Low-voltage fuses - Part 5: Guidance for the application of low-voltage fuses

IEC/TR 60269-5:2014 serves as an application guide for low-voltage fuses, shows how current-limiting fuses are easy to apply to protect today's complex and sensitive electrical and electronic equipment. This guidance specifically covers low-voltage fuses up to 1 000 V a.c. and 1 500 V d.c. designed and manufactured in accordance with IEC 60269 series. This guidance provides important facts about as well as information on the application of fuses. This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- recommendations for fuse operations in high altitudes added,
- more details for operational voltages added,
- recommendations for photovoltaic system protection added,
- numerous details improved Keywords: application guide for low-voltage fuses, current-limiting fuses

Fusibles basse tension - Partie 5: Lignes directrices pour l'application des fusibles basse tension

L'IEC/TR 60269-5:2014 est un guide d'application des fusibles basse tension, montre que les fusibles limiteurs de courant sont faciles à utiliser pour protéger le matériel électronique complexe et sensible d'aujourd'hui. Ces lignes directrices couvrent spécifiquement les fusibles basse tension de tensions jusqu'à 1 000 V en courant alternatif et 1 500 V en courant continu selon la série IEC 60269. Elles fournissent des informations sur les fusibles ainsi que sur leurs applications. Cette deuxième édition annule et remplace la première édition parue en 2010. Cette édition constitue une révision technique. Cette édition comporte les modifications techniques suivantes en rapport avec l'édition précédente:
- les recommandations et préconisations pour le fonctionnement des fusibles à des altitudes supérieures;
- l'ajout d'informations concernant les différentes tensions de fonctionnement des fusibles;
- l'ajout de recommandations pour la protection des systèmes photovoltaïques;
- l'amélioration de nombreux détails. Mots clés: guide d'application des fusibles basse tension, les fusibles limiteurs de courant

Nizkonapetostne varovalke - 5. del: Navodila za uporabo nizkonapetostnih varovalk

IEC/TR 60269-5:2014 se uporablja kot navodilo za uporabo nizkonapetostnih varovalk in prikazuje, kako je varovalke, ki omejujejo tok, enostavno uporabiti za zaščito današnje kompleksne in občutljive električne ter elektronske opreme. Ta navodila posebej obravnavajo nizkonapetostne varovalke do 1000 V izmenične napetosti in 1500 V enosmerne napetosti, ki so zasnovane in izdelane v skladu s skupino standardov IEC 60269. V teh navodilih so podana pomembna dejstva in informacije o uporabi varovalk. Druga izdaja razveljavlja in nadomešča prvo izdajo, objavljeno leta 2010. Ta izdaja je tehnično popravljena izdaja. Ta izdaja v primerjavi s prejšnjo vključuje naslednje pomembne tehnične spremembe:
– priporočila za delovanje varovalk na visokih nadmorskih višinah,
– več podrobnosti za delovne napetosti,
– priporočila za zaščito fotonapetostnega sistema,
– številne podrobnosti izboljšanih ključnih besed: navodila za uporabo nizkonapetostnih varovalk, varovalke za omejevanje toka

General Information

Status
Published
Publication Date
20-Apr-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
15-Apr-2022
Due Date
20-Jun-2022
Completion Date
21-Apr-2022

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SLOVENSKI STANDARD
SIST-TP IEC TR 60269-5:2022
01-junij-2022
Nizkonapetostne varovalke - 5. del: Navodila za uporabo nizkonapetostnih
varovalk
Low-voltage fuses - Part 5: Guidance for the application of low-voltage fuses

Fusibles basse tension - Partie 5: Lignes directrices pour l'application des fusibles basse

tension
Ta slovenski standard je istoveten z: IEC TR 60269-5:2014
ICS:
29.120.50 Varovalke in druga Fuses and other overcurrent
nadtokovna zaščita protection devices
SIST-TP IEC TR 60269-5:2022 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST-TP IEC TR 60269-5:2022
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SIST-TP IEC TR 60269-5:2022
IEC TR 60269-5
Edition 2.0 2014-03
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
Low-voltage fuses –
Part 5: Guidance for the application of low-voltage fuses
Fusibles basse tension –
Partie 5: Lignes directrices pour l’application des fusibles basse tension
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XA
ICS 29.120.50 ISBN 978-2-8322-1448-0

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
---------------------- Page: 3 ----------------------
SIST-TP IEC TR 60269-5:2022
– 2 – IEC TR 60269-5:2014 © IEC 2014
CONTENTS

FOREWORD ........................................................................................................................... 6

INTRODUCTION ..................................................................................................................... 8

1 Scope .............................................................................................................................. 9

2 Normative references ...................................................................................................... 9

3 Terms and definitions .................................................................................................... 10

4 Fuse benefits ................................................................................................................. 12

5 Fuse construction and operation .................................................................................... 13

5.1 Components ......................................................................................................... 13

5.2 Fuse-construction ................................................................................................. 13

5.2.1 Fuse link ........................................................................................................ 13

5.2.2 Fuse-link contacts ......................................................................................... 14

5.2.3 Indicating device and striker .......................................................................... 14

5.2.4 Fuse-base ..................................................................................................... 14

5.2.5 Replacement handles and fuse-holders ......................................................... 14

5.3 Fuse operation ...................................................................................................... 15

5.3.1 General ......................................................................................................... 15

5.3.2 Fuse operation in case of short-circuit ........................................................... 15

5.3.3 Fuse operation in case of overload ................................................................ 15

5.3.4 Fuse link pre-arcing time current characteristic: ............................................. 16

5.3.5 Fuse operation in altitudes exceeding 2 000 m .............................................. 17

6 Fuse-combination units .................................................................................................. 18

7 Fuse selection and markings ......................................................................................... 19

8 Conductor protection ..................................................................................................... 21

8.1 General ................................................................................................................. 21

8.2 Utilization category gG ......................................................................................... 22

8.3 Utilization category gN and gD .............................................................................. 23

8.4 Utilization category gR and gS .............................................................................. 23

8.5 Utilization category gU .......................................................................................... 24

8.6 Utilization category gK .......................................................................................... 24

8.7 Utilization category gPV ........................................................................................ 24

8.8 Protection against short-circuit current only .......................................................... 24

9 Selectivity of protective devices ..................................................................................... 24

9.1 General ................................................................................................................. 24

9.2 Selectivity between fuses ...................................................................................... 25

9.2.1 General ......................................................................................................... 25

9.2.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 25

9.2.3 Verification of selectivity for operating time < 0,1 s ........................................ 26

9.2.4 Verification of total selectivity ........................................................................ 26

9.3 Selectivity of circuit-breakers upstream of fuses ................................................... 26

9.3.1 General ......................................................................................................... 26

9.3.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 27

9.3.3 Verification of selectivity for operating time < 0,1 s ........................................ 27

9.3.4 Verification of total selectivity ........................................................................ 27

9.4 Selectivity of fuses upstream of circuit-breakers ................................................... 28

9.4.1 General ......................................................................................................... 28

9.4.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 28

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SIST-TP IEC TR 60269-5:2022
IEC TR 60269-5:2014 © IEC 2014 – 3 –

9.4.3 Verification of selectivity for operating time < 0,1 s ........................................ 28

9.4.4 Verification of total selectivity ........................................................................ 28

10 Short-circuit damage protection ..................................................................................... 30

10.1 General ................................................................................................................. 30

10.2 Short-circuit current paths ..................................................................................... 30

10.3 Current limitation .................................................................................................. 31

10.4 Rated conditional short-circuit current, rated breaking capacity ............................. 31

11 Protection of power factor correction capacitors ............................................................ 31

12 Transformer protection .................................................................................................. 32

12.1 Distribution transformers with a high-voltage primary ............................................ 32

12.2 Distribution transformers with a low-voltage primary ............................................. 33

12.3 Control circuit transformers ................................................................................... 33

13 Motor circuit protection .................................................................................................. 33

13.1 General ................................................................................................................. 33

13.2 Fuse and motor-starter coordination ..................................................................... 34

13.3 Criteria for coordination at the rated conditional short-circuit current I ................. 34

13.4 Criteria for coordination at the crossover current I ............................................. 35

13.5 Criteria for coordination at test current “r” ............................................................. 35

14 Circuit-breaker protection in a.c. and d.c rated voltage circuits ..................................... 36

15 Protection of semiconductor devices in a.c. and d.c. rated voltage circuits .................... 36

16 Fuses in enclosures ....................................................................................................... 38

16.1 General ................................................................................................................. 38

16.2 Limiting temperature of utilization category gG fuse-links according to

IEC 60269-2 – System A ....................................................................................... 38

16.3 Other fuse-links .................................................................................................... 38

17 DC applications ............................................................................................................. 38

17.1 General ................................................................................................................. 38

17.2 Short-circuit protection .......................................................................................... 38

17.3 Overload protection .............................................................................................. 39

17.4 Time-current characteristics .................................................................................. 40

18 Automatic disconnection for protection against electric shock for installations in

buildings ........................................................................................................................ 40

18.1 General ................................................................................................................. 40

18.2 Principle of the protection ..................................................................................... 41

18.3 Examples .............................................................................................................. 42

19 Photovoltaic (PV) system protection .............................................................................. 43

19.1 General ................................................................................................................. 43

19.2 Selection of PV fuse-links ..................................................................................... 44

19.2.1 Fuse utilization category ................................................................................ 44

19.2.2 PV string fuses .............................................................................................. 44

19.2.3 Fuse replacement .......................................................................................... 44

19.2.4 Unearthed or Ungrounded PV Systems .......................................................... 44

19.2.5 Functional earthing fuses ............................................................................... 44

19.2.6 PV array and PV sub-array fuses ................................................................... 45

19.2.7 Fuse monitoring ............................................................................................. 45

19.2.8 Breaking capacity .......................................................................................... 45

19.2.9 Voltage of gPV fuses ..................................................................................... 45

19.2.10 Rated current of gPV fuses ............................................................................ 45

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SIST-TP IEC TR 60269-5:2022
– 4 – IEC TR 60269-5:2014 © IEC 2014

20 Protection of wind mills .................................................................................................. 45

Annex A (informative) Coordination between fuses and contactors/motor-starters ................ 47

A.1 General ................................................................................................................. 47

A.2 Examples of suitable fuse-links used for motor protection ..................................... 47

A.3 Values of I t and cut-off current observed in successful tests of fuse-

link/motor-starter combinations worldwide ............................................................. 48

A.4 Criteria for coordination at the rated conditional short-circuit current I ................. 51

A.4.1 General ......................................................................................................... 51

A.4.2 Maximum operating I t and cut-off current ................................................... 51

A.4.3 Guidance for choosing the maximum rated current of an alternative fuse

type ............................................................................................................... 52

A.4.4 Further guidance ........................................................................................... 52

A.5 Criteria for coordination at test current "r" ............................................................. 53

A.6 Types of coordination ............................................................................................ 54

Bibliography .......................................................................................................................... 57

Figure 1 – Typical fuse-link according to IEC 60269-2........................................................... 13

Figure 2 – Typical fuse-link according to IEC 60269-2........................................................... 14

Figure 3 – Current-limiting fuse operation ............................................................................. 15

Figure 4 – Fuse operation on overload .................................................................................. 16

Figure 5 – Time current characteristic for fuse-links .............................................................. 17

Figure 6 – Currents for fuse-link selection ............................................................................. 23

Figure 7 – Selectivity – General network diagram ................................................................. 25

Figure 8 – Verification of selectivity between fuses F and F for operating time t ≥

2 4

0,1 s ..................................................................................................................................... 26

Figure 9 – Verification of selectivity between circuit-breaker C and fuses F and F ........... 27

2 5 6

Figure 10 – Verification of selectivity between fuse F and circuit-breaker C for

2 3

operating time t ≥ 0,1 s ......................................................................................................... 29

Figure 11 – Verification of selectivity between fuse F and circuit-breaker C for

2 3

operating time t < 0,1 s ......................................................................................................... 30

Figure 12 – Fuse and motor-starter coordination ................................................................... 35

Figure 13 – DC circuit ........................................................................................................... 39

Figure 14 – DC breaking operation ....................................................................................... 39

Figure 15 – Fuse operating time at various d.c. circuit time constants ................................... 40

Figure 16 – Time-current characteristic ................................................................................. 42

Figure A.1 – Collation of cut-off currents observed in successful coordination at I ............... 49

Figure A.2 – Pre-arcing and operating I t values of fuses used in successful

coordination tests as a function of contactor rated current AC3 ............................................. 50

Figure A.3 – Pre-arcing and operating I t values of fuses used in successful

coordination tests as a function of fuse rated current I ........................................................ 51

Figure A.4 – Illustration of the method of selection of the maximum rated current of a

fuse for back-up protection of a contactor of rating I = X amperes ....................................... 54

Figure A.5 – Withstand capabilities of a range of contactors and associated overload

relays at test current "r" ........................................................................................................ 55

Figure A.6 – Illustration of a method of deriving curves of maximum peak current at

test current "r" as a function of fuse rated current ................................................................. 56

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SIST-TP IEC TR 60269-5:2022
IEC TR 60269-5:2014 © IEC 2014 – 5 –

Table 1 – Derating factors for different altitudes .................................................................... 18

Table 2 – Definitions and symbols of switches and fuse-combination units ............................ 19

Table 3 – Fuse application .................................................................................................... 20

Table 4 – Maximum operational voltage of a.c. fuse-links ..................................................... 21

Table 5 – Typical operational voltage ratings of d.c. fuse-links .............................................. 21

Table 6 – Fuse selection for power factor correction capacitors (fuses according to

IEC 60269-2, system A) ........................................................................................................ 32

Table 7 – Conventional non fusing current ............................................................................ 37

Table 8 – Time constants of typical d.c. circuits .................................................................... 40

Table A.1 – Examples of typical fuse-link ratings used for motor-starter protection

illustrating how the category of fuse-link can influence the optimum current rating ................ 48

Table A.2 (Table 12 of IEC 60947-4-1:2009) – Value of the prospective test current

according to the rated operational current ............................................................................. 53

Table A.3 – Types of coordination ......................................................................................... 54

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SIST-TP IEC TR 60269-5:2022
– 6 – IEC TR 60269-5:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE FUSES –
Part 5: Guidance for the application of low-voltage 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

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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

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

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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

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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

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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.

The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".

IEC 60269-5, which is a technical report, has been prepared by subcommittee 32B: Low-

voltage fuses, of IEC technical committee 32: Fuses.

This second edition cancels and replaces the first edition published in 2010. This edition

constitutes a technical revision.
---------------------- Page: 8 ----------------------
SIST-TP IEC TR 60269-5:2022
IEC TR 60269-5:2014 © IEC 2014 – 7 –

This edition includes the following significant technical changes with respect to the previous

edition:
a) recommendations for fuse operations in high altitudes added
b) more details for operational voltages added
c) recommendations for photovoltaic system protection added
d) numerous details improved
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
32B/621A/DTR 32B/624/RVC

Full information on the voting for the approval of this technical report can be found in the

report on voting indicated in the above table.

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

A list of all parts of the IEC 60269 series, under the general title: Low-voltage fuses, can be

found on the IEC website.

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

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
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SIST-TP IEC TR 60269-5:2022
– 8 – IEC TR 60269-5:2014 © IEC 2014
INTRODUCTION

Fuses protect many types of equipment and switchgear against the effects of over-current

which can be dramatic:
– thermal damage of conductors or bus-bars;
– vaporisation of metal;
– ionisation of gases;
– arcing, fire, explosion,
– insulation damage.

Apart from being hazardous to personnel, significant economic losses can result from

downtime and the repairs required to restore damaged equipment.

Modern fuses are common overcurrent protective devices in use today, and as such provide

an excellent cost effective solution to eliminate or minimize the effects of overcurrent.

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SIST-TP IEC TR 60269-5:2022
IEC TR 60269-5:2014 © IEC 2014 – 9 –
LOW-VOLTAGE FUSES –
Part 5: Guidance for the application of low-voltage fuses
1 Scope

This technical report, which serves as an application guide for low-voltage fuses, shows how

current-limiting fuses are easy to apply to protect today's complex and sensitive electrical and

electronic equipment. This guidance specifically covers low-voltage fuses up to 1 000 V a.c.

and 1 500 V d.c. designed and manufactured in accordance with IEC 60269 series. This

guidance provides important facts about as well as information on the application of fuses.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary. Available from
http://www.electropedia.org/

IEC/TR 60146-6, Semiconductor convertors – Part 6: Application guide for the protection of

semiconductor convertors against overcurrent by fuses
IEC 60269 (all parts), Low-voltage fuses
IEC 60269-1:2006, Low-voltage fuses – Part 1: General requirements

IEC 60269-2, Low-voltage fuses – Part 2: Supplementary requirements for fuses for use by

authorized persons (fuses mainly for industrial application) – Examples of standardized

systems of fuses A to K

IEC 60269-3, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use by

unskilled persons (fuses mainly for household or similar applications) – Examples of

standardized systems of fuses A to F

IEC 60269-4:2009, Low-voltage fuses – Part 4: Supplementary requirements for fuse-links for

the protection of semiconductor devices

IEC 60269-6, Low-voltage fuses – Part 6: Supplementary requirements for fuse-links for the

protection of solar photovoltaic energy systems

IEC 60364-4-41:2005, Low-voltage electrical installations – Part 4-41: Protection for safety –

Protection against electric shock

IEC 60364-4-43:2008, Low-voltage electrical installations – Part 4-43: Protection for safety –

Protection against overcurrent

IEC 60364-5-52, Low-voltage electrical installations – Part 5-52: Selection and erection of

electrical equipment – Wiring systems
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SIST-TP IEC TR 60269-5:2022
– 10 – IEC TR 60269-5:2014 © IEC 2014
IEC 60947 (all parts), Low-voltage switchgear and controlgear

IEC 60947-3:2008, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors,

switch-disconnectors and fuse-combination units

IEC 60947-4-1:2009, Low-voltage switchgear and controlgear – Part 4-1: Contactors and

motor-starters – Electromechanical contactors and motor-starters

IEC/TR 61912-1:2007, Low-voltage switchgear and controlgear – Overcurrent protective

devices – Part 1: Application of short-circuit ratings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
switch (mechanical)

mechanical switching device capable of making, carrying and breaking currents under normal

circuit conditions, which may include specified operating overload conditions and also

carrying, for a specified time, currents under specified abnormal conditions such as those of

short-circuits

Note 1 to entry: A switch may be capable of making but not breaking, short-circuit currents.

[SOURC
...

IEC TR 60269-5
Edition 2.0 2014-03
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
Low-voltage fuses –
Part 5: Guidance for the application of low-voltage fuses
Fusibles basse tension –
Partie 5: Lignes directrices pour l’application des fusibles basse tension
IEC TR 60269-5:2014-03(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 60269-5
Edition 2.0 2014-03
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
Low-voltage fuses –
Part 5: Guidance for the application of low-voltage fuses
Fusibles basse tension –
Partie 5: Lignes directrices pour l’application des fusibles basse tension
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XA
ICS 29.120.50 ISBN 978-2-8322-1448-0

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
---------------------- Page: 3 ----------------------
– 2 – IEC TR 60269-5:2014 © IEC 2014
CONTENTS

FOREWORD ........................................................................................................................... 6

INTRODUCTION ..................................................................................................................... 8

1 Scope .............................................................................................................................. 9

2 Normative references ...................................................................................................... 9

3 Terms and definitions .................................................................................................... 10

4 Fuse benefits ................................................................................................................. 12

5 Fuse construction and operation .................................................................................... 13

5.1 Components ......................................................................................................... 13

5.2 Fuse-construction ................................................................................................. 13

5.2.1 Fuse link ........................................................................................................ 13

5.2.2 Fuse-link contacts ......................................................................................... 14

5.2.3 Indicating device and striker .......................................................................... 14

5.2.4 Fuse-base ..................................................................................................... 14

5.2.5 Replacement handles and fuse-holders ......................................................... 14

5.3 Fuse operation ...................................................................................................... 15

5.3.1 General ......................................................................................................... 15

5.3.2 Fuse operation in case of short-circuit ........................................................... 15

5.3.3 Fuse operation in case of overload ................................................................ 15

5.3.4 Fuse link pre-arcing time current characteristic: ............................................. 16

5.3.5 Fuse operation in altitudes exceeding 2 000 m .............................................. 17

6 Fuse-combination units .................................................................................................. 18

7 Fuse selection and markings ......................................................................................... 19

8 Conductor protection ..................................................................................................... 21

8.1 General ................................................................................................................. 21

8.2 Utilization category gG ......................................................................................... 22

8.3 Utilization category gN and gD .............................................................................. 23

8.4 Utilization category gR and gS .............................................................................. 23

8.5 Utilization category gU .......................................................................................... 24

8.6 Utilization category gK .......................................................................................... 24

8.7 Utilization category gPV ........................................................................................ 24

8.8 Protection against short-circuit current only .......................................................... 24

9 Selectivity of protective devices ..................................................................................... 24

9.1 General ................................................................................................................. 24

9.2 Selectivity between fuses ...................................................................................... 25

9.2.1 General ......................................................................................................... 25

9.2.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 25

9.2.3 Verification of selectivity for operating time < 0,1 s ........................................ 26

9.2.4 Verification of total selectivity ........................................................................ 26

9.3 Selectivity of circuit-breakers upstream of fuses ................................................... 26

9.3.1 General ......................................................................................................... 26

9.3.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 27

9.3.3 Verification of selectivity for operating time < 0,1 s ........................................ 27

9.3.4 Verification of total selectivity ........................................................................ 27

9.4 Selectivity of fuses upstream of circuit-breakers ................................................... 28

9.4.1 General ......................................................................................................... 28

9.4.2 Verification of selectivity for operating time ≥ 0,1 s ........................................ 28

---------------------- Page: 4 ----------------------
IEC TR 60269-5:2014 © IEC 2014 – 3 –

9.4.3 Verification of selectivity for operating time < 0,1 s ........................................ 28

9.4.4 Verification of total selectivity ........................................................................ 28

10 Short-circuit damage protection ..................................................................................... 30

10.1 General ................................................................................................................. 30

10.2 Short-circuit current paths ..................................................................................... 30

10.3 Current limitation .................................................................................................. 31

10.4 Rated conditional short-circuit current, rated breaking capacity ............................. 31

11 Protection of power factor correction capacitors ............................................................ 31

12 Transformer protection .................................................................................................. 32

12.1 Distribution transformers with a high-voltage primary ............................................ 32

12.2 Distribution transformers with a low-voltage primary ............................................. 33

12.3 Control circuit transformers ................................................................................... 33

13 Motor circuit protection .................................................................................................. 33

13.1 General ................................................................................................................. 33

13.2 Fuse and motor-starter coordination ..................................................................... 34

13.3 Criteria for coordination at the rated conditional short-circuit current I ................. 34

13.4 Criteria for coordination at the crossover current I ............................................. 35

13.5 Criteria for coordination at test current “r” ............................................................. 35

14 Circuit-breaker protection in a.c. and d.c rated voltage circuits ..................................... 36

15 Protection of semiconductor devices in a.c. and d.c. rated voltage circuits .................... 36

16 Fuses in enclosures ....................................................................................................... 38

16.1 General ................................................................................................................. 38

16.2 Limiting temperature of utilization category gG fuse-links according to

IEC 60269-2 – System A ....................................................................................... 38

16.3 Other fuse-links .................................................................................................... 38

17 DC applications ............................................................................................................. 38

17.1 General ................................................................................................................. 38

17.2 Short-circuit protection .......................................................................................... 38

17.3 Overload protection .............................................................................................. 39

17.4 Time-current characteristics .................................................................................. 40

18 Automatic disconnection for protection against electric shock for installations in

buildings ........................................................................................................................ 40

18.1 General ................................................................................................................. 40

18.2 Principle of the protection ..................................................................................... 41

18.3 Examples .............................................................................................................. 42

19 Photovoltaic (PV) system protection .............................................................................. 43

19.1 General ................................................................................................................. 43

19.2 Selection of PV fuse-links ..................................................................................... 44

19.2.1 Fuse utilization category ................................................................................ 44

19.2.2 PV string fuses .............................................................................................. 44

19.2.3 Fuse replacement .......................................................................................... 44

19.2.4 Unearthed or Ungrounded PV Systems .......................................................... 44

19.2.5 Functional earthing fuses ............................................................................... 44

19.2.6 PV array and PV sub-array fuses ................................................................... 45

19.2.7 Fuse monitoring ............................................................................................. 45

19.2.8 Breaking capacity .......................................................................................... 45

19.2.9 Voltage of gPV fuses ..................................................................................... 45

19.2.10 Rated current of gPV fuses ............................................................................ 45

---------------------- Page: 5 ----------------------
– 4 – IEC TR 60269-5:2014 © IEC 2014

20 Protection of wind mills .................................................................................................. 45

Annex A (informative) Coordination between fuses and contactors/motor-starters ................ 47

A.1 General ................................................................................................................. 47

A.2 Examples of suitable fuse-links used for motor protection ..................................... 47

A.3 Values of I t and cut-off current observed in successful tests of fuse-

link/motor-starter combinations worldwide ............................................................. 48

A.4 Criteria for coordination at the rated conditional short-circuit current I ................. 51

A.4.1 General ......................................................................................................... 51

A.4.2 Maximum operating I t and cut-off current ................................................... 51

A.4.3 Guidance for choosing the maximum rated current of an alternative fuse

type ............................................................................................................... 52

A.4.4 Further guidance ........................................................................................... 52

A.5 Criteria for coordination at test current "r" ............................................................. 53

A.6 Types of coordination ............................................................................................ 54

Bibliography .......................................................................................................................... 57

Figure 1 – Typical fuse-link according to IEC 60269-2........................................................... 13

Figure 2 – Typical fuse-link according to IEC 60269-2........................................................... 14

Figure 3 – Current-limiting fuse operation ............................................................................. 15

Figure 4 – Fuse operation on overload .................................................................................. 16

Figure 5 – Time current characteristic for fuse-links .............................................................. 17

Figure 6 – Currents for fuse-link selection ............................................................................. 23

Figure 7 – Selectivity – General network diagram ................................................................. 25

Figure 8 – Verification of selectivity between fuses F and F for operating time t ≥

2 4

0,1 s ..................................................................................................................................... 26

Figure 9 – Verification of selectivity between circuit-breaker C and fuses F and F ........... 27

2 5 6

Figure 10 – Verification of selectivity between fuse F and circuit-breaker C for

2 3

operating time t ≥ 0,1 s ......................................................................................................... 29

Figure 11 – Verification of selectivity between fuse F and circuit-breaker C for

2 3

operating time t < 0,1 s ......................................................................................................... 30

Figure 12 – Fuse and motor-starter coordination ................................................................... 35

Figure 13 – DC circuit ........................................................................................................... 39

Figure 14 – DC breaking operation ....................................................................................... 39

Figure 15 – Fuse operating time at various d.c. circuit time constants ................................... 40

Figure 16 – Time-current characteristic ................................................................................. 42

Figure A.1 – Collation of cut-off currents observed in successful coordination at I ............... 49

Figure A.2 – Pre-arcing and operating I t values of fuses used in successful

coordination tests as a function of contactor rated current AC3 ............................................. 50

Figure A.3 – Pre-arcing and operating I t values of fuses used in successful

coordination tests as a function of fuse rated current I ........................................................ 51

Figure A.4 – Illustration of the method of selection of the maximum rated current of a

fuse for back-up protection of a contactor of rating I = X amperes ....................................... 54

Figure A.5 – Withstand capabilities of a range of contactors and associated overload

relays at test current "r" ........................................................................................................ 55

Figure A.6 – Illustration of a method of deriving curves of maximum peak current at

test current "r" as a function of fuse rated current ................................................................. 56

---------------------- Page: 6 ----------------------
IEC TR 60269-5:2014 © IEC 2014 – 5 –

Table 1 – Derating factors for different altitudes .................................................................... 18

Table 2 – Definitions and symbols of switches and fuse-combination units ............................ 19

Table 3 – Fuse application .................................................................................................... 20

Table 4 – Maximum operational voltage of a.c. fuse-links ..................................................... 21

Table 5 – Typical operational voltage ratings of d.c. fuse-links .............................................. 21

Table 6 – Fuse selection for power factor correction capacitors (fuses according to

IEC 60269-2, system A) ........................................................................................................ 32

Table 7 – Conventional non fusing current ............................................................................ 37

Table 8 – Time constants of typical d.c. circuits .................................................................... 40

Table A.1 – Examples of typical fuse-link ratings used for motor-starter protection

illustrating how the category of fuse-link can influence the optimum current rating ................ 48

Table A.2 (Table 12 of IEC 60947-4-1:2009) – Value of the prospective test current

according to the rated operational current ............................................................................. 53

Table A.3 – Types of coordination ......................................................................................... 54

---------------------- Page: 7 ----------------------
– 6 – IEC TR 60269-5:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE FUSES –
Part 5: Guidance for the application of low-voltage fuses
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

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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

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

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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.

The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".

IEC 60269-5, which is a technical report, has been prepared by subcommittee 32B: Low-

voltage fuses, of IEC technical committee 32: Fuses.

This second edition cancels and replaces the first edition published in 2010. This edition

constitutes a technical revision.
---------------------- Page: 8 ----------------------
IEC TR 60269-5:2014 © IEC 2014 – 7 –

This edition includes the following significant technical changes with respect to the previous

edition:
a) recommendations for fuse operations in high altitudes added
b) more details for operational voltages added
c) recommendations for photovoltaic system protection added
d) numerous details improved
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
32B/621A/DTR 32B/624/RVC

Full information on the voting for the approval of this technical report can be found in the

report on voting indicated in the above table.

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

A list of all parts of the IEC 60269 series, under the general title: Low-voltage fuses, can be

found on the IEC website.
The committee has decided that the contents of this publication will remain unch
...

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