Internal water seepage is one of the common faults of cable. The accurate detection, identification, and location of internal water seepage defect in cable play a vital role in improving power safety and stability. On the basis of time-domain reflection technology (TDR) theory, the effects of injection pulse frequency and amplitude attenuation on the effective positioning distance of TDR were analyzed by simulation. The characteristic waveforms of different impedance points were obtained, the resolution method of water seepage defect waveforms was summarized, and the effect of complex reflection wave on the positioning accuracy was studied. The results show that the TDR technology can detect the water seepage defect in cable, and the effective detection distance is about 3.76 km. Different types of defects will return different characteristic waveforms, and when the degree of water seepage is different, the waveform amplitude and wave tail oscillation will also change.
| 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 |