The main functions of composite insulators are to support conductors and prevent current from grounding.

A composite insulator is a special insulating component that plays an important role in overhead transmission lines. It is mainly composed of three parts: glass fiber epoxy resin pultruded rod, silicone rubber shed and fitting. Its silicone rubber shed is manufactured by an integral injection molding process, which solves the key problem of interface breakdown that affects the reliability of composite insulators. Composite insulators can be divided into line composite insulators and substation & electrical composite insulators. They can also be classified into rod suspension composite insulators, pin-type composite insulators, crossarm composite insulators, post composite insulators, wind deflection resistant composite insulators, etc.

1. High strength and light weight. Composite insulators have a high strength-to-weight ratio, i.e., a high specific strength. Their high mechanical strength stems from the excellent mechanical properties of the FRP core rod. At present, the tensile strength of the widely adopted FRP pultruded rod can reach more than 1000MPa, while the density of the core rod is only about 2g/cm³, resulting in an extremely high specific strength, approximately 5 to 10 times that of high-quality carbon steel. At the same voltage class, the weight of a composite insulator is only 1/7 to 1/10 of that of a porcelain insulator.

2. High wet flashover and pollution flashover voltage. The hydrophobicity of the low-energy surface of organic composite materials is the main reason for the excellent wet and pollution resistance of composite insulators. In environments such as heavy fog, light rain and dew, dirt is not easy to adhere to the surface of composite insulators; even if dirt adheres, it is easily washed away without affecting the insulating performance.