Method for evaluating insulation performance of cable by measuring wave velocity through FDR wave crest transition
A cable insulation, 1. FDR technology, applied in the field of power cables, can solve the problems of non-destructive evaluation of cable insulation performance, large loss, etc., and achieve a highly scientific and logical effect
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Embodiment 1
[0028] Such as Figure 1-2 As shown, in step S1, as the relative dielectric constant of the insulating material increases, the attenuation coefficient of the cable will increase and the wave velocity will decrease. Corresponding to the reflection coefficient spectrum, the amplitude of the real part of the reflection coefficient will decrease and the frequency will increase. Therefore, the overall aging state of the cable insulation is evaluated by analyzing the amplitude of the reflection peak at the end of the cable in the frequency domain reflection curve and the position on the horizontal axis, and the effectiveness of the method of evaluating the overall insulation performance of the cable using frequency domain reflection technology is verified, and experimental research is carried out. In step S1, the frequency value of the real part of the reflection coefficient is directly used to evaluate the overall insulation performance of the cable, and the magnitude of the real pa...
Embodiment 2
[0036] Such as Figure 1-2 As shown, three groups of cable samples with a total length of 100m, 200m and 300m are respectively set in step S2, and the relative dielectric constants of the insulating materials in the three groups of cable samples with different lengths are set to 2.3, 3, 3.5 and 4 respectively in step S2, To simulate cables with different degrees of overall insulation aging.
[0037] In order to verify the effectiveness of using frequency domain reflection technology to evaluate the overall insulation performance of cables, simulation tests are carried out in this section. The simulation model adopts the model in Chapter 2, and three groups of cable samples with total lengths of 100m, 200m and 300m are respectively set up. Three groups of different lengths The relative dielectric constants of the insulating materials in the cable samples were set to 2.3, 3, 3.5, and 4, respectively, to simulate cables with different degrees of overall insulation aging. In this...
Embodiment 3
[0042] Such as Figure 6 As shown, in step S3, the test frequency range in frequency domain reflection is set to 150kHz-900MHz, and the number of test points is 1601.
[0043] In order to actually verify the validity of the method of evaluating the overall insulation performance of cables using frequency domain reflection technology, this section will carry out experimental research. Affected by weight and volume, it is difficult to carry out overall thermal aging experiments on longer XLPE power cables, so a 20m coaxial communication cable is used to carry out experiments. Coaxial communication cables and power cables have almost the same coaxial distribution structure. In the transmission line theory, the two are similar, so the frequency domain reflection test results are almost universal. Put the coaxial communication cable into a high-temperature drying oven for thermal aging. The thermal aging temperature is set to 100°C, and the total aging time is set to 48h. The freq...
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