Why can overhead insulated cables significantly reduce short-circuit failure rates in urban power grid retrofits?
Publish Time: 2025-10-03
With the acceleration of urbanization and the continuous growth of electricity loads, urban power grids face multiple challenges, including aging equipment, densely packed lines, and complex environments. Traditional overhead lines generally use bare conductors. While cost-effective, these conductors, exposed to the outside world, are highly susceptible to short-circuit failures caused by various external factors, seriously impacting power supply reliability. In recent years, overhead insulated cables, due to their superior safety and stability, have become the preferred cable type for urban power grid retrofits and community power construction. Combining power transmission and mechanical protection, they effectively address various risks in complex urban environments, significantly reducing short-circuit failure rates and improving grid operation continuity and safety.1. Preventing Interphase Short Circuits from Foreign ObjectsIn urban environments, wind-blown foreign objects are one of the main causes of short circuits in overhead lines. Traditional bare conductors are limited in distance. If conductive or moist foreign objects connect two or more conductors, interphase short circuits can easily occur, causing tripping and even equipment damage. Each conductor of overhead insulated cables is wrapped in a high-density insulating material. Even if foreign objects come into contact or overlap, they cannot directly connect the conductors, effectively eliminating short-circuit paths. This "self-protection" capability significantly reduces sudden failures caused by foreign objects and is key to reducing short-circuit rates.2. Avoiding Tree Contact to Reduce Ground FaultsUrban green belts and residential roads are lush with trees, whose branches and leaves grow rapidly. In windy and rainy weather, branches can easily swing and contact bare conductors, causing single-phase grounding or ground discharge, triggering line tripping. This risk is particularly heightened during humid seasons, when leaves contain high moisture content and enhance conductivity. The insulation layer of overhead insulated cables effectively prevents direct contact between branches and conductors. Even if branches rub against or press against the cable for extended periods, a ground path will not form as long as the insulation layer is not completely broken down. This significantly improves line operation stability in densely green areas and significantly reduces ground faults caused by tree obstructions.3. Withstands severe weather and improves environmental adaptabilityUrban areas are prone to unpredictable weather, with frequent extreme weather events such as thunderstorms, strong winds, snow, and smog. Bare conductors can easily form conductive paths due to water film in rainy and foggy weather, increasing the risk of flashover. Accumulation of ice and snow can cause line sagging and increased swaying, leading to wire collisions. The insulation layer of overhead insulated cables is highly hydrophobic and weather-resistant, effectively preventing rainwater from forming a continuous conductive layer along the surface, reducing the likelihood of wet flashover. Furthermore, the insulation layer is resistant to UV rays and high and low temperatures, ensuring it resists aging and cracking under long-term exposure to sunlight and rain, maintaining stable insulation strength.4. Reduces animal damage and improves operational safetyBirds, squirrels, and other small animals are active in cities and urban-rural fringe areas, often nesting or climbing on the crossarms of power poles. This can easily lead to bird pecking, rat biting, or their bodies bridging the wires, causing short circuits. The outer sheath of overhead insulated cables is typically made of high-strength materials, offering a certain degree of resistance to gnawing. Even with minor damage, the remaining insulation thickness maintains normal operation and prevents immediate breakdown. Some models are also designed with animal-proof or bird-sting-proof covers to further reduce the risk of biohazards.5. Supports live-line work, reducing the risk of construction failuresDuring urban power grid renovations, frequent power outages can impact electricity supply to residents and businesses. Overhead insulated cables support a certain degree of live-line work, allowing maintenance personnel to perform wiring, replace insulators, and other operations without interrupting the power supply. The insulating sheath provides an additional safety barrier for workers, reducing the risk of short circuits caused by operator error. Furthermore, their compact structure facilitates installation in confined spaces, minimizing interference with surrounding lines during construction.Overhead insulated cables, through the physical isolation provided by the insulation layer, effectively prevent short circuits caused by foreign objects, tree contact, animal damage, and inclement weather, significantly improving the reliability of urban power grids. Compared to traditional bare conductors, they not only reduce the failure rate but also reduce inspection and maintenance frequency, extend line life, and lower overall operation and maintenance costs. As urban power grids evolve towards smarter, safer, and more reliable systems, overhead insulated cables have become an indispensable core component, providing stable and secure power supply for modern cities.
