Impedance of sheath inner surface

Definition according to Cigré guide 531 chapter 4.2.2.5 for composite screen and sheath ($z_7$)

Symbol

$\mathscr{z}_{3,sh}$

Unit

$\Omega$/m

Formulae

$\frac{m_{z,sh} \rho_{sh}}{2\pi r_{z2,sh}} \operatorname{coth}\left(m_{z,sh} \left(r_{z3,sh}-r_{z2,sh}\right)\right)-\frac{\rho_{sh}}{2\pi r_{z2,sh} \left(r_{z2,sh}+r_{z3,sh}\right)}$

Related

$m_{z,sh}$

Parameter m of sheath

$\pi$

Archimedes' constant $\pi$

$r_{z2,sh}$

Radius of sheath (inner) [m]

$r_{z3,sh}$

Radius of sheath (outer) [m]

$\rho_{sh}$

Specific electrical resistivity of sheath material [$\Omega$.m]

Used in

$\mathscr{z}_3$

Impedance of shield inner surface [$\Omega$/m]

$\mathscr{z}_4$

Mutual impedance of shield [$\Omega$/m]

$\mathscr{z}_5$

Impedance of shield outer surface [$\Omega$/m]