IEC 60205:2006
(Main)Calculation of the effective parameters of magnetic piece parts
Calculation of the effective parameters of magnetic piece parts
IEC 60205:2006 lays down uniform rules for the calculation of the effective parameters of closed circuits of ferromagnetic material.
Calcul des paramètres effectifs des pièces magnétiques
La CEI 60205:2006 établit des règles uniformes pour le calcul des paramètres effectifs des circuits fermés de matériaux ferromagnétiques.
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INTERNATIONAL IEC
STANDARD 60205
Third edition
2006-04
Calculation of the effective parameters
of magnetic piece parts
Reference number
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
The IEC is now publishing consolidated versions of its publications. For example,
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.
Further information on IEC publications
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology. Information relating to
this publication, including its validity, is available in the IEC Catalogue of
publications (see below) in addition to new editions, amendments and corrigenda.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is also available from the following:
• IEC Web Site (www.iec.ch)
• Catalogue of IEC publications
The on-line catalogue on the IEC web site (www.iec.ch/searchpub) enables you to
search by a variety of criteria including text searches, technical committees
and date of publication. On-line information is also available on recently issued
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INTERNATIONAL IEC
STANDARD 60205
Third edition
2006-04
Calculation of the effective parameters
of magnetic piece parts
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 U
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
– 2 – 60205 IEC:2006(E)
CONTENTS
FOREWORD.3
Scope.5
2 Basic rules.5
3 Formulae for the various types of cores.6
3.1 Ring cores .6
3.2 Pair of U-cores of rectangular section .7
3.3 Pair of U-cores of rounded section.7
3.4 Pair of E-cores of rectangular section .9
3.5 Pair of ETD/EER-cores .10
3.6 Pair of pot-cores .11
3.7 Pair of RM-cores .13
3.8 Pair of EP-cores .16
3.9 Pair of PM-cores.17
3.10 Pair of EL-cores.19
3.11 Pair of ER-cores (low profile) .21
3.12 Pair of PQ-cores.23
3.13 Pair of EFD-cores .25
3.14 Pair of E planar-cores .26
Annex A (informative) Purpose of revision .29
60205 IEC:2006(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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 60205 has been prepared by IEC technical committee 51: Magnetic
components and ferrite materials.
This third edition cancels and replaces the second edition published in 2001, corrigendum 1
(2001). This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) unit of angles through the text are described by using “radian”;
b) new words are added in 2.1 “All angles are in radians”;
l ln d g / d ln d g / d
l
2 2 3 2 2 3
c) replacement, Clause 3.9, of the equation = by = ;
A Dπ()h − h A Dπ()h − h / 2
2 1 2 2 1 2
d) new cores “EL, ER, PQ, EFD and E planar” are added in this edition.
– 4 – 60205 IEC:2006(E)
The text of this standard is based on the following documents:
FDIS Report on voting
51/848/FDIS 51/857/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication 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.
60205 IEC:2006(E) – 5 –
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
1 Scope
This International Standard lays down uniform rules for the calculation of the effective
parameters of closed circuits of ferromagnetic material.
2 Basic rules
The following basic rules are applicable to this standard.
2.1 All results shall be expressed in units based on the millimetre, shall be accurate to three
significant figures, but to derive l , A , and V the values of C and C shall be calculated to
e e e 1 2
five significant figures. All angles are in radians.
NOTE The purpose of specifying this degree of accuracy is only to ensure that parameters calculated at different
establishments are identical and it is not intended to imply that the parameters are capable of being determined to
this accuracy.
2.2 A is the nominal value of the smallest cross-section. All the dimensions used to
min
calculate A shall be the mean values between the tolerance limits quoted on the appropriate
min
piece part drawing.
2.3 Calculations are only applicable to the component parts of a closed magnetic circuit.
2.4 All dimensions used for the purpose of calculations shall be the mean value within the
tolerance limits quoted on the appropriate piece part drawing.
2.5 All irregularities in the outline of the core, such as small cut-outs, notches, chamfers, etc.
shall be ignored unless otherwise described.
2.6 When the calculation involves the sharp corner of a piece part, then the mean length of
flux path for that corner shall be taken as the mean circular path joining the centres of area of
the two adjacent uniform sections, and the cross-sectional area associated with that length
shall be taken as the average area of the two adjacent uniform sections.
Calculation of effective parameters l , A and V .
e e e
The effective parameters can be defined as
2 3 2
l = C /C A = C / C V = l A = C / C
e 1 2 e 1 2 e e e 1 2
where
l is the effective magnetic length of the core (mm);
e
A is the effective cross-sectional area (mm );
e
V is the effective volume (mm );
e
–1
C is the core constant (mm );
–3
C is the core constant (mm ).
– 6 – 60205 IEC:2006(E)
3 Formulae for the various types of cores
3.1 Ring cores
X
α
β
r
r
4×
4×
r
ϕ
h h h
X
Section X-X
IEC 584/06
2π
C =
h ln()d / d
e 1 2
4π()1/ d −1/ d
2 1
C =
2 3
h ln()d / d
e 1 2
3.1.1 For ring cores of rectangular cross-section with sharp corners
h = h
e
3.1.2 For ring cores of rectangular cross-section with an appreciable average rounding
radius r
1,7168r
h = h()1− k k =
e 1 1
h()d − d
1 2
3.1.3 For ring cores of trapezoidal cross-section with sharp corners
h()tanα + tan β
h = h()1− k k =
e 2 2
d − d
1 2
3.1.4 For ring cores of trapezoidal cross-section with an appreciable average
rounding radius r
h =()1− k − k
e 1 2
3.1.5 For ring cores of cross-section with circular arc frontal sides
d − d ϕ sinϕ ϕ
1 2
h = h − 2sin − −
e 2
4sin()ϕ / 2 2 2 2
d /2
d /2
d /2
d /2
60205 IEC:2006(E) – 7 –
d − d
1 2
ϕ = 2arcsin .
4r
NOTE When the winding is uniformly distributed over a ring core, it may be expected that, at all points inside the
ring core, the flux lines will be parallel to its surface.
No leakage flux will therefore leave or enter the ring core. This justifies the use of a theoretically more correct
derivation of the effective parameters which does not make use of the assumption that the flux is uniformly
distributed over the cross-section.
3.2 Pair of U-cores of rectangular section
NOTE U + PLT (Plate)-cores use U core formulas
q
l
l″ l′
4 4
X
A
Area
h
Y Y
A
Area
A
Area
l″ l′
5 5
X
Section Y-Y
l
Section X-X
IEC 585/06
Length of flux path associated with area A :
l = l′ + l′′
2 2 2
Mean length of flux paths at corners:
π
′ ′′
l = l + l =()p + h
4 4 4
π
′ ′′
l = l + l = ()s + h
5 5 5
Mean areas associated with l and l :
4 5
A + A
1 2
A =
A + A
2 3
A =
5 5
l l
i i
C = C =
1 ∑ 2 ∑ 2
A
A
= =
i 1 i i 1
i
3.3 Pair of U-cores of rounded section
NOTE U + PLT (Plate)-cores use U core formulas.
q
l″
l′
s p
– 8 – 60205 IEC:2006(E)
l
p
l″
...
IEC 60205 ®
Edition 3.0 2006-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Calculation of the effective parameters of magnetic piece parts
Calcul des paramètres effectifs des pièces magnétiques
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 your local IEC member National Committee for further information.
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
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et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
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IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: 0Hinmail@iec.ch
Web: 1Hwww.iec.ch
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.
ƒ Catalogue of IEC publications: 2Hwww.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
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in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
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IEC 60205 ®
Edition 3.0 2006-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Calculation of the effective parameters of magnetic piece parts
Calcul des paramètres effectifs des pièces magnétiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 29.100.10 ISBN 978-2-88910-071-2
– 2 – 60205 © IEC:2006
CONTENTS
FOREWORD.0H3
1 Scope.1H5
2 Basic rules.2H5
3 Formulae for the various types of cores.3H6
3.1 Ring cores .4H6
3.2 Pair of U-cores of rectangular section .5H7
3.3 Pair of U-cores of rounded section.6H7
3.4 Pair of E-cores of rectangular section .7H9
3.5 Pair of ETD/EER-cores .8H10
3.6 Pair of pot-cores .9H11
3.7 Pair of RM-cores .10H13
3.8 Pair of EP-cores .11H16
3.9 Pair of PM-cores.12H17
3.10 Pair of EL-cores.13H19
3.11 Pair of ER-cores (low profile) .14H21
3.12 Pair of PQ-cores.15H23
3.13 Pair of EFD-cores .16H25
3.14 Pair of E planar-cores .17H26
Annex A (informative) Purpose of revision .18H29
60205 © IEC:2006 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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 60205 has been prepared by IEC technical committee 51: Magnetic
components and ferrite materials.
This third edition cancels and replaces the second edition published in 2001, corrigendum 1
(2001). This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) unit of angles through the text are described by using “radian”;
b) new words are added in 2.1 “All angles are in radians”;
l ln d g / d ln d g / d
l
2 2 3 2 2 3
c) replacement, Clause 3.9, of the equation = by = ;
A Dπ()h − h A Dπ()h − h / 2
2 1 2 2 1 2
d) new cores “EL, ER, PQ, EFD and E planar” are added in this edition.
– 4 – 60205 © IEC:2006
This bilingual version, published in 2009-01, corresponds to the English version.
The text of this standard is based on the following documents:
FDIS Report on voting
51/848/FDIS 51/857/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.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication 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.
60205 © IEC:2006 – 5 –
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
1 Scope
This International Standard lays down uniform rules for the calculation of the effective
parameters of closed circuits of ferromagnetic material.
2 Basic rules
The following basic rules are applicable to this standard.
2.1 All results shall be expressed in units based on the millimetre, shall be accurate to three
significant figures, but to derive l , A , and V the values of C and C shall be calculated to
e e e 1 2
five significant figures. All angles are in radians.
NOTE The purpose of specifying this degree of accuracy is only to ensure that parameters calculated at different
establishments are identical and it is not intended to imply that the parameters are capable of being determined to
this accuracy.
2.2 A is the nominal value of the smallest cross-section. All the dimensions used to
min
calculate A shall be the mean values between the tolerance limits quoted on the appropriate
min
piece part drawing.
2.3 Calculations are only applicable to the component parts of a closed magnetic circuit.
2.4 All dimensions used for the purpose of calculations shall be the mean value within the
tolerance limits quoted on the appropriate piece part drawing.
2.5 All irregularities in the outline of the core, such as small cut-outs, notches, chamfers, etc.
shall be ignored unless otherwise described.
2.6 When the calculation involves the sharp corner of a piece part, then the mean length of
flux path for that corner shall be taken as the mean circular path joining the centres of area of
the two adjacent uniform sections, and the cross-sectional area associated with that length
shall be taken as the average area of the two adjacent uniform sections.
Calculation of effective parameters l , A and V .
e e e
The effective parameters can be defined as
2 3 2
l = C /C A = C / C V = l A = C / C
e 1 2 e 1 2 e e e 1 2
where
l is the effective magnetic length of the core (mm);
e
A is the effective cross-sectional area (mm );
e
V is the effective volume (mm );
e
–1
C is the core constant (mm );
–3
C is the core constant
...
IEC 60205 ®
Edition 3.1 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Calculation of the effective parameters of magnetic piece parts
Calcul des paramètres effectifs des pièces magnétiques
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 your local IEC member National Committee for further information.
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.
IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
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.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.
A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
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IEC 60205 ®
Edition 3.1 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Calculation of the effective parameters of magnetic piece parts
Calcul des paramètres effectifs des pièces magnétiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CL
CODE PRIX
ICS 29.100.10 ISBN 978-2-88910-073-6
– 2 – 60205 © IEC:2006+A1:2009
CONTENTS
FOREWORD.3
1 Scope.5
2 Basic rules.5
3 Formulae for the various types of cores.6
3.1 Ring cores .6
3.2 Pair of U-cores of rectangular section .7
3.3 Pair of U-cores of rounded section.7
3.4 Pair of E-cores of rectangular section .9
3.5 Pair of ETD/EER-cores .10
3.6 Pair of pot-cores .11
3.7 Pair of RM-cores .13
3.8 Pair of EP-cores .16
3.9 Pair of PM-cores.17
3.10 Pair of EL-cores.19
3.11 Pair of ER-cores (low profile) .21
3.12 Pair of PQ-cores.23
3.13 Pair of EFD-cores .26
3.14 Pair of E planar-cores .27
Annex A (informative) Purpose of revision .30
60205 © IEC:2006+A1:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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 60205 has been prepared by IEC technical committee 51: Magnetic
components and ferrite materials.
This consolidated version of IEC 60205 consists of the third edition (2006) [documents
51/848/FDIS and 51/857/RVD] and its amendment 1 (2009) [documents 51/928A/CDV and
51/940/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 3.1.
A vertical line in the margin shows where the base publication has been modified by
amendment 1.
The French version of this standard has not been voted upon.
– 4 – 60205 © IEC:2006+A1:2009
This edition includes the following significant technical changes with respect to the previous
edition:
a) unit of angles through the text are described by using “radian”;
b) new words are added in 2.1 “All angles are in radians”;
l ln d g / d ln d g / d
l
2 2 3 2 2 3
c) replacement, Clause 3.9, of the equation = by = ;
A Dπ()h − h A Dπ()h − h / 2
2 1 2 2 1 2
d) new cores “EL, ER, PQ, EFD and E planar” are added in this edition.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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.
60205 © IEC:2006+A1:2009 – 5 –
CALCULATION OF THE EFFECTIVE PARAMETERS
OF MAGNETIC PIECE PARTS
1 Scope
This International Standard lays down uniform rules for the calculation of the effective
parameters of closed circuits of ferromagnetic material.
2 Basic rules
The following basic rules are applicable to this standard.
2.1 All results shall be expressed in units based on the millimetre, shall be accurate to three
significant figures, but to derive l , A , and V the values of C and C shall be calculated to
e e e 1 2
five significant figures. All angles are in radians.
NOTE The purpose of specifying this degree of accuracy is only to ensure that parameters calculated at different
establishments are identical and it is not intended to imply that the parameters are capable of being determined to
this accuracy.
2.2 A is the nominal value of the smallest cross-section. All the dimensions used to
min
calculate A shall be the mean values between the tolerance limits quoted on the appropriate
min
piece part drawing.
2.3 Calculations are only applicable to the component parts of a closed magnetic circuit.
2.4 All dimensions used for the purpose of calculations shall be the mean value within the
tolerance limits quoted on the appropriate piece part drawing.
2.5 All irregularities in the outline of the core, such as small cut-outs, notches, chamfers, etc.
shall be ignored unless otherwise described.
2.6 When the calculation involves the sharp corner of a piece part, then the mean length of
flux path for that corner shall be taken as the mean circular path joining the centres of area of
the two adjacent uniform sections, and the cross-sectional area associated with that length
shall be taken as the average area of the two adjacent uniform sections.
Calculation of effective parameters l , A and V .
e e e
The effective parameters can be defined as
2 3 2
l = C /C A = C / C V = l A = C / C
e 1 2 e 1 2 e e e 1 2
where
l is the effective magnetic length of the core (mm);
e
A is the effective cross-sectional area (mm );
e
V is the effective volume (mm );
e
–1
C is the core constant (mm );
–3
C is the core constant (mm ).
...
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