Analysis and verification of signal propagation as method for temperature monitoring of underground power cables

Underground power cables are increasingly becoming a bottleneck in the medium-voltage grid due to congestion. Limitations arise from lack of knowledge on their thermal state. This paper investigates for two commonly applied cable types, PILC and XLPE, how signal propagation velocity can be exploited as means monitoring. To this end, transit time signals sent along is interpreted terms temperature dependency insulation permittivity. The sensitivity verified by laboratory field tests. Shifts waveforms distinguished with resolution down 1 °C, but uncertainties parameters hamper direct conversion characteristics an absolute scale. Instead, changes need calibrated respect reference at known temperature. Parameter then only relative shift accuracy below 5 °C obtained. method demonstrated multi-conductor exhibiting distinct modes.