TYPES OF INSULATORS

1. Suspension insulator

It is widely used in the insulation and mechanical fixing of high-voltage overhead transmission lines and soft busbars in power generation and substations. Among the suspension insulators, it can be further divided into disc suspension insulators and rod suspension insulators. Disk suspension insulators are the most widely used insulators for transmission lines. Rod-shaped suspension insulators have been widely used in Germany and other countries.

2. Pillar insulator

Mainly used for insulation and mechanical fixation of busbars and electrical equipment in power plants and substations. In addition, post insulators are often used as part of electrical equipment such as disconnectors and circuit breakers.

Among the pillar insulators, it can be further divided into pin-type pillar insulators and rod-type pillar insulators. Pin-type post insulators are mostly used for low-voltage distribution lines and communication lines, and rod-shaped post insulators are mostly used in high-voltage substations.

3. Porcelain insulators

Insulators are insulators made of electrical ceramics. Electrical ceramics are baked from quartz, feldspar and clay. The surface of the porcelain piece of the porcelain insulator is usually covered with enamel to improve its mechanical strength, waterproof and infiltrate, and increase the surface smoothness. Among all types of insulators, porcelain insulators are the most commonly used.

4. Glass insulators

Insulators Insulators made of tempered glass. Its surface is in a state of compressive prestress, such as cracks and electrical breakdown, the glass insulator will break into small pieces by itself, commonly known as “self-explosion”. This feature eliminates the need for “zero value” detection of glass insulators during operation.

5. Composite insulator

Also called synthetic insulator. The insulating part is an insulator composed of a glass fiber resin core rod, an organic material sheath and an umbrella skirt. It is characterized by small size, light weight, high tensile strength and excellent anti-fouling flashover performance. However, the anti-aging ability is not as good as that of porcelain and glass insulators.

Composite insulators include: rod-shaped suspension insulators, insulating cross arms, post insulators and hollow insulators. Composite bushings can replace porcelain bushings used in a variety of electrical equipment, such as transformers, arresters, circuit breakers, capacitive bushings and cable terminations. Compared with the porcelain sleeve, it not only has the advantages of high mechanical strength, light weight and small dimensional tolerance, but also can avoid the damage caused by blasting.

6. Low-voltage insulators and high-voltage insulators

Low-voltage insulators refer to insulators used for low-voltage distribution lines and communication lines. High-voltage insulators refer to insulators used for high-voltage, ultra-high-voltage overhead transmission lines and substations. In order to meet the needs of different voltage levels, different numbers of single insulators of the same type are usually used to form insulator strings or multi-section insulating struts.

7. Anti-pollution insulator

The main measure is to increase or enlarge the shed or rib of the insulator to increase the creepage distance of the insulator to improve the electrical strength of the insulator in a dirty state. At the same time, the structure and shape of the shed is also changed to reduce the natural accumulation of pollution on the surface to improve the anti-pollution flashover performance of the insulator.

The creepage ratio of pollution-resistant insulators is generally 20% to 30% higher than that of ordinary insulators, or even more. The pollution-resistant insulators in the shape of double-layer umbrellas are used in areas with frequent pollution flashovers in China’s power grid. Such insulators have strong self-cleaning ability and are easy to clean manually.

8. DC insulator

Mainly refers to disc insulators used in DC transmission. DC insulators generally have longer creepage distances than AC pollution-resistant insulators, and their insulators have higher volume resistivity, and their connecting hardware should be equipped with sacrificial electrodes that prevent electrolytic corrosion.