IEC 60127-1:2023

IEC 60127-1 ®
Edition 3.0 2023-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Miniature fuses –
Part 1: Definitions for miniature fuses and general requirements for miniature
fuse-links
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IEC 60127-1 ®
Edition 3.0 2023-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Miniature fuses –
Part 1: Definitions for miniature fuses and general requirements for miniature
fuse-links
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50 ISBN 978-2-8322-7753-9

– 2 – IEC 60127-1:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope and object . 7
2 Normative references . 7
3 Terms and definitions . 8
4 General requirements . 11
5 Standard ratings . 12
6 Marking . 12
7 General notes on tests . 13
7.1 General . 13
7.2 Atmospheric conditions for testing . 13
7.3 Type tests . 13
7.4 Fuse-bases for tests . 14
7.5 Nature of supply. 14
8 Dimensions and construction . 14
8.1 Dimensions . 14
8.2 Construction . 14
8.3 Terminations . 14
8.4 Alignment and configuration of terminations . 15
8.5 Soldered joints . 15
9 Electrical requirements . 15
9.1 Voltage drop . 15
9.2 Time/current characteristic . 15
9.2.1 Time/current characteristic at normal ambient temperature . 15
9.2.2 Test at elevated temperature . 16
9.2.3 Test procedure . 16
9.2.4 Presentation of results . 16
9.3 Breaking capacity . 17
9.3.1 General . 17
9.3.2 Operating conditions . 17
9.3.3 Criteria for satisfactory performance . 18
9.3.4 Insulation resistance . 18
9.3.5 Type test for fuse-links of homogeneous series . 18
9.4 Endurance tests . 18
9.5 Maximum sustained dissipation . 19
9.6 . 19
9.7 Fuse-link temperature . 19
Annex A (informative) Colour coding for miniature fuse-links. 21
Annex B (informative) Example presentations of time/current characteristic . 23
Annex C (informative) Audit testing and surveillance – Guidelines for the application of
the principles of IECEE 03 (CB-FCS) to miniature fuse-links . 25
C.1 Overview. 30
C.2 General . 30
C.3 Properties of miniature fuse-links . 31
C.4 Different types of fuse-links. 31
C.4.1 General . 31
C.4.2 Time/current characteristics . 32

C.4.3 Breaking capacity . 32
C.4.4 Cartridge fuse-links (IEC 60127-2) . 32
C.4.5 Sub-miniature fuse-links (IEC 60127-3) . 33
C.4.6 Universal Modular Fuse-links (IEC 60127-4) . 33
C.4.7 Miniature fuse-links for special applications (IEC 60127-7) . 34
C.5 Applications . 35
C.5.1 Applications – Fuse-link selection criteria . 35
C.5.2 Electrical criteria . 35
C.5.3 Mechanical/physical dimensions . 36
C.6 Protection by I t limitation and pulse operation . 36
C.6.1 I t value . 36
C.6.2 Pulse operation . 36
C.6.3 I t limitation . 37
C.7 Direct current (DC) applications . 37
C.7.1 General information . 37
C.7.2 Battery circuits . 37
C.7.3 Inductive load circuits . 38
C.8 Fuse-holders . 38
C.8.1 Features . 38
C.8.2 Safety aspects . 38
C.8.3 Selection of a fuse-holder . 38
C.8.4 Exchange of fuse-links under load . 39
C.9 Performance on extra-low voltages . 39
C.10 Influence of ambient temperature . 40
Bibliography . 41

Figure A.1 – Layout of colour bands. 21
Figure B.1 – Example presentation of time/current characteristic, ratio 2:1 . 23
Figure B.2 – Example presentation of time/current characteristic, ratio 3:1 . 24
Figure C.1 – Example of power dissipation P and voltage drop U according to rated
current I . 39
N
Figure C.2 – Example of the re-rating of the fuse-link rated current . 40

Table 1 – Prospective current/Breaking Capacity Tolerance . 18
Table A.1 – Colour coding for miniature fuse-links . 22
Table C.1 – Summary of IEC 60127-2 Standard Sheets . 33
Table C.2 – Summary of IEC 60127-3 Standard Sheets . 33
Table C.3 – Summary of IEC 60127-4 Standard Sheets . 34
Table C.4 – Summary of IEC 60127-7 Standard Sheet . 35

– 4 – IEC 60127-1:2023 RLV © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MINIATURE FUSES –
Part 1: Definitions for miniature fuses and
general requirements for miniature fuse-links

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
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6) All users should ensure that they have the latest edition of this publication.
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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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 60127-1:2006+AMD1:2011+AMD2:2015 CSV. A vertical
bar appears in the margin wherever a change has been made. Additions are in green text,
deletions are in strikethrough red text.

IEC 60127-1 has been prepared by subcommittee 32C: Miniature fuses, of IEC technical
committee 32: Fuses. It is an International Standard.
This third edition cancels and replaces the second edition published in 2006,
Amendment 1:2011 and Amendment 2:2015. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) modification of 6.3 to clarify the marking items;
b) modification of 9.3.1 to introduce a tolerance for the prospective current for the breaking
capacity test;
c) deletion of contents of 9.6, Pulse test;
d) deletion of Annex C;
e) addition of new Annex C user guide for miniature fuse-links.
The text of this International Standard is based on the following documents:
Draft Report on voting
32C/615/FDIS 32C/624/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 60127 series, published under the general title Miniature fuses, can
be found on the IEC website.
This Part 1 of the IEC 60127 series covers definitions, general requirements and tests
applicable to all types of miniature fuses (e.g. cartridge fuse-links, sub-miniature fuse-links,
universal modular fuse-links and miniature fuse-links for special applications). All subsequent
parts of the complete series are to be read in conjunction with this Part 1.
IEC 60127 consists of the following parts:
IEC 60127-1, Miniature fuses – Part 1: Definitions for miniature fuses and general requirements
for miniature fuse-links
IEC 60127-2, Miniature fuses – Part 2: Cartridge fuse-links
IEC 60127-3, Miniature fuses – Part 3: Sub-miniature fuse-links
IEC 60127-4, Miniature fuses – Part 4: Universal modular fuse-links (UMF) – Through-hole and
surface mount types
IEC 60127-5, Miniature fuses – Part 5: Guidelines for quality assessment of miniature fuse-links
IEC 60127-6, Miniature fuses – Part 6: Fuse-holders for miniature fuse-links

– 6 – IEC 60127-1:2023 RLV © IEC 2023
IEC 60127-7, Miniature fuses – Part 7: Miniature fuse-links for special applications
IEC 60127-8, Miniature fuses – Part 8: Fuse resistors with particular overcurrent protection
IEC 60127-9, (free for further documents)
IEC 60127-10, Moved to IEC 60127-1 as Annex C.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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.
IMPORTANT – The "colour inside" logo on the cover page of this document 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.

MINIATURE FUSES –
Part 1: Definitions for miniature fuses and
general requirements for miniature fuse-links

1 Scope and object
This part of IEC 60127 covers the general requirements and tests applicable to all types of
miniature fuse-links (e.g. cartridge fuse-links, sub-miniature fuse-links, universal modular fuse-
links and miniature fuse-links for special applications) for the protection of electric appliances,
electronic equipment and component parts thereof normally intended to be used indoors.
This document does not apply to fuses intended for the protection of low-voltage electrical
installations. These are covered by IEC 60269, Low Voltage Fuses.
Specific details covering each major subdivision are given in subsequent parts.
This document does not apply to fuses for appliances intended to be used under special
conditions, such as in a corrosive or explosive atmosphere.
The object of this document is
a) to establish uniform requirements for miniature fuses so as to protect appliances or parts of
appliances in the most suitable way,
b) to define the performance of the fuses, so as to give guidance to designers of electrical
appliances and electronic equipment and to ensure replacement of fuse-links by those of
similar dimensions and characteristics,
c) to define methods of testing,
d) to define maximum sustained dissipation of fuse-links to ensure good compatibility of stated
power acceptance when used with fuse-holders according to this document
(see IEC 60127-6).
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 60038, IEC standard voltages
IEC 60127-6:19942014, Miniature fuses – Part 6: Fuse-holders for miniature fuse-links
Amendment 1 (1996)
Amendment 2 (2003)
– 8 – IEC 60127-1:2023 RLV © IEC 2023
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
fuse
device that, by the fusing of one or more of its specially 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.
3.2
miniature fuse
fuse in which the fuse-link is a miniature fuse-link
3.3
fuse-link
part of a fuse including the fuse-element(s) intended to be replaced after the fuse has operated
3.4
enclosed fuse-link
fuse-link in which the fuse-element is totally enclosed, so that during operation within its rating
it cannot produce any harmful external effects, e.g. due to development of an arc, the release
of gas or the ejection of flame or metallic particles
3.5
miniature fuse-link
enclosed fuse-link for the protection of electric appliances, electronic equipment and component
parts thereof normally intended to be used indoors
3.5.1
cartridge fuse-link
enclosed miniature fuse-link of rated breaking capacity not exceeding 2 kA and which has at
least one of its principle dimensions not exceeding 10 mm
Note 1 to entry: Principle dimensions are length, width, height and diameter.
3.5.2
miniature fuse-link for special applications
enclosed miniature fuse-link which is not covered in IEC 60127-2, IEC 60127-3 or IEC 60127-4
and of rated breaking capacity not exceeding 50 kA and having a width and height not exceeding
12 mm and a length not exceeding 50 mm
3.5.3
sub-miniature fuse-link
miniature fuse-link of which the case (body) has no principal dimension exceeding 10 mm
Note 1 to entry: Principal dimensions are length, width, height and diameter.

3.5.4
universal modular fuse-link
miniature fuse-link primarily adapted for direct electrical connection to printed circuit boards or
other conductive substrates, incorporating features designed to provide a degree of non-
interchangeability where necessary
3.6
fuse-link contact
conductive part of a fuse-link designed to engage with a fuse-base contact or with a fuse-carrier
contact
3.7
fuse-holder
combination of a fuse-base with its fuse-carrier
3.8
fuse-base
fuse-mount
fixed part of a fuse provided with contacts and terminals for connection to the system
3.9
fuse-base contact
fuse-mount contact
conductive part of a fuse-base, connected to a terminal designed to engage with a fuse-carrier
contact or with a fuse-link contact
3.10
fuse-carrier
movable part of a fuse designed to carry a fuse-link
3.11
fuse-carrier contact
conductive part of a fuse-carrier connected to a fuse-link contact and designed to engage with
a fuse-base contact
3.12
fuse-element
part of the fuse-link designed to melt when the fuse operates
3.13
homogeneous series (of fuse-links)
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-links of the series may be taken as
representative of all the fuse-links of the series
Note 1 to entry: Fuse-links are considered as forming a homogeneous series when the characteristics comply with
the following:
– the bodies have the same dimensions, material and method of manufacture;
– the caps or other end closures of the body have the same dimensions, materials and method of attachment and
sealing;
– the granular filler, if any, of the body is of the same material and completeness of filling. It should be of the same
size or any variation of the grain size with current rating should be monotonous;
– the fuse-elements are of the same material with the same principles of design and construction; any changes of
fuse-element dimensions with current rating should be monotonous;
– the rated voltage is the same;
– for low-breaking capacity fuse-links it is only necessary to test the highest rated breaking capacity in a
homogeneous series.
– 10 – IEC 60127-1:2023 RLV © IEC 2023
3.14
rating
general term employed to designate the characteristic values that together define the working
conditions upon which the tests are based and for which the fuse is designed
Examples of rated values usually stated for fuses:
– voltage (U );
N
– current (I );
N
– breaking capacity.
3.15
time/current characteristics (of a fuse-link) for AC
curve giving, under stated conditions of operation, the value of time expressed as virtual time
as a function of the prospective symmetrical current, expressed as the RMS value
Note 1 to entry: Time/current characteristics usually stated for a fuse-link relate to the pre-arcing time and the
operating time.
3.15.1 time/current characteristics (of a fuse-link) for DC
curve giving, under stated conditions of operation, the value of time expressed as actual time
as a function of the DC prospective current
Note 1 to entry: Time/current characteristics usually stated for a fuse-link relate to the pre-arcing time and the
operating time.
3.16
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
3.17
prospective current (of a circuit and with respect to a fuse)
current that would flow in a circuit, if a fuse situated therein were replaced by a link of negligible
impedance
3.18
pre-arcing time (melting time)
interval of time between the beginning of a current large enough to cause a break in the fuse-
element and the instant when an arc is initiated
3.19
arcing time
interval of time between the instant of the initiation of the arc and the instant of final arc
extinction
3.20
operating time (total clearing time)
sum of the pre-arcing time and the arcing time
3.21
virtual time
value of I t divided by the value of the square of the value of the prospective current
Note 1 to entry: The values of the virtual times, usually stated for a fuse-link, are the values of the pre-arcing time
and of the operating time.
3.22
I t (joule integral)
integral of the square of the current over a given time interval:
t
I²t = i dt
∫
t = 0
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 released in 1 Ω of resistance in a circuit protected by a fuse is equal to the
2 2
value of the operating I t expressed in A s.
3.23
breaking capacity of a fuse-link
value (RMS for AC) of prospective current that a fuse-link is capable of breaking at a stated
voltage under prescribed conditions of use and behaviour
3.24
recovery voltage
voltage which appears across the terminals of a fuse after breaking of the current
Note 1 to entry: This voltage may be considered in two successive intervals of time, one during which a transient
voltage exists, followed by a second one during which the power frequency or the steady-state recovery voltage
exists.
3.25
maximum sustained power dissipation
power dissipation of a fuse-link measured under prescribed conditions of measurement at the
maximum current level that can be sustained for a minimum of 1 h or, as specified in the
standard sheet for ratings above 6,3 A
Note 1 to entry: The figure for maximum sustained dissipation is used in connection with the maximum power
acceptance of fuse-holders for miniature fuse-links in accordance with IEC 60127-6.
Note 2 to entry: These values are often exceeded for short periods of time immediately before the fuse-element
melts. Values as high as twice the maximum sustained dissipation have been recorded.
4 General requirements
Fuse-links shall be so constructed that they are reliable and safe in operation and consistent in
performance at any current up to and including the breaking capacity rating and at any voltage
up to the rated voltage, when used within the limits of this document.
During normal use of the fuse-link and within the conditions given in this standard, no permanent
arc, no external arcing, nor any flame that can endanger the surroundings, shall be produced.
During the test for establishing the maximum sustained dissipation and after operation, the
fuse-link shall not have suffered damage hindering its replacement and the marking shall still
be legible.
In general, compliance is checked by carrying out all the tests specified.

– 12 – IEC 60127-1:2023 RLV © IEC 2023
5 Standard ratings
In the relevant standard sheets, values are given for
– rated voltage,
– rated current,
– rated breaking capacity.
6 Marking
6.1 Unless otherwise stated in subsequent parts, the requirements for marking are as follows:
Each fuse-link shall be marked with the below in the order given:
a) A symbol denoting the relative pre-arcing time/current characteristic as given in the relevant
standard sheet. This symbol shall be placed before and adjacent to the rated current.
These symbols read as follows:
FF: denoting very quick acting
F: denoting quick acting
M: denoting medium time-lag
T: denoting time-lag
TT: denoting long time-lag.
b) Rated current in milliamperes (mA) for rated currents below 1 A, and in amperes (A) for
rated currents of 1 A or more. The marking of the rated current shall precede and be adjacent
to the marking of the rated voltage.
To accommodate existing practice in some countries, for the time being, the current may
also be indicated in fractions of ampere.
c) Rated voltage in volts (V).
d) Maker's Manufacturer’s name or trade mark (does not need to follow order of marking).
6.2 Marking shall be indelible and easily legible.
Compliance is checked by inspection and by rubbing the marking by hand for 15 s with a piece
of cloth soaked in water and again for 15 s with a piece of cloth soaked in petroleum spirit.
NOTE 1  For petroleum spirit the use of an aliphatic solvent hexane, with an aromatics content
of maximum 0,1 % volume, a kauri-butanol value of 29, initial boiling point approximately 65 °C,
dry-point approximately 69 °C and specific gravity of approximately 0,68 is recommended.
NOTE 2 In the case of colour coding, the test for indelibility need not be applied.
6.3 The marking according to 6.1 shall be printed on the packing label along with a reference
to the subsequent IEC 60127 standard and appropriate standard sheet. It is optional to indicate
IEC 60127-1 on the packing label. The marking on the packing label shall include the
abbreviation A and or mA for the current rating of the fuse-link.
Compliance is checked by inspection.
6.4 Further identification of the current rating and the time/current characteristics by means
of colour bands may be used.
Such an additional marking shall be in accordance with Annex A.

6.5 Where marking is impractical due to space limitations, the relevant information shall
appear on the smallest package and in the manufacturer's technical literature.
7 General notes on tests
7.1 General
Tests according to this document are type tests.
It is recommended that where acceptance tests are required, they are chosen from the type
tests in this document.
7.2 Atmospheric conditions for testing
7.2.1 Unless otherwise specified in subsequent parts, all tests shall be carried out under the
following atmospheric conditions:
– temperature between 15 °C and 35 °C;
– relative humidity between 45 % and 75 %;
4 5
– air pressure between 8,6 × 10 Pa and 1,06 × 10 Pa.
Where the above-mentioned conditions have a significant influence, they shall be kept
substantially constant during the tests.
Fuse-links shall be tested in the specified bases in free air, and be protected from draughts and
direct heat radiation. The position of the fuse-holder shall be horizontal.
If temperature has a marked effect on the results of the tests, these shall be performed at a
temperature of 23 °C ± 1 °C.
7.2.2 In every test report, the ambient temperature shall be stated. If the standard conditions
for relative humidity or pressure are not fulfilled during tests, a note to this effect shall be added
to the report.
Where tests are required at elevated temperatures, these tests shall be carried out at an
ambient temperature of 70 °C ± 2 °C, unless otherwise specified.
7.3 Type tests
7.3.1 The number of fuse-links required shall be specified in subsequent parts.
Fuse-links shall be tested or inspected in accordance with the following subclauses:
a) Marking (see 6.1)
b) Dimensions (see 8.1)
c) Construction (see 8.2)
d) Voltage drop (see 9.1)
with such additional tests as are specified in subsequent parts.
7.3.2 Based on the results of the test in item 7.3.1 d), the fuse-links shall be sorted in
descending order of voltage drop, and numbered consecutively, lower numbers being allocated
to the fuse-links having the highest voltage drop. Tests from these fuse-links shall then be made
in accordance with the relevant testing schedule.

– 14 – IEC 60127-1:2023 RLV © IEC 2023
If a test is to be repeated, spare fuse-links having approximately the same voltage drop as the
original fuse-links shall be used for the repeat test.
7.3.3
a) No failure is allowed in any of the tests covered by Clauses 6 and 8, nor those described in
9.1, 9.2.2 and 9.7 and such additional clauses and subclauses as shall be specified in
subsequent parts.
b) If in the tests covered by 9.2.1 and 9.3, two failures occur at any one test current, the fuse-
links are deemed not to comply with this document. If, however, one failure occurs, the test
shall be repeated on twice the number of fuse-links, at the same current and a second failure
shall be a cause for rejection.
If two failures occur, but not both in the same test, the fuse-link shall be deemed to comply
provided that there are no further failures in repeat tests with twice the number of fuse-links.
If two failures occur, but not both in the same current, the fuse-link shall be deemed to
comply provided that there are no further failures in repeat tests with twice the number of
fuse-links.
c) In each of the tests according to 9.4, 9.5 and 9.6, one failure is allowed. If two or more fuse-
links fail in any one test, the fuse-links are deemed not to comply with this standard, unless
otherwise specified in subsequent parts.
7.4 Fuse-bases for tests
For tests that require a fuse-base for mounting the fuse-links, a base according to the
requirements specified in subsequent parts shall be used.
7.5 Nature of supply
The nature of the supply for the electrical tests is specified in the relevant clauses or in the
relevant standard sheets in subsequent parts.
For AC, the test voltage is of substantially sinewave form with a frequency between 45 Hz and
62 Hz.
8 Dimensions and construction
8.1 Dimensions
The dimensions of the fuse-links shall comply with the relevant standard sheet, given in
subsequent parts.
Compliance is checked by measurement.
8.2 Construction
The fuse-element shall be completely enclosed. Further details of the construction are given,
as appropriate, in subsequent parts.
8.3 Terminations
Fuse-link contacts shall be made of non-corroding material or of material suitably protected
against corrosion, and shall be effectively free from flux or other non-conducting substance on
their outer surfaces.
Nickel or silver plating is deemed to be adequate protection for brass end caps.
Tests for firm attachment are given, where appropriate, in subsequent parts.

8.4 Alignment and configuration of terminations
Appropriate tests for alignment or position of pins, etc., as applicable, are given in subsequent
parts.
8.5 Soldered joints
Externally visible soldered joints (e.g., on end caps) shall not melt during normal use and
operation.
Compliance is checked by inspection of the soldered joints after the tests described in 9.2.1,
9.2.2, 9.4, 9.5 and 9.6.
9 Electrical requirements
9.1 Voltage drop
The voltage drop across the fuse-links at their rated current shall not exceed the maximum
values given on the relevant standard sheet.
Individual values shall not deviate from the mean value determined for the model under test
during type tests by more than 15 %.
NOTE 1 Attention is drawn to the fact that the second paragraph is based on the assumption that the fuse-links,
which are submitted to a type test, belong to the same manufacturing batch. Where samples are drawn at random,
the condition for the permitted deviation from the mean value need not be fulfilled. If, due to the Peltier effect,
different voltage drops are measured when the current through the fuse-link is reversed, the
highest value shall be taken.
Compliance is checked by measuring the voltage drop when the fuse-link has carried its rated
current for a time sufficient to reach temperature stability.
Direct current shall be used for this test; equipment shall be used which does not influence the
result of the test significantly.
Temperature stability is considered to be reached when the voltage drop changes by less than
2 % of the previously observed value per minute. During this test, the current through the fuse-
link shall not deviate by more than ±1 % from the rated current and the accuracy of the voltage
drop measurement shall be within a tolerance of ±1 %.
NOTE 2 Problems can arise when fuse-links are used at voltages considerably lower than their
rated voltage, mainly for low ratings. Due to the increase of the voltage drop when the element
of a fuse-link approaches its melting point, care should be taken to ensure that there is sufficient
circuit voltage available to cause the fuse-link to interrupt the current when an electrical fault
occurs. Furthermore, fuse-links of the same type and rating may might, due to difference in
design or element material, have different voltage drops and may might therefore not be
interchangeable in practice when used in applications with low circuit voltages, especially in
combination with fuse-links of lower rated currents.
9.2 Time/current characteristic
9.2.1 Time/current characteristic at normal ambient temperature
The time/current characteristic shall be within the limits specified in the relevant standard
sheets.
Compliance is checked by measuring the pre-arcing time under the atmospheric conditions
mentioned in 7.1.
– 16 – IEC 60127-1:2023 RLV © IEC 2023
The current through the fuse-link shall be adjusted to within ±1 % of the required value.
The current stability during the test shall be maintained within ±1 % of the adjusted value. The
voltage of the source shall not exceed the rated voltage of the fuse-link under test. The accuracy
of the measurement of time shall be within a tolerance of ±5 % for times of less than 10 s and
±2 % for times of 10 s or more.
In the case of very short pre-arcing times at high levels of the current where constant current
no longer can be maintained, the I t value should shall be measured and the virtual time be
calculated.
9.2.2 Test at elevated temperature
When specified on the standard sheet, fuse-links shall also be tested for 1 h at an ambient
temperature 70ºC, unless otherwise specified, and with the multiple of the rated current as
specified on the relevant standard sheet.
The current stability during the test shall be maintained within ±2,5 % of the adjusted value.
The fuse-link shall not operate.
9.2.3 Test procedure
Direct current shall be used for these tests.
NOTE 1 Direct current is used because it is easier to control and eliminates the variation inherent with alternating
current caused by the point on the voltage wave that switching occurs.
NOTE 2 Care should be taken that the arcing time is not included in the total time measured
The output voltage of the current source shall be sufficient to limit the variation of current during
the pre-arcing time. Additionally, the output voltage shall not exceed a value declared by the
manufacturer and chosen from the list of DC voltages in Table 6 of IEC 60038:2009.
The time constant of the circuit shall not exceed 3 % of the pre-arcing time.
Where there is a possible influence of the Peltier effect, care should shall be taken to reverse
the direction of the current passing through the fuse-link for each successive sample.
NOTE 3 Where the influence of the Peltier effect is essentially due to the construction, the
time/current characteristic should be tested with twice the number of fuse-links at 2,0 I or 2,1
N
I . The additional samples may be taken from the spare fuse-links.
N
Attention is drawn to the fact that, for certain types of fuse-links, the time/current characteristic
with AC can be significantly different from the characteristic determined with DC and particularly
with currents just exceeding the conventional non-fusing current.
Furthermore, it should be noted that due to the small thermal inertia of the fuse-elements for
low currents, the characteristic of the fuse-links may might change considerably at very low
frequencies.
9.2.4 Presentation of results
If the time/current characteristics with the current as independent variable are pl
...