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Any conductor p, lying parallel with a set of three conductors carrying balanced three-phase currents, will have a voltage gradient $E_p$ induced along its length.
Clearly, as the spacing of the parallel conductors increases in relation to the mutual spacing of the groups of cables, the induced voltage tends to zero. Similarly, if the three cables of the group are regularly transposed at even intervals, the induced voltages in the parallel conductor sum to zero over a complete cycle of transposition.
| $+j \omega I_{kb} 2{\cdot}{10}^{-7} \left(\frac{1}{2} \ln\left(\frac{S_{ap} S_{cp}}{{S_{bp}}^2}\right)+j \frac{\sqrt{3}}{2} \ln\left(\frac{S_{cp}}{S_{ap}}\right)\right)$ | IEEE 575-2014 |
| $-j \omega 2{\cdot}{10}^{-7} \left(I_{ka} \ln\left(\frac{S_{ap}}{r_g}\right)+I_{kb} \ln\left(\frac{S_{bp}}{r_g}\right)+I_{kc} \ln\left(\frac{S_{cp}}{r_g}\right)\right)$ | Energies 2022, 15-05010 |