Railway applications - Electric equipment for rolling stock - Part 5: Electrotechnical components - Rules for HV fuses

The purpose of NEN-EN-IEC 60077-5 is to give additional or amended rules for high voltage (HV) fuses as a supplement to those given by IEC 60077-2. The high voltage fuses concerned are those connected into power and/or auxiliary circuits. The nominal voltage of these circuits lies between 600 V DC and 3 000 V DC, according to IEC 60850. These fuses can also be used in auxiliary AC circuits up to a nominal voltage of 1500 V. This document together with IEC 60077-2 states specifically: a) the characteristics of the fuses; b) the service conditions with which the fuses comply with reference to: - operation and behaviour in normal service; - operation and behaviour in case of short circuit; - dielectric properties. c) the tests intended for confirming the compliance of the fuse with the characteristics under the service conditions and the methods adopted for these tests; d) the information marked on, or given with, the fuse. This document does not cover parallel connection of fuses. During preparation of this document, IEC 60269-1 and IEC 60282-1 have been considered and their requirements have been kept as far as possible. This document makes reference to the general rules for electrotechnical components given in IEC 60077-2, but for general conditions reference is made directly to IEC 60077-1.

Bahnanwendungen - Elektrische Betriebsmittel auf Fahrzeugen - Teil 5: Elektrotechnische Bauteile - Regeln für Hochspannungssicherungen

Applications ferroviaires - Equipements électriques du matériel roulant - Partie 5: Composants électrotechniques - Règles pour les fusibles à haute tension

IEC 60077-5:2019 est disponible sous forme de IEC 60077-5:2019 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 60077-5:2019 fournir des règles complémentaires ou amendées pour les fusibles à haute tension, en plus de celles données dans l'IEC 60077-2. Les fusibles à haute tension concernés sont connectés dans les circuits de puissance et/ou auxiliaires. La tension nominale de ces circuits est située entre 600 V CC et 3 000 V CC, conformément à l'IEC 60850. Ces fusibles peuvent également être utilisés dans des circuits auxiliaires à courant alternatif jusqu'à une tension nominale de 1 500 V. En complément de l'IEC 60077-2, le présent document précise particulièrement: a) les caractéristiques des fusibles; b) les conditions de service que les fusibles supportent du point de vue: - du fonctionnement et du comportement en service normal; - du fonctionnement et du comportement en cas de court-circuit; - des propriétés diélectriques. c) les essais destinés à vérifier la conformité du fusible avec les caractéristiques dans les conditions de service ainsi que les méthodes à adopter pour ces essais; d) les informations données avec ou marquées sur le fusible. Cette deuxième édition annule et remplace la première édition, parue en 2003. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) révision de la méthode d'essai des conditions d'essai III pour la vérification du pouvoir de coupure.

Železniške naprave - Električna oprema za vozna sredstva - 5. del: Elektrotehnične komponente - Pravila za visokonapetostne varovalke

General Information

Status
Published
Publication Date
08-Jun-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Mar-2020
Due Date
17-May-2020
Completion Date
09-Jun-2020

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SLOVENSKI STANDARD
SIST EN IEC 60077-5:2020
01-julij-2020
Nadomešča:
SIST EN 60077-5:2004

Železniške naprave - Električna oprema za vozna sredstva - 5. del: Elektrotehnične

komponente - Pravila za visokonapetostne varovalke

Railway applications - Electric equipment for rolling stock - Part 5: Electrotechnical

components - Rules for HV fuses

Applications ferroviaires - Equipements électriques du matériel roulant - Partie 5:

Composants électrotechniques - Règles pour les fusibles à haute tension
Ta slovenski standard je istoveten z: EN IEC 60077-5:2019
ICS:
29.120.50 Varovalke in druga Fuses and other overcurrent
nadtokovna zaščita protection devices
29.280 Električna vlečna oprema Electric traction equipment
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
SIST EN IEC 60077-5:2020 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN IEC 60077-5:2020
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SIST EN IEC 60077-5:2020
EUROPEAN STANDARD EN IEC 60077-5
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2019
ICS 45.060 Supersedes EN 60077-5:2003 and all of its amendments
and corrigenda (if any)
English Version
Railway applications - Electric equipment for rolling stock - Part
5: Electrotechnical components - Rules for HV fuses
(IEC 60077-5:2019)

Applications ferroviaires - Équipements électriques du Bahnanwendungen - Elektrische Betriebsmittel auf

matériel roulant - Partie 5: Composants électrotechniques - Fahrzeugen - Teil 5: Elektrotechnische Bauteile - Regeln für

Règles pour les fusibles à haute tension Hochspannungssicherungen
(IEC 60077-5:2019) (IEC 60077-5:2019)

This European Standard was approved by CENELEC on 2019-12-04. 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 CEN-CENELEC

Management Centre 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 CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the

Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 60077-5:2019 E
---------------------- Page: 3 ----------------------
SIST EN IEC 60077-5:2020
EN IEC 60077-5:2019 (E)
European foreword

The text of document 9/2539/FDIS, future edition 2 of IEC 60077-5, prepared by IEC/TC 9 "Electrical

equipment and systems for railways" was submitted to the IEC-CENELEC parallel vote and approved

by CENELEC as EN IEC 60077-5:2019.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2020-09-04

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2022-12-04

document have to be withdrawn

This document supersedes EN 60077-5:2003 and all of its amendments and corrigenda (if any).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 60077-5:2019 was approved by CENELEC as a European

Standard without any modification.
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SIST EN IEC 60077-5:2020
EN IEC 60077-5:2019 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60077-1 2017 Railway applications - Electric equipment EN 60077-1 2017
for rolling stock - Part 1: General service
conditions and general rules
IEC 60077-2 2017 Railway applications - Electric equipment EN 60077-2 2017
for rolling stock - Part 2: Electrotechnical
components - General rules
IEC 60269-1 2006 Low-voltage fuses - Part 1: General EN 60269-1 2007
requirements
+ A1 2009 + A1 2009
+ A2 2014 + A2 2014
IEC 60282-1 2009 High-voltage fuses - Part 1: Current-limiting EN 60282-1 2009
fuses
+ A1 2014 + A1 2014
IEC 61373 - Railway applications - Rolling stock EN 61373 -
equipment - Shock and vibration tests
ISO 3 - Preferred numbers - Series of preferred - -
numbers
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SIST EN IEC 60077-5:2020
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SIST EN IEC 60077-5:2020
IEC 60077-5
Edition 2.0 2019-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Electric equipment for rolling stock –
Part 5: Electrotechnical components – Rules for HV fuses
Applications ferroviaires – Équipements électriques du matériel roulant –
Partie 5: Composants électrotechniques – Règles pour les fusibles
à haute tension
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 45.060.01 ISBN 978-2-8322-7509-2

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 60077-5:2020
– 2 – IEC 60077-5:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms, definitions and abbreviated terms ........................................................................ 7

3.1 Components ........................................................................................................... 7

3.2 Operational characteristics ..................................................................................... 8

3.3 Abbreviated terms ................................................................................................. 10

4 Classification ................................................................................................................. 10

4.1 Breaking range ..................................................................................................... 10

4.2 Utilisation category ............................................................................................... 11

5 Characteristics .............................................................................................................. 11

6 Product information ....................................................................................................... 12

6.1 Documentation ...................................................................................................... 12

6.2 Marking ................................................................................................................. 12

7 Normal service conditions .............................................................................................. 12

8 Constructional and performance requirements ............................................................... 12

8.1 Constructional requirements ................................................................................. 12

8.1.1 General ......................................................................................................... 12

8.1.2 Fuse-link ....................................................................................................... 12

8.1.3 Fuse-base ..................................................................................................... 13

8.1.4 Spring-loaded contacts .................................................................................. 13

8.1.5 External terminals .......................................................................................... 13

8.2 Performance requirements .................................................................................... 13

8.2.1 Operating conditions ...................................................................................... 13

8.2.2 Temperature limits ......................................................................................... 13

8.2.3 Dielectric properties ....................................................................................... 13

8.2.4 Rated voltage ................................................................................................ 13

8.2.5 Rated current of the fuse-link ......................................................................... 14

8.2.6 Rated current of the fuse-base ...................................................................... 14

8.2.7 Breaking capacity .......................................................................................... 14

8.2.8 Time-current characteristics .......................................................................... 14

9 Tests ............................................................................................................................. 14

9.1 Kinds of tests ........................................................................................................ 14

9.1.1 General ......................................................................................................... 14

9.1.2 Type tests ...................................................................................................... 15

9.1.3 Routine tests ................................................................................................. 15

9.1.4 Investigation tests .......................................................................................... 15

9.2 Tests for the verification of constructional requirements ........................................ 15

9.2.1 General ......................................................................................................... 15

9.2.2 Type tests ...................................................................................................... 15

9.2.3 Routine tests ................................................................................................. 16

9.3 Type tests for the verification of performance requirements .................................. 16

9.3.1 Test sequence ............................................................................................... 16

9.3.2 General test conditions .................................................................................. 17

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SIST EN IEC 60077-5:2020
IEC 60077-5:2019 © IEC 2019 – 3 –
9.3.3 Test sequence for the verification of general performance

characteristics ............................................................................................... 18

9.3.4 Description of tests for the fuse-link ............................................................... 18

9.4 Routine tests for the verification of performance requirements .............................. 22

9.4.1 General ......................................................................................................... 22

9.4.2 Resistance measurement .............................................................................. 23

Annex A (normative) Connection diagram for temperature rise tests .................................... 24

Annex B (informative) Comparison between “a” and “g” fuse time current

characteristics ...................................................................................................................... 25

Annex C (informative) Diagram of the test circuit for breaking capacity tests ........................ 26

Annex D (informative) Verification of breaking capacity ........................................................ 27

Bibliography .......................................................................................................................... 29

Figure A.1 – Connection diagram for temperature rise tests .................................................. 24

Figure B.1 – Comparison between “a” and “g” fuse time current characteristics .................... 25

Figure C.1 – Diagram of the test circuit for breaking capacity tests ....................................... 26

Figure D.1 – Test circuit calibration ....................................................................................... 27

Figure D.2 – Breaking operation when the instant of arc initiation is after the peak

value of the current ............................................................................................................... 28

Figure D.3 – Breaking operation when the instant of arc initiation is prior to the peak

value of the current ............................................................................................................... 28

Table 1 – Conventional times for “g” fuse-links ..................................................................... 11

Table 2 – Rated and test voltages for DC fuse-links supplied from the contact line ............... 14

Table 3 – Sequence of tests for the highest rating of a homogeneous series ........................ 16

Table 4 – Sequence of tests for the lowest rating of a homogeneous series .......................... 17

Table 5 – Sequence of tests for the intermediate ratings of a homogeneous series ............... 17

Table 6 – Tolerances on test values ...................................................................................... 18

Table 7 – Parameters for breaking capacity tests of DC fuse-links ........................................ 20

Table 8 – Time constant of the test circuit ............................................................................. 21

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SIST EN IEC 60077-5:2020
– 4 – IEC 60077-5:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
ELECTRIC EQUIPMENT FOR ROLLING STOCK –
Part 5: Electrotechnical components –
Rules for HV fuses
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

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 60077-5 has been prepared by IEC technical committee 9:

Electrical equipment and systems for railways.

This second edition cancels and replaces the first edition, issued in 2003. It constitutes a

technical revision.

This edition includes the following main technical changes with regard to the previous edition:

a) test method of test duty III for verification of breaking capacity is reviewed.

---------------------- Page: 10 ----------------------
SIST EN IEC 60077-5:2020
IEC 60077-5:2019 © IEC 2019 – 5 –
The text of this International Standard is based on the following documents:
FDIS Report on voting
9/2539/FDIS 9/2555/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

This document should be read in conjunction with IEC 60077-1 and IEC 60077-2.

A list of all parts in the IEC 60077 series, published under the general title Railway

applications – Electric equipment for rolling stock, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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SIST EN IEC 60077-5:2020
– 6 – IEC 60077-5:2019 © IEC 2019
RAILWAY APPLICATIONS –
ELECTRIC EQUIPMENT FOR ROLLING STOCK –
Part 5: Electrotechnical components –
Rules for HV fuses
1 Scope

The purpose of this part of IEC 60077 is to give additional or amended rules for high voltage

(HV) fuses as a supplement to those given by IEC 60077-2.

NOTE 1 In this document the term high voltage fuses is used in the context of the voltages used in the field of

railway rolling stock.

The high voltage fuses concerned are those connected into power and/or auxiliary circuits.

The nominal voltage of these circuits lies between 600 V DC and 3 000 V DC, according to

IEC 60850. These fuses can also be used in auxiliary AC circuits up to a nominal voltage of

1 500 V.

NOTE 2 Certain of these rules, after agreement between the user and the manufacturer, are used for fuses

installed on vehicles other than rail rolling stock such as mine locomotives, trolleybuses, etc.

This document together with IEC 60077-2 states specifically:
a) the characteristics of the fuses;
b) the service conditions with which the fuses comply with reference to:
– operation and behaviour in normal service;
– operation and behaviour in case of short circuit;
– dielectric properties.

c) the tests intended for confirming the compliance of the fuse with the characteristics under

the service conditions and the methods adopted for these tests;
d) the information marked on, or given with, the fuse.
This document does not cover parallel connection of fuses.

During preparation of this document, IEC 60269-1 and IEC 60282-1 have been considered

and their requirements have been kept as far as possible.

This document makes reference to the general rules for electrotechnical components given in

IEC 60077-2, but for general conditions reference is made directly to IEC 60077-1.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements 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 60077-1:2017, Railway applications – Electric equipment for rolling stock – Part 1:

General service conditions and general rules
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SIST EN IEC 60077-5:2020
IEC 60077-5:2019 © IEC 2019 – 7 –

IEC 60077-2:2017, Railway applications – Electric equipment for rolling stock – Part 2:

Electrotechnical components – General rules
IEC 60269-1:2006, Low-voltage fuses – Part 1: General requirements
IEC 60269-1:2006/AMD1:2009
IEC 60269-1:2006/AMD2:2014
IEC 60282-1:2009, High-voltage fuses – Part 1: Current-limiting fuses
IEC 60282-1:2009/AMD1:2014

IEC 61373, Railway applications – Rolling stock equipment – Shock and vibration tests

ISO 3, Preferred numbers – Series of preferred numbers
3 Terms, definitions and abbreviated terms

For the purposes of this document, the terms and definitions given in Clause 3 of

IEC 60077-1:2017 and Clause 3 of IEC 60077-2:2017, and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Components

NOTE For terminologies of a fuse, see also Figure 1 in IEC 60282-1:2009/AMD1:2014.

3.1.1
fuse

device that, by the fusing of one or more of its specifically designed and proportioned

components, opens the circuit in which it is inserted by breaking the current when this

exceeds a given value for a sufficient time
Note 1 to entry: The fuse comprises all the parts that form the complete device.

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-01, modified – The second sentence has

been changed to Note 1 to entry.]
3.1.2
fuse-link

part of a fuse (including the fuse-element(s)) intended to be replaced after the fuse has

operated
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-09]
3.1.3
fuse-element

part of the fuse-link designed to melt under the action of current exceeding some definite

value for a definite period of time
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-08]
3.1.4
fuse-base
fixed part of a fuse provided with contacts and terminals
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SIST EN IEC 60077-5:2020
– 8 – IEC 60077-5:2019 © IEC 2019
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-02]
3.1.5
indicating device,
part of a fuse provided to indicate whether the fuse has operated
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-17]
3.1.6
open box type fuse

fuse installed in an open box equipped with an arc chute in order to reduce arc quickly

3.1.7
homogeneous series,

series of fuse-links, deviating from each other only in such characteristics that, for a given

test, the testing of one or a reduced number of particular fuse-link(s) of that series can be

taken as representative for all the fuse-links of the homogeneous series

Note 1 to entry: The relevant publications specify the characteristics by which the fuse-links of a homogeneous

series may deviate, the particular fuse-links to be tested and the specific test concerned.

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-34, modified – “may” has been replaced

with “can”.]
3.2 Operational characteristics
3.2.1

prospective current,

current that would flow in the circuit if each pole of the switching device or the fuse were

replaced by a conductor of negligible impedance

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-17-01, modified – Note has been deleted.]

3.2.2
prospective peak current

peak value of a prospective current during the transient period following initiation

Note 1 to entry: This term is commonly associated with short-circuit conditions.

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-17-02, modified – Note to entry has been

replaced.]
3.2.3
pre-arcing time

interval of time between the beginning of a current large enough to cause a break in the fuse-

element(s) and the instant when an arc is initiated
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-21]
3.2.4
arcing time,

interval of time between the instant of the initiation of the arc in a pole or a fuse and the

instant of final arc extinction in that pole or that fuse
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-17-37]
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SIST EN IEC 60077-5:2020
IEC 60077-5:2019 © IEC 2019 – 9 –
3.2.5
operating time
sum of the pre-arcing time and the arcing time
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-22]
3.2.6
arc voltage,

instantaneous value of voltage which appears across the terminals of a fuse during the arcing

time
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-30]
3.2.7
peak arc voltage,

maximum instantaneous value of voltage which under prescribed conditions appears across

the terminals of a fuse during the arcing time

Note 1 to entry: After extinction of the arc, an overvoltage (transient recovery voltage) may be present across the

terminals. The value of this will depend on the circuit characteristics and the fuse. This overvoltage is not part of

the peak arc voltage (see Figure D.2 and Figure D.3).

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-17-30, modified – “a pole of a switching

device” has been replaced with “a fuse”. Note 1 to entry has been added.]
3.2.8
DC steady-state recovery voltage

recovery voltage in a DC circuit after the transient voltage phenomena have subsided,

expressed by the mean value where ripple is present
Note 1 to entry: This is shown as B and B in Figure D.2 and Figure D.3.
1 2

[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-17-28, modified – Note 1 to entry has been

added.]
3.2.9
peak let-through current
maximum instantaneous value of current attained during the operation of a fuse
3.2.10
joule integral
I t
integral of the square of the current over a given time interval
2 2
I t= i dt
2 2

Note 1 to entry: The pre-arcing I t is the I t integral extended over the pre-arcing time of the fuse.

2 2

Note 2 to entry: The operating I t is the I t integral extended over the operating time of the fuse.

Note 3 to entry: The energy in joules liberated in one ohm of resistance in a circuit protected by a fuse is equal to

2 2
the value of the operating I t expressed in A s.
[SOURCE: IEC 60050-441:1984/AMD1:2000, 441-18-23]
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SIST EN IEC 60077-5:2020
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3.2.11
time-current characteristic

curve giving the time, e.g. pre-arcing time or operating time, as a function of the prospective

current under stated conditions of operation
...

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