EN IEC 61051-1:2018

Varistors for use in electronic equipment - Part 1: Generic specification

This part of IEC 61051 is a generic specification and is applicable to varistors with symmetrical voltage-current characteristics for use in electronic equipment. It establishes standard terms, inspection procedures and methods of test for use in sectional and detail specifications for quality assessment or any other purpose. NOTE Detail specifications can be specifications within the IEC system, another specification system linked to IEC, or specified by the manufacturer or user. The drafting of a complete detail specification by IEC technical committee 40, if required, follows the rules described in Annex A.

Varistoren zur Verwendung in Geräten der Elektronik - Teil 1: Fachgrundspezifikation

Varistances utilisées dans les équipements électroniques - Partie 1: Spécification générique

La présente partie de l'IEC 61051 est une spécification générique applicable aux varistances à caractéristiques tension-courant symétriques, utilisées dans les équipements électroniques. Elle établit les termes normalisés, les procédures de contrôle et les procédures d'essai utilisés dans les spécifications intermédiaires et particulières à des fins d'assurance de la qualité ou à toute autre fin. NOTE Les spécifications particulières peuvent être des spécifications au sein du système de l'IEC, un autre système de spécifications lié à l'IEC, ou spécifiées par le fabricant ou l'utilisateur. La rédaction d'une spécification particulière complète par le comité d'études 40 de l'IEC, si elle est exigée, suit les règles décrites dans l'Annexe A.

Varistorji za elektronsko opremo - 1. del: Rodovna specifikacija (IEC 61051-1:2018)

Ta del standarda EN 61051 je splošna specifikacija in se uporablja za varistorje s simetričnimi značilnostmi napetostnega toka za uporabo v elektronski opremi.
Določa splošne pogoje, inšpekcijske postopke in preskusne metode za uporabo v sekcijskih in podrobnih specifikacijah za oceno kakovosti ali kateri koli drug namen.
OPOMBA: Podrobne specifikacije so lahko specifikacije v sistemu IEC, drug sistem specifikacij, povezan z IEC,
ali specifikacije, ki jih določi proizvajalec ali uporabnik. Priprava popolne podrobne specifikacije s strani tehničnega odbora IEC 40,
če je potrebna, upošteva pravila, opisana v dodatku A.

General Information

• Status: Published
• Publication Date: 06-Dec-2018
• Withdrawal Date: 02-Dec-2021
• ICS: 31.040.99 - Other resistors
• Technical Committee: CLC/SR 40 - Capacitors and resistors for electronic equipment
• Drafting Committee: IEC/TC 40 - IEC_TC_40
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 07-Dec-2018
• Completion Date: 07-Dec-2018
• Ref Project: SIST EN IEC 61051-1:2019 - Varistors for use in electronic equipment - Part 1: Generic specification (IEC 61051-1:2018)

Relations

• Replaces: EN 61051-1:2008 - Varistors for use in electronic equipment - Part 1: Generic specification
• Effective Date: 23-Aug-2016

Overview

EN IEC 61051-1:2018 (CLC endorsement of IEC 61051-1:2018) is the generic specification for varistors for use in electronic equipment. It establishes standard terminology, preferred characteristics, marking rules and the inspection procedures and test methods that are used in sectional and detail specifications for quality assessment, procurement or manufacturer specifications. The document is intended as the foundation for more detailed product or application-specific specifications within the IEC system or by manufacturers and users.

Key topics and requirements

• Scope and definitions: standard terms and definitions for varistors with symmetrical voltage–current characteristics used in electronic equipment.
• Technical data: units, symbols, preferred values, electrical characteristics (varistor voltage, leakage current, capacitance) and marking/coding requirements.
• Quality assessment procedures: structured approval schemes including qualification approval, capability approval and technology approval, with procedures for application, testing, maintenance and record keeping.
• Manufacturing controls: primary-stage manufacturing rules, subcontracting, treatment of structurally similar components, rework and repair policies, lot release and certified records.
• Test and measurement procedures: general electrical tests, environmental and mechanical test conditions (standard atmospheric conditions, drying/recovery), and specific methods for varistor voltage, leakage, capacitance and voltage-proof testing.
• Environmental and reliability tests: cross-reference to environmental test standards (IEC 60068 series) and EMC/ESD (IEC 61000-4-2) for assessing robustness in real-world conditions.
• Documentation and traceability: requirements for test records, capability reports and maintenance of approvals.

Applications and who uses this standard

• Varistor manufacturers use EN IEC 61051-1 to define product families, internal quality plans and to seek qualification/capability approvals.
• Component procurement teams and OEMs reference this standard in purchase and detail specifications to ensure consistent quality and interchangeability.
• Test laboratories and QA departments implement the standard’s inspection and measurement procedures for incoming/outgoing inspection and failure analysis.
• Design engineers use the defined characteristics (varistor voltage, leakage, capacitance) to select appropriate surge protection components for power supplies, consumer electronics and industrial electronics.

Related standards

Relevant normative references cited in the standard include (examples):

• IEC 60068 series (environmental testing)
• IEC 61000-4-2 (ESD immunity)
• IEC 60695-11-5 (needle/needle-flame test)
  These referenced standards support environmental, mechanical and electrical robustness assessments required by EN IEC 61051-1:2018.

Keywords: EN IEC 61051-1:2018, varistors, varistors for electronic equipment, varistor specification, varistor testing, qualification approval, capability approval, IEC 61051-1, component quality.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2019
1DGRPHãþD
SIST EN 61051-1:2009
Varistorji za elektronsko opremo - 1. del: Rodovna specifikacija (IEC 61051-1:2018)
Varistors for use in electronic equipment - Part 1: Generic specification (IEC 61051-
1:2018)
Varistoren zur Verwendung in Geräten der Elektronik - Teil 1: Fachgrundspezifikation
(IEC 61051-1:2018)
Varistances utilisées dans les équipements électroniques - Partie 1: Spécification
générique (IEC 61051-1:2018)
Ta slovenski standard je istoveten z: EN IEC 61051-1:2018
ICS:
31.040.99 Drugi upori Other resistors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61051-1

NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2018
ICS 31.040.99 Supersedes EN 61051-1:2008
English Version
Varistors for use in electronic equipment - Part 1: Generic
specification
(IEC 61051-1:2018)
Varistances utilisées dans les équipements électroniques - Varistoren zur Verwendung in Geräten der Elektronik - Teil
Partie 1: Spécification générique 1: Fachgrundspezifikation
(IEC 61051-1:2018) (IEC 61051-1:2018)
This European Standard was approved by CENELEC on 2018-12-03. 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, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61051-1:2018 E

European foreword
The text of document 40/2621/FDIS, future edition 3 of IEC 61051-1, 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 IEC 61051-1:2018.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2019-09-03
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2021-12-03
document have to be withdrawn
This document supersedes EN 61051-1:2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61051-1:2018 was approved by CENELEC as a European
Standard without any modification.

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60027 series Letter symbols to be used in electrical EN 60027 series
technology
IEC 60050 series International Electrotechnical Vocabulary - -
IEC 60062 -  Marking codes for resistors and capacitors EN 60062 -
IEC 60068-1 2013 Environmental testing - Part 1: General and EN 60068-1 2014
guidance
IEC 60068-2-1 2007 Environmental testing - Part 2-1: Tests - Test EN 60068-2-1 2007
A: Cold
IEC 60068-2-2 2007 Environmental testing - Part 2-2: Tests - Test EN 60068-2-2 2007
B: Dry heat
IEC 60068-2-6 2007 Environmental testing - Part 2-6: Tests - Test EN 60068-2-6 2008
Fc: Vibration (sinusoidal)
IEC 60068-2-13 1983 Basic environmental testing procedures - Part EN 60068-2-13 1999
2-13: Tests - Test M: Low air pressure
IEC 60068-2-14 2009 Environmental testing - Part 2-14: Tests - Test EN 60068-2-14 2009
N: Change of temperature
IEC 60068-2-20 2008 Environmental testing - Part 2-20: Tests - Test EN 60068-2-20 2008
T: Test methods for solderability and
resistance to soldering heat of devices with
leads
IEC 60068-2-21 2006 Environmental testing - Part 2-21: Tests - Test EN 60068-2-21 2006
U: Robustness of terminations and integral
mounting devices
-
IEC 60068-2-21 2012 Environmental testing - Part 2-21: Tests - Test - -
Corrigendum 1 U: Robustness of terminations and integral
mounting devices; Corrigendum 1
IEC 60068-2-27 2008 Environmental testing - Part 2-27: Tests - Test EN 60068-2-27 2009
Ea and guidance: Shock
IEC 60068-2-30 2005 Environmental testing - Part 2-30: Tests - Test EN 60068-2-30 2005
Db: Damp heat, cyclic (12 h + 12 h cycle)
IEC 60068-2-45 1980 Basic environmental testing procedures - Part EN 60068-2-45 1992
2-45: Tests - Test XA and guidance:
Immersion in cleaning solvents
+A1 1993  - -
IEC 60068-2-58 2015 Environmental testing - Part 2-58: Tests - Test EN 60068-2-58 2015
Td: Test methods for solderability, resistance
to dissolution of metallization and to soldering
heat of surface mounting devices (SMD)
IEC 60068-2-69 2017 Environmental testing - Part 2-69: Tests - Test EN 60068-2-69 2017
Te/Tc: Solderability testing of electronic
components and printed boards by the wetting
balance (force measurement) method
IEC 60068-2-78 2012 Environmental testing - Part 2-78: Tests - Test EN 60068-2-78 2013
Cab: Damp heat, steady state
IEC 60294 -  Measurement of the dimensions of a cylindrical EN 60294 -
component with axial terminations
IEC 60617 -  Graphical symbols for diagrams - -
IEC 60695-11-5 2016 Fire hazard testing - Part 11-5: Test flames - EN 60695-11-5 2017
Needle-flame test method - Apparatus,
confirmatory test arrangement and guidance
IEC 60717 2012 Method for the determination of the space EN 60717 2012
required by capacitors and resistors with
unidirectional terminations
IEC 61000-4-2 2008 Electromagnetic compatibility (EMC) - Part 4-2: EN 61000-4-2 2009
Testing and measurement techniques -
Electrostatic discharge immunity test
IEC 61193-2 -  Quality assessment systems - Part 2: Selection EN 61193-2 -
and use of sampling plans for inspection of
electronic components and packages
IEC 61249-2-7 2002 Materials for printed boards and other EN 61249-2-7 2002
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
- -   + corrigendum Sep. 2005
ISO 80000-1 2009 Quantities and units - Part 1: General EN ISO 80000-1 2013

IEC 61051-1 ®
Edition 3.0 2018-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Varistors for use in electronic equipment –

Part 1: Generic specification
Varistances utilisées dans les équipements électroniques –

Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.040.99 ISBN 978-2-8322-6089-0

– 2 – IEC 61051-1:2018 © IEC 2018
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Technical data . 15
4.1 Units, symbols and terminology . 15
4.2 Preferred values and characteristics . 15
4.3 Marking . 15
4.3.1 General . 15
4.3.2 Coding . 16
5 Quality assessment procedures . 16
5.1 General . 16
5.1.1 Overview . 16
5.1.2 Applicability of qualification approval . 16
5.1.3 Applicability of capability approval . 16
5.1.4 Applicability of technology approval . 17
5.2 Primary stage of manufacture . 17
5.3 Subcontracting . 17
5.4 Structurally similar components . 17
5.5 Qualification approval procedures . 18
5.5.1 Eligibility for qualification approval. 18
5.5.2 Application for qualification approval . 18
5.5.3 Test procedure for qualification approval . 18
5.5.4 Granting of qualification approval . 18
5.5.5 Maintenance of qualification approval . 18
5.5.6 Quality conformance inspection . 18
5.6 Capability approval procedures . 19
5.6.1 General . 19
5.6.2 Eligibility for capability approval . 19
5.6.3 Application for capability approval . 19
5.6.4 Description of capability . 19
5.6.5 Demonstration and verification of capability . 20
5.6.6 Programme for capability approval . 21
5.6.7 Capability approval test report . 21
5.6.8 Abstract of description of capability . 21
5.6.9 Modifications likely to affect the capability approval . 21
5.6.10 Initial capability approval . 21
5.6.11 Granting of capability approval . 22
5.6.12 Maintenance of capability approval . 23
5.6.13 Extension of capability approval . 23
5.6.14 Quality conformance inspection . 23
5.7 Rework and repair . 23
5.7.1 Rework . 23
5.7.2 Repair . 24
5.8 Release for delivery . 24
5.8.1 General . 24

IEC 61051-1:2018 © IEC 2018 – 3 –
5.8.2 Certified records of released lots . 24
5.8.3 Delayed delivery . 24
5.8.4 Release for delivery before the completion of Group B tests . 24
5.9 Alternative test methods . 24
5.10 Unchecked parameters . 25
5.11 Characteristics and parameters for application reference . 25
5.12 Technology approval procedures . 25
5.12.1 General . 25
5.12.2 Eligibility for technology approval . 25
5.12.3 Application of technology approval . 25
5.12.4 Description of technology . 25
5.12.5 Demonstration and verification of the technology . 25
5.12.6 Granting of technology approval . 26
5.12.7 Maintenance of technology approval . 26
5.12.8 Quality conformance inspection . 26
5.12.9 Failure rate level determination . 26
5.12.10 Outgoing quality level . 26
6 Test and measurement procedures . 26
6.1 General . 26
6.2 Standard atmospheric conditions . 26
6.2.1 Standard atmospheric conditions for testing. 26
6.2.2 Recovery conditions . 27
6.2.3 Referee conditions . 27
6.2.4 Reference conditions . 27
6.3 Drying and recovery . 27
6.3.1 General . 27
6.3.2 Procedure I . 27
6.3.3 Procedure II . 27
6.4 Visual examination and check of dimensions . 28
6.4.1 Visual examination . 28
6.4.2 Marking . 28
6.4.3 Dimensions (gauging) . 28
6.4.4 Dimensions (detail) . 28
6.5 General requirements for electrical tests . 28
6.6 Varistor voltage . 29
6.7 Leakage current . 29
6.8 Capacitance . 30
6.9 Voltage proof (for insulated varistors only). 30
6.9.1 General . 30
6.9.2 V-block method . 30
6.9.3 Metal ball method . 30
6.9.4 Foil method . 30
6.10 Insulation resistance (for insulated varistors only) . 31
6.10.1 Test procedure . 31
6.10.2 Measurement and requirements . 31
6.11 Clamping voltage . 31
6.12 ESD clamping voltage (for surface mount electrostatic protective varistors
only) . 32
6.13 Maximum peak current . 32

– 4 – IEC 61051-1:2018 © IEC 2018
6.13.1 Initial measurement . 32
6.13.2 Test procedure . 32
6.13.3 Final inspection, measurement and requirements . 32
6.14 Rated average dissipation power . 32
6.14.1 General . 32
6.14.2 Initial measurement . 33
6.14.3 Test procedure . 33
6.14.4 Final inspection, measurement and requirements . 33
6.15 Rated energy . 33
6.15.1 General . 33
6.15.2 Initial measurement . 33
6.15.3 Test procedure . 34
6.15.4 Final inspection, measurement and requirements . 34
6.16 Electrostatic discharge (ESD) (for surface mount electrostatic protective
varistors only) . 35
6.16.1 Initial measurement . 35
6.16.2 Test procedure . 35
6.16.3 Final inspection, measurement and requirements . 35
6.17 Robustness of terminations . 35
6.17.1 General . 35
6.17.2 Test Ua – Tensile . 35
6.17.3 Test Ub – Bending (half of the number of terminations) . 35
6.17.4 Test Uc – Torsion (the other half of the number of terminations) . 35
6.17.5 Test Ud – Torque (for terminations with threaded studs or screws and for
integral mounting devices) . 36
6.17.6 Visual examination . 36
6.17.7 Final measurement . 36
6.17.8 Robustness of terminations of surface mount varistors . 36
6.18 Resistance to soldering heat . 37
6.18.1 Preconditioning . 37
6.18.2 Test procedure . 37
6.18.3 Recovery . 38
6.18.4 Final inspection, measurement and requirements . 38
6.19 Solderability . 38
6.19.1 General . 38
6.19.2 Test procedure . 38
6.19.3 Final inspection, measurements and requirements . 39
6.20 Rapid change of temperature . 39
6.20.1 Initial measurement . 39
6.20.2 Test procedure . 39
6.20.3 Final inspection, measurement and requirements . 39
6.21 Shock . 39
6.21.1 Initial measurement . 39
6.21.2 Test procedure . 39
6.21.3 Final inspection, measurement and requirements . 39
6.22 Vibration . 40
6.22.1 Initial measurement . 40
6.22.2 Test procedure . 40
6.22.3 Final inspection, measurement and requirements . 40

IEC 61051-1:2018 © IEC 2018 – 5 –
6.23 Climatic sequence . 40
6.23.1 General . 40
6.23.2 Initial measurement . 40
6.23.3 Dry heat . 40
6.23.4 Damp heat, cyclic, Test Db, first cycle . 40
6.23.5 Cold . 40
6.23.6 Low air pressure . 40
6.23.7 Damp heat, cyclic, Test Db, remaining cycles . 41
6.23.8 Final inspection, measurement and requirements . 41
6.24 Damp heat, steady state . 41
6.24.1 Initial measurement . 41
6.24.2 Test procedure . 41
6.24.3 Final inspection, measurement and requirements . 41
6.25 Fire hazard . 42
6.26 Endurance at upper category temperature . 42
6.26.1 Test system . 42
6.26.2 Initial measurement . 42
6.26.3 Mounting of the samples . 42
6.26.4 Test procedure, measurement and requirements . 43
6.27 Solvent resistance of marking . 43
6.27.1 Test procedure . 43
6.27.2 Requirements . 43
6.28 Component solvent resistance . 43
6.28.1 Initial measurements . 43
6.28.2 Test procedure . 43
6.28.3 Measurement and requirements . 44
6.29 Mounting (for surface mount varistors only) . 44
Annex A (informative) Rules for the preparation of detail specifications for capacitors
and resistors for electronic equipment . 46
Annex B (normative) Test pulses used in this specification . 47
B.1 Types of test pulses . 47
B.1.1 General . 47
B.1.2 Pulse type 1 . 47
B.1.3 Pulse type 2 (rectangular pulse) . 47
B.1.4 Pulse type 3 (ESD discharge pulse) . 47
B.2 Pulse parameters . 48
B.2.1 Value of the pulse current/voltage . 48
B.2.2 Virtual front time T . 48
B.2.3 Virtual origin O . 49
B.2.4 Virtual time to half-value T . 49
B.2.5 Virtual duration of peak of a rectangular pulse current T . 49
D
B.2.6 Virtual total duration T of a pulse current . 49
T
B.3 Tolerances for the pulses . 50
Annex C (informative) Recommended measurement/test methods for characteristics
and parameters for application reference . 51
C.1 Voltage vs. current characteristic . 51
C.2 Maximum peak current derating characteristic . 52
C.2.1 Rationale related to this test . 52
C.2.2 Failure criteria . 52

– 6 – IEC 61051-1:2018 © IEC 2018
C.2.3 Pulse life test . 52
C.2.4 Graphing of the maximum peak current derating curves . 54
C.3 Thermal resistance (for leaded varistors only) . 54
C.3.1 Test system . 54
C.3.2 Mounting of the sample . 55
C.3.3 Test procedure . 55
C.4 Abnormal overvoltage withstanding duration . 55
C.4.1 Test system . 55
C.4.2 Test procedure . 56
C.4.3 Requirements . 56

Figure 1 – General scheme for capability approval. 19
Figure 2 – Mounting method for measurement of surface mount varistors . 44
Figure B.1 – Shape of pulse current type 1 . 47
Figure B.2 – Shape of pulse voltage type 1. 48
Figure B.3 – Shape of pulse type 2 . 48
Figure B.4 – Shape of pulse type 3 . 49
Figure C.1 – Maximum peak current derating characteristic . 54

Table 1 – Standard atmospheric conditions . 27
Table 2 – Force for wire terminations . 36
Table 3 – Torque . 36
Table 4 – Number of cycles . 41
Table B.1 – Accepted differences between specified and recorded pulse values . 50
Table B.2 – Tolerances for pulse type 3 . 50

IEC 61051-1:2018 © IEC 2018 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
VARISTORS FOR USE IN ELECTRONIC EQUIPMENT –

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 61051-1 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 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) 10 new terms and definitions – leaded varistors, surface mount varistors(SMV), electrostatic
discharge (ESD), ESD clamping voltage, equivalent rectangular pulse duration, maximum
peak current derating characteristic, rated average dissipation power, rated energy,
abnormal overvoltage withstanding duration and temperature derating curve – have been
added (see 3.6, 3.7, 3.14, 3.15, 3.19, 3.20, 3.23, 3.24, 3.25 and 3.29);
b) General requirements for electrical tests and 7 new test items – clamping voltage, ESD
clamping voltage, maximum peak current, rated average dissipation power, rated energy,
electrostatic discharge (ESD), robustness of terminations of surface mount varistors – have
been added (see 6.5, 6.11, 6.12, 6.13, 6.14, 6.15, 6.16 and 6.17.8);
c) In 6.6, 6.7, 6.8, 6.9.3, 6.23.2, 6.23.4 and 6.26, following test items have been revised:

– 8 – IEC 61051-1:2018 © IEC 2018
• Varistor voltage, leakage current and capacitance: more detailed requirements and
information have been added;
• Voltage proof – foil method: the space between the edge of the foil and each termination
has been changed from 1 mm ~ 1,5 mm to 3 mm ~ 3.5 mm for testing varistors not having
axial terminations and the minimum space between the foil and the termination has been
changed from 1 mm to 3 mm for testing varistors having axial terminations;
• Climatic sequence – dry heat: the method has been changed from Ba to Bb;
• Climatic sequence – cold: the method has been changed from Aa to Ab;
• Endurance at upper category temperature: the method of "applying test voltages in
cycles of 1,5 h on and 0,5 h off" has been changed to the method of applying test voltages
continuously throughout the test lasting for 1 000 h;
d) The test items of pulse current, voltage under pulse condition and bump have been deleted
from the section of test and measurement procedures;
e) Annex A and the contents referring to the test fixture specified in Annex A have been
deleted;
f) All contents related to silicon carbide varistors have been deleted;
g) A new normative annex entitled "Test pulses used in this specification" (Annex B) has been
added;
h) A new informative annex entitled "Recommended measurement/test methods for
characteristics and parameters for application reference" (Annex C) has been added, in
which guidelines of measuring/testing characteristics and parameters for application
reference including voltage vs. current characteristic, maximum peak current derating
characteristic, thermal resistance and abnormal overvoltage withstanding duration have
been given.
The text of this International Standard is based on the following documents:
FDIS Report on voting
40/2621/FDIS 40/2625/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61051 series, published under the general title Varistors for use in
electronic equipment, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC 61051-1:2018 © IEC 2018 – 9 –
VARISTORS FOR USE IN ELECTRONIC EQUIPMENT –

Part 1: Generic specification
1 Scope
This part of IEC 61051 is a generic specification and is applicable to varistors with symmetrical
voltage-current characteristics for use in electronic equipment.
It establishes standard terms, inspection procedures and methods of test for use in sectional
and detail specifications for quality assessment or any other purpose.
NOTE Detail specifications can be specifications within the IEC system, another specification system linked to IEC,
or specified by the manufacturer or user. The drafting of a complete detail specification by IEC technical committee 40,
if required, follows the rules described in Annex A.
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 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050 (all parts), International Electrotechnical Vocabulary (IEV)
IEC 60062, Marking codes for resistors and capacitors
IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Tests B: Dry heat
IEC 60068-2-6:2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (Sinusoidal)
IEC 60068-2-13:1983, Environmental testing – Part 2-13: Tests – Test M: Low air pressure
IEC 60068-2-14:2009, Environmental testing – Part 2-14: Tests – Test N: Change of
temperature
IEC 60068-2-20:2008, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads
IEC 60068-2-21:2006, Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
IEC 60068-2-21:2006/COR1:2012
IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock

– 10 – IEC 61051-1:2018 © IEC 2018
IEC 60068-2-30:2005, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic
(12 h + 12-hour cycle)
IEC 60068-2-45:1980, Envi
...