Influence of mechanical pressure on space charge penetration behavior in low-density polyethylene (LDPE) sheet

Mohamed, Amir Izzani; Saari, Mohd Mawardi; Ozaki, Ryotaro; Kadowaki, Kazunori

doi:10.23919/iseim.2017.8088718

Cited by 10 publications

(4 citation statements)

References 6 publications

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“…The space charge penetration behaviours are investigated in LDPE sheet with different mechanical pressure, it is found the space charge penetration is gradually reduced and restricted with the increase of mechanical pressure as shown in Fig. 12 [72]. As the compression force increases, the mean current density becomes smaller and the space charge amount is also reduced inside the polymer matrix, which is related with the volume reduction in the vacant space [73].…”

Section: Influencing Factors Of Electrical Treementioning

confidence: 99%

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Electrical tree degradation in high‐voltage cable insulation: progress and challenges

Su¹,

2020

High Voltage

105

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High‐voltage direct current (HVDC) and high‐voltage alternating current (HVAC) cables are the most important equipment for high‐voltage, large‐capacity and long‐distance power transmission. Electrical tree is a pre‐breakdown phenomenon leading to failure of insulation materials, and it is the major issue that threatens the safe and stable operation of HVDC and HVAC cable systems. This study summarises and analyses the achievements in the research of electrical tree for HVDC and HVAC cables. The initiation mechanisms of the electrical tree, including Maxwell electro‐mechanical stress, charge injection–extraction, charge trapping and electroluminescence theories, are elaborated for fully understanding the electrical degradation process in insulation materials. Then, the influences of the high electric field, high temperature and mechanical stress on electrical tree behaviours are discussed, and the relationship between charge transport and the electrical tree is analysed and illustrated. The suppression methods of the electrical tree are put forward by introducing inorganic and organic additives into insulation materials, and the suppression mechanisms are presented from the viewpoints of the structure‐property and microscale–macroscale relationships. Recently, the electrical tree research studies are focused on the high‐precision of initiation models, high‐dependence of multi‐physical fields and high‐efficiency of suppression methods. The achievements provide theoretical support for improving the electrical performance of insulation materials, while it is a practical problem to explore their application feasibility in HVDC and HVAC cable.

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Section: Influencing Factors Of Electrical Treementioning

confidence: 99%

“…Space charge penetration behaviour with different pressures[72] and CED as a function of compressive ratios…”

mentioning

confidence: 99%

Electrical tree degradation in high‐voltage cable insulation: progress and challenges

Su¹,

2020

High Voltage

105

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“…The free radicals generated during the fracture of molecular chains act as chemical traps to bind the space charge. In the literature [17], the space charge of low‐density polyethylene sheets under mechanical forces was measured. It was found that the penetration of space charge within the sheet was limited when the sheet was subjected to compressive forces.…”

Section: Introductionmentioning

confidence: 99%

Study on the measurement method of polyimide electrical properties for flexible solar wing

Wang

Qin

et al. 2023

IET Nanodielectrics

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Flexible solar wings with high energy density, lightweight, small size and large deployment area are one of the first choices for next‐generation spacecraft. However, the flexible solar wings are subjected to irradiation in space and tensile mechanical stress, which produce the charge accumulation effect and result in electrostatic discharge. It is necessary to establish a test method for the conductivity and space charge behaviour of polyimide under tensile stress. The stress–strain characteristics of polyimide under different tensile stresses are studied by the authors. The longitudinal length‐strain characteristics and transverse thickness evolution characteristics under different stresses are also obtained. The results show that the variation of film thickness with tensile force is only about 1% before the yield point. The polyimide films from 50 to 200 μm thick have similar yield and tensile strengths. The ultimate stress of the specimen decreases from approximately 126 to 103 MPa with increasing thickness. The thickness model of polyimide under tensile stress were obtained, which could accurately calculate the voltage amplitude applied on the specimens for measuring the conductivity under different tensile stresses. A basis for investigating the stress–strain characteristics of polyimide films under different tensile stresses are provided, which will facilitate the formulation selection and performance improvement of polyimide for flexible solar wings of spacecraft.

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“…A. I. Mohamed et al investigated the effect of compressive stress on the space charge properties of low density polyethylene. The results of the study showed that the penetration of space charge within the sheet was limited when the material was subjected to compressive stress [ 9 ]. Du et al measured the trap distribution of PP/POE blends with different elongation ratios and found that the trap depth first became shallower and then increased as the elongation ratio increased, showing that the main reason why stretching affects the trap distribution characteristics is the change in specimen structure [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Mechanical Stress on Insulation Structure and Performance of HV Cable

Su¹,

Wei²,

Zheng

et al. 2022

Polymers

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Mechanical stresses generated during manufacturing and laying process of high voltage cables can result in degradation of insulation properties, affecting the stable operation of the transmission system. Traditional test methods for testing the effect of mechanical stress on the insulation properties of polyethylene still have some shortcomings to be explored and it is able to explain the changes of the insulation properties of polyethylene under mechanical stress from a microscopic perspective. In order to further study the effect of stress on the insulation properties of polyethylene, microstructural changes, the breakdown field strength, conductivity and charge distribution of polyethylene at different elongation rates are investigated by a combination of experimental and molecular dynamics simulations. The results show that the increase in stress leads to a decrease in crystallinity and microcrystalline size of the material decrease. The untwisting and orientation of the polyethylene molecular chains during the stretching process can create cavities, resulting in an uneven sample distribution and thickness reduction, leading to a reduction in the breakdown field strength. Meanwhile, some crystal regions are transformed into amorphous regions. The loose amorphous regions facilitate the directional migration of carriers, resulting in the increase of conductivity. When the elongation ratio is smaller, the distance between the molecular chains increases and the trap depth of the specimen becomes shallower. This facilitates the migration of ions and electrons and increases the rate of decay of the surface potential. When the stretch is further increased, the trap depth will become larger, decreasing the decay rate of the surface potential and reducing the insulation properties of the polyethylene. Meanwhile, the molecular dynamics model of semi-crystalline polyethylene was developed to observe the microstructure and energy changes during the stretching process. The conclusions in terms of tensile tests were verified from a microscopic perspective.

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Influence of mechanical pressure on space charge penetration behavior in low-density polyethylene (LDPE) sheet

Cited by 10 publications

References 6 publications

Electrical tree degradation in high‐voltage cable insulation: progress and challenges

Electrical tree degradation in high‐voltage cable insulation: progress and challenges

Study on the measurement method of polyimide electrical properties for flexible solar wing

Effects of Mechanical Stress on Insulation Structure and Performance of HV Cable

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