Insulator is a special kind of insulting material, which can play an important role in overhead transmission line. In order to prevent dust and other filth from adhering on the surface of insulator, the formed conductive path is broken through by the voltage of both sides of the insulator, which is known as creepage. A zero-value insulator refers to an insulator with a potential distribution near zero or zero at both ends of the insulator. The influence of zero-value insulator or low-value insulator: the insulation of the line depends on the insulator string. Due to manufacturing defect or the influence of the outside world, the insulation of the insulator performance will continue to degrade, and when insulation resistance become lower or equal to zero, it is called low-value or zero-value insulator.
On the other hand, the common classifications of insulators are:
1. Insulator is usually divided into breakdown type insulator and non-breakdown type insulator.
2. Based on structure, we have post insulator, suspension insulator, pin type insulator, shackle insulator, starin insulator, anti-pollution type insulator and bushing insulator.
3. Based on different situations, we have line insulator and power station and apparatus insulator. Breakdown type insulators used for line are pin type, shackle type and suspension type, while non-breakdown type has cross arm and rod type. Breakdown type insulators used for power stations and electrical equipment are pedestal post, hollow prop and drivepipe, while non-breakdown type has post type and container porcelain jacket.
4. Insulators used in overhead transmission line are pin type insulator, shackle insulator, suspension insulator, porcelain cross-tam, rod insulator and strain insulator.
5. The commonly used insulators are ceramic insulator, glass steel insulator, composite insulator, semiconductor insulator and etc..