EN IEC 60068-3-3:2019
(Main)Environmental testing - Part 3-3: Supporting documentation and guidance - Seismic test methods for equipment
Environmental testing - Part 3-3: Supporting documentation and guidance - Seismic test methods for equipment
IEC 60068-3-3:2019 applies primarily to electro-technical equipment but its application can be extended to other equipment and to components. In addition, if some type of analysis is always performed when making a seismic qualification, for example for the choice of the representative sample to be tested or for the extension of the seismic qualification from the tested specimen to similar specimens, the verification of the performance of an equipment by analysis or by a combination of testing and analysis can be acceptable but is outside the scope of this document, which is restricted to verification based entirely upon data from dynamic testing. This second edition cancels and replaces the first edition published in 1991. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - the main aim of this revision is to connect the testing level to the seismic activity level of the zone where the equipment could be installed; - a standard shape for the required response spectrum is also given for the general seismic class for which the seismic environment is either not known or is imprecisely known; - Clauses 11 to 15 were renumbered and some adjustments were made as their content is very general and the requirements can be applied both to the general seismic class and to the specific seismic class; - the word “envelope” is replaced with “dominance” and “to envelop” with “to dominate” in order to provide a more precise meaning from a mathematical point of view.
Umgebungseinflüsse - Teil 3-3: Unterstützende Dokumentation und Leitfaden - Seismische Prüfverfahren für Geräte
Essais d’environnement - Partie 3-3: Documentation d’accompagnement et recommandations - Méthodes d’essais sismiques applicables aux matériels
L’IEC 60068-3-3:2019 s’applique principalement au matériel électrotechnique mais son application peut s’étendre à d’autres matériels et composants. Par ailleurs, si un certain type d’analyse est toujours effectuée lors de la réalisation d’une qualification sismique, par exemple pour choisir l’échantillon représentatif à soumettre à essai ou pour étendre la qualification sismique du spécimen soumis à essai à des spécimens similaires, la vérification des performances d’un matériel par l’analyse ou par une combinaison d’essais et d’analyses peut être acceptable mais elle n’entre pas dans le domaine d’application du présent document, qui se limite à la vérification uniquement fondée sur les données d’essais dynamiques. Cette deuxième édition annule et remplace la première édition parue en 1991. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - le principal objectif de la présente révision est d’adapter le niveau d’essai au niveau d’activité sismique de la zone où le matériel est susceptible d’être installé; - une forme normalisée du spectre de réponse spécifié est également fournie pour la classe sismique générale pour laquelle l’environnement sismique n’est pas connu ou l’est de manière imprécise; - les Articles 11 à 15 ont été renumérotés et plusieurs ajustements ont été effectués car le contenu de ces articles est très général et les exigences peuvent s’appliquer aussi bien à la classe sismique générale qu’à la classe sismique spécifique; - le terme «enveloppe» est remplacé par «dominance» et «envelopper» par «dominer» afin d’expliciter ces termes du point de vue mathématique.
Okoljsko preskušanje - 3-3. del: Podporna dokumentacija in navodilo - Seizmične preskusne metode za opremo (IEC 60068-3-3:2019)
Ta dokument se uporablja predvsem za elektrotehnično opremo, vendar ga je mogoče uporabljati tudi za drugo opremo in sestavne dele. Dodatno velja naslednje: če se pri pripravi seizmične kvalifikacije vedno izvaja neka analiza, na primer za izbiro reprezentativnega vzorca za preskus ali za razširitev seizmične kvalifikacije s preskušenega vzorca na podobne vzorce, je lahko sprejemljivo preverjanje delovanja opreme z analizo ali s kombinacijo preskušanja in analize, vendar je to zunaj področja uporabe tega dokumenta, ki je omejen na preverjanje na podlagi podatkov iz dinamičnega preskušanja. Ta dokument obravnava zgolj seizmično preskušanje opreme v polni velikosti, ki se lahko preskuša na vibracijski mizi. Seizmično preskušanje opreme je namenjeno izkazovanju njene zmožnosti za izvajanje potrebnih funkcij med in/ali po tem, ko je bila podvržena obremenitvam in premikom zaradi potresa. Namen tega dokumenta je predstaviti nabor metod za preskušanje, ki jih je, kadar tako določa ustrezna specifikacija, mogoče uporabiti za izkazovanje zmogljivosti opreme, za katero se zahteva seizmično preskušanje, katerega glavni cilj je doseganje kvalifikacije.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2019
Nadomešča:
SIST EN 60068-3-3:2001
Okoljsko preskušanje - 3-3. del: Podporna dokumentacija in navodilo - Seizmične
preskusne metode za opremo (IEC 60068-3-3:2019)
Environmental testing - Part 3-3: Supporting documentation and guidance - Seismic test
methods for equipment (IEC 60068-3-3:2019)
Umgebungseinflüsse - Teil 3-3: Leitfaden - Seismische Prüfverfahren für Geräte (IEC
60068-3-3:2019)
Essais d'environnement - Partie 3-3: Guide - Méthodes d'essais sismiques applicables
aux matériels (IEC 60068-3-3:2019)
Ta slovenski standard je istoveten z: EN IEC 60068-3-3:2019
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 60068-3-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2019
ICS 19.040 Supersedes EN 60068-3-3:1993 and all of its
amendments and corrigenda (if any)
English Version
Environmental testing - Part 3-3: Supporting documentation and
guidance - Seismic test methods for equipment
(IEC 60068-3-3:2019)
Essais d'environnement - Partie 3-3: Documentation Umgebungseinflüsse - Teil 3-3: Unterstützende
d'accompagnement et recommandations - Méthodes Dokumentation und Leitfaden - Seismische Prüfverfahren
d'essais sismiques applicables aux matériels für Geräte
(IEC 60068-3-3:2019) (IEC 60068-3-3:2019)
This European Standard was approved by CENELEC on 2019-09-27. 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, 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
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60068-3-3:2019 E
European foreword
The text of document 104/835/FDIS, future edition 2 of IEC 60068-3-3, 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 60068-3-3:2019.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-06-27
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-09-27
document have to be withdrawn
This document supersedes EN 60068-3-3:1993 and all of its amendments and corrigenda (if any).
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 60068-3-3:2019 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60721-2-6:1990 NOTE Harmonized as HD 478.2.6 S1:1993 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-1 - Environmental testing - Part 1: General EN 60068-1 -
and guidance
IEC 60068-2-6 - Environmental testing - Part 2-6: Tests - EN 60068-2-6 -
Test Fc: Vibration (sinusoidal)
IEC 60068-2-47 - Environmental testing - Part 2-47: Test - EN 60068-2-47 -
Mounting of specimens for vibration,
impact and similar dynamic tests
IEC 60068-2-57 - Environmental testing - Part 2-57: Tests - EN 60068-2-57 -
Test Ff: Vibration - Time-history and sine-
beat method
IEC 60068-2-64 - Environmental testing - Part 2-64: Tests - EN 60068-2-64 -
Test Fh: Vibration, broadband random and
guidance
IEC 60068-2-81 - Environmental testing - Part 2-81: Tests - EN 60068-2-81 -
Test Ei: Shock - Shock response spectrum
synthesis
ISO 2041 - Vibration and shock - Vocabulary - -
IEC 60068-3-3 ®
Edition 2.0 2019-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 3-3: Supporting documentation and guidance – Seismic test methods for
equipment
Essais d’environnement –
Partie 3-3: Documentation d’accompagnement et recommandations – Méthodes
d’essais sismiques applicables aux matériels
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-7097-4
– 2 – IEC 60068-3-3:2019 © IEC 2019
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 General and qualification considerations . 14
4.1 General seismic class and specific seismic class . 14
4.2 Service conditions . 14
4.3 Malfunction criteria . 15
4.4 Qualification criteria . 15
5 Testing procedures . 15
5.1 General . 15
5.2 Mounting . 15
5.3 Measurements . 15
5.3.1 Vibration measurements at the vibration table . 15
5.3.2 Vibration measurements on the equipment . 16
5.3.3 Functional monitoring of the equipment . 16
5.4 Frequency range . 16
6 Conditioning . 16
7 Test wave selection . 16
7.1 General . 16
7.2 Multifrequency waves. 16
7.3 Single-frequency waves . 17
8 Test waves . 17
8.1 General . 17
8.1.1 Specification of test waves . 17
8.1.2 Simulation with a safety margin of the effects of an earthquake . 17
8.2 Multifrequency wave testing . 18
8.2.1 General requirements . 18
8.2.2 Time-history test . 18
8.2.3 Other multifrequency tests . 18
8.3 Single-frequency testing . 19
8.3.1 General requirements . 19
8.3.2 Sine-sweep test . 19
8.3.3 Sine-beat test . 19
8.3.4 Continuous sine test . 20
8.4 Other test wave forms . 20
9 Testing conditions . 20
9.1 General . 20
9.2 Vibration response investigation . 21
9.3 Test methods . 21
9.3.1 Test method for equipment without critical frequencies . 21
9.3.2 Test method for equipment with critical frequencies . 22
9.4 Selection of damping . 22
9.5 S1-earthquake and S2-earthquake testing . 23
IEC 60068-3-3:2019 © IEC 2019 – 3 –
9.6 Specific application testing . 23
9.7 Assembly testing . 23
9.8 Component testing . 23
10 Single and multi-axis testing . 24
10.1 General . 24
10.2 Single-axis testing . 24
10.3 Biaxial testing . 24
10.3.1 General requirements . 24
10.3.2 Two horizontal axes . 24
10.3.3 One horizontal axis and one vertical axis . 24
10.4 Triaxial testing . 25
10.4.1 General . 25
10.4.2 Triaxial installation . 25
10.4.3 Biaxial installation (one horizontal axis, one vertical axis) . 26
11 Conditioning for the general seismic class . 26
11.1 Selection of test type . 26
11.2 Test method . 26
12 Calculated amplitude test method for the general seismic class . 27
12.1 Application . 27
12.2 Testing conditions . 27
12.2.1 General . 27
12.2.2 Performance level . 27
12.2.3 Test wave selection . 27
12.2.4 Damping ratio . 27
12.2.5 Ground acceleration (a ) . 27
g
12.2.6 Superelevation factor (K) . 29
12.2.7 Direction factor (D) . 29
12.2.8 Floor acceleration (a ) . 30
f
13 Testing parameters for the general seismic class . 30
13.1 Duration of test . 30
13.2 Test acceleration (a ) . 30
t
13.2.1 General . 30
13.2.2 Wave factor (α) . 31
13.2.3 Geometric factor (G) . 31
14 Required response spectrum for the general seismic class . 31
15 Testing procedures for the general seismic class . 32
15.1 Vibration response investigation (VRI) . 32
15.2 Types of test . 33
15.2.1 Sine-beat test . 33
15.2.2 Sine-sweep test . 33
15.2.3 Time-history test . 33
15.2.4 Other test wave forms . 33
16 Conditioning for the specific seismic class . 33
17 Test wave selection for the specific seismic class . 34
17.1 General . 34
17.2 Multifrequency waves. 34
17.3 Single-frequency waves . 34
18 Test waves for the specific seismic class . 34
– 4 – IEC 60068-3-3:2019 © IEC 2019
18.1 General . 34
18.2 Single-frequency testing . 34
18.2.1 General . 34
18.2.2 Sine-sweep test . 34
18.2.3 Sine-beat test . 34
18.2.4 Continuous sine test . 35
18.3 Other test wave forms . 35
19 Testing conditions for the specific seismic class . 35
20 Single and multi-axis testing for the specific seismic class . 35
Annex A (informative) Flow charts for test selection . 43
A.1 Selection of test type . 43
A.2 General seismic class – Calculated amplitude test . 44
A.3 Specific seismic class – Single axis testing . 45
A.4 Specific seismic class – Multi-axis testing . 46
Bibliography . 47
Figure 1 – Shape of a required response spectrum in generalized form (log-log scale)
(as recommended by IEC 60068-2-57) . 32
Figure 2 – Typical envelope response spectrum . 35
Figure 3 – Types of response spectrum envelopes . 36
Figure 4 – Multifrequency response spectrum with superimposed sine beats . 37
Figure 5 – Sequence of five sine beats with five cycles . 37
Figure 6 – Typical time history . 38
Figure 7 – Continuous sine . 39
Figure 8 – Biaxial table along an inclined plane . 40
Figure 9 – Wave amplification factors . 41
Figure 10 – Vibration amplitudes for ground acceleration a with crossover frequencies
g
at 0,8 Hz and 1,6 Hz . 42
Figure A.1 – Selection of seismic class . 43
Figure A.2 – Calculated amplitude test flowchart . 44
Figure A.3 – Single-axis testing flowchart . 45
Figure A.4 – Multi-axis testing flowchart . 46
Table 1 – Typical damping ratios (per cent of critical) . 22
Table 2 – Selection of test type . 26
Table 3 – Ground acceleration levels . 27
Table 4 – Correspondence between peak ground acceleration and some seismic
scales . 28
Table 5 – Recommended superelevation factors (K) . 29
Table 6 – Direction factors (D) . 29
Table 7 – Wave factor . 31
IEC 60068-3-3:2019 © IEC 2019 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 3-3: Supporting documentation and guidance –
Seismic test methods for equipment
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 60068-3-3 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 1991. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the main aim of this revision is to connect the testing level to the seismic activity level of
the zone where the equipment could be installed;
b) a standard shape for the required response spectrum is also given for the general seismic
class for which the seismic environment is either not known or is imprecisely known;
– 6 – IEC 60068-3-3:2019 © IEC 2019
c) Clauses 11 to 15 were renumbered and some adjustments were made as their content is
very general and the requirements can be applied both to the general seismic class and to
the specific seismic class;
d) the word “envelope” is replaced with “dominance” and “to envelop” with “to dominate” in
order to provide a more precise meaning from a mathematical point of view.
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/835/FDIS 104/841/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.
This International Standard is to be used in conjunction with IEC 60068-1.
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.
IEC 60068-3-3:2019 © IEC 2019 – 7 –
INTRODUCTION
Guidance is included in each of the two test methods referred to in this document but it is
specific to the test method. The guidance in this document is directed towards choosing the
appropriate test method and applying it to seismic testing.
– 8 – IEC 60068-3-3:2019 © IEC 2019
ENVIRONMENTAL TESTING –
Part 3-3: Supporting documentation and guidance –
Seismic test methods for equipment
1 Scope
This part of IEC 60068 applies primarily to electro-technical equipment but its application can
be extended to other equipment and to components.
In addition, if some type of analysis is always performed when making a seismic qualification,
for example for the choice of the representative sample to be tested or for the extension of
the seismic qualification from the tested specimen to similar specimens, the verification of the
performance of an equipment by analysis or by a combination of testing and analysis can be
acceptable but is outside the scope of this document, which is restricted to verification based
entirely upon data from dynamic testing.
This document deals solely with the seismic testing of a full-size equipment which can be
tested on a vibration table. The seismic testing of an equipment is intended to demonstrate its
ability to perform its required function during and/or after the time it is subjected to the
stresses and displacements resulting from an earthquake.
The object of this document is to present a range of methods of testing which, when specified
by the relevant specification, can be applied to demonstrate the performance of equipment for
which seismic testing is required with the main aim of achieving qualification.
NOTE Qualification by so-called “fragility-testing” is not considered to be within the scope of this document which
has been prepared to give generally applicable guidance on seismic testing and specifically on the use of
IEC 60068-2 test methods.
The choice of the method of testing can be made according to the criteria described in this
document. The methods themselves are closely based on published IEC test methods.
This document is intended for use by manufacturers to substantiate, or by users to evaluate
and verify, the performance of an equipment.
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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-47, Environmental testing – Part 2-47: Test – Mounting of specimens for
vibration, impact and similar dynamic tests
IEC 60068-2-57, Environmental testing – Part 2-57: Tests – Test Ff: Vibration – Time-history
and sine-beat method
IEC 60068-3-3:2019 © IEC 2019 – 9 –
IEC 60068-2-64, Environmental testing – Part 2-64: Tests – Test Fh: Vibration, broadband
random and guidance
IEC 60068-2-81, Environmental testing – Part 2-81: Tests – Test Ei: Shock – Shock response
spectrum synthesis
ISO 2041, Mechanical vibration, shock and condition monitoring – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60068-1,
IEC 60068-2-6, IEC 60068-2-57 and ISO 2041 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
3.1
assembly
two or more devices sharing a common mounting or supporting structure
3.2
bandpass at –3 dB
frequency intervals defined by the points possessing an ordinate larger than or equal to 2 /2
times the maximum value of the plot
SEE: Figure 2.
3.3
basic response spectrum
unmodified response spectrum defined by the characteristics of the building, its floor level,
damping ratio, etc. and obtained from a specific ground motion
SEE: Figure 2.
Note 1 to entry: The basic response spectrum is generally of the narrow band type at floor level. The basic
response spectrum is calculated by the architect engineer of the plant and it is generally not known by the
equipment manufacturer and by the test engineer.
3.4
broadband response spectrum
response spectrum that describes the motion indicating that a number of interacting
frequencies exist which should be treated as a whole
SEE: Figure 3c).
Note 1 to entry: The bandwidth is normally greater than one octave.
3.5
critical frequency
frequency at which:
– malfunctioning and/or deterioration of performance of the specimen which are dependent
on vibration are exhibited, and/or
– mechanical resonances and/or other response effects occur, for example chatter
[SOURCE: IEC 60068-2-6:2007, 3.9]
– 10 – IEC 60068-3-3:2019 © IEC 2019
3.6
crossover frequency
frequency at which the characteristic of a vibration changes from one relationship to another
Note 1 to entry: For example, a crossover frequency may be that frequency at which the control of the test
vibration amplitude changes from a constant displacement value versus frequency to a constant acceleration value
versus frequency.
[SOURCE: ISO 2041:2009, 2.118, modified – Example omitted and note added.]
3.7
cut-off frequency
frequency in the response spectrum where the zero period acceleration (ZPA) asymptote
begins
Note 1 to entry: The cut-off frequency is the frequency beyond which the single-degree-of-freedom (SDOF)
oscillators exhibit no amplification of motion and indicate the upper limit of the frequency content of the waveform
being analysed.
3.8
damping
energy dissipation mechanisms in a system.
Note 1 to entry: In practice, damping depends on many parameters, such as the structural system, mode of
vibration, strain, applied forces, velocity, materials, joint slippage.
Note 2 to entry: This definition is not identical to that given in ISO 2041.
3.8.1
critical damping
minimum viscous damping that will allow a displaced system to return to its initial position
without oscillation
3.8.2
damping ratio
ratio of actual damping to critical damping in a system with viscous damping
3.9
direction factor
factor taking account of the difference in magnitude at ground level that normally exists
between the horizontal and vertical accelerations resulting from an earthquake
3.10
floor acceleration
acceleration of a particular building floor (or an equipment mounting) resulting from the
ground motion of a given earthquake
Note 1 to entry: In practice the floor acceleration may be resolved into its horizontal and vertical components.
3.11
geometric factor
factor required in single axis testing to take into account the interaction along the different
axes of the equipment of simultaneous multi-directional input vibrations
3.12
g
n
standard acceleration due to the earth's gravity, which itself varies with altitude and
geographical latitude
Note 1 to entry: For the purposes of this document, the value of g is rounded up to the nearest whole number,
n
that is 10 m/s .
IEC 60068-3-3:2019 © IEC 2019 – 11 –
3.13
ground acceleration
acceleration resulting from the motion of a given earthquake
Note 1 to entry: In practice the ground acceleration may be resolved into its horizontal and vertical components.
3.14
lateral frequencies
two frequencies determined according to the –3 dB response around the overall resonance
frequency
SEE: Figure 2.
3.15
malfunction
loss of capability of the equipment to initiate or sustain a required function, or the initiation of
undesired spurious action which may result in adverse consequences for safety
Note 1 to entry: Malfunction will be defined by the relevant specification.
3.16
narrowband response spectrum
response spectrum in which single-frequency excitation predominates
SEE: Figure 3a).
Note 1 to entry: The bandwidth is normally 1/3 oct (one third octave) or less.
Note 2 to entry: When several widely spaced well-defined frequencies exist, if justified, each of their responses
may be treated separately as a narrow-band response spectrum (see Figure 3b)).
3.17
damped natural frequency
frequency of free vibration of a damped linear system depending only on its own physical
characteristics (mass, stiffness, and damping)
3.18
overall resonance
resonance frequency at which a complete structure amplifies the exciting motion
Note 1 to entry: Within the frequency range between 1 Hz and 35 Hz, overall resonance generally corresponds to
the first mode of vibration. It is important to take into account the overall resonance frequencies when they are
enclosed in the strong part of the required response spectrum (see 3.27).
3.19
pause
interval between consecutive test waves (for example sine beats)
Note 1 to entry: A pause should be such that it results in no significant superposition of the response motions of
an equipment.
3.20
preferred testing axes
three orthogonal axes which correspond to the most vulnerable axes of the equipment
3.21
required response spectrum
RRS
response spectrum specified by the user
SEE: Figures 1, 2 and 3.
– 12 – IEC 60068-3-3:2019 © IEC 2019
3.22
resonance frequency
frequency at which, in forced oscillation, a change in the frequency of excitation causes a
decrease in the response of the system
Note 1 to entry: The value of resonance frequency depends upon the measured variable. For a damped linear
system, the values of resonance frequency for displacement, velocity and acceleration (respectively dynamic
compliance, mobility and accelerance; see ISO 2041) are in increasing order of frequency. The differences
between these resonance frequency values are small for the usual damping ratios.
Note 2 to entry: In seismic testing, it is often assumed that a resonance frequency is significant when the
transmissibility of the response is greater than 2.
Note 3 to entry: For a damped linear system the resonance frequency is coincident with the damped natural
frequency.
Note 4 to entry: This definition is not identical to that given in ISO 2041.
3.23
response spectrum
plot of the maximum response to a defined input motion of a family of single-degree-of-
freedom bodies at a specified damping ratio
SEE: Figures 1, 2 and 3.
Note 1 to entry: This definition is not identical to that given in ISO 2041.
3.24
S1-earthquake
earthquake which would be expected to occur during the operating life of the equipment and
for which safety related equipment is to be designed to continue to operate without
malfunction
Note 1 to entry: An S1-earthquake corresponds in nuclear applications to the operating base earthquake (OBE).
3.25
S2-earthquake
earthquake which produces the maximum vibratory ground motion for which certain
structures, systems and components are designed to remain functional
Note 1 to entry: The structures, systems and components are those essential to ensure proper function, integrity
and safety of the total system.
Note 2 to entry: An S2-earthquake corresponds in nuclear applications to the safe shutdown earthquake (SSE).
3.26
sine beat
continuous sinusoidal wave of one frequency which is modulated by a sinusoidal wave of a
lower frequency
SEE: Figure 5.
Note 1 to entry: The duration of one sine beat is half the period of the modulating frequency.
Note 2 to entry: In this document, the sine beat is considered as a single-frequency wave.
3.27
strong part of time history
part of time history from the time when the plot first reaches 25 % of the maximum value to
the time when it falls for the last time to the 25 % level
SEE: Figure 6.
IEC 60068-3-3:2019 © IEC 2019 – 13 –
3.28
strong part of the response spectrum
part of the spectrum for which the response acceleration is higher than for the –3 dB
bandpass of the required response spectrum
SEE: Figure 2.
Note 1 to entry: Generally, the strong part of the response spectrum is located in the first third of the frequency
band.
3.29
superelevation factor
factor accounting for the change in the acceleration with respect to the earth due to the
transmissibility of buildings and structures
3.30
synthesized time history
artificially generated time history such that its response spectrum dominates the required
response spectrum
3.31
test level
largest peak value within a test wave
Note 1 to entry: In seismic testing, acceleration is the parameter normally used.
3.32
test frequency
frequency at which the specimen is to be excited during a test
Note 1 to entry: A test frequency is one of two types as defined in 3.32.1 and 3.32.2.
3.32.1
predetermined test frequency
frequency specified by the relevant specification
3.32.2
investigated test frequency
frequency obtained by a vibration response investigation
3.33
test response spectrum
response spectrum derived from the real motion of the vibration table either analytically or by
using spectrum analysis equipment
SEE: Figures 2, 3c) and 3d).
3.34
time history
recording, as a function of time, of acceleration or velocity or displacement
Note 1 to entry: This definition is not identical to that given in ISO 2041.
3.35
zero period acceleration
ZPA
high-frequency asymptotic value of acceleration of a response spectrum
Note 1 to entry: An example of ZPA is given in Figure 2.
– 14 – IEC 60068-3-3:2019 © IEC 2019
Note 2 to entry: The zero period acceleration is of practical significance as it represents the largest peak value of
acceleration, for example in a time history. This should not be confused with the peak value of acceleration in the
response spectrum.
Note 3 to entry: This note applies to the French language only.
4 General and qualification considerations
4.1 General seismic class and specific seismic class
Two seismic classes have been established: a general seismic class and a specific seismic
class. Neither of these classes can be considered to be more demanding than the other. The
difference between the two classes lies in the availability of and/or the accuracy in defining
the characteristics of the seismic environment. When high reliability safety equipment for a
specified environment is required, such as safety related equipment in nuclear power plants,
the use of precise data is necessary and, therefore, the specific seismic class is applicable
and not the general seismic class. Annex A contains a flow chart for the selection of the test
class (general seismic class or specific seismic class) and three flow charts (Figures A.2 to
A.4) covering the possibilities discussed in this document. To tak
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...