Effect of Composite Insulator Sealing Performance on Its Operation (Part 1)

Compared with the porcelain and glass insulators used in the traditional overhead lines, the composite insulators are lighter in weight (about 1/10 of the porcelain and glass insulators). Small in size (about 1/2 of that of porcelain and glass insulators); High strength, strong pollution resistance, zero - test, high lightning resistance; Cleaning operation and maintenance of many advantages, for the safe operation of power lines to provide a new means.

With the deepening of the understanding of composite insulator, composite insulator manufacturing technology unceasing development, the accumulation of operating experience, the composite insulator has a large area to cover large areas of 35 ~ 110 kV power transmission lines, products not only have a composite bar suspension insulator, composite cross arm and insulator, composite insulator on about tens of thousands of hits, has become the main body of transmission line insulator, about the use of line insulator is about eighty percent.

More than 20 years of operation experience shows that the probability of accidents of composite insulators in operation is only 1/3- 1/5 of that of similar porcelain insulators and 1/2- 1/4 of that of glass insulators. Nevertheless, a comprehensive understanding and analysis of the types and causes of accidents in the operation of composite insulators are necessary to further improve the safety and reliability of power lines and improve the product quality of composite insulators.

Composite insulator structure, manufacturing process, and materials have a great influence on its safe operation. Especially, the sealing structure is particularly prominent for the safe operation of the circuit. It is necessary for the operating units to continuously summarize the operating experience and discuss the influence of composite insulator structure on the operation, so as to further improve the understanding of the safety and reliability of power lines using composite insulator and promote the manufacturers to improve the manufacturing quality of composite insulator.

Glass Insulator

1. Structural characteristics of composite insulator

The composite insulator is mainly composed of three parts: mandrel, umbrella skirt, sheath, and fittings. The mandrel is mainly subjected to mechanical load and internal insulation.Umbrella skirt and sheath mainly bear the role of external insulation, usually using high temperature vulcanized silicone rubber material; Metal fittings, usually made of high-strength steel, are used to connect wires to poles and towers.

1.1 composite insulator umbrella skirt and sheath structure

At present, there are two types of umbrella skirt and sheath structures with composite insulators: one is injected, one is squeezed, and one is molded.

1) process structure of a single umbrella skirt suit after extruding or molding the sheath

The process is characterized by using a press or a vulcanizing press to directly squeeze the sheath or mold it onto the mandrel, and then a single umbrella skirt

By wearing umbrella equipment to complete the umbrella skirt and sheath, umbrella skirt, and umbrella skirt bonding.This kind of forming process is more flexible, can adjust the product structure height, creepage distance, umbrella skirt shape according to the user's requirements.The disadvantage is that there are more adhesive interfaces, adhesive quality is guaranteed by production operators, adhesive interface aging problem is yet to be observed, and the adhesive directly and the atmospheric environment, easy to cause the operation of adhesive aging, interface cracking and other undesirable phenomena.There have been reports of composite insulator interface deterioration at home and abroad which caused the insulator to quiet operation.