Heat flows out of the metallic conductor and into the adjacent insulation or surrounding medium.
is an international standard published by the International Electrotechnical Commission (IEC). Its official title is generally listed as: “Calculation of thermally permissible short-circuit currents, taking into account non-adiabatic heating effects.”
If you are looking for specific implementation reports or sizing guides, these PDF documents provide practical applications of the standard: iec 60949 pdf free top download
The standard's approach is to calculate a "modifying factor" and then multiply it by the adiabatic current. By taking heat transfer into account, the method allows engineers to safely justify reducing the cross-section of a cable's metallic screen by compared to the purely adiabatic calculation. This optimization, while seemingly small, can lead to significant material cost savings in large-scale projects without compromising safety.
You can view a free sample of the IEC 60949:1988/AMD1:2008 Amendment which includes the table of contents and scope. Heat flows out of the metallic conductor and
The standard modifies the classic adiabatic formula to include a correction factor for heat loss. The General Formula
: A constant depending on the material (e.g., for copper, 148 for aluminum). θitheta sub i θftheta sub f : Initial and final (limit) temperatures. Related Technical Resources By taking heat transfer into account, the method
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