Effect of protrusions in HVDC cables

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…They could occur because of limitations in the manufacturing of these cables or mistakes done while installing them. The size and shape of the protrusions should also be considered because the sharper the protrusion is for instance then a higher electrical stress would be the outcome due to a higher space charge density accumulated at the sharp area of the protrusion giving a higher stress enhancement factor which is defined as the ratio of the maximum electric field due to the protrusion and the average electric field in XLPE disregarding the protrusion [8].…”

“…Subsequently, continuous monitoring and safety procedures of the XLPE are vital to evade any malfunction occurring in the power cable [6]. One of the critical reasons for the degradation of power cables are the defects/irregularities in the insulation [1][2][3][4][5][6][7][8]. The irregularities are usually gas-filled voids and protrusions as shown in Fig.…”

“…These irregularities distort the electrical field across the insulation increasing the degree of non-uniformity of the field. Moreover, the conduction and polarization properties are impacted, and the intensity of partial discharges occurring rises, which places the HV cable in a susceptible condition [2,[8][9].…”

“…Having voids inside and outside the protrusions, and vented water trees grown from protrusions is also not profoundly researched as most papers just investigate the protrusions on its own which is not always the case in practical situations. The reference [8] is on the effect of protrusions in HVDC cables and considers the effect of spherical and spheroidal protrusions on the electric field and from that determine the changes in the stress enhancement factor. Therefore, this paper attempts to build on that by considering voids inside and outside the protrusions and vented water trees grown from protrusions mentioned previously at the conductor screen which is a configuration rarely investigated although it happens in practice.…”

Influence of surface charge decay on cavity PD frequency at DC voltage

“…The defects may come from the manufacturing, installing and operation processes of equipment, typical one of which is cavity defect, e.g. a void embedded in a cross-linked polyethylene (XLPE) cable because of improper technical control in production process [1]. During a long service time of power equipment, cavity PDs will deteriorate the insulation performance of surrounding solid dielectrics, and even cause the final insulation fault.…”