Calculation of proximity losses in multistranded conductor bunches

Proximity losses appear in multi-stranded conductors carrying time-varying currents, because each strand is affected by the collective transverse magnetic field of all the other strands. The total proximity loss increases as the square of the number of strands, and, even for small numbers, exceeds that due to skin effect. Total proximity loss is greatest in bunches having circular envelope sections. In bunches having other sections, the losses are reduced, relative to a circular bunch with the same number of strands, by a margin that increases as the bunch shape departs from the circle.