Temperature rise by dielectric losses

This is the conductor temperature rise above the ambient temperature caused by dielectric losses respectively above the cable oversheath temperature for cables in tunnel.

The temperature rise caused by dielectric losses is relevant for high-voltage cables because the losses are strongly voltage dependent. If the application of system voltage occurs, then an additional transient temperature rise due to the dielectric loss has to be calculated with following assumptions:

Symbol
$\Delta \theta_{d}$
Unit
K
Formulae
$W_{d} \left(T_{d} n_{c} + n_{cc} \left(T_{4i} + T_{4ii} + T_{4iii}\right)\right)$cables in air, trough or channel
$W_{d} \left(T_{d} n_{c} + n_{cc} \left(T_{4i} + T_{4ii} + T_{4ss} v_{4}\right)\right)$cables buried
$W_{d} \left(T_{d} n_{c} + n_{cc} \left(T_{4i} + T_{4ii}\right)\right)$cables in tunnel
$W_{d} n_{c} \left(T_{4t} + T_{d}\right)$cables in tunnel (IEC 60287-2-3)
$W_{d} \left(T_{4iii} n_{cc} + T_{d} n_{c}\right)$cables subsea
$W_{d}$
Used in
$\Delta \theta_{R_{\infty}}$