5 reasons for high-voltage cable failure and their solutions

       Fire caused by cable failure is fierce and spreads rapidly. A large amount of harmful gas will be produced during combustion, making it difficult to extinguish. After the cable is burned, the repair time is long and the loss is serious, so it is important to pay attention to preventing cable fire accidents. The following are 5 reasons for high-voltage cable failure summarized by Shanghai Qiyue High Temperature Cable:

1. The site conditions are relatively poor. The environment and process requirements for cables and connectors are very high when they are manufactured in the factory, and the temperature, humidity and dust at the construction site are not easy to control.

2. During installation, the process was not strictly followed or the process regulations did not take into account possible problems. The DC withstand voltage test was used for completion acceptance, which caused the formation of a reverse electric field in the connector, resulting in insulation damage.

3. It was caused by poor sealing. The intermediate connector finally adopts a sealing structure with a metal copper shell and a PE or PVC insulation anti-corrosion layer. The lead seal is ensured to be dense during on-site construction, which effectively ensures the sealing and waterproof performance of the connector.

4. During the cable construction process, it is inevitable that small scratches will be left on the insulation surface. Semi-conductive particles and sand on the emery cloth may also be embedded in the insulation. In addition, during the joint construction process, the insulation is exposed to the air and moisture will be absorbed into the insulation, which will leave hidden dangers for long-term overload operation.

5. The defects that are inevitable in the cable material itself and the cable manufacturing, laying, terminal production, etc. are affected by the electric heat, chemistry, environment and other factors during operation. The insulation of the cable will age to varying degrees, and this aging will eventually lead to cable failure.

During the on-site laying of the cable, the surface of the cable sheath is scratched and damaged. The minor damage only damages the sheath. How to repair it to ensure quality, and the repair time is short, and the quality is guaranteed is becoming a common concern of cable consumers. Moreover, the investment is small and it is easy to achieve under the harsh conditions on site. Therefore, the on-site sheath repair technology and quality are becoming a concern of users.

The on-site construction conditions of cables are generally bad. They may be located in a power plant under preliminary construction, or in a newly constructed field railway under preliminary construction, or on a bridge, or in a cable tunnel. Because the repair of field cable sheaths is carried out by plastic welding, and the heating of plastic welding requires 220V AC power, and the field projects under new construction generally lack power on site, or the power supply may be due to the randomness of the laying position of the on-site cables, which brings certain difficulties to the supply of power. Therefore, to achieve the repair of cable sheaths, on the one hand, it is necessary to have personnel 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 cable sheath repair work be achieved.

In order to facilitate the smooth progress of cable repair work, the construction unit should be equipped with a small field generator. At the same time, the quality of the plastic welding provided now should be excellent for the convenience of on-site repair. The nozzle heating area should be large and the heating speed should be fast. In addition, the damaged parts of the cable laying process are random. In general cities and plains, this work is easier 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 corresponding investment and quickly solve the problem, a key issue is that the number of personnel equipped in the cable laying process must be large enough, and regular cable laying equipment must be used for regular cable laying to avoid and reduce the phenomenon of sheath damage during the cable laying process.