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Repair measures for scratch and damage of cable sheath surface during cable laying on site

by:AAA     2020-03-24
In the process of on-site cable laying, it is common that the surface of the cable sheath is scratched and damaged. Only the sheath is damaged slightly. How to repair can ensure the quality and the repair time is short, it is also a common concern for cable consumers to ensure quality. Moreover, the investment is small and it is easy to realize under the harsh conditions on site. Therefore, the repair technology and quality of the on-site sheath are increasingly becoming the concern of users. The on-site construction conditions of the cable are generally relatively poor, which may be located in the power plant under preliminary construction, the newly-built railway in the field under preliminary construction, the bridge or the cable tunnel, because the repair of cable sheath in the field is carried out by plastic welding gun, and the heating of plastic welding gun needs 220 v ac, while the field project in the emerging construction generally lacks power supply, or the power supply may bring some difficulties to the supply of power supply due to the immediate location of the cable laying on site. Therefore, to repair the cable sheath, on the one hand, the personnel are in place, on the other hand, it is mainly the provision of power supply. Only by making the above two basic preparations can the cable sheath repair work be carried out and carried out normally. In order to facilitate the smooth progress of cable repair work, the construction unit should be equipped with field small generators. At the same time, it is convenient to repair on site. The quality of the plastic welding gun now provided should be excellent. The heating area of the nozzle should be large and the heating speed should be fast. Moreover, the damaged parts of the cable pay-off process are random. In general cities and plain areas, this work is relatively easy to carry out, but in some mountainous areas, due to the influence of complex terrain, the repair of cables is actually very difficult. Therefore, in order to reduce the investment in corresponding aspects and solve the problem quickly, a key problem is that the number of personnel in the cable laying process must be sufficient, and regular cable laying equipment must be used for regular laying, avoid and reduce the phenomenon of sheath damage during cable pay-off. The technology required for on-site repair of cables is not very high. After the cable is damaged, the cable laying construction unit must confirm that the inside of the cable is not damaged, then repair the cable, otherwise the practical significance of cable sheath repair is not great. The repair of the cable must be timely, otherwise the external moisture and moisture will enter over time, which will affect the normal production and service life of the cable. After the end of the cable is laid in southern Meiyu weather, the end of the cable is not sealed in time, resulting in moisture flowing into the cable trench entering the cable end 10- 20 meters, the insulation of the stripping end found that the conductors have all been black, resulting in the waste of the cable after the laying, so for the cable that has been laid, it is necessary to strengthen the inspection of the corresponding aspects, maintenance and storage to prevent the shortening and termination of cable life caused by various external factors on site before the cable is powered on. Some tools and materials used for on-site repair of cables must be fully prepared. Plastic welding gun is necessary. High-voltage insulation tape, waterproof tape, plastic insulation and sheath peel off the cut leather, such as sealing materials, must also be prepared, because the cable insulation sheath material is mainly divided into cross-linked polyethylene, polyethylene, polyvinyl chloride and other materials. Some materials belong to thermosetting materials. For example, cross-linked polyethylene insulation cannot be melted and reused repeatedly, and is repaired with raw materials on site, it can only be repaired with high-voltage insulation tape and the repair tape series provided by US 3M Company. However, some materials belong to thermoplastic materials and can be melted and utilized by high temperature again. China's wire and cable network (Cable 315 Network)www. Xianlan315. Com such as polyethylene, polyvinyl chloride and other materials can be obtained on site, and the corner sheath material cut off by the end of the cable can be cut into thin strips to repair the insulation and sheath of low-voltage cables, the repair quality can completely meet the requirements of the normal use performance of the cable. For medium voltage cables, the treatment of sheath damage in the field laying process should not be too rough. One is that the cable laying process must be handled with care, and the other cable is externally damaged, the damage of its internal insulation is sometimes difficult to say. The author has carried out a factory return test on cables with multiple damage of the outer sheath caused by careless construction during the on-site laying process, it is found that partial discharge exceeds the standard and breakdown occurs in the damaged part of the cable. Therefore, after the outer sheath of the medium voltage power cable is damaged during the on-site laying process, it is better to cut off the intermediate joint or replace the cable again, because the cable damaged parts of the sheath repair, there may be hidden dangers. Facts have proved that the repair of low-voltage cable insulation and sheath must be a slight damage to the cable, only if the insulation and sheath are damaged and other cable structures are intact, only in this way can the insulation and sheath be repaired, and the requirements of medium and high voltage cables may be more stringent. In order to reduce the number of intermediate connectors of cables, all cables adopt large-length single-core cables. Due to the long laying distance of the line, the responsibility of the terrain, the number of construction personnel and the lack of professional cable laying equipment and other factors, the probability of cable sheath damage caused by the construction process is greatly increased. After some of the above problems occurred in the construction, it was very irresponsible to wrap it up with ordinary adhesive tape and hastily manage it. I know nothing about the damage inside the cable damage point, and insulation breakdown or quality hidden danger is likely to occur during the on-site completion test and later Operation of the cable.
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