Insulators can be divided into high voltage insulators and low voltage insulators according to the voltage used. Insulators can be divided into porcelain insulators, glass insulators and organic material (epoxy resin cast) insulators according to the manufacturing materials. Insulators can be divided into indoor insulators and outdoor insulators according to their installation locations. Insulators can be divided into 11 subcategories and 48 series according to their structure and purpose.

Classification of insulators

Insulators can be divided into high voltage insulators and low voltage insulators according to the operating voltage.

Insulators can be divided into porcelain insulators, glass insulators and organic material (epoxy resin cast) insulators according to their manufacturing materials.

Insulators can be divided into indoor insulators and outdoor insulators according to their installation locations.

Insulators can be divided into 11 categories and 48 series according to their structure and purpose.

The main purpose of insulators

1) High voltage line insulators

① Rigid insulators for high-voltage lines: including pin-type porcelain insulators, porcelain cross-arm insulators and butterfly-type porcelain insulators.

According to the structural form, the porcelain cross-arm insulators for high-voltage lines can be divided into four types: full-porcelain type, glue-mounted type, single-arm type and V-shaped; according to the installation form, they can be divided into two types: upright type and horizontal type; according to the 50% full-wave impulse flashover voltage, they can be divided into 185kV, 210kV, 280kV, 380kV, 450kV, 610kV and other levels. They are used in high-voltage overhead transmission and distribution lines, can replace pin-type and suspension insulators, and save the high-pole porcelain arm.

High-voltage line butterfly-type porcelain insulators are divided into two levels according to rated voltage: 6kV and 10kV.

It is used for the terminals of overhead power transmission and distribution lines, as insulation and fixing conductors on tension and corner poles. It is also widely used in conjunction with line suspension insulators as a component in line hardware to simplify the hardware structure.

② High-voltage line suspension insulators: including disc-shaped suspension porcelain insulators, disc-shaped suspension glass insulators, porcelain rod insulators and ground wire insulators, etc.

High-voltage line disc suspension porcelain insulators are divided into two types: ordinary type and pollution-resistant type. They are used for high-voltage and ultra-high-voltage transmission lines to suspend or tension conductors and insulate them from the tower. Suspension insulators have high electromechanical strength and can be used for various voltage levels and various strength requirements through different string groups. They are the most widely used. Ordinary types are suitable for general industrial areas. Compared with ordinary insulators, pollution-resistant types have larger creepage distances and shapes that are easy to clean in wind and rain. They are suitable for coastal areas, metallurgical powder, chemical pollution, and areas with severe industrial pollution. When pollution-resistant insulators are used in the above-mentioned areas, the size of the tower can be reduced, which has great economic value.

The uses of high-voltage line disc-shaped suspension glass insulators and high-voltage line disc-shaped suspension porcelain insulators are basically the same. Glass insulators have the characteristics of high mechanical strength, mechanical impact resistance, good cold and hot performance, long life, excellent electrical performance and lightning resistance, and when damaged during operation, the umbrella disk will automatically break, which is easy to find, greatly reducing the workload of insulation detection.

High voltage line porcelain rod insulators are used on terminal tension and corner poles of overhead power lines of 10kV and below for insulation and conductor fixation. They can replace some butterfly porcelain insulators and disc suspension porcelain insulators.

③Rod-type porcelain insulators for electrified railway contact network

2) Low voltage line insulators

① Pin-type, butterfly-type, and shaft-type porcelain insulators for low-voltage lines: Pin-type porcelain insulators for low-voltage lines are used for insulation and fixed conductors in overhead power lines below 1kV. Butterfly-type porcelain insulators for low-voltage lines are used for insulation and fixed conductors on distribution line terminals, tension poles, and corner poles. Shaft-type porcelain insulators for low-voltage lines are used for insulation and fixed conductors on distribution line terminals, tension poles, and corner poles.

② Overhead line tensioning porcelain insulators: used at the terminal corners or large-span poles of AC and DC overhead transmission and distribution lines and communication lines to balance the tension on the poles and to tighten insulation and connections.

③ Insulators for tram lines: used for insulation and tensioning conductors of tram lines or for insulation and support of conductive parts in trams and power stations.

④ Communication line pin-type porcelain insulators: used to insulate and fix conductors in overhead communication lines.

⑤ Wiring insulators: including drum insulators, porcelain plates and porcelain tubes, etc. Used for low-voltage wiring.

3) Insulators for high voltage power stations

① High-voltage indoor post insulator for power stations: used for the busbars and distribution devices of electrical equipment in indoor power stations and substations with a rated voltage of 6-35kV. As an insulating support for high-voltage conductive parts. It is generally installed at an altitude not exceeding 1000m, with an ambient temperature of -40 to 40℃, and should be used under conditions free from contamination and condensation. The specially designed plateau type can be used in areas with an altitude of 3000m and 5000m.

② Outdoor pin-type post insulator: Suitable for use as insulation and fixed conductors in the insulating parts or distribution devices of electrical appliances with an AC rated voltage of 3-220kV, an ambient temperature of -40 to +40℃ at the installation location and an altitude not exceeding 1000m.

③ Outdoor rod-type post insulator: used for high-voltage electrical appliances and high-voltage power distribution equipment, and plays the role of insulation and fixing conductors. It has largely replaced the use of outdoor pin-type post insulators.

④Pollution-proof outdoor rod-type post insulator: Suitable for medium-pollution areas with salt density within 0.1 mg/cm2, used as insulation and fixation for high-voltage electrical appliances and distribution equipment.

⑤ High-voltage wall bushing: including indoor wall bushing, outdoor wall bushing, busbar wall bushing and oil-paper capacitor wall bushing, etc.

⑥ Electrical appliance porcelain bushings: including transformer porcelain bushings, switch porcelain bushings, and transformer porcelain bushings.

Transformer porcelain bushings include two categories: bushing porcelain bushings for power transformers and test transformers, and support porcelain bushings.

Switch porcelain sleeves include high-oil circuit breaker porcelain sleeves, low-oil circuit breaker porcelain sleeves, load switch porcelain sleeves, explosion-proof switch porcelain sleeves, disconnector porcelain sleeves, air circuit breaker porcelain sleeves, etc. They are mainly used as insulation for the high-voltage lead of the switch to the ground and as a container for circuit breaker insulation and internal insulation.

Transformer porcelain bushings are used as insulating elements for current transformers and voltage transformers.