Loss factor of shield by eddy currents

This is the loss factor for sheath caused by eddy currents.

For cables with sheaths bonded at both ends (solid bonding) of an electrical section, the loss due to eddy currents can be neglected.

Where the conductors are subject to a reduced proximity effect, as with Milliken conductors, the sheath loss factor $\lambda_{12}$ for eddy current losses cannot be ignored, but shall be obtained by multiplying the value of $\lambda_{12}$, obtained for cables with single-point bonding for the same configuration, by the factor $F_e$.

Acc. to IEC 60287-1-1, clause 2.3.6.1, the eddy-current losses for wire screen and an equalizing tape, or foil screen over the wires are considered negligible for single-core cables. The standard does not specify if this is only applicable for round wires or also flat wires, we consider it only applicable for round wires. We also allow any cable with round wires (including multicore cables) to consider the eddy-current nevertheless upon choice.

Symbol
$\lambda_{12}$
Formulae
$\frac{R_e}{R_c} \left(g_s \lambda_0 \left(1+\Delta_1+\Delta_2\right)+{10}^{12}\frac{\left(\beta_1 t_{sh}\right)^4}{12}\right)$Single-core cables
$\frac{16{\omega}^2{\cdot}{10}^{-14}}{R_c R_e} \left(\frac{s_c}{2d_e}\right)^2 \left(1+\left(\frac{s_c}{2d_e}\right)^2\right)$Two-core cables with round conductors
$\frac{10.8{\omega}^2{\cdot}{10}^{-16}}{R_c R_e} \left(\frac{0.74d_c+t_{2i}}{d_e}\right)^2 \left(12.2+\left(\frac{0.74d_c+t_{2i}}{d_e}\right)^2\right)$Two-core cables with sector-shaped conductors
$\frac{3R_e}{R_c} \left(\frac{\left(\frac{2s_c}{\sqrt{3} d_e}\right)^2}{1+\left({10}^7\frac{R_e}{\omega}\right)^2}+\frac{\left(\frac{2s_c}{\sqrt{3} d_e}\right)^4}{1+4\left({10}^7\frac{R_e}{\omega}\right)^2}\right)$Three-core cables with round conductors, $R_{sh}$ <= 100$\mu \Omega$/m
${10}^{-14}\frac{3.2{\omega}^2}{R_c R_e} \left(\frac{2s_c}{\sqrt{3} d_e}\right)^2$Three-core cables with round conductors, $R_{sh}$ > 100$\mu \Omega$/m
$\frac{\frac{0.94R_e}{R_c} \left(\frac{d_c+t_{2i}}{d_e}\right)^2}{1+\left({10}^7\frac{R_e}{\omega}\right)^2}$Three-core cables with sector-shaped conductors
$F_{ar} \lambda_{12}$cables with steel tape (and wire) armour
$0$cables with each core in separate sheath (SL type) and pipe-type cables
$F_e \lambda_{12}$cables with milliken conductors, when bonded on both sides