Analysis of a Practical Study for Under-Ground Cable Faults Causes

The underground cables are widely used for the transmission and distribution of the electrical energy over a wide range of voltages due to their merits. On the other hand, there are limitations for using the underground cables because the fault location is very difficult and consuming long time to be detected. In order to achieve a reliable operation of the electrical network and minimize the rate of the cable faults, accurate and effective fault causes analysis has to be carried out as we aim to prevent faults from happening rather than to restore the system after fault occurrence. This paper discussed the different underground cable faults and their causes through the analysis of a practical statistical study carried out for Dokky underground cable distribution networks in the Egyptian ministry of electricity to show the rate of occurrence of the different cable fault types during the previous twelve years, a practical study results were statistically analyzed and correlated to the cable faults causes analysis. It is noted that the underground cable faults are mainly due to cable insulation failure or joint insulation failure as a direct result of different partial discharge forms inside the cable or the joint.