Cableizer ®

Mean diameter armour

The equation for duplex/triplex and pipe-type cables is according to CIGRE TB 880 Guidance Point 41.

Symbol
$d_{ar}$
Unit
mm
Formulas
$\frac{S_{ar}}{\pi}$multi-core cables without filler (duplex/triplex), pipe-type cables
$D_{ab}+n_{a,1} t_{a,1}$steel tape armour
$D_{ab}+t_{a,1}+t_{a,2}$otherwise
Related
$D_{ab}$
Diameter over armour bedding [mm]
$n_{a,1}$
Number of wires armour 1
$\pi$
Archimedes' constant $\pi$
$S_{ar}$
Circumference armour [mm]
$t_{a,1}$
Thickness armour 1 [mm]
$t_{a,2}$
Thickness armour 2 [mm]
Used in
$A_{ar}$
Cross-sectional area armour [mm$^2$]
$d_e$
Equivalent diameter of screen/sheath and armour [mm]
$\delta_{ar}$
Equivalent thickness of armour [mm]
$F_{ar}$
Factor $F$ armour losses
$F_{lay,ar}$
Effective length per unit lay length armour
$GMD$
Geometric mean distance between phases of the same system [m]
$H_1$
Inductance $H_1$ armour [H/m]
$H_2$
Inductance $H_2$ armour [H/m]
$H_3$
Inductance $H_3$ armour [H/m]
$\lambda_2$
Loss factor armour
$\lambda_{21}$
Loss factor armour, circulating currents
$\lambda_{22}$
Loss factor shield, eddy currents
$\phi_{ar}$
Angle between armour and cable axis [rad]
$X_{ar}$
Self reactance armour [$\Omega$/m]
Image

CIGRE TB 880 Guidance Point 41