access icon openaccess Simulation of electrical trees in XLPE cable insulation and electric field analysis

This is an open access article published by the IET under the Creative Commons Attribution-NonCommercial-NoDerivs License (http://creativecommons.org/licenses/by-nc-nd/3.0/)
Received 28/08/2018, Accepted 19/09/2018, Published 24/10/2018

To understand the non-breakdown phenomenon during the accelerating electrical tree ageing in cross-linked polyethylene (XLPE) cable insulation, the non-breakdown mechanism of electrical tree is investigated in this study. The needle electrodes were inserted into the cable insulation samples to accelerate electrical tree ageing. The electrical trees which were not broken down had a larger expansion range and branch density. Referring to the actual cable slice for the internal structure of the sample, the electrical tree model with different number of tree channels was built. The correspondence between electric distortion and the number of tree channels was discussed. According to the calculation of the electric field distribution by the finite element method, the results showed that the electric field strength at the tip of electrical tree was reduced when the number of channels was increased. Compared with the single electrical tree channel, when the insulation was completely carbonised in the electrical tree region the electric field strength at the tip of electrical tree was reduced by 20.8%. The electric field shielding which was formed by the tips of electric trees could reduce the electric field strength at the tip of the tree and it could result in the formation of the non-breakdown electric tree.

Inspec keywords: finite element analysis; electric breakdown; XLPE insulation; ageing; trees (electrical); electric fields; power cable insulation

Other keywords: electric field distribution; tree channels; electrical tree model; finite element method; ekectric field shielding; cross-linked polyethylene cable insulation; electrical distortion; nonbreakdown electric tree; single electrical tree channel; needle electrodes; electric field strength; accelerating electrical tree ageing; electrical tree region

Subjects: Other heat and thermomechanical treatments; Dielectric breakdown and space-charge effects; Dielectric breakdown and discharges; Organic insulation; Power cables

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