Thickness conductor—sheath

Insulation thickness between conductors and sheath used to calculate $T_1$ with following considerations:

For multi-core cables, $t_1$ is up to the sheath and $t_2$ is between sheath and armour.
A tape screen is considered equivalent to a sheath, so for single-core cables with a tape screen and no sheath and for multi-core cables with a common screen and no sheath, the screen serving is added to $t_2$.
A wired screen is not relevant for the calculation.
For multi-core cables with separate sheaths, the filler is part of $t_2$.

Type of screen/sheath of multi-core cables

SS: with separate screen and separate sheaths
SC: with separate screen and common sheath
CC: with common screen and common sheath

Symbol

$t_1$

Unit

mm

Formulas

$t_i+t_{scb}+t_{scs}+\frac{H_{sh}+\Delta H}{2}$	single-core cables
$t_i+t_{scb}+t_{scs}+\frac{H_{sh}+\Delta H}{2}$	multi-core cables, type SS
$t_i+t_{scb}+t_{scs}+t_f+\frac{H_{sh}+\Delta H}{2}$	multi-core cables, type SC
$t_i+t_f+t_{scb}+t_{scs}+\frac{H_{sh}+\Delta H}{2}$	multi-core cables, type CC
$t_i+t_{scb}+t_{scs}+t_f$	multi-core cables, without screen & sheath
$\frac{D_{sc}}{2}-\frac{d_c}{2}+t_{scs}$	pipe-type cables

Related

$d_c$

External diameter conductor [mm]

$D_{sc}$

Diameter over screen [mm]

$\Delta H$

Correction depth of corrugation [mm]

$H_{sh}$

Depth of corrugation [mm]

$t_f$

Thickness of filler/belt insulation [mm]

$t_i$

Thickness insulation [mm]

$t_{scb}$

Thickness screen bedding [mm]

$t_{scs}$

Thickness screen serving [mm]

Used in

$G_1$

Geometric factor $G_1$

$T_1$

Thermal resistance conductor—sheath [K.m/W]

$t_{1,t}$

Thickness conductor—sheath, transient [mm]

$X_G$

$Y_G$

$Y_K$