According to different purposes, line insulators can be further divided into several different types. The line insulators used for repairing overhead conductors on towers are called suspension insulators. Insulators that need to withstand wire tension at the beginning, end, turns, and other parts of the line are called tension insulators. Suspension insulators and tension insulators are both fixed on the tower arm connected to the tower post. Their structure and shape may be the same, but the difference is only the suspension method and function. Suspension insulators are vertical or V-shaped suspension, while tension insulators are horizontal suspension. The mechanical strength requirements for tension insulators are high, and multiple strings in parallel are often used. In urban areas, in order to reduce line corridors, overhead lines often use cross arm insulators, which act as both insulation and cross arm insulators. According to the insulation materials used, insulators can be divided into three categories: electric porcelain, glass, and composite insulators. Composite insulators, also known as composite insulators, are also known as organic or non ceramic insulators. Electric porcelain and glass insulators are made of inorganic materials, and porcelain insulators have a history of over 100 years of use. Glass insulators have a history of over 70 years of use, and composite insulators have a relatively short history. It was not until the 1970s that they were successfully used for external insulation in power systems. Semiconductor glazed insulator is a special form of electric porcelain insulator, which is coated with a layer of semiconductor sleeves on the surface of ordinary electric porcelain insulators. It is mainly used in polluted areas. According to the specific structure of insulators, they can be divided into two categories: line insulators and power station insulators. Line insulators are divided into suspension insulators, pin insulators, cross arm insulators, etc. Suspension insulators are also divided into disc suspension insulators and rod suspension insulators. Power station insulators can be divided into several categories, including post insulators, porcelain sleeves, and bushings. 1. Suspension insulators are divided into two categories: disc suspension insulators and rod suspension insulators. The disc suspension insulator consists of iron phase (malleable cast iron), steel foot (low-carbon steel), and porcelain parts (or tempered glass). Cement bonding is used between hardware and insulation components. The insulation components of rod suspension insulators are divided into two categories: electric porcelain and Xia Fencai 44. The advantage of rod suspension insulators is their simple structure. The insulation components are non breakdown and do not need to be tested for zero values. 2. Pin insulators are mainly used in 6-10kV distribution lines. They have a wire slot at the top and the wires can be fixed in the slot. Pin insulators are also used in 20-35kV lines. However, due to their high aging rate and large size, they have gradually been replaced by suspension insulators. 3. Cross arm insulators are mainly made of two types of materials: electric porcelain and composite materials. Electric porcelain cross arm insulators are rod shaped porcelain components that are installed on poles to support the wires. They not only serve as insulation between the wires and the ground, but also as cross arms. When the voltage level is high, the mechanical strength of the cross arm insulators is required to be high. 4. Power station post insulators are used as insulation and mechanical fixed connections between conductive bodies and grounding bodies, such as post insulators for busbars or isolation switches. It is composed of a solid porcelain column and a metal accessory on the top and bottom, which is assembled by cement adhesive. The porcelain sleeve is used as a container for internal insulation of electrical appliances, such as the porcelain sleeve of current transformers and circuit breakers. The requirements for the external insulation of porcelain sleeves are the same as those for the external insulation of pillar insulators. Both have high requirements for the structure of umbrella W. They are required to have high resistance to pollution flashover and rain flashover. Generally speaking, the external insulation of porcelain sleeves is thicker, and with the increase of the outer diameter, the pollution flashover and flashover resistance of insulators will decrease. Therefore, the electrical strength of the external insulation of porcelain sleeves is required. 6. Bushing is the insulation of the lead wire when the current carrying wire is led into the metal box or busbar of electrical equipment such as transformers or circuit breakers, and passes through the wall. Bushing is a typical insulation structure with a strong vertical dielectric surface component in the electric field. The voltage distribution on the surface is extremely uneven. The electric field at the edge of the middle flange is very concentrated, and it is easy to start corona and flashover discharge from here. The insulation material of the sleeve used to be made of electric porcelain material. In recent years, composite sleeves have emerged. Due to the strong anti pollution flashover ability of the silicone rubber material used as external insulation, the use of composite sleeves has increased rapidly. The development momentum is promising. There are higher requirements, especially for the porcelain sleeve of the current transformer. Its structural shape is thin at the top and thick at the bottom, and the umbrella skirt is more easily bridged by rainwater. The ability to withstand rain flashes is low, so sufficient attention must be given to this issue