| Silicone rubber composite insulators has been widely used in modern power transmission lines, due to the light weight, good performance of pollution flashover, especially in the UHV transmission lines used more widely. But its aging problem inevitable as a composite, so is more concerned by researchers. Corona aging as a main form of aging of composite insulator, because the change to surface flashover characteristics, hydrophobic properties, has become a concerned problem The modern power system. Research shows that trap properties of ceramics, polyethylene and other materials to its surface flashover has great influence. Combination effects of corona aging to characteristics of the surface of high temperature vulcanized silicone rubber material. Study on flashover characteristics of samples after corona aging can be provide a new way for power grid operation.First, developed a set of small size specimen for silicone rubber surface flashover test platform. With the help of the platform, can realize small size and larger toughness material artificial flashover test and flashover voltage, flashover current and surface charge distribution characteristic test. the surface charge measurement system has been calibrated, the test shows the effectiveness of the device.Artificial accelerated corona Aging test by multi needle to plate, get more uniform silicon rubber corona aging specimens, to the aging of specimens with different stage carried out surface flashover test and thermally stimulated current test. The study analyzed the change rule of flashover characteristics change and trap characteristics in the process of aging. The test results show that the specimen surface trap level deepening, surface charge quantity increases gradually, the flashover voltage of the corresponding also declined with the longer aging time,the wet flashover voltage decreased significantly. Meanwhile, found that the surface charge has many peak appeared in the distribution of the specimen surface, control on the surface of samples found, the peak position basic appearance in the needle electrode where the sample region. Analysis combined with the changes of the specimen surface, tip area has large aging degree, deep trap level, causes the trapped charge capacity.In addition, extraction of the scene returned from two manufacturers operating in different years of the sample. Flashover performance and trap characteristics were tested and analyzed to the corresponding samples, a factory sample as time goes, insulator sample powder surface situation is serious and the organic polymer chain segment interrupted small molecules generated in large amounts, empty change material surface increased and depth, also from the beginning of the dispersion of floc gradually become the hole concentration, flashover voltage higher, trap level decreased.Finally, by means of FTIR, SEM and other methods, the Micro chemical structure and microstructure changes be analyzed to artificial accelerated aging and the corona of on-site samples. Explore the trap characteristics of silicone rubber material influence on the flashover characteristics. The results showed that the characteristic peak of FTIR silicone rubber surface of the specimen decreases gradually, and may disappear, at the same time, a small new characteristic peak appeared, with the increase of corona aging time, which can explain the corona aging interrupt macromolecular characteristic bond of silicon rubber specimen surface. At the same time there is the formation of key features of small short, observation on the surface morphology of the sample after aging precipitation can see black or even white matter can illustrate this point. In addition, according to the SEM test analysis, the surface of the sample gradual emergence of floc and crack, hole can be used to characterize the trap phenomenon with the deepening of the aging. And through the auxiliary tests can also explain why the trap levels increase. Analysis of the above based testing can draw, the corona aging will have an impact on the surface structure of HTV specimen, with the increase of the aging time trap level deepening, thus surface charge gradually increase, abnormal local field intensity of specimen, ultimate impact of flashover voltage magnitude, make the flashover voltage has a trend of decline. Trap increased, trap energy level increases,the specimen surface is easy to moisture absorption,cause the wet flashover voltage decreased significantly. |
PDF Full Text Request