Mathematical model of dry-band arcing on self-supporting, all-dielectric, optical cables strung on overhead power lines

The service history of self-supporting, metal-free, optical cables strung on power transmission lines is briefly reviewed; they can suffer from dry-band arcing damage. By using the results of experimental measurements on low-current arcs, an analysis is presented of dry-band arcing, which establishes the conditions necessary for stable arcing. It is shown that the electrical potential difference available for dry-band arcing and the resistance of wet pollution, which both influence the magnitude of the earth-leakage current flowing to ground from a wet cable, are important parameters in determining the threat of damage. The way in which this threat varies with line type, mounting position, phasing arrangement and geographical location is explained. There exists a threshold combination of induced voltage and wet pollution resistance, below which stable dry-band arcing will not occur