Sheath losses correction factor for cross‐bonded cable systems with unknown minor section lengths: Analytical expressions.

The IEC Standard 60287‐1‐1 contains the formulae for the calculation of the sheath and armour loss factors of a three‐phase cable circuit where sheath circulating current losses are computed for single‐, multiple‐ or cross‐bonded systems. For cross‐bonded systems, the standard gives a formula allowing calculation of the circulating current losses when the lengths of the minor sections are known. When the lengths of the minor sections are not known, the standard suggests using a correction factor of 0.004, which multiplies the circulating current loss factor computed for a multi‐point bonded system. Previous studies by the authors have shown that this assumption may lead to a significant error in the evaluation of the sheath loss factor for some combinations of the minor section lengths. This paper provides analytical formulae for the correction factor in the cross‐bonded system with unknown section lengths with the aim of improving the accuracy of the IEC 60287‐1‐1. Several numerical examples illustrate the applicability and accuracy of the proposed approach. [ABSTRACT FROM AUTHOR]