Development of a live-line partial-discharge detection method for XLPE-insulated copper wire-shielded cable using a “yoke coil”

This paper describes a new partial-discharge detection method for an XLPE-insulated copper wire-shielded cable line using a “yoke coil.” Partial discharges are measured with the yoke coil which detects the azimuthal component of the current flowing through the copper wires wound on an outer semiconducting layer with a given angle against the axial direction of the cable. The highest detection sensitivity of 2 pC has been achieved at a frequency range of 5 to 20 MHz using a 77-kV 100-mm² model cable line (200 m in length). It was confirmed that the partial discharge caused by an artificial defect has successfully been detected using the proposed method. In the PD measurement for an actual 77-kV XLPE-insulated live line, the detection sensitivity was 10 pC.