Some Knowledge of Composite Insulator

July 25,2022

If composite insulators are to be used more widely in China, it is necessary to break through people's understanding that they are mostly used to prevent pollution flashover and to shake the dominant position of traditional porcelain and glass insulators. To achieve this goal, we need to pay attention to the following issues and continue to conduct more in-depth research.

 

composite insulator

 

Selection of mechanical strength

 

The most prominent feature of composite insulator mandrel is high strength and high specific strength. Its tensile strength can reach 7000mpa, and its specific strength is 5 times that of high-quality carbon steel. Some regions and departments propose to use synthetic insulators, whose mechanical strength is one level higher than that of traditional porcelain and glass insulators, such as 160kN for porcelain insulators and 210kN for synthetic insulators. When the service load is less than 40% of the rated mechanical load, the reliability of operation can be guaranteed. Therefore, composite insulators can be selected according to the method of porcelain insulators without increasing the mechanical load value. The measurement of mandrel load deflection shows that the composite insulator has good bending resistance, good galloping resistance, and aeolian vibration resistance. When used in a tension tower, it can bear certain bending moments. How different the mechanical properties of products with different end connection structures will change in long-term operation needs further study.

 

Distance to the ground selection

 

There are two opinions at home and abroad on the selection of the specific distance between the composite insulator and the ground: one is to consider the deterioration of the hydrophobicity of the surface material, taking 1:1; Second, based on the current operating experience of various countries, the specific distance can be appropriately reduced.

 

Cleaning problems

 

At present, there is no consensus on whether the fouling of composite insulators is finally porcelain insulators. The occurrence of some pollution flashover accidents and excessive pollution accumulation of composite insulators in heavy pollution areas raises the question of whether it is necessary to clean. Due to the high pollution flashover voltage of composite insulators, even if the hydrophobicity decreases or even disappears in a short time, the pollution withstands voltage of composite insulators is also 20% higher than that of insulators. Therefore, clean areas and generally polluted areas can be exempted from cleaning. For particularly serious industrial and saline-alkali polluted areas, the method of regular replacement can be adopted. According to their own experience, when the surface hydrophobicity is significantly reduced and the salt density is too large (such as more than 0.2mg/cm2), the insulator of a high-voltage fuse can be replaced, and the replacement cycle can be determined.

 

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