Molecule diffusion behaviours of waterproof sealants into silicone rubber insulation for submarine cable joint based on molecular dynamics simulations

Abstract

The repair joints of high‐voltage cables play a significant role in the urgent cable maintenance, by recovering cable conductor, insulation, shielding layer and waterproof layer especially for submarine cables. However, the molecule diffusion and permeation processes from waterproof sealant into the cable joint insulation occur, leading to the insulation ageing and deterioration. In this article, the molecule diffusion behaviours of six typical molecules from the asphalt‐based and polyurethane‐based waterproof sealants into silicone rubber insulation are investigated. The results show that the order of diffusion coefficients is as follows, phenanthrene > fluoranthene > pyrene > benzo [k] fluoranthene > indeno [1,2,3‐cd] pyrene > polyurethane (PU). The relative molecular mass and binding energy are pivotal factors affecting the diffusion behaviour, while there is a linear relationship between the logarithm of the diffusion coefficient and the ratio of binding energy to relative molecular mass. Besides, the rising ambient temperature increases the fraction of free volume of silicone rubber and decreases the binding energy, thus resulting in a higher diffusion coefficient and an enhanced permeation process of the asphalt‐based sealant. In summary, the PU‐based waterproof sealant, with a much lower permeability than the asphalt‐based material, has a potential application in the waterproof layer for high‐voltage submarine cable repair joints.

Hydrogen evolution and electromigration in the corrosion of aluminium metal sheath inside high‐voltage cables

“…A carbon emission-free living environment is only possible if we utilise renewable energy resources such as solar, wind and hydro energy. But such power resources involved long-distance power transmission cables [1][2][3]. These transmissions involve high voltages and can only be achieved through a reliable moisture-proof and anti-corrosion insulation system [4][5][6].…”

High‐voltage frequency domain spectroscopy analysis of a thermally aged XLPE submarine cable under continuous and cyclic voltage based on carrier transport and polarisation characteristics

“…low-frequency dielectric loss curve is. The bending of the low-frequency dielectric loss (tanδ) is determined by the complex capacitance of the submarine cable as shown in Equation (3). It can be seen from Figure 12 that the lowfrequency (10 −3 -10 −1 Hz) curve of the ε' of the thermally aged submarine cable increases gradually under 10 kV voltage, compared with the ideal capacitance curve.…”

“…In recent years, the rapid development of offshore power transmission projects and renewable energy such as solar energy, wind energy and tidal energy has provided new historical opportunities for the development of extra high voltage (EHV) 500 kV submarine cables [1][2][3][4]. In 2019, the world's first AC 500 kV cross-linked polyethylene (XLPE) submarine cable was put into operation in Zhoushan, China.…”

Inhibiting liquid permeation into silicone rubber by superhydrophobic coating for prolonged service life

“…There are some studies on the permeation properties of liquid and molecule into SR [18][19][20][21], but no solution has been proposed to inhibit the liquid permeation process. Considering the importance of composite insulators for power transmission lines and the serious hazard of liquid permeation into composite insulators, it is of great significance to develop a simple approach to inhibit liquid permeation into SR.…”