Contribution of surface conductivity to the current forms of partial discharges in voids

Wu, Kai; Ijichi, T.; Kato, Tatsuya; Suzuoki, Yasuo; Komori, F.; Okamoto, Tatsuki

doi:10.1109/tdei.2005.1561791

Cited by 24 publications

(5 citation statements)

References 13 publications

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“…Much research has been carried out to recognize the degradation of insulating materials by PD measurements, but most of the studies have been concerned with solid insulating materials, such as epoxy resins and polymer insulation [5,6]. Only a few investigations were focused on oilpressboard insulation.…”

Section: Introductionmentioning

confidence: 99%

Measurement and simulation of partial discharge in oil impregnated pressboard with an electrical aging process

Yao

et al. 2009

Meas. Sci. Technol.

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The continuous test on oil impregnated pressboard insulation with internal void defect was developed and the phase resolved partial discharge (PRPD) pattern of partial discharge (PD) signals during the electrical aging process was measured. Two different void structures which have different void volume were used in this experiment. It shows that the PD pattern could be classified into five stages and a great diversity in the first four stages is observed. The larger void volume leads to larger PD magnitude. The computer numerical simulation model which is based on a physical discharge process was used and the causes of PD pattern change were interpreted by comparison with computer numerical simulation results. The initial values and change tendency of gas pressure and surface conductivity were determined through experiment. The model parameters in different stages have been studied as well as the insight into the physical changes in the void during electrical aging. The results provide rules for the identification of the electrical aging stage through the partial discharge measurements.

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Section: Introductionmentioning

confidence: 99%

Measurement and simulation of partial discharge in oil impregnated pressboard with an electrical aging process

Yao

et al. 2009

Meas. Sci. Technol.

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“…The surface discharge time constant τ s in a void is proportional to surface conduction, hence the In this context, the charge memory effect may be related to the ability to create and sustain of the E q field. The exposure of the void walls to discharges leads to surface erosion and degradation [1,7,13,17,19]. It was shown by [3] that the leakage current in the void in polyethylene was negligibly small in untreated specimens when compared with ones subjected to discharges.…”

Section: Discharge Process In Voidmentioning

confidence: 99%

“…With dashed lines processes for high and low surface conductivity are marked. The long term exposure of the void walls to discharges leads to surface degradation and broadening of so-called effective discharge area in bigger voids [7,13,20,21]. This effect is impacting additionally the stochastic PD pattern modulation and being a possible origin of bulk dielectric penetration.…”

Section: Discharge Process In Voidmentioning

confidence: 99%

“…Partial discharge exposure in gaseous voids within solid dielectrics leads to changes in surface conditions, such as roughness or morphology, as well as in physical properties, such as charge accumulation and transport, surface and bulk conductivity. Surface conductivity influences the decay of deposited charges and hence the long term inception conditions in a void [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Determination of Surface Erosion Degree inside Dielectric Void Subjected to Partial Discharges

Florkowski

2018

Acta Phys. Pol. A

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Novel approach to determine degree of surface erosion inside void subjected to partial discharges is presented. The deterioration of the void wall is associated with a time decay of accumulated charges, which reflects changing surface conductivity. The introduced methodology is based on non-continuous, chopped partial discharges sequencing. It can allow to estimate post discharge charge decay in the void, calculated as a time constant of the decay of internal accumulated electric field from deposited charges. The chopped sequence consists of multiple series of packets containing the base waveforms, followed by the defined delay time between subsequent packets. Train of base waveforms is applied to a dielectric material and as a whole epoch repeated within given measurement time. Main focus is on the internal mechanism inside voids, especially with respect to void surface conditions and charge decay phenomena. The experiments were carried out in a gaseous voids in polyethylene filled with air at atmospheric pressure. Presented method reveals impact of deposited charges creating an internal field, which interplays with superimposed external electric field in terms of the discharge inception conditions. It was demonstrated that this methodology can reveal quantitatively charge dynamics based on partial discharges phase-resolved pattern and applied analytics. Time constant of deposited charge decay in void was estimated based on two measurements with different fill factors.

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“…Unavoidable insulation defects such as voids in insulation equipment cause partial discharge (PD) which then leads to degradation of the insulation system and even results in insulation failure [1,2]. Although the behavior of discharges in voids at an alternating-current (ac) voltage has been well investigated, few studies so far have been focused on discharges at impulse voltages even though electrical equipment has to undergo rigorous impulse voltage tests [3][4][5][6][7]. Is the PD detection at impulse voltages more effective in diagnosing defects and how do impulse voltage waveforms influence the PD characteristics?…”

Section: Introductionmentioning

confidence: 99%

Partial discharge characteristics and mechanism in voids at impulse voltages

Zhao

Yao

Guo

et al. 2011

Meas. Sci. Technol.

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Partial discharge (PD) characteristics and mechanism in artificial cavities in an epoxy plate have been investigated for different void dimensions and impulse voltage waveforms. A differential measurement system was developed in order to detect PD current pulses effectively. Experimental results showed that the 50% probability PD inception voltage (PDIV50) increases initially as the cavity diameter decreases at constant depth for double exponential impulses as well as oscillating impulses, but after aging, it becomes independent of the cavity diameter. Moreover, some distinctive characteristics of PD (e.g. main discharge and reverse discharge during the rise and fall phases of the applied voltage) were also investigated. The differences of the PD propagation and the mechanism between double exponential impulses and oscillating impulse were discussed.

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Contribution of surface conductivity to the current forms of partial discharges in voids

Cited by 24 publications

References 13 publications

Measurement and simulation of partial discharge in oil impregnated pressboard with an electrical aging process

Measurement and simulation of partial discharge in oil impregnated pressboard with an electrical aging process

Determination of Surface Erosion Degree inside Dielectric Void Subjected to Partial Discharges

Partial discharge characteristics and mechanism in voids at impulse voltages

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