Historical
IEC/TR 60890 Ed. 1.0 b:1987
A method of temperature-rise assessment by extrapolation for partially type-tested assemblies (PTTA) of low-voltage switchgear and controlgear
The proposed method is applicable to enclosed PTTA or partitioned sections of PTTA without forced ventilation. It is intended to determine the temperature rise of the air inside the enclosure.
International Electrotechnical Commission [iec]