IEC TR 60297-3-1:2023

Mechanical structures for electrical and electronic equipment - Dimensions of mechanical structures of the 482,6 mm (19 in) series - Part 3-1: Technological schemes and applications

IEC 60297-3-1:2023 provides information on the technological schemes of the IEC 60297 series and shows how to apply the 19-inch series standards for the mechanical structure practices for electrical and electronic equipment.

General Information

• Status: Published
• Publication Date: 06-Feb-2023
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: SC 48D - Mechanical structures for electrical and electronic equipment
• Current Stage: PPUB - Publication issued
• Start Date: 21-Feb-2023
• Completion Date: 07-Feb-2023

Standards Content (Sample)

IEC TR 60297-3-1
®

Edition 1.0 2023-02
TECHNICAL
REPORT

colour
inside


Mechanical structures for electrical and electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series
Part 3-1: Technological schemes and applications
IEC TR 60297-3-1:2023-02(en)

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IEC TR 60297-3-1

®


Edition 1.0 2023-02




TECHNICAL



REPORT








colour

inside










Mechanical structures for electrical and electronic equipment – Dimensions of

mechanical structures of the 482,6 mm (19 in) series

Part 3-1: Technological schemes and applications

























INTERNATIONAL

ELECTROTECHNICAL


COMMISSION





ICS 31.240 ISBN 978-2-8322-6398-3




  Warning! Make sure that you obtained this publication from an authorized distributor.


® Registered trademark of the International Electrotechnical Commission

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– 2 – IEC TR 60297-3-1:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Technological scheme of the IEC 60297 series . 10
4.1 Development history and technological background . 10
4.1.1 General . 10
4.1.2 Development of the 482,6 mm (19 in) subracks and associated plug-in
units (19-inch subrack system) . 10
4.1.3 Adoption of IEC 60603-2 connector in the 482,6 mm (19 in) subracks
and associated plug-in units ("19-inch subrack system") . 13
4.1.4 Modular structure of the 482,6 mm (19 in) series . 14
4.2 Extended specifications of the 486,2 mm (19 in) series . 16
4.2.1 General . 16
4.2.2 Extended specifications of 19-inch subrack system by the IEC 60917
series . 16
4.2.3 Enhanced 19-inch subrack system from the market applications . 18
5 Definition domains of the 482,6 mm (19 in) series standards . 18
6 Prospect for further applications and standards development of the 19-inch
subrack system . 20
Annex A (informative) Applicable connectors to the 482,6 mm (19 in) subracks and
associated plug-in units . 21
A.1 General conditions of the applicable connectors . 21
A.2 List of applicable connectors . 22
Annex B (informative) IEEE and VITA standards related with the 482,6 mm (19 in)
series . 25
B.1 Subracks and associated plug-in units . 25
B.2 Mezzanine card standards . 25
B.3 Conduction cooling . 28
B.4 Environmental specifications . 31
Bibliography . 33

Figure 1 – Unified printed board size accommodated with height and depth of the
subracks (recommended dimension matrix) . 12
Figure 2 – Typical image of 19-inch subrack system (6U subrack with plug-in units,
where the plug-in units are interconnected by a backplane fixed on the subrack frame) . 13
Figure 3 – Modular structure of the 482,6 mm (19 in) series. 15
Figure 4 – Basic dimensions of the modular structure of the 482,6 mm (19 in) series . 16
Figure 5 – Definition domains of the 482,6 mm (19 in) series standards . 20
Figure A.1 – Dimensional relations of the connectors within mating condition, in the
482,6 mm (19 in) subracks and associated plug-in units . 22
Figure B.1 – Examples of mezzanine card size (coordination dimensions as 25 mm
grid) and mezzanine card boundary envelope in IEEE 1301.4 . 26
Figure B.2 – Example of adoption of CMC single size on 6U depth 160 mm plug-in unit,
and outline of single size CMC (common mezzanine card) in IEEE 1386. 26
Figure B.3 – Outline of the CCA of 6U VME module in IEEE 1101.2 . 29

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IEC TR 60297-3-1 © IEC 2023 – 3 –
Figure B.4 – Assembly of VPX-REDI 3U conduction cooled plug-in unit . 30
Figure B.5 – Assembly of VPX-REDI 3U conduction cooled chassis . 30

Table A.1 – Applicable connectors to the 482,6 mm (19 in) subracks and associated
plug-in units . 23
Table B.1 – IEEE and VITA standards for mezzanine cards applied on 19-inch subrack
system . 27
Table B.2 – Environmental class for the plug-in units in ANSI/VITA 47 . 31

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– 4 – IEC TR 60297-3-1:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MECHANICAL STRUCTURES FOR ELECTRICAL AND
ELECTRONIC EQUIPMENT – DIMENSIONS OF MECHANICAL
STRUCTURES OF THE 482,6 mm (19 in) SERIES

Part 3-1: Technological schemes and 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,
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consensus of opinion on the relevant subjects since each technical committee has representation from all
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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.
IEC TR 60297-3-1 has been prepared by subcommittee 48D: Mechanical structures for
electrical and electronic equipment, of IEC technical committee 48: Electrical connectors and
mechanical structures for electrical and electronic equipment. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
48D/756/DTR 48D/757/RVDTR

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 Technical Report is English.

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IEC TR 60297-3-1 © IEC 2023 – 5 –
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 60297 series, published under the general title Mechanical structures
for electrical and electronic equipment – Dimensions of mechanical structures of the 482,6 mm
(19 in) series, can be found on the IEC website.
Future documents in this series will carry the new general title as cited above. Titles of existing
documents in this series will be updated at the time of the next edition.
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,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

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– 6 – IEC TR 60297-3-1:2023 © IEC 2023
INTRODUCTION
The IEC 60297 series contains dimensional definitions of the entire mechanical structure layers
from level 1 to level 4 for electrical and electronic equipment practices. Nowadays, the
IEC 60917-1 generic standard defines all the elements and components in the mechanical
structure layers from level 1 to level 4, and they are adopted for the IEC 60917-2 (metric) series.
The original concept of the mechanical structure layers was established in DIN 41494 and
introduced into the former IEC 297 series, later republished as the IEC 60297 series. Therefore,
the second edition of IEC 60917-1:2019 (generic) categorizes the existing IEC 60297 series as
a "conventional standard (legacy system)", which contains the detail dimensions of the structure
levels from level 1 to level 4 as well as the structure levels of the IEC 60917-2 series (metric).
Applications of the IEC 60297 series are divided into two different perceptions by the users:
a) the traditional 19-inch racks and chassis configurations, and
b) the 19-inch subrack system.
The latter has been providing effective and rational solutions for the critical issues on
interconnection and packaging for electronic equipment, which have been in a close relationship
with the IEC connector standards of IEC SC 48B, in the microelectronics era since the 1960s.
In the 1980s, the 19-inch subrack system was adopted as the mechanical specifications for
open computer bus standards in the IEEE and other manufacturers' associations or industrial
consortia. In such fields, not only newly developed high-performance connectors have been
applied, but also advanced mechanical features have been developed, based on the 19-inch
subrack system. These new technologies have been standardized, and their efforts considered
as development for extended specifications for the 19-inch subrack system in IEC SC 48D.
From these points of view, this Technical Report has been prepared to provide the following
information, not only for users of the IEC 60297 series standards, but also for the engineers
who will develop new architectures or hardware for advanced ICT equipment or systems for the
current IoT or Industry 4.0 era:
– information on technological schemes of the IEC 60297 series standards, which have been
in development for over 40 years in IEC TC 48/SC 48D. (In the market for industrial
electronics and information and communication technology (ICT), there are active users who
take the two different approaches regarding the application or adoption of the technologies
from the IEC 60297 series standards);
– the technological background of the standards, and the principles or concepts, which had
been adopted to cope with the technological evolutions through the development process of
the IEC 60297 series standards in IEC SC 48D;
– in standardization for mechanical structures for electrical and electronic equipment in
IEC SC 48D, IEC 60917-1 has been published as the generic standard for modular order for
the development of mechanical structures for electrical and electronic equipment practices.
The IEC 60297 series also considered that the dimensions of the mechanical structure are
partly in accordance with IEC 60917-1. This document clarifies the relationship between the
IEC 60917 series and the IEC 60297 series;
– to introduce the domain of each part of the IEC 60297 series for structures for electrical and
electronic equipment.
Annex A introduces applicable connectors for the 19-inch subrack system, including newly
developed high-performance connectors which are not (yet) published as IEC SC 48B
standards.

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IEC TR 60297-3-1 © IEC 2023 – 7 –
Annex B introduces relationships and compatibilities between the 19-inch subrack system
standards in IEC SC 48D, the IEEE standards for the 19-inch subrack and plug-in units, and
other industrial standards for the mechanical specifications. It also shows outlines of the
extended mechanical features adopted for the 19-inch subrack system. These features include
the implementations of the mezzanine cards and the conduction cooled system, and they are
not yet defined in IEC SC 48D standards.
Through the study of the additional information given in Annex A and Annex B, further prospects
on applications of the 19-inch subrack system will be seen, and the directions of the next
standards development in IEC TC 48/SC 48D will be provided.

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– 8 – IEC TR 60297-3-1:2023 © IEC 2023
MECHANICAL STRUCTURES FOR ELECTRICAL AND
ELECTRONIC EQUIPMENT – DIMENSIONS OF MECHANICAL
STRUCTURES OF THE 482,6 mm (19 in) SERIES

Part 3-1: Technological schemes and applications



1 Scope
This part of IEC 60297 provides information on the technological schemes of the IEC 60297
series, and shows how to apply the 19-inch series standards for the mechanical structure
practices for electrical and electronic equipment.
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 60297-3-100:2008, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-100: Basic dimensions of front
panels, subracks, chassis, racks and cabinets
IEC 60297-3-101:2004, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-101: Subracks and associated
plug-in units
IEC 60297-3-102:2004, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-102: Injector/extractor handle
IEC 60297-3-103:2004, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-103: Keying and alignment pin
IEC 60297-3-104:2006, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-104: Connector dependent
interface dimensions of subracks and plug-in units
IEC 60297-3-105:2008, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-105: Dimensions and design
aspects for 1U high chassis
IEC 60297-3-106:2010, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-106: Adaptation dimensions for
subracks and chassis applicable with metric cabinets or racks in accordance with
IEC 60917-2-1
IEC 60297-3-107:2012, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-107: Dimensions of subracks and
plug-in units, small form factor
IEC 60297-3-108:2014, Mechanical structures for electronic equipment – Dimensions of
mechanical structures of the 482,6 mm (19 in) series – Part 3-108: Dimensions of R-type
subracks and plug-in units

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IEC TR 60297-3-1 © IEC 2023 – 9 –
IEC 60297-3-109:2015, Mechanical structures for electrical and electronic equipment –
Dimensions of mechanical structures of the 482,6 mm (19 in) series – Part 3-109: Dimensions
of chassis for embedded computing devices
IEC 60297-3-110:2018, Mechanical structures for electrical and electronic equipment –
Dimensions of mechanical structures of the 482,6 mm (19 in) series – Part 3-110: Residential
racks and cabinets for smart houses
IEC 60603-2, Connectors for frequencies below 3 MHz for use with printed boards – Part 2:
Detail specification for two-part connectors with assessed quality, for printed boards, for basic
grid of 2,54 mm (0,1 in) with common mounting features
IEC 60917-1, Modular order for the development of mechanical structures for electrical and
electronic equipment practices – Part 1: Generic standard
IEC 60917-2:1992, Modular order for the development of mechanical structures for electronic
equipment practices – Part 2: Sectional specification – Interface co-ordination dimensions for
the 25 mm equipment practice
IEC 60917-2-1:1993, Modular order for the development of mechanical structures for electronic
equipment practices – Part 2: Sectional specification – Interface co-ordination dimensions for
the 25 mm equipment practice – Section 1: Detail specification – Dimensions for cabinets and
racks
IEC 60917-2-2:1994, Modular order for the development of mechanical structures for electronic
equipment practices – Part 2: Sectional specification – Interface co-ordination dimensions for
the 25 mm equipment practice – Section 2: Detail specification – Dimensions for subracks,
chassis, backplanes, front panels and plug-in units
IEC 61076-4-100, Connectors for electronic equipment – Part 4-100: Printed board connectors
with assessed quality – Detail specification for two-part connector modules having a grid of
2,5 mm for printed boards and backplanes
IEC 61076-4-101, Connectors for electronic equipment – Part 4-101: Printed board connectors
with assessed quality – Detail specification for two-part connector modules, having a basic grid
of 2,0 mm for printed boards and backplanes in accordance with IEC 60917
IEC 61076-4-113, Connectors for electronic equipment – Printed board connectors – Part 4-113:
Detail specification for two-part connectors having 5 rows with a grid of 2,54 mm for printed
boards and backplanes in bus applications
IEC 61076-4-116, Connectors for electronic equipment – Product requirements – Part 4-116:
Printed board connectors – Detail specification for a high-speed two-part connector with
integrated shielding function
3 Terms and definitions
No terms and definitions are listed in this document.
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

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– 10 – IEC TR 60297-3-1:2023 © IEC 2023
4 Technological scheme of the IEC 60297 series
4.1 Development history and technological background
4.1.1 General
This Subclause 4.1 introduces the history of the development and the applications of the
IEC 60297-X series in IEC SC 48D.
1
The initial standards of the IEC 60297-X series were published at the beginning of the 1980s.
Before the publication of IEC standards, there was the EIA 19-inch rack standard (ANSI/EIA
2
RS310-C 1971 Rack, Panels and Associated Equipment ), and the combination of 19-inch racks
or cabinets and 19-inch chassis (modular chassis) in accordance with the EIA standard had
been used broadly for telecommunication, instrumentation, and other electronic equipment in
many countries. This model is still being applied to current IT equipment, servers, etc., which
are mounted within the 19-inch racks/cabinets in datacentres. It is the traditional 19-inch rack
and chassis configuration of the 482,6 mm (19 in) standard series.
3
IEC 60297-3 was published in 1984. This standard was developed by DIN and IEC SC 48D
under the following circumstances.
4.1.2 Development of the 482,6 mm (19 in) subracks and associated plug-in units
(19-inch subrack system)
In the middle of the 1960s, to cope with the expanding adoption of printed boards (PBs) in the
fields of industrial electronics and telecommunication equipment, the development of a
mechanical structure for housing PBs in a rack started in Germany. The dimensions of the rack
and chassis were adopted from the 19-inch EIA standard, and the following development
concept was established to mount the PBs into the 19-inch modular chassis as the structure of
482,6 mm (19 in) subracks and associated plug-in units.
Electronic equipment for telecommunication or industrial uses is required to obtain reliability,
compatibility and interchangeability for easy maintenance. In such electronic equipment, in the
case where one electronic system consists of multiple PCBs (functional units/sub-systems, they
are interconnected in one chassis), its hardware should adopt the mechanical structure
described above. And, the mechanical structure, 482,6 mm (19 in) subracks and associated
plug-in units, shall be designed based on the following principles.
• The sizes of PBs of plug-in units are unified and based on the height and depth of the
accommodated subracks.
• The adopted connectors on the PBs of plug-in units are unified and standardized to establish
4
the interconnection between plug-in units (via a backplane or wire-wrap , which is a cable-
connecting technology between tail pins of fixed connectors on the backside of a subrack).
• The plug-in units are placed vertically in the subracks to promote convective air flow for heat
dissipation.
___________
1
 The main parts of the IEC 60297-X series were published in the 1980s. IEC 60297-1:1986 and IEC 60297-2:1982
were merged into IEC 60297-3-100:2008.
2
 The standard defines a flange width of 19 in (482,6 mm) and a height pitch of 1U = 1,75 in (44,45 mm) for
mounting the chassis to the rack.
3
IEC 60297-3:1984 was replaced by IEC 60297-3-101:2004.
4
 Wrapped connections are described in IEC 60352-1.

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IEC TR 60297-3-1 © IEC 2023 – 11 –
In accordance with these principles, the basic size of the PB for the 482,6 mm (19 in) subracks
5
was defined as 100 mm × 100 mm and adopted for the 3U high subrack . One connector in
accordance with IEC 60603-2/DIN 41612 is placed on the 100 mm high PB. The extended sizes
were also defined with regard to height as the double-size with two connectors for a 6U subrack
and triple-size with three connectors placed on a 9U subrack, and with regard to depth in
increments of 60 mm (see Figure 1 and Figure 2).
These modular structures and dimensions were adopted by DIN standards and proposed in
IEC SC 48D. Consequently IEC 60297-3 was published in 1984.
The mechanical architecture of the 19-inch subrack system consists of plug-in units (connectors
and PBs assembled with other mechanical parts) and subracks, in which the plug-in units are
interconnected via the adoption of standard connectors on a backplane in a subrack. The
configuration of the 19-inch subrack system has provided a rational hardware solution to
microcomputing systems and microelectronics equipment for industrial and commercial uses.
In the industrial electronics and ICT market, the 19-inch subrack system in the 482,6 mm (19 in)
standard series was accepted as an effective solutio
...