PD inception conditions and PD pattern of defects in PILC

A new medium voltage paper-insulated lead cable (PILC) network represents a large investment, and it is from the economic point of view essential to extend the life time of the medium voltage power cables as much as possible. It is known that with increasing age, the number of faults will increase and the power supply quality might deteriorate. Important symptoms of this degradation process can be related to discharging local insulation imperfections or defects which may occur in particular cable sections or cable accessories: joints and terminations. The PILC section may consist of species of different insulation types and multiple defects may occur at the same time. As a result complex partial discharge (PD) pictures may be measured representing the PD information of all these particular elements. In this study we look at the typical PILC insulation related PD induced dielectric failure processes from the physical point of view