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Oil-paper insulation is the main insulation material for oil-immersed power equipment, and its ageing under long-term complex working conditions will seriously affect the use safety of equipment. Therefore, the accurate evaluation of its insulation status is crucial. Multiple sets of oil-paper insulation models with different degrees of ageing were prepared in this paper, and wide temperature-wide frequency dielectric response tests at different test excitation amplitudes were conducted. Characteristic parameters characterized the ageing of oil-paper insulation was extracted on the basis of Disado-Hill relaxation model. The test results show that as the ageing of oil-paper insulation increases, the full frequency range loss factor curves show two characteristic frequency ranges, which are respectively related to the material conductivity characteristics, turning polarization and interface polarization process. According to the fitting calculation results, it is found that after ageing of the oil-paper insulation, the cellulose structure is damaged, and the number of impurity ions in the dielectric increases, which is manifested at the micro level as enhancing the inter cluster motion within the dielectric and weakening the intra cluster motion. Therefore, the characteristic frequency points in the model move towards higher frequencies. Meanwhile, to accurately obtain the ageing state of oil-paper insulation, a quantitative characterization relationship between model characteristic parameters and insulation ageing was constructed by eliminating the influence of test temperature and excitation amplitude. The research results provide theoretical support for the evaluation method of insulation ageing state of oil-immersed power equipment based on frequency domain dielectric response on-site detection technology.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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