A mitigation method for dry-band arcing caused deterioration of ADSS fiberoptic cables

Electric utilities install ADSS (all dielectric self supporting) fiber-optic cables on high voltage transmission lines. When the cables are polluted and wetted by rain or salt water from the sea, a conductive layer is formed on the cable. The capacitive coupling between the high voltage conductors and the fiber-optic cable causes a current in the layer leading to dry-band arcing. It is believed that dry-band arcing causes various ADSS cable failures around the globe. This paper proposes a technique to mitigate damage caused by dry-band arcing on the ADSS cable jacket. A grounded armor rod assembly supports the fiber optic cables at the towers. It is suggested that suspending the armor rod assembly on a composite nonceramic insulator will eliminate dry-band arcing on the fiber-optic cables. To validate this method, a set of laboratory experiments was performed using different insulators and pollution levels. The experimental results indicate that the use of a 69 kV silicone insulator eliminates dry-band arcing on fiber-optic cables below 20 kV open circuit voltage even under heavy pollution conditions. A 115 kV insulator is effective up to 60 kV open circuit voltage. The proposed technique is economical. Installing insulators only in critical areas, typically near seacoasts, can further reduce the cost.