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With the growing interest in HVDC transmission systems, the impact of space charge on insulation has attracted more attention recently and the traps in the materials are considered as one of the dominated factors that affect the electrical performance of the insulation. It has been found that a small amount of deep traps, introduced by slightly thermal ageing, suppress the space charge injection and...
Polyethylene is one of the widely studied polymeric insulation materials due to its application for cable insulation. One of the major issues related to polymeric materials is the easy accumulation of space charge which can cause local electric field distortion. This phenomenon is comprehensively studied under high voltage direct current (HVDC) stresses, but very rare under high voltage alternative...
Under the HVDC condition, the formation of the space charge in the oil paper system could affect the electric field distribution for converter transformers. Therefore, it is important to analyze the factors that determine the space charge behavior such as the temperature, moisture, electric field, oil paper thickness ratio and multilayers such as (Oil+Paper+Oil+Paper) structure. This paper focuses...
Space charge has been a general concern related with the reliability and the life-time of HVDC components. In this present work, the space charge profiles in oil-impregnated pressboards are investigated by the means of the pulsed electroacoustic (PEA) technique under AC voltage with 50 Hz at the room temperature. It has been observed that the ageing status of the mineral oil and the presence of the...
In the present paper, trapping parameters of normal and thermally aged low-density polyethylene (LDPE) samples were estimated using the improved charge dynamic model. The results show that, after long-term thermal ageing process, the injection barrier of both electrons and holes is lowered, the overall trap depth is shallower and electron trap density becomes much greater. The latter may indicate...
Space charge is an important factor that affects electrical properties of dielectrics such as the breakdown strength, especially under a dc field. Because the breakdown strength decreases as the film thickness increases, herein the space charge distribution was measured under a dc ramp voltage to understand space charge formation in low-density polyethylene (LDPE) with various thicknesses. The 0.10...
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