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Polymer nanocomposites have been attracting attention among researchers as electrical insulating application from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there are a lot more to explore as the characteristic of partial discharge in nanocomposites is not clearly understood as well as the electrical properties of the nanocomposites. By adding a few amount of weight percentage (wt%) of the nano fillers, the physical, mechanical and electrical properties of polymers can be greatly enhanced. This is due to its amazing characteristic of having large specific area as a consequential from its nano sized particle that could enhance the electrical properties of the insulator. For instance, nano fillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2), play big role in providing good approach to increase dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper based on previous experimental works and studies. This paper provides reviews from related publications from year 1997 to 2011 including the results of experimental works which have been conducted by the authors with main focus on partial discharge characteristics in polymer nanocomposites, which demonstrates that research and utilization of polymer nanocomposites has well developed from past decades and will possess a high demand in future as electrical insulating material.

Polymeric materials are widely used in power apparatus as electrical insulation especially as high voltage cable insulation. Meanwhile, partial discharge (PD) has always been a predecessor to major faults and problem in this field. Recent works showed that combination of natural rubber and polyethylene produces a good match of composite for electrical insulation. In this paper, blends of natural rubber, polymeric-based material of linear-low density polyethylene (LLDPE), nano-sized fillers of silica (SiO2) and titania (TiO2) were prepared by extrusion machine and moulding process. PD tests were carried out on each sample based on CIGRE Method II technique for 3 hours of ageing time. DAQ software was used as a tool to analyse the PD data, which measures PD pulse magnitude and number of PD occurrence. In addition, SEM images and percentage of element from EDX of the samples were taken before and after experiencing high voltage stress. The results revealed that there is a correlation between amount of filler and discharge activities.

Polymer nanocomposites have recently been attracting attention among researchers in electrical insulating applications from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there is a lot more to explore, as neither the partial discharge characteristic in nanocomposites nor their electrical properties are clearly understood. By adding a small amount of weight percentage (wt%) of nanofillers, the physical, mechanical, and electrical properties of polymers can be greatly enhanced. For instance, nanofillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2) play a big role in providing a good approach to increasing the dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper, with the different experimental and analytical techniques used in previous studies. This paper also provides an academic review about partial discharge in polymer nanocomposites used as electrical insulating material from previous research, covering aspects of preparation, characteristics of the nanocomposite based on experimental works, application in power systems, methods and techniques of experiment and analysis, and future trends.

Surface discharge is a common electrical discharge that normally occurs on the surface of outdoor insulators and also causes the failure in the electrical insulation system. One of the causes of surface discharge is the presence of high voltage stress. Experimental works had been carried out to examine the surface discharge characteristics on polymeric samples as insulation material. The IEC (b) electrode configuration had been used to investigate the surface discharges phenomena of different types of polymeric materials with controlled of air relative humidity (RH). In these experimental works, three types of polymeric sample were selected, namely high-density polyethylene (HDPE), ethylene-vinyl acetate (EVA), and polystyrene (PS), respectively. The characteristics of the discharge are critically depending on the types of polymer. Surface discharges intensity, number of discharge occurrence, and surface morphology of each polymeric material were also investigated. Comparisons of these electrical characteristics were conducted among the samples. Results from the experiment showed that the EVA samples experienced severe degradation as compared to HDPE and PS samples.

Electrical equipments mainly use polymeric material as insulation due to its characteristic of having high resistance to repel/retard electrical discharge attack, thermal conductivity, tree growth, and chemical cavities. Recently, polymer composite has been modified with addition of nano-sized filler instead of the conventional micro-sized filler. It was found that addition of nano-sized filler in polymer composite provides better characteristic if they are prepared and fabricated properly. The interfaces of the filler plays role in determining the behaviour of the polymeric insulation. Addition of different types of filler i.e. silica (SiO 2 ), titania (TiO 2 ), alumina (Al 2 O 3 ), zinc oxide (ZnO), magnesium oxide (MgO), clay, etc. also gives different dielectric behaviour to polymeric insulation. This paper provides a review on the effect of particle size and types of filler on polymeric material insulation. In attempt to identify the characteristic of these fillers on polymeric insulation, partial discharge (PD) amplitude, erosion depth, breakdown strength, glass transition temperature, and scanning electron microscopy (SEM) images of polymer composite samples are studied. The role of interfaces is also explained.

Polymers are widely used as insulation material because of their good insulation, physical and chemical properties. Nevertheless, electrification and degradation process due to partial discharge such as surface discharge usually occur and affects the life time of the insulation. The surface discharge can occur due to presence of high voltage stress which can lead to permanent insulation failure after many years if appropriate actions are not taken. One of the factors which cause this phenomenon is humidity. This paper investigates the effect of air relative humidity (RH) on surface discharge characteristics of polymeric material using IEC (b) electrode configuration. Result shows that the sample with higher RH revealed less surface discharge compared to other samples with lower RH. However, the sample with higher RH experiences more surface degradation compared to other samples with lower RH.