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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
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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
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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)
...