DIN EN IEC 61439-1 Beiblatt 2:2025-02

This document describes a method for calculating air heating in enclosures of low-voltage switchgear and control gear assemblies or similar products in accordance with the relevant standards. There are no restrictions in accordance with the scope of the document. The standard differs from DIN EN 61439-1 Supplement 2 (VDE 0660-600-1 Supplement 2):2016-02 as follows: a) based on IEC 61439-1:2020; b) addition of individual annexes to assist with technical explanations relating to: effect of uneven energy distribution, additional heating due to solar radiation, effect of different enclosure materials, effect of different natural ventilation controls, control of forced ventilation, calculation of power loss, influence that an adjacent wall can have on the cooling surface(s) of the switchgear and control gear assemblies; c) maximum temperature limit inside a switchgear and control gear assembly; d) validity of the calculation extended from 3 150 A to 3 200 A; e) addition of an algebraic equation to the various characteristic curves contained in this document. The document is primarily applicable to switchgear and control gear assemblies in enclosed construction or to fields of switchgear and control gear assemblies divided by partitions without forced ventilation. However, this document provides some technical information that can be used to adapt the method for use with forced ventilation. The results achieved by applying this method are directly influenced by the accuracy of the evaluation of the power losses used as input values for the thermal calculations.