Why is hydrophobicity retention important in polymer insulators?

• A. Retained hydrophobicity lowers leakage currents by keeping the surface water-repellent, limiting continuous wetting.
• B. Retained hydrophobicity increases leakage currents.
• C. It has no effect on leakage; only affects color.
• D. It improves dry withstand voltage but not leakage.

Answer: (D)

Hydrophobicity retention on polymer insulators means the surface keeps its water-repellent properties even after weathering. This helps a lot in dry conditions because a dry, water-repellent surface resists the formation of moisture films that can create continuous conductive paths along the surface. That protection raises the voltage the insulator can withstand when there’s no moisture, i.e., the dry withstand voltage goes up.

But leakage current is driven mainly by the presence of moisture and contaminants forming a conductive path on the surface. Even if the surface remains hydrophobic, real-world pollution and rain can still wet the surface enough to allow leakage currents to flow. In other words, the retained hydrophobicity does not guarantee a significant reduction in leakage under wet or polluted conditions, whereas it does improve performance when the surface is dry. That’s why the statement that it improves dry withstand voltage but not leakage fits the concept being tested.