During the on-site laying of cables, the phenomenon of scratches and damages on the surface of the cable sheath is common. If the damage is slight, only the sheath is damaged. How to repair can ensure the quality, and the repair time is short and the quality can be guaranteed. issues of general concern. In addition, the investment is small, and it is easy to realize under the harsh conditions of the field. Therefore, the repair technology and quality of the field sheath have increasingly become the concerns of users.
The on-site construction conditions of cables are generally poor. They may be located in power plants under preliminary construction, or in newly-built railways in the field under preliminary construction. They may be on bridges, or in cable tunnels. Because the repair of cable sheaths in the field is made of plastic. The welding torch is used for heating, and the heating of the plastic welding torch requires 220V AC power. In the field projects under emerging construction, the site generally lacks power supply, or the power supply may be due to the randomness of the laying position of the site cable, which brings a certain amount of power supply. Therefore, to achieve the repair of the cable sheath, on the one hand, the personnel are in place, and on the other hand, it is mainly the supply of power. Only by doing the above two basic preparations can the normal development and progress of the cable sheath repair work. .
In order to facilitate the smooth progress of the repair work of the cable shelter, the construction unit should be equipped with a small generator in the field. At the same time, it is convenient for on-site repairs. The quality of the plastic welding guns now provided should be excellent. The heating area of the nozzle should be large and the heating speed should be fast. In addition, the damaged parts of the cable are random in the process of laying out. 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 work of cables is actually very difficult. Therefore, in order to reduce the investment in the corresponding aspects and solve the problem quickly, a very key problem is that the number of personnel in the cable laying process must be sufficient, and regular professional cable laying equipment is used for regular laying out, so as to avoid and reduce the occurrence of cable laying. The phenomenon of sheath damage.
The technology required for on-site repair of the cable is not very high. After the cable is damaged, the cable laying construction unit must repair the cable under the premise that the cable is not damaged. Otherwise, the actual repair of the cable sheath It is not meaningful. The repair of the cable must be timely, otherwise, the entry of external moisture and moisture over time will affect the normal production life of the cable. In the rainy weather in the south, after the end of the cable was laid, the end of the cable was not sealed in time, causing the water flowing into the cable trench to enter the broken end of the cable for 10-20 meters, and the insulation of the end was peeled off. All the cables have been turned black, resulting in waste of cables after laying. Therefore, it is necessary to strengthen the inspection, maintenance and storage of the laid cables to prevent the cables from being shortened and terminated due to various external factors on the site before they are energized and used. .
Some tools and materials used for on-site repair of cables must also be fully prepared, plastic welding guns are necessary, high-voltage insulating tape, waterproof tape and plastic insulation and sheathing peeled off the skin, and other sealing materials must also be prepared, because the cable Insulation sheath materials are mainly divided into cross-linked polyethylene, polyethylene, polyvinyl chloride and other materials. Some materials are thermosetting materials, such as cross-linked polyethylene insulation, which cannot be re-melted and reused. It can only be repaired with raw materials on site. It can only be repaired with high-voltage insulating tape and the repair tape series provided by 3M Company in the United States. And some materials are thermoplastic materials, which can be melted and used again at high temperature, such as polyethylene, polyvinyl chloride and other materials. Some materials can be obtained on site and cut into thin strips by using the corner sheath material peeled off from the end of the cable. It can repair the insulation and sheath of the low-voltage cable, and the repair quality can fully meet the requirements of the normal use performance of the cable. Another thing is to deal with the damage of the sheath that occurs during the on-site laying of medium-voltage cables, and it should not be too rough. One is that the cable must be handled with care during the laying process. Another is that after the external damage of the cable occurs, the damage to its internal insulation is sometimes It’s hard to say, the author once carried out the factory return test on the cable whose outer sheath was damaged in many places due to careless construction during the on-site laying process. When the outer sheath is damaged during the on-site laying process, it is best to cut off the intermediate connector or replace the cable, because there may be hidden dangers in the use of the damaged part of the cable after the sheath is repaired.
Facts have proved that for the repair of low-voltage cable insulation and sheath, the cable damage must be relatively minor, only if the insulation and sheath are damaged, and other structures of the cable are intact, the insulation and sheath can be repaired. The requirements for cables may be more stringent. In order to reduce the number of intermediate joints of cables for power transmission in some projects, all cables use large-length single-core cables. Due to the long laying distance of the line and the responsibility of the terrain, as well as 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 the above-mentioned problems occur in some construction projects, they just wrap a bag with ordinary tape, which is very irresponsible. Knowing nothing about the damage inside the cable breakage point, the cable is likely to have insulation breakdown or hidden quality problems during the on-site completion test and later operation.