IEC 60079-11:2023
(Main)Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"
Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"
IEC 60079-11:2023 specifies the construction and testing of intrinsically safe apparatus intended for use in explosive atmospheres, and for associated apparatus which is intended for connection to intrinsically safe circuits which enter such atmospheres.
This Type of Protection is applicable to electrical equipment in which the electrical circuits themselves are incapable of causing ignition of a surrounding explosive atmosphere. This includes electrical equipment which contains circuits that are intrinsically safe only under certain conditions, for example under battery supply with mains supply removed.
This document is also applicable to electrical equipment or parts of electrical equipment located outside the explosive atmosphere or protected by another Type of Protection listed in IEC 60079 0, where the intrinsic safety of the electrical circuits in the explosive atmosphere may depend upon the design and construction of such electrical equipment or parts of such electrical equipment. The electrical circuits exposed to the explosive atmosphere are assessed for use in such atmospheres by applying this document.
This document applies to sensors connected to intrinsically safe circuits but does not apply to the protection of catalytic elements for Group IIC or Group IIB + H2.
This document does not apply to Ex Equipment cable glands.
The requirements for intrinsically safe systems are provided in IEC 60079-25.
This document supplements and modifies the general requirements of IEC 60079-0, except as indicated in Table 1. Where a requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of this document takes precedence.
Unless otherwise stated, the requirements in this document are applicable to both intrinsically safe apparatus and associated apparatus, and the generic term "apparatus" is used throughout the standard.
As this document applies only to electrical equipment, the term "equipment" used in the standard always means "electrical equipment".
This document applies to apparatus for use under the atmospheric conditions of IEC 60079 0 with additional requirements for use at extended atmospheric pressures in the range from 60 kPa (0,6 bar), up to 110 kPa (1,1 bar).
This seventh edition cancels and replaces the sixth edition published in 2011. This edition constitutes a technical revision.
The identification and significance of the changes between IEC 60079-11, Edition 7 (2022) and IEC 60079-11, Edition 6 (2011 + Corrigendum 1 (2012)) can be found in the table of changes in the foreword of the publication.
The contents of the corrigendum of June 2023 have been included in this copy.
Atmosphères explosives - Partie 11: Protection de l’appareil par sécurité intrinsèque "i"
IEC 60079-11:2023 spécifie la construction et les essais pour le matériel électrique de sécurité intrinsèque destiné à être utilisé dans les atmosphères explosives et pour le matériel électrique associé destiné à être relié à des circuits de sécurité intrinsèque qui entrent dans de telles atmosphères.
Ce mode de protection s’applique à l’appareil électrique dont les circuits électriques sont eux mêmes incapables de provoquer une inflammation dans l’atmosphère explosive environnante. Il inclut l’appareil électrique qui contient des circuits qui sont de sécurité intrinsèque uniquement dans certaines conditions, par exemple alimentés par batterie et alimentation réseau coupée.
Le présent document s’applique également à l’appareil électrique ou aux parties d’appareil électrique situés hors de l’atmosphère explosive ou protégés par un autre mode de protection cité dans l’IEC 60079 0, si la sécurité intrinsèque des circuits électriques situés dans l’atmosphère explosive peut dépendre de la conception et de la construction de cet appareil électrique ou de ces parties d’appareil électrique. Les circuits électriques exposés à une atmosphère explosive sont évalués en vue de leur emploi dans de telles atmosphères en appliquant le présent document.
Le présent document s’applique aux capteurs reliés à des circuits de sécurité intrinsèque, mais elle ne s’applique pas à la protection d’éléments catalytiques pour le Groupe IIC ou le Groupe IIB + H2.
Le présent document ne s’applique pas aux entrées de câbles d’appareils Ex.
Les exigences pour les circuits de sécurité intrinsèque sont fournies dans l’IEC 60079-25.
Le présent document complète et modifie les exigences générales de l’IEC 60079-0. Si une exigence du présent document entre en conflit avec une exigence de l’IEC 60079-0, l’exigence du présent document prévaut.
Sauf indication contraire, les exigences du présent document s’appliquent au matériel de sécurité intrinsèque et au matériel associé, et le terme générique "matériel" est utilisé dans toute la norme.
Comme le présent document s’applique uniquement à l’appareil électrique, le terme "appareil" utilisé dans la norme signifie toujours "appareil électrique".
Le présent document s’applique au matériel à utiliser dans les conditions atmosphériques de l’IEC 60079-0 avec les exigences supplémentaires pour son utilisation à des pressions atmosphériques supérieures comprises entre 60 kPa (0,6 bar) et 110 kPa (1,1 bar).
Cette septième édition annule et remplace la sixième édition parue en 2011. Cette édition constitue une révision technique
L'identification et la signification des changements entre la CEI 60079-11, Édition 7 (2022) et la CEI 60079-11, Édition 6 (2011 + Corrigendum 1 (2012)) peuvent être trouvées dans le tableau des modifications dans l'avant-propos de la publication
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Copyright © 2023 IEC, Geneva, Switzerland
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IEC 60079-11
®
Edition 7.0 2023-01
INTERNATIONAL
STANDARD
colour
inside
Explosive atmospheres –
Part 11: Equipment protection by intrinsic safety "i"
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.260.20 ISBN 978-2-8322-6271-9
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC 60079-11:2023 © IEC 2023
CONTENTS
FOREWORD . 10
1 Scope . 23
2 Normative references . 30
3 Terms, definitions and abbreviated terms . 31
3.1 Terms and definitions . 31
3.2 Abbreviated terms . 35
4 Equipment grouping, classification and Levels of Protection of apparatus . 35
5 Ignition compliance requirements . 36
5.1 General . 36
5.2 Conditions for assessment . 36
5.2.1 General . 36
5.2.2 Level of Protection "ia" . 37
5.2.3 Level of Protection "ib" . 38
5.2.4 Level of Protection "ic". 38
5.2.5 Non-shock hazard equipment or systems . 39
5.3 Spark ignition compliance . 39
5.3.1 General . 39
5.3.2 Levels of Protection "ia" and "ib" . 40
5.3.3 Level of Protection "ic". 40
5.3.4 Application of safety factors . 41
5.3.5 Circuits without controlled semiconductor limitation . 41
5.3.6 Circuits with controlled semiconductor limitation . 42
5.4 Thermal ignition compliance . 43
5.4.1 General . 43
5.4.2 Temperature of small components for Group I and Group II . 43
5.4.3 Wiring within intrinsically safe apparatus for Group I and Group II . 43
5.4.4 PCB tracks for Group I and Group II . 45
5.4.5 Intrinsically safe apparatus and component temperature for dusts . 48
5.5 Simple apparatus . 48
6 Apparatus construction . 49
6.1 General . 49
6.2 Enclosures . 49
6.2.1 General . 49
6.2.2 Apparatus complying with Table 7 . 50
6.2.3 Apparatus complying with Table 8 or Table 9 . 50
6.2.4 Enclosures for Group IIIC intrinsically safe apparatus . 50
6.2.5 Protection of separations . 50
6.3 Connection facilities for external circuits . 51
6.3.1 Terminals . 51
6.3.2 Earth Terminals . 53
6.3.3 Plugs and sockets . 53
6.3.4 Permanently connected cable . 53
6.3.5 Connections and accessories for intrinsically safe apparatus for use in
non-hazardous area . 54
6.4 Internal connections and connectors . 55
6.4.1 General . 55
6.4.2 Infallible connections . 55
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IEC 60079-11:2023 © IEC 2023 – 3 –
6.4.3 Connectors for internal connections, plug-in cards and components . 57
6.4.4 Earth conductors and connections . 57
6.5 Separation of conductive parts . 58
6.5.1 Separations on which intrinsic safety depends . 58
6.5.2 Separation distances according to Table 7. 58
6.5.3 Reduced separation distances . 59
6.5.4 Failure of separations . 59
6.5.5 Voltage between conductive parts . 65
6.5.6 Types of separation . 65
6.5.7 Composite separations . 72
6.5.8 Printed circuit board assemblies . 73
6.5.9 Separation by metal parts . 75
6.5.10 Separation by non-metallic insulating partitions . 75
6.5.11 Insulation of internal wiring . 76
6.6 Encapsulation . 76
6.6.1 General . 76
6.6.2 Encapsulation used for the exclusion of explosive atmospheres . 77
6.6.3 Mechanical protection to avoid access to parts . 80
6.6.4 Encapsulation used for protection of a fuse . 81
6.6.5 Encapsulation used to provide separation . 81
6.6.6 Encapsulation used to enhance the rating of protective components . 81
6.6.7 Free space within the encapsulation . 81
6.7 Specification of coating, encapsulation materials . 83
6.8 Protection against polarity reversal . 83
6.9 Dielectric strength requirement . 83
7 Characteristics and failure of components and assemblies . 84
7.1 Rating of components on which intrinsic safety depends . 84
7.2 Failure of components . 84
7.3 Manufacturing variation . 84
7.4 Resistors . 85
7.4.1 General . 85
7.4.2 Resistors on which intrinsic safety depends . 85
7.5 Capacitors . 86
7.5.1 General . 86
7.5.2 Capacitors on which intrinsic safety depends . 86
7.5.3 Blocking capacitors . 87
7.5.4 Infallible filter capacitors . 87
7.6 Inductors and windings . 88
7.6.1 General . 88
7.6.2 Inductors on which intrinsic safety depends . 88
7.6.3 Infallibly insulated inductors . 88
7.6.4 Damping windings . 89
7.6.5 Common mode choke coils (EMI suppression filters) . 89
7.7 Semiconductors . 90
7.7.1 Failure of semiconductors . 90
7.7.2 Semiconductors on which intrinsic safety depends . 91
7.7.3 Transient effects on semiconductors on which intrinsic safety depends . 91
7.7.4 Semiconductors in shunt voltage limiters . 91
7.7.5 Shunt assembly on which intrinsic safety depends . 92
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– 4 – IEC 60079-11:2023 © IEC 2023
7.7.6 Safety assemblies infallible against failure to limit voltage . 92
7.7.7 Semiconductor current limiters . 92
7.7.8 Use of programmable components . 92
7.8 Transformers . 93
7.8.1 General . 93
7.8.2 Transformers on which intrinsic safety depends . 93
7.8.3 Construction of transformers on which intrinsic safety depends . 93
7.8.4 Protective measures for transformers on which intrinsic safety depends
for Levels of Protection "ia" and "ib" . 94
7.8.5 Requirements for transformers for Level of Protection "ic" . 95
7.9 Relays . 95
7.9.1 General . 95
7.9.2 Relays on which intrinsic safety depends . 96
7.10 Signal isolators . 97
7.10.1 General . 97
7.10.2 Signal isolators on which intrinsic safety depends . 97
7.10.3 Signal isolators between intrinsically safe and non-intrinsically safe
circuits . 98
7.10.4 Signal isolators between separate intrinsically safe circuits . 98
7.11 Fuses. 98
7.12 Primary and secondary cells and batteries . 100
7.12.1 General . 100
7.12.2 Construction of cells and batteries used in intrinsically safe apparatus . 100
7.12.3 Electrolyte leakage . 101
7.12.4 Ventilation . 101
7.12.5 Cell voltages . 101
7.12.6 Batteries in equipment protected by different Types of Protection . 102
7.12.7 Batteries used and replaced in explosive atmospheres . 102
7.12.8 Replaceable batteries used but not replaced in explosive atmospheres . 102
7.12.9 External contacts for charging batteries . 102
7.13 Piezoelectric devices . 102
7.14 Cells for the detection of gases . 103
7.14.1 Electrochemical . 103
7.14.2 Catalytic . 103
7.15 Supercapacitors . 103
7.16 Thermal devices . 104
7.16.1 General . 104
7.16.2 Thermal devices used to limit temperature . 104
7.16.3 PPTC devices used to limit current . 105
7.17 Mechanical switches . 106
8 Supplementary requirements for specific apparatus . 106
8.1 Diode safety barriers . 106
8.1.1 General . 106
8.1.2 Construction . 106
8.2 FISCO apparatus . 106
9 Type verifications and type tests. 107
9.1 Spark ignition test . 107
9.1.1 General . 107
9.1.2 Spark test apparatus and its use . 107
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IEC 60079-11:2023 © IEC 2023 – 5 –
9.1.3 Test gas mixtures and spark test apparatus calibration current . 108
9.2 Spark ignition assessment using reference curves and tables . 109
9.2.1 General . 109
9.2.2 Assessment of simple resistive circuit . 109
9.2.3 Assessment of simple capacitive circuits . 110
9.2.4 Assessment of Simple Inductive Circuits . 112
9.2.5 Determination of L /R for resistance limited power source . 113
o o
9.2.6 Circuits with both inductance and capacitance . 114
9.3 Temperature tests . 114
9.4 Mechanical tests . 115
9.4.1 Casting compound . 115
9.4.2 Acceptability of encapsulated or coated fuses. 115
9.4.3 Partitions . 116
9.4.4 Cable pull test . 116
9.5 Current carrying capacity of infallible printed circuit board connections . 116
9.6 Dielectric strength tests . 116
9.7 Qualification of solid insulation and distance through casting compound for
application of reduced separations . 116
9.7.1 General . 116
9.7.2 Preconditioning . 117
9.7.3 AC power frequency voltage test . 117
9.7.4 Partial discharge test . 118
9.8 Type tests for PCB coatings . 119
9.9 Differential Leakage current tests for signal isolators . 119
9.10 Isolator tests . 120
9.10.1 General . 120
9.10.2 Thermal conditioning and dielectric test . 120
9.10.3 Dielectric and short circuit test . 121
9.11 Tests for intrinsically safe apparatus containing piezoelectric devices . 122
9.12 Tests for PTC devices . 122
9.13 Determination of parameters of loosely specified components . 123
9.14 Tests for cells, batteries and supercapacitors . 123
9.14.1 Conditions for testing . 123
9.14.2 Electrolyte leakage test for cells, batteries and supercapacitors . 124
9.14.3 Spark ignition and surface temperature of cells, batteries or
supercapacitors . 125
9.14.4 Battery container pressure tests . 126
9.14.5 Battery resistance . 126
9.15 Determination of storable energy in common mode chokes . 126
9.16 Type tests for components protected by time dependent current limitation . 128
9.17 Transformer tests . 129
9.17.1 General . 129
9.17.2 Mains transformers for Level of Protection "ia" and "ib" . 130
9.17.3 Transformers galvanically isolated from the mains supply for Levels of
Protection "ia" and "ib" . 130
9.17.4 Transformers for Level of Protection "ic" . 131
10 Routine verifications and tests . 131
10.1 Alternative reduced spacings . 131
10.2 Routine tests for diode safety barriers . 131
---------------------- Page: 7 ----------------------
– 6 – IEC 60079-11:2023 © IEC 2023
10.2.1 Completed barriers . 131
10.2.2 Diodes for 2-diode "ia" barriers . 131
10.3 Routine tests for transformers . 131
10.3.1 Levels of Protection "ia" and "ib" . 131
10.3.2 Level of Protection "ic". 132
10.4 Routine verification of conformal coating and encapsulation . 132
11 Marking . 133
11.1 Intrinsically safe apparatus and associated apparatus . 133
11.1.1 General . 133
11.1.2 Intrinsic safety parameters . 133
11.1.3 FISCO . 133
11.1.4 Marking of connection facilities . 134
11.1.5 Non-hazardous area accessory. 134
11.2 Warning markings . 134
12 Instructions . 135
12.1 General . 135
12.2 Specific Conditions of Use . 135
Annex A (normative) Spark ignition reference curves . 137
Annex B (normative) Spark test apparatus for intrinsically safe circuits . 161
B.1 Principle . 161
B.2 Spark test apparatus . 161
B.3 Spark test apparatus sensitivity . 162
B.4 Preparation and cleaning of tungsten wires . 162
B.5 Conditioning a new cadmium disc . 163
B.6 Limitations of the spark test apparatus . 163
B.7 Modification of spark test apparatus for use at higher currents . 164
Annex C (informative) Measurement of creepage distances, clearances and
separation distances through casting compound and through solid insulation . 169
C.1 Clearances and separation distances through casting compound and
through solid insulation . 169
C.2 Creepage distances . 170
C.3 Examples for the application of an ambient pressure correction factor . 171
Annex D (normative) Excess transient energy test . 174
D.1 Overview. 174
D.2 Circuit configuration . 175
D.3 Test equipment . 176
D.4 Test load . 177
D.5 Supply voltage .
...
IEC 60079-11
®
Edition 7.0 2023-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Explosive atmospheres –
Part 11: Equipment protection by intrinsic safety "i"
Atmosphères explosives –
Partie 11: Protection de l’appareil par sécurité intrinsèque "i"
IEC 60079-11:2023-01(en-fr)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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International Standards for all electrical, electronic and related technologies.
About IEC publications
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latest edition, a corrigendum or an amendment might have been published.
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IEC 60079-11
®
Edition 7.0 2023-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Explosive atmospheres –
Part 11: Equipment protection by intrinsic safety "i"
Atmosphères explosives –
Partie 11: Protection de l’appareil par sécurité intrinsèque "i"
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-7447-7
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 60079-11:2023 © IEC 2023
CONTENTS
FOREWORD . 10
1 Scope . 23
2 Normative references . 30
3 Terms, definitions and abbreviated terms . 31
3.1 Terms and definitions . 31
3.2 Abbreviated terms . 35
4 Equipment grouping, classification and Levels of Protection of apparatus . 35
5 Ignition compliance requirements . 36
5.1 General . 36
5.2 Conditions for assessment . 36
5.2.1 General . 36
5.2.2 Level of Protection "ia" . 37
5.2.3 Level of Protection "ib" . 38
5.2.4 Level of Protection "ic". 38
5.2.5 Non-shock hazard equipment or systems . 39
5.3 Spark ignition compliance . 39
5.3.1 General . 39
5.3.2 Levels of Protection "ia" and "ib" . 40
5.3.3 Level of Protection "ic". 40
5.3.4 Application of safety factors . 41
5.3.5 Circuits without controlled semiconductor limitation . 41
5.3.6 Circuits with controlled semiconductor limitation . 42
5.4 Thermal ignition compliance . 43
5.4.1 General . 43
5.4.2 Temperature of small components for Group I and Group II . 43
5.4.3 Wiring within intrinsically safe apparatus for Group I and Group II . 43
5.4.4 PCB tracks for Group I and Group II . 45
5.4.5 Intrinsically safe apparatus and component temperature for dusts . 48
5.5 Simple apparatus . 48
6 Apparatus construction . 49
6.1 General . 49
6.2 Enclosures . 49
6.2.1 General . 49
6.2.2 Apparatus complying with Table 7 . 50
6.2.3 Apparatus complying with Table 8 or Table 9 . 50
6.2.4 Enclosures for Group IIIC intrinsically safe apparatus . 50
6.2.5 Protection of separations . 50
6.3 Connection facilities for external circuits . 51
6.3.1 Terminals . 51
6.3.2 Earth Terminals . 53
6.3.3 Plugs and sockets . 53
6.3.4 Permanently connected cable . 53
6.3.5 Connections and accessories for intrinsically safe apparatus for use in
non-hazardous area . 54
6.4 Internal connections and connectors . 55
6.4.1 General . 55
6.4.2 Infallible connections . 55
---------------------- Page: 4 ----------------------
IEC 60079-11:2023 © IEC 2023 – 3 –
6.4.3 Connectors for internal connections, plug-in cards and components . 57
6.4.4 Earth conductors and connections . 57
6.5 Separation of conductive parts . 58
6.5.1 Separations on which intrinsic safety depends . 58
6.5.2 Separation distances according to Table 7. 58
6.5.3 Reduced separation distances . 59
6.5.4 Failure of separations . 59
6.5.5 Voltage between conductive parts . 65
6.5.6 Types of separation . 65
6.5.7 Composite separations . 72
6.5.8 Printed circuit board assemblies . 73
6.5.9 Separation by metal parts . 75
6.5.10 Separation by non-metallic insulating partitions . 75
6.5.11 Insulation of internal wiring . 76
6.6 Encapsulation . 76
6.6.1 General . 76
6.6.2 Encapsulation used for the exclusion of explosive atmospheres . 77
6.6.3 Mechanical protection to avoid access to parts . 80
6.6.4 Encapsulation used for protection of a fuse . 81
6.6.5 Encapsulation used to provide separation . 81
6.6.6 Encapsulation used to enhance the rating of protective components . 81
6.6.7 Free space within the encapsulation . 81
6.7 Specification of coating, encapsulation materials . 83
6.8 Protection against polarity reversal . 83
6.9 Dielectric strength requirement . 83
7 Characteristics and failure of components and assemblies . 84
7.1 Rating of components on which intrinsic safety depends . 84
7.2 Failure of components . 84
7.3 Manufacturing variation . 84
7.4 Resistors . 85
7.4.1 General . 85
7.4.2 Resistors on which intrinsic safety depends . 85
7.5 Capacitors . 86
7.5.1 General . 86
7.5.2 Capacitors on which intrinsic safety depends . 86
7.5.3 Blocking capacitors . 87
7.5.4 Infallible filter capacitors . 87
7.6 Inductors and windings . 88
7.6.1 General . 88
7.6.2 Inductors on which intrinsic safety depends . 88
7.6.3 Infallibly insulated inductors . 88
7.6.4 Damping windings . 89
7.6.5 Common mode choke coils (EMI suppression filters) . 89
7.7 Semiconductors . 90
7.7.1 Failure of semiconductors . 90
7.7.2 Semiconductors on which intrinsic safety depends . 91
7.7.3 Transient effects on semiconductors on which intrinsic safety depends . 91
7.7.4 Semiconductors in shunt voltage limiters . 91
7.7.5 Shunt assembly on which intrinsic safety depends . 92
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7.7.6 Safety assemblies infallible against failure to limit voltage . 92
7.7.7 Semiconductor current limiters . 92
7.7.8 Use of programmable components . 92
7.8 Transformers . 93
7.8.1 General . 93
7.8.2 Transformers on which intrinsic safety depends . 93
7.8.3 Construction of transformers on which intrinsic safety depends . 93
7.8.4 Protective measures for transformers on which intrinsic safety depends
for Levels of Protection "ia" and "ib" . 94
7.8.5 Requirements for transformers for Level of Protection "ic" . 95
7.9 Relays . 95
7.9.1 General . 95
7.9.2 Relays on which intrinsic safety depends . 96
7.10 Signal isolators . 97
7.10.1 General . 97
7.10.2 Signal isolators on which intrinsic safety depends . 97
7.10.3 Signal isolators between intrinsically safe and non-intrinsically safe
circuits . 98
7.10.4 Signal isolators between separate intrinsically safe circuits . 98
7.11 Fuses. 98
7.12 Primary and secondary cells and batteries . 100
7.12.1 General . 100
7.12.2 Construction of cells and batteries used in intrinsically safe apparatus . 100
7.12.3 Electrolyte leakage . 101
7.12.4 Ventilation . 101
7.12.5 Cell voltages . 101
7.12.6 Batteries in equipment protected by different Types of Protection . 102
7.12.7 Batteries used and replaced in explosive atmospheres . 102
7.12.8 Replaceable batteries used but not replaced in explosive atmospheres . 102
7.12.9 External contacts for charging batteries . 102
7.13 Piezoelectric devices . 102
7.14 Cells for the detection of gases . 103
7.14.1 Electrochemical . 103
7.14.2 Catalytic . 103
7.15 Supercapacitors . 103
7.16 Thermal devices . 104
7.16.1 General . 104
7.16.2 Thermal devices used to limit temperature . 104
7.16.3 PPTC devices used to limit current . 105
7.17 Mechanical switches . 106
8 Supplementary requirements for specific apparatus . 106
8.1 Diode safety barriers . 106
8.1.1 General . 106
8.1.2 Construction . 106
8.2 FISCO apparatus . 106
9 Type verifications and type tests. 107
9.1 Spark ignition test . 107
9.1.1 General . 107
9.1.2 Spark test apparatus and its use . 107
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9.1.3 Test gas mixtures and spark test apparatus calibration current . 108
9.2 Spark ignition assessment using reference curves and tables . 109
9.2.1 General . 109
9.2.2 Assessment of simple resistive circuit . 109
9.2.3 Assessment of simple capacitive circuits . 110
9.2.4 Assessment of Simple Inductive Circuits . 112
9.2.5 Determination of L /R for resistance limited power source . 113
o o
9.2.6 Circuits with both inductance and capacitance . 114
9.3 Temperature tests . 114
9.4 Mechanical tests . 115
9.4.1 Casting compound . 115
9.4.2 Acceptability of encapsulated or coated fuses. 115
9.4.3 Partitions . 116
9.4.4 Cable pull test . 116
9.5 Current carrying capacity of infallible printed circuit board connections . 116
9.6 Dielectric strength tests . 116
9.7 Qualification of solid insulation and distance through casting compound for
application of reduced separations . 116
9.7.1 General . 116
9.7.2 Preconditioning . 117
9.7.3 AC power frequency voltage test . 117
9.7.4 Partial discharge test . 118
9.8 Type tests for PCB coatings . 119
9.9 Differential Leakage current tests for signal isolators . 119
9.10 Isolator tests . 120
9.10.1 General . 120
9.10.2 Thermal conditioning and dielectric test . 120
9.10.3 Dielectric and short circuit test . 121
9.11 Tests for intrinsically safe apparatus containing piezoelectric devices . 122
9.12 Tests for PTC devices . 122
9.13 Determination of parameters of loosely specified components . 123
9.14 Tests for cells, batteries and supercapacitors . 123
9.14.1 Conditions for testing . 123
9.14.2 Electrolyte leakage test for cells, batteries and supercapacitors . 124
9.14.3 Spark ignition and surface temperature of cells, batteries or
supercapacitors . 125
9.14.4 Battery container pressure tests . 126
9.14.5 Battery resistance . 126
9.15 Determination of storable energy in common mode chokes . 126
9.16 Type tests for components protected by time dependent current limitation . 128
9.17 Transformer tests . 129
9.17.1 General . 129
9.17.2 Mains transformers for Level of Protection "ia" and "ib" . 130
9.17.3 Transformers galvanically isolated from the mains supply for Levels of
Protection "ia" and "ib" . 130
9.17.4 Transformers for Level of Protection "ic" . 131
10 Routine verifications and tests . 131
10.1 Alternative reduced spacings . 131
10.2 Routine tests for diode safety barriers . 131
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10.2.1 Completed barriers . 131
10.2.2 Diodes for 2-diode "ia" barriers . 131
10.3 Routine tests for transformers . 131
10.3.1 Levels of Protection "ia" and "ib" . 131
10.3.2 Level of Protection "ic". 132
10.4 Routine verification of conformal coating and encapsulation . 132
11 Marking . 133
11.1 Intrinsically safe apparatus and associated apparatus . 133
11.1.1 General . 133
11.1.2 Intrinsic safety parameters . 133
11.1.3 FISCO . 133
11.1.4 Marking of connection facilities . 134
11.1.5 Non-hazardous area accessory. 134
11.2 Warning markings .
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