ADSS optical fiber cable works in an overhead state supported by two points with a large span (usually hundreds of meters, or even more than 1 km), which is completely different from the traditional concept of “overhead” (post and telecommunications standard overhead hanging wire hook program, an average of 0.4 meters has no effect on optical cables). 1 pivot). Therefore, the main parameters of ADSS optical cables are in line with the regulations of power overhead lines.
1. Tension (MAT/MOTS) is allowed.
Refers to the tension of the optical cable when the total load is theoretically calculated under the design meteorological conditions. Under this tension, the fiber strain should be ≤0.05% (layer twist) and ≤0.1% (center tube) with no additional attenuation. In layman’s terms, that is, the excess length of the optical fiber is just “eaten” at this control value. According to this parameter and meteorological conditions and the controlled sag, the allowable use span of the optical cable under this condition can be calculated. Therefore, MAT is an important basis for the calculation of sag-tension-span, and it is also an important evidence to characterize the stress-strain characteristics of ADSS optical cables.
2. Rated tensile strength (UTS/RTS).
Also known as ultimate tensile strength or breaking force, it refers to the calculated value of the sum of the strengths of the bearing cross-section (mainly textile fibers). The actual breaking force should be ≥95% of the calculated value (the breakage of any element in the optical cable is judged as cable breakage). This parameter is not optional, and many control values are related to it (such as the strength of the tower, tensile fittings, anti-vibration measures, etc.). For optical cable professionals, if the ratio of RTS/MAT (equivalent to the safety factor K of overhead lines) is not appropriate, even if a lot of fiber is used, and the available optical fiber strain range is very narrow, the economic/technical performance ratio is very poor. Therefore, the author recommends that people in the industry pay attention to this parameter. Typically, MAT is approximately equivalent to 40% RTS.
3. Annual mean stress (EDS).
Sometimes referred to as the daily average stress, it refers to the tension of the cable under the load of theoretical calculation under the condition of no wind, no ice and annual average temperature, which can be regarded as the average tension (strain) of the ADSS during long-term operation. EDS is generally (16~25)%RTS. Under this tension, the fiber should be strain-free, without additional attenuation, i.e. very stable. EDS is also the fatigue aging parameter of the optical cable, and the anti-vibration design of the optical cable is determined according to this parameter.
4. Ultimate Running Tension (UES).
Also known as special use tension, it refers to the tension that the cable is subjected to when the load exceeds the design load during the effective life of the optical cable. It means that the optical cable is allowed to be overloaded for a short time, and the optical fiber can withstand strain within a limited allowable range. Usually, the UES should be > 60% RTS. Under this tension, the fiber strain is less than 0.5% (center tube) and <0.35% (layer twist), the fiber will have additional attenuation, but after the tension is released, the fiber should return to normal. This parameter ensures the safe operation of the ADSS cable during its lifetime.
Post time: Nov-25-2022