This is the conductor temperature rise above the ambient temperature respectively above the cable oversheath temperature for cables in tunnel and for cables in trough acc. to method by Anders at al 2010.

For DC cables, the dielectric losses are zero and therefore the term $W_d*T_d$ disappears.

Symbol
$\Delta \theta_{\mathrm{c}}$
Unit
K
Formulae
$W_{\mathrm{t}} n_{\mathrm{cc}} \left(T_{\mathrm{4i}} + T_{\mathrm{4ii}} + T_{\mathrm{4iii}}\right) + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables in air
$W_{\mathrm{t}} n_{\mathrm{cc}} \left(T_{\mathrm{4i}} + T_{\mathrm{4ii}} + T_{\mathrm{4\mu}} v_{\mathrm{4}}\right) + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables buried
$W_{\mathrm{t}} n_{\mathrm{cc}} \left(T_{\mathrm{4i}} + T_{\mathrm{4ii}} + T_{\mathrm{4\mu}}\right) + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables buried where drying-out of soil is avoided
$W_{\mathrm{t}} n_{\mathrm{cc}} \left(T_{\mathrm{4i}} + T_{\mathrm{4ii}}\right) + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables in tunnel
$T_{\mathrm{4t}} W_{\mathrm{t}} n_{\mathrm{cc}} + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables in tunnel (IEC 60287-2-3)
$W_{\mathrm{t}} n_{\mathrm{cc}} \left(T_{\mathrm{4i}} + T_{\mathrm{4ii}} + T_{\mathrm{4iii}}\right) + n_{\mathrm{c}} \left(T_{\mathrm{d}} W_{\mathrm{d}} + T_{\mathrm{i}} W_{\mathrm{c}}\right)$cables in trough
$- \theta_{\mathrm{air}} + \theta_{\mathrm{c}}$cables in trough (Anders at al 2010)
$\Delta \theta_{\mathrm{0x}}$cables crossing external heat sources
Related
$\Delta \theta_{\mathrm{0x}}$
$n_{\mathrm{c}}$
$n_{\mathrm{cc}}$
$T_{\mathrm{4ii}}$
$T_{\mathrm{4\mu}}$
$\theta_{\mathrm{air}}$
$\theta_{\mathrm{c}}$
$W_{\mathrm{c}}$
$W_{\mathrm{d}}$
$W_{\mathrm{t}}$
Used in
$\Delta \theta_{\mathrm{s}}$
$\theta_{\mathrm{c}}$