Analysis of short circuit capability of copper screens in medium voltage (52 kV) cables when subjected to single phase earth faults

The overall aim of this research was to examine the mechanical and thermal behaviour of 52 kV underground transmission cables when subjected to a short circuit event. A numerical model was developed and validated which examines the heat transfer from the shield wires during such short circuit occurrences. The model generates a temperature profile for the cable at different time intervals associated with normal operation, short circuit loading and post loading phase. The model was validated against experimental results and verified using the Grid Convergence Index (GCI) method. The model determined that the cable operates to specification for loads of 7,000 Amps and that there may be some scope for increasing the short circuit load rating of these cables.