Single end self-clearing transient fault location for preventive maintenance of power cable systems

Self-clearing transient faults can be considered as precursor of imminent failure of power cables. They exist during a very short duration (few ms) and cannot be detected by conventional protection relay. However, they weaken dielectric, causing other transient faults in the future with increasing frequency of occurrence until final insulation breakdown. Thus, imminent failures can be avoided by preventive maintenance if these transient faults are correctly detected and located. This paper presents a method for locating single phase to ground transient faults based on current and voltage measurements at one end of a power cable. Both distance to fault and fault resistance can be estimated by a least square fitting algorithm. Cable capacitances are also considered in our model. The proposed fault locating algorithm has been validated with a small distribution feeder, with two values of grounding impedance.