Induced currents on optical fibre cables installed in high voltage transmission line environments

Specialized fibre optic cables may be installed by suspending the cables from transmission line towers such that they are situated under the high voltage conductors in an outdoor environment. Long term accumulation of wind-borne pollutants followed by periods of wetting may result in leakage currents flowing axially along the optical fibre cables. Under certain severe conditions, small arcs may form on the surface of the cable. The objective of this paper is to present two simulation processes that may be used to determine these leakage currents and compare the predicted values with experimentally determined values. The effects of system voltage, attachment point of the cable at the tower and span length on the magnitude of the leakage currents have all been investigated. The feasibility of using these models to predict dry-band arcing on these cables was also determined.