IEC 61810-3:2015

Electromechanical elementary relays - Part 3: Relays with forcibly guided (mechanically linked) contacts

IEC 61810-3:2015 specifies special requirements and tests for elementary relays with forcibly guided contacts, also known as mechanically linked contacts. These special requirements apply in addition to the general requirements of IEC 61810-1.

Relais électromécaniques élémentaires - Partie 3: Relais à contacts guidés (liés mécaniquement)

L'IEC 61810-3:2015 spécifie les exigences et essais particuliers pour les relais élémentaires à contacts guidés, également connus sous le nom de contacts liés mécaniquement. Ces exigences particulières s'appliquent en plus des exigences générales de l'IEC 61810-1.

General Information

• Status: Published
• Publication Date: 24-Feb-2015
• ICS: 29.120.70 - Relays
• Technical Committee: TC 94 - Electrical relays
• Current Stage: PPUB - Publication issued
• Start Date: 15-Feb-2015
• Completion Date: 25-Feb-2015

Standards Content (Sample)

IEC 61810-3 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electromechanical elementary relays –
Part 3: Relays with forcibly guided (mechanically linked) contacts

Relais électromécaniques élémentaires –
Partie 3: Relais à contacts guidés (liés mécaniquement)

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IEC 61810-3 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electromechanical elementary relays –

Part 3: Relays with forcibly guided (mechanically linked) contacts

Relais électromécaniques élémentaires –

Partie 3: Relais à contacts guidés (liés mécaniquement)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.70 ISBN 978-2-8322-2236-2

– 2 – IEC 61810-3:2015 © IEC 2015
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions. 6
4 Functional requirements . 7
4.1 Forcibly guided (mechanically linked) operation . 7
4.2 Changeover contacts . 7
4.3 Mechanical endurance. 8
4.4 Electrical endurance . 8
4.5 Operating conditions . 8
4.5.1 Ambient temperature . 8
4.5.2 Energizing quantity . 8
4.6 Characteristic values and marking . 8
4.6.1 Characteristic values . 8
4.6.2 Marking . 8
5 Verification and type tests . 9
5.1 Design verification . 9
5.2 Type tests . 9
5.3 Test procedure . 10
5.3.1 Testing for failure to open . 10
5.3.2 Mechanical and electrical endurance . 10
Bibliography . 11

Figure 1 – Symbol for a forcibly guided (mechanically linked) contact set, type A . 8
Figure 2 – Symbols for use on type B relays . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 3: Relays with forcibly guided (mechanically linked) contacts

FOREWORD
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International Standard IEC 61810-3 has been prepared by IEC technical committee 94: All-or-
nothing electrical relays.
The content of this standard was already published in EN 50205:2002. The revisions in this
standard only involve editorial changes and update of references.
The text of this standard is based on the following documents:
FDIS Report on voting
94/378/FDIS 94/382/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.

– 4 – IEC 61810-3:2015 © IEC 2015
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of 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 publication will remain unchanged until the
stability date indicated on the IEC website 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.
INTRODUCTION
This Standard applies to elementary relays in which special design and constructional
measures are used to ensure that make (normally-open) contacts cannot assume the same
state as break (normally-closed) contacts. These relays can be used in self-monitoring control
systems, e.g. safety-related control systems.

– 6 – IEC 61810-3:2015 © IEC 2015
ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 3: Relays with forcibly guided (mechanically linked) contacts

1 Scope
This part of IEC 61810 specifies special requirements and tests for elementary relays with
forcibly guided contacts, also known as mechanically linked contacts. These special
requirements apply in addition to the general requirements of IEC 61810-1.
NOTE 1 This standard does not apply to electromechanical control circuit devices as described in IEC 60947-5-1.
NOTE 2 IEC 61810-2-1 provides guidelines for the assignment of reliability values.
NOTE 3 Contacts that are not mechanically linked (forcibly guided) are not considered in this standard.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
IEC 60947-5-1, Low-voltage switchgear and controlgear – Part 5-1: Control circuit devices and
switching elements – Electromechanical control circuit devices
IEC 61810-1:2015, Electromechanical elementary relays – Part 1: General and safety
requirements
IEC 61810-7, Electromechanical elementary relays – Part 7: Test and measurement
procedures
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
elementary relay
non-specified time all-or-nothing relay
Note 1 to entry: In this document the word “elementary” is sometimes omitted for clarity.
[SOURCE: IEC 60050-444:2002, 444-01-03, modified – modification of the definition]
3.2
failure to open
fault condition when a contact does not open when expected to do so
3.3
failure criteria
specified conditions to judge if a fault or malfunction is a failure

3.4
fault
fault condition
deviation of the existing condition from the expected condition
3.5
failure
termination of the ability of an item to perform a required function as defined in the failure
criteria
3.6
relay with mechanically linked contacts
relay with forcibly guided contacts
elementary relay with at least one make contact and at least one break contact and including
mechanical measures to prevent any make contact(s) and any break contact(s) being in the
closed position simultaneously
3.7
type A
relay in which all contacts are mechanically linked
3.8
type B
relay containing contacts that are mechanically linked to each other as well as contacts that are
not mechanically linked
4 Functional requirements
4.1 Forcibly guided (mechanically linked) operation
The relay shall be designed such that if a make contact is closed, none of the mechanically
linked break contacts can close and that if a break contact is closed, none of the mechanically
linked make contacts can close. These requirements apply throughout the lifetime of the relay
and under reasonably foreseeable failure conditions.
The effects of reasonably foreseeable breakage of and/or wear to parts of the elementary relay
shall not nullify the function of forcibly guided (mechanically linked) operation.
Contact gaps of open contacts shall be greater than 0,5 mm for single break contacts and
0,3 mm each for double break contacts throughout the manufacturer’s specified endurance of
the relay.
Operation of forcibly guided (mechanically linked) contacts means that if any make contact fails
to open when the relay is de-energized, none of the break contacts shall close. If any break
contact fails to open when the relay is energized, no make contact shall close.
4.2 Changeover contacts
Only break contacts and make contacts are covered by this standard; in the case of relays that
include changeover contacts, either the make circuit or the break circuit of a changeover
contact can be considered to meet the requirements of this standard.
Changeover contacts shall be break-before-make. It shall be assured that the forcibly guided
operation is maintained, as described under the fault conditions described in 5.1.
NOTE Special care is taken in the design of the application to ensure that the integrity of the safety-related circuit
is maintained in the event of a failure.

– 8 – IEC 61810-3:2015 © IEC 2015
4.3 Mechanical endurance
Elementary relays containing forcibly guided (mechanically linked) contacts shall have a
mechanical endurance of at least 10 operating cycles.
4.4 Electrical endurance
The electrical endurance shall be as specified by the manufacturer in accordance with
IEC 61810-1.
4.5 Operating conditions
4.5.1 Ambient temperature
Elementary relays with forcibly guided (mechanically linked) contacts shall function correctly
over an ambient temperature range of at least –10 °C to +55 °C.
4.5.2 Energizing quantity
Unless otherwise stated by the manufacturer, elementary relays with forcibly guided
(mechanically linked) contacts shall at least correspond to class ‘2’ in the operative range of
their rated coil voltage (see 5.3.1 of IEC 61810-1:2015).
4.6 Characteristic values and marking
4.6.1 Characteristic values
The manufacturer shall state in his documentation the following:
a) whether the relay is type A or type B. In the case of type B relays, which contacts are
mechanically linked and which contacts are not mechanically linked;
b) the vibration resistance over the frequency range at least from f = 10 Hz to 200 Hz (see
IEC 61810-7);
c) the shock resistance of the relay in accordance with IEC 61810-7;
d) the contact load(s) according to IEC 61810-1:2015, Annex B or the utilization category(ies)
in accordance with IEC 60947-5-1;
NOTE Commonly utilisation categories AC15 and DC13 are applied.
e) the limits of the operative range.
4.6.2 Marking
Relays with forcibly guided (mechanically linked) contacts shall be marked to indicate whether
they are type A or type B. If a contact schematic is marked on the relay then the following
marking shall be placed adjacent to the schematic.
Type A relays with forcibly guided (mechanically linked) contacts shall be marked either with
the words “type A” or with the symbol given in the Figure 1 below:

Figure 1 – Symbol for a forcibly guided (mechanically linked) contact set, type A

Type B relays with forcibly guided (mechanically linked) contacts shall be marked either with
the words “type B” or with the symbols given in the Figure 2 (Source ISO 7000:2014/Figure
0434) below:
or
Figure 2 – Symbols for use on type B relays
5 Verification and type tests
5.1 Design verification
A failure mode and effect analysis shall be performed considering all parts that are involved in
the forcibly guided (mechanically linked) operation. The analysis shall consider the breakage
and wear of these parts as well as failure to open.
All reasonably foreseeable single faults shall be assumed and their effects considered. If the
fault of a part leads directly to a second fault then the two faults shall be considered. If the fault
of a part is excluded as a failure criteria, the manufacturer shall justify the exclusion, for
example by design calculations or measurements showing over-dimensioning. The failure
criteria “spring broken” shall not be excluded.
It shall be considered whether, in case any electrically conductive parts break or come loose,
the construction of the elementary relay prevents any short-circuits or conductive connections
from occurring which would nullify the function of forcibly guided (mechanically linked)
operation.
NOTE 1 Bridging by conductive parts can be prevented by such means as, for example, insulation or other
appropriate methods applied between the conducting parts.
NOTE 2 Examples of conductive parts are contacts, contact springs and return springs.
The failure of movable functional parts as a result of, for example, breakage or wear shall be
considered and the result expected shall be evaluated.
NOTE 3 An example of a movable functional part is the actuator of the contact set.
5.2 Type tests
Type tests shall be performed to verify the function of forcibly guided (mechanically linked)
operation.
The tests shall be performed on new relays and also on relays that have been subjected to the
electrical and mechanical endurance tests.
The test shall be conducted by simulating the welding of a contact of the elementary relay. The
simulated welding shall be performed under worst case conditions using a separate sample for
each make contact and each break contact. A separate sample shall be used for each
simulated contact welding unless it can be demonstrated by analysis that a reduced number of
samples will give an equivalent test result.
Welding of the contacts shall be simulated by such means as, for example, soldering the
contacts together or using an appropriate glue. The thickness of the contact tips shall not
change by more than 0,02 mm as a result of having been soldered or glued. Break contacts

– 10 – IEC 61810-3:2015 © IEC 2015
shall be soldered or glued with the relay in the release condition. Make contacts shall be
soldered or glued with the relay energised at the lower limit of the operative range.
The defect shall be built into break contacts with the elementary relay in the release condition.
The defect shall be built into make contacts at the lower limit of the operative range of the coil
voltage.
5.3 Test procedure
5.3.1 Testing for failure to open
5.3.1.1 Verification of the contact gap
The tests shall be performed at an ambient temperature of (23 ± 5) °C.
Either of the following methods may be used to verify the contact gap. The manufacturer shall
state in his documentation which method is used:
a) an optical check to determine if the contact gap is ≥ 0,5 mm in the case of single break
contacts, ≥ 0,3
...