Factor $F_e$ for eddy-current losses

Single core cables with Milliken conductors and solid bonding:
Where the conductors are subject to a reduced proximity effect, as with Milliken conductors, the eddy-current loss factor cannot be ignored, but shall be optained by multiplying the value of the eddy-current loss factor for single-core cables bonded at single point for the same cable configuration by the factor $F_e$.

Two- and three-core cables with steel tape armour:
The addition of steel tape armour increases the eddy-current loss in the sheath. The values for the eddy-current loss factor shall be multiplied by the factor $F_e$ if the cable has steel-tape armour.

Symbol
$F_e$
Formulae
$\frac{4{M_e}^2 {N_e}^2+\left(M_e+N_e\right)^2}{4\left({M_e}^2+1\right) \left({N_e}^2+1\right)}$$n_c<=1$
$\left(1+\frac{\left(\frac{d_s}{d_{ar}}\right)^2}{1+\frac{d_{ar}}{\mu_s \delta_{ar}}}\right)^2$$n_c>1$