HD 384.4.43 S2:2001
(Main)Electrical installations of buildings - Part 4: Protection for safety - Chapter 43: Protection against overcurrent
Electrical installations of buildings - Part 4: Protection for safety - Chapter 43: Protection against overcurrent
Sets out general rules for protection of live conductors against overload and short circuit. Specifies the features of various protective devices and necessary coordination between conductors and overload protective devices. Formula for calculation of time in which a given short-circuit current will raise a conductor from the highest admissible temperature in normal duty to its limit temperature. Enumerates requirements for coordination of overload and short-circuit protection. Note: For details of -low-voltage circuit breakers, see EN 60974-2 -low-voltage fuses, see EN 60269 -for coordination of low-voltage direct-online (full voltage) motor starters with short-circuit protective devices, see EN 60974-1 -for current-carrying capacities of conductors for electrical installations of buildings, see IEC 60364-5-523.
Elektrische Anlagen von Gebäuden - Teil 4: Schutzmaßnahmen - Kapitel 43: Schutz gegen Überstrom
Installations électriques des bâtiments - Partie 4: Protection pour assurer la sécurité - Châpitre 43: Protection contre les surintensités
Donne les règles générales pour la protection des conducteurs actifs contre les surcharges et les courts-circuits. Spécifie les caractéristiques de divers dispositifs de protection et la coordination nécessaire entre les conducteurs et les dispositifs de protection contre les surcharges. Formule le calcul de la durée pendant laquelle un courant de court-circuit donné élèvera la température d'un conducteur de sa valeur la plus élevée admissible en service normal à sa valeur limite. Enumère les règles de coordination de la protection contre les surcharges et contre les courts-circuits. Note: - Pour plus de détails, - sur les disjoncteurs à basse tension, voir la EN 60974-2 - sur les coupe-circuit à fusibles à basse tension, voir la EN 60269 - sur la coordination des démarreurs de moteurs à basse tension directs (sous pleine tension) avec dispositifs de protection contre les courts-circuits, voir la EN 60974-1 - sur les intensités admissibles des conducteurs pour les installations électriques des bâtiments, voir IEC 60364-5-523.
Električne inštalacije zgradb – 4. del: Zaščitni ukrepi – 43. poglavje: Zaščita pred nadtoki (IEC 60364-4-43:1977 + A1:1997, spremenjen)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2003
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Electrical installations of buildings -- Part 4: Protection for safety -- Chapter 43:
Protection against overcurrent
Elektrische Anlagen von Gebuden -- Teil 4: Schutzmanahmen -- Kapitel 43: Schutz
gegen berstrom
Installations lectriques des btiments -- Partie 4: Protection pour assurer la scurit --
Chpitre 43: Protection contre les surintensits
Ta slovenski standard je istoveten z: HD 384.4.43 S2:2001
ICS:
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
HARMONIZATION DOCUMENT HD 384.4.43 S2
DOCUMENT D'HARMONISATION
HARMONISIERUNGSDOKUMENT November 2001
ICS 29.120.50; 91.140.50 Supersedes HD 384.4.43 S1:1980
English version
Electrical installations of buildings
Part 4: Protection for safety
Chapter 43: Protection against overcurrent
(IEC 60364-4-43:1977 + A1:1997, modified)
Installations électriques des bâtiments Elektrische Anlagen von Gebäuden
Partie 4: Protection pour assurer Teil 4: Schutzmaßnahmen
la sécurité Kapitel 43: Schutz gegen Überstrom
Châpitre 43: Protection contre (IEC 60364-4-43:1977 + A1:1997,
les surintensités modifiziert)
(CEI 60364-4-43:1977 + A1:1997,
modifiée)
This Harmonization Document was approved by CENELEC on 1999-08-01. CENELEC members are
bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
implementation of this Harmonization Document on a national level.
Up-to-date lists and bibliographical references concerning such national implementation may be obtained on
application to the Central Secretariat or to any CENELEC member.
This Harmonization Document exists in three official versions (English, French, German).
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, 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
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. HD 384.4.43 S2:2001 E
Foreword
The texts of the International Standard IEC 60364-4-43:1977 + amendment 1:1997, prepared by IEC TC 64,
Electrical installations and protection against electric shock, together with the common modifications prepared
by SC 64B, Protection against thermal effects, of Technical Committee CENELEC TC 64, Electrical
installations of buildings, were submitted to the formal vote and were approved by CENELEC as
HD 384.4.43 S2 on 1999-08-01.
The following dates were fixed:
- latest date by which the existence of the HD (doa) 2000-02-01
has to be announced at national level
- latest date by which the HD has to be implemented (dop) 2002-06-01
at national level by publication of a harmonized
national standard or by endorsement
- latest date by which the national standards conflicting (dow) 2002-08-01
with the HD have to be withdrawn
In this Harmonization Document, the common modifications to the International Standard are indicated by a
vertical line in the left margin of the text.
CENELEC common modifications to the International Standard IEC 60364-4-43:1977, for which justifications
(X)
are given in annex I, are marked with a vertical line and the number of the respective justification is indicated in
the lefthand margin of the text.
IEC alterations to IEC 60364-4-43:1977 due to amendment 1:1997 are marked with a wavy line in the lefthand
margin of the text.
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this Harmonization Document, annex ZA is normative and annexes I to IV and ZB are informative.
- 3 - HD 384.4.43 S2:2001
Contents
page
Preface . 4
43 Protection against overcurrent . 5
431 General.5
432 Nature of protective devices.5
433 Protection against overload current .6
434 Protection against short-circuit current .6
435 Co-ordination of overload and short-circuit protection.8
436 Limitation of overcurrent by characteristics of supply.8
Annex I (informative) Justification for CENELEC modifications . 9
Annex II (informative) Explanatory notes . 10
Annex III (informative) Definitions . 12
Annex IV (informative) Chapter 53: Selection and erection of switchgear and controlgear. 13
531 Common requirements.13
533 Devices for protection against overcurrent.13
533.1 General requirements.13
533.2 Selection of devices for protection against overloads .13
533.3 Selection of devices for protection against short-circuits.13
Annex ZA (normative) Normative references to international publications with their
corresponding European publications . 16
Annex ZB (informative) A–deviations . 17
Preface
1 Reference document
The reference document for this Harmonization Document is the International Standard IEC 60364-4-43:1977
and its amendment 1:1997 prepared by IEC TC 64: Electrical installations of buildings.
IEC 60364: Electrical installations of buildings, is a composite publication of a number of Parts, each dealing
with a particular aspect of electrical installation. Part 4 is concerned with protection for safety and within that
Part, chapter 43 specifies measures for protection against overcurrents. Other parts of the publication will deal
with the selection, application and co-ordination of measures for protection against overcurrent, for the
selection and erection of the appropriate electrical equipment and for the verification of installations.
2 Scope
The scope of this Harmonization Document is CENELEC Harmonization Document HD 384.1.
3 CENELEC common modifications
CENELEC common modifications of the Reference Document are numbered and indicated by marginal side-
lining. Justification for the common modifications are stated in annex I.
4 Explanations of certain requirements
Some explanations considered to be useful for interpretation of some requirements of the Reference Document
text are given in annex II.
5 Definitions
Pending the production of an IEC Publication suitable for treatment as a Reference Document, specifications
used for the development of this Harmonization Document are provided for guidance only in annex III.
6 Annex IV: Chapter 53, Switchgear (Protection, isolation and switching)
Sections 531 (Common requirements) and 533 (Devices for protection against overcurrent)
The rules relating to the selection and erection of switchgear are currently being considered by IEC/TC 64. In
the meantime, it has seemed necessary to give the conditions for the selection and erection of protective
devices complying with the rules of chapter 43, based on draft IEC 64(Secretariat)2.
Countries are free to decide whether or not to take account of the indications thus given for the selection and
erection of protective devices.
Chapter 53 will later form the subject of a Harmonization Document.
- 5 - HD 384.4.43 S2:2001
43 Protection against overcurrent
431 General
431.1 Live conductors shall be protected by one or more devices for automatic interruption of the supply
in the event of overload (see section 433) and short-circuit (section 434) except where the overcurrent is limited
in accordance with section 436. Further, protection against overload and against short-circuit shall be co-
ordinated in accordance with section 435.
NOTE 1 Live conductors protected against overload in accordance with section 433 are considered to be protected also against
faults likely to cause overcurrent of a magnitude similar to overload currents.
NOTE 2 For conditions of application, see HD 384.4.473.
NOTE 3 The protection of flexible cables in fixed installations is included in these rules. Flexible cables connecting equipment by
plugs and socket-outlet to fixed installations are not necessarily protected against overload; the protection of such cables against short-
(1)
circuits is under consideration.
432 Nature of protective devices
The protective devices shall be chosen from among those indicated by clauses 432.1 to 432.3.
432.1 Devices ensuring protection against both overload current and short-circuit current
These protective devices shall be capable of breaking any overcurrent up to and including the prospective
short-circuit current at the point where the device is installed. They shall satisfy the requirements of section 433
and subclause 434.3.1. Such protective devices may be
*)
- circuit breaker incorporating overload release ,
- circuit breakers in conjunction with fuses,
**)
- fuses having fuse-links with gG characteristics .
NOTE 1 The fuse comprises all the parts that form the complete protective device.
NOTE 2 The use of a protective device having a breaking capacity below the value of the protective short-circuit current at its place
of installation is subject to the requirement of subclause 434.3.1.
NOTE 3 This subclause does not preclude the use of protective devices having other characteristics providing that the requirements
of 433.2 are met.
432.2 Devices ensuring protection against overload current only
These are generally inverse-time-lag protective device whose interrupting capacity may be below the value of
the prospective short-circuit current at the point where the device is installed. They shall satisfy the requirement
of section 433.
432.3 Devices ensuring protection against short-circuit current only
These devices may be installed where overload protection is achieved by other means or where HD 384.4.473
allows overload protection to be dispensed with. The device shall be capable of breaking short-circuit currents
up to and including the prospective short-circuit current. They shall satisfy the requirements of section 434.
Such devices may be
*)
- circuit breakers with short-circuit releases ,
**)
- fuses .
432.4 Protection of conductors in parallel
Methods of protecting conductors in parallel against overload current and short-circuit current are given in
chapter 47.
432.5 Characteristics of protective devices
The time/current characteristics of overcurrent protective devices shall comply with those specified in
(2) Harmonization Document HD …(documents under consideration, based on IEC 60157-1, 60157-2, 60269-2,
60269-3 and 60292-1).
*)
IEC 60898, IEC 60947-2 and IEC 61009.
**)
IEC 60269-1, IEC 60269-2 and IEC 60269-3.
NOTE The use of other devices is not excluded provided that their time/current characteristics provide an equivalent level of
protection to that specified in this clause.
433 Protection against overload current
433.1 General
Protective devices shall be provided to break any overload current flowing in the circuit conductors before such
a current could cause a temperature rise detrimental to insulation, joints, terminations or surroundings of the
conductors.
433.2 Co-ordination between conductors and protective devices
The operating characteristics of a device protecting a cable against overload shall satisfy the following conditions:
1) I � I � I
b n z
2) I � 1,45 I
2 z
I Design current of the circuit,
b
I Continuous current carrying capacity of the cable (see section 523),
z
I Nominal current of the protective device.
n
NOTE For adjustable protective devices, the nominal current I is the current setting selected.
n
I Current ensuring effective operation in conventional time of the protective device and generally given in the
product standard.
NOTE Protection in accordance with this clause does not ensure complete protection in certain cases, for example against sustained
overcurrents less than I , nor will it necessarily result in the most economic solution. Therefore, it is assumed that the circuit is so
designed that small overloads of long duration will not frequently occur.
433.4 Protection of ring final circuits
(3)
(under consideration)
434 Protection against short-circuit current
NOTE This document only considers the case of short-circuit anticipated between conductors belonging to the same circuit.
(4)
434.1 General
Protective devices shall be provided to break any short-circuit current flowing in the conductors before a current
could cause danger due to thermal and mechanical effects produced in conductors and connections.
434.2 Determination of prospective short-circuit current
The prospective short-circuit current at every relevant point of the installation shall be determined. This may be
done either
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