IEC 63093-11:2018

Ferrite cores - Guidelines on dimensions and the limits of surface irregularities - Part 11: EC-cores for use in power supply applications

IEC 63093-11:2018 specifies the dimensions that are of importance for mechanical interchangeability for a preferred range of EC-cores made of ferrite and the essential dimensions of coil formers to be used with them, as well the effective parameter values to be used in calculations involving them. It also gives guidelines on allowable limits of surface irregularities applicable to EC-cores.
The specifications contained in this document are useful in negotiations between ferrite core manufacturers and customers about surface irregularities.
This first edition cancels and replaces the first edition of IEC 62317-11 published in 2015 and the second edition of IEC 60424-3 published in 2015. This edition constitutes a technical revision.
This document includes the following significant technical changes with respect to IEC 62317­11:2015 and IEC 60424-3:2015:
a) This document integrates IEC 62317-11:2015 and IEC 60424­3:2015;
b) Table 3 – Allowable areas of chips for EC-cores, of IEC 60424-3:2015, has been moved to Annex B (informative) of this document.

Noyaux ferrites - Lignes directrices relatives aux dimensions et aux limites des irrégularités de surface - Partie 11: Noyaux EC destinés aux applications d’alimentation électrique

L’IEC 63093-11:2018 spécifie les dimensions importantes pour l’interchangeabilité mécanique d’une plage préférentielle de noyaux EC en matériaux ferrites et les dimensions essentielles des supports de bobines à utiliser avec, ainsi que les valeurs des paramètres effectifs destinées aux calculs les impliquant. Elle donne également les lignes directrices relatives aux limites admissibles des irrégularités de surface applicables aux noyaux EC.
Les spécifications du présent document sont utiles au dialogue entre les fabricants de noyaux en ferrite et leurs clients sur les irrégularités de surface.Cette première édition annule et remplace la première édition de l’IEC 62317-11 parue en 2015 et la deuxième édition de l’IEC 60424-3 parue en 2015. Cette édition constitue une révision technique.
Ce document inclut les modifications techniques majeures suivantes par rapport à l'IEC 62317­11:2015 et à l’IEC 60424-3:2015:
a) ce document intègre l’IEC 62317-11:2015 et l’IEC 60424­3:2015;
b) le Tableau 3 – Surfaces admissibles des éclats pour les noyaux EC, de l’IEC 60424-3:2015, a été déplacé à l’Annexe B (informative) de ce document.

General Information

• Status: Published
• Publication Date: 20-Jun-2018
• ICS: 29.100.10 - Magnetic components
• Technical Committee: TC 51 - Magnetic components, ferrite and magnetic powder materials
• Drafting Committee: WG 1 - TC 51/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 21-Jun-2018
• Completion Date: 23-Jul-2018

Relations

• Replaces: IEC 60424-3:2015 - Ferrite cores - Guidelines on the limits of surface irregularities - Part 3: ETD-cores, EER-cores, EC-cores and E-cores
• Effective Date: 05-Sep-2023
• Replaces: IEC 62317-11:2015 - Ferrite cores - Dimensions - Part 11: EC-cores for use in power supply applications
• Effective Date: 05-Sep-2023

Overview - IEC 63093-11:2018 (Ferrite cores - EC‑cores for power supplies)

IEC 63093-11:2018 is an International Electrotechnical Commission standard that specifies mechanical dimensions, effective magnetic parameters, and allowable surface irregularities for a preferred range of EC‑cores made of ferrite used in power‑supply applications. It ensures mechanical interchangeability of complete core assemblies and coil formers and provides practical guidance for negotiations between ferrite core manufacturers and customers. This edition integrates and replaces IEC 62317‑11:2015 and IEC 60424‑3:2015.

Key topics and technical requirements

• Principal dimensions and tolerances: Defines the essential geometric dimensions for EC‑core sizes (EC 35 through EC 120) to ensure mechanical interchangeability of cores and coil formers.
• Effective parameters (Amin, leakage, volumes): Provides effective parameter values to be used in calculations (see IEC 60205 for parameter definitions and calculation methods). Manufacturers may publish more precise values in catalogues.
• Coil former limits: Specifies essential dimensional limits for compatible coil formers and includes example coil former designs (Annex A).
• Surface irregularities and visual acceptance criteria: Gives definitions and limits for common defects - chips, ragged edges, cracks, flash, pull‑outs, crystallites and pores:
  • Minimum visually distinguishable chip area is 0.5 mm², maximum allowable single area 25 mm².
  • For chips on mating surfaces: cumulative chip area must be < 6% of the mating surface area; total length of ragged edges < 25% of the surface perimeter.
  • Illustrative figures, inspection references and tables for crack limits and pore locations are included.
• Annexes: Annex A provides coil former examples; Annex B (informative) contains allowable areas of chips.

Practical applications - who uses this standard

• Ferrite core manufacturers - to design and certify EC‑cores and produce consistent dimensional data and visual acceptance criteria.
• Power supply designers and magnetic component engineers - to select interchangeable EC‑cores, specify coil formers and use the effective parameters in electromagnetic calculations.
• Quality assurance and procurement teams - to define acceptance criteria, perform visual inspections, and negotiate supply contracts based on standardized limits for surface irregularities.
• Test labs and certification bodies - to verify compliance with dimensional and surface defect limits.

Related standards and references

• IEC 60205 - Calculation of effective parameters of magnetic piece parts (parameter definitions and methods).
• IEC 60401‑1 - Terms and nomenclature for ferrite cores (physical irregularities).
• IEC 60424‑1 - General specification for limits of surface irregularities.

Keywords: IEC 63093‑11:2018, EC‑cores, ferrite cores, power supply applications, surface irregularities, dimensions, coil formers, effective parameters, mechanical interchangeability.

Standards Content (Sample)

IEC 63093-11 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
Ferrite cores – Guidelines on dimensions and the limits of surface
irregularities –
Part 11: EC-cores for use in power supply applications

All rights reserved. Unless otherwise specified, 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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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IEC Central Office Tel.: [phone]
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
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IEC 63093-11 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
Ferrite cores – Guidelines on dimensions and the limits of surface

irregularities –
Part 11: EC-cores for use in power supply applications

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.100.10 ISBN 978-2-8322-5832-3

– 2 – IEC 63093-11:2018 © IEC 2018
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Primary dimensions . 5
4.1 General . 5
4.2 Dimensions of EC-cores. 6
4.2.1 Principal dimensions . 6
4.2.2 Effective parameter and A values . 6
min
4.3 Dimensional limits for coil formers. 8
5 Limits of surface irregularities . 8
5.1 General . 8
5.2 Examples of surface irregularities . 8
5.3 Chips and ragged edges . 9
5.3.1 General. 9
5.3.2 Chips and ragged edges on the mating surfaces . 9
5.3.3 Chips and ragged edges on the other surfaces . 9
5.4 Cracks . 12
5.5 Flash . 12
5.6 Pull-outs . 12
5.7 Crystallites . 13
5.8 Pores . 13
Annex A (normative) Example of standard coil formers . 15
Annex B (informative) Reference of allowable areas of chips . 17
Bibliography . 18

Figure 1 – Dimensions of EC-cores . 6
Figure 2 – Main dimensions of coil formers for EC-cores. 8
Figure 3 – Examples of surface irregularities . 9
Figure 4 – Chip location for EC-cores . 10
Figure 5 – Crack and pull-out locations for EC-cores . 12
Figure 6 – Crystallite location for EC-cores . 13
Figure 7 – Pore location for EC-cores . 14
Figure A.1 – Main dimensions of coil formers for EC 35, EC 41, EC 52, EC 70 cores . 15
Figure A.2 – Main dimensions of coil formers for EC 90 core . 15

Table 1 – Dimensions of EC-cores . 7
Table 2 – Effective parameter and A values . 7
min
Table 3 – Dimensional limits for coil formers . 8
Table 4 – Area and length reference for visual inspection . 11
Table 5 – Limits for cracks . 13
Table A.1 – Main dimensions of coil formers (examples from Figures A.1 and A.2) for
EC-cores . 16
Table B.1 – Allowable areas of chips for EC-cores . 17

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FERRITE CORES – GUIDELINES ON DIMENSIONS
AND THE LIMITS OF SURFACE IRREGULARITIES –

Part 11: EC-cores for use in power supply applications

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
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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.
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7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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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 63093-11 has been prepared by IEC technical committee 51:
Magnetic components, ferrite and magnetic powder materials.
This first edition cancels and replaces the first edition of IEC 62317-11 published in 2015 and
the second edition of IEC 60424-3 published in 2015. This edition constitutes a technical
revision.
This document includes the following significant technical changes with respect to
IEC 62317-11:2015 and IEC 60424-3:2015:
a) This document integrates IEC 62317-11:2015 and IEC 60424-3:2015;
b) Table 3 – Allowable areas of chips for EC-cores, of IEC 60424-3:2015, has be
...

IEC 63093-11 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ferrite cores – Guidelines on dimensions and the limits of surface irregularities –
Part 11: EC-cores for use in power supply applications

Noyaux ferrites – Lignes directrices relatives aux dimensions et aux limites
des irrégularités de surface –
Partie 11: Noyaux EC destinés aux applications d’alimentation électrique
All rights reserved. Unless otherwise specified, 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
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

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IEC 63093-11 ®
Edition 1.0 2018-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ferrite cores – Guidelines on dimensions and the limits of surface irregularities –

Part 11: EC-cores for use in power supply applications

Noyaux ferrites – Lignes directrices relatives aux dimensions et aux limites

des irrégularités de surface –

Partie 11: Noyaux EC destinés aux applications d’alimentation électrique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.100.10 ISBN 978-2-8322-6203-0

– 2 – IEC 63093-11:2018 © IEC 2018
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Primary dimensions . 5
4.1 General . 5
4.2 Dimensions of EC-cores. 6
4.2.1 Principal dimensions . 6
4.2.2 Effective parameter and A values . 6
min
4.3 Dimensional limits for coil formers. 8
5 Limits of surface irregularities . 8
5.1 General . 8
5.2 Examples of surface irregularities . 8
5.3 Chips and ragged edges . 9
5.3.1 General. 9
5.3.2 Chips and ragged edges on the mating surfaces . 9
5.3.3 Chips and ragged edges on the other surfaces . 9
5.4 Cracks . 12
5.5 Flash . 12
5.6 Pull-outs . 12
5.7 Crystallites . 13
5.8 Pores . 13
Annex A (normative) Example of standard coil formers . 15
Annex B (informative) Reference of allowable areas of chips . 17
Bibliography . 18

Figure 1 – Dimensions of EC-cores . 6
Figure 2 – Main dimensions of coil formers for EC-cores. 8
Figure 3 – Examples of surface irregularities . 9
Figure 4 – Chip location for EC-cores . 10
Figure 5 – Crack and pull-out locations for EC-cores . 12
Figure 6 – Crystallite location for EC-cores . 13
Figure 7 – Pore location for EC-cores . 14
Figure A.1 – Main dimensions of coil formers for EC 35, EC 41, EC 52, EC 70 cores . 15
Figure A.2 – Main dimensions of coil formers for EC 90 core . 15

Table 1 – Dimensions of EC-cores . 7
Table 2 – Effective parameter and A values . 7
min
Table 3 – Dimensional limits for coil formers . 8
Table 4 – Area and length reference for visual inspection . 11
Table 5 – Limits for cracks . 13
Table A.1 – Main dimensions of coil formers (examples from Figures A.1 and A.2) for
EC-cores . 16
Table B.1 – Allowable areas of chips for EC-cores . 17

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FERRITE CORES – GUIDELINES ON DIMENSIONS
AND THE LIMITS OF SURFACE IRREGULARITIES –

Part 11: EC-cores for use in power supply applications

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 63093-11 has been prepared by IEC technical committee 51:
Magnetic components, ferrite and magnetic powder materials.
This bilingual version (2018-11) corresponds to the monolingual English version, published in
2018-06.
This first edition cancels and replaces the first edition of IEC 62317-11 published in 2015 and
the second edition of IEC 60424-3 published in 2015. This edition constitutes a technical
revision.
This document includes the following significant technical changes with respect to
IEC 62317-11:2015 and IEC 60424-3:2015:
a) This document integrates IEC 62317-11:2015 and IEC 60424-3:2015;

– 4 – IEC 63093-11:2018 © IEC 2018
b) Table 3 – Allowable areas of chips for EC-cores, of IEC 60424-3:2015, has been moved to
Annex B (informative) of this document.
The text of this International Standard is based on the following documents:
CDV Report on voting
51/1214/CDV 51/1236/RVC
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.
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 63093 series, published under the general title Ferrite cores –
Guidelines on dimensions and the limits of surface irregularities, 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.
FERRITE CORES – GUIDELINES ON DIMENSIONS
AND THE LIMITS OF SURFACE IRREGULARITIES –

Part 11: EC-cores for use in power supply applications

1 Scope
This part of IEC 63093 specifies the dimensions that are of importance for mechanical
interchangeability for a preferred range of EC-cores made of ferrite and the essential
dimensions of coil formers to be used with them, as well the effective parameter values to be
used in calculations involving them. It also gives guidelines on allowable limits of surface
irregularities applicable to EC-cores.
The specifications contained in this document are useful in negotiations between ferrite core
manufacturers and customers about surface irregularities.
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 60205, Calculation of the effective parameters of magnetic piece parts
IEC 60401-1, Terms and nomenclature for cores made of magnetically soft ferrites – Part 1:
Terms used for physical irregularities
IEC 60424-1, Ferrite cores – Guidelines on the limits of surface irregularities – Part 1:
General specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60401-1 and
IEC 60424-1 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
4 Primary dimensions
4.1 General
Compliance with the following requirements ensures mechanical interchangeability of
complete assemblies and coil formers.

– 6 – IEC 63093-11:2018 © IEC 2018
4.2 Dimensions of EC-cores
4.2.1 Principal dimensions
The principal dimensions of EC-cores shall be those given in Figure 1 and Table 1.
values
4.2.2 Effective parameter and A
min
The effective parameter values of a pair of cores whose dimensions comply with 4.2.1 shall
be as given in Table 2. For the definitions of these parameters and their calculations,
reference shall be made to IEC 60205.
B C
s
r
r
D
IEC
Figure 1 – Dimensions of EC-cores

A
F
E
T
Table 1 – Dimensions of EC-cores
A B C D E F r s T
Size mm mm mm mm mm mm mm mm mm
Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Max. Min. Max. Min. Max.
EC 35 33,7 35,3 17,15 17,45 9,2 9,8 11,9 12,6 22,2 23,3 9,2 9,8 0,5 2,5 3,0 27,7 29,3
EC 41 39,6 41,6 19,35 19,65 11,3 11,9 13,5 14,3 26,3 27,8 11,3 11,9 0,7 3,0 3,3 32,6 34,6
EC 52 50,9 53,5 24,05 24,35 13,05 13,75 15,5 16,3 32,1 33,9 13,05 13,75 0,8 3,5 4,0 42,7 45,3
EC 70 68,3 71,7 34,35 34,65 16,0 16,8 22,3 23,2 43,3 45,7 16,0 16,8 1,0 4,5 5,0 57,9 61,3
EC 90 88,2 91,8 44,35 45,65 29,0 31,0 35,0 36,0 68,5 71,5 29,0 31,0 1,0 5,2 5,8 77,2 80,8
EC 120 118,0 122,0 49,85 51,15 29,0 31,0 35,0 36,0 93,3 96,7 29,0 31,0 1,5 5,2 5,8 107,0 111,0

Table 2 – Effective parameter and A values
min
a
C C l A V A
1 2 e e e min
Size
-1 -3 2 3 2
mm mm mm mm mm mm
-3
EC 35 0,857 84 9,490 2 × 10 77,5 90,4 7 010 70,9
-3
EC 41 0,718 10 5,851 9 × 10 88,1 123 10 800 106
-3
EC 52 0,572 11 103 181 18 600 141
3,168 9 × 10
-3
EC 70 0,508 60 142 280 39 800 211
1,818 5 × 10
-3
EC 90 0,342 51 0,544 66 × 10 215 629 135 000 570
-3
EC 120 0,324 96 251 772 194 000 707
0,420 96 × 10
NOTE Manufacturers can indicate more precise values in their catalogues than those given in Table 2.
a
A is specified in IEC 60205.
min
– 8 – IEC 63093-11:2018 © IEC 2018
4.3 Dimensional limits for coil formers
The essential dimensions of coil formers suitable for use with a pair of EC-cores shall be as
given in Table 3. The dimensions specified in Table 3 are illustrated in Figure 2.
Examples of standard coil formers are shown in Annex A.
h
h
IEC
Figure 2 – Main dimensions of coil formers for EC-cores
Table 3 – Dimensional limits for coil formers
d d d h h
1 2 3 1 2
Size mm mm mm mm mm
Max. Max. Min. Max. Min.
EC 35 21,8 12,3 9,9 23,6 21,4
EC 41 25,8 14,4 12,0 26,8 24,4
EC 52 31,6 16,3 13,85 30,7 28,2
EC 70 42,7 19,6 17,0 44,3 41,3
EC 90 67,7 35,6 31,4 69,6 64,8
EC 120 92,4 35,6 31,4 69,6 64,8

5 Limits of surface irregularities
5.1 General
Surface irregularities are defined in IEC 60424-1.
5.2 Examples of surface irregularities
Figure 3 shows different examples of surface irregularities of an EC-core.
d
d
d
Cracks
Flash
Ragged
edge
Pull-out
Crystallite
Chip
Pore
IEC
Figure 3 – Examples of surface irregularities
5.3 Chips and ragged edges
5.3.1 General
The minimum area is taken as 0,5 mm , to be distinguishable to the naked eye, and the
maximum allowable area is 25 mm .
Examples of allowable areas of chips are given in Annex C.
5.3.2 Chips and ragged edges on the mating surfaces
The areas of the chips located on the mating surfaces (chip 1 and chip 1' irregularities in
Figure 4) shall not exceed the following limits:
– the cumulative area of the chips shall be less than 6 % of the mating surface (whether
gapped or ungapped) of the centre pole;
– the total length of the ragged edges shall be less than 25 % of the perimeter of the
relevant surface.
5.3.3 Chips and ragged edges on the other surfaces
The allowable areas of chips on the other surfaces are doubled as compared to the limits for
the mating surface (see Figure 4).
The rule for ragged edges is the same as that for the mating surface.

– 10 – IEC 63093-11:2018 © IEC 2018
Matching surfaces
Chip 1'
Chip 2
Ragged
edge
Chip 1
IEC
Figure 4 – Chip location for EC-cores

Area and length reference for visual inspection is given in Table 4.
Table 4 – Area and length reference for visual inspection

– 12 – IEC 63093-11:2018 © IEC 2018
5.4 Cracks
The limits for cracks at various locations shown in Figure 5 are given in Table 5.
5.5 Flash
There shall be no flash extending from the core into the wire slot (see Figure 5).
5.6 Pull-outs
For EC-cores, the cumulative area of pull-outs of the core shall be less than 25 % of the total
respective surface area (see Figure 5).
H
S1''
S1
S1'
S3''
S3
S2
S7
S2'
S2''
S5
T
S5'
Flash
S5''
Pull-out
S4'
S3'
S4'''
S4''
S4
W
S6
S6'
IEC
Figure 5 – Crack and pull-out locations for EC-cores

Table 5 – Limits for cracks
Type Location Limits for Limits for
single crack multiple cracks
Mating surface of centre
S1 and S1' < 25 % of dimension W < 50 % of dimension W
pole
S1" Corner of centre pole Not acceptable Not acceptable
S2 and S2' Mating surface of outer leg < 25 % of dimension H < 25 % of dimension H
S2" Side of outer leg < 25 % of dimension H < 25 % of dimension H
S3 and S3" Centre pole < 25 % of dimension W < 25 % of dimension W
S3' Bottom corner of centre < 25 % of dimension W < 25 % of dimension W
pole / back wall and outer
leg / back wall
S4 Bottom corner of outer leg < 25 % of dimension T < 25 % of dimension T
/ back wall
S4' and S4" Back wall < 25 % of dimension T < 25 % of dimension T
S4''' Back wall < 50 % of dimension W < 100 % of dimension W
S5 and S5' and S5" Outer leg < 50 % of dimension W < 100 % of dimension W
S6 Back surface < 50 % of dimension W < 100 % of dimension W
S6' Back surface < 25 % of dimension W < 25 % of dimension W
S7 Corner of outer leg Not acceptable Not acceptable

5.7 Crystallites
Figure 6 shows an example of crystallite location on EC-cores:
– a single area of crystallites located on any surface shall be less than 2 % of the respective
surface area;
– the cumulative area of the crystallites located on any surface shall be less than 4 % of the
respective surface area (see Figure 6).
Crystallite
IEC
Figure 6 – Crystallite location for EC-cores
5.8 Pores
Figure 7 shows an example of pore location on EC-cores:
– the number of the pores located on the same surface shall not exceed two. The total
number of the pores located on all surfaces shall not exceed five;
– a hole with an area larger than 1 mm on any surface is not acceptable.

– 14 – IEC 63093-11:2018 © IEC 2018
Pore
IEC
Figure 7 – Pore location for EC-cores

Annex A
(normative)
Example of standard coil formers
Examples of standard coil formers for EC 35, EC 41, EC 52 and EC 70 cores are shown in
Fig
...