Influence of Temperature on Wave Propagation in Low-Voltage Distribution Cables

Wave propagation in power cables depends on temperature. This paper explores its modeling for low-voltage cables, both main and service cables. Numerical thermal modeling combined with modal analysis, based on known and measured material properties, is employed to simulate waveforms expected in time-domain reflectometry tests. Comparison with laboratory measurements on a main cable shows that the main characteristics and their temperature dependency agree. The effect on wave propagation of rapid temperature rise in the conductor of a service cable during a fault is investigated. The predicted change in propagation velocity is confirmed by a field test. The perspectives of employing temperature dependent material characteristics, in particular the dielectric permittivity, on wave propagation for diagnostic techniques are briefly discussed. By accounting for the presence of different modes, the accuracy of locating the fault by means of time-domain reflectometry can be increased.