EN 50394-1:2004

SLOVENSKI SIST EN 50394-1:2004

STANDARD
junij 2004
Električne naprave za potencialno eksplozivne atmosfere - Skupina I -
Lastnovarni sistemi - 1. del: Konstruiranje in preskušanje
Electrical apparatus for potentially explosive atmospheres - Group I - Intrinsically
safe systems - Part 1: Construction and testing
ICS 29.260.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 50394-1
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2004
ICS 29.260.20
English version
Electrical apparatus for potentially explosive atmospheres –
Group I – Intrinsically safe systems
Part 1: Construction and testing

Matériels électriques pour atmosphères Elektrische Betriebsmittel für
explosibles – explosionsgefährdete Bereiche –
Système de sécurité intrinsèque du Gruppe I: Eigensichere Systeme
groupe I Teil 1: Konstruktion und Prüfung
Partie 1: Construction et essais

This European Standard was approved by CENELEC on 2003-10-01. 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 50394-1:2004 E
Foreword
This European Standard was prepared jointly by a mining working group, convened under SC 31-3,
Intrinsically safe apparatus and systems "i", of Technical Committee CENELEC TC 31, Electrical apparatus
for explosive atmospheres.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC
as EN 50394-1 on 2003-10-01.
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) 2004-10-01
- latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-10-01
This European Standard was prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association to set down requirements for the design and construction of
equipment in support of the essential safety and health requirements described in the European Directive
94/9/EC "Equipment and protective systems intended for use in potentially explosive atmospheres".

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Contents
Introduction.4
1 Scope.5
2 Normative references.5
3 Definitions.5
4 Categories of intrinsically safe electrical systems (in accordance with EN 50014) .7
5 Interconnecting wiring/cables used in an intrinsically safe electrical system .7
6 Accessories for intrinsically safe electrical systems .8
7 Type tests and assessment.8
8 Marking of intrinsically safe electrical systems.10
9 Descriptive system document.11
10 Instructions.11

Annex A (normative) Requirements for cables .12
Annex B (informative) Typical descriptive system drawing.1
Annex C (normative) Assessment of a simple intrinsically safe system.14
Annex D (normative) Assessment of circuits with more than one linear source of power.16
Annex E (normative) Trapezoidal power supplies.19
Annex F (normative) Non-linear power supplies .20
Annex G (normative) Verification of inductive parameters .21

Introduction
When the European Directive 94/9/EC came into force on 1 March 1996, the requirements relating to
intrinsically safe electrical systems were identified as requiring revision.
The EU Commission issued the following interpretation, following a request from CENELEC TC 31:
"a) intrinsically safe systems are not protective systems as defined in Article 1(3b) of the directive. They
can be equipment, as defined in Article 1(3a), or components, as defined in Article 1(3c) and are in
such cases within the scope of the directive;
b) intrinsically safe systems have to undergo the relevant conformity assessment procedures of the
directive, if they are placed on the market as a complete system and, therefore, to be considered as
equipment or components;
c) in case an intrinsically safe system comprises several separate products, which are designed to be
assembled by the user, each single product, which is within the scope of the directive and placed on
the market separately, has to undergo the relevant conformity assessment procedure of the
directive;
d) the resulting system has to be seen as an installation and it is, as such, not subject to the
procedures and requirements of the directive. This does not exclude that there might be national
regulations related to the use of intrinsically safe systems, which have to be applied. In this context
the use of EN 50039 could be useful.”
As a result of the above interpretation, CENELEC SC 31-3 decided to produce a revised version of
EN 50039 with separate parts for mining (Group I) and non-mining industries (Group II). Accordingly, this
standard is the mining industry document dealing with the construction and testing of Group I intrinsically
safe systems.
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1 Scope
1.1 This European Standard contains the requirements for construction and testing of Group I
intrinsically safe electrical systems intended for use, as a whole or in part, in atmospheres susceptible to
firedamp.
1.2 This European Standard supplements EN 50020, the requirements of which apply to electrical
apparatus used in intrinsically safe electrical systems.
It is intended to apply to
− systems placed on the market by a manufacturer or their authorised representative, or
− systems assembled by the user, using products separately conforming with EN 50020.
NOTE If the user intends to assemble a system using a product not conforming with EN 50020, then the user assumes the
responsibilities of the system manufacturer and needs to follow the conformity assessment procedure.
1.3 This European Standard does not deal with the selection of suitable equipment, or the installation of
intrinsically safe electrical apparatus, associated electrical apparatus, to form an intrinsically safe electrical
system.
NOTE National Regulations may impose additional requirements for the selection, installation and use of intrinsically safe systems
in mines.
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.
Publication Title
EN 50014 Electrical apparatus for potentially explosive atmospheres - General
requirements
EN 50020 Electrical apparatus for potentially explosive atmospheres - Intrinsic safety ‘i’
EN 50303 Group I Category M1 equipment intended to remain functional in atmospheres
endangered by firedamp and/or coal dust
3 Definitions
For the purpose of this European Standard, the following definitions apply. They supplement the
definitions, which are given in EN 50014, EN 50020, and EN 50303.
3.1
intrinsically safe electrical system
interconnected items of electrical apparatus, described in a descriptive system document, in which the
circuits or parts of circuits intended to be used in potentially explosive atmospheres, are intrinsically safe
circuits
3.2
conformity-assessed intrinsically safe electrical system
a complete system placed on the market, conforming with 3.1 which has undergone the relevant
conformity assessment procedures and complies with the requirements of this standard

3.3
user constructed intrinsically safe electrical system
a system conforming with 3.1 and assembled by the user comprising products separately conforming to
EN 50020 (which may consist of associated apparatus, intrinsically safe apparatus and/or simple
apparatus and interconnecting wiring supplied from one or more linear power supplies or a power supply
with trapezoidal/non-linear output characteristic) for which an assessment report has been issued
confirming that the complete electrical system complies with this standard
3.4
descriptive system document
a document prepared by the system designer in which the items of electrical apparatus, their electrical
parameters and the parameters for the interconnecting wiring are specified
NOTE The term “system designer” is intended to describe the person, who is responsible for the intrinsic safety of the system.
3.5
equipment Group I category M1 in accordance with EN 50014
equipment designed and, where necessary, equipped with additional special means to be capable of
functioning in conformity with the operational parameters established by the manufacturer and ensuring a
very high level of protection. Equipment in this category is 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. Equipment in this category is intended to remain functional, even in the event of rare incidents
relating to equipment, with an explosive atmosphere present, and is characterised by means of protection
such that
a) either, in the event of failure of one means of protection, at least an independent second
means provides the requisite level of protection, or
b) the requisite level of protection is assured in the event of two faults occurring independently
of each other.
NOTE At the present time, only “level of protection ‘ia’ ”, meets the requirement of (b) above.
3.6
equipment Group I category M2 in accordance with EN 50014
equipment designed to be capable of functioning in conformity with the operational parameters
established by the manufacturer and ensuring a high level of protection. Equipment in this category is
intended for use in underground parts of mines as well as those parts of surface installations of such
mines likely to be endangered by firedamp and/or combustible dust. This equipment is intended to be de-
energised in the event of an explosive atmosphere. The means of protection relating to equipment in this
category assure the requisite level of protection during normal operation and also in the case of more
severe operating conditions, in particular those arising from rough handling and changing environmental
conditions
NOTE The definitions in 3.5 and 3.6 above are an extract of the definitions in EN 50014.
3.7
accessories
passive components such as terminal boxes, junction boxes, plugs, sockets, and switches
3.8
linear power supply
a power source from which the available output current is determined by a resistor. The output voltage
decreases linearly as the output current increases
3.9
power supply with trapezoidal output characteristics
a power source from which the available output current is determined by a resistor. The output voltage is
controlled by the addition of a zener diode clamp on the output terminals (see Annex E for more detail)

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3.10
non-linear power supply
a power source where the output voltage and output current have a non-linear relationship. For example
a supply with a constant voltage output up to constant current limit controlled by semiconductors
3.11
maximum cable capacitance (C )
c
maximum capacitance of the interconnecting cable that can be connected into an intrinsically safe circuit
without invalidating intrinsic safety
3.12
maximum cable inductance (L )
c
maximum inductance of the interconnecting cable that can be connected into an intrinsically safe circuit
without invalidating intrinsic safety
3.13
maximum cable inductance to resistance ratio (L /R )
c c
maximum value of the ratio inductance (L ) to resistance (R ) of the interconnecting cable that can be
c c
connected into an intrinsically safe circuit without invalidating intrinsic safety
4 Categories of intrinsically safe electrical systems (in accordance with EN 50014)
Each part of an intrinsically safe electrical system shall meet the requirements for either category M1 or
M2,
...