To investigate the effecting mechanism of shallow traps on surface charge and surface flashover characteristics of epoxy/glass fiber composites under AC/DC superimposed voltage, this paper employed ozone surface treatment to regulate the trap parameters of composites, and systematically studied the change laws of surface conductivity, surface charge distribution, and flashover voltage of the composites with different treatment time. The results show that ozone treatment can significantly reduces the shallow trap energy levels of composites (to as low as 0.85 eV) and increases the shallow trap density (up to 2.02×1020 eV-1m-3), thereby enhancing the surface conductivity and effectively suppressing surface charge accumulation near the high-voltage electrode. The surface flashover voltage of composites increase significantly with the extension of processing time, after 4 h of ozone exposure, the flashover voltage of the samples under DC and AC/DC superimposed voltage ratios of 1∶5, 1∶3, and 1∶1 increase by 25.02%, 23.98%, 17.60%, and 10.7%, respectively. Analysis reveals that the new shallow traps introduced by ozone treatment can enhance the flashover performance by reducing surface charge accumulation, inhibiting seed electron emission and electron avalanche processes. Especially when the AC/DC superimposed voltage ratios is no more than 1∶3, ozone treatment has a more significant effect on improving the flashover mechanism dominated by charge accumulation in solid layer.
| 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 |