Proximity effect factor of conductors

The formulae are accurate providing xp does not exceed 2,8, and therefore applies to the majority of practical cases.

Symbol
$y_{p}$
Formulae
$0$one single-core cable
$\frac{2.9 d_{c}^{2} x_{p}^{4}}{s_{c}^{2} \left(0.8 x_{p}^{4} + 192\right)}$two-core cables and two single-core cables
$\frac{2.9 d_{x}^{2} x_{p}^{4}}{s_{c}^{2} \left(0.8 x_{p}^{4} + 192\right)}$two-core cables with sector-shaped conductors
$\frac{d_{c}^{2} x_{p}^{4} \left(\frac{0.312 d_{c}^{2}}{s_{c}^{2}} + \frac{1.18}{\frac{x_{p}^{4}}{0.8 x_{p}^{4} + 192} + 0.27}\right)}{s_{c}^{2} \left(0.8 x_{p}^{4} + 192\right)}$three-core cables and three single-core cables
$\frac{0.666666666666667 d_{x}^{2} x_{p}^{4} \left(\frac{0.312 d_{x}^{2}}{s_{c}^{2}} + \frac{1.18}{\frac{x_{p}^{4}}{0.8 x_{p}^{4} + 192} + 0.27}\right)}{s_{c}^{2} \left(0.8 x_{p}^{4} + 192\right)}$three-core cables with sector-shaped conductors
Used in
$R_{c}$