Composite insulators are different from traditional porcelain or glass insulators in terms of structure and materials, and their performance is also different from porcelain or glass insulators. They are summarized as follows:
(1) The axial tensile strength of the fiberglass core rod used in composite insulators is very high, generally above 600 MPa, which is 5 to 10 times that of porcelain and equivalent to high-quality carbon steel. In addition, the ratio of the core rod material is only 2.0, which is much lighter than steel; the ratio of the shed material is also less than 2.0. Therefore, composite insulators can easily produce strength levels with specified mechanical loads of hundreds of kilonewtons, and their mass is only 10% to 15% of that of disk-shaped suspension insulators. In mountainous construction and accident repairs, synthetic insulation is light in weight and not afraid of damage, so it is very popular among operation and construction personnel.
(2) Composite insulators have a rod-shaped insulator structure, and the distance between the inner and outer poles is almost equal. Generally, internal insulation breakdown does not occur, and there is no need to detect zero values.
(3) The composite insulating shed sheath material is an organic polymer material with a low surface and strong hydrophobicity. The water on the surface of the skirt condenses into many small water droplets that are separated from each other, and does not form a continuous water film conductive layer. The leakage current is small, it is difficult to form a local arc, and it is difficult to cause pollution along the surface. In addition, due to the high strength of the core rod, the rod diameter and umbrella diameter of the suspension insulator are much smaller than those of the porcelain insulator string, and the shape coefficient is large. Under the same dirt and the same surface conductivity, its surface resistance is higher than that of porcelain insulator strings with small shape coefficients. The pollution lightning voltage of insulators is directly related to the surface resistance. When the surface resistance is large and the leakage current is small, the corresponding pollution lightning voltage is the highest. Laboratory test results and operating experience confirm that composite insulators have high flash performance and flash accidents rarely occur.
(4) Easy operation and maintenance. The pollution flashover performance is high, and there is no need to clean up pollution or detect zero values. Currently, composite insulators under various voltage levels in China do not undergo traditional and heavy cleaning and zeroing maintenance work, which greatly reduces the maintenance workload.
