The base material of RTV anti-pollution flashover coating is a special siloxane polymer compound, the molecular chain is Si2O2Si, and the substituent or side chain is C2H structure.
The methyl group (organic group) in the polysiloxane molecule is connected to the main chain, and the Si atom forms an umbrella-shaped space configuration of an inverted regular tetrahedron. Since the H atom is the atom with the smallest van der Waals atomic radius, the umbrella-like methyl structure they form is closely arranged to form a closed barrier to keep water molecules out of the barrier. When rain or dew drops on the surface of the coating, they will automatically roll off, or one by one scattered on the surface of the coating, which will not form a continuous water chain or spread into a water film, showing extremely excellent water repellency.
Therefore, the anti-pollution flashover mechanism of RTV coatings can be analyzed from several aspects such as hydrophobicity, hydrophobic migration performance, and voltage distribution:
1. Good hydrophobicity
After the RTV anti-pollution flashover coating is applied to the surface of the insulator, the formed coating covers the entire surface of the insulator and isolates the insulation product from contact with contaminants. When the contaminant material falls on the surface of the insulator, it touches the coating of the RTV anti-pollution flashover coating. The performance of the coating becomes the surface performance of the insulator.
2. Even voltage distribution
Because RTV coating has strong hydrophobicity, it is difficult to form a continuous conductive layer on the surface of dirt, so there will be no uneven voltage distribution.
3. Hydrophobic mobility
The materials only with hydrophobicity cannot be used as anti-pollution flashover coatings for insulators, and must have excellent hydrophobic mobility. When pollution accumulates on the surface of the RTV, the free hydrophobic substances in the RTV gradually expand to the dirty surface, so that the dirty layer is also hydrophobic, not wetted by rain or moisture in the mist, not ionized, and thus can effectively inhibit current leakage, greatly improving the anti-pollution flashover capability of the insulator. Therefore, hydrophobic migration is one of the key indicators of the anti-pollution flashover performance of RTV coatings.