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When power cables are loaded under high voltage direct current (HVDC), an accumulation of space charge and a radial distribution of temperature gradient are developed across the insulation material. Such existence and accumulation of space charge within the insulating material poses a threat to the reliability of the operation of dc power cables. The electric field of a practical dc power cable is...
Partial discharge (PD) activity is always linked to insulation degradation, which can affect the performance of the insulation. Therefore, measurement of PD events can be used to assess the condition of the insulation. To assist the assessment of the performance of insulation materials, modelling of PD events can be used to attain a better understanding of this phenomenon. In this paper, a Finite...
Partial discharge (PD) events within a closed-volume cavity in a dielectric material can cause a temperature change in the cavity. This may influence the occurrence of following PDs because the pressure in the cavity is affected, which changes the inception voltage level for the next PD. In this paper, a two-dimensional axial symmetric model geometry consisting of a spherical cavity within a homogeneous...
Monitoring surface potential decay of a corona charged polymeric material is a powerful tool to characterize electrical properties such as charge transport, trapping/detrapping and recombination. Over the years, various models have been proposed to describe charge transport within the material and one common feature in these models is that they were all based on single charge injection from the charged...
Distribution of electric field across the insulation of high voltage direct current (HVDC) is affected by the conductivity of the material, which is a function of both temperature and electric field. To understand the effect of temperature on the conductivity of the insulation across a dc power cable under load condition, an investigation is conducted on the electrical conductivity of the cross-linked...
Solid dielectrics have been used extensively in electrical and electronic industries. In the power industry, ultra high voltage transmission and cost saving of power equipment often result in that the dielectrics are operating under high electric fields. On the other hand, reduction in size for modern electronic systems also requires that the dielectrics operate reliably under high electric fields...
The pattern of partial discharge (PD) occurrence at a defect site within a solid dielectric material is influenced by the conditions of the defect site. This is because the defect conditions, mainly its size and location determine the electric field distributions at the defect site which influence the patterns of PD occurrence. A model for a spherical cavity within a homogeneous dielectric material...
A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of DC power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial AC XLPE power cables under an application of 80 kV DC supply...
Nanodielectrics have been extensively researched in recent years with the expectation that they may enhance electrical performance. In this paper we have studied the electrical conduction processes in linear low density polyethylene (LLDPE) filled with nano alumina particles. The electrical conduction was measured at various applied electric fields. It has been found that the conduction current shows...
It has been widely anticipated that the combination of recent advances in nanocomposites technology with traditional and novel resin systems may create materials with enhanced electrical, thermal and mechanical properties. It has been recognised that charge dynamics under an electric field play an important role in determining the electrical performance of a material. In this research, the pulsed...
Partial discharge (PD) is a discharge event that does not bridge the electrodes within an electrical insulation system under high voltage stress. In high voltage components, the measurement of partial discharge is used in the performance assessment of an insulation system. Through modeling the discharge process a better understanding of the phenomena may be attained. Previous studies have considered...
In direct current (DC) power cable the electric field is affected by conductivity of the material, which is a function of both temperature and electric field. Loading in high voltage direct current (HVDC) cable results in a temperature gradient across the insulation and hence a radial distribution of the insulation conductivity. A direct consequence is the accumulation of space charge within the insulation...
Apparent mobility obtained from space charge decay measurement has been recently used as an ageing marker to assess degradation of the insulation materials. The apparent mobility of charge carriers becomes slower after experiencing electrical ageing. In this paper, we have measured space charge decay in polymeric insulation material using the pulsed electroacoustic technique and studied apparent mobility...
This paper reports on the investigation into space charge characteristics at interfaces of multi-layer polymeric materials. Planar low density polyethylene (LDPE) samples were used in this study. DC voltage up-to 10 kV was applied to the sample and space charge measurements were taken using the pulsed electro-acoustic (PEA) technique. Experimental results indicated that the electrode interface plays...
Partial discharges (PDs) are harmful to electrical insulation as they may degrade the material. Consequently, a lot of efforts have been made to develop suitable systems for PD measurements and monitoring. Due to the complexity of PDs and many factors that can influence PD characteristics, the research on PDs is still very active and several models have been proposed over the years to understand the...
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