Cableizer ®

Positive sequence impedance

Definition according to CIGRE TB 531 chap. 4.2.4.3

Definition for three-core cables with armour was specifically for submarine armoured three-core cables, with individual separate metal screens.

For cables, the negative sequence impedance is equal to the positive sequence impedance.

Symbol
$Z_{d}$
Unit
$\Omega$/m
Formulas
$Z_{a}-Z_{x}-\frac{\left(Z_{m}-Z_{x}\right)^2}{Z_{s}-Z_{x}}$single-core cables, both-side bonding
$Z_{a}-Z_{x}$single-core cables, single-point bonding
$Z_{a}-Z_{x}$single-core cables, cross-bonding
$Z_{a}-Z_{x}-\frac{\left(Z_{m}-Z_{x}\right)^2}{Z_{s}-Z_{x}}+R_{c} \lambda_{2}$three-core cables, with armour
$R_{cDC} \left(1+y_{p}+y_{s}+\lambda_{1}+\lambda_{2}+\lambda_{3}\right)+j X_{d}$pipe-type cables
Related
$\lambda_{1}$
Loss factor shield (screen/sheath)
$\lambda_{2}$
Loss factor armour
$\lambda_{3}$
Loss factor steel pipe pipe-type cable
$R_{c}$
Electrical resistance conductor [$\Omega$/m]
$R_{cDC}$
Electrical resistance DC conductor [$\Omega$/m]
$X_{d}$
Reactance steel pipe [$\Omega$/m]
$y_{p}$
Proximity effect factor conductor
$y_{s}$
Skin effect factor conductor
$Z_{1}$
Positive sequence impedance [$\Omega$/m]
$Z_{a}$
Self impedance of phase conductor with earth return [$\Omega$/m]
$Z_{m}$
Mutual impedance between phase conductor and metal screen with earth return [$\Omega$/m]
$Z_{s}$
Self impedance of metal screen with earth return [$\Omega$/m]
$Z_{x}$
Equivalent mutual impedance between cables with earth return [$\Omega$/m]