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Mastering the distribution pattern of surface charges during DC pre-flashover is essential for clarifying the intrinsic mechanism of charge-induced flashover. This paper investigated the surface charge distribution characteristics of epoxy resin at DC pre-flashover moment and their influences on flashover voltage magnitude based on a plate-type insulation structure. Under two testing conditions—with and without pre-deposited charges on specimen surfaces—the dynamic distribution of surface charges was captured during the process of applied voltage escalation leading to flashover. By introducing SiC-epoxy composite coatings to modify specimen surface states, the dominant charge accumulation patterns during flashover triggering and the charge accumulation modes preceding flashover occurrence were comparatively analyzed. The results show that homopolar charge accumulation predominates on specimen surfaces during voltage escalation toward flashover. The charge accumulation mode exhibites a transition phenomenon shifting from the micro-charge zone to the charge surge zone during flashover triggering. Immediately before flashover, homopolar charges nearly coveres the entire specimen surface, while the pre-deposited charges primarily influence the flashover voltage magnitude by altering the homopolar charge accumulation quantity at the pre-flashover moment.
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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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