Silicone rubber is the main reason for the excellent electrical properties of synthetic insulators. The main chain of silicone rubber molecules is composed of silicon-oxygen chains. According to the different molecular composition and structure, silicone rubber can be divided into many types.
The methyl vinyl silicone rubber is vulcanized by an oxide vulcanizing agent to become a solid silicone rubber with a certain shape. The main chain of the silicone rubber molecule is a chemically stable Si-O bond structure. And the organic side groups of the main chain of silicone rubber molecules have no unsaturated bonds, so in addition to excellent atmospheric aging resistance, ozone aging resistance and other characteristics similar to inorganic materials, silicone rubber also has many characteristics of organic materials.
Due to the poor mechanical properties of pure silicone rubber itself, various fillers have been added to various silicone rubber products for different purposes to modify the silicone rubber. Silicone rubber composite insulators are filled with fumed silica, aluminum hydroxide and other fillers. Appropriate addition of fillers can improve the atmospheric aging resistance, ozone aging resistance, high and low temperature resistance, mechanical properties and electrical properties of the silicone rubber material. Of course, the types and quantities of fillers added are different, and the positive and negative effects and the degree of influence are also different. The actual use of silicone rubber materials inevitably must add various fillers, so it is also called silicone rubber materials, but the performance of various silicone rubber products is not the same. The type and quantity of filler added must be obtained through a lot of experiments. Excellent aging resistance and tracking resistance are one of the key factors for silicone rubber to be used for outdoor insulation, especially in polluted areas.
Therefore, the transformation of the umbrella shape of the composite insulator can improve the electric field distribution along the surface of the glass insulator in the ice-covered state. Comparing the electric field distribution of the double-umbrella and four-umbrella insulators, it can be seen that the four-umbrella composite insulator has obvious advantages. Therefore, it is recommended to use four-umbrella composite insulators.
The large umbrella diameter and the large umbrella distance have obvious influences on the electric field distribution of the composite insulator under the same ice-covered state. decreases as the diameter increases. However, when the umbrella diameter of the composite insulator exceeds 245mm, this trend slows down. In order to improve the electrical performance of the insulator under the ice-covered state and at the same time ensure the self-cleaning of the insulator, the middle and small umbrellas of the composite insulator are protected by the large umbrella. The umbrella diameter has little effect on the potential distribution along the surface of the entire composite insulator.
The composite insulator grading ring has a certain influence on the distribution of the surface field strength under the condition of ice coating. When the lifting distance is 0-5cm, the maximum field strength of the high voltage end and the ice edge gap near the high voltage end can be well matched. , and at the same time, in order to ensure that the lifting distance of the insulator grading ring does not reduce its arc distance, thereby reducing the impact flashover voltage.
2020/05/27
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