Ricerc@Sapienza

A 3D thermal model of underground power cable is presented in this paper. A detailed representation of the cable and its joints, the laying condition, the soil and the heat exchanges between soil upper surface and air, considering different weather conditions, is given. The model solves the thermal problem by means of an equivalent electric circuit and has been validated against field measurements, showing its applicability both for steady state and transient studies.

The analysis of the thermal stress of underground MV power cable joints under different environmental conditions, both in normal operation and during faults, is crucial to assess any correlation between the occurrence of overheatings and the anomalous increase of failures (two to three times compared to previous years) which have been observed in the Italian distribution network during summer 2015 (the hottest year ever since 1880).