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We investigated how high permittivity materials affect the S-parameters and transmit efficiency of a head-sized birdcage coil. We also studied whether re-tuning and matching are necessary for improved performance. While adjusting the S-parameters is possible during coil development and for prototype coils, it is often unfeasible to re-tune and match commercially manufactured coils, and poses a challenge...
The use of polymer nanocomposites - a material system composed of nanometer-sized fillers (nanofillers) homogeneously dispersed in polymers - is predicted to be capable of enhancing the performance of electrical insulation systems without compromising the thermal, mechanical and economic requirements. This is believed to be related to the much smaller size of the fillers, which subsequently leads...
Measurement of partial discharge (PD) in high voltage equipment is widely used in condition assessment and performance maintenance of the insulation system. One of the methods to evaluate PD data from condition monitoring activities is by analysing PD signals captured from the PD detection equipment. In high voltage power cable, PD pulses originated from defect sites within cable insulation can propagate...
The potential of polymer nanocomposites as dielectric materials is an active area of research, due to the promising electrical properties that may result from nanostructuration. Recently, the effect of water absorption in nanocomposites has been considered and it is found that nanocomposites can absorb significantly more water than the equivalent unfilled polymer when exposed to humid environmental...
Defect in a cable joint is one of the main reasons of a power system being faulty. A defect can cause the electric field in the cable joint to become higher than the material surrounding the defect. This may result in partial discharge (PD) activity to occur within the defect site. When PD is repeating at the defect site, the material surrounding the defect will be affected, where PD may extend its...
Frequency domain spectroscopy (FDS) has been used to assess the ageing condition of oil-paper insulation used in transformers. To further understand the ageing process, the reduction in degree of polymerization (DP) of cellulosic paper in itself on the dielectric response was investigated first. It has been found that the reduction in DP itself can alter the dielectric characteristics. The oil-paper...
0.57(Bi0.8La0.2)FeO3-0.43PbTiO3 (BLF-PT) ceramics were successfully prepared by sol-gel technique combined with solid-state reaction method. X-ray diffraction (XRD) results revealed that single crystallites with rhombohedral phase could be obtained at 600 °C for 2 h, which is 150 °C lower than that required to prepare single phase material with the same composition from solid-state reactions. The...
Epoxy resin is widely used in high voltage apparatus as insulation. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. The addition of fillers can deteriorate electrical performance. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite...
To study the electromagnetic properties of nanowires composed of various materials at infrared and optical frequencies, the dispersive nature of the material must be incorporated into the modeling approach. In the paper, the use of the complex dielectric function and mathematical models for the dispersive properties of the material, specifically in this case for Gallium Phosphide (GaP) material is...
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