Impact of mechanical deformation on space charge in XLPE

Chen, G.; Kamaruzzaman, M. R.

doi:10.1109/icsd.2007.4290863

Cited by 8 publications

(7 citation statements)

References 4 publications

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“…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]. When XLPE is bore the tensile stress, the heterocharges dominate the space charge accumulation in the deformed XLPE, while homocharges govern the process in undeformed XLPE at low applied electric field [74]. Effects of mechanical stretching on electrical properties of LDPE/MgO nano‐composites are studied, it is found that the interface region increases after mechanical stretching, and the trap density and energy level become larger.…”

Section: Influencing Factors Of Electrical Treementioning

confidence: 99%

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%

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

Su¹,

2020

High Voltage

105

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“…In [21] tensile stress was applied to XLPE which increased the amount of heterocharge in the material. For other insulating materials tensile stress has enhanced space charge related breakdown whereas compressive stress suppressed them [22].…”

Section: B High Voltage DCmentioning

confidence: 99%

Material considerations for submarine high voltage XLPE cables for dynamic applications

Sonerud

Eggertsen

Nilsson

et al. 2012

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Special consideration is necessary choosing materials and selecting design for dynamic cables due to the mechanical stress, sometimes in combination with a wet design, experienced by the cable. For high voltage cables (>36 kV) this is mainly related to the required (IEC 60840) metallic water barrier and for wet solutions the influence of water treeing and the associated accelerated electrical aging is of concern. Lead is commonly used as a radial water barrier for high voltage cables but the fatigue resistance is inferior to steel and most other metallic materials due to its low melting temperature and poor mechanical properties. For these reasons it is generally not considered suitable as a radial water barrier for dynamic power cables. Alternatives such as longitudinally welded copper sheaths have proved to be viable alternatives to lead and studies on nonmetallic barriers have been performed which show promising results. For wet medium voltage designs or designs which allow some moisture ingress into the insulating material water treeing is often a concern. However, it has been shown that high relative humidity (>70%) is necessary for water tree inception. By delaying the water ingress with sheaths and swelling tapes the time to reach critical humidity levels in the material can be increased from 1 month to several decades. The influence of hydrostatic pressure and compressive stress has been found to diminish water tree growth whereas tensile stress enhances it. For dc voltages there are indications that both humidity and mechanical stress can increase accumulation of charge in the insulating material. It has also been shown that moisture ingress will increase the conductivity which could influence breakdown strength negatively.

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“…The PEA technique was chosen to detect space charge in samples due to its simplicity in structure, low cost and easy to implement [10]. The measuring device of PEA system used in this paper is shown in Fig.…”

Section: Space Charge Measurementmentioning

confidence: 99%

Effect of thermal ageing on space charge characteristics of cross-linked polyethylene

Xiang

Zhou

et al. 2014

2014 ICHVE International Conference on High Voltage Engineering and Application

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In order to understand the thermal ageing effect on space charge characteristics of XLPE in the strong DC field, accelerated thermal ageing tests were conducted on XLPE samples. In this study, dicumyl peroxide (DCP) and low density polyethylene (LDPE) was selected to prepare samples. The PEA method was utilized to measure the space charge distribution characteristics of aged samples under DC voltage (50kV/mm). The impact of ageing on the internal space charge evolution as well as the average space charge density was discussed. Experiments and analysis results show that thermal ageing induces negative charge traps to samples and increases both the deep and shallow charge traps. Furthermore, it indicates that space charges distribution and the average charge density reflect the insulation properties of samples. The internal structure of XLPE specimens is changed and the insulation properties of specimens degraded as the aging time prolonged. These results provide theoretical support for further research on the effect of the space charge characteristics on properties of the power cables.

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Impact of mechanical deformation on space charge in XLPE

Cited by 8 publications

References 4 publications

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

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

Material considerations for submarine high voltage XLPE cables for dynamic applications

Effect of thermal ageing on space charge characteristics of cross-linked polyethylene

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