INFLUENCE OF THE AMBIENT TEMPERATURE ON THE MECHANICAL TENSION OF THE OPTICAL CABLE

Abstract

To ensure the quality and reliability of the fiber-optic communication line during the exploitation, it is necessary to constantly monitor the technical condition of the optical cable (OC), first of all, the tension in the fiber. Mechanical tensions in the optical fiber due to macro- and microbends lead to a change the signal’s attenuation coefficient. Therefore, the study of the effect of the temperature of the operating environment of the optical cable on its mechanical tensions is relevant. The purpose of the work is to determine the mechanical stress of the dielectric optical cable as a function of the temperature change (tx) at constant values of the tension in the cable, which correspond to the corresponding elongation of the cable (εр). The article investigates the effect of ambient temperature on the mechanical tensions in the cable (σ0x). Conducted on the example of a cable type OKL-3-D1 of the domestic manufacturer "Odeskabel" with a dielectric central power element made of fiberglass of the "Polystal" type, and a peripheral power element – made of aramid threads "Twaron 2200-1055". An estimate of the mechanical tension in this OC was obtained at different temperature values from -40 °C to 60 °C and at different elongations. For this purpose, the values of the temperature coefficient of linear expansion, Young’s modulus of such a cable were obtained in the work. In the studies, the values of constant tensile loads of the cable, which correspond to its elongation from 0.2 % to 0.6 %, were used. According to the results of the study, at a constant mechanical load of a given type of cable, which corresponds to its certain elongation εр = 0.6 %, a decrease in mechanical tensions up to 7 % was obtained. Due to the fact that the mechanical stress in the optical cable consists of two parts, the first of which depends on the mechanical loads, and the second depends on the temperature change of the cable's operating environment. According to the work [2], the first component is much larger than the second, but its changes, established in this work, in critical situations for fiber-optic communication lines are of significant importance, which must be taken into account during the design and operation of lines. In general, the study of σ0x made it possible to establish that the mechanical stresses of the OC de crease with temperature increase due to the negative temperature coefficient of linear expansion of the aramid threads.