Abstract
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.
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