Discussion on Design and Construction of ADSS cable issues

Abstract: In this article, According to the cable and fiber FAQs performance in the construction process, and discuss the relationship between the structure and design of their ADSS cable. Describe the differences between ADSS cable design, for different regions and different construction conditions, under different circumstances. And make the brief analysis for some common faults.

Introduction

ADSS all dielectric self-supporting fiber optic cable with its light weight , interference, lightning , etc. , have been widely used in China ´s electric power communication for China´s power communication carries half. As China’s vast land, north and south, mountains, terrain, very complex, especially in parts of the mountains, rocks phosphorus column construction environment is poor. And because of the structure and use characteristics ADSS cable, its construction methods and requirements significantly different from ordinary cable. If the structural design and construction by conventional methods, can easily lead to an unexpected failure, currently widespread in the industry due to improper construction or design defects, resulting in unexpected failures after construction of the cable, it may result in broken fiber or high attenuation point, manufacturers opinions vary and engineering teams, unclear responsibilities, similar to these cases, manufacturers are taking responsibility for a scapegoat. Therefore, work together to strengthen research in this area, to avoid failure in engineering construction, is very important. The following are some of the research and study we conducted in structural improvements and construction methods, to find some rules and measures for peer reference.

1, The cable structure and process methods
We all know that the design of the cable structure directly related to the use of performance fiber optic cable construction costs and reasonable structure design, will bring two benefits. Performance indicators and to achieve the best cost structure optimization is our common goal.
ADSS cable structure is usually divided into two layer stranded tube and the center beam and cutter style ones, the structure shown in Figure A:


We can see from the figure, Stranded ADSS is characterized by having a central strength member FRP, it is mainly the central supporting role, and some people call it the center of anti-fold rod, beam tube is not. For the determination of the size of the center FRP, relatively speaking, is slightly a little better, but considering the cost factor, not the bigger the better, here have a degree. For the usual layer twisted structure, generally are used a +6 structure, the cable cores in the case of not too much, there are a structure using a +5. Theoretically speaking, if the structure satisfies the cores using a +5 structure, the cost will be a little lower, but the case of the same diameter, the diameter of the multi-center FRP +6 only a 70% point of the structure, make up The cable will be more flexible, cable bending strength is poor, when construction will increase the difficulty. If using a 1 +6 structure, without increasing the cable diameter, the diameter must be reduced, which in turn will give a difficult process because of the cable to ensure that there is more than long enough, is not necessary small diameter Therefore, the value must be moderate. Through the test results of samples of different technological structure of comparative analysis, such as the use φ2.2 tube, 1 +5 structure, and the use of φ2.0 tube, similar to a +6 construction costs, but such a structure +6 , relatively thick FRP center will increase the rigidity of the cable, fiber optic cable performance is more reliable, more security, better round structure. The choice to choose this structure and the number of each tube fiber core, which depends on each level of technology. A large number of cores usually best to employ a large span stranded, this structure can be done over a long relatively bigger, currently the main structure, and the trunk using the most appropriate.

For the central tube ADSS cable, relatively low cost structure, an economic structure, the outer diameter of the cable is relatively small, the weight is light, but also help reduce wind load and ice load. However, due to the lack of anti-folding center bar, cable will seem quite soft, especially when installing fittings, must pay attention to methods of operation, otherwise it will damage the cable. Here to remind you that the production of this central tube ADSS cable, be sure to pay attention to controlling the production process production, one more than long, the second is the cable sheath process. Typically, such a structure in the small or small carrying capacity across conditions is both economical and practical choice. Cable cores can do 48 cores, from fiber to finished product can once completed. Rural power grids are a best choice.


2, The construction method
On ADSS formal construction methods must be adopted to put the line tension method, but some construction units, due to the lack of special construction equipment, the use of artificial traction actinomycetes, construction risk is large, because many people, due to the uneven force, will fiber optic cable under the conditions of constant tension without laying fiber optic cable should force local variables are inconsistent, excess length change is not the same for the cable will bring long-term risks. If it is laying artificial, be sure to pay attention to the force of uniformity. The biggest advantage of mechanical actinomycetes is constant tension, the cable should always be variable within a stable range. And because the tension controllability of different cable specifications, take a different release tension, in order to ensure the quality of construction to meet the design requirements. Figure II is conventional process principle diagram construction equipment.



Which type of tractor wheel traction and reel type two, usually case are used traction wheel type. Requirements of the traction sheave, the minimum outer diameter of the traction sheave should be at least 70 times the cable diameter, and some as large as possible, the grooves of the traction sheave should be recommended as a buffer layer of an elastic rubber to avoid scratching the optical cable. In the course of the discharge line, traction and braking systems should operate smoothly, causing the cable to prevent any sudden pull or impact, these systems should be adjusted at any time and can be stably maintained constant tension and put the line speed, tension machines and put on the line, and limiting device should display the tension, the tension machine and actinomycetes machine in accordance with the requirements of Tension lines and fiber optic cable installed weight and stride to decide on the proper tension machine tugboat brakes, make cable tension can maintain a specific traction in a variety of speed, tension machines and actinomycetes machine should have a flexible body makes when you put the brake line suspended on the cable tension remained unchanged, the best protection is automatic type apparatus.

For the pulley diameter, but also has requirements, usually requires bone wheel diameter is 40 times the cable diameter or more of these. The minimum radius of the pulley groove should not be less than 55% of the cable diameter, the depth of not more than 25% of the cable diameter.

Construction in individual events, we also discovered improper methods and tight line tight line device damaged cable. The purpose is to carry the cable tight line sag and tension adjustment, not because of tight line damaged cable reasons, requiring tight line can withstand the tension of the cable should be greater than the maximum pulling tension.
When installing fittings, also very likely to cause damage to the cable. Therefore, when installing fittings, especially pre-twisted wire-type fittings, must be preformed using special mounting fittings, prohibit the use of similar tools such as a screwdriver. Due to incorrect operation, some will make a place in the Golden fiber breakage or loss appears high point, sometimes resulting in the cable surface roughness, coupled with end fittings, it is likely to cause corrosion of electrical cable. This is a very serious problem and must be caused by construction personnel supervision, supervision of staff´s attention.

Construction of actinomycetes speed control, is also an important parameter, normal conditions decentralization line speed shall not exceed 30 m / min. Must be supervised at each tower.

Because unlike the ordinary cable ADSS cable, cable bending performance is not very good, so the construction process to cut anti-optic cable is folded, folded after the phenomenon typically FRP is broken, loose tube was off injured, with fiber optic OTDR test have high attenuation areas or high attenuation point, as the sheath material toughness characteristics, the jacket surface will not be much of scars. More serious causes FRP puncture and damage the fiber loose tube, fiber cut occurs phenomenon.

These are due to improper construction caused. As owners and cable manufacturers, the construction site must be strengthened supervision and monitoring. In many scene we discovered that many of the construction team, because of the knowledge ADSS cable is not very understanding, lack of construction experience ADSS cable, sometimes to get experience in the construction of the cable laying fiber optic cable; some also lack qualified in this area, East La West Cou several workers, Hoo Nongnong; some equipment is not complete, indigenous methods, the job is not standardized. Which gave the security cable laying risks?

Unreasonable design and irregular operations are the root cause of the anomaly cable construction. As part of our fiber optic cable manufacturers, the first structural design should start laying a different environment, weather conditions, load size, design methods should differ. On the engineering side, as the cable manufacturers, the need to strengthen the supervision of the project, avoid and prevent the occurrence of anomalies.

3, A common phenomenon and prevention of accidents
3.1 exterior damage
As some of the cable line is the result of hilly or mountainous, rocky hills, bushes spine health, the cable is very easy on the rocks or Zashu friction, extremely easy bruising, or being bent, especially cable jacket is worn, the surface is not smooth when using environment due to dust and salt, prone to electrical corrosion, causing great harm to life. Construction must be people care to carefully inspect preparations before pulling.

3.2 fiber and high loss points
Fiber cut and phenomena are due to high loss point in the construction of local stress caused during the discharge line, in the process of laying fiber optic cable jumping round, uneven pace, uneven force constant, corner guide wheel diameter, as well as cable circle phenomenon, can cause sometimes find the center of FRP broken, because the center of FRP is non-metallic materials, fiber optic cables are stretched and then retracted, disconnect the Department will dislocation, decapitation will kill wound FRP fiber loose casing, as well as injury to the fiber, the light causing high loss points, weight fiber cut occurs. This phenomenon is more often the fault occurred many people would think is the quality of the cable, the fact is that the construction caused the accident. Therefore, constant tension control during construction is important, but also uniform.

3.3 Failure fiber cut end

Fiber cut failure Tension side is relatively frequent one accident , often occurs in the strain fittings ( pre-twisted wire ) near distance gold with end within one meter , but also from the tower cited under the gold with the back part of the former is often Because of the pre-twisted wire fittings when artificially caused by improper operation , which is often not convenient because of the terrain traction in the line -side angle too tight or short with the tower ( pole ) occurred special small bending force radius , so that the local cable caused by force . To draw attention to the direction in line with the direction of the cable construction should allow cable linear force.

As the cable jacket material and force elements have good elastic properties are often subjected to force in a short time after the cable sheath surface does not appear visible injuries , while inside the fiber components have been damaged by the force , this is when most people would think that the quality of the cable itself , cause problems judgment errors. I hope to give time to analyze the phenomenon of issues to deal with such a judgment.

Any party to the fiber optic cable construction , the construction side is good , the owner or, cable manufacturers or, do not want an accident to strengthen as long as the construction of prevention, attention to construction methods, attention to every detail , to avoid the occurrence of anomalies . Matching measured pre-construction, construction supervision, everything goes according to procedures and reduce errors.

4 Conclusion
ADSS cable due to its use of the environment and their own characteristics, the market outlook is not optimistic, especially in the use of saline areas, high-field environment, galvanic corrosion is severe, which is its weakness, but in some other air environment is good areas, voltage levels are not too high occasions, still has its advantages, fiber optic cable with the lower prices, technology continues to mature and improve, the performance of fiber optic cable to be further improved, the structure of the cable with the use of the environment organic combination, to avoid irregularities in construction, economical ADSS cable or have a certain market space.