Temperature dependent trap level characteristics of graphene/LDPE nanocomposites

Li, Zhonglei; Yang, Zhiduan; Han, Chong

doi:10.1109/tdei.2017.006850

Cited by 23 publications

(17 citation statements)

References 29 publications

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“…The double exponential function can be used to simulate the surface potential decay curve with time [20], which can be expressed as following:…”

Section: Mathmentioning

confidence: 99%

“…According to the theory proposed by Simmons and Tam, it is assumed that the detrapping charges will not be captured by traps again during the surface potential decay process with the electron-hole recombination being ignored [21,22]. The trap distribution in sample can be calculated from the surface potential decaying curves [20], as the trap level density be presented by:…”

Section: Mathmentioning

confidence: 99%

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Effect of Moistures on Space Charge and Trap Level Characteristics of Oil-Impregnated Pressboards

et al. 2020

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Oil-paper insulation as an irreplaceable insulation system in the electrical power transformer is inevitably suffering the water intrusion on working condition, which will make dielectric performance degraded and insulation aging accelerated. In high interest of explaining the deterioration effect of absorbing moisture on the dielectric properties of oil-paper insulation system and corresponding mechanism, the space charge and trap level characteristics are investigated for the specially prepared oil-impregnated pressboards with different moisture contents. The Pulsed Electro Acoustic and Isothermal Surface Potential Decay experiments are performed to test the space charge distributions and evaluate the trap level depths, respectively. It is indicated that the polarity of injected space charges is alternated with the decaying rate being raised when the absorbing moisture is aggravated in oil-impregnated pressboards. The charge carriers are more prone to be captured by the shallow-level traps that have been introduced by water permeation near pressboard surface than the intrinsic deep-level traps inside pressboard. The captured charge carries accounts for the significantly exacerbated space charge accumulation as manifested by the surface charges of oil-impregnated pressboards.

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“…The double exponential function can be used to simulate the surface potential decay curve with time [20], which can be expressed as following:…”

Section: Mathmentioning

confidence: 99%

Section: Mathmentioning

confidence: 99%

Effect of Moistures on Space Charge and Trap Level Characteristics of Oil-Impregnated Pressboards

et al. 2020

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“…It is known that the temperature will affect both the electrical tree inception and growth processes [16]- [20]. The electrical tree inception is related to the electron injection-extraction process and charge transport [21], [22], and the growth characteristics are determined by partial discharge (PD) and space charge accumulation [23], [24]. The charge behavior of insulation makes the distortion of the electric field inside cable accessories more severe, readily leading to insulation degradation [17], [23], [25].…”

Section: Introductionmentioning

confidence: 99%

Effects of Temperature Gradient on Electrical Tree Growth and Partial Discharge in Silicone Rubber Under AC Voltage

et al. 2020

IEEE Access

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The Joule heat produced by the current in conductor decreases in the radial direction, producing a temperature gradient in the insulation. This existing temperature gradient can affect the electrical tree phenomenon in insulation materials because of the temperature dependence of insulation material, charge migration and tree growth. Different temperature gradients were obtained by controlling the temperature of high voltage (HV) and ground electrode (GD) sides. The electrical tree was recorded by a microscope, while the partial discharge (PD) was observed simultaneously. For better understanding the effects of the temperature gradient on electrical tree inception, the trap distribution in silicone rubber (SIR) with different temperature was analyzed by isothermal discharge current (IDC) method. With the fixed temperature in HV or GD side, it was found that the electrical tree inception voltage decreased linearly with increasing temperature in either side. The IDC results indicate that the increasing temperature contributes to the de-trapping of charges and lowers the inception voltage. Besides, the electrical tree length and accumulated damage gradually increase with the temperature gradient. The observed PD amplitude and quantity also increase with the temperature gradient, which facilitates the growth of electrical trees. These results indicate that the tree growth is promoted with an increase in the temperature gradient of the cable insulation, posing a threat to the safety of the cable system. INDEX TERMS AC plastic cable, cable accessories, silicone rubber, electrical tree, temperature gradient, tree inception, growth characteristics, partial discharge.

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“…It is therefore speculated that a the addition of a tiny amount of graphene (much lower than the amount of traditional nanoparticles) could bring a large quantity of nanofiller-polymer interface regions, but also avoid the agglomeration of nanofillers, thus exploiting further potentials of nanodielectrics. Recent investigations have proved that graphene with a content of 0.005 wt % could increase the deep trap level and reduce the carrier mobility of LDPE nanocomposites [ 21 , 22 ]. However, local agglomeration occurs in 0.01 wt % graphene/LDPE nanocomposites, resulting in a decrease of the deep trap level [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

“…Recent investigations have proved that graphene with a content of 0.005 wt % could increase the deep trap level and reduce the carrier mobility of LDPE nanocomposites [ 21 , 22 ]. However, local agglomeration occurs in 0.01 wt % graphene/LDPE nanocomposites, resulting in a decrease of the deep trap level [ 21 ]. There is still a limit to the understanding of correlation between the space charge characteristics and its trap level distribution in graphene/LDPE nanocomposites, which is important for the extruded insulation, especially at the operating temperature.…”

Section: Introductionmentioning

confidence: 99%

Inhibition Effect of Graphene on Space Charge Injection and Accumulation in Low-Density Polyethylene

Hou

et al. 2018

Nanomaterials

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Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density polyethylene (LDPE). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images were employed to observe the dispersion of graphene with a two-dimensional structure in LDPE. The time-dependent space charge dynamic behaviors of graphene/LDPE nanocomposites with the filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were characterized by the pulsed electro-acoustic (PEA) test at 40, 60 and 80 °C, and the charge mobility was evaluated by its depolarization processes. The experimental results show that for the undoped LDPE film, large amounts of space charges were injected from the electrodes into samples, especially at 60 and 80 °C. The graphene/LDPE nanocomposites with a filler content of 0.005 wt % could markedly suppress the space charge injection and accumulation even at 80 °C, which is attributed to the large quantities of graphene-polymer in interface regions. These interface regions introduced numbers of deep trap sites within the forbidden band of nanocomposites, which can reduce the de-trapping rate of charges and suppress the space charge accumulation in the polymer bulks. The graphene/LDPE nanocomposites are suggested for dielectric applications, intending the inhibition of space charge injection and accumulation.

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Temperature dependent trap level characteristics of graphene/LDPE nanocomposites

Cited by 23 publications

References 29 publications

Effect of Moistures on Space Charge and Trap Level Characteristics of Oil-Impregnated Pressboards

Effect of Moistures on Space Charge and Trap Level Characteristics of Oil-Impregnated Pressboards

Effects of Temperature Gradient on Electrical Tree Growth and Partial Discharge in Silicone Rubber Under AC Voltage

Inhibition Effect of Graphene on Space Charge Injection and Accumulation in Low-Density Polyethylene

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