Sheath Loss Factors Taking Into Account the Proximity Effect for a Cable Line in a Touching Flat Formation

This paper presents the development of a correction coefficient for the International Electrotechnical Commission (IEC) Standard 60287-1-1 formula for the sheath loss factor of the middle cable in a touching flat formation. The solid sheaths are bonded and earthed at both ends of an electrical section. The reason for this correction is to take into account a nonuniform distribution of the losses within each sheath arising from the proximity effect. The coefficient is developed by using the filament method as well as the stochastic optimization algorithm based on differential evolution. The IEC formulae for the sheath loss factors of the outer cables, forming a part of the touching formation, do not need to be modified in order to consider the proximity effect.