Interface Damages of Electrical Insulation in Factory Joints of High Voltage Submarine Cables

Zhen-Peng Zhang, Chang-Ji Zheng, Mei Zheng, Hong Zhao, Jian-Kang Zhao, Wei-Feng Sun and Jun-Qi Chen
Additional contact information
Zhen-Peng Zhang: China Electric Power Research Institute, No.143 Luoyu Road, Hongshan District, Wuhan 430074, China
Chang-Ji Zheng: Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China
Mei Zheng: State Grid Zhejiang Electric Power Co. Ltd, Hangzhou 310000, China
Hong Zhao: Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China
Jian-Kang Zhao: China Electric Power Research Institute, No.143 Luoyu Road, Hongshan District, Wuhan 430074, China
Wei-Feng Sun: Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China
Jun-Qi Chen: Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China

Energies, 2020, vol. 13, issue 15, 1-14

Abstract: As a key accessory of high-voltage (HV) insulated submarine cable, the factory joints of the cross-linked polyethylene (XLPE) represent an unpredictable uncertainty in cable-connecting fabrications by means of the extruded molding joint (EMJ) technique. The electrical breakdown pathways formed at the interfaces between recovery insulation and cable body under alternative current 500 kV voltages are specifically investigated by microstructure characterizations in combination with the electric field and fractal simulations. Dielectric-defected cracks in tens of micrometers in insulation interfaces are identified as the strings of voids, which dominate insulation damages. The abnormal arrangements of XLPE lamellae from scanning electron microscopy (SEM) imply that the structural micro-cracks will be formed under interface stresses. Electrical-tree inception is expedited to a faster propagation due to the poor dielectric property of interface region, manifesting as 30% lower of tree inception voltage. The longer free-paths for accelerating charge carriers in the cracks of interface region will stimulate partial discharging from needle electrodes. The carbonized discharging micro-channels arising in interface region illustrate that the partial discharging will be triggered by the electrical-trees growing preferentially along the defect cracks and could finally develop into insulation damages. The mechanism of forming cracks in the fusion processes between the molten XLPE of cable body and the molten cross-linkable PE of recovery insulation is elucidated, according to which the crack-caused degradation of insulation performance is expected to be alleviated.

Keywords: cross-linked polyethylene; dielectric breakdown; electrical tree; factory joint; high voltage cable (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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