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To understand the space charge formation of nano-sized magnesium oxide (MgO)/low-density polyethylene (LDPE) nanocomposite materials, the space charge and the conduction current up to the breakdown has been investigated under increasing DC ramp field. A negative charge was dominated in the 0 phr sample. A positive charge was dominated in nanocomoposite sample. The field increment (= the maximum field...
To understand DC breakdown phenomena of low density polyethylene (LDPE) mixed with nano-sized magnesium oxide (MgO), the electric properties, namely, DC breakdown strength, conduction current, space charge formation and local heat generation up to the breakdown under increasing field with a particular rate of increase was investigated. DC breakdown strength of nanocomposite was found to be high compared...
To understand the space charge formation of nano-sized magnesium oxide (MgO)/low-density polyethylene (LDPE) nanocomposite materials, the space charge up to the breakdown has been investigated under DC increasing ramp field. A negative charge was dominated in 0 phr sample. A positive charge was dominated in nano-composite sample. The field increment (= the maximum field - the average field) of 0 phr...
Processes of tree initiation and growth in LDPE/MgO nanocomposites were investigated by using optical and partial discharge (PD) detection methods. They can be divided into three stages depending on tree length. The first stage corresponds to the initial growth of about 10 ??m and might be subtly affected by the filler content up to 1 phr. This might be influenced by Coulombic field formed around...
The relationship between space charge accumulation and breakdown at various temperatures is investigated by observing the space charge formation in low density polyethylene (LDPE) and LDPE/MgO nanocomposite material under dc high stress. We have reported, earlier, that, enhancement of electric field in LDPE by packet-like charge under dc stress might be a cause of its electrical breakdown. Furthermore,...
To understand treeing phenomena in MgO/LDPE nanocomposite under ac voltage application, treeing breakdown properties and partial discharge inception voltage were investigated. Tree inception voltage increased with increasing filler content. Time to bridge counter electrode, time to breakdown and time-lag to breakdown also increased with addition of MgO nano-filler to LDPE. From these results, it becomes...
To understand basic electric properties of nano-sized magnesium oxide (MgO) / low-density polyethylene (LDPE) nanocomposite materials, the temperature dependence of breakdown strength and the space charge up to the breakdown has been investigated under DC ramp field. At temperatures at which these investigations were carried out, DC breakdown strength of the sample with the MgO nano-filler (hereafter,...
A nano-composite material is attracting many researchers' attention in the field of dielectric and electrical insulation. The purpose of this study is to investigate the influence of MgO filler size on electrical properties of MgO/LDPE nanocomposite. The volume resistivity, DC breakdown strength and the impulse breakdown strength of low-density polyethylene (LDPE) containing nano-filler or micro-filler...
This paper deals with initiation of light emission and electrical trees in LDPE/MgO nanocomposite. Specimens were prepared in such a way that a tungsten needle of 50 mum phi and 1mumR was inserted into dielectrics with a spacing of 0.4 mm between high voltage and ground. Light emission was observed by an ICCD camera, and tree shapes were examined by an optical microscope. As a result, it was found...
To understand basic electric properties of nano-sized magnesium oxide (MgO) / low-density polyethylene (LDPE) nanocomposite under DC voltage application, DC breakdown strength and the space charge up to the breakdown under DC ramp voltage were investigated. DC breakdown strength of 1 phr sample contained 1 phr MgO nanofiller (hereafter, called 1phr sample) increased compared with that of 0 phr sample...
In spite of the bourgeoning evidence of improvements in material properties, the mechanism of conduction and breakdown in nanocomposite dielectrics is not yet clear. Understanding the macroscopic properties of nanocomposites is essential for the use and application of the nanodielectrics as also to pave the way for providing an understanding at nano-scale. Any hypothesis explaining the nano-scale...
To understand basic electric properties of nano-sized magnesium oxide (MgO) / low-density polyethylene (LDPE) nanocomposite under DC voltage application, the volume resistivity, the space charge distribution and the breakdown strength were investigated. By the addition of nano-sized MgO filler, both the DC breakdown strength and the volume resistivity of LDPE increased. At the average DC electric...
To understand basic electric properties of nano-sized magnesium oxide (MgO)/low-density polyethylene (LDPE) nanocomposite under DC voltage application, the volume resistivity, the space charge distribution, the breakdown strength and the short circuit tree were investigated. By the addition of nano-sized MgO filler, both the DC breakdown strength and the volume resistivity of LDPE increased. At the...
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