SIST EN IEC 63522-48:2025

Electrical relays - Tests and measurements - Part 48: Contact failure rate test

IEC 63522-48:2024 is used for for testing electromechanical elementary relays (electromechanical relays, reed relays, reed contacts, reed switches and technology combinations of these) and for evaluating their ability to perform under expected conditions of transportation, storage and all aspects of operational use.
This document defines a standard test method for contact failure rate test of electromechanical elementary relays applied to low-load applications (e.g., CC 0, CC 1) and failure rates and failure rate levels at low loads under specified conditions.

Elektrische Relais - Prüfungen und Messungen - Teil 48: Prüfung der Kontaktausfallrate

Relais électriques - Essais et mesurages - Partie 48: Essai de taux de défaillance des contacts

Le IEC 63522-48:2024 traite des essais des relais électromécaniques élémentaires (relais électromécaniques, relais à lames souples, contacts à lames souples, interrupteurs à lames souples et combinaisons de ces technologies) et évalue leur aptitude à fonctionner dans des conditions prévues de transport, de stockage, et tous les aspects de leur utilisation opérationnelle.
Le présent document définit une méthode d’essai normalisée pour l'essai de taux de défaillance des contacts des relais électromécaniques élémentaires dans le cas d'applications à faible charge (par exemple, CC 0, CC 1) et de taux de défaillance et de niveaux de taux de défaillance à faibles charges dans des conditions spécifiées.

Električni releji - Preskusi in meritve - 48. del: Delež neuspešnih preskusov

Ta del standarda IEC 63522 se uporablja za preskušanje elektromehanskih osnovnih relejev (elektromehanskih relejev, relejev reed, kontaktov reed, stikal reed in njihovih tehnoloških kombinacij) in ocenjevanje njihove zmožnosti delovanja v pričakovanih pogojih med transportom in skladiščenjem ter v vseh vidikih operativne uporabe.
Ta dokument določa standardno preskusno metodo za delež neuspelih preskusov elektromehanskih osnovnih relejev, namenjenih za uporabo pri nizkih obremenitvah (npr. CC 0, CC 1), ter deleže in stopnje neuspešnosti pri nizkih obremenitvah v določenih pogojih.

General Information

• Status: Published
• Publication Date: 20-Mar-2025
• ICS: 29.120.70 - Relays
• Technical Committee: ISS EIT.ERE - All-or-nothing electrical relays
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 05-Feb-2025
• Due Date: 12-Apr-2025
• Completion Date: 21-Mar-2025
• Ref Project: EN IEC 63522-48:2025 - Electrical relays - Tests and measurements - Part 48: Contact failure rate test

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2025
Električni releji - Preskusi in meritve - 48. del: Delež neuspešnih preskusov
Electrical relays - Tests and measurements - Part 48: Contact failure rate test
Elektrische Relais - Prüfungen und Messungen - Teil 48: Prüfung der Kontaktausfallrate
Relais électriques - Essais et mesurages - Partie 48: Essai de taux de défaillance des
contacts
Ta slovenski standard je istoveten z: EN IEC 63522-48:2025
ICS:
29.120.70 Releji Relays
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 63522-48

NORME EUROPÉENNE
EUROPÄISCHE NORM January 2025
ICS 29.120.70
English Version
Electrical relays - Tests and measurements - Part 48: Contact
failure rate test
(IEC 63522-48:2024)
Relais électriques - Essais et mesurages - Partie 48 : Essai Elektrische Relais - Prüfungen und Messungen - Teil 7-48:
de taux de défaillance des contacts Prüfung der Kontaktausfallrate
(IEC 63522-48:2024) (IEC 63522-48:2024)
This European Standard was approved by CENELEC on 2025-01-09. 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,
Türkiye 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
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 63522-48:2025 E

European foreword
The text of document 94/1039/FDIS, future edition 1 of IEC 63522-48, prepared by TC 94 "Electrical
relays" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-01-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-01-31
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 63522-48:2024 was approved by CENELEC as a European
Standard without any modification.
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.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60605-4 2001 Equipment reliability testing - Part 4: - -
Statistical procedures for exponential
distribution - Point estimates, confidence
intervals, prediction intervals and tolerance
intervals
IEC 61810-1 - Electromechanical elementary relays - Part EN 61810-1 -
1: General and safety requirements
IEC 61810-2 - Electromechanical elementary relays - Part EN 61810-2 -
2: Reliability
IEC 61810-4 - Electromechanical elementary relays - Part EN IEC 61810-4 -
4: General and safety requirements for
reed relays
IEC 62246-1 - Reed switches - Part 1: Generic EN 62246-1 -
specification
IEC 62246-1-1 2018 switches – Part 1-1: Generic specification - EN IEC 62246-1-1 2018
Blank detail specification
IEC 62246-4 2023 Reed switches - Part 4: Application in EN IEC 62246-4 2023
conjunction with magnetic actuator used
for magnetic sensing devices
1 2
IEC 63522-0 — Electrical relays - Tests and Measurements EN IEC 63522-0 —
- Part 0: General and Guidance
3 4
IEC 63522-6 - Electrical relays - Tests and measurements EN IEC 63522-6 -
- Part 6: Contact-circuit resistance (or
voltage drop)
Under preparation. Stage at the time of publication: IEC CDV 63522-0:2024.
Under preparation. Stage at the time of publication: prEN IEC 63522-0:2024.
Under preparation. Stage at the time of publication: IEC FDIS 63522-6:2024.
Under preparation. Stage at the time of publication: FprEN IEC 63522-6:2024.
Publication Year Title EN/HD Year
5 6
IEC 63522-7 - Electrical relays - Tests and measurements EN IEC 63522-7 -
- Part 7: Functional tests
7 8
IEC 63522-45 — Electrical relays - Tests and measurements EN IEC 63522-45 —
- Part 45: Maximum frequency of operation

Under preparation. Stage at the time of publication: IEC BPUB 63522-7:2024.
Under preparation. Stage at the time of publication: FprEN IEC 63522-7:2024.
Under preparation. Stage at the time of publication: IEC FDIS 63522-45:2024.
Under preparation. Stage at the time of publication: FprEN IEC 63522-45:2024.
IEC 63522-48 ®
Edition 1.0 2024-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical relays – Tests and measurements –

Part 48: Contact failure rate test

Relais électriques – Essais et mesurages –

Partie 48 : Essai de taux de défaillance des contacts

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.70  ISBN 978-2-8327-0061-7

– 2 – IEC 63522-48:2024 © IEC 2024
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
3.1 Terms and definitions related to failure rate . 7
3.2 Terms and definitions related to conditions and operations . 8
3.3 Terms and definitions related to contact faults . 8
4 Test procedure . 8
4.1 Purpose . 8
4.2 Procedure . 8
4.2.1 General . 8
4.2.2 Test circuit . 9
4.2.3 Contact load . 9
4.2.4 Test cycle . 10
4.2.5 Method 1: Continuous monitoring . 10
4.2.6 Method 2: Intermediate monitoring . 11
4.3 Conditions to be specified . 11
5 Evaluation . 12
5.1 General . 12
5.1.1 Acceptance criteria . 12
5.1.2 Final tests (if applicable) . 12
5.1.3 Visual inspection (if applicable) . 12
5.2 Test report . 13
Annex A (informative) Test procedures for electromechanical elementary relays . 14
Annex B (normative) Test procedures for particular reed switch (reed contact) types
and similar products . 16
Annex C (normative) Test circuits for contact failure rate test . 18
C.1 Test circuit with monitoring equipment using relays . 18
C.2 Test circuit with monitoring equipment using a monitoring device with
capability of storing measurement results . 19
C.3 ON check and OFF check timing portion . 19
Annex D (normative) Assessment of test results . 20
D.1 General . 20
D.2 Calculation of upper limit value of failure rate. 20
D.3 Calculation of total number of operations . 21
D.4 Failure rate level . 22
Annex E (informative) Practical example . 24
E.1 Purpose . 24
E.2 Basic assumptions . 24
E.3 Example. 24
Bibliography . 26

Figure C.1 – Test circuit with monitoring equipment using relays . 18
Figure C.2 – Test circuit with monitoring equipment using a monitoring device with
capability of storing measurement results . 19
Figure C.3 – ON check and OFF check timing portion . 19

IEC 63522-48:2024 © IEC 2024 – 3 –
Figure D.1 – Example of test results in the case of fixed number testing plan . 22

Table 1 – Contact load characteristics . 9
Table 2 – Recommended test current . 9
Table 3 – Recommended test voltage . 10
Table 4 – Recommended number of testing cycles . 10
Table 5 – Recommended value of contact-circuit resistance . 11
Table A.1 – Test procedures for electromechanical elementary relays . 15
Table B.1 – Test procedures for particular reed switch (reed contact) types and similar
products. 17
Table D.1 – Coefficient k for calculating failure rate . 21
Table D.2 – Failure rate level . 22
Table D.3 – Acceptable number and total testing cycles (number of testing cycles) . 23
Table E.1 – Example with number of cycles at which ON failures have been recorded . 24

– 4 – IEC 63522-48:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL RELAYS –
TESTS AND MEASUREMENTS –
Part 48: Contact failure rate test

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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 63522-48 has been prepared by IEC technical committee 94: Electrical relays. It is an
International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
94/1039/FDIS 94/1084/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

IEC 63522-48:2024 © IEC 2024 – 5 –
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of IEC 63522 series, published under the general title Electrical relays ─ Tests
and measurements, 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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
– 6 – IEC 63522-48:2024 © IEC 2024
ELECTRICAL RELAYS –
TESTS AND MEASUREMENTS –
Part 48: Contact failure rate test

1 Scope
This part of IEC 63522 is used for testing electromechanical elementary relays
(electromechanical relays, reed relays, reed contacts, reed switches and technology
combinations of these) and for evaluating their ability to perform under expected conditions of
transportation, storage and all aspects of operational use.
This document defines a standard test method for contact failure rate test of electromechanical
elementary relays applied to low-load applications (for example, CC 0, CC 1) and failure rates
and failure rate levels at low loads under specified conditions.
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 60605-4:2001, Equipment reliability testing – Part 4: Statistical procedures for exponential
distribution – Point estimates, confidence intervals, prediction intervals and tolerance intervals
IEC 61810-1, Electromechanical elementary relays – Part 1: General and safety requirements
IEC 61810-2, Electromechanical elementary relays – Part 2: Reliability
IEC 61810-4, Electromechanical elementary relays – Part 4: General and safety requirements
for reed relays
IEC 62246-1, Reed switches – Part 1: Generic specification
IEC 62246-1-1:2018, Reed switches – Part 1-1: Generic specification – Blank detail
specification
IEC 62246-4:2023, Reed switches – Part 4: Application in conjunction with magnetic actuator
used for magnetic sensing devices
IEC 63522-0:–, Electrical relays – Tests and measurements – Part 0: General and guidance
IEC 63522-6, Electrical relays – Tests and measurements – Part 6: Contact-circuit resistance
(or voltage drop)
___________
Under preparation. Stage at the time of publication: IEC CDV 63522-0:2024.
Under preparation. Stage at the time of publication: IEC FDIS 63522-6:2024.

IEC 63522-48:2024 © IEC 2024 – 7 –
IEC 63522-7, Electrical relays – Tests and measurements – Part 7: Functional tests
IEC 63522-45:–, Electrical relays – Tests and measurements – Part 45: Maximum frequency of
operation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61810-1, IEC 61810-2,
IEC 63522-0, IEC 62246-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Terms and definitions related to failure rate
3.1.1
failure rate
number of failures relative to the number of cycles of service of the relay
Note 1 to entry: λ is the reciprocal of MTBF
c c.
[SOURCE: IEC 60050-444:2002, 444-07-09]
3.1.2
failure rate level
accumulated number of non-conforming units under specified operating conditions and
specified accumulated time (cycles), evaluated for a given confidence level
Note 1 to entry: Higher (lower) failure rate level: This term describes a failure rate level associated with a higher
(lower) number of failures per unit time (cycle).
3.1.3
confidence level
probability expressed in percentage (%) that a lot with a failure rate in the failure rate level of
will be rejected
3.1.4
total testing cycles
total number of operations
sum of test cycles or of numbers of operations spent or done on all DUTs
Note 1 to entry: Total test cycles is called component hour, sometimes.
___________
Under preparation. Stage at the time of publication: IEC BPUB 63522-7:2024.
Under preparation. Stage at the time of publication: IEC FDIS 63522-45:2024.

– 8 – IEC 63522-48:2024 © IEC 2024
3.2 Terms and definitions related to conditions and operations
3.2.1
internal impedance
impedance that exists between the output terminal of the power supply and the internal power
supply circuit
Note 1 to entry: Z < 0,02 Z (AC), R < 0,02 R (DC) at Contact category 0 and 1 (see Figure A.1 of
s M,B s M,B
IEC 63522-0:─ ).
[SOURCE: IEC 60050-312:2001, 312-06-19, modified – modified output impedance of the term
to internal impedance, rewording of the definition and addition of Note 1 to entry.]
3.3 Terms and definitions related to contact faults
3.3.1
contact fault due to increased contact-circuit resistance
occurrence of a contact-circuit resistance of a closed contact exceeding the maximum value
specified
[SOURCE: IEC 60050-444:2002, 444-07-13]
3.3.2
contact fault due to non-opening of the contact circuit
occurrence of a resistance across an open contact falling below the minimum value specified
[SOURCE: IEC 60050-444:2002, 444-07-14]
4 Test procedure
4.1 Purpose
This test is intended to investigate the failure rates or failure rate levels of the DUTs at low
loads under specified conditions.
NOTE 1 The failure data typically shows an exponential distribution.
NOTE 2 With respect to the establishment and assessment for relays of reliability data which typically show a
Weibull distribution, reference is made to IEC 61810-2.
The contact failure rate test evaluates random failures including those occurring in the range of
minimum operational voltage and current to clarify low-load application limits.
NOTE 3 For example, the intended use of low-level current swi
...