The impact of wire and cable laying methods on their service life can be comprehensively and quantitatively assessed through dimensions such as insulation aging rate, mechanical damage risk, changes in heat dissipation performance, and differences in environmental adaptability. Different laying methods result in significant differences in the physical environment and stress state of the cable, which directly affect the cable's insulation, conductor, and sheath materials, thus impacting its long-term operational stability.
In direct burial, wires and cables are directly buried underground. Soil moisture, pH, and microbial activity accelerate the hydrolysis and corrosion of the insulation layer. If the soil moisture content is high, water easily penetrates into the insulation layer, forming conductive channels and reducing insulation resistance. If the soil is acidic or alkaline, chemical corrosion can damage the molecular structure of the sheath material, leading to embrittlement and cracking. Furthermore, directly buried cables are prone to localized insulation breakdown due to mechanical damage when subjected to excavation or geological changes, shortening their service life.
Aerial cables are exposed to the outdoor environment for extended periods. Ultraviolet radiation can damage the molecular chains of the insulation material, causing its surface to become brittle and crack. Weathering and wind erosion can also lead to sheath wear, reducing protective performance. During hot seasons, direct sunlight significantly increases the surface temperature of cables, accelerating the aging process of the insulation layer. In cold regions, low temperatures may cause the sheath material to shrink, leading to stress cracking. Without protective measures against sunlight and corrosion, the service life of overhead cables can be drastically shortened due to environmental factors.
Cable tray installation uses metal or non-metal trays to support and fix cables, effectively reducing the risk of mechanical damage. The open structure of the tray facilitates ventilation and heat dissipation, reducing the temperature rise of cables during operation and slowing down the aging of insulation. However, if the tray material is not properly selected or the installation process is flawed, such as metal trays lacking anti-corrosion treatment or burrs at tray connections, it may cause wear or electrochemical corrosion to the cable sheath, affecting its service life. Furthermore, cable tray installation requires space, which may limit its application in space-constrained locations.
Conduit installation runs wires and cables through metal or plastic conduits. The conduits provide excellent mechanical protection for the cables, effectively preventing damage from external forces. Simultaneously, the conduits isolate moisture and chemicals from the soil, reducing the risk of moisture and corrosion to the insulation layer. However, improper selection of pipe materials, such as using easily aging plastic pipes or metal pipes with poor corrosion resistance, may compromise cable safety due to pipe damage. Water accumulation or debris within the pipes can hinder cable heat dissipation, leading to excessively high localized temperatures and accelerated insulation aging.
Tunnel laying involves laying multiple cables centrally in dedicated tunnels. The tunnel environment is relatively stable, effectively controlling temperature, humidity, and dust levels, providing favorable operating conditions for the cables. The tunnel's ventilation and drainage system further optimizes cable heat dissipation and moisture protection, extending service life. However, tunnel construction is costly, and regular maintenance is required to ensure the tunnel environment meets requirements. Fires or flooding within the tunnel can severely damage the cables.
Cable trench laying combines the features of direct burial and cable tray laying. Cables are laid in trenches excavated on the surface, and the trenches are covered for protection. Cable trench laying facilitates cable installation and maintenance and effectively prevents external damage. However, if drainage in the trench is poor, water may seep into the cable, causing insulation failure. Conversely, if the cables are too densely packed within the trench, heat dissipation may be impaired, leading to excessively high localized temperatures.
Quantifying the impact of wires and cables laying methods on their lifespan requires comprehensive consideration of environmental factors, mechanical stress, heat dissipation conditions, and ease of maintenance. By establishing mathematical models or conducting simulations, the insulation aging rate, mechanical damage probability, and heat dissipation efficiency of wires and cables under different laying methods can be predicted and evaluated, thus providing a scientific basis for cable selection and laying design.
