Transient temperature rise of outer surface

The transient response of the cable environment is calculated by an exponential integral formula which is the direct transient equivalent of the steady-state procedure adopted in IEC 60287, for groups of separate cables.

Note: The parameters $D_o$ and $L_{cm}$ are in meters.

Symbol
$\Delta \theta_{e_{t}}$
Unit
K
Formulae
$\frac{W_{I} \rho_{4} \left(- \operatorname{expi}{\left(- \frac{D_{o}^{2}}{16 \delta _{soil} \tau} \right)} + \operatorname{expi}{\left(- \frac{L_{cm}^{2}}{\delta _{soil} \tau} \right)}\right)}{4 \pi}$
Related
$D_{o}$
$\delta _{soil}$
$L_{cm}$
$\rho_{4}$
Used in
$\Delta \theta_{t}$