Voids within the high voltage insulation of underground cable can lead to failure due to what reason?

Voids within the high voltage insulation of underground cable can lead to failure due to ionization of air voids causing scorching. This phenomenon occurs when the air trapped in the voids becomes ionized under the influence of the high electric fields associated with high voltage cables. Ionization can increase the conductivity of the air, creating a path for electrical discharge. This can lead to localized overheating and damage to the insulation. The resulting scorching can compromise the integrity of the insulation material, potentially leading to partial discharges, which further deteriorates the insulation and may eventually result in complete failure of the cable. This emphasizes the importance of ensuring that underground cables are properly installed and that voids are minimized to maintain long-term reliability and safety.