To study the ablation mechanism of water-blocking buffer layer in high-voltage cable and reveal its critical conditions, the dielectric performance parameters of water-blocking buffer layer material with different water contents were measured. A three-dimensional non-axisymmetric corrugated aluminum sheath structure cable geometric model was constructed based on gravity effects to conduct electro-thermal-flow multi-physics field coupled finite element simulation. Experimental verification was conducted using a constant current simulated ablation test system, and the voltage and temperature variations during the ablation process were monitored in real-time. The results show that poor contact and moisture are necessary conditions for ablation. When the aluminum sheath is poorly contacted with the buffer layer, electric field concentration occurs near the gaps at the well-contacted positions, and partial discharge can be triggered when the moisture content reaches 5%. In well-contacted areas of buffer layer, capacitive current concentration causes localized temperature rise, and the local temperature would reach the ablation initiation threshold at the water content of 25%. According to the experimental results, ablation only occurs when the aluminum electrode is poorly contacted with the buffer layer, while only electrochemical corrosion is observed under good contact conditions. Electrochemical corrosion initially produces high-resistance white powder, followed by partial discharge, which makes the voltage and temperature rise steadily. With the occurrence of partial discharge, the voltage can reach 147 V, and the temperature can reach 187.8℃, causing partial melting of polyester fibers in the buffer layer, further leading to current concentration, and ultimately causing thermal breakdown of the water-blocking buffer layer material.
| 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 |