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

Gives additional or amended rules for high voltage fuses as a supplement to those given by EN 60077-2. States specifically the characteristics of the fuses, their service conditions, the tests to be performed, and the markings.

Bahnanwendungen - Elektrische Betriebsmittel auf Bahnfahrzeugen - 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

Fournit des prescriptions complémentaires ou modifiées pour les fusibles à haute tension en supplément à celles données dans la EN 60077-2. Définit spécifiquement les caractéristiques des fusibles, leurs conditions de service, les essais à effectuer, et les marquages.

Železniške naprave – Elektrotehnična oprema za vozna sredstva – 5. del: Elektrotehnične komponente – Pravila za visokonapetostne varovalke (IEC 60077- 5:2003)

General Information

Status
Published
Publication Date
09-Sep-2003
Current Stage
6060 - Document made available
Start Date
10-Sep-2003
Completion Date
10-Sep-2003

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SLOVENSKI STANDARD
SIST EN 60077-5:2004
01-september-2004
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Railway applications - Electrotechnical equipment for rolling stock -- Part 5:
Electrotechnical components - Rules for HV fuses
Bahnanwendungen - Elektrische Betriebsmittel auf Bahnfahrzeugen -- 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
Ta slovenski standard je istoveten z: EN 60077-5:2003
ICS:
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
29.280 (OHNWULþQDYOHþQDRSUHPD Electric traction equipment
SIST EN 60077-5:2004 en

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

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD EN 60077-5
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2003
ICS 45.060
English version
Railway applications -
Electrotechnical equipment for rolling stock
Part 5: Electrotechnical components -
Rules for HV fuses
(IEC 60077-5:2003)
Applications ferroviaires - Bahnanwendungen -
Equipements électriques Elektrische Betriebsmittel
du matériel roulant auf Bahnfahrzeugen
Partie 5: Composants électrotechniques - Teil 5: Elektrotechnische Bauteile -
Règles pour les fusibles à haute tension Regeln für Hochspannungssicherungen
(CEI 60077-5:2003) (IEC 60077-5:2003)

This European Standard was approved by CENELEC on 2003-09-01. 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, Czech Republic,

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

Netherlands, Norway, Portugal, Slovakia, 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

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60077-5:2003 E
---------------------- Page: 2 ----------------------
EN 60077-5:2003 - 2 -
Foreword

The text of document 9/752/FDIS, future edition 1 of IEC 60077-5, prepared by IEC TC 9, Electrical

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

approved by CENELEC as EN 60077-5 on 2003-09-01.

This standard should be read in conjunction with EN 60077-1:2002 and EN 60077-2:2002.

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) 2004-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-09-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.

In this standard, annexes A and ZA are normative and annexes B to D are informative.

Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 60077-5:2003 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 3 ----------------------
- 3 - EN 60077-5:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

This European Standard incorporates by dated or undated reference, provisions from other

publications. These normative references are cited at the appropriate places in the text and the

publications are listed hereafter. For dated references, subsequent amendments to or revisions of any

of these publications apply to this European Standard only when incorporated in it by amendment or

revision. For undated references the latest edition of the publication referred to applies (including

amendments).

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 60050-441 1984 International Electrotechnical - -
Vocabulary (IEV)
Chapter 441: Switchgear, controlgear
and fuses
IEC 60050-811 1991 Chapter 811: Electric traction - -
IEC 60077-1 1999 Railway applications - Electric EN 60077-1 2002
(mod) equipment for rolling stock
Part 1: General service conditions and
general rules
IEC 60077-2 1999 Part 2: Electrotechnical components - EN 60077-2 2002
(mod) General rules
IEC 60269-1 1998 Low-voltage fuses EN 60269-1 1998
Part 1: General requirements
IEC 60282-1 2002 High-voltage fuses EN 60282-1 2002
Part 1: Current-limiting fuses
IEC 60850 2000 Railway applications - Supply voltages - -
of traction systems
IEC 61373 1999 Railway applications - Rolling stock EN 61373 1999
equipment - Shock and vibration tests
ISO 3 1973 Preferred numbers - Series of preferred - -
numbers
---------------------- Page: 4 ----------------------
NORME
CEI
INTERNATIONALE IEC
60077-5
INTERNATIONAL
Première édition
STANDARD
First edition
2003-07
Applications ferroviaires –
Equipements électriques du matériel roulant –
Partie 5:
Composants électrotechniques –
Règles pour les fusibles à haute tension
Railway applications –
Electric equipment for rolling stock –
Part 5:
Electrotechnical components –
Rules for HV fuses
© IEC 2003 Droits de reproduction réservés ⎯ Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from

microfilms, sans l'accord écrit de l'éditeur. the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch

CODE PRIX
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
ɆɟɠɞɭɧɚɪɨɞɧɚɹɗɥɟɤɬɪɨɬɟɯɧɢɱɟɫɤɚɹɄɨɦɢɫɫɢɹ
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 5 ----------------------
60077-5 © IEC:2003 – 3 –
CONTENTS

FOREWORD .......................................................................................................................... 7

1 Scope and object ............................................................................................................11

2 Normative references......................................................................................................11

3 Definitions.......................................................................................................................13

3.1 Components ..........................................................................................................13

3.2 Operational characteristics.....................................................................................15

4 Classification ..................................................................................................................19

4.1 Breaking range (see also Annex B) ........................................................................19

4.2 Utilisation category.................................................................................................19

5 Characteristics................................................................................................................19

6 Product information.........................................................................................................21

6.1 Documentation.......................................................................................................21

6.2 Marking .................................................................................................................21

7 Normal service conditions ...............................................................................................21

8 Constructional and performance requirements.................................................................23

8.1 Constructional requirements...................................................................................23

8.2 Performance requirements .....................................................................................23

9 Tests ..............................................................................................................................27

9.1 Kinds of tests.........................................................................................................27

9.2 Tests for the verification of constructional requirements .........................................29

9.3 Type tests for the verification of performance requirements ....................................29

9.4 Routine tests for the verification of performance requirements................................45

Annex A (normative) Connection diagram for temperature-rise tests ......................................47

Annex B (informative) Comparison between “a” and “g” fuse time current characteristics .......49

Annex C (informative) Diagram of the test circuit for breaking capacity tests ..........................51

Annex D (informative) Verification of breaking capacity..........................................................53

Figure A.1 – Connection diagram for temperature-rise tests ...................................................47

Figure B.1 – Comparison between “a” and “g” fuse time current characteristics ......................49

Figure C.1 – Diagram of the test circuit for breaking capacity tests.........................................51

Figure D.1 – Test circuit calibration........................................................................................53

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

of the current.........................................................................................................................55

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

value of the current ...............................................................................................................55

Table 1 – Conventional times for “g” fuse-links ......................................................................21

Table 2 – Rated and test voltages for d.c. fuse-links supplied from the contact line ................25

---------------------- Page: 6 ----------------------
60077-5 © IEC:2003 – 5 –

Table 3 – Sequence of tests for the highest rating of a homogenous series ............................31

Table 4 – Sequence of tests for the lowest rating of a homogenous series .............................33

Table 5 – Sequence of tests for intermediate ratings of a homogenous series ........................35

Table 6 – Tolerances on test values ......................................................................................35

Table 7 – Parameters for breaking capacity tests of d.c. fuse-links.........................................39

Table 8 – Time constant of the test circuit..............................................................................41

---------------------- Page: 7 ----------------------
60077-5 © IEC:2003 – 7 –
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, 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 60077-5 has been prepared by IEC technical committee 9: Electrical

equipment and systems for railways.
This standard shall be read in conjunction with IEC 60077-1 and IEC 60077-2.
The text of this standard is based on the following documents:
FDIS Report on voting
9/752/FDIS 9/762/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.
---------------------- Page: 8 ----------------------
60077-5 © IEC:2003 – 9 –

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

IEC 60077 consists of the following parts under the general title Railway applications – Electric

equipment for rolling stock:
Part 1 – General service conditions and general rules
Part 2 – Electrotechnical components – General rules
Part 3 – Electrotechnical components – Rules for d.c. circuit-breakers
Part 4 – Electrotechnical components – Rules for a.c. circuit-breakers
Part 5 – Electrotechnical components – Rules for HV fuses

The committee has decided that the contents of this publication will remain unchanged until 2011.

At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
---------------------- Page: 9 ----------------------
60077-5 © IEC:2003 – 11 –
RAILWAY APPLICATIONS –
ELECTRIC EQUIPMENT FOR ROLLING STOCK –
Part 5: Electrotechnical components –
Rules for HV fuses
1 Scopeand object

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

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

NOTE In this product standard 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 to be connected into power and/or auxiliary

circuits. The nominal voltage of these circuits lies between 600 V d.c. and 3 000 V d.c.,

according to IEC 60850. These fuses may also be used in auxiliary a.c. circuits up to a nominal

voltage of 1 500 V.

NOTE Certain of these rules may, after agreement between user and manufacturer, be used for fuses installed on

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

This product standard together with IEC 60077-2 states specifically:
a) the characteristics of the fuses;
b) the service conditions with which the fuses have to 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 to be adopted for these tests;
d) the information to be marked on, or given with, the fuse.
This standard does not cover parallel connection of fuses.

During preparation of this product standard, IEC 60269-1 and IEC 60282-1 have been

considered and their requirements have been kept as far as possible.

This product standard 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 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.
---------------------- Page: 10 ----------------------
60077-5 © IEC:2003 – 13 –

IEC 60050(441):1984, International Electrotechnical Vocabulary (IEV) – Chapter 441: Switch-

gear, controlgear and fuses

IEC 60050(811):1991, International Electrotechnical Vocabulary (IEV) – Chapter 811: Electric

traction

IEC 60077-1:1999, Railway applications – Electric equipment for rolling stock – Part 1: General

service conditions and general rules

IEC 60077-2:1999, Railway applications – Electric equipment for rolling stock – Part 2:

Electrotechnical components – General rules
IEC 60269-1:1998, Low-voltage fuses – Part 1: General requirements
IEC 60282-1:2002, High-voltage fuses – Part 1: Current – limiting fuses
IEC 60850:2000, Railway applications – Supply voltages of traction systems

IEC 61373:1999, Railway applications – Rolling stock equipment – Shock and vibration tests

ISO 3:1973, Preferred numbers – Series of preferred numbers
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60077-1 and

IEC 60077-2 together with the following definitions apply.
3.1 Components
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. The fuse comprises all the parts that form the

complete device.
[IEV 441-18-01]
3.1.2
fuse-link

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

operated
[IEV 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
[IEV 441-18-08]
3.1.4
fuse-base
fixed part of a fuse provided with contacts and terminals
[IEV 441-18-02]
---------------------- Page: 11 ----------------------
60077-5 © IEC:2003 – 15 –
3.1.5
indicating device
part of a fuse provided to indicate whether the fuse has operated
[IEV 441-18-17]
3.2 Operational characteristics
3.2.1
prospective current

current that would flow in the circuit if the fuse were replaced by a conductor of negligible

impedance
[IEV 441-17-01, modified]
3.2.2
prospective peak current

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

[IEV 441-17-02, modified]
NOTE This term is commonly associated with short-circuit conditions.
3.2.3
pre-arcing time

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

elements and the instant when an arc is initiated
[IEV 441-18-21]
3.2.4
arcing time

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

arc extinction in that fuse
[IEV 441-17-37, modified]
3.2.5
operating time
sum of the pre-arcing time and the arcing time
[IEV 441-18-22]
3.2.6
arc voltage

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

time
[IEV 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
[IEV 441-17-30, modified]

NOTE 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 Figures D.2 and D.3).
---------------------- Page: 12 ----------------------
60077-5 © IEC:2003 – 17 –
3.2.8
d.c. or power frequency steady-state recovery voltage

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

by the mean value where ripple is present
[IEV 441-17-28, modified]
NOTE This is shown as B and B in Figures D.2 and D.3.
1 2
3.2.9
peak let-through current
maximum instantaneous value of current attained during the operation of a fuse
[IEV 441-17-12, modified]
3.2.10
I t; Joule integral
integral of the square of the current over a given time interval
[IEV 441-18-23]
It = i dt
2 2

NOTE 1 The pre-arcing I t is the I t integral extended over the pre-arcing time of the fuse.

2 2

NOTE 2 The operating I t is the I t integral extended over the operating time of the fuse.

NOTE 3 The energy in joules liberated in one ohm of resistance in a circuit protected by a fuse is equal to the

value of the operating I t expressed in A s.
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
[IEV 441-17-13]
3.2.12
conventional non-fusing current

value of current specified as that which the fuse-link is capable of carrying for a specified time

(conventional time) without melting
[IEV 441-18-27]
3.2.13
conventional fusing current

value of current specified as that which causes operation of the fuse-link within a specified time

(conventional time)
[IEV 441-18-28]
3.2.14
rated value

quantity value, generally assigned by a manufacturer, for a specified operating condition of a fuse

[IEV 811-11-02, modified]

NOTE The rated values usually stated for fuses are voltage, current, breaking capacity and power dissipation.

---------------------- Page: 13 ----------------------
60077-5 © IEC:2003 – 19 –
4 Classification
4.1 Breaking range (see also Annex B)
Fuse-links are classified according to whether they are:

“g” fuse-link – with a full range breaking capacity, i.e. capable under specified conditions of

breaking all currents which cause melting of the fuse-element up to its rated breaking capacity;

“a” fuse-link – with a partial range breaking capacity, i.e. capable of breaking under specified

conditions all currents between their minimum breaking capacity and their rated breaking

capacity. They may be used in conjunction with another switching device where protection is

required against over-currents below their minimum breaking capacity.

NOTE Examples of “a” fuse-link protection may be those for protection of semi-conductor devices, motors, etc.

4.2 Utilisation category

Fuse-links may be categorised according to whether they are to be subjected in normal service

to:
– current values which do not exceed their continuous rating;

– current values which briefly exceed their continuous rating on a regular basis, such as when

starting a rotating machine;

– current values which do not exceed their continuous rating but which are switched or

change significantly in a frequently repeated pattern;
or they have to provide a special protection as, for example:

– semi-conductor conditions, where fast action is required in order to limit the peak let-

through current and the operating I t;
– provide a time delayed operation.
5 Characteristics
The characteristics of a fuse shall be stated in terms of the following:
– rated voltage(s) d.c. and/or a.c.;
– rated current (I );
– rated frequency;
– rated breaking capacity;
– breaking range;
– rated power dissipation;

– time-current characteristics. The conventional times and currents for “g” fuse-links are

given in Table 1;
– overload capability;
2 2 2
– I t characteristics (minimum pre-arcing I t and maximum operating I t);
– peak let-through current related to prospective current and time constant;
– current rating correction factors versus ambient temperature;
– peak arc voltage related to operating voltage;
– rated insulation voltage for fuse-bases.
---------------------- Page: 14 ----------------------
60077-5 © IEC:2003 – 21 –

When presented graphically, the I t characteristics shall be given with prospective current as

abscissa and I t values as ordinate. Logarithmic scales shall be used on both co-ordinate

axes.
Table 1 – Conventional times for “g” fuse-links
Specified time
Rated current
(conventional time)
I ≤ 63 1
63 < I ≤ 160
160 < I ≤ 400
I > 400
6 Product information
6.1 Documentation
This information shall be given in the manufacturer's catalogue or manual.
Subclause 6.1 of IEC 60077-2 applies, supplemented by the following:
– rated voltage;
– rated current;
– rated breaking capacity and time constant;
– suitable applications – see 4.2;
2 2 2
– I t characteristics (minimum pre-arcing I t and maximum operating I t);

– correction factors for current rating versus ambient temperature, varying load and overload;

– physical dimensions;
– special instructions for storage, installation, maintenance, if applicable.
6.2 Marking

Fuse-links and fuse-bases shall possess durable and legible nameplates or engraved markings

in accordance with 6.2 of IEC 60077-2.
The markings of the fuse-link and fuse-base shall include the following data:
– manufacturer's name or trade mark;
– manufacturer's type designation;
– rated voltage (d.c. and/or a.c.);
– rated current.
7 Normal service conditions
These conditions are given in Clause 7 of IEC 60077-1.
---------------------- Page: 15 ----------------------
60077-5 © IEC:2003 – 23 –
8 Constructional and performance requirements
8.1 Constructional requirements

In addition to the requirements of 8.1 of IEC 60077-2, the fuse shall comply with the following

requirements.
8.1.1 Fuse-link

The fuse-link shall be sufficiently robust so that there shall be no damage to the surroundings

e.g. by permanent arcing, flashover or any ejection of flames or materials during operation.

It shall be possible to replace the fuse-links easily.
NOTE For further details, see 8.5.8. of IEC 60269-1.
8.1.2 Fuse-base

The fuse-base shall incorporate contacts which ensure that the connections to the fuse-link are

adequate under all conditions of thermal cycling, vibration and shock during normal service and

during the application of the electro-dynamic forces when the fuse-link is rupturing overload or

short-circuit currents up to its rated breaking capacity value.
8.1.3 Spring-loaded contacts

Where the fuse-base incorporates spring-loaded contacts for electrical connection and

mechanical retention of the fuse-link, these contacts shall withstand 100 cycles of insertions

and removals of the fuse-link without deterioration of the electrical and mechanical properties.

8.1.4 External terminals

Terminals for external connection to the fuse-base shall provide a constant clamping force

unaffected by variation in current through them. They shall be capable of enduring multiple

connection and disconnection of the external conductors without deterioration. Terminal screw

thread shall have a minimum size of M5.

Terminals shall be such that they cannot turn or be displaced when the connecting screws are

tightened, and such that the conductors cannot be displaced.

The parts gripping the conductors shall be of metal and shall have a shape such that

...

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