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The intermediate joint of power cables is a key node in power transmission and distribution system, the interface pressure of the joint directly impacts its insulation performance and current-carrying capacity. However, a technical bottleneck remains in the non-destructive quantitative measurement of interface pressure in multi-layer heterogeneous materials. This paper proposed a non-destructive testing method for interface pressure in 10 kV cold-shrinkable cable accessories based on ultrasonic nonlinear effects. First, samples with different interface pressures were prepared, and reference values were obtained using built-in sensors. Then, a mechanical pressurization device was designed to expand the experimental pressure range. Based on a nonlinear ultrasonic testing platform, time-frequency domain characteristics of the echo signals from three types of composite interfaces of the 10 kV cold-shrinkable cable joint were analyzed. Finally, a quantitative mapping model between interface pressure and the nonlinear ultrasonic coefficient was established and verified. The results show that in the interface pressure range of 0-0.40 MPa, the amplitudes of the fundamental wave and the second harmonic wave generally decrease with increasing interface pressure, while the nonlinear coefficient first increases and then decreases. The use of the pressurization module improves the accuracy of the pressure measurement results. The application of silicone grease on the XLPE interface can fill the microscopic air gaps and weaken the nonlinear effect in that area, but has little influence on the nonlinear behavior of the interface and does not affect the pressure measurement results. It is demonstrated that the relative nonlinear coefficient can serve as an effective characterization index for the interface pressure of cold-shrinkable cable accessories, providing a reliable non-destructive testing technical path for cable operation condition monitoring and life assessment.
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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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