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Thermal Resistivity of Materials
tegories-appendix-thermal-resistivity-of-materials
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Thermal Resistivity of Materials
Material
Thermal Resistivity (ρT)
Km/WIEC 60287
Insulating Materials* Paper insulation in solid type cables 6.0 6.0 Paper insulation in oil-filled cables 5.0 5.0 Paper insulation in cables with external gas pressure 5.5 Paper insulation in cables with internal gas pressure A) Pre-impregnated 5.5 5.5 B) Mass-impregnated 6.0 PE 3.5 3.5 XLPE 3.5 3.5 PPL 5.5 5.5 Polyvinyl chloride Up to and including 3kV cables 5.0 Greater than 3kV cables 6.0 EPR Up to and including 3kV cables 3.5 Greater than 3kV cables 5.0 Butyl rubber 5.0 Rubber 5.0 Protective Coverings Compounded jute and fibrous materials 6.0 Rubber sandwich protection 6.0 Polychoroprene PVC Up to and including 35kV cables 5.0 Greater than 35kV cables 6.0 PVC/Bitumen on corrugated aluminum sheaths 6.0 PE 3.5 3.5 Materials for Duct Installations Concrete 1.0 Fibre 4.8 Earthenware 1.2 PVC 6.0 PE 3.5
*For the purposes of current rating calculations, the semiconducting screening materials are assumed to have the same thermal properties as the adjacent dielectric materials.
Where plastic or elastomeric materials are used for protective coverings, the thermal resistivities shall be taken to be the same as those for the insulation grades of the materials given in this table.
