When a non-magnetic armour is present, $d$ is replaced by $d_e$ in the following formulas.

Symbol
$\Delta _{\mathrm{2}}$
Unit
-
Formulae
$0$trefoil arrangement and non-flat formations
$21 m_{\mathrm{0}}^{3.3} \left(\frac{d_{\mathrm{s}}}{2 s_{\mathrm{c}}}\right)^{1.47 m_{\mathrm{0}} + 5.06}$flat formation, outer cable leading phase
$0$flat formation, center cable phase
$0.92 m_{\mathrm{0}}^{3.7} \left(\frac{d_{\mathrm{s}}}{2 s_{\mathrm{c}}}\right)^{m_{\mathrm{0}} + 2}$flat formation, outer cable lagging phase
Related
$d_{\mathrm{e}}$
$d_{\mathrm{s}}$
Used in
$\lambda_{\mathrm{1es}}$