Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches

IEC 60947-5-8:2020 is available as IEC 60947-5-8:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
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

IEC 60947-5-8:2020 est disponible sous forme de IEC 60947-5-8:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
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

Status
Published
Publication Date
11-Aug-2020
Current Stage
PPUB - Publication issued
Completion Date
12-Aug-2020
Ref Project

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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
IEC 60947-5-8:2020-08(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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

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

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

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

---------------------- Page: 4 ----------------------
IEC 60947-5-8:2020 © IEC 2020 – 3 –
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

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indispensable for the correct application of this publication.

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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 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.
---------------------- Page: 5 ----------------------
– 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.
---------------------- Page: 6 ----------------------
IEC 60947-5-8:2020 © IEC 2020 – 5 –
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
---------------------- Page: 7 ----------------------
– 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

Actuating system ................................................................................................................. 3.3

Actuator ............................................................................................................................... 3.4

Auxiliary contact .................................................................................................................. 3.5

Enabling contact .................................................................................................................. 3.6

Enabling device ................................................................................................................... 3.1

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
---------------------- Page: 8 ----------------------
IEC 60947-5-8:2020 © IEC 2020 – 7 –
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.
---------------------- Page: 9 ----------------------
– 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.
---------------------- Page: 10 ----------------------
IEC 60947-5-8:2020 © IEC 2020 – 9 –
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.
---------------------- Page: 11 ----------------------
– 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.
---------------------- Page: 12 ----------------------
IEC 60947-5-8:2020 © IEC 2020 – 11 –
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);

---------------------- Page: 13 ----------------------
– 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 pr
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