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Thermal resistance of armour bedding

Thermal resistance of the bedding between sheath and armour consists of the bedding between the sheath and the first armour layer plus the separation material between the first and second armour layer if any. In case of three-core cables with jacket around each core, this is the thermal resistance of the filler between sheath and armour for three-core cables type SS with sheath. This includes the thermal resistance of the jacket around each core and of the armour bedding.

Symbol
$T_2$
Unit
K.m/W
Formulae
$\frac{\rho_{ab}}{2\pi} \ln\left(1+\frac{2t_2}{D_{sh}-\Delta d_{sh}}\right)$Single-core cables or multi-core cables with common sheath
$\frac{\rho_f}{6\pi} G_2$Three-core cables type SS with sheath
$T_{spf}+T_{ab}$Pipe-type cables
Related
$D_{sh}$
Diameter over sheath [mm]
$\Delta d_{sh}$
Depth of corrugation [mm]
$G_2$
Geometric factor $G_2$ for cables with separate sheaths
$\pi$
Archimedes' constant $\pi$
$\rho_{ab}$
Thermal resistivity of armour bedding [K.m/W]
$\rho_f$
Thermal resistivity of filler [K.m/W]
$t_2$
Thickness of bedding under armour [mm]
$T_{ab}$
Thermal resistance of armour bedding [K.m/W]
$T_{spf}$
Thermal resistance of steel pipe filling [K.m/W]
Used in
$I_c$
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)]
$R_{c3}$
Thermal resistance, 3rd loop [K.m/W]
$T_B$
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]
$\theta_{ar}$
Temperature of armour [°C]
$\theta_{c,z}$
Conductor temperature at z [°C]
$\theta_e$
External temperature of the object [°C]
$\theta_f$
Temperature of filler for multi-core cables type SS with sheath [°C]
$\theta_{sp}$
Temperature of steel pipe [°C]