Space charge in dielectrics. Energy storage and transfer dynamics from atomistic to macroscopic scale

Journal of Applied Physics

Alghamdi

et al. 2015

Trapping parameters can be considered as one of the important attributes to describe polymeric materials. In the present paper, a more accurate charge dynamics model has been developed, which takes account of charge dynamics in both volts-on and off stage into simulation. By fitting with measured charge data with the highest R-square value, trapping parameters together with injection barrier of both normal and aged low-density polyethylene (LDPE) samples were estimated using the improved model. The results show that, after long-term ageing process, the injection barriers of both electrons and holes is lowered, overall trap depth is shallower and trap density becomes much greater. Additionally, the changes in parameters for electrons are more sensitive than those of holes after ageing.

Section: Trapping Cross-sectional Areamentioning

confidence: 99%

Section: Trapping Cross-sectional Areamentioning

confidence: 99%

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An improved model to estimate trapping parameters in polymeric materials and its application on normal and aged low-density polyethylenes

Journal of Applied Physics

Alghamdi

et al. 2015

“…(7), the rate of charge capture by traps will be proportional to the density of mobile holes , unoccupied trap sites' density − ,where represents the a total traps density for holes, and is the drift velocity of charge carriers. Moreover, we correlate trapping cross section area with trap depth and local electric field [8,9].…”

Section: ) Volts-on Conditionmentioning

confidence: 99%

Trapping parameters estimation of fresh and thermally-aged low-density polyethylene by using an improved trapping/detrapping model

2015 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

et al. 2015

Abstract-In the present paper, trapping parameters of normal and thermally aged low-density polyethylene (LDPE) samples were estimated using the improved charge dynamic model. The results show that, after long-term thermal ageing process, the injection barrier of both electrons and holes is lowered, the overall trap depth is shallower and electron trap density becomes much greater. The latter may indicate that electrons are more sensitive to ageing than those of holes.

“…Physically, it can be explained that smaller capture radius will give rise to a greater coulombic attractive force upon on charge carrier, hence forming a deeper trap, which is harder for charge carrier to escape. Especially in [9], it was proposed that he binding energy of a coulombic trap to charge carrier is inversely proportional to radius of the trap . The binding energy directly determines the trap depth .…”

Section: Model Of Charge Dynamicsmentioning

confidence: 99%

Trapping parameters comparison between cable sections from different service conditions by a new trapping-detrapping model

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

Yang

2014

Abstract-Space charge formation will cause electric field enhancement at certain location in the polymeric materials, especially under HVDC insulation condition. In our previous works, a model has been developed which is suitable for analysing the space charge data from depolarization test to calculate the material trapping parameters. In the present paper, two cross-linked polyethylene (XLPE) cables, taken from HVAC service condition of 220kV for 12 years and for 8 years, were peeled as 100-200μm films from the outer to inner layer of insulation. Through the comparison between trapping parameters estimated from our model, it has been found that samples from inner insulation layers for both cables have the deepest trap depth and the greatest deep trap density, indicating samples from inner layers have the severest ageing.