Positive sequence impedance

These equations are based on the Cigré Guide 531 for symmetric systems without earth return path.

For subsea armoured three-core cables, the three screens are assumed to be solidly bonded to the armour at least at both ends.

$R_c+1j X_c$single point or cross-bonding, and multi-core cables with common screen
$R_c+1j X_c+\frac{{X_s}^2}{R_s+1j X_s}$bonded at both sides
$R_c \left(1+\lambda_2\right)+1j X_c+\frac{{X_s}^2}{R_s+1j X_s}$armoured three-core cables bonded at both sides