1. Reasons and hazards of spiral cables getting wet and entering the water
1) When the new cable is shipped from the factory, both ends are sealed with plastic sealing sleeves. However, after a section is used according to the actual situation at the construction site, the remaining part is simply wrapped with plastic cloth. If it is not placed and sealed well, over time, water vapor will inevitably seep into the cable.
2) When laying cables, it is necessary to often cross roads, bridges and culverts. Due to weather or other reasons, a lot of water often accumulates in the cable trenches. During the laying process, it is inevitable that the cable head will be immersed in water. Water enters the cable due to loose or damaged plastic wrapping;
In addition, during traction and pipe penetration, the outer sheath or even the steel armor is sometimes scratched, and this phenomenon is particularly prominent when mechanical traction is used.
3) After the cable laying is completed, the cable head cannot be made in time due to the limitations of the site construction conditions, so the unsealed cable fracture is exposed to the air for a long time, or even immersed in water so that a large amount of water vapor enters the cable.
4) During the production process of the spiral cable head (including the terminal head and the intermediate joint), due to the negligence of the construction personnel, the newly processed cable end sometimes accidentally falls into the stagnant water on site.
5) In the normal operation of the cable, if there is a breakdown such as a breakdown for some reason, the water in the cable trench will enter the cable along the fault point; in civil construction, especially in the use of large construction machinery. In construction sites, cable breakage or breakdown accidents caused by various human factors are not uncommon. When such an accident occurs, the cable insulation is severely damaged, and it can also cause water to enter the cable.
Studies have shown that after the cable enters the water, under the action of the electric field, water tree aging will occur, and finally, the cable will break down. Water trees are collections of water-filled voids ranging from 0.1 m to several microns in diameter. The impurities, pores in the insulation, and the local high electric field formed by the unevenness of the joint surface between the insulation and the inner and outer semiconducting layers are the starting points of the water tree. The development process of a water tree is generally more than 8 years. The higher the humidity, temperature and voltage, the more ions contained in the water, and the faster the water tree develops.
2. The solution to the cable damp and water
1) Since the impurities and pores in the insulation are the starting point for the occurrence of water trees, the quality of the cable is very important to prevent the aging of the water trees. When purchasing cables, you must choose a manufacturer of excellent quality. The cables produced by Henan Verde Cable Co., Ltd have undergone rigorous testing, and you can rest assured of the quality!
2) Ensure that the cable head is well sealed. For the sawed cable end, whether it is stacked or laid, it must be sealed with plastic. It is best to use a special cable gland to prevent moisture from infiltrating.
3) After the wires are laid, the cable head should be made in time. If it cannot be made immediately due to the limitation of conditions, the cable head should be sealed and wrapped and placed overhead.
4) Improve the technical quality of construction personnel and strengthen the management of the production process of the spiral cable head, which can effectively prevent the cable head from entering the water during the production process.
The practice has proved that once the cable enters the water, the earliest breakdown phenomenon is often the cable head, so the wire head is well made, which can prolong the overall life of the cable.
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