Abstract
This paper prepares polyethylene/silica nanocomposites with concentrations of 3 wt% and 5 wt% by using silicon dioxide (SiO2) nanopowder (nanosilica) with particle sizes of 15 and 50 nm. Samples whose elongations are 3%, 6%, and 10% are prepared. Pulsed electroacoustic technique is applied to evaluate the space charge distribution in samples. Test results show that homocharge near electrodes is generated in the polyethylene/silica nanocomposites. Nanocomposites with a nanoparticle concentration of 3 wt% and particle size of 15 nm suppress the accumulation of space charge effectively. The amount of space charge in the samples increases with the increase in elongation. At an elongation of 10%, packet-like space charge is generated in polyethylene/silica nanocomposites with the concentration of 5 wt% and particle sizes of 15 and 50 nm. The packet-like space charge in nanocomposites whose particle size is 50 nm is more obvious than that in nanocomposites whose particle size is 15 nm. The experiment results are explained by applying interface characteristics, dipole model, and induced dipole model.
Highlights
The accumulation of space charge in polymer insulation makes a change of electric field
This result proves that polyethylene/silica nanocomposites can suppress the accumulation of space charge
Compared with the polyethylene/silica nanocomposites whose particle size is 50 nm, homocharge accumulation occurred when the concentration was only 3 wt%, shown in According to Figure 2, there are more space charges near positive and negative electrodes for the nanocomposites whose elongation is 3% and 6% compared with the nanocomposites without elongation
Summary
The accumulation of space charge in polymer insulation makes a change of electric field. Mechanical and electrical properties can be effectively improved through the use of nanomodified materials. Cables are inevitably affected by mechanical stress during manufacturing, transportation, installation, and operation Such stress may cause the insulation materials of cables having elongation [7, 8]. Additional research on the electrical properties of polymer insulation during elongation should be conducted. With regard to insulation materials with an accumulation of space charge, there will be electrical trees by applying mechanical stress without electrical stress [9]. The mechanical stress caused by the electric field is considered the reason for breakdown in polymer insulation [11]. The conclusion that the electrical properties of insulation may be affected by mechanical stress has been confirmed. More research on this area should be conducted
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