kSIST FprEN IEC 61373:2025

SLOVENSKI STANDARD
oSIST prEN IEC 61373:2024
01-februar-2024
Železniške naprave - Oprema voznih sredstev - Preskusi na udarce in vibracije
Railway applications - Rolling stock equipment - Shock and vibration tests
Bahnanwendungen – Betriebsmittel von Bahnfahrzeugen – Prüfungen für Schwingen
und Schocken
Applications ferroviaires - Matériel roulant - Essais de chocs et vibrations
Ta slovenski standard je istoveten z: prEN IEC 61373:2023
ICS:
17.160 Vibracije, meritve udarcev in Vibrations, shock and
vibracij vibration measurements
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
oSIST prEN IEC 61373:2024 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 61373:2024
oSIST prEN IEC 61373:2024
9/3019/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61373 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2023-12-01 2024-02-23
SUPERSEDES DOCUMENTS:
9/2862/CD, 9/2896A/CC
IEC TC 9 : ELECTRICAL EQUIPMENT AND SYSTEMS FOR RAILWAYS
SECRETARIAT: SECRETARY:
France Mr Denis MIGLIANICO
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

Other TC/SCs are requested to indicate their interest, if any, in this
CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of CENELEC,
is drawn to the fact that this Committee Draft for Vote (CDV) is
submitted for parallel voting.
The CENELEC members are invited to vote through the CENELEC
online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are aware
and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clauses to be
included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC clauses. (See
AC/22/2007 or NEW GUIDANCE DOC).

TITLE:
Railway applications – Rolling stock equipment – Shock and vibration tests

PROPOSED STABILITY DATE: 2027
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

oSIST prEN IEC 61373:2024
9/3019/CDV – 2 – IEC CDV 61373  IEC 2023
CONTENTS
CONTENTS . 2
FOREWORD . 5
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 11
3 Terms, definitions, symbols and abbreviated terms . 11
3.1 Terms and definitions . 11
3.1.1 random vibration . 11
3.1.2 Gaussian distribution . 11
3.1.3 acceleration spectral density (ASD) . 12
3.1.4 component. 12
3.1.5 cubicle . 12
3.1.6 acceleration ratio . 12
3.1.7 weakest point . 12
3.2 Symbols and abbreviated terms. 12
4 General . 13
5 Order of testing . 13
6 Reference information required by the test house . 14
6.1 General . 14
6.2 Method of mounting and orientation of equipment under test . 14
6.3 Reference and check points . 16
6.3.1 General . 16
6.3.2 Fixing point . 17
6.3.3 Check point . 17
6.3.4 Reference point . 17
6.3.5 Measuring point . 17
6.4 Mechanical state and functioning during test . 18
6.4.1 Mechanical state . 18
6.4.2 Functional tests . 18
6.4.3 Performance tests . 18
6.5 Reproducibility for random vibration tests . 18
6.5.1 General . 18
6.5.2 Acceleration spectral density (ASD) . 18
6.5.3 Root mean square value (RMS) . 18
6.5.4 Probability density function (PDF) . 19
6.5.5 Duration . 19
6.6 Measuring tolerances . 19
6.7 Recovery . 19
7 Initial measurements and preconditioning . 19
8 Functional random vibration test conditions . 20
8.1 Test severity and frequency range . 20
8.1.1 Body mounted – Category 1 Class A . 21
8.1.2 Body mounted – Category 1 Class B . 24
8.1.3 Bogie mounted – Category 2 . 27
8.1.4 Axle mounted – Category 3 . 30
8.2 Duration of functional vibration tests . 32

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8.3 Functioning during test . 32
9 Simulated long-life testing at increased random vibration levels . 32
9.1 Test severity and frequency range . 32
9.1.1 Body mounted – Category 1 Class A . 33
9.1.2 Body mounted – Category 1 Class B . 34
9.1.3 Bogie mounted – Category 2 . 35
9.1.4 Axle mounted – Category 3 . 36
9.2 Duration and acceleration ratio of long-life vibration tests . 36
10 Shock testing conditions . 38
10.1 Pulse shape and tolerance . 38
10.2 Velocity changes . 38
10.3 Mounting . 38
10.4 Repetition rate . 38
10.5 Test severity, pulse shape and direction . 38
10.6 Number of shocks . 39
10.7 Functioning during test . 40
11 Transportation and handling . 40
12 Final measurements and acceptance criteria . 40
12.2 Acceptance criteria . 40
13 Test exemption . 41
14 Report . 41
15 Test certificate . 41
16 Disposal . 42
Annex A (informative) Explanation of service measurements, measuring positions,
methods of recording service data, summary of service data, and method used to
obtain random test levels from acquired service data . 44
Annex B (informative) Figure identifying general location of equipment on railway
vehicles and their resulting test category . 56
Annex C (informative) Example of a type test certificate . 57
Annex D (informative) Guidance for calculating RMS values from ASD values or levels . 58
Annex E (informative) Guidance for numerical validation of structural parts of cubicles . 60

Figure A.1 – Standard measuring positions used for axle, bogie (frame) and body . 44
Figure A.2 – Typical fatigue strength curve . 49
Figure A.3 – Acceleration ratio as function as number of cycles during long life test NT . 51
Figure A.4 – Default acceleration ratio as function as long-life test duration d for
LLT
categories 1 and 2 . 52
Figure A.4 – Default acceleration ratio as function as long-life test duration d for
LLT
category 3 . 52
Figure B.1 – General location of equipment on vehicles . 56
Figure D.1 – ASD spectrum . 59
Figure E.1 – Stress value on element, Frequency Response Analysis . 65
Figure E.2 – Power Spectral Density, acceleration and stress σPSD(f) . 65

Table 1 – Test severity and frequency range for functional random vibration tests of
Category 1 Class A . 23

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Table 2 – Test severity and frequency range for functional random vibration tests of
Category 1 Class B . 26
Table 3 – Test severity and frequency range for functional random vibration tests of
Category 2 . 28
Table 4 – Test severity and frequency range for functional random vibration tests of
Category 3 . 31
Table 5 – Test severity and frequency range for 5 hours simulated long-life random
vibration tests of Category 1 Class A . 33
Table 6 – Test severity and frequency range for 100 hours simulated long-life random
vibration tests of Category 1 Class A . 33
Table 7 – Test severity and frequency range for 5 hours simulated long-life random
vibration tests of Category 1 Class B . 34
Table 8 – Test severity and frequency range for 100 hours simulated long-life random
vibration tests of Category 1 Class B . 34
Table 9 – Test severity and frequency range for 5 hours simulated long-life random
vibration tests of Category 2 . 35
Table 10 – Test severity and frequency range for 100 hours simulated long-life random
vibration tests of Category 2 . 35
Table 11 – Test severity and frequency range for 5 hours simulated long-life random
vibration tests of Category 3 . 36
Table 12 – Test severity and frequency range for 100 hours simulated long-life random
vibration tests of Category 3 . 36
Table 13 – Acceleration ratio and long-life test duration table (default values) . 37
Table 4 – Test severity, pulse shape and direction . 39
Table A.1 – Environment data acquisition summary of the test parameters/conditions . 45
Table A.2 – Summary of the additional RMS acceleration levels obtained from the
questionnaire . 47
Table A.3 – Fatigue curves parameters considered for default acceleration ratio
computation . 50
Table A.4 – Acceleration ratio and long-life test duration table (default values) . 53
Table A.5 – Parameters for specific acceleration ratio computation (Example 1) . 54
Table A.6 – Parameters for specific acceleration ratio computation (Example 2) . 55

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________
RAILWAY APPLICATIONS –
ROLLING STOCK EQUIPMENT –
SHOCK AND VIBRATION TESTS
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 61373 has been prepared by IEC technical committee 9: Electrical
equipment and systems for railways.
This third edition cancels and replaces the second edition, issued in 2010 and constitutes a
technical revision.
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The main technical changes with regard to the previous edition are as follows:
– consideration of specific ASD spectra from onboard measurements and certification
limited to the specific case;
– exclusion from the scope of applicability of traction motors and any substructure not
equipped with electrical/electronic/pneumatic device;
– clarification for order of testing and typical test sequence, taking into account the
possibility of simultaneous multi-axis testing;
– recommendation and guidance for removing resilient mounts of the equipment (if located
between the equipment and the main structure) during the long-life test;
– qualification of the fixture device used to attach the equipment to the test bench;
– guidance for using a measuring point as a possibility to assess mechanical integrity;
– change of the method to calculate the acceleration ratio which has to be applied to the
functional ASD value to obtain the simulated long-life ASD value;
– duration of long-life test can be set from 5 hours to 100 hours per axis, with
corresponding acceleration ratio (default value) indicated in a table;
– clarification of the concept of structural integrity;
– description of test exemption cases, subassembly tests, and finite element analysis for
structural parts of equipment (new Annex E);
– the lowest frequency f1 of ASD spectra is fixed at 5 Hz whatever the mass of the
equipment for Categories 1 and 2;
– update of ASD spectra for functional random vibration test: Table 1, Table 2, Table 3,
Table 4, Table A.2 and Figure 5, Figure 6, Figure 7, Figure 9;

oSIST prEN IEC 61373:2024
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The text of this document is based on the following documents:
FDIS Report on voting
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
oSIST prEN IEC 61373:2024
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1 INTRODUCTION
2 This document covers the requirements for random vibration and shock testing items of
3 pneumatic, electrical and electronic equipment/components (hereinafter only referred to as
4 equipment) to be fitted on to railway vehicles. Random vibration and shock (as test method or
5 as numerical simulation) is the only method to be used for equipment/component approval.
6 The tests contained within this document are specifically aimed at demonstrating the ability of
7 the equipment under test to withstand the type of environmental vibration conditions normally
8 expected for railway vehicles. In order to achieve the best representation possible, the values
9 quoted in this document have been derived from actual service measurements submitted by
10 various bodies from around the world.
11 This document is not intended to cover self-induced vibrations as these will be specific to
12 particular applications.
13 Engineering judgement and experience are required in the execution and interpretation of this
14 document.
15 This document is suitable for design and validation purposes; however, it does not exclude the
16 use of other development tools (such as sine sweep), which may be used to ensure a
17 predetermined degree of mechanical and operational confidence. The test levels to be applied
18 to the equipment under test are dictated only by its location on the train (i.e. axle, bogie or
19 body-mounted).
20 It should be noted that these tests may be performed on prototypes in order to gain design
21 information about the product performance under random vibration. However, for test
22 certification purposes the tests have to be carried out on equipment taken from normal
23 production.
24 The procedures and requirements defined in this document do not substitute or overrule any
25 structural assessment required from other structural requirement standards. This document is
26 not intended to be used as a proof of fatigue strength.
27 NOTE European Standards EN 12663 and EN 13749 are examples of such structural requirement standards.
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29 RAILWAY APPLICATIONS –
30 ROLLING STOCK EQUIPMENT –
31 SHOCK AND VIBRATION TESTS
33 1 Scope
34 This International Standard specifies the requirements for testing items of equipment intended
35 for use on railway vehicles which are subsequently subjected to vibrations and shock owing to
36 the nature of railway operational environment. To gain assurance that the quality of the
37 equipment is acceptable, it has to withstand tests of reasonable duration that simulate the
38 service conditions seen throughout its expected life.
39 Simulated long-life testing can be achieved in a number of ways each having their associated
40 advantages and disadvantages, the following being the most common:
41 a) amplification: where the amplitudes are increased and the time base decreased;
42 b) time compression: where the amplitude history is retained and the time base is decreased
43 (increase of the frequency);
44 c) decimation: where time slices of the historical data are removed when the amplitudes are
45 below a specified threshold value.
46 The amplification method as stated in a) above, is used in this document and together with the
47 publications referred to in Clause 2; it defines the default test procedure to be followed when
48 vibration testing items for use on railway vehicles. However, other standards exist and may be
49 used with prior agreement between the manufacturer and the customer. In such cases test
50 certification against this document will not apply. Where service information is available, tests
51 can be performed using the method outlined in Annex A. If the levels are lower than those
52 quoted in this document, equipment is partially certified against this document (only for service
53 conditions giving functional test values lower than or equal to those specified in the test report).
54 Whilst this document is primarily concerned with railway vehicles on fixed rail systems, its wider
55 use is not precluded. For systems operating on pneumatic tyres, or other transportation systems
56 such as trolleybuses, where the level of shock and vibration clearly differ from those obtained
57 on fixed rail systems, the supplier and customer can agree on the test levels at the tender stage.
58 It is recommended that the frequency spectra and the shock duration/amplitude be determined
59 using the guidelines in Annex A.
60 Equipment tested at levels lower than those quoted in this document shall be resulting from an
61 agreement between supplier and customer, based on customized spectra resulting from
62 onboard measurements. Certification according to this document is reached but limited to the
63 specific case.
64 An example of this is trolleybuses, whereby body-mounted trolleybus equipment could be tested
65 in accordance with category 1 equipment referred to in the standard.
66 This document applies to single axis testing. However, multi-axis testing may be used with prior
67 agreement between the manufacturer and the customer.
68 The test values quoted in this document have been divided into three categories dependent
69 only upon the equipment’s location within the vehicle.
70 Category 1 Body mounted
71 Class A Cubicles, subassemblies, equipment and components mounted directly on or
72 under the car body.
73 Class B Anything mounted inside an equipment case which is in turn mounted directly on
74 or under the car body.
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75 Class B should be used when it is not clear where the equipment is to be located.
76 Category 2 Bogie mounted
77 Cubicles, subassemblies, equipment and components which are to be mounted on the bogie of
78 a railway vehicle.
79 Category 3 Axle mounted
80 Subassemblies, equipment and components or assemblies which are to be mounted on the
81 wheelset assembly of a railway vehicle.
82 In the case of equipment mounted on vehicles with one level of suspension such as wagons
83 and trucks, unless otherwise agreed at the tender stage, axle mounted equipment are tested
84 as category 3, and all other equipment are tested as category 2.
85 The cost of testing is influenced by the weight, shape and complexity of the equipment under
86 test. Consequently, the supplier may at the tender stage propose a more cost-effective method
87 of demonstrating compliance with the requirements of this document. Where alternative
88 methods are agreed, it will be the responsibility of the supplier to demonstrate to the customer
89 or its representative that the objective of this document has been met. If an alternative method
90 of evaluation is agreed, then the equipment tested cannot be certified against the requirements
91 of this document.
92 This document is intended to evaluate equipment which is attached to the main structure of the
93 vehicle (and/or components mounted thereon). It is not intended to test equipment which forms
94 part of the main structure. Main structure in the sense of this document means car body, bogie
95 and axle.
96 The following items are out of scope of this document:
97 - Traction motors for railway vehicles;
98 - Any mechanical substructure not equipped with electrical/electronic/pneumatic component.
99 There are a number of cases where additional or special vibration tests may be requested by
100 the customer, cases where additional or special vibration tests may be requested by the
101 customer, which are not specified in this document, for example:
102 a) equipment mounted on, or linked to, items which are known to produce defined frequency
103 excitation;
104 b) equipment such as traction motors, pantographs, shoegear, or suspension components
105 which may be subjected to tests in accordance with their special requirements, applicable
106 to their use on railway vehicles. In all such cases the tests carried out should be dealt with
107 by separate agreement at the tender stage;
108 c) equipment intended for use in special operational environments as specified by the
109 customer;
110 d) transportation and handling tests.
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112 2 Normative references
113 The following documents are referred to in the text in such a way that some or all of their content
114 constitutes requirements of this document. For dated references, only the edition cited applies.
115 For undated references, the latest edition of the referenced document (including any
116 amendments) applies.
117 IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
118 IEC 60068-2-47:2005, Environmental testing – Part 2-47: Tests – Mounting of specimens for
119 vibration, impact and similar dynamic tests
120 IEC 60068-2-64:2008, Environmental testing – Part 2-64: Tests – Test Fh: Vibration, broadband
121 random and guidance
122 ISO 3534-1:2006, Statistics – Vocabulary and symbols – Part 1: Probability and general
123 statistical terms
124 3 Terms, definitions, symbols and abbreviated terms
125 3.1 Terms and definitions
126 For the purposes of this document, the terms and definitions given in EC 60068-2-64, ISO 3534-
127 1 and the following apply. ISO and IEC maintain terminology databases for use in
128 standardization at the following addresses:
129 • ISO Online browsing platform: available at https://www.iso.org/obp
130 • IEC Electropedia: available at http://www.electropedia.org/
131 3.1.1 random vibration
132 vibration the instantaneous value of which cannot be precisely predicted for any given instant
133 of time
134 3.1.2 Gaussian distribution
135 Gaussian, or normal, distribution has a probability density function equal to (see Figure 1):
–(x – x)²
P (x) = . 2 . σ²
136 x
e
σ 2 . π
137 where:
138 σ is the RMS value;
139 is the instantaneous value;
x
140 x is the mean value of x .

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P (x)
x
+3σ
+2σ
x +1σ
x
x
t
–1σ
–2σ
–3σ
IEC  2338/11
142 Figure 1 – Gaussian distribution
143 NOTE According to Figure 1, the probability that the instantaneous acceleration value is between ±a is equal to the
144 zone under the probability density curve P (x). This means that the instantaneous acceleration value between:
x
145 • 0 and 1σ represents 68,26 % of the time,
146 • 1σ and 2σ represents 27,18 % of the time,
147 • 2σ and 3σ represents 4,30 % of the time.
148 3.1.3 acceleration spectral density (ASD)
149 mean-square value of that part of an acceleration signal passed by a narrow-band filter of a
150 centre frequency, per unit bandwidth, in the limit as the bandwidth approaches zero and the
151 averaging time approaches infinity
152 3.1.4 component
153 pneumatic, electrical, or electronic part located inside a cubicle.
154 3.1.5 cubicle
155 self-contained item of equipment, comprising structure, mechanical parts and mounted
156 components.
158 Note 1 to entry examples include converter, inverter, battery box.
159 3.1.6 acceleration ratio
160 coefficient applied to the functional ASD value to obtain the simulated long-life ASD value.
161 3.1.7 weakest point
162 structural area which provides the lowest margin of safety under fatigue loads.
163 3.2 Symbols and abbreviated terms
164 PCM Pulse Code Modulation
165 DAT Digital Audio Tape
166 FM Frequency Modulation
167 DR Digital Recorder
168 ADC Analog to Digital Converter
169 FEA Finite Element Analysis
170 PDF Probability Density Function

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171 RH Relative Humidity
172 4 General
173 This document is intended to highlight any weakness/error which may result in problems as a
174 consequence of operation under environments where vibration and shock are known to occur
175 in service on a railway vehicle. This is not intended to represent a full life test. However, the
176 test conditions are sufficient to provide some reasonable degree of confidence (depending on
177 hypothesis of fatigue strength parameters) that the equipment will survive the specified lifetime
178 under service conditions.
179 Compliance with this document is achieved if the criteria in Clause 13 are met.
180 The test levels quoted in this document have been derived from environmental test data, as
181 referred to in Annex A. This information was submitted by organizations responsible for
182 collecting environmental vibration levels under service conditions.
183 The following tests are mandatory for compliance with this document:
The functional random test levels are the minimum test
Functional random test
levels to be applied in order to demonstrate that the
equipment under test is capable of functioning when
subjected to conditions which are likely to occur in service,
on railway vehicles.
The degree of functioning shall be agreed between the
manufacturer and the end user prior to tests commencing
(see 6.3.2). Functional test requirements are detailed in
Clause 8.
The functional tests are not intended to be a full per-
formance evaluation under simulated service conditions.
Simulated long-life test This test is aimed at establishing the mechanical integrity
of the equipment at increased service levels. It is not
necessary to demonstrate ability to function under these
conditions. Simulated long-life testing requirements are
detailed in Clause 9.
Shock testing is aimed at simulating rare service events. It
Shock testing
is not necessary to demonstrate functionality during this
test. It will however be necessary to demonstrate that no
change in operational state occurs, that there is no visual
deformation and that mechanical integrity has not
changed. These points shall be clearly demonstrated in the
final test report. Shock testing requirements are detailed in
Clause 10.
185 5 Order of testing
186 Testing in the vertical, transverse and longitudinal axes may be performed in any order. A
187 possible sequence of testing is shown in Figure 2 for single axis test bench:

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189 Figure 2 – Test sequence
190 It is allowed to change the order of testing to reduce the effort for axis permutation.
191 It is allowed to permute shock test, functional random vibration test and simulated long-life
192 vibration test from the order suggested in the sequence above.
193 The order of testing shall be recorded in the report. Performance tests in accordance with 6.3.3
194 shall be undertaken in accordance with Figure 2.
195 For structural parts of the equipment (if applicable), transfer functions shall be taken for
196 comparison purposes in order to establish if any changes have taken place as a result of the
197 simulated long-life testing.
198 The orientation and direction of excitation shall be stated in the test specification and included
199 in the report.
200 6 Reference information required by the test house
201 6.1 General
202 Additional general information can be found in IEC 60068-2-64.
203 6.2 Method of mounting and orientation of equipment under test
204 For general mounting of components refer to IEC 60068-2-47.

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205 The equipment under test shall be mechanically connected to the test machine in a manner
206 representative of installation on the vehicle, either directly or using a fixture. Bolts and screws
207 shall be tightened to their nominal design torque, that shall be specified by the customer.
208 If resilient mounts are located at the fixing points, they can be removed from the equipment for
209 long-life test. They shall be kept in place for functional random vibration test and shock test.
210 In case of removing resilient mounts from the equipment for simulated long-life test, the
211 following shall be performed (see Figure 3):
212 - the transfer function of resilient mounts shall be established during functional random
213 vibration test;
214 - ASD level for simulated long-life test shall include the transfer function previously
215 established: ASDLong-life test = acceleration ratio² ×|H|×ASDfunctional test
218 Figure 3 – Management of resilient mounts during testing
220 Transfer function is defined by:
𝐴𝐴𝐴𝐴𝐴𝐴
𝑎𝑎
221 |𝐻𝐻| =� �
𝐴𝐴𝐴𝐴𝐴𝐴
𝑎𝑎
222 Where:
223 ASD is the acceleration spectrum density of the fixing points of the functional random
a1
224 vibration test (b)
225 ASD is the acceleration spectrum density of the measurement points of the functional
a2
226 random vibration test (b)
227 ASD , ASD and H shall be computed between f and f and with a common minimum
a1 a2 1 2
228 resolution Δf of 1 Hz.
229 The statistical error of ASD and ASD is recommended to be below 0.15, and is defined by:
a1 a2
oSIST prEN IEC 61373:2024
9/3019/CDV – 16 – IEC CDV 61373  IEC 2023
231 Where T (s) is the duration of the signal considered for ASD computation.
232 Figure 4 illustrates a graphical representation of a transfer function.
235 Figure 4 – Transfer function of resilient mounts
236 As the method of mounting can significantly influence the results obtained, the actual method
237 of mounting shall be clearly identified in the test report.
238 It is the responsibility of the user to verify that elastic mount removal does not affect the
239 mechanical resonance frequencies and the relevant modal shapes in structural parts of the
240 equipment.
241 Unless otherwise agreed it is preferred that the equipment shall be tested in its normal working
242 orientation with no special precautions taken against the effects of magnetic interference, heat
243 or any other factors upon the operation and performance of the equipment under test.
244 Wherever possible, the fixture device shall not have a resonance within the test frequency
245 range.
246 When resonances of the fixture device are unavoidable:
247 - The influence of the resonance on the performance of the equipment under test shall
248 be studied and identified in the report;
249 - Measurements shall be taken to ensure ASD levels conform to the standard at the
250 reference point (see 6.2.3).
251 6.3 Reference and check points
252 6.3.1 General
253 The test requirements are confirmed by measurements made at a reference point and, in certain
254 cases, at check points, related to the fixing points of the equipment.
255 In the case of large numbers of small items of equipment mounted on one fixture, the reference
256 and/or check points may be related to the fixture rather than to the fixing points of the equipment

oSIST prEN IEC 61373:2024
IEC CDV 61373  IEC 2023 – 17 – 9/3019/CDV
257 under test. In this case the lowest resonant frequency of the loaded fixture shall be higher than
258 the upper test frequency limit.
259 6.3.2 Fixing point
260 A fixing point is a part of the equipment under test in contact with the fixture or vibration testing
261 surface at a point where the equipment is normally fastened in service.
262 6.3.3 Check point
263 A check point shall be as close as possible to a fixing point and in any case shall be rigidly
264 connected to it. If no more than four fixing points exist, each one is defined as a check point. If
265 more than four fixing points exist, a minimum of four representative fixing points will be defined
266 in the relevant specification to be used as checkpoints. The vibration at these points shall not
267 fall below the specified minimum limits. All check points shall be identified in the test report. In
268 the case of small items of equipment where the size, weight and complexity of the mechanical
269 structure do not merit multipoint checking, the report shall identify how many check points were
270 used and their locations.
271 6.3.4 Reference point
272 The reference point is the single point from which the reference signal is obtained in order to
273 confirm the test requirements, and is taken to represent the motion of the equipment under test.
274 It may be a check point or a fictitious point created by manual or automatic processing of the
275 signals from the check points.
276 For random vibration if a fictitious point is used, the spectrum of the reference signal is defined
277 as the arithmetic mean at each frequency of the acceleration spectral density (ASD) values of
278 the signals from all check points. In this case, the total RMS value of the reference signal is
279 equivalent to the root mean square of the RMS values of the signals from
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