The voltage endurance coefficient n of XLPE insulation can characterize the electrical life characteristics of the insulation, and the n value can be obtained by analyzing the failure data obtained from the accelerated life test. However, the accuracy of the n value is affected by the applied field strength in the accelerated life test and the analysis method of the failure data obtained in the test. In this paper, the evaluation method of voltage endurance coefficient n was studied. The constant stress test and the step stress test were conducted on XLPE insulation samples, respectively, and a test data analysis method based on damage eigenvalues was proposed. This method established the mapping relationship between accumulated damage threshold (Dc) and n in the test through the damage matrix, and used the change of matrix rank as the selection criteria of n value. The results show that according to the proposed method, the XLPE insulation voltage endurance coefficient n2 obtained in constant stress test is 12.43 and n3 obtained in step stress test is 12.04, which compare with the XLPE insulation voltage endurance coefficient n1 of 12.83 obtained by linear fitting, the difference is only 3% and 6%. Moreover, the proposed method can save more than 75% of the test time, which verifies the effectiveness of the method.
| 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 |