EN IEC 60721-2-4:2018

SLOVENSKI STANDARD
01-november-2018
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Classification of environmental conditions - Part 2-4: Environmental conditions appearing
in nature - Solar radiation and temperature (IEC 60721-2-4:2018)
Classification des conditions d'environnement - Partie 2-4: Conditions d'environnement
présentes dans la nature - Rayonnement solaire et température (IEC 60721-2-4:2018)
Ta slovenski standard je istoveten z: EN IEC 60721-2-4:2018
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60721-2-4

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2018
ICS 19.040
English Version
Classification of environmental conditions - Part 2-4:
Environmental conditions appearing in nature - Solar radiation
and temperature
(IEC 60721-2-4:2018)
Classification des conditions d'environnement - Partie 2-4: Klassifizierung von Umgebungsbedingungen - Teil 2-4:
Conditions d'environnement présentes dans la nature - Natürliche Umgebungsbedingungen - Sonnenstrahlung und
Rayonnement solaire et température Temperatur
(IEC 60721-2-4:2018) (IEC 60721-2-4:2018)
This European Standard was approved by CENELEC on 2018-07-27. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60721-2-4:2018 E

European foreword
The text of document 104/800/FDIS, future edition 2 of IEC 60721-2-4, prepared by IEC/TC 104
"Environmental conditions, classification and methods of test" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN IEC 60721-2-4:2018.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2019-04-27
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2021-07-27
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 60721-2-4:2018 was approved by CENELEC as a
European Standard without any modification.

IEC 60721-2-4 ®
Edition 2.0 2018-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Classification of environmental conditions –

Part 2-4: Environmental conditions appearing in nature – Solar radiation and

temperature
Classification des conditions d’environnement –

Partie 2-4: Conditions d'environnement présentes dans la nature – Rayonnement

solaire et température
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-5781-4

– 2 – IEC 60721-2-4:2018 © IEC 2018
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 General . 5
5 Solar radiation physics . 6
6 Levels of global radiation . 7
6.1 Maximum levels . 7
6.2 Mean monthly and annual global solar radiation . 7
6.3 Simultaneous values of maximum air temperatures and solar radiation . 8
6.4 World distribution of daily global irradiation . 8
7 Minimum levels of atmospheric radiation at night . 8
Annex A (informative) World distribution of daily global irradiation . 10
Bibliography . 15

Figure 1 – Spectra of electromagnetic radiation from the Sun and the surface
of the Earth . 9
Figure A.1 – Mean relative global irradiation for the month of June (in %) . 12
Figure A.2 – Mean relative global irradiation for the month of December (in %) . 13
Figure A.3 – Mean relative global irradiation for the year (in %) . 14

Table 1 – Typical peak values of global irradiance (in W/m from a cloudless sky) . 7
Table A.1 – Mean daily extra-terrestrial global irradiation (kWh/m ) . 11

IEC 60721-2-4:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 2-4: Environmental conditions appearing in nature –
Solar radiation and temperature

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 60721-2-4 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
This second edition cancels and replaces the first edition published in 1987 and
Amendment 1:1988. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Figures updated including the addition of global irradiation information,
b) Format updated.
– 4 – IEC 60721-2-4:2018 © IEC 2018
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/800/FDIS 104/803/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 60721 series, published under the general title Classification of
environmental conditions, 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.
IEC 60721-2-4:2018 © IEC 2018 – 5 –
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 2-4: Environmental conditions appearing in nature –
Solar radiation and temperature

1 Scope
This part of IEC 60721 presents a broad division into types of solar radiation areas. It is
intended to be used as part of the background material when selecting appropriate severities
of solar radiation for product applications.
All types of geographical areas are covered, except areas with altitudes above 5 000 m.
This document also serves to define limiting severities of solar radiation to which products are
liable to be exposed during transportation, storage and use.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 General
Solar radiation can affect products primarily by the heating of material and their environment
or by photochemical degradation of material.
Solar radiation, especially its ultraviolet content, causes photochemical degradation of most
organic materials. Elasticity and plasticity of certain rubber compounds and plastic materials
are affected. Optical glass may become opaque.
Solar radiation bleaches out colours in paints, textiles, paper, etc. This can be of importance,
for example for the colour-coding of components.
The heating of material is a consequence of exposure to solar radiation. The presentation of
severities of solar radiation is therefore related to the power density radiated towards a
surface, or irradiance, expressed in W/m .
An object subjected to solar radiation will attain a temperature that depends primarily on the
surrounding air temperature, the energy radiated from the Sun,
...