IEC 61810-2-1:2011

Electromechanical elementary relays - Part 2-1: Reliability - Procedure for the verification of B₁₀ values

IEC 61810-2-1:2011 specifies reliability test procedures for electromechanical elementary relays when enhanced requirements for the verification of reliability apply. Particular provisions are given for relays incorporated in safety-related control systems of machinery in accordance with IEC 62061 and ISO 13849-1. For such relays B10 values for dangerous failures (B10d values) are derived from the tests specified in this standard.
This publication is to be read in conjunction with IEC 61810-2:2011.

Relais électromécaniques élémentaires - Partie 2-1: Fiabilité - Procédure de vérification des valeurs de B₁₀

La CEI 61810-2-1:2011 spécifie les procédures d'essai de fiabilité pour les relais électromécaniques élémentaires lorsque des exigences renforcées pour la vérification de la fiabilité s'appliquent. Des dispositions particulières sont fournies pour les relais incorporés dans les systèmes de contrôle liés à la sécurité des machines selon la CEI 62061 et l'ISO 13849-1. Pour ces relais, les valeurs de B10 pour des défaillances dangereuses (valeurs de B10d) sont dérivées des essais spécifiés dans la présente norme.
Cette publication doit être lue conjointement avec la CEI 61810-2:2011.

General Information

• Status: Published
• Publication Date: 24-Feb-2011
• ICS: 17.240 - Radiation measurements
• ICS: 27.120 - Nuclear energy engineering
• ICS: 29.120.70 - Relays
• Technical Committee: TC 94 - Electrical relays
• Drafting Committee: WG 3 - TC 94/WG 3
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 30-May-2017

Relations

• Revised: IEC 61810-2-1:2017 - Electromechanical elementary relays - Part 2-1: Reliability - Procedure for the verification of B₁₀ values
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61810-2-1
®

Edition 1.0 2011-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Electromechanical elementary relays –
Part 2-1: Reliability – Procedure for the verification of B values
10

Relais électromécaniques élémentaires –
Partie 2-1: Fiabilité – Procédure de vérification des valeurs de B
10

IEC 61810-2-1:2011

---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61810-2-1
®

Edition 1.0 2011-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Electromechanical elementary relays –
Part 2-1: Reliability – Procedure for the verification of B values
10

Relais électromécaniques élémentaires –
Partie 2-1: Fiabilité – Procédure de vérification des valeurs de B
10

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX Q
ICS 29.120.70 ISBN 978-2-88912-375-9

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 61810-2-1  IEC:2011
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Verification of B . 7
10
4.1 General . 7
4.2 Requirements . 7
4.2.1 Test specimens . 7
4.2.2 Test circuit . 7
4.2.3 Contact loads . 7
4.2.4 Environmental conditions . 7
4.2.5 Operating conditions . 8
4.2.6 Failure criteria . 8
4.3 Performance of the tests . 8
4.3.1 Conformity test . 8
4.3.2 Periodic test . 8
5 Evaluation and verification of B . 9
10d
5.1 General . 9
5.2 Requirements . 10
5.2.1 Test specimens . 10
5.2.2 Test circuit . 10
5.2.3 Contact loads . 10
5.2.4 Environmental conditions . 10
5.2.5 Operating conditions . 10
5.2.6 Failure criteria . 10
5.3 Performance of the tests . 11
5.3.1 Conformity test . 11
5.3.2 Periodic test . 11
Annex A (informative) Example illustrating the assessment of malfunctions for B
10d
evaluation . 15
Bibliography . 17

Figure 1 – Schematic flowchart . 13
Figure 2 – Schematic flowchart for relays where dangerous failures have to be
assessed . 14

Table A.1 – Example with number of cycles at which malfunctions have been recorded . 15

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61810-2-1  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 2-1: Reliability –
Procedure for the verification of B values
10


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
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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 61810-2-1 has been prepared by IEC technical committee 94: All-
or-nothing electrical relays.
This standard cancels and replaces IEC/PAS 61810-2-1 published in 2008. This edition
constitutes a technical revision.
This standard includes the following significant technical changes with respect to
IEC/PAS 61810-2-1:
• addition of inductive loads in Clause 4;
• specification of dielectric tests under Clause 4 and Clause 5;
.
• addition of informative Annex A illustrating the assessment of malfunctions for B
10d

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– 4 – 61810-2-1  IEC:2011
The text of this standard is based on the following documents:
FDIS Report on voting
94/317/FDIS 94/326/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61810 series can be found, under the general title
Electromechanical elementary relays, on the IEC website.
This International Standard is to be used in conjunction with IEC 61810-2:2011.
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.

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61810-2-1  IEC:2011 – 5 –
INTRODUCTION
Based on the general provisions of IEC 61810-2, this standard specifies reliability test
procedures for electromechanical elementary relays where enhanced requirements for the
verification of reliability apply. An initial conformity test is passed and then confirmed by
periodic tests with specified periodicity. This standard describes how figures for B (the
10
mean number of cycles until 10 % of the relays have failed) are derived from these life tests
performed with representative relay samples.
In particular when electromechanical elementary relays are intended to be incorporated in
safety-related control systems of machinery in accordance with IEC 62061 and ISO 13849-1,
the mean time to dangerous failure (MTTF ) is a measure that can be taken into account
d
when assessing the probability of dangerous failure of the safety function concerned.
Although a component failure cannot be defined as “dangerous” unless the detailed
application is known, it is common to consider a failure mode that is likely to result in danger
in a typical application of the component, and to refer to this failure mode as a “dangerous
failure”. The MTTF then becomes the expectation of the mean time to failure in this
d
“dangerous“ mode. For the calculation of MTTF for electromechanical relays the data
d
provided by the manufacturer for B can be used (see C.4 of ISO 13849-1:2006).
10d
Electromechanical elementary relays with forcibly guided (mechanically linked) contacts offer
the possibility of a high diagnostic coverage according to 4.5.3 of ISO 13849-1:2006.
NOTE Requirements for such relays are given in EN 50205.

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– 6 – 61810-2-1  IEC:2011
ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 2-1: Reliability –
Procedure for the verification of B values
10



1 Scope
This part of IEC 61810 specifies reliability test procedures for electromechanical elementary
relays when enhanced requirements for the verification of reliability apply.
Particular provisions are given for relays incorporated in safety-related control systems of
values for
machinery in accordance with IEC 62061 and ISO 13849-1. For such relays B
10
dangerous failures (B values) are derived from the tests specified in this standard.
10d
This International Standard is only intended to be used in conjunction with IEC 61810-2.
2 Normative references
The following referenced documents are indispensable for the application 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 61810-1:2008, Electromechanical elementary relays – Part 1: General requirements
IEC 61810-2:2011, Electromechanical elementary relays – Part 2: Reliability
IEC 62061:2005, Safety of machinery – Functional safety of safety-related electrical,
electronic and programmable electronic control systems
ISO 13849-1:2006, Safety of machinery – Safety-related parts of control systems – Part 1:
General principles for design
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the IEC 61810-2, as well
as the following apply.
3.1
dangerous failure
failure which has the potential to put the safety-related part of a control system in a hazardous
or fail-to-function state
[ISO 13849-1:2006, 3.1.5, modified]
3.2
conformity test
test of a sample of relays made to a given design to verify that these relays comply with the
specified requirements
3.3
periodic test
test carried out periodically on a sample of relays drawn from running production

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61810-2-1  IEC:2011 – 7 –
NOTE The results from periodic tests are used to verify that the level of technical performance is maintained.
4 Verification of B
10
4.1 General
This clause specifies requirements where the reliability of the relay has to be assessed and
verified.
This procedure is applicable to relays where wearout mechanisms prevail.
NOTE 1 For relays where random failures prevail, provisions are under consideration.
NOTE 2 For relays intended to be used in safety-related control systems of machinery, the provisions of Clause 5
are applicable.
The following failure modes can occur:
• failure to open of a relay contact;
• failure to close of a relay contact;
• unintended bridging of a changeover contact;
• insulation failure of the relay.
From a conformity test, a value for B is obtained that indicates the probability of the
10
occurrence of a relay failure. The value for B is given in numbers of cycles.
10
NOTE 3 With the knowledge of the frequency of operation (cycling rate) of the relay within a specific application
the number of cycles can be transformed into respective times.
Verification that this B value is applicable to relays from the series production shall be
10
carried out by periodic tests.
An overview of this procedure is given in Figure 1.
4.2 Requirements
4.2.1 Test specimens
The test shall be carried out with 10 relays in accordance with IEC 61810-2.
4.2.2 Test circuit
The test circuit described in Annex C of IEC 61810-1:2008 shall be used, unless otherwise
specified by the manufacturer and explicitly indicated in the test report. When feasible, one of
the circuits in accordance with Annex D of IEC 61810-1:2008 is to be used.
4.2.3 Contact loads
The contact loads shall be specified by the manufacturer and indicated in the test report. It is
recommended to select appropriate resistive loads according to 5.7 of IEC 61810-1:2008 or
inductive loads according to Annex B of IEC 61810-1:2008.
4.2.4 Environmental conditions
The conditions of Table 1 of IEC 61810-1:2008 apply. However, an extended ambient
temperature range of 18 °C to 40 °C is permitted.

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– 8 – 61810-2-1  IEC:2011
4.2.5 Operating conditions
The provisions of 5.3 of IEC 61810-2:2011 apply.
Unless otherwise specified by the manufacturer, each cycle of the coil energization shall be
1 s ON and 9 s OFF.
The test is performed without coil suppression, unless explicitly specified.
4.2.6 Failure criteria
Generally the test is to be continued until all test specimens have failed. When the test is
truncated at a specific number of cycles, all relays that have not yet failed are considered to
fail at that number of cycles (worst case assumption). However, at least 7 of the tested relays
shall fail physically.
For the assessment of recorded malfunctions severity B according to Clause 6 of
IEC 61810-2:2011 applies. The dielectric test is performed:
• between coil and contacts;
• between adjacent contacts;
• across open contacts.
NOTE A contact that fails to open cannot be tested for compliance with the requirements for open contacts.
The verification of insulation requirements according to Clause 11 of IEC 61810-1:2008 (with
75 % of the initial voltage for the dielectric test specified under 10.3 of IEC 61810-1:2008)
may be performed in either of the following ways:
a) during the test, the dielectric test is performed periodically at given numbers of cycles.
When the relay does not pass the dielectric test, the number of cycles for the previous
dielectric test that has been passed is considered as the cycles to failure value for this
individual relay;
b) in the case that no periodical monitoring according to item a) is performed, the
dielectric test shall be made when a relay under test fails due to a functional contact
failure (see 4.1). If the relay does not comply with the dielectric test, the whole test is
not passed. The same applies when the test is truncated at a certain number of cycles.
4.3 Performance of the tests
4.3.1 Conformity test
The conformity test is carried out with a sample of 10 relays. Each failure shall be recorded.
The B value is evaluated based on the procedure given in IEC 61810-2.
10
After completion of a conformity test, the first periodic test shall be initiated for verification in
accordance with the periodicity specified under 4.3.2.
4.3.2 Periodic test
The periodic test shall be performed in regular intervals as specified by the manufacturer.
For each periodic test, the evaluated B value shall be at least 80 % of the B value
10 10
obtained from the conformity test.
NOTE This requirement is intended to take into account possible variations for the periodic tests.

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61810-2-1  IEC:2011 – 9 –
In case these requirements are not met, suitable corrective actions have to be taken to
remove the failure causes. The complete conformity test shall be repeated with appropriately
modified test specimens or adapted contact loads (e.g. reduced switching current).
5 Evaluation and verification of B
10d
5.1 General
This clause specifies requirements for relays intended to be used in safety-related control
systems of machinery in accordance with IEC 62061 and ISO 13849-1. For this purpose
Clause 4 does not apply.
This procedure is applicable to relays where wearout mechanisms prevail.
NOTE 1 For relays where random failures prevail, provisions are under consideration.
The following failure modes can occur:
• failure to open of a relay contact;
• failure to close of a relay contact;
• unintended bridging of a changeover contact;
• insulation failure of the relay.
NOTE 2 The term “unintended bridging of a changeover contact” is equivalent to “simultaneous short-circuit
between the three terminals of a changeover contact” (used in Table D.9 of ISO 13849-2:2006).
For a given application it has to be assessed which of the above listed failure mode(s) is (are)
to be considered as dangerous failure(s).
Simultaneous closing of make contact(s) and break contact(s) is excluded if forcibly guided
(mechanically linked) contacts are used which offer the possibility of a high diagnostic
coverage according to 4.5.3 of ISO 13849-1:2006. Electromechanical elementary relays with
forcibly guided (mechanically linked) contacts are specified in EN 50205.
NOTE 3 In typical applications, the failure to open of a make contact and the insulation failure are dangerous
failure modes (see 7.2.2 and Table D.1 of ISO 13849-2:2003, where basic safety principles are compiled, in
particular the use of de-energisation with a normally open (make) contact for relays to achieve a system safe
state).
Where it is not clear which failure mode is to be considered as dangerous failure, the
manufacturer shall record during the test any malfunction (in number of cycles and type of
malfunction). This allows him to evaluate B values for any failure mode after the test has
10
been completed.
From a conformity test, a value for B is obtained that indicates the probability of the
10d
occurrence of a dangerous failure. This value is given in number of cycles.
NOTE 4 With the knowledge of the frequency of operation (cycling rate) of the relay within a specific application,
the number of cycles can be transformed into respective times.
Verification that these B values are applicable to relays from the series production shall be
10d
carried out by periodic tests.
An overview of this procedure is given in Figure 2.

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– 10 – 61810-2-1  IEC:2011
5.2 Requirements
5.2.1 Test specimens
The test shall be carried out with 10 relays for each contact load rating in accordance with
IEC 61810-2. In case of relays with several contacts, those two contacts - of the same type
(e.g. two make contacts) if available - shall be tested which are considered as most critical
with respect to a possible insulation failure.
NOTE In general, adjacent contacts are the most critical ones.
5.2.2 Test circuit
The test circuit described in Annex C of IEC 61810-1:2008 shall be used, unless otherwise
specified by the manufacturer and explicitly indicated in the test report. When feasible, one of
the circuits in accordance with Annex D of IEC 61810-1:2008 is to be used.
5.2.3 Contact loads
The contact loads shall be specified by the manufacturer and indicated in the test report. It is
recommended to select load types according to Annex B (endurance test) of IEC 61810-1.
Unless otherwise specified, the conformity test shall be carried out for AC inductive load with
230 V and for DC inductive load with 24 V, respectively, with the following load currents:
• I
e
• I /2
e
/4
• I
e
with I = rated operating current.
e
NOTE In general, the periodic test is made with I only (see 5.3.2).
e
5.2.4 Environmental conditions
The conditions of Table 1 of IEC 61810-1:2008 apply. However, an ambient temperature
range of 18 °C to 40 °C is permitted.
5.2.5 Operating conditions
The provisions of 5.3 of IEC 61810-2:2011 apply.
Unless otherwise specified by the manufacturer, each cycle of the coil energization shall be
1 s ON and 9 s OFF.
The test is performed without coil suppression, unless explicitly specified.
5.2.6 Failure criteria
The test shall be continued until all test specimens have failed.
For the assessment of recorded malfunctions in accordance with Clause 6 of
IEC 61810-2:2011, the following applies:
• for malfunctions related to a dangerous failure mode: severity A;
• for other malfunctions: severity B.
The verification of insulation requirements according to Clause 11 of IEC 61810-1:2008 (with
75 % of the initial voltage for the dielectric test specified under 10.3 of IEC 61810-1:2008)
shall be performed when a relay under test fails due to a functional contact failure (see 5.1).
The dielectric test is performed:

---------------------- Page: 12 ----------------------
61810-2-1  IEC:2011 – 11 –
• between coil and contacts;
• between adjacent contacts;
• across open contacts.
NOTE A contact that fails to open cannot be tested for compliance with the requirements for open contacts.
If the relay does not comply with the dielectric test, the whole test is not passed.
5.3 Performance of the tests
5.3.1 Conformity test
The conformity test is carried out with a sample of 10 relays for each contact load rating.
Each failure shall be recorded. The dangerous failures are registered separately.
In the first step the B value is evaluated based on the procedure given in IEC 61810-2
10
taking into account all registered failures (see also Annex A for a schematic example).
The B value is derived as follows:
10d
B = B × 10/N
10d 10 d
with
10 = number of tested relays;
N = number of registered dangerous failures.
d
NOTE When no dangerous failure has been registered, N = 1 is assumed.
d
Example:
From data obtained with a life test of 10 relays, a B value has been derived:
10
5
B = 6 × 10 cycles
10
Duri
...