In the process of injection molding of the epoxy insulator on EMU roof, there will be two closing joints on the surface of the umbrella skirt along the vertical direction, the convex edges will distort the electric field near it. In this paper, the influence of the closing joint on the flashover path of the epoxy insulator on EMU roof under wet conditions was studied. Through the spray flashover test, the flashover probability between the closing joint and other parts of the umbrella skirt was compared, the motion characteristics of water droplets on the surface of the epoxy resin umbrella skirt were observed, and the effects of the closing joint on the formation of water band, electric field intensity, and current density distribution were analyzed by simulation. The results show that the flashover channel is easily form at the closing joint, and under the action of electric field, the water band near the closing joint will stretch or even bridge the adjacent skirt. The current density of water band at the closing joint of high voltage end umbrella skirt is more than one time higher than that at other parts of the umbrella skirt. The water band bridging skirt will distort the local electric field, decrease the creepage distance and increase the voltage value borne by the unit creepage distance.
| 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 |