Electromechanical elementary relays - Part 2-1: Reliability - Procedure for the verification of B<sub>10</sub> values

IEC 61810-2-1:2017 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 document.
This edition includes the following significant technical changes with respect to the previous edition:
- limitation of tests to 10 M cycles in Clause 5;
- reduction of required number of test samples to 5 in specified cases;
- introduction of WeiBayes analysis for routine test under Clause 4.

Relais électromécaniques élémentaires - Partie 2-1: Fiabilité - Procédure de vérification des valeurs de B<sub>10</sub>

L'IEC 61810-2-1:2017 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 commande relatifs à la sécurité des machines selon l'IEC 62061 et l'ISO 13849-1. Pour ces relais, les valeurs de B10 pour des défaillances dangereuses (valeurs de B10D) sont obtenues à partir des essais spécifiés dans le présent document.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- limitation des essais à 10 M de manœuvres à l'Article 5;
- réduction du nombre exigé d'échantillons d'essai à 5 dans des cas spécifiés;
- introduction de l'analyse de WeiBayes pour l'essai individuel de série à l'Article 4.

General Information

Status
Published
Publication Date
29-May-2017
Current Stage
PPUB - Publication issued
Start Date
30-May-2017
Completion Date
30-May-2017
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IEC 61810-2-1
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electromechanical elementary relays –
Part 2-1: Reliability – Procedure for the verification of B values
Relais électromécaniques élémentaires –
Partie 2-1: Fiabilité – Procédure de vérification des valeurs de B
IEC 61810-2-1:2017-05(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61810-2-1
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electromechanical elementary relays –
Part 2-1: Reliability – Procedure for the verification of B values
Relais électromécaniques élémentaires –
Partie 2-1: Fiabilité – Procédure de vérification des valeurs de B
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.70 ISBN 978-2-8322-4389-3

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61810-2-1:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

3.2 Definitions related to tests ...................................................................................... 7

4 Verification of B ........................................................................................................... 7

4.1 General ................................................................................................................... 7

4.2 Requirements ......................................................................................................... 7

4.2.1 Test specimens ............................................................................................... 7

4.2.2 Test circuit ....................................................................................................... 8

4.2.3 Contact loads .................................................................................................. 8

4.2.4 Environmental conditions ................................................................................. 8

4.2.5 Operating conditions ........................................................................................ 8

4.2.6 Failure criteria ................................................................................................. 8

4.3 Performance of the tests ......................................................................................... 9

4.3.1 Type test ......................................................................................................... 9

4.3.2 Routine test ..................................................................................................... 9

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 ................................................................................................ 11

5.2.4 Environmental conditions ............................................................................... 11

5.2.5 Operating conditions ...................................................................................... 11

5.2.6 Failure criteria ............................................................................................... 11

5.3 Performance of the tests ....................................................................................... 12

5.3.1 Type test ....................................................................................................... 12

5.3.2 Routine test ................................................................................................... 12

Annex A (informative) Example illustrating the assessment of malfunctions for B
10D

evaluation ............................................................................................................................. 15

A.1 Purpose ................................................................................................................ 15

A.2 Basic assumptions ................................................................................................ 15

A.3 Example................................................................................................................ 15

A.4 Evaluation ............................................................................................................. 16

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

---------------------- Page: 4 ----------------------
IEC 61810-2-1:2017 © IEC 2017 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMECHANICAL ELEMENTARY RELAYS –
Part 2-1: Reliability – Procedure for the verification of B values
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

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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

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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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.

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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 second edition cancels and replaces the first edition published in 2011. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) limitation of tests to 10 M cycles in Clause 5;
b) reduction of required number of test samples to 5 in specified cases;
c) introduction of WeiBayes analysis for routine test under Clause 4.
---------------------- Page: 5 ----------------------
– 4 – IEC 61810-2-1:2017 © IEC 2017
The text of this International Standard is based on the following documents:
FDIS Report on voting
94/416/FDIS 94/419/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 61810-2:2017.

A list of all parts in the IEC 61810 series, published under the general title Electromechanical

elementary relays, 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.
---------------------- Page: 6 ----------------------
IEC 61810-2-1:2017 © IEC 2017 – 5 –
INTRODUCTION

Based on the general provisions of IEC 61810-2, this part of IEC 61810 specifies reliability

test procedures for electromechanical elementary relays where enhanced requirements for

the verification of reliability apply. A type test is passed and then confirmed by routine tests

with specified periodicity. This document describes how figures for B (the 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

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

"dangerous" mode. For the calculation of MTTF for electromechanical relays, the data

provided by the manufacturer for B can be used (see Clause C.4 of ISO 13849-1:2015).

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 13849-1:2015.

NOTE Requirements for such relays are given in IEC 61810-3.
---------------------- Page: 7 ----------------------
– 6 – IEC 61810-2-1:2017 © IEC 2017
ELECTROMECHANICAL ELEMENTARY RELAYS –
Part 2-1: Reliability – Procedure for the verification of B values
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

machinery in accordance with IEC 62061 and ISO 13849-1. For such relays, B values for

dangerous failures (B values) are derived from the tests specified in this document.

10D
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 61810-1:2015, Electromechanical elementary relays – Part 1: General and safety

requirements
IEC 61810-2:2017, Electromechanical elementary relays – Part 2: Reliability

IEC 61810-3, Electromechanical elementary relays – Part 3: Relays with forcibly guided

(mechanically linked) contacts

IEC 62061, Safety of machinery – Functional safety of safety-related electrical, electronic and

programmable electronic control systems

ISO 13849-1:2015 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 IEC 61810-2 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
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

[SOURCE: ISO 13849-1:2015, 3.1.5, modified – In the definition, the abbreviated term

"SRP/CS" has been replaced by "safety-related part of a control system".]
---------------------- Page: 8 ----------------------
IEC 61810-2-1:2017 © IEC 2017 – 7 –
3.2 Definitions related to tests
3.2.1
type test

conformity test made on sample representative of the production to get basic performance

data or to verify that these relays comply with the specified requirements
[SOURCE: IEC 61810-2:2017, 3.21.1]
3.2.2
routine test

conformity test made on sample without any modifications and specification changes during or

after mass production with specified repetition

Note 1 to entry: The results from routine tests are used to verify that the level of technical performance is

maintained.
[SOURCE: IEC 61810-2:2017, 3.21.2, modified – The note has been added.]
4 Verification of B
4.1 General

Clause 4 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 change-over contact;
• insulation failure of the relay.

From a type test, a value for B is obtained that indicates the probability of the occurrence of

a relay failure. The value for B is given in numbers of cycles.

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

carried out by routine 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 in accordance with IEC 61810-2.
---------------------- Page: 9 ----------------------
– 8 – IEC 61810-2-1:2017 © IEC 2017
4.2.2 Test circuit

The test circuit described in Annex C of IEC 61810-1:2015 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 61810-1:2015 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 5.8 of IEC 61810-1:2015 or

inductive loads according to Annex B of IEC 61810-1:2015.
4.2.4 Environmental conditions

The conditions of Table 1 of IEC 61810-1:2015 apply. However, an extended ambient

temperature range of 18 °C to 40 °C is permitted.
4.2.5 Operating conditions
The provisions of 5.3 of IEC 61810-2:2017 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 2/3 of the tested

relays shall fail, or each test specimen shall reach a lifetime of 10 M cycles.
For the assessment of recorded malfunctions severity B according to Clause 6 of
IEC 61810-2:2017 applies. The dielectric test is performed
• between coil and contacts,
• between adjacent contacts, and
• across open contacts.

A contact that fails to open cannot be tested for compliance with the requirements for open

contacts.

The insulation requirements shall be verified according to 11.4 of IEC 61810-1:2015. This 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.
---------------------- Page: 10 ----------------------
IEC 61810-2-1:2017 © IEC 2017 – 9 –
4.3 Performance of the tests
4.3.1 Type test

The type 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. For the purpose of

the following routine test according to 4.3.2.3, the shape parameter β and the characteristic

life shall be evaluated according to IEC 61810-2.

After completion of a type test, the first routine test shall be initiated for verification in

accordance with the periodicity specified under 4.3.2.
4.3.2 Routine test
4.3.2.1 General

The routine test shall be performed in regular intervals as specified by the manufacturer.

4.3.2.2 Routine test with Weibull

The test shall be performed with at least 5 relays, and B value shall be determined in

accordance with IEC 61810-2.
4.3.2.3 Routine test with WeiBayes

The test shall be performed with at least 5 relays, and B value shall be determined in

accordance with IEC 61810-2. In the event of deviation from 4.2.6, the test is stopped with no

failures recorded (WeiBayes without failure), and a WeiBayes confidence level of 90 % shall

be achieved.
4.3.2.4 Acceptance criteria of routine test

For each routine test, the evaluated B value shall be at least 80 % of the B value obtained

10 10

from the type test. For the routine test with WeiBayes, the B value obtained shall be at least

90 % of that of the type test.

NOTE 1 This requirement is intended to take into account possible variations for the routine tests.

NOTE 2 In IEC 61810-2 the WeiBayes result is determined using the characteristic life result from the initial

Weibull test. Accordingly, here the acceptance of the routine test can be evaluated by comparing the characteristic

life values of the initial Weibull and the WeiBayes from the routine test.

In the event that these requirements are not met, suitable corrective actions have to be taken

to remove the failure causes. The routine test shall be repeated with appropriately modified

test specimens. If it is not possible to achieve a positive routine test with non-constructive

corrective actions, constructional changes to the relay (e.g. new contact material, dimensional

changes of contact) are necessary, and the modified relay shall be regarded as a new

construction, and a new independent test procedure starting a with type test shall be

performed.
5 Evaluation and verification of B
10D
5.1 General

Clause 5 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.
---------------------- Page: 11 ----------------------
– 10 – IEC 61810-2-1:2017 © IEC 2017

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 change-over 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 13849-2:2012).

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 contacts and break contacts 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 13849-1:2015. Electromechanical elementary relays with

forcibly guided (mechanically linked) contacts are specified in IEC 61810-3.

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 13849-2:2012, 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 a dangerous failure, the

manufacturer shall record during the test any malfunction (in number of cycles and type of

malfunction). This allows them to evalua
...

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