Parametric Study of Losses in Cross-Bonded Cables: Conductors Transposed Versus Conductors Nontransposed

Conductor transposition, for cross-bonded cables, is recommended in the ANSI/IEEE Standard 575-1988 as a means to reduce interference with communication systems. In this paper, it is shown that reduced interference comes at the price of increased cable losses, which is an issue not addressed in the 1998 edition of the IEEE Standard 575. Analytical formulas are obtained for the calculation of the positive-sequence resistance for transposed and not transposed conductors to shed light on the reasons why the losses increase when the conductors are transposed. It has been found that for cross-bonded cables installed in flat formations, the positive-sequence resistance of transposed conductors is always larger than that of nontransposed conductors. Parametric studies are performed by varying all of the construction and installation parameters that affect the value of the positive-sequence resistance. In particular, we have changed the separation distance between cables, the insulation thickness, the number and resistance of the concentric wires, and the resistivity of the soil among other parameters. Examples on transmission and distribution cables are discussed.