Insulator
An insulator is a device which is mounted between a conductor or conductors of different potentials and a grounding member and capable of withstanding voltage and mechanical stress. Insulators come in a wide variety of shapes. Although the structure and shape of different types of insulators differ considerably, they are composed of two major parts: insulating parts and end fittings.
The insulator is a special insulation control that can play an important role on overhead transmission lines. In the early years, insulators were mostly used for utility poles, and slowly developed into a lot of disc-shaped insulators used for high-voltage wire connecting towers. This is to increase the creepage distance. They are usually made of glass, ceramic or silicone rubber. The insulator should not fail due to various electromechanical stresses caused by changes in the environment and electrical load conditions, otherwise the insulator will not have a significant effect, which will impair the use and operating life of the entire line.
The insulators can be divided into suspension insulators and post insulators according to the installation method; porcelain, glass and composite (also known as synthetic insulators) according to the insulation materials; low-voltage insulators and high-voltage insulators according to the voltage levels used; stain-resistant insulators used in contaminated areas according to the environmental conditions used; DC insulators according to the voltage types used; and insulators for various special purposes, such as insulation cross-bearing, semiconductor glazed insulators and tensile insulators for power distribution, bobbin insulators and wiring insulators. In addition, depending on the possibility of breakdown of the insulation, it can be divided into two types: Type A, which is the non-breakable insulator, and Type B, which is the breakable insulator.
The main function of the insulator is to achieve electrical insulation and mechanical fixation, for which there are various requirements for electrical and mechanical properties. For example, under the specified operating voltage, lightning overvoltage and internal overvoltage, no breakdown or flash envelope along the surface will occur; under the specified long-term and short-term mechanical load, no damage and damage will occur; under the specified machine, electrical load and various environmental conditions, after long-term operation, no obvious deterioration will occur; under the operating voltage, the fittings of the insulator will not produce obvious corona discharge phenomenon, so as not to interfere with radio or television reception. Because the insulator is a widely used device, interchangeability of its connecting fittings is also required. In addition, the technical standards for insulators require various electrical, mechanical, physical and environmental conditions to be tested for performance and quality, depending on the type and conditions of use.