Transient thermal resistance for weekly load

Effective transient thermal resistance in the earth for weekly load (transient period $\tau$ of 7 days):

In the majourity of practical cases, the load variations will exhibit a more complex pattern than the one described by a daily load cycle, such as for example, loading of cables is usually much lighter during the weekend than during the weekdays.

Symbol
$T_{4w}$
Unit
K.m/W
Formulae
$\frac{\rho_{4} \ln{\left(\frac{D_{x_{w}}}{Do_{d}} \right)}}{2 \pi}$
$\rho_{4}$
Used in
$T_{4\mu}$