Internal thermal resistance for current losses

Symbol
$T_{int}$
Unit
K.m/W
Formulae
$\frac{T_1}{n_c}+\left(1+\lambda_1\right) T_2+\left(1+\lambda_1+\lambda_2+\lambda_3\right) T_3$AC cables
$\frac{T_1}{n_c}+T_2+T_3$DC cables up to 5 kV, not concentric
$\frac{T_1}{n_c}+\left(1+\lambda_1\right) T_{prot}$PAC/GIL
$\frac{T_1}{n_c}+\left(1+\lambda_1\right) T_2$Cables subsea
$\frac{7}{18} T_1$Three-core cables in riser (Hartlein & Black)