IEC 62610-2:2018

Mechanical structures for electrical and electronic equipment - Thermal management for cabinets in accordance with IEC 60297 and IEC 60917 series - Part 2: Method for the determination of forced air cooling

IEC 62610-2:2018 provides for compatible methods of configuring forced air cooled cabinets assembled with associated subracks and/or chassis in accordance with the IEC 60297 and IEC 60917 series.
This document contains the following:
a) thermal interfaces of subracks and/or chassis-based equipment in a cabinet, described by:
• reference temperature,
• preferred airflow conditions,
• airflow volume conditions,
• standard air;
b) procedures for determining compatible forced airflow conditions in a cabinet by applying typical thermal interface conditions.
The drawings used are not intended to indicate product design. They are only for explanatory indications for determining forced air cooling.
Keywords: Cabinets, Subracks, Forced Air Cooling, Thermal Management

Structures mécaniques pour équipements électriques et électroniques - Gestion thermique pour les armoires conformes aux séries IEC 60297 et IEC 60917 - Partie 2: Méthode pour la détermination du refroidissement par ventilation forcée

IEC 62610-2:2018 fournit des méthodes compatibles destinées à configurer des armoires à refroidissement par ventilation forcée assemblées avec des bacs à cartes et/ou des châssis associés conformes aux séries de normes IEC 60297 et IEC 60917.
Le présent document contient ce qui suit:
a) des interfaces thermiques d’équipements composés de bacs à cartes et/ou de châssis à l’intérieur d’une armoire, décrites par:
· la température de référence,
· les conditions préférentielles de circulation d’air,
· les conditions de volume de circulation d’air,
· l'air normalisé;
b) des procédures pour déterminer des conditions de circulation d’air forcée compatibles dans une armoire en appliquant des conditions d’interface thermique typiques.
Les dessins utilisés ne sont pas destinés à indiquer la conception des produits. Ils n’ont qu’une vocation explicative pour la détermination du refroidissement par ventilation forcée.
Mots clés: armoires, bacs, refroidissement par ventilation forcée, gestion thermique

General Information

• Status: Published
• Publication Date: 15-May-2018
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: SC 48D - Mechanical structures for electrical and electronic equipment
• Drafting Committee: WG 5 - TC 48/SC 48D/WG 5
• Current Stage: PPUB - Publication issued
• Start Date: 01-Jun-2018
• Completion Date: 16-May-2018

Relations

• Revises: IEC TS 62610-2:2011 - Mechanical structures for electronic equipment - Thermal management for cabinets in accordance with IEC 60297 and IEC 60917 series - Part 2: Design guide: Method for determination of forced air-cooling structure
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62610-2
®

Edition 1.0 2018-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Mechanical structures for electrical and electronic equipment – Thermal
management for cabinets in accordance with IEC 60297 and IEC 60917 series –
Part 2: Method for the determination of forced air cooling

Structures mécaniques pour équipements électriques et électroniques – Gestion
thermique pour les armoires conformes aux séries IEC 60297 ET IEC 60917 –
Partie 2: Méthode pour la détermination du refroidissement par ventilation forcée

IEC 62610-2:2018-05(en-fr)

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IEC 62610-2

®


Edition 1.0 2018-05




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Mechanical structures for electrical and electronic equipment – Thermal

management for cabinets in accordance with IEC 60297 and IEC 60917 series –

Part 2: Method for the determination of forced air cooling



Structures mécaniques pour équipements électriques et électroniques – Gestion

thermique pour les armoires conformes aux séries IEC 60297 ET IEC 60917 –


Partie 2: Méthode pour la détermination du refroidissement par ventilation forcée













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 31.240 ISBN 978-2-8322-5692-3



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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 62610-2:2018 © IEC 2018
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Thermal conditions . 7
4.1 Baseline thermal conditions . 7
4.2 Reference temperature . 7
4.3 Syntax of surfaces of a generic subrack, chassis or cabinet . 8
4.4 Preferred airflow conditions . 9
4.5 Cabinet airflow volume and temperature rise management . 10
5 Forced air thermal flow chart for cabinet equipment . 11
5.1 General . 11
5.2 Evaluation of the actual thermal performance of subrack or chassis . 12
5.3 Cabinet airflow considerations . 12
5.4 Arrangement of subracks and/or chassis-based equipment within the cabinet . 12
5.5 Selection of cabinet mounted forced air cooling device(s) . 13
5.6 Thermal operating environment . 13
5.7 Arrangement of cabinets in a server room and preferred airflow . 15
Annex A (informative) General method of thermal design for electronic equipment . 16
A.1 Thermal resistance and thermal network model . 16
A.1.1 Thermal resistance . 16
A.1.2 Thermal network model . 16
Bibliography . 19

Figure 1 – Syntax of surfaces of a forced air cooled generic subrack or chassis to be
mounted into a cabinet . 8
Figure 2 – Syntax of surfaces of a forced air cooled generic cabinet . 9
Figure 3 – Preferred cabinet airflow patterns. 10
Figure 4 – Airflow volume management . 11
Figure 5 – Forced air thermal flow chart for cabinet equipment . 12
Figure 6 – Thermal operating environment (cabinet sectional side view) . 14
Figure 7 – Cabinet operating temperature range . 15
Figure 8 – Example of cabinet airflows in an aisle containment server room . 15
Figure A.1 – Thermal network model for a plug-in unit in subrack or chassis . 18

Table 1 – Preferred airflow pattern . 9

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IEC 62610-2:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MECHANICAL STRUCTURES FOR ELECTRICAL
AND ELECTRONIC EQUIPMENT –
THERMAL MANAGEMENT FOR CABINETS IN
ACCORDANCE WITH IEC 60297 AND IEC 60917 SERIES –

Part 2: Method for the determination of forced air cooling

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
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62610-2 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.
The text of this International Standard is based on the following documents:
FDIS Report on voting
48D/664/FDIS 48D/673/RVD

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.

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– 4 – IEC 62610-2:2018 © IEC 2018
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62610 series, published under the general title Mechanical
structures for electrical and electronic equipment – Thermal management for cabinets in
accordance with IEC 60297 and IEC 60917 series, 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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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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IEC 62610-2:2018 © IEC 2018 – 5 –
INTRODUCTION
Power dissipation of high-end servers, telecommunication equipment and electronic
controllers has been increasing rapidly. Thermal management for electronic systems has
become critical to maintain performance and reliability.
For a long time natural convection air cooling was an adequate and reliable solution. Typically,
the cooling air entered a system at the bottom and the heated air exited at the top. However,
with increasing packaging density heat dissipation of components required
“compartmentalizing” of functions within a cabinet. Individual subracks and chassis require
their own individual cooling solutions often enhanced by forced air cooling devices such as
fans.
In the absence of any guide, subrack and chassis designers typically solve their cooling
problems in a way that is best suited for their specific application leaving the cabinet system
integrator to deal with a mix of incompatible subrack and/or chassis cooling concepts.
An improper arrangement of multiple subracks and/or chassis (the equipment) in a cabinet
may cause a severe imbalance of airflow within the cabinet. Two typical undesirable factors
may be triggered by such an imbalanced airflow. The required airflow volume to each
individual cabinet mounted equipment may be inadequate for proper cooling. The temperature
of components in a cabinet mounted subrack and/or chassis may increase as the exhaust air
of one equipment increases the intake air temperature of other equipment.
This document defines the basic and principal method to implement forced air cooling in
electrical and electronic cabinets. This is applied for the thermal design of any
electrical/electronic cabinet, as well as for their set-up in machine rooms, such as data
centers using aisle containment. Cooling airflow is considered not only inside of the cabinets
but also outside of the cabinets. A variable speed fan may be optional in cabinets or
subracks/chassis, but is not regarded in this standard.
The intention of this document is to guide the subrack and/or chassis system designer, the
cabinet integrator and also the data centre system integrator who deploys equipment cabinets
in the machine room to provide for compatible forced air cooling solutions.
This document is based on the mechanical structures as defined in the IEC 60297 and
IEC 60917 series of standards.

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– 6 – IEC 62610-2:2018 © IEC 2018
MECHANICAL STRUCTURES FOR ELECTRICAL
AND ELECTRONIC EQUIPMENT –
THERMAL MANAGEMENT FOR CABINETS IN
ACCORDANCE WITH IEC 60297 AND IEC 60917 SERIES –

Part 2: Method for the determination of forced air cooling



1 Scope
This part of IEC 62610 provides for compatible methods of configuring forced air cooled
cabinets assembled with associated subracks and/or chassis in accordance with the
IEC 60297 and IEC 60917 series.
This document contains the following:
a) thermal interfaces of subracks and/or chassis-based equipment in a cabinet, described by:
• reference temperature,
• preferred airflow conditions,
• airflow volume conditions,
• standard air;
b) procedures for determining compatible forced airflow conditions in a cabinet by applying
typical thermal interface conditions.
The drawings used are not intended to indicate product design. They are only for explanatory
indications for determining forced air cooling.
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 60917-1, Modular order for the development of mechanical structures for electronic
equipment practices – Part 1: Generic standard
3 Terms and definitions
For the purposes of this document, terms and definitions of IEC 60917-1 as well as the
following 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
3.1
forced air cooling
cooling system in which the air is moved by external power

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IEC 62610-2:2018 © IEC 2018 – 7 –
[SOURCE: IEC 60050-811:1991, 811-22-06]
3.2
reference temperature
initial internal temperature of the equipment
Note 1 to entry: "Reference temperature" of the subrack and/or chassis can be considered as equivalent to its
intake air temperature.
3.3
forced air cooling device
device that moves air often called a fan
3.4
standard air
3
air with density of 1,2 kg/m , a relative humidity of 50 %, a temperature of 20 °C, a pressure
of 101,3 kPa, and a specific heat capacity of 1 005 J/(kg∙K)
Note 1 to entry: These values are aligned with the fan industry specifications, common test practices and
electronic industry expectations.
3.5
total airflow volume of equipment

F
3−n
∑
combined air volume as produced by the forced air cooling devices of the subrack(s) and
chassis in the cabinet
Note 1 to entry: F means an airflow volume of a subrack or chassis. The suffix "n" means an identifier of a
3
subrack or chassis in the cabinet.
3.6
airflow volume of the cabinet
F
4
airflow volume produced by the empty cabinet mounted forced air cooling devices
3.7
ambient temperature
average temperature of air or another medium in the vicinity of the equipment
Note 1 to entry: For this standard, equipment is subracks and/or chassis-based equipment.
4 Thermal conditions
4.1 Baseline thermal conditions
In order to enable reproducible and comparable values, standard air is defined at the air inlet
to be used for the determination of the thermal capability and requirement parameters of
products.
4.2 Reference temperature
The thermal operating temperature of subrack and chassis in the cabinet should be defined at
the air inlet, and this temperature is called reference temperature in this document.
Reference temperature is defined as a starting point for the rise in the internal temperature of
the subracks and/or chassis-based equipment, and is equivalent to the intake air temperature
of the subrack and/or chassis. The reference temperature will influence the temperature of the
equipment in the subrack and/or chassis.

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– 8 – IEC 62610-2:2018 © IEC 2018
For a typical configuration, which consists of a subrack and a forced air cooling device,
temperatures of internal air and inside components of the subrack are determined as certain
values from the reference temperature. And the reference temperature of the subrack can be
considered as equivalent to its intake air temperature, because the heat dissipating path of
the forced air cooling is dependent on ventilation characteristics of the subrack (see Annex A).
The air intake is the initial point of an upstream airflow where airflows into the subrack and/or
chassis to cool its inside. The intake air temperature of the subrack and/or chassis(T ) as
3-nr
supplied by the ambient temperature (T ) could be identical (see Figure 6). Generally, the
4
intake air temperature is measured at a position 30 mm to 50 mm away from the casing of the
equipment to avoid the influence of heat radiation. At the air intake opening, if the
temperature is not considered as homogeneous because the opening is so wide, several
positions (3 to 5) should be defined as reference temperature positions, and the average
temperature should be taken as the intake air temperature.
4.3 Syntax of surfaces of a generic subrack, chassis or cabinet
In order to define airflow patterns of equipment, the syntax of the outer surfaces of a subrack
and/or chassis-based equipment mounted within a cabinet is shown in Figure 1 and the
syntax of the outer surfaces of a forced air cooling generic cabinet is shown in Figure 2.
IEC

Figure 1 – Syntax of surfaces of a forced air cooled generic subrack or chassis
to be mounted into a cabinet

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IEC 62610-2:2018 © IEC 2018 – 9 –

IEC
Figure 2 – Syntax of surfaces of a forced air cooled generic cabinet
4.4 Preferred airflow conditions
In order to facilitate an efficient cabinet airflow design, it is necessary to define the preferred
airflow pattern of the cabinet mounted equipment. It is important that the cold air entry is not
contaminated by the hot air exit (separation of the air entry path and the air exit path). The
essential principles of the cooling airflow direction are front to rear and bottom to top.
The complete syntax of airflow pattern in Table 1 is as follows:
Intake definition [ + additional intake definition] → exhaust definition [+ additional exhaust
definition]
The intake and exhaust definition corresponds to the syntax of the surfaces as shown in
Figure 1 and Figure 2.
Table 1 – Preferred airflow pattern
b
Airflow pattern within subrack or Airflow pattern within cabinet
a
chassis-based equipment
F → R F →R2
F+B →R F→T
F+B → T
F+B → T+R1
F+B → T+R2
F+B → R1+R2
a
Subracks or chassis with forced air cooling devices.
b
Cabinets with forced air cooling devices.

Subracks and chassis which do not comply to the preferred airflow pattern as described in this
document should provide for additional airflow management devices such as deflectors.
These additional deflectors should bring the equipment in line with a preferred airflow pattern.

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– 10 – IEC 62610-2:2018 © IEC 2018
The following figures illustrate preferred airflow patterns within a cabinet as per Table 1.
The arrangements shown in Figure 3 are typical only.

IEC IEC
IEC


a) F → R2 b) F → T c) F + B → T
IEC IEC IEC

d) F + B → T + R1 e) F + B → T + R2 d) F + B → R1 + R2
Figure 3 – Preferred cabinet airflow patterns
4.5 Cabinet airflow volume and temperature rise management
A cabinet with forced air cooling devices shall have enough airflow volume to maintain the
cooling capacities of various types of cabinet mounted subracks or chassis that contain their
own forced air cooling devices.
The cabinet with one or more such subracks and/or chassis shall have an exhaust air
ventilation capacity more than or equal to the sum of subracks’ and/or chassis’ airflow
volumes. This means that the cabinet does not impede the respective subracks' or chassis'
ventilation capacities.
The airflow volume of the cabinet mounted forced air cooling devices (F ) shall be sized to
4
match the combined air volume as produced by the forced air cooling devices of the
subrack(s) (F ) and chassis (F ) in the cabinet (see Figure 4).
3-2 3-1
The power dissipation of air-exit fans should be considered to evaluate the exhaust air
temperature rise of the equipped cabinet in order to measure the airflow volume.
F ≤ F
3−n 4
∑

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IEC 62610-2:2018 © IEC 2018 – 11 –
where
is the total airflow volume of equipment;
F
3−n
∑
F is the airflow volume of the cabinet.
4
IEC

Figure 4 – Airflow volume management
5 Forced air thermal flow chart for cabinet equipment
5.1 General
The flow chart as shown in Figure 5 identifies the forced airflow procedure for cabinet
equipment.
The details of each step in the flow chart are explained in the following subclauses.

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– 12 – IEC 62610-2:2018 © IEC 2018

IEC
Figure 5 – Forced air thermal flow chart for cabinet equipment
5.2 Evaluation of the actual thermal performance of subrack or chassis
For the thermal management of cabinet mounted subracks and/or chassis-based equipment, it
is important to take the following into account:
a) the airflow pattern (See Table 1),
b) the airflow volume,
c) the operating temperature range,
d) the temperature rise limitation.
5.3 Cabinet airflow considerations
The airflow in the application specific operating environment where the cabinet is installed
should be investigated. The airflow pattern for the cabinet is chosen from the related Table 1.
5.4 Arrangement of subracks and/or chassis-based equipment within the cabinet
Ideally, all cabinet mounted subracks and/or chassis-based equipment have the same
compatible airflow pattern chosen from Table 1. Incompatible airflow pattern of an individual
subracks and/or chassis-based equipment should be redirected by suitable airflow dividers or
airflow deflector panels in order to prevent cabinet airflow imbalance such as re-circulation
and to control the airflow within the cabinet.

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IEC 62610-2:2018 © IEC 2018 – 13 –
5.5 Selection of cabinet mounted forced air cooling device(s)
The cabinet mounted forced air cooling device(s) shall be chosen to ensure a cabinet airflow
volume (F ) that balances or exceeds the combined airflow volume (F ) provided by the
4 3-n
subrack(s) and /or chassis.
F ≤ F
∑ 3−n 4

where
F is the airflow volume of subrack or chassis in the cabinet;
3−n
F is the airflow volume of
...