Effect of Composite Insulator Sealing Performance on Its Operation (Part 3)

 1.3 Composite Insulators end seal structure

According to the anatomical analysis of the sealing structure of the end of the composite insulator running on the transmission line, the domestic composite insulator.

There are two kinds, one is to use room temperature vulcanized silicone rubber for end sealing, and the other is to use high temperature vulcanized silicone rubber end sealing and encapsulation technology. Long-term operating experience shows that the seal at the end of the composite insulator is the place where the electric field strength is high and the surface erosion is most likely to occur. It has been reported at home and abroad that products of this structure have cracked at the end seals after running for several years. The core rod has "brittle fracture". This "brittle fracture" is the core rod fracture of the composite insulator during operation and even caused The phenomenon of the wire falling to the ground. And in all known cases of composite insulator brittle fracture, mostly due to poor sealing performance of the composite insulator end. The core rod of the composite insulator is exposed to the surrounding air. There are various concentrations of acids in the atmosphere, and the surface of the composite insulator in humid air is electrically discharged; even nitric acid can be produced; the end of the composite insulator is sealed and cracked, and the core rod occurs. Brittle. " In order to prevent the occurrence of brittle fracture of composite insulators, we should start from two aspects at the same time. The first is to improve the moisture and acid resistance of the mandrel. The most important thing is to improve the sealing performance of the composite insulator.

Improving the sealing performance of a composite insulator is very important to prevent the composite insulator from brittle fracture. Strengthen the spindle/insulator pin sealing, its purpose is to most effectively prevent mandrel is exposed to air. Generally used sealants are mostly made of room temperature vulcanized silicone rubber, and the composite insulator vulcanized silicone rubber formed under high temperature and high pressure, the molding process is also a big difference, especially the performance of resistance to electric leakage trace, there is a world of difference. Vulcanized silicone rubber formed under high temperature and high pressure can reach the level of resistance to leakage marks above TMA4.5, while the room temperature vulcanized silicone rubber used for sealing cannot even reach tma 2.5. And in the metal parts and the outer sheath joint of the sealing interface, especially in the live end, and exactly is the highest electric field strength so that the sealant due to electricity suffered damage. Room temperature vulcanized silicone rubber climate aging resistance than high-temperature vulcanization silicone rubber obviously, this is best illustrated on insulator domestic standard IEC 1109 changes, including new test content, is insulator sealing performance test, which fully shows the insulator of the seal was damaged has to influence to the safe operation of the electric power line, ensure the sealing performance of the composite insulator is as a basic requirement for composite insulator was proposed. The most effective way to improve the end seal performance is to use high temperature vulcanized silicone rubber, in high temperature and high pressure, a whole pressure injection with a seal ring or seal groove on the metal, to avoid moisture and acid fog erosion, to ensure the end seal structure is reliable.

Spindle/Insulator Pin

Ways to improve the sealing performance of composite insulator

In summary, there are two main points of composite insulator seal structure at the present stage:

1) umbrella skirt and umbrella skirt.

2) end seal. Solution is to use high-temperature vulcanization silicone rubber, under high temperature and high pressure, a hole injection on installed hardware core rod, the manufacturing process is not only an umbrella skirt and umbrella skirt or suite no interface sealing problems, but also avoid the insulator pin spindle hardware use sealant to seal on both ends.

3. Strengthen the monitoring of composite insulator in operation

Based on the current understanding of composite insulator technology, combined with years of operation experience and basic research on operation characteristics

The power industry introduced DL/T 864-2004. It provides for the use conditions, test methods, and determination criteria of composite insulators, as well as for the installation, operation, maintenance, and monitoring.