Due to the low thermal conductivity of XLPE main insulation and low temperature of seawater, it is easy to form a large temperature gradient in submarine cable insulation. The formation of temperature gradient will cause a radial difference in the aggregation and dielectric properties of XLPE, so as to influence the electrical treeing deterioration process. In order to study the electrical tree characteristics of XLPE under temperature gradient, a temperature gradient electrical tree experimental platform in the range of 10-90℃ was built, and the initiation and growth characteristics of electrical tree under different temperature gradient were measured. The results show that the changes of needle tip electric field and XLPE aggregation under different temperature gradient will affect the initial voltage of electrical tree. With the increase of temperature gradient, the main structure of electrical trees presents gradual change characteristics of rattan-branch tree, bush-rattan tree, and bush tree.
| 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 |