IEC 63093-10:2026

IEC 63093-10 ®
Edition 2.0 2026-02
INTERNATIONAL
STANDARD
REDLINE VERSION
Ferrite cores - Guidelines on dimensions and the limits of surface irregularities -
Part 10: PM-cores and associated parts
ICS 29.100.10 ISBN 978-2-8327-1067-8
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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 PM-cores . 5
4.2.1 Principal dimensions . 5
4.2.2 Effective parameter and A values . 7
min
4.3 Main dimensions of coil formers . 7
4.4 Pin locations and base outlines . 8
4.5 Pin diameter . 8
5 Mounting hardware . 8
6 Limits of surface irregularities . 9
6.1 General . 9
6.2 Examples of surface irregularities . 9
6.3 Chips and ragged edges . 10
6.3.1 General . 10
6.3.2 Chips and ragged edges located on the mating surface . 10
6.3.3 Chips and ragged edges located on other surfaces . 11
6.4 Cracks . 11
6.5 Pull-out . 12
6.6 Crystallites . 13
6.7 Flash . 13
6.8 Pores . 14
Annex A (normativeinformative) Derived standards . 15
Annex B (normativeinformative) Example of a gauge to check the coil former space
dimensions of PM‑cores meeting the IEC primary standard . 16
Annex C (informative) Recommended main dimensions for mounting hardware . 17
Annex D (informative) Limits of allowable chipping areas . 19

Figure 1 – Main dimensions of PM-cores . 6
Figure 2 – Main dimensions of coil formers . 7
Figure 3 – Pin locations and base outlines viewed from the underside of the board . 9
Figure 4 – Examples of surface irregularities . 10
Figure 5 – Chips on mating surfaces . 11
Figure 6 – Locations of cracks . 12
Figure 7 – Location of pull-out . 13
Figure 8 – Location of a crystallite . 13
Figure 9 – Location of a flash . 14
Figure 10 – Location of pore . 14
Figure B.1 – Example of a gauge . 16
Figure C.1 – Main dimensions of mounting hardware . 17

Table 1 – Main dimensions of PM-cores . 6
Table 2 – Effective parameter and A values . 7
min
Table 3 – Main dimensions of coil formers . 8
Table 4 – Limits for cracks . 12
Table B.1 – Example of a gauge . 16
Table C.1 – Main dimensions of U-bolt . 17
Table C.2 – Main dimensions of base plate . 18
Table D.1 – Limits of allowable chipping areas. 19

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Ferrite cores -
Guidelines on dimensions and the limits of surface irregularities -
Part 10: PM-cores and associated parts

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 63093-10:2022. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 63093-10 has been prepared by IEC technical committee 51: Magnetic components, ferrite
and magnetic powder materials. It is an International Standard.
This second edition cancels and replaces the first edition published in 2022. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) revision of Table 2 according to IEC 60205 ED4.
The text of this International Standard is based on the following documents:
Draft Report on voting
51/1585/FDIS 51/1598/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
1 Scope
This part of IEC 63093 specifies the dimensions that are of importance for mechanical
interchangeability for a preferred range of PM-cores made of magnetic oxides, the main
dimensions for coil formers to be used with these cores and the locations of their pins on a
modular printed wiring grid in relation to the base outlines of cores. It also specifies the effective
parameter values to be used in calculations and gives guidelines on allowable limits of surface
irregularities applicable to the PM-cores.
The use of derived standards which give more detailed specifications of component parts whilst
still permitting compliance with this document is discussed in Annex A.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 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 and reference of dimensions
IEC 63093-1:2020, Ferrite cores - Guidelines on dimensions and 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 63093-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
4 Primary dimensions
4.1 General
Compliance with the following requirements ensures mechanical interchangeability of complete
assemblies and wound coil formers.
4.2 Dimensions of PM-cores
4.2.1 Principal dimensions
The principal dimensions of PM-cores shall be as given in Figure 1 and Table 1.
Figure 1 – Main dimensions of PM-cores
Table 1 – Main dimensions of PM-cores
Size
Dimension
PM 50/39 PM 62/49 PM 74/59 PM 87/70 PM 114/93
K Max. 50,0 62,0 74,0 87,0 114,0
mm Min. 48,3 60,0 71,5 84,0 109,5
E Max. 40,3 50,3 59,3 69,2 91,7
mm Min. 39,0 48,8 57,5 67,1 88,0
F Max. 20,0 25,5 29,5 31,7 43,0
mm Min. 19,4 24,7 28,5 30,7 41,6
H Max. 5,7 5,7 5,7 8,8 5,8
mm Min. 5,4 5,4 5,4 8,5 5,4
2B Max. 39,0 49,0 59,0 70,0 93,0
mm Min. 38,6 48,6 58,4 69,2 92,0
2D Max. 27,2 34,2 41,5 48,8 64,6
mm Min. 26,4 33,4 40,7 48,0 63,0
C Max. 23,0 28,5 33,0 36,0 45,0
mm Min. 22,0 27,5 32,0 35,0 44,0
α Max. 125 125 125 95 95
degree Min. 115 115 115 85 85
J Max. 7,8 10,5 13,5 8,3 11,5
mm Min. 6,8 9,5 12,5 7,3 10,5
G Max. 23,4 29,0 34,0 40,0 52,0
mm Min. 22,4 28,0 33,0 39,0 51,0
t Max. 1,6 1,6 2,9 3,9 4,4
mm Min. 1,2 1,2 2,5 3,5 4,0
I Max. 5,0 5,0 5,0 5,5 6,3
mm Min. 4,0 4,0 4,0 4,5 5,3
The dimensions of the cores can be checked by means of gauges. By way of example, a possible standard for
these gauges is given in Annex B. In order to facilitate production it can be necessary to use gauges having
dimensions differing from those given in Annex B, although no relaxation of the requirements for the dimensions
of the cores given in 4.2.1 is thereby permitted.

4.2.2 Effective parameter and A values
min
The effective parameter and A values for PM-cores whose dimensions comply with 4.2.1
min
shall be as given in Table 2. The definitions of effective parameters and their calculations shall
be as given in IEC 60205.
Table 2 – Effective parameter and A values
min
a
C C l A V
A
Size
1 2 e e e
min
−1 −3 −3 2 3 2
mm
mm ×10 mm mm mm mm
PM 50/39 0,280 49 0,856 46 91,9 327 30 100
0,271 19 0,809 05 90,9 335 30 500
PM 62/49 0,219 52 0,415 09 116 529 61 000 470
0,212 97 0,393 69 115 541 62 300 471
PM 74/59 0,186 88 0,250 48 139 746 104 000 630
0,183 84 0,245 34 138 749 103 000 636
PM 87/70 0,186 10 0,217 24 159 857 137 000 700
0,179 71 0,204 63 158 878 139 000 706
PM 114/93 0,132 85 0,082 050 215 1 620 348 000
1 380
0,129 15 0,078 258 213 1 650 352 000
a
A is located at the centre pole only.
min
4.3 Main dimensions of coil formers
The main dimensions of coil formers shall be as given in Figure 2 and Table 3.

Figure 2 – Main dimensions of coil formers
Table 3 – Main dimensions of coil formers
Size
Dimension
PM 50/39 PM 62/49 PM 74/59 PM 87/70 PM 114/93
e
Max. 38,6 48,5 57,2 66,4 87,3
mm Min. 38,2 48,1 56,7 65,8 86,0
e
Max. 23,4 28,7 32,7 35,2 48,2
mm Min. 23,0 28,3 32,3 34,7 47,0
f Max. 20,4 26,1 30,3 32,7 44,6
mm Min. 20,2 25,8 29,9 32,1 43,8
2d Max. 26,0 33,0 40,0 47,3 62,5
mm Min. 25,6 32,5 39,3 46,5 61,3
s
Max. 1,25 1,35 1,35 1,55 2,30
mm Min. 0,95 1,05 1,05 1,25 2,00
s
Max. 1,65 1,65 1,75 1,95 2,50
mm Min. 1,35 1,35 1,45 1,65 2,20

4.4 Pin locations and base outlines
When coil formers are provided with pins intended for use in conjunction with a printed wiring
board, they shall be inserted in the thicker flange (s ), and their location, numbering and
relationship to the core base outline shall be as shown in Figure 3, in which the bases are
viewed from the pin side, that is, from the underside of the printed wiring board. The module,
designated m, shown in the grid plan should be 2,50 mm.
NOTE The largest core PM 114/93 is not intended to be mounted on terminal pins because of its weight. In this
case pins are usually fitted within the cut out of the core.
4.5 Pin diameter
Coil former terminations (pins) shall be accepted by a gauge having 1,2 mm holes on specified
positions.
5 Mounting hardware
No mounting hardware is specified here, however an example is as given in Annex C.
NOTE Components using PM-cores with fully wound coil formers will normally require
mechanical support in addition to their printed wiring board mounting. In Annex C, details are
given of an assembly consisting of a 3 mm diameter circular section U-bolt with threaded ends
which can be used in conjunction with a 0,6 mm thick base plate. Both components are made
from non-magnetic materials. The largest core PM 114/93 has a mass approaching 2 kg before
winding. lt is not possible, therefore, to recommend any simple mounting method and users are
expected to design specific mounting hardware according to their application.
Key
m module in the grid plan
NOTE 1 The earth point is the holes for U-bolt fixing.
NOTE 2 The location of pin no.1 is identified by a corresponding mark on the upper flange s in Figure 2.
Figure 3 – Pin locations and base outlines viewed from the underside of the board
6 Limits of surface irregularities
6.1 General
Surface irregularities are defined in IEC 63093-1.
6.2 Examples of surface irregularities
Figure 4 shows different examples of surface irregularities on a PM-core.
Figure 4 – Examples of surface irregularities
6.3 Chips and ragged edges
6.3.1 General
The minimum chipping area is taken to be 0,5 mm , so as to be distinguishable to the naked
eye.
The maximum chipping area is taken to be 50 mm in order not to reduce the commercial value
because of its appearance.
6.3.2 Chips and ragged edges located on the mating surface
The areas of the chips located on the mating surface (see C1, C1', C1'', R1 and R1' irregularities
in Figure 5) shall not exceed the following limits:
– the cumulative area of the chips located on the mating surface shall be less than 4 % of the
total mating surface;
– the cumulative area of the chips located on the centre pole mating surface shall be less than
2 % of the total mating surface;
– the cumulative area of the chips located on the mating surface of one outer leg shall be less
than 1 % of the total mating surface.
The total length of the ragged edges shall be less than 25 % of the perimeter of the relevant
mating surface.
Key
C1, C1′, C1″, C2 chips
R1, R1′ ragged edges
Figure 5 – Chips on mating surfaces
Examples of allowable chipping areas for a given core are summarized in Annex D.
6.3.3 Chips and ragged edges located on other surfaces
For chips and ragged edges located on other surfaces:
– the allowable chipping areas are doubled as compared to the limits for the whole mating
surfaces;
– the rule for the ragged edges is the same as for the mating surfaces;
– chips and ragged edges are not acceptable on the inner edges of the wire slot area.
The area and length reference of irregularities for visual inspection are given IEC 63093-1:2020.
6.4 Cracks
Figure 6 shows examples of cracks locations on PM-cores:
– a single crack which intersects the perimeter of the relevant surface at two points is not
acceptable (see S1 in Figure 6);
– the number of cracks located on the same surface shall not exceed three;
– the limits of cracks at various locations shown in Figure 6 are given in Table 4.
Key
NOTE S1 to S9 types of cracks (for limits for cracks, see Table 4)
Figure 6 – Locations of cracks
Table 4 – Limits for cracks
a
Location Limits for single crack Limits for multiple cracks
Type
S1 Any place Not acceptable Not acceptable
S2 Outer wall 20 % × W 40 % × W
S3 Mating surface of outer legs 20 % × W 40 % × W
S4 Mating surface of centre pole 20% × F 40 % × F
S5 Bottom surface 25 % × T 50 % × T
S6 Back wall 25 % × T 50 % × T
S7 Centre-pole wall 20% × F 40 % × F
S8 Back surface 25 % × W 50 % × W
S9 Back surface 20 % × W 40 % × W
For F, T, W, see Figure 6.
a
See Figure 6.
6.5 Pull-out
Figure 7 shows an example of a pull-out location on the PM-core.
The cumulative area of the pull-outs on the bottom surface of the core shall be less than 25 %
of the total respective surface area.
Figure 7 – Location of pull-out
6.6 Crystallites
Figure 8 shows an example of a crystallite location on the PM-core:
– the single area of the 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.
Figure 8 – Location of a crystallite
6.7 Flash
Figure 9 shows an example of a flash location on the PM-core:
– there shall be no flash extending from the core into the wire slot;
– with chamfering around the back surface, the flash height shall not exceed the back surface
of the core;
– without chamfering around the back surface, flash is not acceptable.
Figure 9 – Location of a flash
6.8 Pores
Figure 10 shows an example of pore location on the PM-core:
– the number of pores located on the same surface shall not exceed 2; the total number of
pores located on all surfaces shall not exceed 5;
– a hole with an area larger than 1 mm on any surface is not acceptable.

Figure 10 – Location of pore
Annex A
(normativeinformative)
Derived standards
The primary standard given in the main text establishes values for the main dimensions of core
assemblies and coil formers and enables full interchangeability to be achieved for components
complying with this document.
Parties interested in producing or using PM-cores can find it desirable to lay down local
standards for everyday use, which show the dimensions and tolerances in greater detail than
Clause 4, and which correspond to the state of the art in that area. These are known as derived
standards. When doing so, any other type of PM-core meeting the IEC primary standard should
not be excluded, which would also satisfy the performance specification valid for a specific case.
lt should be noted that Whilst a component complying with a derived standard will comply with
the requirements of Clause 4 for the primary standard and therefore permit core assemblies
and coil formers to be freely interchanged, the parts thereof may are not necessarily be
interchangeable.
When requirements would lead to the establishing of a national standard, the relevant national
standardization body should insert a note in such a national standard that:
a) it is in accordance with the dimensional requirements of this document, but that more details
are given in order to promote its practical use;
b) other solutions are possible within the framework of this IEC standard, and should not be
excluded if the resulting cores and coil formers are functionally interchangeable with those
according to the national standard.
Annex B
(normativeinformative)
Example of a gauge to check the coil former space dimensions of
PM‑cores meeting the IEC primary standard
An example of the coil former space dimensions of PM-cores shown in Figure B.1 and Table B.1.

Figure B.1 – Example of a gauge
Table B.1 – Example of a gauge
Size
Dimension
PM 50/39 PM 62/49 PM 74/59 PM 87/70 PM 114/93
d
Min. 38,985 48,785 57,485 67,085 87,985
mm Max. 38,995 48,795 57,495 67,095 87,995
d
Min. 20,005 25,505 29,505 31,705 43,005
mm Max. 20,015 25,515 29,515 31,715 43,015
h
Min. 26,385 33,385 40,685 47,985 62,985
mm Max. 26,395 33,395 40,695 47,995 62,995
f Min. 0,41 0,90 0,90 1,875 2,875
mm Max. 0,59 1,10 1,10 2,125 3,125

Annex C
(informative)
Recommended main d
...