Influence of Temperature and Pressure on Conduction Currents in Transformer Oil

Megahed, I.Y.; Zaky, A. A.

doi:10.1109/tei.1969.299079

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…By choice, we can assign useful ranges of stoichiometries for the two electrode materials of 0.61 for the coke and 0.83 for the lithium manganese oxide. These stoichiometric ranges correspond to the following electrochemical processes charge C, + 0.61Li + 0.61e Li061C5 [2] discharge charge LiMn2O4 0.83Li + 0.83e + Li0 17Mn2O4 [3] discharge The active mass ratio needed to cycle these two materials in the manner shown here is equal to 1.85. This is calculated by using the theoretical capacities of both positive and negative electrode (C÷ = 148 mAh/g and C = 372 mAh/g), equal to F divided by the molecular weight of the electrode material in its discharged state.…”

Section: Capacity Jyjmentioning

confidence: 99%

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Capacity Fade Mechanisms and Side Reactions in Lithium‐Ion Batteries

Arora

White

Doyle

1998

J. Electrochem. Soc.

1,263

1,018

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The capacity of a lithium-ion battery decreases during cycling. This capacity loss or fade occurs due to several different mechanisms which are due to or are associated with unwanted side reactions that occur in these batteries. These reactions occur during overcharge or overdischarge and cause electrolyte decomposition, passive film formation, active material dissolution, and other phenomena. These capacity loss mechanisms are not included in the present lithium-ion battery mathematical models available in the open literature. Consequently, these models cannot be used to predict cell performance during cycling and under abuse conditions. This article presents a review of the current literature on capacity fade mechanisms and attempts to describe the information needed and the directions that may be taken to include these mechanisms in advanced lithium-ion battery models. lnfroduction The typical lithium-ion cell'-3 (Fig. 1) is made up of a coke or graphite negative electrode, an electrolyte which serves as an ionic path between electrodes and separates the two materials, and a metal oxide (such as LiCoO2,

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Section: Capacity Jyjmentioning

confidence: 99%

“…The reduction reactions for the salts are as follows 2 The performance of graphite electrodes is unaffected by small amounts of water (100 to 300 ppm) present in the solvents. For higher concentrations of water.…”

Section: Overcharge Protection7476mentioning

confidence: 99%

Capacity Fade Mechanisms and Side Reactions in Lithium‐Ion Batteries

Arora

White

Doyle

1998

J. Electrochem. Soc.

1,263

1,018

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“…It has been suggested (Megahed and Zaky 1969) that emitted electrons may alternately be trapped and thermally untrapped in relatively shallow traps in the liquid, so that electrons move through the liquid by a hopping mechanism. As the temperature is increased, the probability of thermal untrapping increases so that electrons remain free for longer times.…”

Section: Discussionmentioning

confidence: 99%

High-field conductivity in liquid paraffin

Megahed¹,

Nosseir²

1975

J. Phys. D: Appl. Phys.

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The paper gives experimental results showing the dependence of conduction currents and current pulses in liquid paraffin on temperature, dissolved gases, aromatic additives and hydrostatic pressure. The results support the theory that a gaseous phase is evolved at some stage in the breakdown of hydrocarbon liquids. The gaseous phase is most likely hydrogen bubbles produced by dissociation of the liquid molecules by energetic electrons.

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“…Due to the small damage of the insulating material the local electrical discharge has occurred between the coil to coil, or coil to ground connection [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In this work, the arc ageing is performed by using a needle-flat electrode placed horizontally inside the dielectric test cell.…”

Section: Degradation Of Insulating Oil Due To Arc Ageingmentioning

confidence: 99%

“…Beyond the withstand label of the temperature the transformer oil is gradually degraded and the insulating property of the oil is lost due to the thermal effect [17,18]. In real life, the heating of the insulating oil is caused by many phenomena such as over loading, poor connection on tap changers, loose connection on a bushing or a ground strap, circulating current due to an unintendent core ground or other anticipated heat source and improper cooling system.…”

Section: Degradation Of Insulating Oil Due To Thermal Ageingmentioning

confidence: 99%