scope:

NPR-IEC/TR 60890 specifies a method of temperature-rise verification of low-voltage switchgear and controlgear ASSEMBLIES by calculation. The method is applicable to enclosed ASSEMBLIES or partitioned sections of ASSEMBLIES without forced ventilation. It is not applicable where temperature rise verification to the relevant product standard of the IEC 61439 series has been established NOTE 1 The influence of the materials and wall thicknesses usually used for enclosures can have some effect on the steady state temperatures. However, the generalised approach used in this technical report ensures it is applicable to enclosures made of sheet steel, sheet aluminium, cast iron, insulating material and the like. The proposed method is intended to determine the temperature rise of the air inside the enclosure.