To research the strain characteristic and its measurement method of encapsulation insulation for dry-type air-core reactor, the methods of making test model, embedding sensor and strain gauge, and calculating strain were studied. A test model was made and a test system was built, and the internal strain of encapsulation was studied during the process of reducing temperature and applying current at different low temperatures. The results show that the circumferential thermal expansion coefficient of the encapsulation insulation is less than the axial thermal expansion coefficient and there is anisotropy, which makes the circumferential strain larger than the axial strain. During the process of reducing temperature, negative strain is produced by circumferential shrinkage of the encapsulation insulation, which decreases gradually with the temperature decreasing, the decline rate gradually slows down in the same cabin temperature, and the value increases significantly with the increase of temperature decline amplitude in different cabin temperatures. The axial strain is positive when the cabin temperature is higher, which gradually changes to a negative value with the temperature decreasing, and the change law also changes from gradually increasing to gradually decreasing with the temperature decreasing. During the process of reducing temperature, the circumferential and axial strains have negative jumps many times, resulting in shrinkage micro-cracks. The strain change during process of applying current is contrast to the process of reducing temperature, with the increase of temperature, the circumferential strain increases gradually, the axial strain decreases rapidly, and neither strain jumps. By calculating the maximum thermal stress, it is further verified that the circumferential compression stress is larger than the compression strength of the epoxy glass fiber, resulting in the damage of encapsulated insulation.
| 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 |