SIST EN 61241-11:2007
(Main)Electrical apparatus for use in the presence of combustible dust -- Part 11: Protection by intrinsic safety iD
Electrical apparatus for use in the presence of combustible dust -- Part 11: Protection by intrinsic safety iD
This part of IEC 61241 is intended to be applied by users and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only. It does not include conventional requirements for electrical installations, nor the testing and certification of electrical apparatus. This standard supplements the requirements laid down in IEC 60364-6-61. This standard assumes effective housekeeping based on a system of cleaning for the plant. The principles of this standard can also be followed when combustible fibres or flyings may cause a hazard. This standard is intended to be applied where there can be a risk due to the presence of explosive dust/air mixtures or combustible dust layers under normal atmospheric conditions. It does not apply to - underground mining areas, - areas where a risk can arise due to the presence of hybrid mixtures, - dusts of explosives that do not require atmospheric oxygen for combustion, or to - pyrophoric substances.
Elektrische Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub -- Teil 11: Schutz durch Eigensicherheit iD
Matériels électriques pour utilisation en présence de poussières combustibles -- Partie 11: Protection par sécurité intrinsèque iD
Cette partie de la EN 61241 spécifie les exigences relatives à la construction et aux essais des matériels à sécurité intrinsèque destinés à être utilisés dans des environnements de nuage ou de couches de poussières combustibles, et des matériels associés destinés à être connectés à des matériels à sécurité intrinsèque qui entrent dans de tels environnements.
Električne naprave za uporabo v prisotnosti gorljivega prahu - 11. del: Zaščita z lastno varnostjo “iD” (IEC 61241-11:2005 s popravkom feb. 2006)
General Information
Relations
Standards Content (Sample)
SIST EN 61241-11:2007SLOVENSKImarec 2007
STANDARD(OHNWULþQHQDSUDYH]DXSRUDERYSULVRWQRVWLJRUOMLYHJDSUDKXGHO=DãþLWDz lastno varnostjo “iD” (IEC 61241-11:2005 s popravkom feb. 2006)Electrical apparatus for use in the presence of combustible dust - Part 11: Protection by intrinsic safety "iD" (IEC 61241-11:2005 + corrigendum Feb. 2006) !#"$%&'& *+5HIHUHQþQDãWHYLONDSIST EN 61241-11:2007(en)ICS29.260.20
EUROPEAN STANDARD EN 61241-11 NORME EUROPÉENNE
EUROPÄISCHE NORM December 2006
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2006 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61241-11:2006 E
ICS 29.260.20
English version
Electrical apparatus for use in the presence of combustible dust
Part 11: Protection by intrinsic safety "iD" (IEC 61241-11:2005 + corrigendum February 2006)
Matériels électriques pour utilisation en présence de poussières combustibles
Partie 11: Protection par sécurité intrinsèque "iD" (CEI 61241-11:2005
+ corrigendum février 2006)
Elektrische Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub
Teil 11: Schutz durch Eigensicherheit "iD"(IEC 61241-11:2005
+ Corrigendum Februar 2006)
This European Standard was approved by CENELEC on 2005-11-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
EN 61241-11:2006 - 2 - Foreword The text of document 31H/194/FDIS, future edition 1 of IEC 61241-11, prepared by SC 31H, Apparatus for use in the presence of combustible dust, of IEC TC 31, Electrical apparatus for explosive atmospheres, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61241-11 on 2005-11-01. This European Standard is to be read in conjunction with EN 61241-0. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2007-07-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2008-11-01 This European Standard has been prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association and covers essential requirements of EC Directive 94/9/EC. See Annex ZZ. Annexes ZA and ZZ have been added by CENELEC. __________
Endorsement notice The text of the International Standard IEC 61241-11:2005 and its corrigendum February 2006 was approved by CENELEC as a European Standard without any modification. __________
- 3 - EN 61241-11:2006
Annex ZA (normative)
Normative references to international publications with their corresponding European publications
The following referenced documents are indispensable for the application 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.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year IEC 60079-0 (mod) - 1) Electrical apparatus for explosive gas atmospheres
Part 0: General requirements EN 60079-0 2006 2)
IEC 60079-11
- 1) Explosive atmospheres
Part 11: Equipment protection by intrinsic safety "i" EN 60079-11 200X 3)
IEC 60079-25 - 1) Electrical apparatus for explosive gas atmospheres
Part 25: Intrinsically safe systems EN 60079-25 + corr. April
2004 2)2006
IEC 60529 - 1) Degrees of protection provided by
enclosures (IP Code) EN 60529 + corr. May
1991 2)1993
IEC 61241-0 (mod)
- 1) Electrical apparatus for use in the presence of combustible dust
Part 0: General requirements EN 61241-0 2006 2)
IEC 61241-1 - 1) Electrical apparatus for use in the presence of combustible dust
Part 1: Protection by enclosures "tD" EN 61241-1 + corr. December
2004 2)2006
1) Undated reference.
2) Valid edition at date of issue.
3) To be published.
EN 61241-11:2006 - 4 - Annex ZZ (informative)
Coverage of Essential Requirements of EC Directives This European Standard has been prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association and within its scope the standard covers only the following essential requirements out of those given in Annex II of the EC Directive 94/9/EC: – ER 1.0.1, ER 1.0.2, ER 1.0.4, ER 1.0.5 (partly), ER 1.0.6 (partly) – ER 1.1 (partly) – ER 1.2.1 (partly), ER 1.2.2 (partly), ER 1.2.4 to ER 1.2.6 – ER 1.3.1 – ER 1.6.4 – ER 2.1.2, ER 2.1.2.1 to ER 2.1.2.2 – ER 2.2.2.1, ER 2.2.2.2 Compliance with this standard provides one means of conformity with the specified essential requirements of the Directive concerned. WARNING: Other requirements and other EC Directives may be applicable to the products falling within the scope of this standard.
NORME INTERNATIONALECEIIEC INTERNATIONAL STANDARD 61241-11Première éditionFirst edition2005-10 Matériels électriques pour utilisation en présence de poussières combustibles – Partie 11: Protection par sécurité intrinsèque «iD»
Electrical apparatus for use in the presence
of combustible dust – Part 11: Protection by intrinsic safety 'iD'
Pour prix, voir catalogue en vigueur For price, see current catalogue IEC 2005
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61241-11 IEC:2005 – 3 – CONTENTS FOREWORD.5 INTRODUCTION.11 1 Scope.15 2 Normative references.19 3 Terms and definitions.19 4 Grouping and classification of intrinsically safe apparatus and associated apparatus.19 5 Categories of electrical apparatus.19 6 Apparatus construction.21 6.1 Enclosures.21 6.2 Temperatures of apparatus immersed in dust.21 6.3 Facilities for connection of external circuits.23 6.4 Separation distances.25 6.5 Protection against polarity reversal.25 6.6 Earth conductors, connections and terminals.25 6.7 Encapsulation used for exclusion of potentially explosive atmosphere.25 7 Components on which intrinsic safety depends.25 7.1 Rating of components.25 7.2 Connectors for internal connections, plug-in cards and components.25 7.3 Fuses.25 7.4 Primary and secondary cells and batteries.25 7.5 Semiconductors.25 7.6 Failure of components and connections.25 7.7 Piezo-electric devices.25 8 Infallible components, infallible assemblies of components and infallible connections.25 9 Diode safety barriers.27 10 Type verifications, assessments and type tests.27 10.1 Spark ignition assessment.27 10.2 Temperature tests.27 10.3 Voltage tests.27 10.4 Small component ignition test.27 10.5 Determination of parameters of loosely specified components.27 10.6 Tests for cells and batteries.27 10.7 Mechanical test.27 10.8 Tests for apparatus containing piezoelectric devices.29 10.9 Type tests for diode safety barriers and safety shunts.29 10.10 Cable pull test.29 11 Routine verifications and tests.29 12 Marking.29 12.1 General.29 12.2 Marking of connection facilities.31 13 Documentation.33
Annex A (normative)
See Annex B of IEC 60079-11.35 Annex B (informative)
See Annex C of IEC 60079-11.35 Annex C (normative)
See Annex D of IEC 60079-11.35
61241-11 IEC:2005 – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ___________
ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST –
Part 11: Protection by intrinsic safety ‘iD’
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61241-11 has been prepared by subcommittee 31H: Apparatus for use in the presence of combustible dusts, of IEC technical committee 31: Electrical apparatus for explosive atmospheres. The text of this standard is based on the following documents: FDIS Report on voting 31H/194/FDIS 31H/198/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
61241-11 IEC:2005 – 7 – This part of IEC 61241 is to be read in conjunction with IEC 61241-0. IEC 61241 consists of the following parts under the general title Electrical apparatus for use in the presence of combustible dust: Part 0:
General requirements Part 1:
Protection by enclosures “tD” Part 2:
Protection by pressurization “pD” Part 10: Classification of areas where combustible dusts are or may be present Part 11: Protection by intrinsic safety “iD” Part 14: Selection and installation Part 17: Inspection and maintenance of electrical installations in hazardous areas (other than mines) Part 18:
Protection by encapsulation “mD”
Part 20:
Test methods Part 20-1:
Methods for determining the minimum ignition temperatures of dust Part 20-2:
Method for determining the electrical resistivity of dust in layers Part 20-3:
Method for determining minimum ignition energy of dust/air mixtures
NOTE All references in this standard to the IEC 61241 series follow the proposed re-numbering of the dust standards agreed by SC31H and TC31. It may be necessary to alter these numbers if the relevant standards are not yet published. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
The contents of the corrigendum of February 2006 have been included in this copy.
61241-11 IEC:2005 – 9 –
REFERENCE TABLE Existing standard New number assigned Subject Anticipated date of change IEC 61241-0 General requirements 2004 IEC 61241-1-1 IEC 61241-1 Protection by enclosure 2004 IEC 61241-1-2 IEC 61241-14 Selection and installation 2004 IEC 61241-2-1 IEC 61241-20-1 Test methods 2005 IEC 61241-2-2 IEC 61241-20-2 Test methods 2005 IEC 61241-2-3 IEC 61241-20-3 Test methods 2005 IEC 61241-3 IEC 61241-10 Classification 2004 IEC 61241-4 IEC 61241-2 Protection by pressurization 2005
IEC 61241-11 Protection by intrinsic safety 2005
IEC 61241-17 Inspection and maintenance 2004
IEC 61241-18 Protection by encapsulation 2004
61241-11 IEC:2005 – 11 – INTRODUCTION Many dusts which are generated, processed, handled and stored, are combustible. When ignited they can burn rapidly and with considerable explosive force if mixed with air in the appropriate proportions. It is often necessary to use electrical apparatus in locations where such combustible materials are present, and suitable precautions must therefore be taken to ensure that all such apparatus is adequately protected so as to reduce the likelihood of ignition of the external explosive atmosphere. In electrical apparatus, potential ignition sources include electrical arcs and sparks, hot surfaces and frictional sparks. Areas where dusts, flyings and fibres in air occur in dangerous quantities are classified as hazardous and are divided into three zones according to the level of risk. Generally, electrical safety is ensured by the implementation of one of two considerations, i.e. that electrical apparatus be located where reasonably practicable outside hazardous areas and that electrical apparatus be designed, installed and maintained in accordance with measures recommended for the area in which the apparatus is located. Combustible dust can be ignited by electrical apparatus in several main ways: – by surfaces of the apparatus that are above the minimum ignition temperature of the dust concerned. The temperature at which a type of dust ignites is a function of the properties of the dust, whether the dust is in a cloud or layer, the thickness of the layer and the geometry of the heat source; – by arcing or sparking of electrical parts such as switches, contacts, commutators, brushes, or the like; – by discharge of an accumulated electrostatic charge; – by radiated energy (e.g. electromagnetic radiation); – by mechanical sparking or frictional sparking or heating associated with the apparatus. In order to avoid ignition hazards it is necessary that: – the temperature of surfaces, on which dust can be deposited, or which would be in contact with a dust cloud, is kept below the temperature limitation specified in this standard; – any electrical sparking parts, or parts having a temperature above the temperature limit specified in IEC 61241-14
- are contained in an enclosure which adequately prevents the ingress of dust, or - the energy of electrical circuits is limited so as to avoid arcs, sparks or temperatures capable to ignite combustible dust; – any other ignition sources are avoided. Several techniques are available for explosion protection of electrical apparatus in hazardous areas. This standard describes the safety features of this type of explosion-protection technique and specifies the requirements to be adopted. It is most important that the correct selection and installation procedures be followed to ensure the safe use of electrical apparatus in hazardous areas.
61241-11 IEC:2005 – 13 – Compliance with this part of IEC 61241 will only provide the required level of safety if the electrical apparatus is operated within its rating and is installed and maintained according to the relevant codes of practice or requirements, for example in respect of protection against over-currents, internal short-circuits, and other electrical faults. In particular, it is essential that the severity and duration of an internal or external fault be limited to values that can be sustained by the electrical apparatus without damage, for example, installed in a system designed in accordance with the principles of IEC 60079-25 and installed in accordance with IEC 61241-14. The following principles should be followed: – the electronic circuits must fulfil Group IIB requirements according to IEC 60079-11 to avoid spark ignition; – IP 6X or encapsulation is normally required to ensure that creepage and clearance distances are not compromised by dust. Therefore the importance and the durability of the integrity of the enclosure or encapsulation are much higher than required by IEC 60079-11; – There should be power limitation for apparatus or parts of apparatus not protected by an enclosure or encapsulation (e.g. uninsulated sensor) to avoid ignition of a dust layer by power dissipation directly into the dust (power matching by conductive dusts) and to avoid thermal ignition on the surface of components;
– limitation of the temperature of all exposed surfaces of all apparatus or parts of apparatus exceeding the power limitation limits in accordance with IEC 61241-0. The surface can be the surface of the enclosure or of the encapsulation.
61241-11 IEC:2005 – 15 – ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST –
Part 11: Protection by intrinsic safety ‘iD’
1 Scope This part of IEC 61241 specifies requirements for the construction and testing of intrinsically safe apparatus intended for use in potentially explosive dust cloud or dust layer environments and for associated apparatus that is intended for connection to intrinsically safe circuits which enter such environments. This standard supplements the general requirements of IEC 61241-0: except as indicated in the following list. Apparatus utilized in systems will meet the requirements of IEC 60079-25. If associated apparatus is protected by a type of protection listed in IEC 61241-0 or IEC 60079-0 then the requirements of that method of protection together with the relevant parts of IEC 61241 or IEC 60079 also apply to the associated apparatus. The list of exclusions which follows is directly applicable to associated apparatus intended for use in situations where there is no potentially hazardous atmosphere and in other circumstances should be used in combination with the requirements of the other methods of protection. Clause or subclause of IEC 61241-0 Intrinsically safe apparatus Associated apparatus4.1 General Applies Applies 4.2 Principles for design and testing of apparatus for use in Zone 20 Applies Excluded 4.3 Opening enclosures Applies Excluded 4.4 Environmental conditions Applies Excluded 5.1 Maximum surface temperature Applies Excluded 5.2 Maximum surface temperature with respect to dust layers above 50 mm Applies Excluded 5.3 Ambient temperature Applies Applies 6.1 Non-metallic enclosures and non-metallic parts of enclosures Applies Excluded 6.1.1 Material specification Applies Excluded 6.1.2 Plastic materials Applies Excluded 6.1.3 Verification of compliance Applies Excluded 6.1.4 Thermal endurance Applies Excluded 6.1.5 Electrostatic charges
Applies Excluded 6.2 Enclosures containing light metals Applies Excluded 6.2.1 Composition Applies Excluded 6.2.2 Threaded holes Excluded Excluded 7 Fasteners Excluded Excluded 8 Interlocking devices Excluded Excluded 9 Bushings Excluded Excluded
61241-11 IEC:2005 – 17 –
Clause or subclause of IEC 61241-0 Intrinsically safe apparatus Associated apparatus10 Materials used for cementing Applies Excluded 11 Ex components Applies Excluded 12 Connection facilities and terminal compartments Excluded Excluded 13 Connection facilities for earthing or bonding conductors Excluded Excluded 14 Cable and conduit entries Applies Excluded 15 Radiating equipment Applies Excluded 16 Rotating electrical machines Excluded Excluded 17 Switchgear Excluded Excluded 18 Fuses Excluded Excluded 19 Plugs and sockets Excluded Excluded 20 Luminaires Excluded Excluded 21 Caplights, caplamps and handlamps Excluded Excluded 22 Apparatus incorporating cells and batteries Applies Excluded 23.1 to 23.3 Verification and tests Applies Applies 23.4.1 General Applies Excluded 23.4.2.1 Test for resistance to impact
Applies Excluded 23.4.2.2 Drop test
Applies Excluded 23.4.2.3 Verification a Applies Excluded 23.4.3 Test for dust exclusion (degree of protection) Applies Excluded 23.4.4 Torque test for bushings in enclosures for use in Zone 20 or 21 Excluded Excluded 23.4.5.1 Measurement for maximum surface temperature Applies Excluded 23.4.5.2 Measurement for surface temperature under excess layer Applies Excluded 23.4.5.3 Temperature control Applies Excluded 23.4.6 Thermal shock tests Applies Excluded 23.4.7.1 to 23.4.7.5 Tests of non-metallic enclosures or of non-metallic parts of apparatus for use in Zone 20
or 21 Excluded Excluded 23.4.7.6 Mechanical tests Applies Excluded 23.4.7.7 Surface resistivity test Applies Excluded 27 Clamping tests of cable entries for non-armoured and braided cables Excluded Excluded 28 Clamping tests of cable entries for armoured cables Excluded Excluded 29 Marking Applies Applies 30 Examples of marking Applies Applies a IEC 61241-0 pass criteria apply.
61241-11 IEC:2005 – 19 – This part of IEC 61241 is applicable to electrical apparatus in which the electrical circuits themselves are incapable of causing an explosion in the surrounding combustible dust environment. In other circumstances, associated apparatus should be used in combination with the requirements of the other methods of protection listed in IEC 61241-0. 2 Normative references The following referenced documents are indispensable for the application 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 60079-0, Electrical apparatus for potentially explosive atmospheres – Part 0: General requirements IEC 60079-11, Electrical apparatus for explosive gas atmospheres – Part 11: Intrinsic safety “I” IEC 60079-25, Electrical apparatus for explosive gas atmospheres – Part 25: Intrinsically safe systems IEC 60529, Degrees of protection provided by enclosures (IP Code) IEC 61241-0, Electrical apparatus for use in the presence of combustible dust – Part 0: General requirements IEC 61241-1, Electrical apparatus for use in the presence of combustible dust – Part 1: Protection by enclosures “tD” 3 Terms and definitions For the purposes of this document, the terms
and definitions contained in IEC 61241-0, IEC 60079-0 and IEC 60079-11 apply except that where the term “explosive gas atmosphere” is used it shall be interpreted as meaning “combustible dust environment”. 4 Grouping and classification of intrinsically safe apparatus and associated apparatus Intrinsically safe apparatus and associated apparatus shall be grouped and classified in accordance with IEC 61241-0. 5 Categories of electrical apparatus Clause 5 of IEC 60079-11 applies together with the following requirement: Apparatus shall, at a minimum, meet the spark ignition energy level requirements for Group IIB apparatus.
61241-11 IEC:2005 – 21 – 6 Apparatus construction 6.1 Enclosures In principle, intrinsically safe apparatus does not need an enclosure as the method of protection is embodied within the circuits. However, where intrinsic safety can be impaired by access to conducting parts, for example if dust of any type can bridge infallible creepage distances, an enclosure of at least IP6x in accordance with IEC 60529 and as required by IEC 61241-1 shall be provided. In all other circumstances, the degree of protection provided by the enclosure that is required will vary according to the intended purpose of the apparatus. Parts of apparatus not within an enclosure having a degree of protection of at least IP6x that are encapsulated to a depth of at least 1 mm shall be considered to be adequately protected against dust contamination. Where parts of a circuit are not protected by an enclosure or encapsulation as indicated, for example uninsulated sensor circuits in direct contact with the explosive dust atmosphere, they shall be assessed or tested in accordance with this standard assuming that all spacings do not meet the creepage and clearance requi
...
31H/171/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJET DE COMITÉ POUR VOTE (CDV)
Project number 31H/61241-11/Ed. 1
Numéro de projet
IEC/TC or SC: Date of circulation Closing date for voting (Voting mandatory
31H
Date de diffusion for P-members)
CEI/CE ou SC:
Date de clôture du vote (Vote obligatoire
2004-02-06
pour les membres (P))
2004-07-09
Titre du CE/SC: TC/SC Title:
Matériels destinés à être utilisés en présence de Apparatus for use in the presence of
poussières inflammables combustible dust
Secretary: Kerry McManama (USA)
Secrétaire: E-mail: Kerry.McManama@us.ul.com
Also of interest to the following committees Supersedes document
Intéresse également les comités suivants Remplace le document
TC 31
31H/160/NP - 31H/170/RVN
Horizontal functions concerned
Fonctions horizontales concernées
Safety EMC Environment Quality assurance
Sécurité
CEM Environnement Assurance qualité
CE DOCUMENT EST TOUJOURS A L'ÉTUDE ET SUSCEPTIBLE DE MODIFICATION. THIS DOCUMENT IS STILL UNDER STUDY AND SUBJECT TO CHANGE. IT
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AVEC LEURS OBSERVATIONS, LA NOTIFICATION DES DROITS DE PROPRIÉTÉ COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
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DOCUMENTATION EXPLICATIVE.
Titre : Title :
CEI 61241-11, Ed.1 : Matériels électriques
IEC 61241-11, Electrical apparatus for use in
destinés à être utilisés en présence de
the presence of combustible dust - Part 11:
poussières combustibles - Partie 11 : Protection
Protection by intrinsic safety “iD”
par sécurité intrinsèque “iD”
Note d'introduction Introductory note :
ère
Cette 1 Ed. de la CEI 61241-11 introduit la This first edition of IEC 61241-11 introduces the
protection method of “Intrinsically safe” for electrical
méthode de protection par sécurité intrinsèque pour
apparatus for use in the presence of combustible
les matériels électriques destinés à être utilisés en
dust. It aligns with IEC 60079-11 wherever possible.
présence de poussières combustibles. Le paralllèle
The text is mostly identical except where reference
avec la CEI 60079-11 a été réalisé partout où cela
to gases and vapours has been replaced with
était possible. Le texte est pratiquement identique
references to combustible dusts.
excepté la référence aux gaz et aux vapeur qui a été
remplacé par la référence aux poussières
combustibles.
ATTENTION ATTENTION
CDV soumis en parallèle au vote (CEI) Parallel IEC CDV/CENELEC Enquiry
et à l’enquête (CENELEC)
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writing from IEC.
FORM 7B (IEC)
1999-10-01
---------------------- Page: 1 ----------------------
2
61241-11 Ed.1 /CDV IEC – -
CONTENTS
Page
1 Scope.8
2 Normative references .10
3 Definitions .10
4 Grouping and classification of intrinsically safe apparatus and associated
apparatus .10
5 Categories of electrical apparatus .10
6 Apparatus construction.10
6.1 Enclosures .10
6.2 Temperatures of Apparatus immersed in dust.11
6.2.1 General .11
6.2.2 Apparatus and component temperature .11
6.2.3 Standardised dust immersion temperature test. .11
6.2.4 Wiring within apparatus .12
6.2.5 Printed circuit wiring .12
6.2.6 12
6.3 Facilities for connection of external circuits .12
6.3.1 Terminals .12
6.3.2 Plugs and sockets .12
6.3.3 Determination of maximum external inductance to resistance ratio
(Lo/Ro) for resistance limited power source .12
6.3.4 Permanently connected cables .12
6.4 Separation distances.12
6.5 Protection against polarity reversal.12
6.6 Earth conductors, connections and terminals.12
6.7 Encapsulation used for exclusion of potentially explosive atmosphere.12
7 Components on which intrinsic safety depends.12
7.1 Rating of components.12
7.2 Connectors for internal connections, plug-in cards and components.13
7.3 Fuses .13
7.4 Primary and secondary cells and batteries .13
7.5 Semiconductors.13
7.6 Failure of components and connections.13
7.7 Piezo-electric devices.13
8 Infallible components, infallible assemblies of components and infallible
connections .13
9 Diode safety barriers .13
10 Type verifications, assessments and type tests .13
10.1 Spark ignition assessment.13
10.2 Temperature tests .13
10.3 Voltage tests .13
10.4 Small component ignition test.13
10.5 Determination of parameters of loosely specified components.13
10.6 Tests for cells and batteries .14
10.7 Mechanical test .14
10.7.1 Casting compound.14
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10.7.2 Partitions .14
10.8 Tests for apparatus containing piezoelectric devices .14
10.9 Type tests for diode safety barriers and safety shunts .14
10.10 Cable pull test .14
11 Routine verifications and tests.15
12 Marking .15
12.1 General .15
12.2 Marking of connection facilities.15
13 Documentation .16
Annex A.17
Annex B of IEC 60079-11:1999.17
Annex C of IEC 60079-11. .18
Annex D of IEC 60079-11. .19
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61241-11 Ed.1 /CDV IEC – -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
ELECTRICAL APPARATUS FOR USE IN THE
PRESENCE OF COMBUSTIBLE DUST -
Part 11: Protection by intrinsic safety ‘iD’
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61241-11 (DRAFT) has been prepared by subcommittee 31H - WG3: Intrinsically-safe
apparatus, of IEC technical committee 31: Electrical apparatus for use in the presence of combustible dusts.
th
This edition is an initial draft for comment. The text is based on the 4 edition of IEC 60079-11 1999.
This International Standard is to be read in conjunction with IEC61241-0:200X Electrical apparatus for use in
combustible dust - Part 0: General Requirements
Annexes A & C are normative
Annex B is informative
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61241-11 Ed.1 /CDV IEC – -
IEC 61241 consists of the following parts under the general title:
Electrical apparatus for use in the presence of combustible dust:
• Part 0: Electrical Apparatus - General Requirements
• Part 1: Protection by enclosures ‘tD’;
• Part 2: Protection by pressurization ‘pD’
• Part 10: Classification of areas where combustible dusts are or may be present
• Part 11: Protection by intrinsic safety ‘iD’
• Part 14: Selection and installation
1)
• Part 17: Inspection and maintenance
1)
• Part 18: Protection by encapsulation ‘mD’
• Part 20: Test Methods
• Part 20-1: Methods for determining the minimum ignition temperatures of dust
• Part 20-2: Method for determining the electrical resistivity of dust in layers
• Part 20-3: Method for determining minimum ignition energy of dust/air mixtures
1) Under consideration.
IMPORTANT NOTE:
All references in this document, to the IEC 61241 series, follows the proposed
renumbering of the dust standards agreed by SC31H and TC31 It may be
necessary to alter these numbers if the standards are not yet published
REFERENCE TABLE
Anticipated
Number of Proposed New
Subject Date of
Current Standard Number
Change
IEC 61241-0 General Requirements 2003
IEC 61241-1-1
IEC 61241-1 Protection by enclosure 2003
IEC 61241-1-2 IEC 61241-14 Selection & installation 2003
IEC 61241-2-1 IEC 61241-20-1 Test Methods 2005
IEC 61241-2-2 IEC 61241-20-2 Test Methods 2005
IEC 61241-2-3 IEC 61241-20-3 Test Methods 2005
IEC 61241-3 IEC 61241-10 Classification 2003
IEC 61241-4 IEC 61241-2 Protection by pressurization 2005
IEC 61241-11 Protection by intrinsic safety 2002
IEC 61241-18 Protection by encapsulation 2004
IEC 61241-17 Inspection & Maintenance ?
IEC 61241-19 Repair & Overhaul ?
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INTRODUCTION
Many dusts which are generated, processed, handled and stored, are combustible. When
ignited they can burn rapidly and with considerable explosive force if mixed with air in the
appropriate proportions. It is often necessary to use electrical apparatus in locations where
such combustible materials are present, and suitable precautions must therefore be taken to
ensure that all such apparatus is adequately protected so as to reduce the likelihood of
ignition of the external explosive atmosphere. In electrical apparatus, potential ignition
sources include electrical arcs and sparks, hot surfaces, and frictional sparks.
Areas where dusts, flyings and fibres in air occur in dangerous quantities are classified as
hazardous and are divided into 3 Zones according to the level of risk.
Generally, electrical safety is ensured by the implementation of one of two considerations, i.e.
that electrical apparatus be located where reasonably practicable outside hazardous areas
and that electrical apparatus be designed, installed and maintained in accordance with
measures recommended for the area in which the apparatus is located.
Combustible dust can be ignited by electrical apparatus in several main ways:
• by surfaces of the apparatus that are above the minimum ignition temperature of the
dust concerned. The temperature at which a type of dust ignites is a function of the
properties of the dust, whether the dust is in a cloud or layer, the thickness of the layer
and the geometry of the heat source;
• by arcing or sparking of electrical parts such as switches, contacts, commutators,
brushes, or the like;
• by discharge of an accumulated electrostatic charge;
• by radiated energy (e.g. electromagnetic radiation);
• by mechanical sparking or frictional sparking or heating associated with the apparatus.
In order to avoid ignition hazards it is necessary that:
• the temperature of surfaces, on which dust can be deposited, or which would be in
contact with a dust cloud, is kept below the temperature limitation specified in this
standard;
• any electrical sparking parts, or parts having a temperature above the temperature
limit specified in IEC 61241 Part 14
− are contained in an enclosure which adequately prevents the ingress of dust, or
− the energy of electrical circuits is limited so as to avoid arcs, sparks or
temperatures capable to ignite combustible dust;
• any other ignition sources are avoided.
Several techniques are available for the explosion-protection of electrical apparatus in
hazardous areas. This Standard describes the safety features of type of explosion-protection
technique and specifies the requirements to be adopted. It is most important that the correct
selection and installation procedures be followed to ensure the safe use of electrical
apparatus in hazardous areas.
Compliance with this standard will only provide the required level of safety if the electrical
apparatus is operated within its rating and is installed and maintained according to the
relevant codes of practice or requirements, for example in respect of protection against over-
currents, internal short-circuits, and other electrical faults. In particular, it is essential that the
severity and duration of an internal or external fault be limited to values that can be sustained
by the electrical apparatus without damage, for example, installed in a system designed in
accordance with the principles of IEC 60079-25 and installed in accordance with IEC 61241-
14.
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The following principles should be followed:
• The electronic circuits must fulfil Group IIB requirements according to 60079-11 to
avoid spark ignition
• IP 6x or encapsulation is normally required to ensure that creepage and clearance
distances are not compromised by dusts. Therefore the importance and the durability
of the integrity of the enclosure or encapsulation are much higher than required by
IEC 60079-11.
• Power limitation for apparatus or parts of apparatus not protected by an enclosure or
encapsulation (e. g. uninsulated sensor) to avoid ignition of a dust layer by power
dissipation directly into the dust (power matching by conductive dusts) and to avoid
thermal ignition at the surface of components.
• Limitation of the temperature of all exposed surfaces of all apparatus or parts of
apparatus exceeding the power limitation limits in accordance to 61241-0. The surface
can be the
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