prEN IEC 60079-42:2024

SLOVENSKI STANDARD
01-november-2024
Eksplozivne atmosfere - 42. del: Električne varnostne naprave za nadzor
potencialnih virov vžiga ex- opreme
Explosive atmospheres - Part 42: Electrical safety devices for the control of potential
ignition sources for ex-equipment
Atmosphères explosive - Partie 42: Dispositifs électriques de sécurité pour la commande
des sources potentielles d’inflammation des appareils ex
Ta slovenski standard je istoveten z: prEN IEC 60079-42:2024
ICS:
29.260.20 Električni aparati za Electrical apparatus for
eksplozivna ozračja explosive atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

31/1797/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60079-42 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2024-09-27 2024-12-20
SUPERSEDES DOCUMENTS:
31/1706/CD, 31/1735A/CC
IEC TC 31 : EQUIPMENT FOR EXPLOSIVE ATMOSPHERES
SECRETARIAT: SECRETARY:
United Kingdom Mr Tom Stack
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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(SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Explosive atmospheres - Part 42: Electrical safety devices for the control of potential ignition sources for
Ex-Equipment
PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions. You
may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without permis sion in
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31/1797/CDV – 2 – IEC CDV 60079-42 © IEC 2024
1 CONTENTS
2 FOREWORD . 4
3 INTRODUCTION . 6
4 1 Scope . 7
5 2 Normative references . 8
6 3 Terms and definitions . 8
7 4 Basic requirements . 9
8 5 Ignition prevention by safety devices . 9
9 5.1 General concept of ignition risk reduction . 9
10 5.2 Safety characteristics of a safety function . 10
11 5.3 Associated safety device . 10
12 6 Functional requirements for a safety device . 11
13 6.1 General requirements . 11
14 6.2 Specification of the safety function . 11
15 6.3 Requirements for achieving the safety integrity . 11
16 6.3.1 Simple safety devices . 11
17 6.3.2 Complex safety device . 11
18 7 Testing and verification. 12
19 7.1 Type tests . 12
20 7.2 Proof tests . 12
21 8 Marking . 12
22 8.1 General . 12
23 8.2 Electrical safety device controlling an electrical ExEUC, integral to the
24 ExEUC . 12
25 8.3 ExEUC with another associated Type of Protection, integral to the ExEUC . 12
26 8.4 Associated electrical safety device controlling an electrical ExEUC, located
27 outside the ExEUC . 13
28 9 Instructions . 13
29 Annex A (informative) Guidance for assessment of a simple safety device . 14
30 Annex B (informative) Examples for the application of safety devices . 15
31 B.1 General . 15
32 B.2 Ex Equipment with a residual ignition source caused by high temperatures of
33 a brake . 15
34 B.2.1 Problem . 15
35 B.2.2 Ignition Hazard Assessment . 15
36 B.2.3 Safety controls to prevent ignition . 15
37 B.3 Risk reduction by control of the surface temperature . 15
38 B.3.1 Problem . 15
39 B.3.2 Ignition Hazard Assessment . 16
40 B.3.3 Safety controls to prevent ignition . 16
41 B.4 Control of high temperatures . 16
42 B.4.1 Problem . 16
43 B.4.2 Ignition hazard assessment . 16
44 B.4.3 Safety controls. 17
45 Annex C (informative) Use of the Safe Motor Temperature (SMT) sub-function with
46 converter-fed motors . 18
47 C.1 General . 18

IEC CDV 60079-42 © IEC 2024 – 3 – 31/1797/CDV
48 C.2 Reliability of the safety motor temperature control function. . 19
49 C.3 Control without temperature sensors . 19
50 C.4 Control with temperature sensors . 20
51 Bibliography . 21
53 Figure B.1 – Safety device to limit the temperature rise . 16
54 Figure C.1 – Overview . 18
55 Figure C.2 – Control without temperature sensors . 19
56 Figure C.3 – Control with temperature sensors . 20
58 Table 1 – Minimum RRF for a safety function for ignition risk reduction . 10
59 Table C.1 – SMT safety sub function Risk Reduction Factors (RRF) . 19
31/1797/CDV – 4 – IEC CDV 60079-42 © IEC 2024
64 INTERNATIONAL ELECTROTECHNICAL COMMISSION
65 ____________
67 EXPLOSIVE ATMOSPHERES
69 Part 42: Electrical safety devices for the control of potential ignition
70 sources from Ex Equipment, Type of Protection "f"
72 FOREWORD
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105 International Technical Specification IEC 60079-42 has been prepared by IEC technical
106 committee 31: Equipment for explosive atmospheres.
107 Users of this document are advised that interpretation sheets clarifying the interpretation of this
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110 The text of this Technical Specification is based on the following documents:
FDIS Report on voting
31/1418/DTS 31/1441/RVDTS
111 Full information on the voting for the approval of this Technical Specification can be found in
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IEC CDV 60079-42 © IEC 2024 – 5 – 31/1797/CDV
114 The committee has decided that the contents of this publication will remain unchanged until the
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121 This International Technical Specification
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