The key power equipment with the oil-pressboard insulation winding structure is prone to appear the problem of acetylene content exceeding the standard when putting into operation, and then partial discharge and arcing phenomena are produced. Therefore, the point discharge and arcing characteristics of oil-pressboard insulation were studied under switching impulse voltage and superimposing power frequency electrical stress. The discharge and arcing characteristics of different point defects were compared and analyzed, and the influence of the superimposed phase of impulse voltage and power frequency voltage was discussed. The results show that the arcing process of the defect model containing pressboard after breakdown can divide into high-frequency re-arcing stage, stable arcing stage, and re-arcing stage before the voltage restored. Among them, the high-frequency re-arcing stage has higher arcing frequency and lower recovery voltage. Under the switching impulse voltage, the pure oil gap defect model shows multiple breakdown, and the oil-pressboard composite insulation defect model shows that the pressboard breakdown directly and the oil pressboard breakdown successively, and the defect model type affects the discharge characteristics and arcing rule. The superposition phase affects the discharge characteristics and arcing law by affecting the electrical stress magnitude.
| 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 |