Substitution coefficient $\Delta_1$ for eddy-currents

Symbol
$\Delta _{1}$
Formulae
$\left(\frac{d_{e}}{2 s_{c}}\right)^{0.92 m_{0} + 1.66} \left(1.14 m_{0}^{2.45} + 0.33\right)$trefoil arrangement and non-flat formations
$4.7 m_{0}^{0.7} \left(\frac{d_{e}}{2 s_{c}}\right)^{0.16 m_{0} + 2}$flat formation, other outer phase (leading 3/T/W)
$0.86 m_{0}^{3.08} \left(\frac{d_{e}}{2 s_{c}}\right)^{1.4 m_{0} + 0.7}$flat formation, middle phase (1/R/U)
$- \frac{\sqrt{m_{0}} \left(\frac{d_{e}}{2 s_{c}}\right)^{m_{0} + 1} \left(0.74 m_{0} + 1.48\right)}{\left(m_{0} - 0.3\right)^{2} + 2}$flat formation, outer phase with greater loss (lagging 2/S/V)