IEC 60721-3-3:2019
(Main)Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
IEC 60721-3-3:2019 classifies groups of environmental parameters and their severities to which products are subjected when installed for stationary use at weatherprotected locations.
This third edition cancels and replaces the second edition published in 1994, Amendment 1: 1995 and Amendment 2:1996. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) Clause 3: definitions aligned with IEC 60721-3-1.
b) Clause 4: aligned with IEC 60721-3-1.
c) Clause 5: Clause A.3 has been incorporated into Clause 5.
d) Subclause 5.2: all existing climate classes have been replaced by completely new classes. The new classes are divided into two groups. The reason for the new classes is the latest revision of IEC 60721-2-1 which incorporates new climate types.
e) Subclause 5.3: addition of a new class for low air pressure.
f) Defined values of chemically active substances are now by reference to ISO 9223.
g) Subclause 5.6: all existing classes for mechanically active substances have been replaced by completely new classes, in alignment with IEC 60721-3-1.
h) Subclause 5.7: all existing classes for mechanical conditions have been replaced by completely new classes, in alignment with IEC 60721-3-1.
i) Table 1: new climatic classes with new severities.
j) Table 2: new class for low air pressure.
k) Table 4: new mechanically active substances classes.
l) Table 5: new mechanical conditions classes.
m) Annex A: revised and includes a clean climatogram.
n) Annex B: revised and includes the definition of seismic environment.
o) All classes regarding fire, all combined classes, all chemically active substances classes, Clause A.2, Annexes C, D and E have been removed.
Classification des conditions d'environnement - Partie 3-3: Classification des groupements des agents d'environnement et de leurs sévérités - Utilisation à poste fixe, protégé contre les intempéries
L’IEC 60721-3-3:2019 classifie les groupements d’agents d’environnement et leurs sévérités, auxquels sont soumis des produits montés pour une utilisation à poste fixe dans des emplacements protégés contre les intempéries.
Cette troisième édition annule et remplace la deuxième édition parue en 1994, ainsi que son amendement 1:1995 et son amendement 2:1996. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) Article 3: alignement des définitions sur l’IEC 60721-3-1.
b) Article 4: alignement sur l’IEC 60721-3-1.
c) Article 5: intégration de l'Article A.3 dans l’Article 5.
d) Paragraphe 5.2: toutes les catégories climatiques ont été remplacées par des catégories totalement nouvelles. Ces nouvelles catégories sont divisées en deux groupes. La création de nouvelles catégories est justifiée par la dernière révision de l’IEC 60721-2-1 qui intègre de nouveaux types de climats.
e) Paragraphe 5.3: ajout d'une nouvelle catégorie pour la basse pression atmosphérique.
f) Les valeurs définies des substances chimiquement actives font désormais référence à l’ISO 9223.
g) Paragraphe 5.6: toutes les catégories existantes pour les substances mécaniquement actives ont été remplacées par des catégories totalement nouvelles, avec alignement sur l’IEC 60721-3-1.
h) Paragraphe 5.7: toutes les catégories existantes pour les conditions mécaniques ont été remplacées par des catégories totalement nouvelles, avec alignement sur l’IEC 60721-3-1.
i) Tableau 1: nouvelles catégories climatiques avec de nouvelles sévérités.
j) Tableau 2: nouvelle catégorie pour la basse pression atmosphérique.
k) Tableau 4: nouvelles catégories pour les substances mécaniquement actives.
l) Tableau 5: nouvelles catégories pour les conditions mécaniques.
m) Annexe A: révision et introduction d'un climatogramme propre.
n) Annexe B: révision et introduction de la définition de l'environnement sismique.
o) Toutes les catégories relatives au feu, toutes les catégories combinées, toutes les catégories des substances chimiquement actives, l'Article A.2, les Annexes C, D et E ont été supprimés.
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Standards Content (Sample)
IEC 60721-3-3 ®
Edition 3.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Classification of environmental conditions –
Part 3-3: Classification of groups of environmental parameters
and their severities – Stationary use at weatherprotected locations
Classification des conditions d'environnement –
Partie 3-3: Classification des groupements des agents d'environnement et de
leurs sévérités – Utilisation à poste fixe, protégé contre les intempéries
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IEC 60721-3-3 ®
Edition 3.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Classification of environmental conditions –
Part 3-3: Classification of groups of environmental parameters
and their severities – Stationary use at weatherprotected locations
Classification des conditions d'environnement –
Partie 3-3: Classification des groupements des agents d'environnement et de
leurs sévérités – Utilisation à poste fixe, protégé contre les intempéries
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-6954-1
– 2 – IEC 60721-3-3:2019 © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions. 5
4 General . 6
5 Classification of groups of environmental parameters and their severities . 7
5.1 General . 7
5.2 Climatic conditions (K) . 7
5.3 Special climatic conditions (Z) . 8
5.4 Biological conditions (B) . 8
5.5 Chemically active substances (C) . 8
5.6 Mechanically active substances (S) . 8
5.7 Mechanical conditions (M) . 9
Annex A (informative) Interdependence of air temperature, relative air humidity, and
absolute air humidity . 11
Annex B (informative) Definition of seismic environment . 12
Bibliography . 14
Figure A.1 – Climatogram of interdependence of air temperature, relative air humidity,
and absolute air humidity . 11
Table 1 – Classification of climatic conditions . 9
Table 2 – Classification of special climatic conditions . 10
Table 3 – Classification of biological conditions . 10
Table 4 − Classification of mechanically active substances . 10
Table 5 − Classification of mechanical conditions . 10
Table B.1 – Correlation of seismic zones with expected magnitudes . 13
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –
Part 3-3: Classification of groups of environmental parameters
and their severities – Stationary use at weatherprotected locations
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60721-3-3 has been prepared by IEC technical committee 104:
Environmental conditions, classification, and methods of test.
This third edition cancels and replaces the second edition published in 1994, Amendment 1:
1995 and Amendment 2:1996. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Clause 3: definitions aligned with IEC 60721-3-1.
b) Clause 4: aligned with IEC 60721-3-1.
c) Clause 5: Clause A.3 has been incorporated into Clause 5.
– 4 – IEC 60721-3-3:2019 © IEC 2019
d) Subclause 5.2: all existing climate classes have been replaced by completely new classes.
The new classes are divided into two groups. The reason for the new classes is the latest
revision of IEC 60721-2-1 which incorporates new climate types.
e) Subclause 5.3: addition of a new class for low air pressure.
f) Defined values of chemically active substances are now by reference to ISO 9223.
g) Subclause 5.6: all existing classes for mechanically active substances have been replaced
by completely new classes, in alignment with IEC 60721-3-1.
h) Subclause 5.7: all existing classes for mechanical conditions have been replaced by
completely new classes, in alignment with IEC 60721-3-1.
i) Table 1: new climatic classes with new severities.
j) Table 2: new class for low air pressure.
k) Table 4: new mechanically active substances classes.
l) Table 5: new mechanical conditions classes.
m) Annex A: revised and includes a clean climatogram.
n) Annex B: revised and includes the definition of seismic environment.
o) All classes regarding fire, all combined classes, all chemically active substances classes,
Clause A.2, Annexes C, D and E have been removed.
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/829/FDIS 104/837/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.
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –
Part 3-3: Classification of groups of environmental parameters
and their severities – Stationary use at weatherprotected locations
1 Scope
This part of IEC 60721 classifies groups of environmental parameters and their severities to
which products are subjected when installed for stationary use at weatherprotected locations.
The environmental conditions specified in this document are limited to those which can directly
affect the performance of products. Only environmental conditions as such are considered. No
special description of the effects of these conditions on the products is provided.
Environmental conditions directly related to explosion hazards, microclimate within a product,
fire extinction and ionizing radiation are excluded. Any other unforeseen incidents are also
excluded. The possibility of their occurrence can be considered as special cases. This
document does not cover equipment covered by building standards, codes or regulations.
Conditions of stationary use at non-weatherprotected locations, portable and non-stationary
use, use in vehicles and ships, conditions of storage and transportation, and microclimates
inside products are given in other parts of the IEC 60721-3 series.
A limited number of classes of environmental conditions is given, covering a broad field of
applications.
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 60721-3-0, Classification of environmental conditions − Part 3: Classification of groups of
environmental parameters and their severities − Introduction
IEC 60721-1, Classification of environmental conditions − Part 1: Environmental parameters
and their severities
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60721-1 and the
following 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
– 6 – IEC 60721-3-3:2019 © IEC 2019
3.1
stationary use
use of a product mounted firmly on a structure, or permanently placed at a certain site
3.2
weatherprotected location
location at which a product is protected from direct exposure to meteorological conditions
4 General
A product may be subjected to a range of environmental conditions during its lifetime. These
conditions have been separated into classes described in IEC 60721-3-0. The classes given
may be used for defining the maximum short-term environmental stresses of a product.
However, they do not provide information regarding the long-term or total lifetime
environmental stresses a product may experience. This means that no reliability or lifetime
assessment is possible based on these classes alone. Refer to IEC 60721-2 (all parts) and
applicable technical reports (IEC TR 62130 and IEC TR 62131-5) for further information on
actual environmental conditions.
A product will be simultaneously exposed to a number of environmental parameters, for
example, low air pressure and temperature, temperature and humidity, as well as vibration and
temperature change. Combinations of the environmental parameters given may increase the
effect on a product. Therefore, combined conditions should be considered in the design and
evaluation of a product.
Products should be designed to survive and operate in different environments. Basically, they
will be affected by the environmental influences in two ways:
– by the effects of short-term extreme environmental conditions which may directly cause
malfunction or destroy the product;
– by the effect of long-term subjection to non-extreme environmental stresses which may
slowly degrade the product and finally cause malfunction or destruction of the product.
Short-term extreme environmental conditions may occur at any time in the product's life. A
product may be unaffected by an extreme condition when it is new but fail when it is subjected
to the same condition after being used for a long period of time due to the effect of ageing. The
order in which the environmental conditions are applied may affect the results of an evaluation.
It is important for the product specification, when referring to a certain class in IEC 60721-3 (all
parts), to define whether the product is required to be capable of operating or only to survive
without permanent damage when being exposed to the conditions described by the class.
The environmental classes may be used as a basis for the selection of design and test
severities with respect to the consequence of failure. Information contained in IEC 60721-3 (all
parts) may be used to help establish expected requirements for use, storage, transportation,
etc., and in the development of relevant specifications. The selected severities used for testing
should attempt to produce the effects of the actual environment.
EXAMPLE 1 A high temperature test on a heat dissipating product is designed to simulate the thermal effect of
subjecting a product to conditions of high air temperature, solar radiation and other possible heat sources
dependent on the application.
EXAMPLE 2 In a mechanical shock test, the product can be subjected to mechanical shocks of simple pulse
shapes (e.g., half-sine), while the actual conditions cannot be described by such simple pulses.
It is recognized that extreme or special environmental conditions may exist which require
consideration of severities that are not addressed in this document. The user of this document
should select the lowest classification necessary for covering the conditions of the intended
use.
5 Classification of groups of environmental parameters and their severities
5.1 General
Several classes for climatic conditions (K), special climatic conditions (Z), biological
conditions (B), mechanically active substances (S), and mechanical conditions (M) are
specified.
This classification allows for several possible combinations of environmental conditions which
bear upon products wherever in use. It represents the real situation in respect of world-wide
conditions of use, due to local influences of open-air climate, construction of buildings,
mounting, process conditions, etc.
For certain environmental parameters, it has not yet been possible to specify quantitative
severities.
For a given location or product, reference should be made to the total set of classes, for
example:
3K21/3Z1/3B1/3S6/3M11
5.2 Climatic conditions (K)
The classes defined in previous versions of this document have been replaced with new
classes as a result of recent efforts at collecting information regarding climatic conditions.
Those results are contained in technical reports referenced in this document.
When selecting appropriate classes, attention should be paid to the fact that the climatic
conditions inside buildings may depend on the outside (open-air) conditions, especially air
temperature and solar radiation, and the type of building construction. Walls with good thermal
insulation or high thermal capacity can consistently smooth the peaks of outside air
temperature variations between day and night, or, exceptionally, those produced over a longer
period of time. Walls with poor thermal insulation or low thermal capacity cannot have this
effect and peaks can be magnified due to the effect of solar radiation during the day, and to the
effect of building radiation at night. The effect of solar radiation can be increased by either
heat-trap or greenhouse effects.
The climatic conditions specified for classes 3K20 to 3K24 refer to the conditions in use of the
products. These conditions have been experienced world-wide over a long period of time taking
into account all the parameters that can influence them, such as open-air climatic conditions,
type of building construction, temperature/humidity controlling systems, and internal conditions,
for example heat dissipation from other equipment, presence of humans. The conditions should
cover all normal cases, but not exceptional events. These conditions are specified in Table 1.
The interdependence of temperature to relative humidity is shown in Annex A.
Enclosed locations
– 3K20 applies to fully air-conditioned enclosed locations. Air temperature and humidity
control is used continuously to maintain the required conditions.
– 3K21 applies to continuously temperature-controlled enclosed locations. Humidity is not
normally controlled.
Heating, cooling or humidification is used where necessary to maintain the required
conditions, especially where there is a large difference between them and the open-air
climate. Installed products may be exposed to secondary effects of solar radiation due to
increased ambient temperature and to heat radiation. They may also be exposed to
movements of surrounding air due to draughts in buildings, for example through open
windows, or due to special process conditions.
– 8 – IEC 60721-3-3:2019 © IEC 2019
The conditions of this class may be found in continuously manned offices, workshops, data
centres and other rooms for special applications.
– 3K22 applies to temperature-controlled enclosed locations. Humidity is not controlled.
Heating or cooling is used to maintain the required conditions, especially where there is a
large difference between them and the open-air climate.
The conditions of this class may be found in normal living or working areas, for example
living rooms, rooms for general use (theatres, restaurants, etc.), offices, shops, workshops
for electronic assemblies and other electrotechnical products, telecommunication centres,
storage rooms for valuable and sensitive products.
– 3K23 applies to enclosed locations having no temperature or humidity control.
Heating may be used to raise low temperatures, especially where there is a large difference
between the conditions of this class and the open-air climate.
Installed products may be subjected to formation of ice.
The conditions of this class may be found in some entrances and staircases of buildings, in
garages, cellars, certain workshops, buildings in factories and industrial process plants,
unattended equipment stations, certain telecommunication buildings, ordinary storage
rooms for frost-resistant products, farm buildings, etc.
– 3K24 applies to locations having neither temperature nor humidity control.
The location may have openings directly to the open air. The climatic conditions of this
class may be affected to a varying extent by the conditions of the open-air climate and the
construction of the building.
Installed products may be subjected to formation of ice.
The conditions of this class may be found in entrances to buildings, in garages, shacks,
unattended buildings, etc.
5.3 Special climatic conditions (Z)
Parameters such as heat radiation, and air pressure may occur with any severity in
combination with any of the other climatic conditions. These conditions are specified in Table 2.
5.4 Biological conditions (B)
No quantitative severity has been specified for these conditions. These conditions are specified
in Table 3. The specified parameters are typical but may not be complete.
– 3B1 applies to locations with environmental controls in place to prevent the growth of mould
and physical controls are in place to prevent attacks by animals.
– 3B2 applies to locations without environmental or physical controls in place to prevent
mould growth or attacks by animals, except termites.
– 3B3 applies to locations where attacks by termites or similar fauna may occur.
5.5 Chemically active substances (C)
The contamination of the natural atmosphere is mainly caused by chemical emissions from
industrial activities, motor-driven vehicles, and heating systems. A further chemical influence is
caused by aerosols of sea and road salts. Contamination may affect the function and materials
of products. Additional details regarding the categorization of these conditions may be found in
ISO 9223.
5.6 Mechanically active substances (S)
Dust and sand are classified together, as the effects caused by these environmental conditions
are similar. These conditions are specified in Table 4.
– 3S5 applies to locations where precautions have been taken to minimize the presence of
dust and sand. Ingress of sand is prevented.
– 3S6 applies to locations not situated in proximity to dust or sand sources and with no
special precautions to minimize the ingress of dust or sand.
– 3S7 applies to enclosed locations in close proximity to sand or dust sources, including
urban areas and with no special precautions to minimize the ingress of dust or sand.
5.7 Mechanical conditions (M)
Mechanical conditions relate to the levels of vibration and shock that may exist at the location,
for example as a result of normal operations, nearby vehicular movement. These conditions
are specified in Table 5. See Annex B for the definition of seismic environment.
– 3M10 applies to locations experiencing insignificant levels of vibration and shock.
– 3M11 applies to locations experiencing low levels of vibration and insignificant levels of
shock, such as those transmitted from air conditioning, machines or passing vehicles in the
vicinity.
– 3M12 applies to locations experiencing significant levels of vibration and shock, such as
those close to heavy machines and conveyor belts.
Table 1 – Classification of climatic conditions
Environmental parameter Unit
3K20 3K21 3K22 3K23 3K24
d
Low air temperature °C +20 +15 +5
−5 −25
d
High air temperature °C +25 +32 +40 +55 +55
a
Low relative humidity % 20 10 5 10 5
a
High relative humidity % 75 75 85 100 100
a 3
Low absolute humidity g/m 4 2 1 0,5 0,5
a 3
High absolute humidity g/m 15 22 25 29 29
b
Rate of change of temperature °C/min 0,1 0,5 0,5 0,5 0,5
f
Low air pressure kPa 70 70 70 70 70
f
High air pressure kPa 106 106 106 106 106
g
Solar radiation W/m No 500 700 700 700
e e e e
Heat radiation Not No
specified
c
Movement of surrounding air m/s 0,5 1,0 1,0 1,0 5,0
h h
Condensation Not No No No Yes Yes
specified
Water from sources other than rain Not No No No Dripping Dripping
specified water water
Formation of ice and frost (including freeze- Not No No No Yes Yes
thaw) specified
a
The low and high relative humidity severities are limited by the low and high absolute humidity and high
and low temperature. The extreme severities of relative humidity, absolute humidity and temperature
cannot occur simultaneously. See Annex A.
b
Averaged over a period of time of 5 min.
c
A cooling system based on non-assisted convection may be disturbed by adverse movement of
surrounding air.
d
These are air-conditioned locations with a tolerance of ±2 °C on the stated temperature value.
e
Conditions occurring at the location concerned to be selected from Table 2.
f If applicable, a special value may be selected from Table 2.
g Secondary effects from the solar radiation behave as heating effect.
h Limited to no occurrence of condensation.
– 10 – IEC 60721-3-3:2019 © IEC 2019
Table 2 – Classification of special climatic conditions
Environmental parameter Class Unit Special condition Z
3Z12 84 (approx. 1 500 m above sea level)
Low air pressure
3Z13 kPa 62 (approx. 4 000 m above sea level)
a
High air pressure 3Z14 114
3Z1 Negligible
Heat radiation, for example in the
3Z2
vicinity of room heating systems
Heat radiation No
Heat radiation, for example in the
vicinity of room heating systems or
3Z3
commercial ovens or industrial
furnaces
a
Conditions in pressurised rooms, for example clean rooms, operation theatres.
Table 3 – Classification of biological conditions
Units Class
3B1 3B2 3B3
Presence of mould, fungus, etc.
No Negligible
Presence of rodents and other animals
harmful to products
excluding termites including termites
Table 4 − Classification of mechanically active substances
Class
Environmental parameter Unit
3S5 3S6 3S7
Setting (sedimentary) dust mg/(m ⋅d) No 6 Note
Turbulent (suspended) dust No No 600
mg/(m ⋅h)
Windblown dust mg/m
No No No
m/s
NOTE Encompassed within turbulent (suspended) dust.
Table 5 − Classification of mechanical conditions
Class
Environmental parameter Unit
3M10 3M11 3M12
Stationary vibration, random:
2 2
(m/s ) /Hz 0,01 0,1
acceleration spectral density No
Frequency range Hz 5 to 200 5 to 200
Shock m/s No No 20
Annex A
(informative)
Interdependence of air temperature,
relative air humidity, and absolute air humidity
Annex A contains a climatogram (see Figure A.1) showing the interdependence of air
temperature, relative air humidity and absolute air humidity. For a given severity of low or high
absolute air humidity, the relevant severity of relative air humidity at a given air temperature
within the temperature range of a class may be found at the point where the curve for constant
absolute air humidity cuts the straight line for air temperature and relative air humidity.
Figure A.1 – Climatogram of interdependence of air temperature,
relative air humidity, and absolute air humidity
– 12 – IEC 60721-3-3:2019 © IEC 2019
Annex B
(informative)
Definition of seismic environment
For the general description and definition of the seismic excitation relay see IEC 60721-2-6.
During an earthquake, electromechanical components and equipment are subjected to motions
that can overstress equipment frames, circuit boards, and connectors.
The seismic excitation which equipment experiences during an earthquake depends on several
parameters including the ground motion intensity, structural characteristics of a building,
elevation of the equipment in a building, and characteristics of the structures used to support
and house equipment.
The most common method for specifying seismic conditions taking into account all these
parameters is through the definition of a shock response spectrum (SRS); for the meaning of
SRS see IEC 60068-2-27. The SRS may be used to describe the motion that equipment is
expected to experience at its mounting during a postulated seismic event.
To define an SRS, it is necessary to define the base motion. The high frequency asymptotic
value of the acceleration of the response spectrum is normally called zero period acceleration
(ZPA) and represents the largest peak value of acceleration of the base motion.
In the absence of a detailed knowledge of the possible seismic motion, the ZPA value can be
obtained by the following formula (see IEC 60068-3-3):
ZPA= a= a×K××D G
fg
where:
a is the base acceleration;
f
a is the peak ground acceleration (PGA) that depends on the intensity of the earthquake;
g
K is the super-elevation factor that takes into account the amplification of the ground
acceleration resulting from the vibrational behaviour of buildings and structures;
D is the direction factor that takes into consideration possible intensity differences of the
seismic motion between the horizontal and vertical axes; and
G is the geometric factor, normally specified among testing parameters when single axis
excitation is used for testing to take into account the interaction, due to installation
location, along the different axes of the equipment of simultaneous multi-directional input
vibrations.
The peak ground acceleration, a , depends upon the seismicity of the zone where it is
g
expected that the equipment will be installed for in-service conditions.
Figure 5 in IEC 60721-2-6:1990 shows the map of seismic activity zones. Zone 4 corresponds
to the highest seismic activity areas, Zone 3 the next highest, and so on. Geographic areas
designated as Zone 0 represent no substantial seismic activity.
Table B.1 correlates the seismic zone with the expected magnitude given by different seismic
scales and the expected peak ground acceleration. The correspondence among the peak
ground acceleration, the seismic activity zone and the modified Mercalli index are taken from
IEC TS 62271-210.
Table B.1 – Correlation of seismic zones with expected magnitudes
Seismic activity Peak ground acceleration (PGA) Modified Mercalli index
Richter scale
zone (m/s ) (MMI)
0,01 I 0 to 2
0,01 to 0,02 II 1 to 2
0,02 to 0,05 III 2 to 3
0,05 to 0,1 IV 3 to 4
0,1 to 0,2 V 4 to 5
0,2 to 0,5 VI 5 to 6
2 0,05 to 1 VII 5 to 7
3 1 to 2 VIII 6 to 8
2 to 5 IX 7 to 9
5 to 10 X
10 to 20 XI 8 or higher
more than 20 XII
– 14 – IEC 60721-3-3:2019 © IEC 2019
Bibliography
IEC 60068-2-27, Environmental testing – Part 2: Tests – Test Ea and guidance: Shock
IEC 60068-3-3, Environmental testing – Part 3: Guidance – Seismic test methods for
equipments
IEC 60721-2 (all parts), Classification of environmental conditions – Part 2-X: Environmental
conditions appearing in nature
IEC 60721-2-1, Classification of environmental conditions − Part 2-1: Environmental conditions
appearing in nature − Temperature and humidity
IEC 60721-2-2, Classification of environmental conditions – Part 2-2: Environmental conditions
appearing in nature – Precipitation and wind
IEC 60721-2-3, Classification of environmental conditions – Part 2-3: Environmental conditions
appearing in nature – Air pressure
IEC 60721-2-4, Classification of environmental conditions – Part 2-4: Environmental conditions
appearing in nature – Solar radiation and temperature
IEC 60721-2-5, Classification of environmental conditions – Part 2-5: Environmental conditions
appearing in nature – Dust, sand, salt mist
IEC 60721-2-6:1990, Classification of environmental conditions – Part 2-6 Environmental
conditions appearing in nature – Earthquake vibration and shock
IEC 60721-3 (all parts), Classification of environmental conditions – Part 3-X: Classification of
groups of environmental parameters and their severities
IEC TR 62130, Climatic field data including validation
IEC TR 62131-5, Environmental conditions – Vibration and shock of electrotechnical equipment
– Part 5: Equipment during storage and handling
IEC TS 62271-210, High-voltage switchgear and controlgear – Part 210: Seismic qualification
for metal enclosed and solid-insulation enclosed switchgear and controlgear assemblies for
rated voltages above 1 kV and up to and including 52 kV
ISO 9223, Corrosion of metals and alloys — Corrosivity of atmospheres — Classification,
determination and estimation
___________
– 16 – IEC 60721-3-3:2019 © IEC 2019
SOMMAIRE
AVANT-PROPOS . 17
1 Domaine d'application . 19
2 Références normatives . 19
3 Termes et définitions . 19
4 Généralités . 20
5 Classification des groupements des agents d'environnement et de leurs sévérités . 21
5.1 Généralités . 21
5.2 Conditions climatiques (K) . 21
5.3 Conditions climatiques spéciales (Z) . 23
5.4 Conditions biologiques (B) . 23
5.5 Substances chimiquement actives (C) . 23
5.6 Substances mécaniquement actives (S) . 23
5.7 Conditions mécaniques (M) . 23
Annexe A (informative) Interdépendance de la température de l'air, de l’humidité
relative de l'air et de l’humidité absolue de l’air . 26
Annexe B (informative) Définition de l’environnement sismique . 27
Bibliographie . 29
Figure A.1 – Climatogramme de l'interdépendance de la température de l'air, de
l’humidité relative de l'air et de l’humidité absolue de l’air . 26
Tableau 1 – Classification des conditions climatiques . 24
Tableau 2 – Classification des conditions climatiques spéciales . 25
Tableau 3 – Classification des conditions biologiques . 25
Tableau 4 – Classification des substances mécaniquement actives . 25
Tableau 5 – Classification des conditions mécaniques . 25
Tableau B.1 – Corrélation des zones sismiques avec les magnitudes attendues . 28
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
CLASSIFICATION DES CONDITIONS D'ENVIRONNEMENT –
Partie 3-3: Classification des groupements des agents d'environnement et
de leurs sévérités – Utilisation à poste fixe, protégé contre les intempéries
AVANT-PROPOS
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