Thermal resistance armour bedding

Symbol
$T_{ab}$
Unit
K.m/W
Formulas
$\frac{\rho_{ab}}{2\pi} \ln\left(\frac{D_{ab}}{F_x D_{shj}}\right)$multi-core cables type SS
$\frac{\rho_{ab}}{2\pi} \ln\left(\frac{D_{ab}}{D_{shj}-\left(H_{sh}+\Delta H\right)}\right)$otherwise
$T_{ab,1}+T_{ab,2}$double layer armour CIGRE TB 880 Guidance Point 15