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Thermal resistance of jacket

Symbol
$T_3$
Unit
K.m/W
Formulae
$\frac{\rho_j}{2\pi} \ln\left(\frac{D_j}{D_j-2t_3}\right)$general case
$1.6T_3$Single-core cables, part-metallic sheathed/metallic sheathed, trefoil
$\frac{1}{2k_{prot} \pi} \ln\left(\frac{D_{prot}}{D_{encl}}\right)$PAC/GIL
Related
$D_{encl}$
Outer diameter of enclosure [m]
$D_j$
Diameter over jacket [mm]
$D_{prot}$
Diameter of protective cover [m]
$k_{prot}$
Thermal conductivity of protective cover [W/(m.K)]
$\pi$
Archimedes' constant $\pi$
$\rho_j$
Thermal resistivity of jacket material [K.m/W]
$t_3$
Thickness of serving over armour [mm]
Used in
$\delta \theta_c$
Ohmic steady-state temperature rise [K]
$I_c$
Conductor current [A]
$Q_{B,ab}$
Element B of two-part thermal circuit of armour bedding [J/(m.K)]
$Q_{B,f}$
Element B of two-part thermal circuit, filler [J/(m.K)]
$Q_{B,j}$
Element B of two-part thermal circuit, jacket [J/(m.K)]
$T_B$
Element B of equivalent thermal circuit [K.m/W]
$T_d$
Internal thermal resistance for dielectric losses [K.m/W]
$T_{eq}$
Equivalent thermal resistance [K.m/W]
$T_{int}$
Internal thermal resistance for current losses [K.m/W]
$T_r$
Total thermal resistance [K.m/W]
$T_{tot}$
Total thermal resistance, transient [K.m/W]
$\theta_{c,z}$
Conductor temperature at z [°C]
$\theta_e$
External temperature of the object [°C]
$U_{wall}$
OHTC of pipe wall [W/(K.m$^2$)]