Do you know what problems are prone to occur with wires and cables during operation?

With the increasing industrial level in our country, it can be almost said that wires and cables are everywhere. In recent years, the construction and development of cable grounding have also been very rapid. However, with the increasing number of cable lines and the growth of operating years, cable faults have gradually increased. The number of faults that occur in cable operation, such as cable body, cable accessories, and cable accessory equipment, has also increased significantly. Now, let's take a look at the causes of these faults together.

As the cable usage time increases and accumulates, insulation aging is the most common problem with the cable. The reason for this situation may be that the cable was not laid with a suitable model, resulting in the cable working under overvoltage for a long time or being close to heat sources around the cable line, causing local or entire cable lines to be heated for a long time and aging prematurely. The working environment of cables is also a factor that affects the lifespan of the cable insulation layer. If used in an unfavorable environment with chemical reactions, or if multiple cables are operated in parallel but one or more of them have poor contact, it can also cause overload operation of other cables in parallel, leading to faults. When cable accessories are made, the cable connection pipe is not firmly pressed, causing an increase in contact resistance and overheating, These are all the causes of insulation faults, and they must be reasonably avoided.

Attachments are also very prone to problems, and this proportion is also very high. The reason is that cable intermediate joints and terminal heads are usually completed by installation personnel on site during installation. If installation is not done carefully, it is easy to make mistakes. Problems with attachments can affect composite interface discharge and aging of accessory materials. Attachment issues are often caused by poor manufacturing techniques and poor product quality. During the manufacturing process, defects such as bubbles, moisture, and impurities may appear inside the attachment, leading to partial discharge and insulation breakdown. It is not only necessary to choose high-quality attachments, but also not to neglect them during installation.

The issue of outer protective layer is also quite common. In medium and high voltage power grids, the outer protective layer of wires and cables is the first line of defense to protect cables. Its integrity directly affects the safety level of the internal structure and the length of cable service life. The causes of problems with the outer protective layer include: hard objects and sharp corners on the buried cable that directly contact the outer protective layer, especially in road sections with vehicular traffic. Prolonged road vibration can cause sharp corners of hard objects to penetrate the outer protective layer, leading to internal structural damage. In addition, changes in cable load can cause thermal expansion and contraction of the cable itself, as well as uneven distribution of electric fields in damaged areas, resulting in damage to the insulation layer; When laying pipes, uneven steps or inner walls at the connection of the pipes may cause damage to the outer protective layer; Mechanical construction or pipe jacking around the cable path may cause damage to the outer protective layer.

During the laying and construction process of cables, the areas where the outer protective layer is pulled or cracked may not be detected in a timely manner if they are inside the conduit; After running for a period of time, cracking occurs, the insulation of the outer protective layer decreases, the metal sheath is grounded at multiple points, and the circulating current increases, ultimately leading to insulation aging and breakdown due to heating. Termite erosion is also one of the reasons for the appearance of the outer protective layer. Once a termite erosion site is found, there should often be multiple erosion sites on the cable line, and we should pay enough attention to it. Termites are at risk of erosion and are relatively rare in the north.