Line post-type porcelain insulators can replace pin-type insulators. Pin-type insulators, belonging to type B, are prone to breakdown and damage during operation. Tempered glass insulators will spontaneously break in this situation, while porcelain insulators will not. Therefore, power companies must spend considerable manpower and resources on electrical testing and preventative checks of porcelain insulators, which is economical and has certain shortcomings in terms of power supply reliability. Consequently, with the development of manufacturing technology, line (solid) post-type insulators have emerged. These insulators all have solid insulators and belong to type A insulators. Therefore, there is no need to worry about breakdown along the inside of the insulator during operation, which is a major advantage.
Porcelain insulators for power lines are classified into eight grades according to their rated lightning impulse withstand voltage: 95, 105, 125, 150, 170, 200, 250 and 325kV; four grades according to their rated bending failure load: 3, 5, 8 and 12.5kN; two types according to their installation method: vertical installation and horizontal installation; two types according to their connection method with high-voltage conductors: top binding type and top clamp type; and two types according to the connection method between the steel foot and the base: detachable type (threaded connection) and non-detachable type.
