SIST EN 61241-18:2005
(Main)Electrical apparatus for use in the presence of combustible dust -- Part 18: Protection by encapsulation mD
Electrical apparatus for use in the presence of combustible dust -- Part 18: Protection by encapsulation mD
Applicable to electrical apparatus protected by encapsulation type of protection mD and surface temperature limitation for use in areas where combustible dust may be present in quantities which could lead to a fire or explosion hazard. Specifies requirements for design, construction and testing of electrical apparatus, parts of electrical apparatus and Ex components where the rated voltage does not exceed 10 kV. The application of electrical apparatus in atmospheres which may contain explosive gas as well as combustible dust, whether simultaneously or separately, requires additional protective measures.
Elektrische Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub -- Teil 1: Schutz durch Vergusskapselung mD
Matériels électriques pour utilisation en présence de poussières combustibles -- Partie 18: Protection par encapsulage mD
S'applique aux matériels électriques protégés par encapsulage de type mD et par limitation de la température de surface en vue d'une utilisation dans des zones de présence de poussière combustible en quantités pouvant entraîner des risques d'incendie ou d'explosion. Spécifie les exigences de conception, de construction et d'essais du matériel électrique, des pièces du matériel électrique et des composants Ex pour lesquels la tension assignée ne dépasse pas 10 kV. L'utilisation du matériel électrique dans des atmosphères qui peuvent contenir du gaz explosif et de la poussière combustible soit simultanément soit séparément requiert des mesures de protection supplémentaires.
Električne naprave za uporabo v prisotnosti gorljivega prahu - 18. del: Zaščita zalivanje z zalivno maso "mD" (IEC 61241-18:2004)
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Standards Content (Sample)
SLOVENSKI SIST EN 61241-18:2005
STANDARD
april 2005
Električne naprave za uporabo v prisotnosti gorljivega prahu - 18. del: Zaščita
zalivanje z zalivno maso "mD" (IEC 61241-18:2004)
Electrical apparatus for use in the presence of combustible dust – Part 18:
Protection by encapsulation "mD"
ICS 29.260.20 Referenčna številka
SIST EN 61241-18:2005(en)
© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno
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EUROPEAN STANDARD EN 61241-18
NORME EUROPÉENNE
EUROPÄISCHE NORM November 2004
ICS 29.260.20
English version
Electrical apparatus for use in the presence of combustible dust
Part 18: Protection by encapsulation "mD"
(IEC 61241-18:2004)
Matériels électriques pour utilisation en Elektrische Betriebsmittel zur Verwendung
présence de poussières combustibles in Bereichen mit brennbarem Staub
Partie 18: Protection par encapsulage Teil 1: Schutz durch Vergusskapselung
"mD" "mD"
(CEI 61241-18:2004) (IEC 61241-18:2004)
This European Standard was approved by CENELEC on 2004-10-01. 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, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.
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
© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61241-18:2004 E
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EN 61241-18:2004 - 2 -
Foreword
The text of document 31H/176/FDIS, future edition 1 of IEC 61241-18, 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 61241-18 on 2004-10-01.
*)
This standard is to be used 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) 2005-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-10-01
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(s). See Annex ZZ.
Annexes ZA and ZZ have been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61241-18:2004 was approved by CENELEC as a European
Standard without any modification.
__________
*)
In preparation.
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- 3 - EN 61241-18:2004
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 Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60079-7 2001 Electrical apparatus for explosive gas EN 60079-7 2003
atmospheres
Part 7: Increased safety "e"
IEC 60079-11 1999 Part 11: Intrinsic safety "i" - -
1) 2)
IEC 60086-1 - Primary batteries EN 60086-1 2001
Part 1: General
IEC 60127 Series Miniature fuses EN 60127 Series
1) 2)
IEC 60243-1 - Electrical strength of insulating materials - EN 60243-1 1998
Test methods
Part 1: Tests at power frequencies
3)
IEC 60285 1993 Alkaline secondary cells and batteries - EN 60285 1994
Sealed nickel-cadmium cylindrical
rechargeable single cells
1) 2)
IEC 60622 - Secondary cells and batteries containing EN 60622 2003
alkaline or other non-acid electrolytes -
Sealed nickel-cadmium prismatic
rechargeable single cells
IEC 60664-1 1992 Insulation coordination for equipment
within low-voltage systems
Part 1: Principles, requirements and tests
+ A1 2000
+ A2 2002 EN 60664-1 2003
1) 2)
IEC 60691 - Thermal-links - Requirements and EN 60691 2003
application guide
1) 2)
IEC 61150 - Alkaline secondary cells and batteries - EN 61150 1993
Sealed nickel-cadmium rechargeable
monobloc batteries in button cell design
1)
Undated reference.
2)
Valid edition at date of issue.
3)
EN 60285 is superseded by EN 61951-1:2003 which is based on IEC 61951-1:2003.
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EN 61241-18:2004 - 4 -
Publication Year Title EN/HD Year
1)
IEC 61241-0 - Electrical apparatus for use in the - -
presence of combustible dust
Part 0: General requirements
1) 2)
IEC 61241-1 - Electrical apparatus for use in the EN 61241-1 2004
presence of combustible dust
Part 1: Protection by enclosures "tD"
4)
IEC 61241-11 - Part 11: Intrinsically safe apparatus 'iD' - -
5)
IEC 61436 1998 Secondary cells and batteries containing EN 61436 1998
alkaline or other non-acid electrolytes -
Sealed nickel-metal hydride rechargeable
single cells
1) 2)
IEC 61558-2-6 - Safety of power transformers, power EN 61558-2-6 1997
supply units and similar
Part 2-6: Particular requirements for
safety isolating transformers for general
use
1) 2)
IEC 61960-1 - Secondary lithium cells and batteries for EN 61960-1 2001
portable applications
Part 1: Secondary lithium cells
1) 2)
IEC 62326-4-1 - Printed boards EN 62326-4-1 1997
Part 4: Rigid multilayer printed boards
with interlayer connections - Sectional
specification -- Section 1: Capability
Detail Specification - Performance levels
A, B and C
ISO 62 1999 Plastics - Determination of water EN ISO 62 1999
absorption
ANSI/UL 248-1 1995 Standard for low-voltage fuses - -
Part 1: General requirements
ANSI/UL 746B 2000 Polymeric Materials - Long-Term Property - -
Evaluations
4)
To be published.
5)
EN 61436 is superseded to EN 61951-2:2000, which is based on IEC 61951-2:2003.
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- 5 - EN 61241-18:2004
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 all
relevant essential requirements as given in Annex II of the EC Directive 94/9/EC.
Compliance with this standard provides one means of conformity with the specified essential
requirements of the Directive[s] concerned.
WARNING: Other requirements and other EC Directives may be applicable to the products falling
within the scope of this standard.
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NORME CEI
INTERNATIONALE IEC
61241-18
INTERNATIONAL
Première édition
STANDARD
First edition
2004-08
Matériels électriques pour utilisation
en présence de poussières combustibles –
Partie 18:
Protection par encapsulage «mD»
Electrical apparatus for use in the
presence of combustible dust –
Part 18:
Protection by encapsulation "mD"
Numéro de référence
Reference number
CEI/IEC 61241-18:2004
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61241-18” IEC:2004 – 3 –
CONTENTS
FOREWORD .7
INTRODUCTION .13
1 Scope .17
2 Normative references .17
3 Terms and definitions .21
4 General.23
4.1 Temperature classification.23
4.2 Level of protection.23
4.3 Level of protection "maD" .23
4.4 Level of protection "mbD" .23
4.5 Supply specifications.25
5 Requirements for compounds .25
5.1 General .25
5.2 Specification .25
6 Temperatures.25
6.1 General .25
6.2 Temperature limitation.27
6.3 Determination of the limiting temperature values.27
7 Constructional requirements .27
7.1 General .27
7.2 Determination of possible faults.29
7.3 Switching contacts.41
7.4 External connections .41
7.5 Protection of bare live parts .41
7.6 Cells and batteries .41
7.7 Protective devices .47
8 Type tests .49
8.1 Tests on the compound – water absorption test .49
8.2 Tests on the apparatus .49
9 Routine verifications and tests.57
9.1 Visual inspections .57
9.2 Dielectric strength test.57
10 Marking.59
Annex A (informative) Basic requirements for compounds for encapsulation “mD”
apparatus .61
Annex B (normative) Allocation of test samples.63
Annex C (normative) Test procedure during thermal cycling test.65
Figure 1 – Distances between free surface of compound and components or
conductors .33
Figure 2 – Distances between the wall or the free surface of the compound and the
components or conductors.35
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61241-18” IEC:2004 – 5 –
Figure 3 – Distances between the wall or the free surface of the compound and the
components or conductors.37
Figure 4 – Minimum distances for multi-layer printed wiring boards .41
Figure A.1 Basic requirements for compounds for encapsulation “mD” apparatus .61
Figure C.1 – Test procedure during thermal cycling test .65
Table 1 – Distances through the compound.31
Table 2 Thickness of compound between the free surface of the compound and
components or conductors.33
Table 3 – Thickness of the compound between the wall or the free surface of the
compound and the components or conductors.35
Table 4 – Thickness of the compound between the wall or the free surface of the
compound and the components or conductors.37
Table 5 – Minimum distances for multi-layer printed wiring boards.39
Table 6 – Permissible primary cells.43
Table 7 – Permissible secondary cells .43
Table 8 – Test pressure.57
Table B.1 Allocation of test samples.63
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61241-18” IEC:2004 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL APPARATUS FOR USE IN THE
PRESENCE OF COMBUSTIBLE DUST –
Part 18: Protection by encapsulation “mD”
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 61241-18 has been prepared by subcommittee 31H: Apparatus for
use in the presence of combustible dust, 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/176/FDIS 31H/180/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.
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61241-18” IEC:2004 – 9 –
This standard 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: Type of protection ‘pD’
Part 10: Classification of areas where combustible dusts are or may be present
1
Part 11: Protection by intrinsic safety ‘iD’
Part 14: Selection and installation
Part 17: Inspection and maintenance of electrical installations in hazardous areas (other
1
than mines)
Part 18: Protection by encapsulation ‘mD’
1
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 follows 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.
___________
1
To be published.
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61241-18” IEC:2004 – 11 –
REFERENCE TABLE
Anticipated
New number
Standard Subject date of
assigned
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
IEC 61241-19 Repair and overhaul 2006
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61241-18” IEC:2004 – 13 –
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 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 (for example, 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.
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.
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61241-18” IEC:2004 – 15 –
Several techniques are available for the explosion protection of electrical apparatus in
hazardous areas. This standard describes the safety features of these types of explosion-
protection techniques and specifies the installation procedures 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.
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61241-18” IEC:2004 – 17 –
ELECTRICAL APPARATUS FOR USE IN THE
PRESENCE OF COMBUSTIBLE DUST –
Part 18: Protection by encapsulation “mD”
1 Scope
This standard is to be read in conjunction with IEC 61241-0, the requirements of which apply
to electrical apparatus protected by encapsulation and surface temperature limitation unless
specifically excluded.
This part of IEC 61241 is applicable to electrical apparatus protected by encapsulation type
of protection “mD" and surface temperature limitation for use in areas where combustible
dust may be present in quantities which could lead to a fire or explosion hazard. It specifies
requirements for design, construction and testing of electrical apparatus, parts of electrical
apparatus and Ex components where the rated voltage does not exceed 10 kV.
NOTE 1 The actual working voltage may exceed the value given above by up to 10 %.
NOTE 2 IEC 61241-14 (“Electrical apparatus for use in the presence of combustible dust – Part 14: Selection and
installation”) gives guidance on the selection and installation of the apparatus. Apparatus within the scope of this
standard may also be subjected to additional requirements in other standards – for example, IEC 60079-0
(“Electrical apparatus for explosive gas atmospheres - Part 0: General requirements”).
The application of electrical apparatus in atmospheres which may contain explosive gas as
well as combustible dust, whether simultaneously or separately, requires additional protective
measures.
This standard does not apply to dusts of explosives which do not require atmospheric oxygen
for combustion, or to pyrophoric substances.
This standard is not applicable to electrical apparatus intended for use in underground parts
of mines as well as those parts of surface installations of such mines endangered by
firedamp and/or combustible dust. This standard does not take account of any risk due to an
emission of flammable or toxic gas from the dust.
This standard does not include other types of protection and is only applicable to protection
by encapsulation.
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 60079-7:2001, Electrical apparatus for explosive gas atmospheres – Part 7: Increased
safety "e“
IEC 60079-11:1999, Electrical apparatus for explosive gas atmospheres – Part 11: Intrinsic
safety "i“
IEC 60086-1, Primary batteries – Part 1: General
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61241-18” IEC:2004 – 19 –
IEC 60127 (all parts), Miniature fuses
IEC 60243–1, Electrical strength of insulating materials – Test methods – Part 1: Tests at
power frequencies
IEC 60285, Alkaline secondary cells and batteries – Sealed nickel-cadmium cylindrical
2
rechargeable single cells
IEC 60622, Secondary cells and batteries containing alkaline or other non-acid electrolytes –
Sealed nickel-cadmium prismatic rechargeable single cells
IEC 60664–1:1992, Insulation co-ordination for equipment within low-voltage systems – Part
1: Principles, requirements and tests
Amendment 1 (2000)
Amendment 2 (2002)
IEC 60691, Thermal links – Requirements and application guide
IEC 61150, Alkaline secondary cells and batteries – Sealed nickel cadmium rechargeable
monobloc batteries in button cell design
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”
IEC 61241-11:, Electrical apparatus for use in the presence of combustible dust – Part 11:
3
Protection by intrinsic safety “iD”
IEC 61436, Secondary cells and batteries containing alkaline or other non-acid electrolytes –
4
Sealed nickel-metal hydride rechargeable single cells
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2:
Particular requirements for safety isolation transformers for general use
IEC 61960-1, Secondary lithium cells and batteries for portable applications – Part 1:
Secondary lithium cells
IEC 62326-4-1, Printed boards – Part 4: Rigid multilayer printed boards with interlayer
connections – Sectional specification – Section 1: Capability detail specification –
Performance levels A, B and C
ISO 62, Plastics – Determination of water absorption
...
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