What effect does high temperature have on transformer insulation?

High temperatures can significantly affect transformer insulation, primarily by reducing its effectiveness. Insulation materials are designed to operate within specific temperature ranges. When temperatures rise beyond these thresholds, the insulation can degrade more rapidly due to thermal stress. This degradation can lead to a decrease in dielectric strength, which is the measure of an insulation material's ability to withstand electrical stress without breaking down.

As the insulation becomes less effective, it increases the risk of electrical faults or failures within the transformer. Over time, the heat can also cause physical changes in the insulation material, such as embrittlement or cracking, which compromises its ability to insulate effectively. Thus, the impact of high temperature on transformer insulation is primarily negative, making the insulation less reliable and potentially leading to severe operational issues.