# Mean distance between the phases

This is the geometric mean distance between phases.

In case of three single-core cables in flat formation, equal distance, with regular transposition, this becomes the equation $2 \sqrt[3]{2}\cdot s_{c}$ as it is used in IEC 60287-1-1, chapter 2.3.2.

Symbol
$a_m$
Unit
mm
Formulae
 $L_{earth}$ single-phase system $s_c$ two-phase system $\left(a_{12} a_{23} a_{31}\right)^{\frac{1}{3}}$ three-phase system
Related
$a_{12}$
$a_{23}$
$a_{31}$
$L_{earth}$
$s_c$
Used in
$L_1$
$L_2$
$L_3$
$X_{ar}$
$X_c$
$X_{S1}$
Reactance section 1 [$\Omega$/m]
$X_{S2}$
Reactance section 2 [$\Omega$/m]
$X_{S3}$
Reactance section 3 [$\Omega$/m]