SIST EN 60539-1:2016

SLOVENSKI STANDARD
01-oktober-2016
1DGRPHãþD
SIST EN 60539-1:2008
Neposredno ogrevani termistorji z negativnim koeficientom - 1. del: Rodovna
specifikacija (IEC 60539-1:2016)
Directly heated negative temperature coefficient thermistors - Part 1: Generic
specification (IEC 60539-1:2016)
Thermistances à coefficient de température négatif à chauffage direct - Partie 1:
Spécification générique
Ta slovenski standard je istoveten z: EN 60539-1:2016
ICS:
31.040.30 Termistorji Thermistors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60539-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2016
ICS 31.040.30 Supersedes EN 60539-1:2008
English Version
Directly heated negative temperature coefficient thermistors -
Part 1: Generic specification
(IEC 60539-1:2016)
Thermistances à coefficient de température négatif à Direkt geheizte temperaturabhängige Widerstände mit
chauffage direct - Partie 1: Spécification générique negativem Temperaturkoeffizienten -
(IEC 60539-1:2016) Teil 1: Fachgrundspezifikation
(IEC 60539-1:2016)
This European Standard was approved by CENELEC on 2016-06-01. 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 CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60539-1:2016 E
European foreword
The text of document 40/2430/FDIS, future edition 3 of IEC 60539-1, prepared by IEC/TC 40
"Capacitors and resistors for electronic equipment" was submitted to the IEC-CENELEC parallel vote
and approved by CENELEC as EN 60539-1:2016.
The following dates are fixed:
(dop) 2017-03-01
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2019-06-01
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 60539-1:2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 60539-1:2016 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60027-1 NOTE Harmonized as EN 60027-1.
ISO 80000-1:2009 NOTE Harmonized as EN ISO 80000-1:2013 (not modified).
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is
available here: www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 60062 -  Marking codes for resistors and EN 60062 -
capacitors
IEC 60068-1 2013 Environmental testing - EN 60068-1 2014
Part 1: General and guidance
IEC 60068-2-1 -  Environmental testing - EN 60068-2-1 -
Part 2-1: Tests - Test A: Cold
IEC 60068-2-2 -  Environmental testing - EN 60068-2-2 -
Part 2-2: Tests - Test B: Dry heat
IEC 60068-2-6 -  Environmental testing - EN 60068-2-6 -
Part 2-6: Tests - Test Fc: Vibration
(sinusoidal)
IEC 60068-2-11 -  Basic environmental testing EN 60068-2-11 -
procedures -
Part 2-11: Tests - Test Ka: Salt mist
IEC 60068-2-14 -  Environmental testing - EN 60068-2-14 -
Part 2-14: Tests - Test N: Change of
temperature
IEC 60068-2-17 -  Basic environmental testing EN 60068-2-17 -
procedures -
Part 2-17: Tests - Test Q: Sealing
IEC 60068-2-20 -  Environmental testing - EN 60068-2-20 -
Part 2-20: Tests - Test T: Test methods
for solderability and resistance to
soldering heat of devices with leads
IEC 60068-2-21 -  Environmental testing - EN 60068-2-21 -
Part 2-21: Tests - Test U: Robustness of
terminations and integral mounting
devices
IEC 60068-2-27 -  Environmental testing - EN 60068-2-27 -
Part 2-27: Tests - Test Ea and guidance:
Shock
Publication Year Title EN/HD Year
IEC 60068-2-31 -  Environmental testing - EN 60068-2-31 -
Part 2-31: Tests - Test Ec: Rough
handling shocks, primarily for
equipment-type specimens
IEC 60068-2-38 -  Environmental testing - EN 60068-2-38 -
Part 2-38: Tests - Test Z/AD: Composite
temperature/humidity cyclic test
IEC 60068-2-45 1980 Basic environmental testing EN 60068-2-45 1992
procedures -
+ A1 1993 + A1 1993
Part 2-45: Tests - Test XA and
guidance: Immersion in cleaning
solvents
IEC 60068-2-52 -  Environmental testing - EN 60068-2-52 -
Part 2-52: Tests - Test Kb: Salt mist,
cyclic (sodium chloride solution)
IEC 60068-2-54 -  Environmental testing - EN 60068-2-54 -
Part 2-54: Tests - Test Ta: Solderability
testing of electronic components by the
wetting balance method
IEC 60068-2-58 -  Environmental testing - EN 60068-2-58 -
Part 2-58: Tests - Test Td: Test methods
for solderability, resistance to dissolution
of metallization and to soldering heat of
surface mounting devices (SMD)
IEC 60068-2-69 -  Environmental testing - EN 60068-2-69 -
Part 2: Tests - Test Te: Solderability
testing of electronic components for
surface mounting devices (SMD) by the
wetting balance method
IEC 60068-2-78 -  Environmental testing - EN 60068-2-78 -
Part 2-78: Tests - Test Cab: Damp heat,
steady state
IEC 60294 -  Measurement of the dimensions of a EN 60294 -
cylindrical component with axial
terminations
IEC 60717 -  Method for the determination of the EN 60717 -
space required by capacitors and
resistors with unidirectional terminations
IEC 61193-2 -  Quality assessment systems - EN 61193-2 -
Part 2: Selection and use of sampling
plans for inspection of electronic
components and packages
IEC 61249-2-7 -  Materials for printed boards and other EN 61249-2-7 -
interconnecting structures -
Part 2-7: Reinforced base materials,
clad and unclad - Epoxide woven
E-glass laminated sheet of defined
flammability (vertical burning test),
copper-clad
IEC 60539-1 ®
Edition 3.0 2016-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Directly heated negative temperature coefficient thermistors –

Part 1: Generic specification
Thermistances à coefficient de température négatif à chauffage direct –

Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.040.30 ISBN 978-2-8322-3307-8

– 2 – IEC 60539-1:2016  IEC 2016
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references. 9
3 Terms and definitions . 10
4 General items . 20
4.1 Units and symbols . 20
4.2 Preferred values and appropriate category . 20
4.2.1 General . 20
4.2.2 Appropriate category . 20
4.3 Marking . 20
4.3.1 General . 20
4.3.2 Marking for small size types such as surface mount thermistors . 21
4.3.3 Coding . 21
4.4 Quality assessment procedures . 21
5 Test and measurement procedures . 21
5.1 General . 21
5.2 Standard atmospheric conditions for testing . 21
5.3 Drying and recovery . 22
5.3.1 Drying . 22
5.3.2 Recovery . 22
5.4 Mounting (for surface mount thermistors only) . 22
5.4.1 General . 22
5.4.2 Substrate and pad . 22
5.4.3 Mounting on board . 22
5.5 Visual examination and check of dimensions . 23
5.5.1 Visual examination . 23
5.5.2 Dimensions . 24
5.6 Zero-power resistance . 24
5.6.1 General . 24
5.6.2 Measurement procedures . 24
5.6.3 Requirements . 24
5.7 B-value or resistance ratio . 25
5.7.1 General . 25
5.7.2 Requirements . 25
5.8 Insulation resistance (for insulated types only) . 25
5.8.1 General . 25
5.8.2 Test methods . 25
5.8.3 Applied voltage . 27
5.8.4 Requirements . 28
5.9 Voltage proof (for insulated types only) . 28
5.9.1 General . 28
5.9.2 Test voltage . 28
5.9.3 Requirements . 28
5.10 Resistance/temperature characteristic . 28
5.10.1 General . 28
5.10.2 Test methods . 28
5.10.3 Requirements . 28

IEC 60539-1:2016  IEC 2016 – 3 –
5.11 Dissipation factor (δ) . 28
5.11.1 General . 28
5.11.2 Initial measurements . 29
5.11.3 Test methods . 29
5.11.4 Requirements . 30
5.12 Thermal time constant by ambient temperature change (τ ) . 30
a
5.12.1 General . 30
5.12.2 Initial measurements . 30
5.12.3 Preconditioning . 31
5.12.4 Test methods . 31
5.12.5 Final measurements and requirements . 31
5.12.6 Requirements . 31
5.13 Thermal time constant by cooling after self-heating (τ ) . 31
c
5.13.1 General . 31
5.13.2 Initial measurements . 31
5.13.3 Preconditioning . 31
5.13.4 Test method . 32
5.13.5 Final measurements and requirements . 32
5.14 Robustness of terminations (not applicable to surface mount thermistors) . 32
5.14.1 General . 32
5.14.2 Initial measurements . 32
5.14.3 Test methods . 33
5.14.4 Test Ua – Tensile . 33
5.14.5 Test Ub – Bending (half the number of terminations) . 33
5.14.6 Test Uc – Torsion (remaining terminations) . 33
5.14.7 Final measurements and requirements . 33
5.15 Resistance to soldering heat . 33
5.15.1 General . 33
5.15.2 Preconditioning . 34
5.15.3 Test procedure . 34
5.15.4 Recovery . 34
5.15.5 Final inspection, measurement and requirements . 34
5.16 Solderability . 34
5.16.1 General . 34
5.16.2 Test procedure . 34
5.16.3 Final inspection, measurements and requirements . 35
5.17 Rapid change of temperature . 35
5.17.1 General . 35
5.17.2 Initial measurements . 35
5.17.3 Test procedures . 35
5.17.4 Final inspection, measurements and requirements . 35
5.18 Vibration . 36
5.18.1 General . 36
5.18.2 Initial measurements . 36
5.18.3 Test procedures . 36
5.18.4 Final inspection, measurements and requirements . 36
5.19 Shock . 36
5.19.1 General . 36

– 4 – IEC 60539-1:2016  IEC 2016
5.19.2 Initial measurements . 36
5.19.3 Mounting . 36
5.19.4 Test procedures . 36
5.19.5 Final inspection, measurements and requirements . 37
5.20 Free fall . 37
5.20.1 General . 37
5.20.2 Initial measurements . 37
5.20.3 Test procedures . 37
5.20.4 Final inspection, measurements and requirements . 37
5.21 Thermal shock . 37
5.21.1 General . 37
5.21.2 Initial measurements . 37
5.21.3 Test procedures . 37
5.21.4 Final inspection, measurements and requirements . 37
5.22 Cold . 38
5.22.1 General . 38
5.22.2 Initial measurements . 38
5.22.3 Test procedures . 38
5.22.4 Final inspection, measurements and requirements . 38
5.23 Dry heat . 38
5.23.1 General . 38
5.23.2 Initial measurements . 38
5.23.3 Test procedures . 39
5.23.4 Final inspection, measurements and requirements . 39
5.24 Damp heat, steady state . 39
5.24.1 General . 39
5.24.2 Initial measurements . 39
5.24.3 Test procedures . 39
5.24.4 Recovery . 40
5.24.5 Final inspection, measurements and requirements . 40
5.25 Endurance . 40
5.25.1 General . 40
5.25.2 Endurance at room temperature with applied continuous maximum
current (I ) (for inrush current-limiting thermistors only) . 40
max25
5.25.3 Endurance at room temperature with applied cyclic maximum current
(I ) (for inrush current-limiting thermistors only) . 41
max25
5.25.4 Endurance at T and P . 42
3 max
5.25.5 Endurance at upper category temperature . 43
5.25.6 Maximum permissible capacitance (for inrush current-limiting
thermistors only) . 43
5.26 Shear (adhesion) test (for surface mount thermistors only) . 45
5.26.1 General . 45
5.26.2 Test conditions . 45
5.26.3 Requirements . 45
5.27 Substrate bending test (for surface mount thermistors only) . 46
5.27.1 General . 46
5.27.2 Initial measurements . 46
5.27.3 Test procedures . 46
5.27.4 Final inspection and requirements . 46
5.28 Component solvent resistance . 46

IEC 60539-1:2016  IEC 2016 – 5 –
5.28.1 General . 46
5.28.2 Initial measurements . 46
5.28.3 Test conditions . 46
5.28.4 Requirements . 47
5.29 Solvent resistance of marking . 47
5.29.1 General . 47
5.29.2 Test conditions . 47
5.29.3 Requirements . 47
5.30 Salt mist . 47
5.30.1 General . 47
5.30.2 Test conditions . 47
5.31 Sealing . 47
5.32 Composite temperature/humidity cycle . 47
5.32.1 General . 47
5.32.2 Initial measurements . 47
5.32.3 Test conditions . 48
5.32.4 Final inspection, measurements and requirements . 48
Annex A (normative) Interpretation of sampling plans and procedures as described in
IEC 60410:1973 for use within quality assessment systems . 49
A.1 Clause and subclause numbers of IEC 60410:1973 . 49
Annex B (normative) Rules for the preparation of detail specifications for directly
heated thermistors for electronic equipment for use within quality assessment systems . 50
B.1 Drafting . 50
B.2 Reference standard . 50
B.3 Circulation . 50
Annex C (informative) Typical examples of mountings for measurements of directly
heated thermistors . 51
C.1 Mounting for surface mount thermistors . 51
Annex D (informative) Reference to IEC 60539-1:2008 . 53
Annex Q (normative) Quality assessment procedures . 54
Q.1 General . 54
Q.2 Primary stage of manufacture . 54
Q.3 Structurally similar components . 54
Q.4 Qualification approval procedures . 55
Q.4.1 General . 55
Q.4.2 Test procedure for qualification approval . 55
Q.4.3 Maintenance of qualification approval . 55
Q.5 Quality conformance inspection . 56
Q.6 Certified test records of released lots . 56
Q.7 Delayed delivery . 56
Q.8 Release for delivery under qualification approval before the completion of
group B tests . 56
Q.9 Alternative test methods . 56
Q.10 Unchecked parameters . 56
Bibliography . 57

Figure 1 – Typical resistance-temperature characteristic for NTC thermistors . 13
Figure 2 – Decreased power dissipation curve . 15
Figure 3 – Maximum current derating . 17

– 6 – IEC 60539-1:2016  IEC 2016
Figure 4 – Basic circuit for zero-power resistance measurement . 24
Figure 5 – Example of Method 1 for testing the insulation resistance . 25
Figure 6 – Example of Method 2 for testing the insulation resistance (1) . 26
Figure 7 – Example of Method 2 for testing the insulation resistance (2) . 26
Figure 8 – Example of Method 3 for testing the insulation resistance . 27
Figure 9 – Example of Method 4 for testing the insulation resistance . 27
Figure 10 – Example of test chamber . 29
Figure 11 – Dissipation factor measuring circuit . 30
Figure 12 – Thermal time constant measuring circuit . 32
Figure 13 – Endurance at room temperature with I evaluating circuit . 41
max25
Figure 14 – Maximum permissible capacitance test circuit (Method 1) . 44
Figure 15 – Maximum permissible capacitance test circuit (Method 2) . 45
Figure C.1 – Mounting for measurements of surface mount thermistors . 52

Table 1 – Lower and upper category temperatures and duration of the damp heat,
steady state test . 20
Table 2 – Tensile force . 33

IEC 60539-1:2016  IEC 2016 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIRECTLY HEATED NEGATIVE TEMPERATURE
COEFFICIENT THERMISTORS –
Part 1: Generic specification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60539-1 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.
This third edition cancels and replaces the second edition published in 2008. This edition
constitutes a technical revision. Tables, figures and references have been revised.
The text of this standard is based on the following documents:
FDIS Report on voting
40/2430/FDIS 40/2457/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.

– 8 – IEC 60539-1:2016  IEC 2016
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60539 series, published under the general title Directly heated
negative temperature coefficient thermistors, 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 website 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.
IEC 60539-1:2016  IEC 2016 – 9 –
DIRECTLY HEATED NEGATIVE TEMPERATURE
COEFFICIENT THERMISTORS –
Part 1: Generic specification
1 Scope
This part of IEC 60539 is applicable to directly heated negative temperature coefficient
thermistors, typically made from transition metal oxide materials with semiconducting
properties.
It establishes standard terms, inspection procedures and methods of test for use in sectional
and detail specifications of electronic components for quality assessment or any other
purpose.
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 60062, Marking codes for resistors and capacitors
IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Tests A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Tests B: Dry heat
IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-11, Basic environmental testing procedures – Part 2-11: Tests – Test Ka: Salt
mist
IEC 60068-2-14, Environmental testing – Part 2-14: Tests – Test N: Change of temperature
IEC 60068-2-17, Basic environmental testing procedures – Part 2-17: Tests – Test Q: Sealing
IEC 60068-2-20, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads
IEC 60068-2-21, Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-31, Environmental testing – Part 2-31: Tests – Test Ec: Rough handling shocks,
primarily for equipment-type specimens
IEC 60068-2-38, Environmental testing – Part 2-38: Tests – Test Z/AD: Composite
temperature/humidity cyclic test

– 10 – IEC 60539-1:2016  IEC 2016
IEC 60068-2-45:1980, Basis Environmental testing procedures – Part 2-45: Tests – Test XA
and guidance: Immersion in cleaning solvents
IEC 60068-2-45:1980/AMD1:1993
IEC 60068-2-52, Environmental testing – Part 2-52: Tests – Test Kb: Salt mist, cyclic (sodium
chloride solution)
IEC 60068-2-54, Environmental testing – Part 2-54: Tests – Test Ta: Solderability testing of
electronic components by the wetting balance method
IEC 60068-2-58, Environmental testing – Part 2-58: Tests – Test Td: Test methods for
solderability, resistance to dissolution of metallization and to soldering heat of surface
mounting devices (SMD)
IEC 60068-2-69, Environmental testing – Part 2-69: Tests – Test Te: Solderability testing of
electronic components for surface mounting devices (SMD) by the wetting balance method
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady
state
IEC 60294, Measurement of the dimensions of a cylindrical component with axial terminations
IEC 61193-2, Quality assessment systems – Part 2: Selection and use of sampling plans for
inspection of electronic components and packages
IEC 60717, Method for the determination of the space required by capacitors and resistors
with unidirectional terminations
IEC 61249-2-7, Materials for printed boards and other interconnecting structures – Part 2-7:
Reinforced base materials clad and unclad – Epoxide woven E-glass laminated sheet of
defined flammability (vertical burning test), copper-clad
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
type
group of products having similar design features manufactured by the same techniques and
falling within the manufacturer's usual range of ratings for these products
Note 1 to entry: Mounting accessories are ignored, provided they have no significant effect on the test results.
Note 2 to entry: Ratings cover the combination of
– electrical ratings,
– sizes, and
– climatic category.
Note 3 to entry: The limits of the range of ratings should be given in the detail specification.
3.2
style
variation within a type having specific nominal dimensions and characteristics

IEC 60539-1:2016  IEC 2016 – 11 –
3.3
thermistor
thermally sensitive semiconducting resistor whose primary function is to exhibit an important
change in electrical resistance with a change in body temperature
3.4
negative temperature coefficient thermistor
NTC thermistor
thermistor in which the resistance decreases with increasing temperature
Note 1 to entry: In general, the term 'NTC thermistor' is used.
3.5
directly heated negative temperature coefficient thermistor
thermistor which obtains its resistance variation by the changes of physical conditions.
Note 1 to entry: Physical conditions include the current through the thermistor, ambient temperature, humidity,
wind velocity, gas, etc.
3.6
indirectly heated negative temperature coefficient thermistor
thermistor which obtains its resistance variation primarily by the change of temperature of the
thermistor, due to the change of a current through a separate heater which is in close contact
with, but electrically insulated from, the thermistor element
Note 1 to entry: The temperature of the thermistor can also be changed by the changes of physical conditions
such as current through the thermistor element itself, ambient temperature, humidity, wind velocity, gas, etc.
Note 2 to entry: This term is for information only.
3.7
positive temperature coefficient thermistor
PTC thermistor
thermistor in which the resistance increases with increasing temperature
Note 1 to entry: In
...