Impedance at transition overhead line to underground cable

Definition according to Cigré guide 531 chapter 4.2.4.2

Symbol
$Z_{as}$
Unit
$\Omega$/m
Formulae
$Z_{sw} L_{link}+\frac{\sqrt{\left(Z_{sw} L_{link}\right)^2+4R_r Z_{sw} L_{link}}}{2}$exact
$\sqrt{R_r Z_{sw} L_{link}}$approximation
Related
$L_{link}$
$Z_{sw}$