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The Main Problems of Composite Insulators In Operation (Part 1)

Pulished on Apr. 02, 2020

1. Overall operation

There are more and more composite insulators used in ultra-high-voltage lines. Most of the composite insulators operating in polluted areas and on DC lines have shown excellent performance. However, with the sharp increase in the use of composite insulators, the Increasing cases of network and damage are also increasing. The causes of composite insulators  on-site damage basically include: mechanical damage, brittle fracture, core rod breakage caused by factors such as typhoons, etc. The consequences of this type of accident are serious and may cause malignant power grids. Accidents; insulator damage, such as flashover, interface breakdown, etc. These damages mostly occur in early products, and the main reasons include improper material selection and immature technology.

Fuse Cutout

Fuse Cutout

2. Brittle fracture of mandrel

Mandrel brittle fracture has become the most serious accident that currently occurs in composite insulator. This phenomenon is particularly prominent in ultra-high-voltage lines. The so-called "brittle fracture" refers to the erosion of the mandrel glass fiber by acid. Under low load, the mandrel fiber gradually breaks, and eventually the whole mandrel breaks. One obvious feature of the brittle fracture is that the fracture is neat and smooth. The brittle fracture of the composite insulator can occur within operation, and it can also run for 8 or 9 years. After it happened.

The problems of insulators during construction, transportation, and storage have not affected the safe operation of the power grid, but their potential impact cannot be underestimated, because it cannot be ruled out that there may be some composite insulators that have been damaged due to construction and improper transportation. Some of the composite insulators that are brittlely broken are due to construction damage, so it is necessary to further standardize the transportation, storage and construction measures of the composite insulators.

4. Interface breakdown problem

Interface breakdown composite insulators account for 2/3 of the total number of electrical damaged composite insulators. In the early days, this phenomenon mostly occurred in the case of lightning strikes, especially suspension products and 110kV cross-arm products that used potting and extrusion processes. In recent years The composite insulators extruded and integrally injection-molded have also experienced interface breakdown many times.

Interface breakdown of composite insulators is usually caused by improper use of coupling agents or defects in the manufacturing process, which results in partial bonding failures at the interface, which makes it easy to cause discharge due to concentrated field strength. Caused by. At present, many domestic manufacturers have adopted corresponding control measures to avoid the occurrence of such defects, whether it is using squeezed umbrellas or integrated injection processes, such as ensuring the bonding strength of the interface to greatly reduce the possibility of interface breakdown. Sex, etc.