Insulators used on transmission lines can be divided into two categories: disk suspension type and rod suspension type according to the structural form, while according to the classification of dielectric materials, there are three types: disk suspension porcelain insulator, disk suspension glass insulator and organic synthetic insulator
The electric porcelain of disc-shaped suspension porcelain insulator is a porcelain piece made of quartz sand, clay, feldspar and other raw materials through ball milling, pulping, mud refining, forming, glazing and sintering. It is bonded with steel cap and steel foot by high-grade cement to form cap foot disc-shaped suspension porcelain insulator. The steel cap and steel foot bear mechanical tension, the porcelain parts mainly bear pressure, and the neck of the porcelain parts is thin, which is also the area where the electric field intensity is concentrated. When there are micro pores and other defects in the neck of porcelain parts, or cracks appear in operation, it is possible to break down the porcelain parts and produce zero value insulators. Therefore, this kind of insulator is a breakdown type insulator. The glass parts, steel caps and steel feet of tempered glass insulators are installed with high-grade cement to form cap foot type disk suspension tempered glass insulators. Its structure and shape are very close to that of porcelain insulator. When the glass parts in operation are deteriorated due to the comprehensive action of long-term mechanical force and electric field, the umbrella disc of tempered glass body will be broken, that is, "self explosion". The most remarkable feature of toughened glass insulator is that it will self explode when there are inferior insulators in toughened glass insulator, which eliminates the complicated procedure that insulators must be tested one by one. The outer end of the insulator is made of a composite silicon rubber core rod, which is formed by an epoxy resin, and the outer end of the insulator is connected with the umbrella core rod. The core rod is formed by an epoxy resin, and the outer end of the insulator is formed into a composite umbrella. The connection modes of mandrel and end fittings mainly include external wedge type, internal wedge type, internal and external wedge combined type, mandrel rib glue type and crimping type. Due to its relatively simple manufacturing equipment and manufacturing process, the quality of composite insulator products is relatively light, and all are easy to operate, which is very favored by the power department.
