In addition to meeting high electrical performance requirements, high-voltage overhead cable insulation also requires excellent weather resistance to ensure safe operation under long-term sunlight exposure. Existing overhead cable insulation materials are composed of polymer insulating materials and a certain amount of carbon black. While polymer insulating materials can block over 94% of visible and infrared light, preventing its penetration, a small amount (6% of total energy) of ultraviolet (VA) light can still penetrate the insulation. Over time, this causes polymer degradation, roughening and even cracking of the insulation surface, ultimately leading to insulation failure.
Adding more than 2% carbon black to the insulation can completely prevent VA light intrusion, but this is detrimental to the cable's electrical insulation performance, causing a sharp increase in the γ value. To resolve this contradiction, the optimal weather-resistant cross-linked insulation formula was determined after various formulations and numerous experiments. This formula has been successfully pilot-produced by some domestic manufacturers, and cross-linked overhead cables produced using this material have been officially put into operation.