What effect does sustained voltage above the breakdown voltage have on XLPE cable?

Sustained voltage above the breakdown voltage can lead to possible further deterioration of XLPE (cross-linked polyethylene) cable. When the operating voltage exceeds the breakdown threshold, it can cause dielectric breakdown, where the insulation material may begin to fail. This failure can create partial discharges, which are essentially small electrical sparks that can cause further damage to the insulation over time.

As the cable experiences these high-stress conditions, the heat generated by sustained over-voltage can accelerate aging and degradation processes within the insulation material. Consequently, the structure of the XLPE can weaken, reducing its insulating properties and potentially leading to failure or increased risk of short circuits. This deterioration emphasizes the importance of adhering to specified voltage ratings to maintain the integrity and reliability of the cable.