NEWS

As my country's industrial level is getting higher and higher, it can be said that wires and cables are almost everywhere. In recent years, the construction of cables into the ground has developed very rapidly. However, with the increasing number of cable lines and the increase in operating years, cable failures With the gradual increase, the faults of the cable body, cable accessories, cable accessories and other equipment that occur in the operation of the cable have also increased significantly. Now let's take a look at the reasons for these faults.

As the use time of the cable increases and accumulates, the most likely problem with the cable is the aging of the insulation. The reason for this may be that the cable did not choose a suitable model when it was laid, resulting in the cable working under overvoltage for a long time or the cable line. There is a heat source nearby, which makes the cable part or the entire cable line heat up for a long time and prematurely age. The working environment of the cable is also a factor that affects the life of the cable insulation. If it is used in a bad chemical reaction environment, or multiple cables are running in parallel but one or several of them are in poor contact, it will also cause other parallel cables to pass through. Load operation will cause failure. When the cable accessories are made, the cable connection tube is not crimped firmly, resulting in increased contact resistance and overheating. These are the causes of insulation failure and must be avoided reasonably.

The accessories are also very prone to problems, and this ratio is also very high. The reason is that the cable intermediate joints and terminal heads are usually completed by the installer on-site at the laying site. Problems with the accessories will affect the discharge of the composite interface and the aging of the material of the accessories. The problem of accessories is often caused by poor production process and poor product quality. During the production process, defects such as air bubbles, moisture and impurities appear in the accessories, resulting in partial discharge and insulation breakdown. It is not only necessary to choose high-quality accessories, but also during the installation process. Nor can it be neglected.

The problem of the outer sheath is also relatively common. In the medium and high voltage power grid, the outer sheath of the wire and cable is the first line of defense to protect the cable. Its integrity is directly related to the safety of the internal structure and the service life of the cable. The reasons for the problems of the outer sheath are: there are hard objects up and down the buried cable, and the sharp corners directly contact the outer sheath, especially in the section with vehicles passing through, the road surface vibrates for a long time, and the sharp corners of the hard objects may pierce the outer sheath, This leads to damage to the internal structure, coupled with the change of cable load, the thermal expansion and contraction of the cable itself and the uneven distribution of the electric field in the damaged part, resulting in damage to the insulation layer; when the pipes are laid, the steps or inner walls of the pipe connections are not smooth. It may cause damage to the outer sheath; mechanical construction or pipe jacking around the cable path may cause damage to the outer sheath.

During the cable laying process, the outer sheath is pulled and the cracked part is in the pipe, so it will not be found in time; after a period of operation, cracks occur, the insulation of the outer sheath is reduced, the metal sheath is grounded at multiple points, and the circulating current increases. large, eventually leading to thermal aging breakdown of the insulation. Termite erosion is also one of the reasons for the appearance of the outer sheath. Once a termite erosion part is found, there should be multiple erosion parts on the cable line, and we should pay enough attention. Termites are endangered, and relatively few in the north.