The insulation of cables within bridge structures relies solely on the outer sheath. If not properly protected, it can be corroded over time by external gases, significantly reducing its insulation. Gradually, it may also become aged and hardened, eventually leading to detachment. At this point, the insulation effect is lost. Generally, cable insulation is made of plastic and rubber; what causes its aging?
Insulating under humid conditions.
Cable joints typically occur in buried or conduit installations. For instance, if an improperly qualified cable joint is installed in a humid environment, moisture or steam can seep into the joint, leading to the formation of water trees under the presence of an electric field. This directly affects the cable's insulation, potentially causing faults and issues within the company.
Corrosion of chemical raw materials.
Burial of cables can directly lead to acidic and alkaline interactions in areas where the cable tray, armor cable, or lead sheath corrosion of the outer jacket occurs. Subsequently, the protective layer is subjected to chemical and electrolytic corrosion, followed by its destruction, insulation reduction, and even cable failure.
3. Operating under long-term overload.
It is known that when a cable carries load current, the conductor heats up, causing the cable temperature to rise. This accelerates insulation aging, which can lead to long-term breakdown, especially during summer, making cable tray failures more severe.
Cable joint failure.
In fact, the system failure we experienced was likely caused by improper operation by the management staff. For instance, issues such as loose connections and insufficient heating during the cable joint assembly process by construction technicians can lead to a decrease in the insulation performance of the cable heads.
5. Environmental and Temperature Factors
External environment and temperature also affect cable trays. At high temperatures, insulation breakdown or even explosions and fires can occur.
6. External Damage.
Many current cable failures are predominantly caused by mechanical damage. For instance, when cables are laid and installed, if our construction techniques and operations are not standardized, it can easily lead to mechanical damage in our country. Sometimes, the damage may not seem severe at the time, but after a period of work, the cost will begin to escalate, leading to a complete breakdown and failure. Severe cases can cause short circuits, directly impacting the safety education of production enterprises using bridges and electricity.