Views:78 Author:Site Editor Publish Time: 2020-03-20 Origin:Site
Insulators are special insulation controls that can play an important role in overhead transmission lines. There are many types of insulators with different shapes. Although the structure and appearance of different types of insulators are quite different, they are composed of two major parts, namely insulating part and connecting hardware.
According to different installation methods, insulators can be divided into suspension insulators and post insulators; according to the different insulation materials used, they can be divided into porcelain insulators, glass insulators and composite insulators; according to different voltage levels, they can be divided into for low-voltage insulators and high-voltage insulators.
Suspension insulators are widely used for insulation and mechanical fixing of soft buses in high-voltage overhead transmission lines and power plants and substations.
In the suspension insulator, it can be divided into a disc type suspension insulator and rod type suspension insulator. Disc type suspension insulator is the most widely used insulator for transmission lines. Rod type suspension insulators have been widely used in Germany and other countries.
Post insulators are mainly used for insulation and mechanical fixing of bus bars and electrical equipment in power plants and substations.
In addition, post insulators are often used as part of electrical equipment such as disconnecting switch and circuit breaker. In the post insulator, it can be divided into pin post insulators and rod post insulators. Pin type insulators are mostly used in low-voltage distribution lines and communication lines, and rod type insulators are mostly used in high-voltage substations.
Porcelain insulators are made of electrical ceramics. Electric ceramics are baked from quartz, feldspar and clay. The surface of porcelain parts of porcelain insulators is usually covered with enamel to improve its mechanical strength, waterproof infiltration, and increase surface smoothness. Among various types of insulators, porcelain insulators are most commonly used.
Glass insulators are made of tempered glass. Its surface is in a state of compressive prestressing. If cracks and electrical breakdown occur, the glass insulator will rupture itself into small fragments, commonly known as "self-explosion." This feature eliminates the need for "zero" testing of glass insulators during operation.
Composite insulators are also called synthetic insulators. The insulator consists of a glass fiber resin core rod (or core tube), an insulator composed of an organic material sheath and an umbrella skirt. Its characteristics are small size, light weight, high tensile strength, and excellent anti-pollution flashover performance. But the anti-aging ability is not as good as porcelain and glass insulators. Composite insulators include: rod-shaped suspension insulators, insulating crossarms, post insulators, and hollow insulators (that is, composite bushings). Composite bushings can replace a variety of porcelain bushings used in power equipment, such as transformers, arresters, circuit breakers, capacitor bushings, and cable terminations. Compared with porcelain sleeves, in addition to its advantages of high mechanical strength, light weight and small dimensional tolerances, it can also avoid damage caused by blasting.
Low-voltage insulators refer to insulators used in low-voltage power distribution lines and communication lines. High-voltage insulators refer to insulators used in high-voltage and ultra-high-voltage overhead transmission lines and substations. In order to meet the requirements of different voltage levels, different numbers of single (piece) insulators of the same type are usually used to form insulator strings or multi-section insulator post.