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High Frequency Measurements on Medium Voltage Cables For Localisation of Degraded Regions R. Papazyan, R. Eriksson |
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Furthermore, an investigation of the influence of the cable construction is required. Such an analysis estimates the influence of external parameters on the measurements, as compared to the influence of insulation ageing. It is discovered that the cable metallic screen can significantly influence the high frequency characteristics. Both experiments and 3D numerical modelling have been used for this investigation and results are herewith presented. Additionally, TDR would detect reflections coming from insulation ageing, but it also records reflections related to geometrical irregularities along the cable length. To distinguish between the two a measurement procedure is used, based on the voltage nonlinearity of water treed insulation. TDR measurements have been performed before, after and during the application of high AC voltages. Comparison of the TDR measurements before/after and during different HV stresses is crucial for distinguishing the signals related only to insulation ageing. |
ime Domain Reflectometry (TDR) is used for localisation of transmission line discontinuities in diverse applications. Various challenges have to be addressed when applying TDR for power cables. Initially, the propagation properties of the cable are investigated using measurement methods both in the time and frequency domains for characterization up to 1.3 GHz.