Substitution coefficient $\Delta_2$ for eddy-currents

Symbol
$\Delta _{2}$
Formulae
$0$trefoil arrangement and non-flat formations
$21 m_{0}^{3.3} \left(\frac{d_{e}}{2 s_{c}}\right)^{1.47 m_{0} + 5.06}$flat formation, other outer phase (leading 3/T/W)
$0$flat formation, middle phase (1/R/U)
$0.92 m_{0}^{3.7} \left(\frac{d_{e}}{2 s_{c}}\right)^{m_{0} + 2}$flat formation, outer phase with greater loss (lagging 2/S/V)