Effect of polarity and gap length on the breakdown characteristics of mineral oil for non-uniform fields

Zaky, A. A.; Nosseir, A.; Megahed, I.Y.; Evangelou, C

doi:10.1088/0022-3727/9/8/003

Cited by 13 publications

(2 citation statements)

References 5 publications

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“…Things become even more complicated because far too often there are bubbles and minute foreign particles in an oil gap [51,61]. Especially, non-uniform electrode arrangements may indicate the breakdown streamer mechanism in an oil gap [66,67].…”

Section: Electrodesmentioning

confidence: 99%

A Short Review of Some of the Factors Affecting the Breakdown Strength of Insulating Oil for Power Transformers

Danikas

Sarathi

Morsalin

2020

Eng. Technol. Appl. Sci. Res.

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The present short review investigates some of the factors affecting the breakdown strength of transformer oil. Factors such as the conditioning effect, effect of oil flow, influence of impurities, type of applied voltage and electrode configuration and geometry are further discussed. It should be noted that this review does not discuss the effect of factors such as area, volume and capacitance. Velocity, impurities, electrodes’ shape and the type of applied voltage are among the factors documented to have a significant effect on breakdown strength.

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Section: Electrodesmentioning

confidence: 99%

A Short Review of Some of the Factors Affecting the Breakdown Strength of Insulating Oil for Power Transformers

Danikas

Sarathi

Morsalin

2020

Eng. Technol. Appl. Sci. Res.

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“…In some transformers, a gap length as much as 3.2 mm is created. Since the PD occurrence rate decreases as the length of the oil gap decreases [15,16], the expected maximum oil gap length of 3.2 mm was adopted in this experiment to investigate the possibility of the PD occurrence in a real transformer.…”

Section: Experimental Modelmentioning

confidence: 99%

Partial discharge observation of a complex insulation structure model and residual space charge characteristics investigation under repeated lightning impulses

Ichimura

Rokunohe

2021

IET Science Measure & Tech

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In this research, the authors concentrated on a rarely studied part in the power transformer's insulation structure: the connection part of radial and axial spacers. An experimental model was constructed to simulate this part. It was experimentally observed that the partial discharge starting in the oil gap created by the axial and radial spacers. Characteristics of the abovementioned partial discharge under repeated lightning impulses were also investigated. A longer interval time seemed to accelerate the insulation property deterioration of the constructed model, which is contrary to those reported in other studies. It was because that the partial discharge occurrence was prevented by the residual space charge at the surface of oil/insulation if the time interval of the repeated impulses was not long enough. Therefore, it is proposed that a long enough interval time or a polarity test is expected in the factory test to exclude the influence of the residual space charge and understand the real insulation property of power transformers.

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Charge injection between concentric cylindrical electrodes

Zahn

Chatelon

1977

Journal of Applied Physics

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The transient electric field and space-charge distributions and terminal voltage-current characteristics are solved for drift-dominated unipolar ion conduction between concentric cylindrical electrodes. Special attention is directed to comparing solutions with charge injection from the inner and outer electrodes. As in past work with parallel-plate geometries, the method of characteristics is used to convert the governing partial differential equations into a set of first-order ordinary differential equations which are easily numerically integrated by the Runge-Kutta method. For current-source excitations the equations can be integrated exactly. Special cases examined include the charging transients to a step voltage or current excitation from rest under space-charge-limited conditions and the discharging transients for systems in the dc steady state which are instantaneously open or short circuited.

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Effect of polarity and gap length on the breakdown characteristics of mineral oil for non-uniform fields

Cited by 13 publications

References 5 publications

A Short Review of Some of the Factors Affecting the Breakdown Strength of Insulating Oil for Power Transformers

A Short Review of Some of the Factors Affecting the Breakdown Strength of Insulating Oil for Power Transformers

Partial discharge observation of a complex insulation structure model and residual space charge characteristics investigation under repeated lightning impulses

Charge injection between concentric cylindrical electrodes

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