All-dielectric self-supporting (ADSS) cable is a type of optical fiber cable that is strong enough to support itself between structures without using conductive metal elements. It is used by electrical utility companies as a communications medium, installed along existing overhead transmission lines and often sharing the same support structures as the electrical conductors.
In the world of telecommunications, the use of All-Dielectric Self-Supporting (ADSS) cables has become increasingly popular due to their versatility and durability. However, designing and producing the right ADSS cable can be a complex and challenging process.
The most important Construction designIn order to properly design the structure of the ADSS cable, many aspects must be considered. Including mechanical strength, conductor sag, A wind speed b ice thickness c temperature d topography, Span, Voltage.
Usually, when you are in production, you need to consider the following questions.
Jacket Type: AT/PE
PE sheath: ordinary polyethylene sheath. For power lines below 110KV, and ≤12KV electric field strength. The cable should be suspended at a position where the electric field strength is small.
AT sheath: anti-tracking sheath. For power lines above 110KV, ≤20KV electric field strength. The cable should be suspended at a position where the electric field strength is small.
Out Cable Dia.: Single Jacket 8mm-12mm;Double jacket 12.5mm-18mm
Fiber Count: 4-144Fibers
Aramid Yarn Details: Something like (20*K49 3000D)This main calculation of tensile strength.
According to the stress formula, S=Nmax/E*ε,
E (Tensile modulus)=112.4 GPa（K49 1140Dinner）
ε=0.8%
Usually designed strain<1%（Stranded Tube）UTS;
≤0.8%，evaluation
Nmax=W*(L2/8f+f);
L=span(m);usually 100m,150m,200m,300m,500m,600m;
f=Cable sag；usually 12m or 16m.
Nmax=W*(L2/8f+f)=0.7*（500*500/8*12+12）=1.83KN
S=Nmax/E*ε=1.83/114*0.008=2 mm²
Saramid(K49 2840D)=3160*10-4/1.45=0.2179mm²
N numbers aramid yarn=S/s=2/0.2179=9.2
General aramid fiber hinge pitch is 550mm-650mm,angle=10-12°
W=Maximum load (kg/m)=W1+W2+W3=0.2+0+0.5=0.7kg/m
W1=0.15kg/m(This is the weight of ADSS cable)
W2=ρ*[(D+2d)²-D²]*0.7854/1000(kg/m) (This is the weight of ICE)
ρ=0.9g/cm³,the density of ice.
D=Diameter of ADSS. Usually 8mm-18mm
d=Ice cover thickness;No ice=0mm,Light ice=5mm,10mm;Heavy ice=15mm,20mm,30mm;
Let’s say the ice is thick is 0mm,W2=0
W3=Wx=α*Wp*D*L=α*（V²/1600）*(D+2d)*L/9.8 (kg/m)
Let’s say the wind speed is 25m/s, α=0.85; D=15mm;W3=0.5kg/m
Wp=V²/1600 （Standard partial pressure formula，V means wind speed）
α= 1.0(v＜20m/s);0.85(20-29m/s);0.75(30-34m/s);0.7(＞35m/s) ;
α means Coefficient of unevenness of wind pressure.
Level | phenomenon | m/s
1 Smoke can indicate the wind direction. 0.3 to 1.5
2 The human face feels windy and the leaves move slightly. 1.6 to 3.3
3 The leaves and micro-techniques are shaking and the flag is unfolding. 3.4~5.4
4 The floor dust and paper can be blown up, and the twigs of the tree are shaken. 5.5 to 7.9
5 The leafy small tree sways, and there are wavelets in the inland waters. 8.0 to 10.7
6 The big branches are shaking, the wires are vocal, and it is difficult to lift the umbrella. 10.8~13.8
7 The whole tree is shaken, and it is inconvenient to walk in the wind. 13.9~17. l
8 The micro-branch is broken, and people feel very resistant to moving forward. 17.2~20.7
9 The grass house was damaged and the branches were broken. 20.8 to 24.4
10 Trees can be blown down, and general buildings are destroyed. 24.5 to 28.4
11 Rare on land, large trees can be blown down, and general buildings are severely damaged. 28.5~32.6
12 There are few on the land, and its destructive power is enormous. 32.7~36.9
RTS: Rated tensile strength
Refers to the calculated value of the strength of the bearing section (mainly counting the spinning fiber).
UTS: Ultimate Tensile Strength UES>60% RTS
In the effective life of the cable, it is possible to exceed the design load when the cable by the maximum tension.That means the cable can be overloaded for a short time
MAT: Max allowable working tension 40% RTS
MAT is an important basis for sag – tension – span calculation, and also an important evidence to characterize the stress-strain characteristics of ADSS optical cable.Refers to the design of meteorological conditions under the theoretical calculation of the total load, cable tension.
Under this tension, the fiber strain should be no more than 0.05% (laminated) and no more than 0.1% (central pipe) without additional attenuation.
EDS: Every Day Strength 16~25）% RTS
The annual average stress is sometimes called the daily average stress, refers to the wind and no ice and the annual average temperature, the theoretical calculation of the load cable tension, can be considered as the ADSS in the long-term operation of the average tension (should) force.
EDS is generally (16~25) % RTS.
Under this tension, the fiber should have no strain, no additional attenuation, that is, very stable.
EDS is also the fatigue aging parameter of optical fiber optic cable, according to which the anti-vibration design of optical fiber optic cable is determined.
In summary, designing and producing the right ADSS cable requires a thorough understanding of the project requirements, the selection of high-quality materials, and the implementation of robust quality control measures. With these considerations in mind, telecommunications providers can confidently deploy ADSS cables that meet the demands of today’s connectivity needs.
original source: https://www.gl-fiber.com/news/how-to-design-and-produce-right-adss-cable/
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