LOCATION OF PARTIAL DISCHARGES IN SHIELDED CABLES IN THE PRESENCE OF HIGH NOISE

This paper presents updated information on a partial discharge location system intended to pinpoint the location of defects and/or faults on a shielded buried underground cable. It is based on the principle of reflectometry. Its salient characteristics include the following two features: (a) ability to pinpoint the location of a partial discharge source not only along the cable length, but also along the surface of the trench where it is buried; (b) ability to operate in a high noise environment. Recent field and laboratory data obtained on noise, and techniques for its mitigation are discussed in some detail. These techniques include analog/digital notch filters for the elimination of AM broadcast noise and an adaptive digital filtering scheme which incorporates the transfer function of the cable for added accuracy.