Statistical Approach to the Insulation Coordination of Medium and High Voltage Cable Lines

Risk of failure of MV and HV (up to 150 kV) cable lines stressed by lightning and switching overvoltages has been assessed by a statistical approach. Probability density functions of overvoltages amplitude in MV and HV system are estimated and correlated with the failure probability distributions of cable lines insulated with different EPR compounds. The results of the evaluation are plotted and discussed showing the influence of cable length and type of insulation compound on the risk values.