Study On The Vacuum Potting Technology For High-Voltage Insulators In Space Application

High-voltage insulators for space application is the key components affecting the reliability of power transmission of the travelling wave tube amplifier (TWTA). Statistical analysis shows that 80% of the faults occurred in the thermal vacuum tests and 70% of these vacuum test faults caused by bubble defections during vacuum potting of the high-voltage insulators in China. The vacuum potting technology for high-voltage insulators has been one of the bottlenecks that block the development and application of the space TWTA in our country. Therefore, a systematic study is carried out in this dissertation on the formation mechanism of bubble defection, the process technology and the equipments of vaccum potting process, to make perfect high-voltage insulators and to meet the military standards. The contents and the main results are summarized as below.1. Based on the analysis of the bubble formation mechanism in the vacuum potting, bubble growth model in vacuum potting for high-voltage insulators is constructed, and vacuum parameter is predicted for the potting process. In order to prevent the high-voltage insulators from the bubble defections, the bubble inhibition model is constructed, bubble inhibition mechanism during impregnation process in vaccum is analysed and the impregnate pressure is predicted for the potting process.2. With CCD camera detection, the bubble formation in vaccum potting process for high-voltage insulators is analysed. Through analysing the internal electric field of the high-voltage insulators, the partial discharge (PD) detection method is established for testing of the bubble defection in high-voltage insulators.3. Potting resin material for high-voltage insulators is determined by analysing and testing of mechanical properties, thermal properties and electrical performance of candidate resins. Via analysing the factors and their functions of potting molds for the vaccum potting process, design criteria for accuracy and air exhausting of the mold are put forward, and the potting mold is further more developed. With potting process test verification, the vaccum potting process parameters, such as the metering ratio, mixing degree, degassing vacuum and potting vacuum, impregnation pressure etc., are determined. And the technical specifications are proposed.4. Based on the process reqirement analysis for vacuum potting of high-voltage insulators, the mockup of the vaccum potting system for high-voltage insulators is developed by integrating the metering, mixing, vacuum degassing and control techonolies. The mockup was validated via system function testing to meet the design requirement. The sample potted by the mockup passed the destructive physical analysis (DPA) test, X-ray test and PD test and can fulfill the production of the high-voltage insulators.The priciples and results of the dissertation can also be applied to the potting of other electrical insulators.