IEC TR 60890:2022
(Main)A method of temperature-rise verification of low-voltage switchgear and controlgear assemblies by calculation
A method of temperature-rise verification of low-voltage switchgear and controlgear assemblies by calculation
IEC TR 60890:2022 specifies a method of air temperature-rise calculation inside enclosures for low-voltage switchgear and controlgear assemblies or similar products in accordance with their respective standard. The method is primarily applicable to enclosed assemblies or partitioned sections of assemblies without forced ventilation. This third edition cancels and replaces the second edition published in 2014. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- alignment with IEC 61439-1:2020;
- addition of individual annexes for guidance of technical explanations related to:
--- effect of an uneven power distribution;
--- additional temperature-rise due to solar radiation;
--- effect of different enclosure materials;
--- effect of different natural ventilation management;
--- forced ventilation management;
--- power losses calculation;
--- impact of an adjacent wall can have on the assembly cooling surface(s);
- maximum internal ambient temperature limit into an assembly;
- validity area of the calculation extended from 3 150 A to 3 200 A;
- addition of an algebraic equation to the different curves included in the document.
Méthode de vérification par calcul des échauffements pour les ensembles d'appareillages à basse tension
L'IEC TR 60890:2022 spécifie une méthode de calcul des échauffements de l'air à l'intérieur d'une enveloppe pour les ensembles d'appareillages à basse tension ou produits analogues selon leur norme respective.
La méthode s'applique principalement aux ensembles sous enveloppe ou aux sections compartimentées des ensembles sans ventilation forcée.
Cette troisième édition annule et remplace la deuxième édition parue en 2014. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
alignement sur l'IEC 61439-1:2020;
ajout d'annexes spécifiques qui contiennent à titre de recommandations des explications techniques concernant:
l'effet d'une répartition de puissance non uniforme;
l'échauffement supplémentaire dû au rayonnement solaire;
l'effet des différents matériaux d'enveloppe;
l'effet des différents moyens de gestion par ventilation naturelle;
la gestion par ventilation forcée;
le calcul des puissances dissipées;
l'impact que peut avoir une paroi adjacente sur la ou les surfaces de refroidissement de l'ensemble;
ajout d'une limite maximale pour la température ambiante interne d'un ensemble;
extension du domaine de validité du calcul de 3 150 A à 3 200 A;
ajout d'une équation algébrique pour les différentes courbes incluses dans le document.
La présente version bilingue (2023-01) correspond à la version anglaise monolingue publiée en 2022-09.
La version française de cette norme n'a pas été soumise au vote.
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IEC TR 60890 ®
Edition 3.0 2022-09
TECHNICAL
REPORT
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
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.
IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
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.
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IEC TR 60890 ®
Edition 3.0 2022-09
TECHNICAL
REPORT
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-5762-3
– 2 – IEC TR 60890:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Verification conditions . 9
5 Calculation method . 9
5.1 Assumptions made in this calculation . 9
5.2 Necessary information . 10
5.3 Calculation procedure . 10
5.3.1 General . 10
5.3.2 Determination of the effective cooling surface A of the enclosure . 10
e
5.3.3 Determination of the internal temperature-rise ∆t of the air at mid-
0,5
height of the enclosure . 10
5.3.4 Determination of the internal temperature-rise ∆t of air at the top of
1,0
the enclosure . 11
5.3.5 Characteristic curve for temperature-rise of air inside enclosure . 11
5.4 Maximum internal air temperature limits . 13
6 Further considerations . 13
6.1 General . 13
6.2 Guidance on the effects of an uneven power distribution . 13
6.3 Guidance on the additional temperature-rise effect due to solar radiation . 14
7 Evaluation of the design . 15
Annex A (informative) Examples for the calculation of the temperature-rise of air
inside enclosures . 26
A.1 Example 1 . 26
A.2 Example 2 . 29
Annex B (informative) Guidance on the effects of an uneven power distribution . 33
B.1 Horizontal partition . 33
B.2 Calculation of internal air temperature-rise for assemblies with ventilation
openings with even power distribution and less than 50 % perforation in
horizontal partitions . 33
B.3 Calculation of internal air temperature-rise with an uneven power distribution . 34
Annex C (informative) Guidance on the additional temperature-rise effect due to solar
radiation . 35
C.1 General . 35
C.2 Solar radiation phenomena . 35
C.3 Solar radiation – consequences for thermal calculation . 36
C.4 Solar radiation of enclosures with air ventilation openings . 37
Annex D (informative) Guidance on the effect of different enclosure materials,
construction and finishes . 38
D.1 General . 38
D.2 Validity criteria . 38
D.3 Material of enclosure . 38
D.4 Results . 38
Annex E (informative) Guidance on the effects of different natural ventilation
arrangements. 40
Annex F (informative) Guidance on forced ventilation management . 42
F.1 General . 42
F.2 Forced ventilation installation system . 42
F.3 Installation considerations . 42
Annex G (informative) Power loss values calculation . 44
G.1 General . 44
G.2 Power losses of low-voltage switchgear and controlgear . 44
G.3 Power losses of conductors connecting low-voltage switchgear and
controlgear . 44
G.4 Power losses of busbars . 45
G.5 Power losses of electronic devices . 45
Annex H (informative) Guidance on the impact of an adjacent wall on the assembly
cooling surfaces . 46
Annex I (informative) Operating current and power loss of copper conductors. 48
Annex J (informative) Guidance to magnetic and eddy-current power losses. 53
Annex K (informative) Forced ventilation airflow calculation . 54
K.1 General . 54
K.2 Ventilation airflow calculation . 55
Bibliography . 57
Figure 1 – Temperature-rise characteristic curve for enclosures with A exceeding
e
1,25 m . 12
Figure 2 – Temperature-rise characteristic curve for enclosures with A not exceeding
e
1,25 m . 13
Figure 3 – Enclosure constant k for enclosures without ventilation openings, with an
effective cooling surface A > 1,25 m . 18
e
Figure 4 – Temperature distribution factor c for enclosures without ventilation openings
and with an effective cooling surface A > 1,25 m . 19
e
Figure 5 – Enclosure constant k for enclosures with ventilation openings and an
effective cooling surface A > 1,25 m . 20
e
Figure 6 – Temperature distribution factor c for enclosures with ventilation openings
and an effective cooling surface A > 1,25 m . 21
e
Figure 7 – Enclosure constant k for enclosures without ventilation openings and with
an effective cooling surface A ≤ 1,25 m . 22
e
Figure 8 – Temperature distribution factor c for enclosures without ventilation
openings and with an effective cooling surface A ≤ 1,25 m . 23
e
Figure 9 – Calculation of temperature-rise of air inside enclosures . 25
Figure A.1 – Example 1, calculation for an enclosure with exposed side faces without
ventilation openings and without internal horizontal partitions . 26
Figure A.2 – Example 1, calculation for a single enclosure . 28
Figure A.3 – Example 2, calculation for an enclosure for wall-mounting with ventilation
openings . 29
Figure A.4 – Example 2, calculation for one enclosure half . 30
– 4 – IEC TR 60890:2022 © IEC 2022
Figure A.5 – Example 2, calculation for an enclosure for wall-mounting with ventilation
openings . 32
Figure B.1 – Examples of assemblies with horizontal partitions . 33
Figure B.2 – Temperature-rise verification of a higher-power circuit . 34
Figure C.1 – Solar radiation phenomena . 35
Figure C.2 – Interpolation curve . 36
Figure D.1 – Results of comparison tests . 39
Figure E.1 – Examples of crossing diagonal installation . 40
Figure E.2 – Effect of additional filters . 41
Figure F.1 – Examples of forced ventilation arrangements . 43
Figure H.1 – Wall-mounted assembly . 46
Figure H.2 – Floor-standin
...
IEC TR 60890 ®
Edition 3.0 2022-09
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
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.
IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
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 corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
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IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 19 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TR 60890 ®
Edition 3.0 2022-09
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-5822-4
– 2 – IEC TR 60890:2022 RLV © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Verification conditions for application. 9
5 Calculation method . 10
5.1 Assumptions made in this calculation . 10
5.2 Necessary information . 10
5.3 Calculation procedure . 11
5.3.1 General . 11
5.3.2 Determination of the effective cooling surface A of the enclosure . 11
e
5.3.3 Determination of the internal temperature-rise ∆t of the air at mid-
0,5
height of the enclosure . 11
5.3.4 Determination of the internal temperature-rise ∆t of air at the top of
1,0
the enclosure . 11
5.3.5 Characteristic curve for temperature-rise of air inside enclosure . 12
5.4 Maximum internal air temperature limits . 14
6 Further considerations . 14
6.1 General . 14
6.2 Guidance on the effects of an uneven power distribution . 14
6.3 Guidance on the additional temperature-rise effect due to solar radiation . 14
7 Evaluation of the design . 15
Annex A (informative) Examples for the calculation of the temperature-rise of air
inside enclosures . 34
A.1 Example 1 . 34
A.2 Example 2 . 38
Annex B (informative) Guidance on the effects of an uneven power distribution . 43
B.1 Horizontal partition . 43
B.2 Calculation of internal air temperature-rise for assemblies with ventilation
openings with even power distribution and less than 50 % perforation in
horizontal partitions . 43
B.3 Calculation of internal air temperature-rise with an uneven power distribution . 44
Annex C (informative) Guidance on the additional temperature-rise effect due to solar
radiation . 45
C.1 General . 45
C.2 Solar radiation phenomena . 45
C.3 Solar radiation – consequences for thermal calculation . 46
C.4 Solar radiation of enclosures with air ventilation openings . 47
Annex D (informative) Guidance on the effect of different enclosure materials,
construction and finishes . 48
D.1 General . 48
D.2 Validity criteria . 48
D.3 Material of enclosure . 48
D.4 Results . 48
Annex E (informative) Guidance on the effects of different natural ventilation
arrangements. 50
Annex F (informative) Guidance on forced ventilation management . 52
F.1 General . 52
F.2 Forced ventilation installation system . 52
F.3 Installation considerations . 52
Annex G (informative) Power loss values calculation . 54
G.1 General . 54
G.2 Power losses of low-voltage switchgear and controlgear . 54
G.3 Power losses of conductors connecting low-voltage switchgear and
controlgear . 54
G.4 Power losses of busbars . 55
G.5 Power losses of electronic devices . 55
Annex H (informative) Guidance on the impact of an adjacent wall on the assembly
cooling surfaces . 56
Annex I (informative) Operating current and power losses of copper conductors . 58
Annex J (informative) Guidance to magnetic and eddy-current power losses. 63
Annex K (informative) Forced ventilation airflow calculation . 64
K.1 General . 64
K.2 Ventilation airflow calculation . 65
Bibliography . 67
Figure 1 – Temperature-rise characteristic curve for enclosures with A exceeding
e
1,25 m . 13
Figure 2 – Temperature-rise characteristic curve for enclosures with A not exceeding
e
1,25 m . 13
Figure 3 – Enclosure constant k for enclosures without ventilation openings, with an
effective cooling surface A > 1,25 m . 19
e
Figure 4 – Temperature distribution factor c for enclosures without ventilation openings
and with an effective cooling surface A > 1,25 m . 21
e
Figure 5 – Enclosure constant k for enclosures with ventilation openings and an
effective cooling surface A > 1,25 m . 23
e
Figure 6 – Temperature distribution factor c for enclosures with ventilation openings
and an effective cooling surface A > 1,25 m . 25
e
Figure 7 – Enclosure constant k for enclosures without ventilation openings and with
an effective cooling surface A ≤ 1,25 m . 28
e
Figure 8 – Temperature distribution factor c for enclosures without ventilation openings
and with an effective cooling surface A ≤ 1,25 m . 30
e
Figure 9 – Calculation of temperature-rise of air inside enclosures . 33
Figure A.1 – Example 1, calculation for an enclosure with exposed side faces without
ventilation openings and without internal horizontal partitions . 34
Figure A.2 – Example 1, calculation for a single enclosure . 37
Figure A.3 – Example 2, calculation for an enclosure for wall-mounting with ventilation
openings . 38
Figure A.4 – Example 2, calculation for one enclosure half . 39
– 4 – IEC TR 60890:2022 RLV © IEC 2022
Figure A.5 – Example 2, calculation for an enclosure for wall-mounting with ventilation
openings . 42
Figure B.1 – Examples of assemblies with horizontal partitions . 43
Figure B.2 – Temperature-rise verification of a higher-power circuit . 44
Figure C.1 – Solar radiation phenomena . 45
Figure C.2 – Interpolation curve . 46
Figure D.1 – Results of comparison tests . 49
Figure E.1 – Examples of crossing diagonal installation . 50
Figure E.2 – Effect of additional filters . 51
Figure F.1 – Examples of forced ventilation arrangements . 53
Figure H.1 – Wall-mounted assembly . 56
Figure H.2 – Floor-standing assembly .
...
IEC TR 60890 ®
Edition 3.0 2022-09
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
Méthode de vérification par calcul des échauffements pour les ensembles
d'appareillages à basse tension
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.
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3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
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 corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
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The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
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IEC TR 60890 ®
Edition 3.0 2022-09
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
colour
inside
A method of temperature-rise verification of low-voltage switchgear and
controlgear assemblies by calculation
Méthode de vérification par calcul des échauffements pour les ensembles
d'appareillages à basse tension
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-6368-6
– 2 – IEC TR 60890:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Verification conditions . 9
5 Calculation method . 9
5.1 Assumptions made in this calculation . 9
5.2 Necessary information . 10
5.3 Calculation procedure . 10
5.3.1 General . 10
5.3.2 Determination of the effective cooling surface A of the enclosure . 10
e
5.3.3 Determination of the internal temperature-rise ∆t of the air at mid-
0,5
height of the enclosure . 10
5.3.4 Determination of the internal temperature-rise ∆t of air at the top of
1,0
the enclosure . 11
5.3.5 Characteristic curve for temperature-rise of air inside enclosure . 11
5.4 Maximum internal air temperature limits . 13
6 Further considerations . 13
6.1 General . 13
6.2 Guidance on the effects of an uneven power distribution . 13
6.3 Guidance on the additional temperature-rise effect due to solar radiation . 14
7 Evaluation of the design . 15
Annex A (informative) Examples for the calculation of the temperature-rise of air
inside enclosures . 26
A.1 Example 1 . 26
A.2 Example 2 . 29
Annex B (informative) Guidance on the effects of an uneven power distribution . 33
B.1 Horizontal partition . 33
B.2 Calculation of internal air temperature-rise for assemblies with ventilation
openings with even power distribution and less than 50 % perforation in
horizontal partitions . 33
B.3 Calculation of internal air temperature-rise with an uneven power distribution . 34
Annex C (informative) Guidance on the additional temperature-rise effect due to solar
radiation . 35
C.1 General . 35
C.2 Solar radiation phenomena . 35
C.3 Solar radiation – consequences for thermal calculation . 36
C.4 Solar radiation of enclosures with air ventilation openings . 37
Annex D (informative) Guidance on the effect of different enclosure materials,
construction and finishes . 38
D.1 General . 38
D.2 Validity criteria . 38
D.3 Material of enclosure . 38
D.4 Results . 38
Annex E (informative) Guidance on the effects of different natural ventilation
arrangements. 40
Annex F (informative) Guidance on forced ventilation management . 42
F.1 General . 42
F.2 Forced ventilation installation system . 42
F.3 Installation considerations . 42
Annex G (informative) Power loss values calculation . 44
G.1 General . 44
G.2 Power losses of low-voltage switchgear and controlgear . 44
G.3 Power losses of conductors connecting low-voltage switchgear and
controlgear . 44
G.4 Power losses of busbars . 45
G.5 Power losses of electronic devices . 45
Annex H (informative) Guidance on the impact of an adjacent wall on the assembly
cooling surfaces . 46
Annex I (informative) Operating current and power loss of copper conductors. 48
Annex J (informative) Guidance to magnetic and eddy-current power losses. 53
Annex K (informative) Forced ventilation airflow calculation . 54
K.1 General . 54
K.2 Ventilation airflow calculation . 55
Bibliography . 57
Figure 1 – Temperature-rise characteristic curve for enclosures with A exceeding
e
1,25 m . 12
Figure 2 – Temperature-rise characteristic curve for enclosures with A not exceeding
e
1,25 m . 13
Figure 3 – Enclosure constant k for enclosures without ventilation openings, with an
effective cooling surface A > 1,25 m . 18
e
Figure 4 – Temperature distribution factor c for enclosures without ventilation openings
and with an effective cooling surface A > 1,25 m . 19
e
Figure 5 – Enclosure constant k for enclosures with ventilation openings and an
effective cooling surface A > 1,25 m . 20
e
Figure 6 – Temperature distribution factor c for enclosures wi
...
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