IEC 60068-3-7:2020

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 is available as IEC 60068-3-7:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
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)

IEC 60068-3-7:2020 est disponible sous forme de IEC 60068-3-7:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
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.

Standards Content (sample)

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)
IEC 60068-3-7:2020-07(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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

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 60068-3-7:2020 © 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

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IEC 60068-3-7:2020 © IEC 2020 – 3 –
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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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.
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– 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.
---------------------- Page: 6 ----------------------
IEC 60068-3-7:2020 © IEC 2020 – 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 great influence on test results. The physical characteristics of temperature

chambers can also influence test results.
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– 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.

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IEC 60068-3-7:2020 © IEC 2020 – 7 –
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.
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– 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.
---------------------- Page: 10 ----------------------
IEC 60068-3-7:2020 © IEC 2020 – 9 –
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.

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– 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

from that given for confirmation monitoring, i.e. ±1,5 K (cold test) and ±1,0 K (dry heat test).

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IEC 60068-3-7:2020 © IEC 2020 – 11 –
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 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.
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– 12 – IEC 60068-3-7:2020 © IEC 2020
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

___________
---------------------- Page: 14 ----------------------
– 14 – IEC 60068-3-7:2020 © IEC 2020
SOMMAIRE

AVANT-PROPOS .................................................................................................................. 15

INTRODUCTION ................................................................................................................... 17

1 Domaine d'application ................................................................................................... 18

2 Références normatives .................................................................................................. 18

3 Termes et définitions ..................................................................................................... 18

4 Système de mesure ....................................................................................................... 20

4.1 Description générale ............................................................................................. 20

4.2 Température ......................................................................................................... 20

4.2.1 Généralités .................................................................................................... 20

4.2.2 Capteur de température ................................................................................. 20

4.3 Humidité ............................................................................................................... 20

4.3.1 Généralités .................................................................................................... 20

4.3.2 Capteur d'humidité......................................................................................... 21

4.4 Pouvoir émissif des parois .................................................................................... 21

4.5 Vitess
...