Conduction current pulses in transformer oil

Megahed, I.; Tropper, H.

doi:10.1088/0022-3727/4/3/314

Cited by 13 publications

(4 citation statements)

References 12 publications

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“…Indeed, bubble behaviour in liquids and the parameters governing such phenomenon have been widely discussed in [26, 27]. The required electric fields are relatively low, when the applied stress exceeds a few hundreds of thousands V cm −1 [28]. Pulsed currents recordings in liquid dielectrics have been associated to partial discharges within gas bubbles created or pre‐existing in the liquid bulk.…”

Section: Isothermal Charging Currentsmentioning

confidence: 99%

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Moisture and electrical discharges effect on naphthenic mineral oil properties

Toudja

Moulai

Nacer

et al. 2014

IET Science, Measurement & Technology

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The physicochemical properties of three transformer mineral oils of different levels of degradation, resulting from exposure to moisture and electrical discharges, are investigated. The first oil is new and untreated whereas the second is taken from a transformer after one year of normal operation; and the third oil is extracted from a 15-year-old operating transformer. The considered parameters are breakdown voltage, dielectric constant ε r , dissipation factor (tan δ) and resistivity. Isothermal charging currents have also been measured under dc for long application times. It is shown that the physicochemical characteristics present major differences depending on the considered oil sample. An easy method enabling to determine the water solubility in oil is proposed; this method is based on the measurement of oil resistivity. To validate a part of the results obtained in laboratory, measurements on an on-load operating transformer have also been achieved. These show that the properties of oils with dissolved water in laboratory are similar to those of oils with really dissolved water inside operating transformers.

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Section: Isothermal Charging Currentsmentioning

confidence: 99%

“…Pulsed currents recordings in liquid dielectrics have been associated to partial discharges within gas bubbles created or pre‐existing in the liquid bulk. It is suggested that the pulses are because of the ionisation of microscopic gas bubbles by electrons emitted at the cathode [28].…”

Section: Isothermal Charging Currentsmentioning

confidence: 99%

Moisture and electrical discharges effect on naphthenic mineral oil properties

Toudja

Moulai

Nacer

et al. 2014

IET Science, Measurement & Technology

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“…Also, the amplitudes and repetition rates of the conduction current bursts have been the subject of numerous statistical studies in recent years (Megahed and Nosseir 1969, Nosseir and Megahed 1970, Megahed and Tropper 1971, Nosseir 1973.…”

mentioning

confidence: 99%

General hypergeometric systems of equations and series of hypergeometric type

Gel'fand¹,

Граев²,

Retakh³

1992

Russ. Math. Surv.

185

244

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Observations were made of the temporal variations of conduction currents through point-to-sphere and sphere-to-sphere gaps of insulating oil and of n-hexane under high direct voltages. Current bursts were distinguished from the normal fluctuations of the quasi-steady current component. Long-duration bursts were similar to some previous observations, but many short bursts had the polarity opposite to that of the quasi-steady component.

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“…Previous observations of conduction currents under direct voltages have usually been of their average values and their variations with voltage and with physical conditions (Singh et al 1972). Also, the amplitudes and repetition rates of the conduction current bursts have been the subject of numerous statistical studies in recent years (Megahed and Nosseir 1969, Nosseir and Megahed 1970, Megahed and Tropper 1971, Nosseir 1973.…”

mentioning

confidence: 99%