Key Technical Analysis of Power Cable Structure Recovery Based on Mould Melt Joint

As the expansion of power industry, the increasing diversity of power transmission, and the needs in urban power consumption, hydropower transmission and undersea transmission, and environmental protection, lead to the increasing application of power cables in both amount and types. We summarized the characteristics, development and present practical application of power cables worldwide, and made prospects about the main trends of power cable structure recovery development in the future. Moreover, we discussed the main topics about power cable structure recovery such as high performance dielectric material, aging of electrical tree, space charge accumulation, design of insulation structure, and operation detection. It is concluded that the application of power cable structure recovery will be an important part in power transmission, but it has to overcome some key problems such as space charge accumulation. The needs for power cable structure recovery are closely related to the requirements in aspects of society, economy, and environment. Power cable system reliability mainly depends on power cable accessories that form the main weak point of the whole power cable system. That results in many failures such as HV and EHV power cable accessories. The cause consists in the fact that the accessories workmanship and quality. Mould melt joint is the new method to fully restore original cable body structure on the cable joints in the field, so that the electrical properties of the connection of power cable body equalization reach a high-security state. Mould Melt Joint can fully restore original cable body structure on the cable joints in the field, so that the electrical properties of the connection of cable body equalization reach a high-security state. The cable conductor, inner semi-conductive layer, the primary insulation and outer semi-conductive layer on the mould melt joint joints will fully recover the cable body in accordance with the original structure of the cable. There is no stress cone assembly structure. So the cable connections become complete cable without cable joins. The technique has obvious technical advantages compared with traditional power cable joint. Mould Melt Joint specification is almost equal to power cable outer diameter, which will occupy less space than traditional power cable accessories and could be applied in occasion such as sinuosity and high-altitude. Mould melt joint has been applied in many occasions with good effect, indicating a good application prospect. At present, some of the power cable line are operating with defect because of poor workmanship, especially in power cable accessories. Mould melt joint technology meets the demand to quickly recovering the failure power cable using a new method. Mould melt joint mainly used in the middle connection of MV, HV and EHV XLPE insulated power cable, such as 10 kV, 20 kV, 35 kV, 66 kV, 110 kV, 132 kV, 220 kV, 500 kV, and also DC submarine cables, the voltages is 160 kV, 200 kV, 320 kV and 400 kV. For the accidentally destroyed cable in the running or lying, Mould melt joint techniques can also repair the cable. This technology will provide strong support for realizing safe, reliable and efficient operation of the power cable system, cutting down failures rate and AC and DC flexible joint for marine cable. It is concluded that, power cable structure recovery based on Mould Melt Joint will become more and more important in the power industry.