Why is oil and gas-filled cable considered more practical for high voltage applications?

Oil and gas-filled cables are favored for high voltage applications primarily because of their reduced chance of air voids. In high voltage scenarios, the insulation's performance is critical, and air voids can significantly compromise the integrity of the insulation. When air is entrapped within the insulation, it can lead to dielectric breakdown and reduced insulation performance. Oil and gas serve to fill any potential voids within the cable insulation, which minimizes the risk of these detrimental air pockets forming.

Moreover, the presence of these materials enhances the electrical properties of the insulation, helping to maintain stability and reliability under high voltage conditions. This leads to better overall performance and longevity of the cable.

While lower thermal resistance, higher insulation costs, and enhanced flexibility might offer benefits in other contexts, they do not directly address the primary concern of air voids, which can have critical implications for safety and effectiveness in high voltage applications.