The interface charge characteristics of oil-paper insulation under DC voltage is a huge challenge in the design of the insulation structure of converter transformers. The traditional resistance-capacitance (RC) model only considers the interface polarization charges due to the different dielectric constants and electrical conductivity of oil and paper materials, ignoring other forms of charges and their effects on the space electric field. In this paper, based on Kerr electro-optic effect, a non-contact, real-time measurement platform for space electric field characteristics in oil of oil-paper insulation was built. Aimed at the composite insulation structure consist of transformer oil-electrical insulation paper and transformer oil-transformer paperboard, the space electric field characteristics in the oil under DC voltage with different polarity and different amlitude were obtained. The difference between the total interface charge density and the polarization charge density calculated by the RC model was analyzed. The results show that when the electric field intensity in the oil is low, the total interface charge is dominated by polarization charges. With the increase of the electri field intensity in the oil, the difference between the total interface charge density and the polarization charge density calsulated by RC model increases gradually, indicat other forms of charge accumulates and its proportion in total charge increases gradually, the effect of it on the electric field increases gradually.
| 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 |