confirmation monitoring, i.e. ±1,5 K (cold test) and ±1,0 K (dry heat test).
– 12 – IEC 60068-3-7:2020 RLV © IEC 2020
7 Evaluation criteria
The performance of the temperature test chamber is confirmed if all results are within the
specification limits of the appropriate part of the IEC 60068-2 series.
8 Information to be given in the performance report
As a minimum, the test report shall contain the following information:
– Atmospheric conditions (temperature and relative humidity) in the test area.
– Size and volume of chamber enclosure and working space.
– Temperature fluctuation, temperature gradient, and temperature gradient variation in space
at each temperature stage of Clause 5 of IEC 60068-3-5:2018.
– Temperature rate of change, heating and/or cooling.
– Temperature extremes.
– Any deviations such as overshoot.
– Details of test load.
– Details of data acquisition system.
– Air flow speed.
– Evaluation of measurement uncertainties.
Bibliography
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-3-1, Environmental testing – Part 3-1: Supporting documentation and guidance –
Cold and dry heat tests
IEC 60068-3-6:2018, Environmental testing – Part 3-6: Supporting documentation and guidance
– Confirmation of the performance of temperature/humidity chambers
IEC 60584-1, Thermocouples – Part 1: EMF specifications and tolerances
IEC 60751, Industrial platinum resistance thermometers and platinum temperature sensors
___________
IEC 60068-3-7 ®
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 3-7: Supporting documentation and guidance – Measurements in
temperature chambers for tests A (Cold) and B (Dry heat) (with load)
Essais d'environnement –
Partie 3-7: Documentation d'accompagnement et recommandations –
Mesurages dans les chambres d'essai en température pour les essais A (froid)
et B (chaleur sèche) (avec charge)
– 2 – IEC 60068-3-7:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Measuring system . 8
4.1 General description . 8
4.2 Temperature . 8
4.2.1 General . 8
4.2.2 Temperature sensor . 8
4.3 Humidity . 8
4.3.1 General . 8
4.3.2 Humidity sensor . 9
4.4 Wall emissivity . 9
4.5 Air velocity . 9
4.5.1 General . 9
4.5.2 Air velocity sensor . 9
4.5.3 Air velocity sensor response time . 9
4.6 Recording device . 9
5 Determination of temperature performances . 9
5.1 Test area environment . 9
5.2 Chamber loading . 9
5.2.1 General . 9
5.2.2 Location of test load . 10
5.3 Installation of temperature sensors . 10
5.3.1 General . 10
5.3.2 Position of temperature sensors . 10
5.3.3 Position of load sensors. 10
6 Test procedures . 10
6.1 Confirmation methods . 10
6.1.1 General . 10
6.1.2 Test without load . 10
6.1.3 Test with load . 10
6.2 Routine monitoring methods . 10
7 Evaluation criteria . 11
8 Information to be given in the performance report . 11
Bibliography . 12
Figure 1 – Examples of artificial loads . 8
Table 1 – Test conditions . 7
Table 2 – Artificial load – Values . 7
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
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 60068-3-7 has been prepared by IEC technical committee TC 104:
Environmental conditions, classification and methods of test.
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) verbal forms have, in many parts, been changed to express requirements instead of
recommendations ('shall' instead of 'should');
b) Table 1 has been updated.
– 4 – IEC 60068-3-7:2020 © IEC 2020
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/868/FDIS 104/873/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.
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.
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 great influence on test results. The physical characteristics of temperature
chambers can also influence test results.
– 6 – IEC 60068-3-7:2020 © IEC 2020
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
1 Scope
This part of IEC 60068 specifies a uniform and reproducible method of confirming that
temperature test chambers conform to the requirements specified in the climatic test procedures
of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-
dissipating specimens under conditions which take into account air circulation inside the
working space of the chamber. This document is intended primarily 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 60068-3-5:2018, Environmental testing – Part 3-5: Supporting documentation and guidance
– Confirmation of the performance of temperature 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
test specification
procedure applied to test chambers with or without forced air circulation, suitable for a wide
range of chamber sizes
Note 1 to entry: A summary of test conditions in IEC 60068-2-1 and IEC 60068-2-2 is given in Table 1; conditions
including sudden change of temperature have been removed from earlier versions of these documents.
Table 1 – Test conditions
Specimen heat- Specimen power status Change of Preferred air
dissipation temperature velocity
Temperature
Test
range
None With After Throughout Gradual High Low
stabilization test
Ab
🔾🔾 🔾🔾 🔾🔾
−65 °C to Ad
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+5 °C
Ae
🔾🔾 🔾🔾 🔾🔾 🔾🔾
Bb
🔾🔾 🔾🔾 🔾🔾
+30 °C to Bd
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+1 000 °C
Be
🔾🔾 🔾🔾 🔾🔾 🔾🔾
3.2
confirmation method
specified method of making continuous measurements in order to establish whether the
performance of a test chamber conforms to the requirements detailed in IEC 60068-2-1, test A
and/or IEC 60068-2-2, test B
3.3
routine monitoring method
specified method of making measurements, continuously or at intervals, to ensure that the test
chamber performance is being maintained
3.4
test load
test specimen that is installed in the test chamber for the confirmation measurements
Note 1 to entry: The test load is defined by geometric dimensions and by thermal properties.
3.5
artificial load
test load made in accordance with IEC 60068-3-7 with dimensions and thermal properties
related to the geometric dimensions and thermal capacity of the specimens intended to be
tested in the chamber
Note 1 to entry: Table 2 provides values for an artificial load and an example is given in Figure 1.
Table 2 – Artificial load – Values
Dimensions Volume approximately 20 % of working space
Heat transmission Approximately 10 kJ/m2K
Heat radiation emissivity > 0,7
In accordance with
Heat dissipation
IEC 60068-2-2:2007, 4.1.
– 8 – IEC 60068-3-7:2020 © IEC 2020
Key
h height
l length
w width
s thickness of material
NOTE s = 3 mm stainless steel or 4 mm aluminium (h, l and w should be smaller than the relevant dimensions of
the working space).
Figure 1 – Examples of artificial loads
4 Measuring system
4.1 General description
The system used for the confirmation and routine monitoring measurements, either built-in or
independent of the chamber, should comply with the following requirements. Measurement
devices other than those listed may be used when their performance is shown to be technically
equivalent or when practical concerns require alternative techniques. Deviations from these
requirements shall be documented.
4.2 Temperature
4.2.1 General
Platinum resistance thermometers (in accordance with IEC 60751) or thermocouples (in
accordance with IEC 60584-1) should be used.
4.2.2 Temperature sensor
In a temperature range from −200 °C to +650 °C the sensor measurement uncertainty should
be in accordance with class A of IEC 60751.
4.3 Humidity
4.3.1 General
The humidity test is required for confirmation of IEC 60068-2-2 tests only.
Place the independent humidity sensor as near as practical to the centre of the working space.
Types of humidity monitoring sensors are described in 4.4 of IEC 60068-3-6:2018.
4.3.2 Humidity sensor
Sensor measurement uncertainty should not exceed ±3 % RH.
4.4 Wall emissivity
Emissivity of the chamber enclosure should be in accordance with IEC 60068-3-1.
4.5 Air velocity
4.5.1 General
An airflow sensor should be installed such that the maximum air velocity impinging on the load
can be monitored.
4.5.2 Air velocity sensor
The air velocity sensor measurement uncertainty should be compatible with IEC 60068-2-1 and
60068-2-2 tolerances.
4.5.3 Air velocity sensor response time
The air velocity sensor response time should be greater than 5 s to avoid any influence on it by
airflow fluctuation.
4.6 Recording device
For confirmation monitoring, data should be recorded at least once per minute. For routine
monitoring, data should be recorded at least once every 5 min. For the purpose of chamber
verification, the device utilized f
...
IEC 60068-3-7 ®
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 3-7: Supporting documentation and guidance – Measurements in
temperature chambers for tests A (Cold) and B (Dry heat) (with load)
Essais d'environnement –
Partie 3-7: Documentation d'accompagnement et recommandations –
Mesurages dans les chambres d'essai en température pour les essais A (froid)
et B (chaleur sèche) (avec charge)
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IEC 60068-3-7 ®
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 3-7: Supporting documentation and guidance – Measurements in
temperature chambers for tests A (Cold) and B (Dry heat) (with load)
Essais d'environnement –
Partie 3-7: Documentation d'accompagnement et recommandations –
Mesurages dans les chambres d'essai en température pour les essais A (froid)
et B (chaleur sèche) (avec charge)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040; 29.020 ISBN 978-2-8322-8599-2
– 2 – IEC 60068-3-7:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Measuring system . 8
4.1 General description . 8
4.2 Temperature . 8
4.2.1 General . 8
4.2.2 Temperature sensor . 8
4.3 Humidity . 8
4.3.1 General . 8
4.3.2 Humidity sensor . 9
4.4 Wall emissivity . 9
4.5 Air velocity . 9
4.5.1 General . 9
4.5.2 Air velocity sensor . 9
4.5.3 Air velocity sensor response time . 9
4.6 Recording device . 9
5 Determination of temperature performances . 9
5.1 Test area environment . 9
5.2 Chamber loading . 9
5.2.1 General . 9
5.2.2 Location of test load . 10
5.3 Installation of temperature sensors . 10
5.3.1 General . 10
5.3.2 Position of temperature sensors . 10
5.3.3 Position of load sensors. 10
6 Test procedures . 10
6.1 Confirmation methods . 10
6.1.1 General . 10
6.1.2 Test without load . 10
6.1.3 Test with load . 10
6.2 Routine monitoring methods . 10
7 Evaluation criteria . 11
8 Information to be given in the performance report . 11
Bibliography . 12
Figure 1 – Examples of artificial loads . 8
Table 1 – Test conditions . 7
Table 2 – Artificial load – Values . 7
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 60068-3-7 has been prepared by IEC technical committee TC 104:
Environmental conditions, classification and methods of test.
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) verbal forms have, in many parts, been changed to express requirements instead of
recommendations ('shall' instead of 'should');
b) Table 1 has been updated.
– 4 – IEC 60068-3-7:2020 © IEC 2020
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/868/FDIS 104/873/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.
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.
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 great influence on test results. The physical characteristics of temperature
chambers can also influence test results.
– 6 – IEC 60068-3-7:2020 © IEC 2020
ENVIRONMENTAL TESTING –
Part 3-7: Supporting documentation and guidance –
Measurements in temperature chambers for
tests A (Cold) and B (Dry heat) (with load)
1 Scope
This part of IEC 60068 specifies a uniform and reproducible method of confirming that
temperature test chambers conform to the requirements specified in the climatic test procedures
of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-
dissipating specimens under conditions which take into account air circulation inside the
working space of the chamber. This document is intended primarily 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 60068-3-5:2018, Environmental testing – Part 3-5: Supporting documentation and guidance
– Confirmation of the performance of temperature 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
test specification
procedure applied to test chambers with or without forced air circulation, suitable for a wide
range of chamber sizes
Note 1 to entry: A summary of test conditions in IEC 60068-2-1 and IEC 60068-2-2 is given in Table 1; conditions
including sudden change of temperature have been removed from earlier versions of these documents.
Table 1 – Test conditions
Specimen heat- Specimen power status Change of Preferred air
dissipation temperature velocity
Temperature
Test
range
None With After Throughout Gradual High Low
stabilization test
Ab
🔾🔾 🔾🔾 🔾🔾
−65 °C to Ad
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+5 °C
Ae
🔾🔾 🔾🔾 🔾🔾 🔾🔾
Bb
🔾🔾 🔾🔾 🔾🔾
+30 °C to Bd
🔾🔾 🔾🔾 🔾🔾 🔾🔾
+1 000 °C
Be
🔾🔾 🔾🔾 🔾🔾 🔾🔾
3.2
confirmation method
specified method of making continuous measurements in order to establish whether the
performance of a test chamber conforms to the requirements detailed in IEC 60068-2-1, test A
and/or IEC 60068-2-2, test B
3.3
routine monitoring method
specified method of making measurements, continuously or at intervals, to ensure that the test
chamber performance is being maintained
3.4
test load
test specimen that is installed in the test chamber for the confirmation measurements
Note 1 to entry: The test load is defined by geometric dimensions and by thermal properties.
3.5
artificial load
test load made in accordance with IEC 60068-3-7 with dimensions and thermal properties
related to the geometric dimensions and thermal capacity of the specimens intended to be
tested in the chamber
Note 1 to entry: Table 2 provides values for an artificial load and an example is given in Figure 1.
Table 2 – Artificial load – Values
Dimensions Volume approximately 20 % of working space
Heat transmission Approximately 10 kJ/m2K
Heat radiation emissivity > 0,7
In accordance with
Heat dissipation
IEC 60068-2-2:2007, 4.1.
– 8 – IEC 60068-3-7:2020 © IEC 2020
Key
h height
l length
w width
s thickness of material
NOTE s = 3 mm stainless steel or 4 mm aluminium (h, l and w should be smaller than the relevant dimensions of
the working space).
Figure 1 – Examples of artificial loads
4 Measuring system
4.1 General description
The system used for the confirmation and routine monitoring measurements, either built-in or
independent of the chamber, should comply with the following requirements. Measurement
devices other than those listed may be used when their performance is shown to be technically
equivalent or when practical concerns require alternative techniques. Deviations from these
requirements shall be documented.
4.2 Temperature
4.2.1 General
Platinum resistance thermometers (in accordance with IEC 60751) or thermocouples (in
accordance with IEC 60584-1) should be used.
4.2.2 Temperature sensor
In a temperature range from −200 °C to +650 °C the sensor measurement uncertainty should
be in accordance with class A of IEC 60751.
4.3 Humidity
4.3.1 General
The humidity test is required for confirmation of IEC 60068-2-2 tests only.
Place the independent humidity sensor as near as practical to the centre of the working space.
Types of humidity monitoring sensors are described in 4.4 of IEC 60068-3-6:2018.
4.3.2 Humidity sensor
Sensor measurement uncertainty should not exceed ±3 % RH.
4.4 Wall emissivity
Emissivity of the chamber enclosure should be in accordance with IEC 60068-3-1.
4.5 Air velocity
4.5.1 General
An airflow sensor should be installed such that the maximum air velocity impinging on the load
can be monitored.
4.5.2 Air velocity sensor
The air velocity sensor measurement uncertainty should be compatible with IEC 60068-2-1 and
60068-2-2 tolerances.
4.5.3 Air velocity sensor response time
The air velocity sensor response time should be greater than 5 s to avoid any influence on it by
airflow fluctuation.
4.6 Recording device
For confirmation monitoring, data should be recorded at least once per minute. For routine
monitoring, data should be recorded at least once every 5 min. For the purpose of chamber
verification, the device utilized for recording data should be independent of the chamber control
system.
5 Determination of temperature performances
5.1 Test area environment
The environment in the test area shall be in accordance with 4.1 of IEC 60068-3-5:2018.
5.2 Chamber loading
5.2.1 General
Provision is made for measurement of test chamber performance with different loading
conditions.
Test loads: heat-dissipating
non heat-dissipating
Artificial loads: heat-dissipating
non heat-dissipating
NOTE However, when testing large, high heat dissipating specimens, it can be desirable to allow the specimen to
develop thermal gradients by using 'free air' chambers or those with a low airflow (typically less than 0,5 m/s). In
such cases it is possible that the chamber will not have a uniform temperature within the working space and it is
important to monitor the temperatures of the air entering and exiting the specimen.
– 10 – IEC 60068-3-7:2020 © IEC 2020
5.2.2 Location of test load
The test load shall be located in the enclosure so that it is entirely within the working space.
When testing multiple heat dissipating specimens, any heating effects between specimens and
on the overall chamber temperature gradient shall be minimized.
5.3 Installation of temperature sensors
5.3.1 General
The temperature sensors shall be protected from heating and cooling sources and from direct
heat radiation. In addition, the wall and load sensors shall be protected from convection heat
transfer from the surrounding air by suitable insulation.
5.3.2 Position of temperature sensors
Position of temperature sensors shall be in accordance with 4.4 of IEC 60068-3-5:2018.
5.3.3 Position of load sensors
Test load temperature sensors shall be positioned on representative points of the load to
indicate that temperature stability is reached.
6 Test procedures
6.1 Confirmation methods
6.1.1 General
Tests shall be conducted at temperatures and with loads which are representative of the
intended use of the chamber.
6.1.2 Test without load
Tests without load shall be conducted in accordance with IEC 60068-3-5.
6.1.3 Test with load
– Install and operate the test load.
– Repeat test sequence as in 6.1.2 above.
6.2 Routine monitoring methods
Routine monitoring shall be conducted at regular intervals for control purposes. Additional
monitoring shall be conducted whenever the chamber undergoes repair/maintenance to the
heating/cooling system, the air circulating system or to the chamber control system. Sensors
used for routine monitoring should be selected from locations identified in 4.4 of
IEC 60068-3-5:2018.
Monitor the temperature at the selected points at 5 min intervals or more frequently.
Routine monitoring is used to determine that the chamber is working within its tolerances for a
given test load. However, the temperature tolerance on a single monitoring point will be different
fro
...
Frequently Asked Questions
IEC 60068-3-7:2020 is a standard published by the International Electrotechnical Commission (IEC). Its full title is "Environmental testing - Part 3-7: Supporting documentation and guidance - Measurements in temperature chambers for tests A (Cold) and B (Dry heat) (with load)". This standard covers: IEC 60068-3-7:2020 specifies a uniform and reproducible method of confirming that temperature test chambers conform to the requirements specified in the climatic test procedures of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-dissipating specimens under conditions which take into account air circulation inside the working space of the chamber. This document is intended primarily for users when conducting regular chamber performance monitoring. 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: - verbal forms have, in many parts, been changed to express requirements instead of recommendations ('shall' instead of 'should'); - Table 1 has been updated.
IEC 60068-3-7:2020 specifies a uniform and reproducible method of confirming that temperature test chambers conform to the requirements specified in the climatic test procedures of IEC 60068-2-1 and IEC 60068-2-2, when loaded with either heat-dissipating or non heat-dissipating specimens under conditions which take into account air circulation inside the working space of the chamber. This document is intended primarily for users when conducting regular chamber performance monitoring. 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: - verbal forms have, in many parts, been changed to express requirements instead of recommendations ('shall' instead of 'should'); - Table 1 has been updated.
IEC 60068-3-7:2020 is classified under the following ICS (International Classification for Standards) categories: 19.040 - Environmental testing; 29.020 - Electrical engineering in general. The ICS classification helps identify the subject area and facilitates finding related standards.
IEC 60068-3-7:2020 has the following relationships with other standards: It is inter standard links to IEC 60068-3-7:2001. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
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