IEC 60947-5-8:2020
(Main)Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches
Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches
IEC 60947-5-8:2020 specifies requirements for three-position enabling switches. These switches are used as components of enabling devices to provide signals that,
- when activated, allow machine operation to be initiated by a separate start control, and
- when de-activated,
-- initiate a stop function, and
-- prevent initiation of machine operation.
This second edition cancels and replaces the first edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- due to the increasing range of useful applications of three-position enabling switches, note of scope, operational characteristics and tests are reviewed;
- figures for example of devices incorporating enabling switch are added in Annex A;
- new Annex B for procedure to determine reliability data for the switch used in functional safety applications is added.
Appareillage à basse tension - Partie 5-8: Appareils et éléments de commutation pour circuit de commande - Interrupteurs de commande de validation à trois positions
L'IEC 60947-5-8:2020 spécifie les exigences pour les interrupteurs de commande de validation à trois positions. Ces interrupteurs sont utilisés comme composants dans les appareils de commande de validation pour fournir des signaux qui:
- lorsqu’ils sont activés, permettent la mise en marche de la machine par une commande séparée de démarrage; et
- lorsqu’ils sont désactivés:
-- initient une fonction d’arrêt; et
-- évitent la mise en marche de la machine.
Cette deuxième édition annule et remplace la première édition parue en 2006. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- en raison du nombre croissant d’applications utiles possibles avec les interrupteurs de commande de validation à trois positions, le domaine d’application, les caractéristiques de fonctionnement et les essais sont revus;
- des figures représentant des exemples d’appareils incorporant un interrupteur de commande de validation sont ajoutées dans l’Annexe A;
- une nouvelle Annexe B est ajoutée, incluant une procédure visant à déterminer des données de fiabilité pour l’interrupteur utilisé dans des applications de sécurité fonctionnelle.
General Information
Relations
Standards Content (Sample)
IEC 60947-5-8 ®
Edition 2.0 2020-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC 60947-5-8 ®
Edition 2.0 2020-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-8773-6
– 2 – IEC 60947-5-8:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 3
1 General .
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classification . 7
5 Characteristics . 7
6 Product information . 8
7 Normal service, mounting and transport conditions . 10
8 Constructional and performance requirements . 10
9 Tests . 16
Annex A (informative) Example of an enabling devices incorporating
a three-position enabling switch . 23
Annex B (normative) Procedure to determine reliability data for three-position enabling
switches used in functional safety applications . 26
Bibliography . 27
Figure 1 – Operation of three-position enabling switches . 13
Figure 2 – Operating force, travel and enabling contact status . 15
Figure A.1 – Grip type enabling device . 23
Figure A.2 – One hand teaching pendant type enabling device . 23
Figure A.3 – Two hand teaching pendant type enabling device . 24
Figure A.4 – Manual pulse generator . 24
Figure A.5 – Grip type enabling device for hand-held machine . 24
Figure A.6 – Foot actuated enabling device . 25
Figure A.7 – Hoist controller . 25
Figure A.8 – Joystick type enabling device . 25
Table 1 – Force values for F . 15
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches
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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
– 4 – IEC 60947-5-8:2020 RLV © IEC 2020
International Standard IEC 60947-5-8 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) due to the increasing range of useful applications of three-position enabling switches, note
of scope, operational characteristics and tests are reviewed;
b) figures for example of devices incorporating enabling switch are added in Annex A;
c) new Annex B for procedure to determine reliability data for the switch used in functional
safety applications is added.
The text of this document is based on the following documents:
FDIS Report on voting
121A/358/FDIS 121A/369/RVD
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document should be used in conjunction with IEC 60947-1:2020 and
IEC 60947-5-1:2016.
The provisions of the general rules, IEC 60947-1, are applicable to this standard, where
specifically called for. General rules clauses and subclauses thus applicable, as well as tables,
figures and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or
Annex A of IEC 60947-1:2020.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, under the general title Low-voltage switchgear and
controlgear, 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches
1 General
1 Scope
This part of IEC 60947 series specifies requirements for three-position enabling switches.
These switches are used as components of enabling devices described in 10.9 of
IEC 60204-1 to provide signals that,
a) when activated, allow machine operation to be initiated by a separate start control, and
b) when de-activated,
– initiate a stop function, and
– prevent initiation of machine operation.
NOTE 1 The enabling control function is described in 9.2.6.3 9.2.3.9 of IEC 60204-1:2016 but the application of
three-position enabling switches is not limited to a component of the enabling device described in IEC 60204-1.
NOTE 2 This document does not deal with enabling devices.
These switches are intended to be connected to circuits which rated voltage does not exceed
250 V AC 50 Hz/60 Hz or 300 V DC.
EXAMPLE Devices incorporating three-position enabling switches are:
– push-button enabling devices;
– grip actuated enabling devices;
– foot actuated enabling devices.
See Annex A for more typical examples.
This document does not apply to:
– three-position enabling switches for non-electrical control circuits, for example hydraulic,
pneumatic;
– enabling switches without three-position mechanism;
– emergency stop devices (see IEC 60947-5-5).
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 60068-2-1:19902007, Environmental testing – Part 2-1: Tests – Test A: Cold
Amendment 1 (1993)
Amendment 2 (1994)
– 6 – IEC 60947-5-8:2020 RLV © IEC 2020
IEC 60068-2-2:19742007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
Amendment 1 (1993)
Amendment 2 (1994)
IEC 60068-2-6:19952007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration
(sinusoidal)
IEC 60068-2-27:19872008, Environmental testing – Part 2-27: Tests – Test Ea and guidance:
Shock
IEC 60204-1:2005, Safety of machinery – Electrical equipment of machines – Part 1: General
requirements
IEC 60947-1:20042020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-5-1:20032016, Low-voltage switchgear and controlgear – Part 5-1: Control circuit
devices and switching elements – Electromechanical control circuit devices
3 Terms and definitions
For the purposes of this document, the relevant definitions given in Clause 2 of IEC 60947-1
and Clause 2 of IEC 60947-5-1 apply, with the following additional definitions the terms and
definitions given in Clause 3 of IEC 60947-1:2020 and Clause 2 of IEC 60947-5-1:2016, 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
Alphabetical index of definitions
................................................................................................. Reference
A
Actuating system (of a three-position enabling switch) . 3.3
Actuator (of a three-position enabling switch) . 3.4
Auxiliary contact . 3.5
E
Enabling contact . 3.6
Enabling device . 3.1
T
Three-position enabling switch . 3.2
3.1
enabling device
manually operated control device used in conjunction with a start control and which, when
continuously actuated, allows a machine operation
3.2
three-position enabling switch
switch having three sequential actuator positions, in which the contacts are closed when the
actuator is in the mid position (partly depressed) and are open when the actuator is in the rest
(not pressed) position and in the fully depressed position
three-position switch having enabling contact(s)
3.3
actuating system
all the mechanical parts which transmit the actuating force to
the contact elements
[SOURCE: IEC 60050-441:2000, 441-15-21, modified – "all the operating means of a control
switch" replaced by "all the mechanical parts", note to entry deleted.]
3.4
actuator
part of the actuating system which is actuated by a part of
the human body
EXAMPLE A button.
3.5
auxiliary contact
contact of a three-position enabling switch that provides an auxiliary function
Note 1 to entry: Auxiliary contacts may can be normally open and/or normally closed.
3.6
enabling contact
contact of a three-position enabling switch, which is closed when the actuator is in the mid
position (partly depressed, position 2 in Figure 1) and is open when the actuator is in the rest
position (not pressed, position 1 in Figure 1) and in the fully depressed position (position 3 in
Figure 1)
4 Classification
4.1 Contact elements
Subclause 3.1 of IEC 60947-5-1:2016 applies.
4.2 Three-position enabling switch
Three-position enabling switches may be classified according to the contact element and the
nature of the actuating system, e.g. three-position enabling switches, form B.
5 Characteristics
5.1 Summary of characteristics
5.1.1 General
Subclause 4.1.1 of IEC 60947-5-1:2016 applies except for following type of equipment (see
5.2).
5.1.2 Operation of a control an enabling switch
Subclause 4.1.1 4.1.2 of IEC 60947-5-1:2016 applies.
– 8 – IEC 60947-5-8:2020 RLV © IEC 2020
4.1.1.1 Normal conditions of use
Subclause 4.1.1.1 of IEC 60947-5-1 applies.
4.1.1.2 Abnormal conditions of use
Subclause 4.1.1.2 of IEC 60947-5-1 applies.
5.2 Type of three-position enabling switch
4.2.1 Examples of devices incorporating three-position enabling switches
− push-button enabling devices;
− grip actuated enabling devices;
− foot actuated enabling devices; etc.
5.2.1 Number of poles
The number of poles shall be stated by the manufacturer.
5.2.2 Kind of current
Alternating current or direct current.
5.3 Rated and limiting values for switching elements
Subclause 4.3 of IEC 60947-5-1:2016 applies.
5.4 Utilization categories for switching elements
Subclause 4.4 of IEC 60947-5-1:2016 applies.
5.5 Vacant
5.6 Vacant
5.7 Vacant
5.8 Vacant
5.9 Switching overvoltages Vacant
Subclause 4.9 of IEC 60947-1 applies.
5.10 Electrically separated contact elements
Subclause 4.10 of IEC 60947-5-1:2016 applies.
6 Product information
6.1 Nature of information
The following information shall be given by the manufacturer:
Identification
a) The manufacturer's name or trade mark.
b) A type designation or serial number that makes it possible to get the relevant information
concerning the switching element (or the entire control switch) from the manufacturer.
c) “IEC 60947-5-8” if the manufacturer claims compliance with this document.
d) Three-position enabling switches shall be indelibly and legibly marked by the following
symbol:
NOTE If it is not possible to affix the marking to the switch due to size constraints, then the symbol may can be
put in the instructions for installation, operation and maintenance.
Basic rated values and utilization
e) Actuating forces and operational stroke travel of the actuator.
f) Rated operational voltage(s) (see 4.3.1.1 4.3.2.2 of IEC 60947-5-1:2016).
g) Utilization category and rated operational currents at the rated operational voltages of the
switching element.
h) Rated insulation voltage (see 4.3.1.2 4.3.2.3 of IEC 60947-5-1:2016).
i) Rated impulse withstand voltage U in accordance with 4.3.1.3 5.3.1.3 of IEC 60947-
imp
1:2020.
j) IP code (see 5.1 and Annex C of IEC 60947-1:2020).
k) Pollution degree (see 6.1.3.2 of IEC 60947-5-1:2016).
l) Type and maximum ratings of short-circuit protective device (see 8.3.4.3 of
IEC 60947-5-1:2016).
m) Conditional short-circuit current if less than 1 000 A.
n) Indication of contact elements of same polarity.
o) Mechanical and/or electrical durability.
6.2 Marking
6.2.1 General
Marking of data specified in items a), b), c) and d) of 5.1 6.1 is mandatory on the nameplate
of the three-position enabling switch in order to permit the complete information to be
obtained from the manufacturer.
Marking shall be indelible and easily legible, and shall not be placed on screws and easily
removable parts.
Whenever space permits, data under items e) to o) of 5.1 6.1 shall be included on the
nameplate, or on the three-position enabling switch or otherwise in the manufacturer's
published literature.
6.2.2 Terminal identification and marking
Subclause 7.1.7.4 5.2.2 of IEC 60947-5-1:2016 applies.
6.2.3 Functional markings
To avoid confusion with emergency stop devices, the actuator of an enabling switch shall not
be coloured red (see also IEC 60204-1).
– 10 – IEC 60947-5-8:2020 RLV © IEC 2020
6.3 Instructions for installation, operation and maintenance
Subclause 5.3 6.3 of IEC 60947-1:2020 applies with the following additions.
Manufacturers are encouraged to use graphical symbols as set out in international standards.
Examples include ISO 7000 and IEC 60417.
EXAMPLE Following symbols can be used for “skilled person”.
IEC 60417-6182 (2013-09) IEC 60417-6183 (2013-09)
Installation, electrotechnical expertise Installation, mechanical expertise
6.4 Additional information
Subclause 5.4 of IEC 60947-5-1:2016 applies.
7 Normal service, mounting and transport conditions
7.1 General
Clause 6 7 of IEC 60947-1:2020 applies with the following additions.
7.1.3.2 Pollution degree
Unless otherwise stated by the manufacturer, a three-position enabling switch is intended for
installation under environmental conditions of pollution degree 3. However, other pollution
degrees may apply, depending upon the micro-environment.
An enabling switch is intended for installation under environmental conditions of pollution
degree 3. If it can be demonstrated that the micro-environment of a device to which the
enabling switch (or part of) is exposed is different to pollution degree 3, then the pollution
degree of the enabling switch can be adapted.
7.3 Mounting
Means shall be provided to allow the three-position enabling switch to be securely installed in
its intended mounting position.
7.4 Special application
Environmental conditions (e.g. moisture, corrosive atmosphere, UV radiation) may cause
additional requirements.
8 Constructional and performance requirements
8.1 Constructional requirements
8.1.1 General
Subclause 7.1 8.1.1 of IEC 60947-1:2020 applies except for 7.1.1, 7.1.2, 7.1.6, 7.1.8 and
7.1.12, and with the following additions.
7.1.1 Materials
Subclause 7.1.1 of IEC 60947-5-1 applies.
7.1.2 Current-carrying parts and their connections
Subclause 7.1.2 of IEC 60947-5-1 applies.
7.1.3 Clearances and creepage distances
Subclause 7.1.3 of IEC 60947-5-1 applies.
8.1.2 Materials
8.1.2.1 General material requirements
Subclause 7.1.2.1 of IEC 60947-5-1:2016 applies.
8.1.2.2 Glow-wire testing
Subclause 7.1.2.2 of IEC 60947-5-1:2016 applies.
8.1.2.3 Test based on flammability category
Subclause 7.1.2.3 of IEC 60947-5-1:2016 applies.
8.1.2.4 Biological and chemical effects
Under agreement between manufacturer and user, the manufacturer may provide a list of
relevant materials in order to let the user verify that the product is suitable for the application.
NOTE 1 Additional requirements can be relevant in conjunction with special applications/branches e.g. for food
and beverage, chemical industry, marine.
NOTE 2 Three-position enabling switches can be utilized in applications where a human operator can be in
contact with the device for substantial periods, with bare hands. Due consideration can be given to the biological
and chemical effects of skin contact with materials that emit substances when touched, for example, polycyclic
aromatic hydrocarbons (PAH).
8.1.3 Current-carrying parts and their connections
Subclause 7.1.3 of IEC 60947-5-1:2016 applies.
8.1.4 Clearances and creepage distances
Subclause 8.1.4 of IEC 60947-1:2020 applies.
8.1.5 Actuator
8.1.5.1 Insulation
Subclause 8.1.5.1 of IEC 60947-1:2020 applies.
– 12 – IEC 60947-5-8:2020 RLV © IEC 2020
8.1.5.2 Direction of movement
Subclause 8.1.5.2 of IEC 60947-1:2020 applies.
8.1.5.3 Actuating force (or moment torque)
The force (or moment torque) required to operate the actuator shall be compatible with the
intended application, taking into account the size of the actuator, the type of enclosure or
panel, the environment of the installation and the use for which it is intended.
See 8.1.17 for the actuating force on each operation.
8.1.6 Indication of the contact position
Subclause 8.1.6 of IEC 60947-1:2020 applies.
8.1.7 Vacant
8.1.8 Terminals
Subclause 8.1.8 of IEC 60947-1:2020 applies.
8.1.9 Vacant
8.1.10 Provisions for protective earthing
Subclause 8.1.10 of IEC 60947-1:2020 applies.
8.1.11 Enclosures for equipment
Subclause 8.1.11 of IEC 60947-1:2020 applies.
8.1.12 Degrees of protection of enclosed equipment
Subclause 8.1.12 of IEC 60947-1:2020 applies.
8.1.13 Vacant
8.1.14 Class II three-position enabling switches
Subclause 7.1.7 7.1.14 of IEC 60947-5-1:2016 applies.
8.1.15 Requirements for three-position enabling switches with integrally connected
cables
Subclause 7.1.8 7.1.15 of IEC 60947-5-1:2016 applies.
8.1.16 Three-position operation
The three positions are designated as follows (see Figure 2):
− position 1: OFF state of the contact (actuator is not pressed);
− position 2: ON state of the contact (actuator is pressed to the normal enabling position);
− position 3: OFF state of the contact (actuator is fully depressed).
The three-position enabling switch pressed to position 2 shall return to position 1 when
released. The three-position enabling switch shall change from position 2 to position 3 when
pressed further. When released from position 3 to position 1, the switching element shall not
close when the actuator passes through position 2.
Figure 1 illustrates the three positions and the corresponding contact states.
Figure 1 – Operation of three-position enabling switches
The operational stroke and force to actuate the three-position enabling switch from position 1
to position 2 and from position 2 to position 3 shall be stated by the manufacturer.
8.1.17 Operational characteristics
The three-position enabling switch shall be designed and manufactured to satisfy the
following operational characteristics.
• To reduce physiological strain during actuation of three-position enabling switches, F
shall be 10 N or smaller the value of F shall be as stated in Table 1 or lower.
Manufacturer shall declare a maximum F value.
• To reduce the possibility of inadvertent shifting of three-position enabling switches to
position 3, F shall be 2 F or greater and F shall be 2 F or greater equal to or greater
3 2 3 1
than 2 times the larger values of F and F .
1 2
• F shall be 150 N or greater (see 8.2.6 9.2.3).
NOTE 1 To prevent inadvertent shifting of the three-position enabling switch to position 1, it is recommended to
set S to smaller than S S ’ can be set smaller than S .
1 1 1 1
’
NOTE 2 To provide operator with tactile sensation of contact shifting, it is recommended to provide operating
force dips ΔF and ΔF can be provided.
1 3
NOTE 3 The torque value is not specified in this document because there is no known enabling switch using
torque for actuation.
Figure 2 shows the operational characteristics of the three-position enabling switch when the
switch is pressed.
– 14 – IEC 60947-5-8:2020 RLV © IEC 2020
Position 2
Position 1 Position 3
F
F ≤ 10 N
F ≥ 2F
3 1
F ≥ 2F
3 2
F ≥ 150 N
F 5
F
∆F
∆F
1 3
F
F
S S
1 S S
2 3 4
Travel
Operating force and travel
Press
Position 1 → 2 → 3
ON (Closed)
Release
Position 2 → 1
OFF (Open)
S ′ S
1 1
Release
Position 3 → 1
Contact status
IEC 1902/06
Operating force
Key
F Force to turn on the enabling contacts from position 1 to position 2
F Force to maintain the switch in position 2
F Force to turn off the enabling contacts from position 2 to position 3
F Full stroke force (position 3)
F Maximum rated operating force
ΔF Operating force dip across point S
1 1
ΔF Operating force dip across point S
3 3
S Point where the switch shifts from position 1 to position 2. Enabling contacts turn ON
S ’ Point where the switch returns from position 2 to position 1. Enabling contacts turn OFF
S Point where the switch is maintained in position 2
S Point where the switch shifts from position 2 to position 3. Enabling contacts turn OFF
S Full stroke point
Figure 2 – Operating force, travel and enabling contact status
When released from position 3 to position 1, the enabling contacts shall not close.
Table 1 – Force values for F
Designated use of the three-position enabling switch Maximum value of F
N
Actuation of the enabling device by finger 10
Actuation of the enabling device by hand 20
Actuation of the enabling device by foot 25
– 16 – IEC 60947-5-8:2020 RLV © IEC 2020
Manufacturer of foot-actuated enabling devices shall design their device to avoid mechanical
stress to the switch greater than F .
8.2 Performance requirements
8.2.1 General
Subclauses 7.2.1.1 and 7.2.2 of IEC 60947-1 apply with the following additions.
Subclause 8.2.1.1 of IEC 60947-1:2020 applies.
8.2.2 Temperature-rise
Subclause 8.2.2 of IEC 60947-1:2020 applies.
8.2.3 Dielectric properties
Subclause 7.2.3 of IEC 60947-5-1:2016 applies.
8.2.4 Ability to make and break under normal and abnormal conditions
8.2.4.1 General
Subclause 7.2.4 of IEC 60947-5-1:2016 applies with the following addition.
8.2.4.2 Durability
Three-position enabling switches shall be tested according to 8.3.3.6 9.3.3.6.
8.2.5 Conditional short-circuit current
Subclause 7.2.5 of IEC 60947-5-1:2016 applies.
7.2.6 Switching overvoltage
Subclause 7.2.6 of IEC 60947-1 applies.
8.2.6 Additional requirements for control switches suitable for isolation
Subclause 7.2.7 of IEC 60947-5-1:2016 applies.
8.2.7 Shock and vibration
Shock or vibration shall not cause opening of closed contacts or closing of open contacts. The
tests shall be conducted according to 8.3.5.2 and 8.3.5.3 9.3.5.2 and 9.3.5.3.
9 Tests
9.1 Kinds of test
9.1.1 General
Subclause 8.1.1 9.1.1 of IEC 60947-1:2020 applies.
9.1.2 Type tests
Type tests are intended to verify compliance of the design of the three-position enabling
switches with this document.
They comprise the verification of:
a) temperature-rise (8.3.3.3 9.3.3.3);
b) dielectric properties (8.3.3.4 9.3.3.4);
c) making and breaking capacities of switching elements under normal conditions (8.3.3.5
9.3.3.5);
d) making and breaking capacities of switching elements under abnormal conditions (8.3.3.5
9.3.3.5);
e) performance under conditional short-circuit current (8.3.4 9.3.4);
f) constructional requirements (8.2 9.2);
g) degree of protection of three-position enabling switches, if applicable (8.3.1 9.3.1);
h) durability (8.3.3.6 9.3.3.6);
i) shock and vibration (8.3.5 9.3.5).
9.1.3 Routine tests
Routine tests are the responsibility of the manufacturer and are usually limited to a
mechanical inspection and a verification of the electromechanical operation.
The inspection shall be supplemented by a dielectric test which is carried out according to
8.3.3.4 9.3.3.4 with the following amendments: the required minimum duration of voltage
application is reduced to 1 s and the metal foil and external terminal connections are
unnecessary.
Additional routine tests for the three-position enabling switch may be specified as appropriate.
A sampling plan may be accepted.
9.1.4 Sampling tests
Subclause 8.1.4 9.1.4 of IEC 60947-1:2020 applies.
9.1.5 Special tests
These tests are subject to agreement between manufacturer and user.
The manufacturer of the three-position-enabling device (user of the enabling switch) shall
verify all necessary requirements of the application with the three-position-enabling device.
In cases where it is necessary to verify environmental conditions of damp heat, salt mist,
vibration and shock, the tests shall be conducted according to Annex Q of IEC 60947-1:2020.
During the damp heat test and salt mist test, the enabling switch is assembled to an enabling
device, or to a representative enclosure.
Reliability data for three-position enabling switches intended for use in functional safety
applications shall be made available in accordance with Annex B.
9.2 Compliance with constructional requirements
Subclause 8.2 of IEC 60947-1 applies except for 8.2.5 and 8.2.6.
9.2.1 General
Subclause 9.2 of IEC 60947-1:2020 applies except 9.2.6 and 9.2.7 and with the following
additions.
– 18 – IEC 60947-5-8:2020 RLV © IEC 2020
9.2.2 Verification of operation of three-position enabling switches
The requirements of 7.1.9 8.1.16 are verified by operating the actuator while monitoring the
state of the enabling contacts. The monitoring means shall be capable of detecting a contact
closure longer than 0,2 ms.
Three-position operation shall be verified during test sequence VII of 8.3.1 9.3.1.
9.2.3 Verification of operation of actuator
The actuator shall withstand the maximum rated operating force specified by the manufacturer
(see F as defined in Figure 2) in the direction of normal operation.
This shall be verified during test sequence VII of 9.3.1.
9.3 Performance
9.3.1 Test sequences
The type and sequence of tests to be performed on representative samples are as follows.
• Test sequence I (sample No. 1)
– Test No. 1 – Temperature rise (8.3.3.3 9.3.3.3)
– Test No. 2 – Dielectric properties (8.3.3.4 9.3.3.4)
– Test No. 3 – Mechanical properties of terminals (8.2.4 9.2.5 of IEC 60947-1:2020)
• Test sequence II (sample No. 2)
– Test No. 1 – Making and breaking capacities of switching elements under normal
conditions (8.3.3.5.2 8.3.3.5.3 of IEC 60947-5-1:2016)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence III (sample No. 3)
– Test No. 1 – Making and breaking capacities of switching elements under abnormal
conditions (8.3.3.5.3 8.3.3.5.4 of IEC 60947-5-1:2016)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence IV (sample No. 4)
– Test No. 1 – Performance under conditional short-circuit current (8.3.4 9.3.4)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence V (sample No. 5)
– Test No. 1 – Degree of protection of three-position enabling switches (Annex C of
IEC 60947-1:2020)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence VI (sample No. 6)
– Test No. 1 – Verification of clearances and creepage distances, if applicable (7.1.3
8.1.4)
– Test No. 2 – Measurement of actuation force or moment (7.1.10) (8.2.5) (or torque)
(8.1.17, 9.2.2)
– Test No. 3 – Verification of robustness of actuator (8.3.3.7 9.3.3.7)
• Test sequence VII (sample No. 7)
– Test No. 1 – Verification of operation of three-position enabling switches (9.2.2)
– Test No. 12 – Mechanical durability (8.3.3.6.1 9.3.3.6.2, 9.2.3)
– Test No. 23 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
– Test No. 4 – Verification of operation of three-position enabling switches (9.2.2)
• Test sequence VIII (sample No. 8)
– Test No. 1 – Electrical durability (8.3.3.6.2 9.3.3.6.3)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence IX (sample No. 9)
– Test No. 1 – Shock and vibration (8.3.5 9.3.5)
– Test No. 2 – Dielectric verification (8.3.3.5.5 8.3.3.5.6 item b) of IEC 60947-5-1:2016)
There shall be no failure in any of the above tests.
More than one test sequence or all test sequences may be conducted on one sample at the
request of the manufacturer. However, the tests shall be conducted in the sequence given for
each sample above.
NOTE 1 For class II three-position enabling switches insulated by encapsulation, additional samples are required
used (see Annex F of IEC 60947-5-1:2016).
NOTE 2 For three-position enabling switches with integrally connected cables, see Annex G of IEC 60947-5-
1:2016.
For shock and vibration tests, the test shall be conducted on three samples, see 8.3.5 9.3.5.
9.3.2 General test conditions
9.3.2.1 General requirements
Subclause 8.3.2.1 9.3.2.1 of IEC 60947-1:2020 applies with the following addition.
The tests shall be performed with the actuator operated by a machine complying with the
following:
– the operating machine shall apply the actuating force to the actuator in the direction of its
motion;
– the maximum force exerted on the actuator shall not exceed F (see Figure 2);
– at the moment when the switching operation occurs, the velocity of the part of the
operating machine that contacts the actuator shall be between 0,05 m/s and 0,15 m/s;
– the mechanical connection between the operating machine and the actuator shall not
impede the free motion of the actuator away from it.
9.3.2.2 Test quantities
Subclause 8.3.2.2 9.3.2.2 of IEC 60947-1:2020 applies except for 8.3.2.2.3 9.3.2.2.3.
9.3.2.3 Evaluation of test results
The condition of the three-position enabling switch after each test shall be checked by the
verifications applicable to each test.
A three-position enabling switch is deemed to have met the requirements of this document if it
meets the requirements of each test and/or test sequence as applicable.
9.3.2.4 Test report
Subclause 8.3.2.4 9.3.2.4 of IEC 60947-1:2020 applies.
– 20 – IEC 60947-5-8:2020 RLV © IEC 2020
9.3.3 Performance under no-load, normal load and abnormal load conditions
9.3.3.1 Operation
Subclause 8.3.3.1 9.3.3.1 of IEC 60947-1:2020 applies.
9.3.3.2 Vacant
9.3.3.3 Temperature rise
Subclause 8.3.3.3 of IEC 60947-5-1:2016 applies.
9.3.3.4 Dielectric properties
Subclause 8.3.3.4 of IEC 60947-5-1:2016 applies.
9.3.3.5 Making and breaking capacities
Subclause 8.3.3.5 of IEC 60947-5-1:2016 applies.
9.3.3.6 Durability
9.3.3.6.1 General
The three-position enabling switch shall successfully pass the mechanical and electrical
durability tests described in 8.3.3.6.1 and 8.3.3.6.2 9.3.3.6.2 and 9.3.3.6.3.
Minimum test operations: 100 000 cycles
Recommended test operations: 0,1 – 0,3 – 1 – 3 – 10 – 30 – 100 million operations
9.3.3.6.2 Mechanical durability
The three samples (see 8.1 9.1) shall be subjected to the following test.
The test shall be performed for minimum 50 000 cycles of position 1 → 2 → 1 operation and
minimum 50 000 cycles of position 1 → 2 → 3 → 1 operation. The actuator of a three-position
enabling switch shall be subjected to the forces necessary to achieve the required positions.
The maximum rated operating force specified by the manufacturer (see F as defined in
Figure 2) is applied at position 3.
The movement and actuating forces of the three-position enabling switch shall be consistent
throughout the test. This shall be verified by measurement before and after the tests.
The mechanical durability of the three-position enabling switch is defined as the number of
no-load operating cycles which will be attained by all samples tested without repair or
replacement of any part.
Tests shall be carried out according to C.1.2 of IEC 60947-5-1:2016.
During the test, the enabling contacts shall be checked at each change of state by the
manufacturer at the conditions described below, and there shall be no failure.
Test voltage and current: 24 V DC, 10 mA maximum.
Test method: The agreement of switch position and enabling contact status shall be checked
at every position before shifting to the next position.
The enabling contact status shall be checked at each position. The three-position enabling
switch shall be shifted to the next position only when the agreement of switch position and
contact status has been confirmed. When any disagreement of position and contact status is
found, tests shall be stopped.
Position 1: enabling contacts open
↓
Position 2: enabling contacts closed
↓
Position 3: enabling contacts open
↓
Position 3 – Position 1: enabling contacts open
Failure criteria:
During the tests, there shall be no electrical and/or mechanical failures. Following the tests,
the switching element shall pass the dielectric test of 8.3.3.4 of IEC 60947-5-1:2016 with a
test voltage equal to 2 U with a minimum of 1 000 V.
e
9.3.3.6.3 Electrical durability
The test conditions are those of 8.3.3.6.1 9.3.3.6.2 except that the circuit of the switch is
energized according to the manufacturer’s specified ratings in accordance with 5.1 6.1,
item g).
9.3.3.7 Robustness
The actuator shall withstand a force of 150 % of the maximum rated operating force specified
by the manufacturer (see F as defined in Figure 2), applied three times in the direction of
normal operation in a manner simulating human action.
9.3.4 Performance under conditional short-circuit current
Subclause 8.3.4 of IEC 60947-5-1:2016 applies.
9.3.5 Shock and vibration tests
9.3.5.1 Conditioning procedures
The purpose of the following procedures is to expose the three-position enabling switches to
various environmental conditions in order to verify their functioning after such exposure.
The three three-position enabling switches shall be subjected to the following exposures:
– 96 h at +40 °C in dry atmosphere according to test Ba Bb of IEC 60068-2-2;
– 96 h at +5 °C according to test Aa Ab of IEC 60068-2-1.
Following the environmental exposures and after the samples have been restored to room
temperature, the sequence
...
IEC 60947-5-8 ®
Edition 2.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
Appareillage à basse tension –
Partie 5-8: Appareils et éléments de commutation pour circuits de commande –
Interrupteurs de commande de validation à trois positions
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.
A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.
Recherche de publications IEC - Electropedia - www.electropedia.org
webstore.iec.ch/advsearchform Le premier dictionnaire d'électrotechnologie en ligne au
La recherche avancée permet de trouver des publications IEC monde, avec plus de 22 000 articles terminologiques en
en utilisant différents critères (numéro de référence, texte, anglais et en français, ainsi que les termes équivalents dans
comité d’études,…). Elle donne aussi des informations sur les 16 langues additionnelles. Egalement appelé Vocabulaire
projets et les publications remplacées ou retirées. Electrotechnique International (IEV) en ligne.
IEC Just Published - webstore.iec.ch/justpublished Glossaire IEC - std.iec.ch/glossary
Restez informé sur les nouvelles publications IEC. Just 67 000 entrées terminologiques électrotechniques, en anglais
Published détaille les nouvelles publications parues. et en français, extraites des articles Termes et Définitions des
Disponible en ligne et une fois par mois par email. publications IEC parues depuis 2002. Plus certaines entrées
antérieures extraites des publications des CE 37, 77, 86 et
Service Clients - webstore.iec.ch/csc CISPR de l'IEC.
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
IEC 60947-5-8 ®
Edition 2.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
Appareillage à basse tension –
Partie 5-8: Appareils et éléments de commutation pour circuits de commande –
Interrupteurs de commande de validation à trois positions
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-8606-7
– 2 – IEC 60947-5-8:2020 © IEC 2020
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classification . 7
5 Characteristics . 7
6 Product information . 8
7 Normal service, mounting and transport conditions . 9
8 Constructional and performance requirements . 10
9 Tests . 14
Annex A (informative) Example of enabling devices incorporating a three-position
enabling switch . 21
Annex B (normative) Procedure to determine reliability data for three-position enabling
switches used in functional safety applications . 24
Bibliography . 25
Figure 1 – Operation of three-position enabling switches . 12
Figure 2 – Operating force, travel and enabling contact status . 13
Figure A.1 – Grip type enabling device . 21
Figure A.2 – One hand teaching pendant type enabling device . 21
Figure A.3 – Two hand teaching pendant type enabling device . 22
Figure A.4 – Manual pulse generator . 22
Figure A.5 – Grip type enabling device for hand-held machine . 22
Figure A.6 – Foot actuated enabling device . 23
Figure A.7 – Hoist controller . 23
Figure A.8 – Joystick type enabling device . 23
Table 1 – Force values for F . 13
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches
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 60947-5-8 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) due to the increasing range of useful applications of three-position enabling switches, note
of scope, operational characteristics and tests are reviewed;
b) figures for example of devices incorporating enabling switch are added in Annex A;
c) new Annex B for procedure to determine reliability data for the switch used in functional
safety applications is added.
– 4 – IEC 60947-5-8:2020 © IEC 2020
The text of this document is based on the following documents:
FDIS Report on voting
121A/358/FDIS 121A/369/RVD
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document should be used in conjunction with IEC 60947-1:2020 and
IEC 60947-5-1:2016.
The provisions of the general rules, IEC 60947-1, are applicable to this standard, where
specifically called for. General rules clauses and subclauses thus applicable, as well as tables,
figures and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or
Annex A of IEC 60947-1:2020.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, under the general title Low-voltage switchgear and
controlgear, 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches
1 Scope
This part of IEC 60947 series specifies requirements for three-position enabling switches.
These switches are used as components of enabling devices to provide signals that,
a) when activated, allow machine operation to be initiated by a separate start control, and
b) when de-activated,
– initiate a stop function, and
– prevent initiation of machine operation.
NOTE 1 The enabling control function is described in 9.2.3.9 of IEC 60204-1:2016 but the application of three-
position enabling switches is not limited to a component of the enabling device described in IEC 60204-1.
NOTE 2 This document does not deal with enabling devices.
These switches are intended to be connected to circuits which rated voltage does not exceed
250 V AC 50 Hz/60 Hz or 300 V DC.
EXAMPLE Devices incorporating three-position enabling switches are:
– push-button enabling devices;
– grip actuated enabling devices;
– foot actuated enabling devices.
See Annex A for more typical examples.
This document does not apply to:
– three-position enabling switches for non-electrical control circuits, for example hydraulic,
pneumatic;
– enabling switches without three-position mechanism;
– emergency stop devices (see IEC 60947-5-5).
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 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-6:2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests – Test Ea and guidance:
Shock
– 6 – IEC 60947-5-8:2020 © IEC 2020
IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-5-1:2016, Low-voltage switchgear and controlgear – Part 5-1: Control circuit
devices and switching elements – Electromechanical control circuit devices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in Clause 3 of IEC 60947-
1:2020 and Clause 2 of IEC 60947-5-1:2016, 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
Alphabetical index of definitions
Reference
A
Actuating system . 3.3
Actuator . 3.4
Auxiliary contact . 3.5
E
Enabling contact . 3.6
Enabling device . 3.1
T
Three-position enabling switch . 3.2
3.1
enabling device
manually operated control device used in conjunction with a start control and which, when
continuously actuated, allows a machine operation
3.2
three-position enabling switch
three-position switch having enabling contact(s)
3.3
actuating system
all the mechanical parts which transmit the actuating force to
the contact elements
[SOURCE: IEC 60050-441:2000, 441-15-21, modified – "all the operating means of a control
switch" replaced by "all the mechanical parts", note to entry deleted.]
3.4
actuator
part of the actuating system which is actuated by a part of
the human body
EXAMPLE A button.
3.5
auxiliary contact
contact of a three-position enabling switch that provides an auxiliary function
Note 1 to entry: Auxiliary contacts can be normally open and/or normally closed.
3.6
enabling contact
contact of a three-position enabling switch, which is closed when the actuator is in the mid
position (partly depressed, position 2 in Figure 1) and is open when the actuator is in the rest
position (not pressed, position 1 in Figure 1) and in the fully depressed position (position 3 in
Figure 1)
4 Classification
4.1 Contact elements
Subclause 3.1 of IEC 60947-5-1:2016 applies.
4.2 Three-position enabling switch
Three-position enabling switches may be classified according to the contact element and the
nature of the actuating system, e.g. three-position enabling switches, form B.
5 Characteristics
5.1 Summary of characteristics
5.1.1 General
Subclause 4.1.1 of IEC 60947-5-1:2016 applies except for following type of equipment (see
5.2).
5.1.2 Operation of an enabling switch
Subclause 4.1.2 of IEC 60947-5-1:2016 applies.
5.2 Type of three-position enabling switch
5.2.1 Number of poles
The number of poles shall be stated by the manufacturer.
5.2.2 Kind of current
Alternating current or direct current.
5.3 Rated and limiting values for switching elements
Subclause 4.3 of IEC 60947-5-1:2016 applies.
5.4 Utilization categories for switching elements
Subclause 4.4 of IEC 60947-5-1:2016 applies.
– 8 – IEC 60947-5-8:2020 © IEC 2020
5.5 Vacant
5.6 Vacant
5.7 Vacant
5.8 Vacant
5.9 Vacant
5.10 Electrically separated contact elements
Subclause 4.10 of IEC 60947-5-1:2016 applies.
6 Product information
6.1 Nature of information
The following information shall be given by the manufacturer:
Identification
a) The manufacturer's name or trade mark.
b) A type designation or serial number that makes it possible to get the relevant information
concerning the switching element (or the entire control switch) from the manufacturer.
c) “IEC 60947-5-8” if the manufacturer claims compliance with this document.
d) Three-position enabling switches shall be indelibly and legibly marked by the following
symbol:
NOTE If it is not possible to affix the marking to the switch due to size constraints, then the symbol can be put in
the instructions for installation, operation and maintenance.
Basic rated values and utilization
e) Actuating forces and travel of the actuator.
f) Rated operational voltage(s) (see 4.3.2.2 of IEC 60947-5-1:2016).
g) Utilization category and rated operational currents at the rated operational voltages of the
switching element.
h) Rated insulation voltage (see 4.3.2.3 of IEC 60947-5-1:2016).
i) Rated impulse withstand voltage U in accordance with 5.3.1.3 of IEC 60947-1:2020.
imp
j) IP code (see Annex C of IEC 60947-1:2020).
k) Pollution degree (see 6.1.3.2 of IEC 60947-5-1:2016).
l) Type and maximum ratings of short-circuit protective device (see 8.3.4.3 of
IEC 60947-5-1:2016).
m) Conditional short-circuit current if less than 1 000 A.
n) Indication of contact elements of same polarity.
o) Mechanical and/or electrical durability.
6.2 Marking
6.2.1 General
Marking of data specified in items a), b), c) and d) of 6.1 is mandatory on the nameplate of
the three-position enabling switch in order to permit the complete information to be obtained
from the manufacturer.
Marking shall be indelible and easily legible, and shall not be placed on screws and easily
removable parts.
Whenever space permits, data under items e) to o) of 6.1 shall be included on the nameplate,
or on the three-position enabling switch or otherwise in the manufacturer's published literature.
6.2.2 Terminal identification and marking
Subclause 5.2.2 of IEC 60947-5-1:2016 applies.
6.2.3 Functional markings
To avoid confusion with emergency stop devices, the actuator of an enabling switch shall not
be coloured red (see IEC 60204-1).
6.3 Instructions for installation, operation and maintenance
Subclause 6.3 of IEC 60947-1:2020 applies with the following additions.
Manufacturers are encouraged to use graphical symbols as set out in international standards.
Examples include ISO 7000 and IEC 60417.
EXAMPLE Following symbols can be used for “skilled person”.
IEC 60417-6182 (2013-09) IEC 60417-6183 (2013-09)
Installation, electrotechnical expertise Installation, mechanical expertise
6.4 Additional information
Subclause 5.4 of IEC 60947-5-1:2016 applies.
7 Normal service, mounting and transport conditions
7.1 General
Clause 7 of IEC 60947-1:2020 applies with the following additions.
– 10 – IEC 60947-5-8:2020 © IEC 2020
7.1.3.2 Pollution degree
An enabling switch is intended for installation under environmental conditions of pollution
degree 3. If it can be demonstrated that the micro-environment of a device to which the
enabling switch (or part of) is exposed is different to pollution degree 3, then the pollution
degree of the enabling switch can be adapted.
7.3 Mounting
Means shall be provided to allow the three-position enabling switch to be securely installed in
its intended mounting position.
7.4 Special application
Environmental conditions (e.g. moisture, corrosive atmosphere, UV radiation) may cause
additional requirements.
8 Constructional and performance requirements
8.1 Constructional requirements
8.1.1 General
Subclause 8.1.1 of IEC 60947-1:2020 applies.
8.1.2 Materials
8.1.2.1 General material requirements
Subclause 7.1.2.1 of IEC 60947-5-1:2016 applies.
8.1.2.2 Glow-wire testing
Subclause 7.1.2.2 of IEC 60947-5-1:2016 applies.
8.1.2.3 Test based on flammability category
Subclause 7.1.2.3 of IEC 60947-5-1:2016 applies.
8.1.2.4 Biological and chemical effects
Under agreement between manufacturer and user, the manufacturer may provide a list of
relevant materials in order to let the user verify that the product is suitable for the application.
NOTE 1 Additional requirements can be relevant in conjunction with special applications/branches e.g. for food
and beverage, chemical industry, marine.
NOTE 2 Three-position enabling switches can be utilized in applications where a human operator can be in
contact with the device for substantial periods, with bare hands. Due consideration can be given to the biological
and chemical effects of skin contact with materials that emit substances when touched, for example, polycyclic
aromatic hydrocarbons (PAH).
8.1.3 Current-carrying parts and their connections
Subclause 7.1.3 of IEC 60947-5-1:2016 applies.
8.1.4 Clearances and creepage distances
Subclause 8.1.4 of IEC 60947-1:2020 applies.
8.1.5 Actuator
8.1.5.1 Insulation
Subclause 8.1.5.1 of IEC 60947-1:2020 applies.
8.1.5.2 Direction of movement
Subclause 8.1.5.2 of IEC 60947-1:2020 applies.
8.1.5.3 Actuating force (or torque)
The force (or torque) required to operate the actuator shall be compatible with the intended
application, taking into account the size of the actuator, the type of enclosure or panel, the
environment of the installation and the use for which it is intended.
See 8.1.17 for the actuating force on each operation.
8.1.6 Indication of the contact position
Subclause 8.1.6 of IEC 60947-1:2020 applies.
8.1.7 Vacant
8.1.8 Terminals
Subclause 8.1.8 of IEC 60947-1:2020 applies.
8.1.9 Vacant
8.1.10 Provisions for protective earthing
Subclause 8.1.10 of IEC 60947-1:2020 applies.
8.1.11 Enclosures for equipment
Subclause 8.1.11 of IEC 60947-1:2020 applies.
8.1.12 Degrees of protection of enclosed equipment
Subclause 8.1.12 of IEC 60947-1:2020 applies.
8.1.13 Vacant
8.1.14 Class II three-position enabling switches
Subclause 7.1.14 of IEC 60947-5-1:2016 applies.
8.1.15 Requirements for three-position enabling switches with integrally connected
cables
Subclause 7.1.15 of IEC 60947-5-1:2016 applies.
8.1.16 Three-position operation
The three positions are designated as follows (see Figure 2):
− position 1: OFF state of the contact (actuator is not pressed);
− position 2: ON state of the contact (actuator is pressed to the normal enabling position);
– 12 – IEC 60947-5-8:2020 © IEC 2020
− position 3: OFF state of the contact (actuator is fully depressed).
The three-position enabling switch pressed to position 2 shall return to position 1 when
released. The three-position enabling switch shall change from position 2 to position 3 when
pressed further. When released from position 3 to position 1, the switching element shall not
close when the actuator passes through position 2.
Figure 1 illustrates the three positions and the corresponding contact states.
Figure 1 – Operation of three-position enabling switches
The operational stroke and force to actuate the three-position enabling switch from position 1
to position 2 and from position 2 to position 3 shall be stated by the manufacturer.
8.1.17 Operational characteristics
The three-position enabling switch shall be designed and manufactured to satisfy the
following operational characteristics.
• To reduce physiological strain during actuation of three-position enabling switches, the
value of F shall be as stated in Table 1 or lower. Manufacturer shall declare a maximum
F value.
• To reduce the possibility of inadvertent shifting of three-position enabling switches to
position 3, F shall be equal to or greater than 2 times the larger values of F and F .
3 1 2
• F shall be 150 N or greater (see 9.2.3).
NOTE 1 To prevent inadvertent shifting of the three-position enabling switch to position 1, S ’ can be set smaller
than S .
NOTE 2 To provide operator with tactile sensation of contact shifting, operating force dips ΔF and ΔF can be
1 3
provided.
NOTE 3 The torque value is not specified in this document because there is no known enabling switch using
torque for actuation.
Figure 2 shows the operational characteristics of the three-position enabling switch when the
switch is pressed.
Key
F Force to turn on the enabling contacts from position 1 to position 2
F Force to maintain the switch in position 2
F Force to turn off the enabling contacts from position 2 to position 3
F Full stroke force (position 3)
F Maximum rated operating force
ΔF Operating force dip across point S
1 1
ΔF Operating force dip across point S
3 3
S Point where the switch shifts from position 1 to position 2. Enabling contacts turn ON
S ’ Point where the switch returns from position 2 to position 1. Enabling contacts turn OFF
S Point where the switch is maintained in position 2
S Point where the switch shifts from position 2 to position 3. Enabling contacts turn OFF
S Full stroke point
Figure 2 – Operating force, travel and enabling contact status
When released from position 3 to position 1, the enabling contacts shall not close.
Table 1 – Force values for F
Designated use of the three-position enabling switch Maximum value of F
N
Actuation of the enabling device by finger 10
Actuation of the enabling device by hand 20
Actuation of the enabling device by foot 25
– 14 – IEC 60947-5-8:2020 © IEC 2020
Manufacturer of foot-actuated enabling devices shall design their device to avoid mechanical
stress to the switch greater than F .
8.2 Performance requirements
8.2.1 General
Subclause 8.2.1.1 of IEC 60947-1:2020 applies.
8.2.2 Temperature-rise
Subclause 8.2.2 of IEC 60947-1:2020 applies.
8.2.3 Dielectric properties
Subclause 7.2.3 of IEC 60947-5-1:2016 applies.
8.2.4 Ability to make and break under normal and abnormal conditions
8.2.4.1 General
Subclause 7.2.4 of IEC 60947-5-1:2016 applies with the following addition.
8.2.4.2 Durability
Three-position enabling switches shall be tested according to 9.3.3.6.
8.2.5 Conditional short-circuit current
Subclause 7.2.5 of IEC 60947-5-1:2016 applies.
8.2.6 Additional requirements for control switches suitable for isolation
Subclause 7.2.7 of IEC 60947-5-1:2016 applies.
8.2.7 Shock and vibration
Shock or vibration shall not cause opening of closed contacts or closing of open contacts. The
tests shall be conducted according to 9.3.5.2 and 9.3.5.3.
9 Tests
9.1 Kinds of test
9.1.1 General
Subclause 9.1.1 of IEC 60947-1:2020 applies.
9.1.2 Type tests
Type tests are intended to verify compliance of the design of the three-position enabling
switches with this document.
They comprise the verification of:
a) temperature-rise (9.3.3.3);
b) dielectric properties (9.3.3.4);
c) making and breaking capacities of switching elements under normal conditions (9.3.3.5);
d) making and breaking capacities of switching elements under abnormal conditions (9.3.3.5);
e) performance under conditional short-circuit current (9.3.4);
f) constructional requirements (9.2);
g) degree of protection of three-position enabling switches, if applicable (9.3.1);
h) durability (9.3.3.6);
i) shock and vibration (9.3.5).
9.1.3 Routine tests
Routine tests are the responsibility of the manufacturer and are usually limited to a
mechanical inspection and a verification of the electromechanical operation.
The inspection shall be supplemented by a dielectric test which is carried out according to
9.3.3.4 with the following amendments: the required minimum duration of voltage application
is reduced to 1 s and the metal foil and external terminal connections are unnecessary.
Additional routine tests for the three-position enabling switch may be specified as appropriate.
A sampling plan may be accepted.
9.1.4 Sampling tests
Subclause 9.1.4 of IEC 60947-1:2020 applies.
9.1.5 Special tests
These tests are subject to agreement between manufacturer and user.
The manufacturer of the three-position-enabling device (user of the enabling switch) shall
verify all necessary requirements of the application with the three-position-enabling device.
In cases where it is necessary to verify environmental conditions of damp heat, salt mist,
vibration and shock, the tests shall be conducted according to Annex Q of IEC 60947-1:2020.
During the damp heat test and salt mist test, the enabling switch is assembled to an enabling
device, or to a representative enclosure.
Reliability data for three-position enabling switches intended for use in functional safety
applications shall be made available in accordance with Annex B.
9.2 Compliance with constructional requirements
9.2.1 General
Subclause 9.2 of IEC 60947-1:2020 applies except 9.2.6 and 9.2.7 and with the following
additions.
9.2.2 Verification of operation of three-position enabling switches
The requirements of 8.1.16 are verified by operating the actuator while monitoring the state of
the enabling contacts. The monitoring means shall be capable of detecting a contact closure
longer than 0,2 ms.
Three-position operation shall be verified during test sequence VII of 9.3.1.
– 16 – IEC 60947-5-8:2020 © IEC 2020
9.2.3 Verification of operation of actuator
The actuator shall withstand the maximum rated operating force specified by the manufacturer
(see F as defined in Figure 2) in the direction of normal operation.
This shall be verified during test sequence VII of 9.3.1.
9.3 Performance
9.3.1 Test sequences
The type and sequence of tests to be performed on representative samples are as follows.
• Test sequence I (sample No. 1)
– Test No. 1 – Temperature rise (9.3.3.3)
– Test No. 2 – Dielectric properties (9.3.3.4)
– Test No. 3 – Mechanical properties of terminals (9.2.5 of IEC 60947-1:2020)
• Test sequence II (sample No. 2)
– Test No. 1 – Making and breaking capacities of switching elements under normal
conditions (8.3.3.5.3 of IEC 60947-5-1:2016)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence III (sample No. 3)
– Test No. 1 – Making and breaking capacities of switching elements under abnormal
conditions (8.3.3.5.4 of IEC 60947-5-1:2016)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence IV (sample No. 4)
– Test No. 1 – Performance under conditional short-circuit current (9.3.4)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence V (sample No. 5)
– Test No. 1 – Degree of protection of three-position enabling switches (Annex C of
IEC 60947-1:2020)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence VI (sample No. 6)
– Test No. 1 – Verification of clearances and creepage distances, if applicable (8.1.4)
– Test No. 2 – Measurement of actuation force (or torque) (8.1.17, 9.2.2)
– Test No. 3 – Verification of robustness of actuator (9.3.3.7)
• Test sequence VII (sample No. 7)
– Test No. 1 – Verification of operation of three-position enabling switches (9.2.2)
– Test No. 2 – Mechanical durability (9.3.3.6.2, 9.2.3)
– Test No. 3 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
– Test No. 4 – Verification of operation of three-position enabling switches (9.2.2)
• Test sequence VIII (sample No. 8)
– Test No. 1 – Electrical durability (9.3.3.6.3)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
• Test sequence IX (sample No. 9)
– Test No. 1 – Shock and vibration (9.3.5)
– Test No. 2 – Dielectric verification (8.3.3.5.6 item b) of IEC 60947-5-1:2016)
There shall be no failure in any of the above tests.
More than one test sequence or all test sequences may be conducted on one sample at the
request of the manufacturer. However, the tests shall be conducted in the sequence given for
each sample above.
NOTE 1 For class II three-position enabling switches insulated by encapsulation, additional samples are used
(see Annex F of IEC 60947-5-1:2016).
NOTE 2 For three-position enabling switches with integrally connected cables, see Annex G of IEC 60947-5-
1:2016.
For shock and vibration tests, the test shall be conducted on three samples, see 9.3.5.
9.3.2 General test conditions
9.3.2.1 General requirements
Subclause 9.3.2.1 of IEC 60947-1:2020 applies with the following addition.
The tests shall be performed with the actuator operated by a machine complying with the
following:
– the operating machine shall apply the actuating force to the actuator in the direction of its
motion;
– the maximum force exerted on the actuator shall not exceed F (see Figure 2);
– at the moment when the switching operation occurs, the velocity of the part of the
operating machine that contacts the actuator shall be between 0,05 m/s and 0,15 m/s;
– the mechanical connection between the operating machine and the actuator shall not
impede the free motion of the actuator away from it.
9.3.2.2 Test quantities
Subclause 9.3.2.2 of IEC 60947-1:2020 applies except for 9.3.2.2.3.
9.3.2.3 Evaluation of test results
The condition of the three-position enabling switch after each test shall be checked by the
verifications applicable to each test.
A three-position enabling switch is deemed to have met the requirements of this document if it
meets the requirements of each test and/or test sequence as applicable.
9.3.2.4 Test report
Subclause 9.3.2.4 of IEC 60947-1:2020 applies.
9.3.3 Performance under no-load, normal load and abnormal load conditions
9.3.3.1 Operation
Subclause 9.3.3.1 of IEC 60947-1:2020 applies.
9.3.3.2 Vacant
9.3.3.3 Temperature rise
Subclause 8.3.3.3 of IEC 60947-5-1:2016 applies.
– 18 – IEC 60947-5-8:2020 © IEC 2020
9.3.3.4 Dielectric properties
Subclause 8.3.3.4 of IEC 60947-5-1:2016 applies.
9.3.3.5 Making and breaking capacities
Subclause 8.3.3.5 of IEC 60947-5-1:2016 applies.
9.3.3.6 Durability
9.3.3.6.1 General
The three-position enabling switch shall successfully pass the mechanical and electrical
durability tests described in 9.3.3.6.2 and 9.3.3.6.3.
Minimum test operations: 100 000 cycles
Recommended test operations: 0,1 – 0,3 – 1 – 3 – 10 – 30 – 100 million operations
9.3.3.6.2 Mechanical durability
The three samples (see 9.1) shall be subjected to the following test.
The test shall be performed for minimum 50 000 cycles of position 1 → 2 → 1 operation and
minimum 50 000 cycles of position 1 → 2 → 3 → 1 operation. The actuator of a three-position
enabling switch shall be subjected to the forces necessary to achieve the required positions.
The maximum rated operating force specified by the manufacturer (see F as defined in
Figure 2) is applied at position 3.
The movement and actuating forces of the three-position enabling switch shall be consistent
throughout the test. This shall be verified by measurement before and after the tests.
The mechanical durability of the three-position enabling switch is defined as the number of
no-load operating cycles which will be attained by all samples tested without repair or
replacement of any part.
Tests shall be carried out according to C.1.2 of IEC 60947-5-1:2016.
During the test, the enabling contacts shall be checked at each change of state by the
manufacturer at the conditions described below, and there shall be no failure.
Test voltage and current: 24 V DC, 10 mA maximum.
Test method: The agreement of switch position and enabling contact status shall be checked
at every position before shifting to the next position.
The enabling contact status shall be checked at each position. The three-position enabling
switch shall be shifted to the next position only when the agreement of switch position and
contact status has been confirmed. When any disagreement of position and contact status is
found, tests shall be stopped.
Position 1: enabling contacts open
↓
Position 2: enabling contacts closed
↓
Position 3: enabling contacts open
↓
Position 3 – Position 1: enabling contacts open
Failure criteria:
During the tests, there shall be no electrical and/or mechanical failures. Following the tests,
the switching element shall pass the dielectric test of 8.3.3.4 of IEC 60947-5-1:2016 with a
test voltage equal to 2 U with a minimum of 1 000 V.
e
9.3.3.6.3 Electrical durability
The test conditions are those of 9.3.3.6.2 except that the circuit of the switch is energized
according to the manufacturer’s specified ratings in accordance with 6.1, item g).
9.3.3.7 Robustness
The actuator shall withstand a force of 150 % of the maximum rated operating force specified
as defined in Figure 2), applied three times in the direction of
by the manufacturer (see F
normal operation in a manner simulating human action.
9.3.4 Performance under conditional short-circuit current
Subclause 8.3.4 of IEC 60947-5-1:2016 applies.
9.3.5 Shock and vibration tests
9.3.5.1 Conditioning procedures
The purpose of the following procedures is to expose the three-position enabling switches to
various environmental conditions in order to verify their functioning after such exposure.
The three three-position enabling switches shall be subjected to the following exposures:
– 96 h at +40 °C in dry atmosphere according to test Bb of IEC 60068-2-2;
– 96 h at +5 °C according to test Ab of IEC 60068-2-1.
Following the environmental exposures and after the samples have been restored to room
temperature, the sequence of tests in 9.3.5.2 and 9.3.5.3 shall be conducted.
9.3.5.2 Shock
The three three-position enabling switches that have been conditioned in accordance with
9.3.5.1 shall be tested in each of the three mutually perpendicular axes.
Each three-position enabling switch is tested in position 1 and shall withstand 15 g shock in
both directions of each axis according to IEC 60068-2-27: 11 ms – 15 g.
During the test, no closed contacts shall open and no open contacts shall close.
The monitoring means shall be able to detect any opening or closing of contacts longer than
0,2 ms.
– 20 – IEC 60947-5-8:2020 © IEC 2020
9.3.5.3 Vibration
The three sample
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...