Electrical tree initiation in XLPE cable insulation by application of DC and impulse voltage

Abstract

Electrical tree initiation behavior of XLPE cable insulation was investigated by application of DC voltage, impulse voltage, repetitive DC voltage, and impulse voltage after DC prestressing. Treeing test samples are made of XLPE specimens with a pin-plane electrode system. The needle inserted has a tip radius of 5 μm and a pinpoint angle of 30 °, and the pin-plane distance is 2 mm. No trees appeared when DC voltage up to 70 kV or -60 kV was applied on the samples continuously or repetitively. Impulse voltage with or without DC prestressing could initiate an electrical tree. The tree initiation ratio increased due to higher impulse voltage, increased DC prestress level and shorter rest time between DC prestress and impulse voltage. The measured initial tree length showed a proportional relation with the impulse magnitude, whereas it was almost independent of DC prestress level and the rest time. The observations are explained by the injection, accumulation, dissipation, trapping and detrapping of space charges in the region around the needle tip.

Temperature Effect on Electrical Treeing and Partial Discharge Characteristics of Silicone Rubber‐Based Nanocomposites

“…Power cables are subjected to high and continuous voltage as well as mechanical and thermal stresses that induce and accelerate the cable ageing and insulation breakdown. Electrical treeing is one such breakdown phenomenon that occurs in insulation cables, and many researchers have presented studies done on electrical treeing phenomena in insulation cables [2][3][4][5][6][7]. Treeing occurs inside the dielectric when partial discharges are initiated and progresses under electrical stress through paths that are tree-like.…”

Electrical Treeing in Cable Insulation under Different HVDC Operational Conditions

“…In the scenarios of pure DC voltages, the phenomenon of treeing was investigated at continuous and non-continuous DC voltages as proposed in [19], where treeing phenomenon was investigated using needle-plane electrode arrangement. The first scenario can be considered as the long-time operation of an HVDC link in either polarity; DC voltages of linearly increasing function were applied to the test sample, in a way the voltage increased from zero level with the rising rate of 500 V/s to a predetermined value.…”

The coming of Age of HVDC extruded power cables

“…The partial discharges required would be unipolar and so charge would need to be conducted through the XLPE both as a source and a sink of charge for the discharge. DC trees have been observed, especially where there are significant voltage transients or impulses [26]. It seems likely that significant partial discharges under HVDC are only to be found during switching (i.e.…”