FprEN IEC 60079-25:2020

SLOVENSKI STANDARD
oSIST prEN IEC 60079-25:2019
01-maj-2019
(NVSOR]LYQHDWPRVIHUHGHO/DVWQRYDUQLHOHNWULþQLVLVWHPL
Explosive atmospheres - Part 25: Intrinsically safe electrical systems
Explosionsfähige Atmosphäre - Teil 25: Eigensichere Systeme
Atmosphères explosives - Partie 25: Systèmes électriques de sécurité intrinsèque
Ta slovenski standard je istoveten z: prEN IEC 60079-25:2019
ICS:
29.260.20 (OHNWULþQLDSDUDWL]D Electrical apparatus for
HNVSOR]LYQDR]UDþMD explosive atmospheres
oSIST prEN IEC 60079-25:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

This document is still under study and subject to change. It should not be used for reference purposes.

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download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National

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3 FOREWORD ........................................................................................................................... 4

4 1 Scope .............................................................................................................................. 8

5 2 Normative references ...................................................................................................... 8

6 3 Terms and definitions ...................................................................................................... 8

7 4 Descriptive system document .......................................................................................... 9

8 5 Grouping and temperature classification ........................................................................ 10

9 6 Levels of Protection ....................................................................................................... 10

10 6.1 General ................................................................................................................. 10

11 6.2 Level of Protection “ia” .......................................................................................... 10

12 6.3 Level of Protection “ib” .......................................................................................... 10

13 6.4 Level of Protection “ic” .......................................................................................... 10

14 7 Non-intrinsically safe circuits ......................................................................................... 11

15 8 Interconnecting wiring / cables used in an intrinsically safe system ............................... 11

16 8.1 General ................................................................................................................. 11

17 8.2 Cables containing a single intrinsically safe circuit ................................................ 11

18 8.3 Cables containing more than one intrinsically safe circuit ...................................... 11

19 9 Requirements of single and multi-circuit cables ............................................................. 11

20 9.1 General ................................................................................................................. 11

21 9.2 Dielectric strength ................................................................................................. 12

22 9.2.1 Cables containing a single intrinsically safe circuit ......................................... 12

23 9.2.2 Cables containing more than one intrinsically safe circuit .............................. 12

24 9.3 Intrinsic safety parameters of cables ..................................................................... 12

25 9.4 Conducting screens .............................................................................................. 12

26 9.5 Types of multi-circuit cables .................................................................................. 12

27 9.5.1 General ......................................................................................................... 12

28 9.5.2 Type A cable ................................................................................................. 12

29 9.5.3 Type B cable ................................................................................................. 13

30 9.5.4 Type C cable ................................................................................................. 13

31 10 Enclosures .................................................................................................................... 13

32 11 Earthing and bonding of intrinsically safe systems ......................................................... 13

33 12 Assessment of an intrinsically safe system .................................................................... 13

34 12.1 General ................................................................................................................. 13

35 12.2 Systems containing only apparatus certified to IEC 60079-11 ............................... 14

36 12.3 Systems containing apparatus not separately evaulated to IEC 60079-11 ............. 14

37 12.4 Systems containing a single power source ............................................................ 14

38 12.5 Systems containing more than one power source .................................................. 14

39 12.5.1 General ......................................................................................................... 14

40 12.5.2 Systems containing linear and non-linear sources of power ........................... 14

41 12.6 Simple apparatus .................................................................................................. 16

42 12.7 Assessment of capacitance, inductance and cable L/R ......................................... 17

43 12.7.1 General ......................................................................................................... 17

44 12.7.2 Unspecified Parameters ................................................................................. 17

45 12.7.3 Output Parameter adjustments for Level of Protection ................................... 17

46 12.7.4 Effect of combined lumped capacitance and inductance ................................ 17

47 12.7.5 Determination of L/R ...................................................................................... 17

48 12.8 Faults in multi-circuit cables .................................................................................. 18

49 12.9 Type verifications and type tests ........................................................................... 18

50 13 Predefined systems ....................................................................................................... 18

51 Annex A (informative) Assessment of a simple intrinsically safe system ............................... 19

52 Annex B (informative) Assessment of circuits with more than one power source .................. 21

53 Annex C (informative) Interconnection of non-linear and linear intrinsically safe circuits ...... 24

54 C.1 General ................................................................................................................. 24

55 C.2 Assessment of the output characteristics of the power sources ............................. 24

57 characteristics ...................................................................................................... 27

58 C.4 Determination of intrinsic safety and the use of graphs ......................................... 30

59 C.5 Verification against IEC 60079-11 ......................................................................... 31

60 C.6 Illustration of the procedure .................................................................................. 31

61 C.7 Diagrams .............................................................................................................. 35

62 Annex D (normative) Verification of inductive parameters .................................................... 46

63 Annex E (informative) Example format for a descriptive system document ........................... 48

64 Annex F (informative) Use of simple apparatus in systems .................................................. 50

65 F.1 General ................................................................................................................. 50

66 F.2 Use of apparatus with ‘simple apparatus’ .............................................................. 51

67 Annex G (normative) FISCO systems ................................................................................... 52

68 G.1 General ................................................................................................................. 52

69 G.2 System requirements ............................................................................................ 52

70 G.2.1 General ......................................................................................................... 52

71 G.3 Additional requirements of “ic” FISCO systems ..................................................... 53

73 Figure 1 – Systems analysis ................................................................................................. 16

74 Figure B.1 – Power sources connected in series ................................................................... 22

75 Figure B.2 – Power sources connected in parallel ................................................................. 23

76 Figure B.3 – Power sources not deliberately connected ........................................................ 23

77 Figure C.1 – Equivalent circuit and output characteristic of resistive circuits ......................... 25

78 Figure C.2 – Output characteristic and equivalent circuit of a source with trapezoidal

79 characteristic ........................................................................................................................ 27

80 Figure C.3 – Current and/or voltage addition for interconnections ......................................... 30

81 Figure C.4 – Example of an interconnection .......................................................................... 32

82 Figure C.5 – Sum characteristics for the circuit as given in Figure C.4 .................................. 33

83 Figure C.6 – Current and/or voltage addition for the example given in Figure C.4 ................. 34

84 Figure C.7 – Limit curve diagram for universal source characteristic − Group IIC .................. 40

85 Figure C.8 – Limit curve diagram for universal source characteristic – Group IIB .................. 45

86 Figure D.1 – Typical inductive circuit .................................................................................... 47

87 Figure E.1 – Typical block diagram for IS system descriptive system document ................... 49

88 Figure G.1 – Typical system ................................................................................................. 54

90 Table A.1 – Simple system analysis ...................................................................................... 20

91 Table C.1 – Parameters necessary to describe the output characteristic ............................... 25

92 Table C.2 – Assignment of diagrams to equipment Groups and inductances ......................... 30

104 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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106 international co-operation on all questions concerning standardization in the electrical and electronic fields. To

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112 with the International Organization for Standardization (ISO) in accordance with conditions determined by

114 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

115 consensus of opinion on the relevant subjects since each technical committee has representation from all

117 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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125 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

126 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

128 6) All users should ensure that they have the latest edition of this publication.

129 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

130 members of its technical committees and IEC National Committees for any personal injury, property damage or

131 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

132 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

134 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

136 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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

138 International Standard IEC 60079-25 has been prepared by subcommittee 31G: Intrinsically

139 safe apparatus, of IEC technical committee 31: Equipment for explosive atmospheres.

140 This third edition cancels and replaces the second edition published in 2010 and constitutes a

142 The significance of the changes between IEC Standard, IEC 60079-25, Edition 2 (2010) and

145 NOTE: The technical changes referred to include the significance of technical changes in the revised IEC

146 Standard, but they do not form an exhaustive list of all modifications from the previous version. More guidance

154 These are changes which modify requirements in an editorial or a minor technical way. They

155 include changes of the wording to clarify technical requirements without any technical change,

158 These are changes which add new or modify existing technical requirements, in a way that

159 new options are given, but without increasing requirements for equipment that was fully

160 compliant with the previous standard. Therefore, these will not have to be considered for

164 These are changes to technical requirements (addition, increase of the level or removal)

165 made in a way that a product in conformity with the preceding edition will not always be able

166 to fulfil the requirements given in the later edition. These changes have to be considered for

167 products in conformity with the preceding edition. For these changes additional information is

169 Note: These changes represent current technological knowledge. However, these changes should not normally

172 C1 – Most of the earthing and bonding requirements have been moved to IEC 60079-14, and

173 the surge protection requirements that were in the old Clause 12 were added here in Clause

174 11. The rest of the old Clause 12 was also removed and moved to IEC 60079-14

175 C2 – The former Annex F on surge protection has been removed and will be covered in IEC

176 60079-14, Annex F is now Simple Apparatus, which was Annex H in the previous edition

179 Full information on the voting for the approval of this standard can be found in the report on

181 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

182 A list of all parts of IEC 60079 series, under the general title Explosive atmospheres, can be

184 The committee has decided that the contents of this publication will remain unchanged until

185 the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

200 This part of IEC 60079 contains the specific requirements for design, construction and

201 assessment of intrinsically safe systems, Type of Protection “i”, intended for use, as a whole

202 or in part, in locations in which the use of Group I, II or III Ex Equipment is required.

203 NOTE 1 This standard is intended for use by the designer of the system who may be a manufacturer, a specialist

205 This document supplements and modifies the general requirements of IEC 60079-0 and the

206 intrinsic safety standard IEC 60079-11. Where a requirement of this standard conflicts with a

207 requirement of IEC 60079-0 or IEC 60079-11, the requirement of this standard takes

209 This document supplements IEC 60079-11, the requirements of which apply to apparatus

211 The installation requirements of Group II or Group III systems designed in accordance with

213 NOTE 2 Group I installation requirements are presently not provided in IEC 60079-14. Installation requirements

216 The following referenced documents are indispensable for the application of this document.

217 For dated references, only the edition cited applies. For undated references, the latest edition

219 IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements

220 IEC 60079-11, Explosive atmospheres – Part 11: Equipment protection by intrinsic safety “i”

221 IEC 60079-14, Explosive atmospheres – Part 14: Electrical installations design, selection

223 IEC 61158-2, Industrial communication networks − Fieldbus specifications – Part 2: Physical

226 For the purposes of this document, the following terms and definitions, specific to intrinsically

227 safe systems, apply. They supplement the terms and definitions which are given in IEC

229 ISO and IEC maintain terminological databases for use in standardization at the following

235 assembly of interconnected items of apparatus, described in a descriptive system document,

236 in which the circuits or parts of circuits, intended to be used in an explosive atmosphere, are

243 document in which the items of apparatus, their intrinsic safety parameters and those of the

248 total capacitance of the interconnecting cable that can be connected into an intrinsically safe

253 total inductance of the interconnecting cable that can be connected into an intrinsically safe

258 value of the ratio inductance (L ) to resistance (R ) of the interconnecting cable connected

262 power source from which the available output current is determined by a resistor; the output

266 power source where the output voltage and output current have a non-linear relationship

267 Note 1 to entry: For example, a supply with a constant voltage output that can reach a constant current limit

272 intrinsically safe system architecture which is bus-powered and designed in accordance with

273 IEC 61558-2, Industrial communication networks − Fieldbus specifications – Part 2: Physical

276 A descriptive system document shall be created for all intrinsically safe systems. The