Performance characteristics of composite insulators
Composite insulators have strong weather resistance and good self-cleaning performance inside the components. It only needs to check the pollution once every 4-5 years, and the maintenance and disconnection time is shorter. Due to the high tensile strength of the mandrel, the overall weight of the composite insulator is very light. Their weight is only 10-20% of that of porcelain insulator strings of the same voltage level. Under the same rated voltage, their length can be shortened by about 10%, which can significantly reduce the labor of transportation and field operation workers.
Composite insulators have many advantages, but also disadvantages such as loss of hydrophobicity, brittle and broken mandrels, risk of lightning strikes and bird falls, which all make composite insulators ineffective.
Due to the smaller diameter of the shed of the composite insulator, its minimum arc distance is smaller than that of the porcelain insulator string of the same length, and the lightning resistance level is also smaller than that of the same length of the porcelain insulator string.
After a lightning strike, the only effect on composite insulators is white lightning erosion. There is no change in their insulating properties. But attention must be paid to corrosion at the end of the fitting.
The inner insulation distance of the composite insulator is almost equal to that of the outer insulator, and it is constructed as a part of the puncture-proof insulator group, so there is no need to test the zero-value insulator, which greatly reduces the insulation coefficient of the insulator. insulator. Operation and maintenance workload.
Composite insulators have silicone rubber shed and sheath materials with low energy surfaces. The composite insulator has a large creepage distance, a small shed diameter, and a hydrophobic migration surface. Even in humid and polluted environments, the shedding surface of composite insulators does not form a continuous water film. Therefore, it is superior to porcelain insulators in terms of pollution resistance.
The main component of composite insulators is a silicone rubber sheath. Silicone rubber is formed by bonding polymers of polydimethylsiloxane and organic oxygen compounds. The main chain is formed by silicon-oxygen bonds. Due to the high bond energy of the silicon-oxygen bond, it is thermally stable and can operate at temperatures from -100 to + 350°C. Silicone rubber has good ozone resistance, while butadiene-propylene-butadiene rubber is easy to break, and under 150ppm ozone pressure at room temperature, silicone rubber can last for several months without breaking.
