Electrostatic Charging Tendency of Transformer Oils

Oommen,; Petrie,

doi:10.1109/mper.1984.5525916

Cited by 11 publications

(19 citation statements)

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“…The EPRI related work reported by Oommen and Petrie [33] and by Oommen [38,39] concentrated on ECT measurements in new oils from various suppliers. The parameters considered were moisture content, presence of metal contamination, presence of inhibitors, temperature, and time of aging (oxidation).…”

Section: Ministatic Charge Tester Datamentioning

confidence: 99%

“…However, the results of research indicate that the understanding of the impact of the production process on ECT values should be given higher priority. In general, very little is known by researchers of the chemistry of the oils investigated and studies that combined ECT with chemical analysis of both basic (hydrocarbons) and trace (polar in particular) compounds have not provided clear answers [33,53]. No explanation has ever been provided for the differing ECT levels in apparently similar new oils, in relation to either their aromatic hydrocarbon content or any other criteria.…”

Section: Effect Of the Oil Refining Processmentioning

confidence: 99%

“…However, in research models employed for ECT measurements, the dependence of charging tendency on temperature did not always show a maximum. N o maximum was found in transformer oils, at any flow rate, either during the ministatic charger experiments [33,39,43] or in model duct and pipe installations [53,109] and rotating models [121] including spinning discs [123]. However, a maximum was found for a transformer oil when the ministatic tester had a glass filter [127].…”

Section: Effect Of Temperaturementioning

confidence: 99%

“…Aging of oil results in the presence of oxidation products influencing ECT levels [go], It was demonstrated [5,33,53,81,82,89], that an increase in the degree of aging causes transformer oil to change ECT. Severe oxidative aging caused ECT to rise [go] in uninhibited oils.…”

Section: Effect Of Agingmentioning

confidence: 99%

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Electrostatic charging in transformer oils. Testing and assessment

Sierota

Rungis

1994

IEEE Trans. Dielect. Electr. Insul.

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Section: Ministatic Charge Tester Datamentioning

confidence: 99%

Section: Effect Of the Oil Refining Processmentioning

confidence: 99%

Section: Effect Of Temperaturementioning

confidence: 99%

Section: Effect Of Agingmentioning

confidence: 99%

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Electrostatic charging in transformer oils. Testing and assessment

Sierota

Rungis

1994

IEEE Trans. Dielect. Electr. Insul.

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“…One expedient recognizes the oil as the common element that is most readily replaced, and seeks to correlate flow-induced failure with, and appropriately modify, some oil property. A suggested (2) property is the so-called "charging tendency," which measures the charge separated as a sample volume flows through a paper filter, and which is found to be sensitive to handling and trace chemicals. While it would be a welcome development to find that an identifiable range of charging tendency presages failure in existing units, and that this property can be controlled, there would remain no rational basis for anticipating safe operation of planned units when increased heat transfer capacity is pursued.…”

Section: Section Of the Insulating Tube Showing Typical Profilesmentioning

confidence: 99%

Electrification by liquid dielectric flow

Gasworth

1986

Conference on Electrical Insulation &Amp; Dielectric Phenomena - Annual Report 1986

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The charging of insulating surfaces by the flow of semi-insulating liquids is investigated with a view towards identifying ways to forestall insulation failure in liquid-cooled power distribution equipment. Both fully developed and fully mixed turbulent flows are considered, the former as a model for the flows in insulating tubes, the latter approximating conditions in certain practical elements such as pumps and expansion regions. Models are developed for the space-time evolution of charge and electrical stress that emphasize the interplay between electrokinetic charge generation, convective transport, ion diffusion and self-precipitation, and conduction driven by the generated fields themselves.Experiments are designed to allow measurement of the currents influent to the insulating tube or expansion region, and either the accumulating surface charge or the generated electric field. Apart from the imposed flow conditions, the liquid conductivity is controlled by a commercial antistatic agent, while the external configuration of conductors is prescribed with an awareness of the contribution of external image charges to the generated fields. Results indicate that significant electrical stresses stem from the transfer of a net charge to the flow upstream of the insulating element, and migration of the entrained ions in a space charge field that is predominantly normal to the the insulating surface. Leverage over the flow-induced stresses is afforded by the external conductor configuration, control of bulk and surface conductivities, and control of the influent convection current with a properly designed expansion region inserted just upstream of the insulating element.Physicochemical features of the liquid-insulating solid interface are probed in two supplementary experiments that make use of a multi-phase helical winding around a section of an insulating tube. In the first experiment the flow is imposed and half of the phases are excited with a sinusoidal potential. Convective displacement of the resulting standingwave perturbation in the entrained volume charge density is detected as an imbalance in the currents carrying perturbation image charge to two of the unexcited phases. The response is interpreted in terms of the undisturbed convection current, the surface conductivity, and the conductivity gradient at the interface. In the second experiment, the flow is induced by a traveling-wave excitation of the winding with the objective of investigating the charge injection process at the same interface. ACKNOWLEDGEMENTSWith the fresh perspective that comes from extending my contacts outside of the Continuum Electromechanics Lab, I am struck by the uniqueness and depth of the education I've received, all the more so because so much of it has been shaped by one man, Professor James Melcher. To his credit as an educator, the form of this thesis is as much a product of the careful grounding in fundamentals he has provided over the years, beginning long before this project commenced, as of discussions specific...

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