Reasons for the aging of adss optical cable

Use of ADSS Fiber Optic Cable - All Dielectric Self Supporting Fiber Optic Cable is widely used all over the world. Extensive improvements since implementation are in the "arc resistant" sheath. Jacket materials improve the performance of fiber optic cables and extend their life. However, even when some degree of risk can be defined, it is impossible to predict the life expectancy of fiber optic cables in any given environment. In addition, there are risks associated with some of the large volumes of fiber optic cables already installed, but such issues are often not reported due to commercial sensitivities

The current flow along the ADSS cable acts as an aging factor for the jacket material. These currents along the cable are expected due to potential gradients from 3 sources: through the conductor, the capacitive coupling between the ADSS cable and ground; through the voltage difference between the clamp and the midspan location; and through the conduction of the cable surface sex.

Typically, the midspan has a large potential, where the ADSS cable is positioned higher than the conductor (cable sags), and the ground potential is forced by the wire and the grounded metal clamp of the ADSS cable. was razed to the ground. Conductivity is affected by cable contamination and humidity.

As the sheath material ages, it becomes hydrophilic and its resistance per unit length can drop to very low values of only a few hundred kiloohm/meter and current rise to a few milliamps. For a 150kV laboratory measurement line, the results show that the polyethylene limits are 1 mA and 1.5 mA.

Surface currents and discharges can cause Joule heating of moisture and an increase in the surface temperature of the cable. After this heating effect, dry banding may thus occur on the surface of the cable. Dry banding can occur near towers where currents are typically high. The dry tape has a higher linear impedance than the rest of the cable surface.

This high impedance characteristic results in large voltage drops during dry cable shorts and arcing. When the current is high enough to sustain the arc, an erratic discharge occurs across the dry strip. The uneven conductivity on the cable surface caused by the dry tape increases the localized electric field and causes corona and arcing that generate ultraviolet light and ozone, both of which can damage the cable surface.

ADSS fiber optic cable works well if located in a temperate and benign location. Aging of the polyethylene sheath material is identified by loss of its "shiny" aspect, and exhibits only low levels of aging, manifested by relatively low hydrophobicity. The conclusion is that this ADSS fiber optic cable meets its design specifications, is installed in place on the tower, and its jacket is not even close to end of life.

The above is the reason for the aging of adss optical cable.