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The operating environment of EMU is complex, under the influences of multiple factors such as electricity, heat, and high-speed airflow, the performance of insulating material for high-voltage cable terminal on the roof is an important factor affecting the safety and stability of power supply system for EMU. In this study, the thermal conductivity, glass transition temperature, and dielectric properties of typical insulating materials for cable terminal on the roof were tested and analyzed by combining experimental analysis with simulation calculation. The electric field distribution at room temperature and the temperature distribution at different ambient temperatures of the cable terminal were studied by establishing an electric-thermal coupling simulation model of the roof cable terminal. The results show that the thermal conductivity of both ethylene-propylene-diene monomer (EPDM) and epoxy resin (EP) increases with the increase of temperature, and decreases with the increase of temperature when the temperature is higher than 80℃. At room temperature, the thermal conductivity of EPDM and EP is 0.251 W/(m·K) and 0.431 W/(m·K), respectively. The dielectric constant of EPDM decreases gradually with the increase of temperature, decreasing from 3.7 at -60℃ to 3.28 at 100℃. The dielectric constant of EP increases gradually with the increase of temperature, increasing from 5.02 at -60℃ to 5.29 at 100℃, which is due to the difference of their glass transition temperature. The simulation results show that the change of electric field at the terminal of AC cable caused by temperature is small, the maximum distortion point occurs at the root of stress cone, and the electric field is 3.12 kV/mm. The secondary electric field concentrates in the main insulation of cable, and the electric field is 2.9 kV/mm.
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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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