All-medium self-supporting optical cable (adss) is a kind of non-metallic optical cable composed of all medium materials, including the necessary support system itself, can be directly suspended on the power tower, with no metal, tension resistance, self-supporting, high insulation, no induction, thin diameter, light, easy construction and economic characteristics. It is mainly used for the communication route of overhead high-voltage transmission system, and also can be used for the communication line in the lightning prone area, large span and other overhead laying environment.
Because the ADSS cable is the same dance with the high voltage power line, so its surface in addition to the requirements of ordinary cable anti-ultraviolet radiation, but also required to withstand the test of high voltage and strong electric environment for a long time. The capacitive coupling between the cable and the high voltage phase line and the earth will produce different spatial potentials on the cable surface. Under the action of meteorological environment such as rain, snow and frost and dirt, the potential difference in the wet dirty cable surface local leakage current, the thermal effect makes the cable surface part of the water is evaporated, in the moment of evaporation, leakage current interruption resulting in arc and large heat energy, the accumulation of heat energy will burn the cable surface, forming a dendritic trace, this is the electric mark. Over time, the outer protective layer is damaged by aging, from the surface to the inside, the aging mechanical properties of aramid yarn are reduced, and eventually the cable will be broken. There are two main ways to solve this problem. One is the use of special electric mark resistant sheath material to extrude the outer sheath of arnylon yarn, that is, the use of AT electric mark resistant sheath to reduce the electric mark corrosion on the cable surface of strong electricity; In addition, professional software is used to calculate the spatial potential distribution on the power tower and draw the electric field intensity distribution diagram, according to this scientific basis to determine the specific suspension point of the cable on the tower, so as to avoid the cable by stronger electric field.