EN 61241-11:2006

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.

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.
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
Droits de reproduction réservés

Copyright - all rights reserved Aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch
Web: www.iec.ch CODE PRIX PRICE CODE Q Commission Electrotechnique InternationaleInternational Electrotechnical Commission

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 s
...