Fixed inductors for electromagnetic interference suppression - Part 2: Sectional specification

Applies to fixed conductors designed for electromagnetic interference suppression and which fall within the scope of the generic spedification, IEC 60938-1. It is restricted to fixed inductors for which safety tests are appropriate. This implies that inductors specified according to this specification will either be connected to mains supplies, when compliance with the mandatory test of table 1 is necessary, or used in other circuit positions where the equipment specification prescribes that some or all of these safety tests are required. It applies to fixed inductors which will be connected to an a.c. mains or other supply with a nominal voltage not exceeding 1 000 V a.c.(r.m.s.) or d.c. between conductors and with a nominal frequency not exceeding 400 Hz. This consolidated version consists of the second edition (1999) and its amendment 1 (2006). Therefore, no need to order amendment in addition to this publication.

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INTERNATIONAL IEC
STANDARD 60938-2
QC 280100
Edition 2.1
2006-11
Edition 2:1999 consolidated with amendment 1:2006
Fixed inductors for electromagnetic
interference suppression –
Part 2:
Sectional specification
Reference number
IEC 60938-2:1999+A1:2006(E)
---------------------- Page: 1 ----------------------
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
Consolidated editions

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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the

base publication incorporating amendment 1 and the base publication incorporating

amendments 1 and 2.
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---------------------- Page: 2 ----------------------
INTERNATIONAL IEC
STANDARD 60938-2
QC 280100
Edition 2.1
2006-11
Edition 2:1999 consolidated with amendment 1:2006
Fixed inductors for electromagnetic
interference suppression –
Part 2:
Sectional specification
© IEC 2006 ⎯ Copyright - all rights reserved

No part of this publication may be reproduced or utilized in any form or by any means, electronic or

mechanical, including photocopying and microfilm, without permission in writing from the publisher.

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

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

PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 3 ----------------------
– 2 – 60938-2 © IEC:1999+A1:2006(E)
CONTENTS

FOREWORD...........................................................................................................................4

1 General ............................................................................................................................6

1.1 Scope......................................................................................................................6

1.2 Object .....................................................................................................................6

1.3 Normative references ..............................................................................................6

1.4 Information to be given in a detail specification ........................................................7

1.5 Definitions ...............................................................................................................8

1.6 Marking ...................................................................................................................8

2 Preferred ratings and characteristics.................................................................................8

2.1 Climatic categories ..................................................................................................8

2.2 Values of ratings......................................................................................................9

3 Quality assessment procedures ........................................................................................9

3.1 Primary stage of manufacture ..................................................................................9

3.2 Structurally similar inductors ....................................................................................9

3.3 Certified records of released lots ...........................................................................10

3.4 Qualification approval ............................................................................................10

3.5 Quality conformance inspection .............................................................................14

4 Test and measurement procedures .................................................................................14

4.1 Visual examination and check of dimensions..........................................................14

4.2 Voltage proof.........................................................................................................15

4.3 Insulation resistance..............................................................................................15

4.4 Inductance.............................................................................................................16

4.5 DC line resistance .................................................................................................16

4.6 Robustness of terminations....................................................................................16

4.7 Resistance to soldering heat..................................................................................16

4.8 Solderability...........................................................................................................16

4.9 Rapid change of temperature.................................................................................16

4.10 Vibration................................................................................................................17

4.11 Bump ....................................................................................................................17

4.12 Shock....................................................................................................................18

4.13 Container sealing...................................................................................................18

4.14 Climatic sequence .................................................................................................18

4.15 Damp heat, steady state ........................................................................................19

4.16 Temperature rise (applies only to inductors with a mass >5 g)................................19

4.17 Impulse voltage (applies to inductors with more than one winding) .........................20

4.18 Endurance.............................................................................................................21

4.19 Passive flammability (if applicable) ........................................................................22

4.20 Component solvent resistance (if applicable) .........................................................22

4.21 Solvent resistance of marking (if applicable) ..........................................................22

Annex A (normative) Test schedule for safety tests only approval........................................23

Annex B (normative) Test schedule for safety tests and performance tests

for qualification approval, assessment level D .......................................................................26

Annex C (normative) Example of a suitable circuit for the endurance test voltage ................31

Annex D (normative) Declaration of design (confidential to the manufacturer

and the certification body) .....................................................................................................32

Annex E (normative) Test methods for thyristor electromagnetic

interference suppression inductors ........................................................................................33

---------------------- Page: 4 ----------------------
60938-2 © IEC:1999+A1:2006(E) – 3 –

Figure C.1 – Endurance test circuit........................................................................................31

Figure E.1 – Test circuit for temperature rise.........................................................................33

Figure E. 2 – Test circuit for interference voltage attenuation.................................................34

Table 1 – Sampling plan for safety tests only.........................................................................12

Table 2 – Sampling plan for safety tests and performance tests, assessment level D .............13

Table 3 – Measuring points ...................................................................................................15

Table 4 – Acceleration...........................................................................................................17

Table 5 – Sweep cycles.........................................................................................................17

Table 6 – Preferred severities ...............................................................................................18

---------------------- Page: 5 ----------------------
– 4 – 60938-2 © IEC:1999+A1:2006(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIXED INDUCTORS FOR ELECTROMAGNETIC
INTERFERENCE SUPPRESSION –
Part 2: Sectional 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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

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

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60938-2 has been prepared by IEC technical committee 40:

Capacitors and resistors for electronic equipment.

This consolidated version of IEC 60938-2 consists of the second edition (1999) [documents

40/1111/FDIS and 40/1137/RVD] and its amendment 1 (2006) [documents 40/1603/CDV and

40/1700A/RVC].

The technical content is therefore identical to the base edition and its amendment and has

been prepared for user convenience.
It bears the edition number 2.1.

A vertical line in the margin shows where the base publication has been modified by

amendment 1.

The QC number that appears on the front cover of this publication is the specification number

in the IEC Quality Assessment System for Electronic Components (IECQ).
---------------------- Page: 6 ----------------------
60938-2 © IEC:1999+A1:2006(E) – 5 –
Annexes A, B, C, D and E form an integral part of this standard.

The committee has decided that the contents of the base publication and its amendments will

remain unchanged until the maintenance result 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.
A bilingual version of this publication may be issued at a later date.
---------------------- Page: 7 ----------------------
– 6 – 60938-2 © IEC:1999+A1:2006(E)
FIXED INDUCTORS FOR ELECTROMAGNETIC
INTERFERENCE SUPPRESSION –
Part 2: Sectional specification
1 General
1.1 Scope

This International Standard applies to fixed inductors designed for electromagnetic interference

suppression and which fall within the scope of the generic specification, IEC 60938-1. It is

restricted to fixed inductors for which safety tests are appropriate. This implies that inductors

specified according to this specification will either be connected to mains supplies, when

compliance with the mandatory tests of table 1 is necessary, or used in other circuit positions

where the equipment specification prescribes that some or all of these safety tests are required.

This standard applies to fixed inductors which will be connected to an a.c. mains or other

supply with a nominal voltage not exceeding 1 000 V a.c. (r.m.s.) or d.c. between conductors

and with a nominal frequency not exceeding 400 Hz.
1.2 Object

The object of this standard is to prescribe standard requirements for safety tests and standard

ratings and characteristics, to select from IEC 60938-1 the appropriate methods of test and to

give general performance requirements for suppression inductors. Test severities and

performance requirements prescribed in detail specifications referring to this sectional

specification shall be of equal or higher performance level. In addition, the minimum require-

ments for safety tests specified herein always apply.
1.3 Normative references

Les documents de référence suivants sont indispensables pour l'application du présent

document. Pour les références datées, seule l'édition citée s'applique. Pour les références non

datées, la dernière édition du document de référence s'applique (y compris les éventuels

amendements).

IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test requirements

IEC 60063:1963, Preferred number series for resistors and capacitors
Amendment 1 (1967)
Amendment 2 (1977)
IEC 60085:1984, Thermal evaluation and classification of electrical insulation

IEC 60279:1969, Measurement of the winding resistance of an a.c. machine during operation at

alternative voltage

IEC 60938-1:1999, Fixed inductors for electromagnetic interference suppression – Part 1:

Generic specification
ISO 3:1973, Preferred numbers – Series of preferred numbers

CISPR 16-1-1:2003, Specification for radio disturbance and immunity measuring apparatus and

methods – Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring

apparatus
---------------------- Page: 8 ----------------------
60938-2 © IEC:1999+A1:2006(E) – 7 –
1.4 Information to be given in a detail specification
1.4.1 General

Detail specifications shall be derived from the relevant blank detail specification.

Detail specifications shall not specify requirements inferior to those of the generic or sectional

specification. When more severe requirements are included they shall be listed in 1.8 of the

detail specification and indicated in the test schedules, for example by an asterisk.

NOTE The information given in 1.4.2 may, for convenience, be presented in tabular form.

The information given in 1.4.2 to 1.4.5 shall be given in each detail specification and the values

quoted shall preferably be selected from those given in the appropriate clause of this sectional

specification.
1.4.2 Outline drawing and dimensions

There shall be an illustration of the inductor as an aid to easy recognition and for comparison

of the inductor with others. Dimensions and their associated tolerances, which affect

interchangeability and mounting, shall be indicated upon the drawing. All dimensions shall be

stated in millimetres.

Normally the numerical values shall be given for the length of the body, the width and height of

the body or for cylindrical types, the body diameter, and the length and diameter of the

terminations. When necessary, for example when a number of items (inductance values/

voltage ranges) are covered by a detail specification, the dimensions and their associated

tolerances shall be placed in a table below the drawing.

When the configuration is other than described above, the detail specification shall state such

dimensional information as will adequately describe the inductor. When the inductor is not

designed for use on printed boards, this shall be clearly stated in the detail specification.

1.4.3 Mounting

The detail specification shall specify the method of mounting to be recommended for normal

use and the method which is mandatory for the application of the vibration, bump and shock

tests. The design of the inductor may be such that special mounting fixtures are required in its

use. In this case, the detail specification shall describe the mounting fixtures and they shall be

used in the application of the bump, shock and vibration tests. The specified heat sink shall

be used in the application of the endurance test.
1.4.4 Ratings and characteristics

The ratings and characteristics shall be in accordance with the relevant clauses of this

specification.

1.4.4.1 Additional characteristics may be listed, when they are considered necessary to

specify adequately the inductor for design and application purposes.
1.4.5 Marking

Deviations from 1.6 of this sectional specification, shall be specifically stated in the detail

specification.
---------------------- Page: 9 ----------------------
– 8 – 60938-2 © IEC:1999+A1:2006(E)
1.5 Definitions

For the purpose of this International Standard, the definitions in IEC 60938-1 apply.

1.6 Marking

1.6.1 The information given in the marking is normally selected from the following list; the

relative importance of each item is indicated by its position in the list:
a) manufacturer's name (or trade mark);
b) manufacturer's type designation;
c) recognized approval mark;
d) rated inductance and tolerance;
e) rated voltage;
f) rated current;
g) identification of terminations or circuit diagram;
h) rated temperature;
i) climatic category;
j) year and month (or week) of manufacture (this may be in code form);
k) reference to the detail specification.

1.6.2 Marking of the inductor may be omitted when the manufacturer considers that there is

insufficient space, and this fact is recorded in the detail specification. When present, the

marking shall be sufficient to provide a clear identification of the inductor. Any duplication of

information in the marking on the inductor should be avoided.

1.6.3 The packaging containing the inductor(s) shall be clearly marked with all the information

listed in 1.6.1, except g).
1.6.4 Any additional marking shall be so applied that no confusion can arise.
2 Preferred ratings and characteristics
2.1 Climatic categories

Electromagnetic interference suppression inductors covered by this specification are classified

into climatic categories according to the general rules given in IEC 60068-1. The lower and

upper category temperatures and the duration of the damp heat, steady state test shall be

selected from the following:
Lower category temperature: –65 °C, –55 °C, –40 °C, –25 °C and –10 °C.
Upper category temperature: +85 °C, +100 °C, +125 °C and +155 °C.
Duration of the damp heat, steady state test: 21 and 56 days.

The severities for the cold and dry heat tests are the lower and upper category temperatures

respectively.
---------------------- Page: 10 ----------------------
60938-2 © IEC:1999+A1:2006(E) – 9 –
2.2 Values of ratings
2.2.1 Rated inductance and tolerance

Preferred values of rated inductance are values chosen from the E 6 series of preferred values

given in IEC 60063.
The preferred tolerances on rated inductance are as follows:
±30 %; –30 %/+50 %.
2.2.2 Rated voltage (U )
Preferred values for rated voltages are:
AC inductors: 50 V, 125 V, 250 V, 400 V, 440 V, 480 V and 760 V.
DC inductors: 50 V, 160 V, 250 V and 500 V.

NOTE Electromagnetic interference suppression inductors are normally chosen to have their rated voltage equal

to or greater than the nominal voltage of the supply system to which they are to be connected. It should, however,

be borne in mind that the voltage of the system may rise up to 10 % above the nominal voltage.

2.2.3 Category voltage (U )

The category voltage is equal to the rated voltage, unless otherwise stated in the detail

specification.
2.2.4 Rated temperature
The rated temperature shall not be lower than +40 °C.
2.2.5 Rated current
The preferred values of rated current are selected from the R10 series of ISO 3.
2.2.6 Passive flammability

When specified, the minimum category of passive flammability permitted is category C.

3 Quality assessment procedures
3.1 Primary stage of manufacture
See 3.2 of IEC 60938-1.
3.2 Structurally similar inductors

Inductors are structurally similar when for their range of inductance values they have the

following common characteristics:
a) essentially the same materials;
b) similar design features and manufacturing techniques;
c) same rated voltage.
---------------------- Page: 11 ----------------------
– 10 – 60938-2 © IEC:1999+A1:2006(E)
3.3 Certified records of released lots

When certified test records are requested by a purchaser, they shall be specified in the detail

specification.
3.4 Qualification approval

The procedures for qualification approval testing for structurally similar inductors are given

in 3.4 of IEC 60938-1.
3.4.1 Qualification approval on the basis of the fixed sample size procedures
3.4.1.1 Sampling

This standard covers procedures for qualification approval tests only. Two alternative test

procedures are given, namely the full test procedure covering both safety tests and

performance requirements, and a restricted test procedure covering safety tests.

Table 1 and annex A form the schedule limited to tests for safety tests only approval. Prior to

the approval testing for safety tests only it is necessary to submit to the certification body a

declaration of design (annex D) registering essential data and basic design details of the

inductors for which approval is sought.

Table 2 and annex B form the full schedule for safety tests and performance approval.

Each rated voltage shall be separately qualified. The total number of inductors of each rated

voltage to be tested in each group is given in table 1 or 2. For each rated voltage the sample

shall contain equal numbers of specimens of the highest and lowest inductance and the highest

and lowest rated current in the range to be qualified. Where only one inductance value or rated

current value is involved, the total number of inductors as stated in table 1 or 2 shall be tested.

Spare specimens are permitted as follows:

a) one per inductance/rated current combination which may be used to replace the permitted

non-conforming items in group 0;

b) one per inductance/rated current combination which may be used as replacements for

specimens lost due to incidents not attributable to the manufacturer or the test sequence;

c) the remainder of the spares may be required if it is necessary to repeat any test according

to the provisions of note 1 to table 1 or 2;

d) spares may be kept at the premises of the manufacturer instead of being sent to the testing station.

The number of samples given in group 0 assume that all groups are applicable. If this is not so

the numbers may be reduced accordingly.

When additional groups are introduced into the qualification approval test schedule, the

number of specimens required for group 0 shall be increased by the same number as that

required for the additional groups.
---------------------- Page: 12 ----------------------
60938-2 © IEC:1999+A1:2006(E) – 11 –
3.4.1.2 Tests

The complete series of tests specified in either table 1 or 2 is required for the approval of a

series of structurally similar inductors of one rated voltage. The tests of each group shall be

carried out in the order given.

The whole sample shall be subjected to the tests of group 0 and then divided for the other groups.

Non-conforming items found during the tests of group 0 shall not be used for the other groups.

"One non-conforming item" is counted when an inductor has not satisfied the whole or part of

the tests of a group.

The approval is granted when the number of non-conformances does not exceed the specified

number of permissible non-conforming items for each group or subgroup and the total number

of permissible non-conformances indicated in table 1 or 2.

NOTE Table 1 and annex A or table 2 and annex B together form the fixed sample size test schedule, for which

table 1 or 2 includes the details for the sampling and permissible non-conforming items for the different tests or

groups of tests, whereas annexes A or B together with the details of test contained in clause 4 give a complete

summary of test conditions and performance requirements and indicate where, for example for the test method or

conditions of test, a choice has to be made in the detail specification. The conditions of test and performance

requirements for the fixed sample size test schedule shall be identical to those prescribed in the detail

specification.
---------------------- Page: 13 ----------------------
– 12 – 60938-2 © IEC:1999+A1:2006(E)
Table 1 – Sampling plan for safety tests only
Group Test Subclause Number of specimens Number of permissible
of this tested per rated voltage non-conforming items
publication and for each mass per rated voltage
group (2)
Per group Total
n c c
0 Visual examinations 4.1
Line resistance 4.5 1
Inductance 4.4 40/22/10/5
Voltage proof 4.2
Insulation resistance 4.3
Spares 4/2/2/1
1A Dimensions (detail) 4.1.2
Creepage distances and
clearances 4.1.2 10/6/2/1 0
Robustness of terminations 4.6
Resistance to soldering
heat (1) 4.7
Component solvent
resistance (if applicable) (5) 4.20
2 Damp heat, steady state 4.15 18/10/4/2 0 0
Temperature rise (3) 4.16
3A or or
Endurance current (4) 4.18
3B Impulse voltage (7)(8) 4.17 12/6/4/2 0
Endurance voltage 4.18
between line termina-
tions (7)
4 Passive flammability (5) 4.19 see 4.19 0
NOTES to tables 1 and 2:
NOTE 1 If applicable.
NOTE 2 The number of specimens indicated relate to the mass limits as follows:
≤5 g
>5 g and ≤250 g
>250 g and ≤1 500 g
>1 500 g respectively.

Where a range is qualified which contains inductors within more than one of the mass classifications listed

above, the number of specimens selected shall be that for the classification in which the majority of the values

in the range fall.
The numbers in group 0 exclude the numbers of specimens required fo
...

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