ADSS optical cables work in a large-span two-point support (usually hundreds of meters, or even more than 1 km) overhead state, completely different from the traditional concept of overhead (post and telecommunications standard overhead hanging wire hook program, an average of 0.4 meters for the optical cable 1 Fulcrum). Therefore, the main parameters of ADSS optical cables are in line with the regulations of power overhead lines.
1. Rated tensile strength (UTS/RTS)
Also known as ultimate tensile strength or breaking strength, it refers to the calculated value of the sum of the strength of the load-bearing section (mainly counted as spinning fiber). The actual breaking force should be greater than or equal to 95% of the calculated value (the break of any component in the optical cable is judged to be cable breaking). This parameter is not optional. Many control values are related to it (such as tower strength, tensile hardware, anti-vibration measures, etc.). For fiber optic cable professionals, if the ratio of RTS/MAT (equivalent to the safety factor K of overhead lines) is not appropriate, that is, if a lot of spun fibers are used and the available fiber strain range is very narrow, the economic/technical performance ratio is very poor. Therefore, the author recommends that industry insiders pay attention to this parameter. Generally, MAT is approximately equivalent to 40% RTS.
2. Maximum allowable tension (MAT/MOTS)
Refers to the tension on the optical cable when the total load is calculated theoretically under the design weather conditions. Under this tension, the fiber strain should be ≤0.05% (stranded) and ≤0.1% (central tube) without additional attenuation. In layman’s terms, the excess length of the optical fiber has just been eaten up at this control value. According to this parameter, meteorological conditions and the controlled sag, the allowable span of the optical cable can be calculated under this condition. Therefore, MAT is an important basis for the calculation of sag-tension-span, and it is also an important evidence for characterizing the stress-strain characteristics of ADSS optical cables.
3. Annual average stress (EDS)
Sometimes called daily average stress, it refers to the theoretically calculated tension of the optical cable under load under no wind, no ice and annual average temperature. It can be considered as the average tension (strain) of the ADSS during long-term operation. EDS is generally (16~25)%RTS. Under this tension, the optical fiber should have no strain and no additional attenuation, that is, very stable. EDS is the fatigue aging parameter of the optical cable at the same time, according to this parameter determines the anti-vibration design of the optical cable.
4. Ultimate operating tension (UES)
Also known as special use tension, it refers to the maximum tension of the optical cable that may exceed the design load during the effective life of the optical cable. It means that the optical cable allows short-term overload, and the optical fiber can withstand strain within a limited allowable range. Generally, the UES should be greater than 60% RTS. Under this tension, if the strain of the fiber is less than 0.5% (central tube) and less than 0.35% (stranded), additional attenuation of the fiber will occur, but after the tension is released, the fiber should return to normal. This parameter guarantees the reliable operation of the ADSS optical cable during its lifetime.