Impedance of conductor outer surface

Definition according to Cigré guide 531 chapter 4.2.1, parameter $z_1$.

Symbol
$z_{e1}$
Unit
$\Omega$/m
Formulae
$\frac{m_{e1} \rho_c}{2\pi r_{e1}} \operatorname{coth}\left(0.777m_{e1} r_{e1}\right)+\frac{0.356\rho_c}{\pi {r_{e1}}^2}$
Used in
$z_{int}$