Silicone insulator coating is made of silicone rubber and plays a role of hydrophobicity (water-repellency) in the insulator operation.

Silicone insulator coating hydrophobicity:
Hydrophobicity recovery of an RTV Silicone insulator coating is most critical for long term performance in preventing corona, partial discharge and pollution flashovers.
The superior electrical performance of composite insulators and Silicone insulator coating stems from the hydrophobicity (water-repellency) of their surfaces. The hydrophobicity will change with time due to exposure to the outdoor environment and partial discharges (corona).
Seven classes of the hydrophobicity (HC1 to HC7) have been defined. HC-1 corresponds to a completely hydrophobic (water-repellent) surface and HC-7 to a completely hydrophilic (easily wetted) surface.

In order to know the extent of Silicone insulator coating 'hydrophobicity recovery':
Hydrophocity of the virgin coating sample is measured
Hydrophocity of the coating is purposely destroyed by 100 hours of continuous exposure to corona.
Thereafter, the hydrophobicity is checked again after 48 hours: This reading is what is most important

In addition to Silicone insulator coating hydrophobicity, there are also other properties of silicone insulators coating shown on Orient Power website, and if you want to learn of them, just visit Orient Power website freely.
 

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