Flow electrification in power transformers: study of a potential remedy

Bourgeois, A.; Paillat, T.; Mortha, Gérard; Moreau, O.; Bertrand, Yves; Touchard, G.

doi:10.1109/icdl.2005.1490114

Cited by 11 publications

(8 citation statements)

References 12 publications

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“…given by [10] r wd = A s B s 4DC 1 (10) 3 Experimental setup Fig. 1 illustrates the experimental setup (flow loop device) that has been built at the University of Poitiers in collaboration with Electricité de France (EDF) to simulate the oil path along the pressboard between transformer windings [9][10][11][17][18][19]. It consists of a stainless steel loop and a sensor as shown in Figs.…”

Section: Dynamic and Static Methods For Calculating Wall Space-chargementioning

confidence: 99%

“…All these measurements analysed the hazard according to the streamed charges, commonly called 'streaming current'. At University of Poitiers, an original sensor was developed to measure the quantity of charges which accumulate into a very well-insulated pressboard [9][10][11][17][18][19]. Only the effects of velocity, temperature and moisture were investigated.…”

Section: Introductionmentioning

confidence: 99%

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Behaviour of electrical double layer under oil flow and voltage application inside a capacitive sensor

Metwally

LeBlanc

Paillat

2015

IET Science, Measurement & Technology

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This study presents an experimental investigation of the behaviour of electrical double layer (EDL) under oil flow and voltage application inside a capacitive sensor. This sensor is incorporated in a closed-loop filled with fresh transformer oil. The sensor configuration allows a potential application for risk assessment. The behaviour of EDL is investigated by recording the streaming and the capacitive current waveforms for grounded and energised middle copper-electrode cases and at different oil-flow velocities and temperatures. The effect of direct and alternating voltage energisation is examined for different wave shapes and frequencies. In addition, the physicochemical reaction coefficient, the wall space-charge density and the accumulated charges inside the sensor are calculated by the static and the dynamic methods. The results are interpreted in terms of EDL evolution, physicochemical reaction at the solid-liquid interface, relaxation time of charges and electron emission from the negatively energised electrode. The results reveal that the calculated wall space-charge density slightly decreases with the increase in the oil-flow velocity, contrary to the physicochemical reaction coefficient. For the case of AC energisation, the results show that there is an innocuous effect of the generated harmonic voltages on the oil-flow electrification phenomenon.

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Section: Dynamic and Static Methods For Calculating Wall Space-chargementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Behaviour of electrical double layer under oil flow and voltage application inside a capacitive sensor

Metwally

LeBlanc

Paillat

2015

IET Science, Measurement & Technology

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“…Moreau et al [19] measured ECT for a flow passing through a filter made of degraded pressboard to show that a degraded surface enhances the charge accumulation and that small amount of additive (i.e., BTA) can reduce ECT. The effect of additive was further studied in [20,21], and by using a flow-loop apparatus, Bourgeois et al [21] addressed the mechanism of the enhancement of ECT in terms of the carboxyl group. Aksamit and Zmarzly [22] also studied the inhibition of flow electrification with the additive 60 .…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Charge Transport in a Space between Concentric Circular Cylinders

Suh

Baek

2014

Journal of Applied Mathematics

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Electrification is one of the key factors to be considered in the design of power transformers utilizing dielectric liquid as a coolant. Compared with enormous quantity of experimental and analytical studies on electrification, numerical simulations are very few. This paper describes essential elements of numerical solution methods for the charge transport equations in a space between concentric cylinders. It is found that maintaining the conservation property of the convective terms in the governing equations is of the uttermost importance for numerical accuracy, in particular at low reaction rates. Parametric study on the charge transport on the axial plane of the annular space with a predetermined velocity shows that when the convection effect is weak the solutions tend to a one-dimensional nature, where diffusion is simply balanced by conduction. As the convection effect is increased the contours of charge distribution approach the fluid streamlines. Thus, when the conduction effect is weak, charge distribution tends to be uniform and the role of the convection effect becomes insignificant. At an increased conduction effect, on the other hand, the fluid motion transports the charge within the electric double layers toward the top and bottom boundaries leading to an increased amount of total charge in the domain.

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“…For maintenance management, the Electric Technology Research Association has proposed a control value (500 pC/ml) as well as measurement cycles and other parameters [1]. Recently, there have been reports of pronounced static (streaming) electrification in aged transformers caused by deterioration of both insulating oil and solid insulators [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Influence of various compounds on electrostatic charging tendency in insulating oil

Okabe

Kotoh

Tsuchie

et al. 2011

Electrical Engineering Japan

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SUMMARYThe influence of various compounds on the increase of the electrostatic charging tendency (ECT) in insulating oil was investigated. Sulfide compounds, which are contained in new mineral oil, are identified for the first time as the original materials involved in the increase of the ECT. This is verified by heating tests of alkylbenzene with the addition of various compounds. Coexistence with copper and injection of oxygen enhance the increase of the ECT. Some sulfide and sulfoxide compounds increase the ECT markedly. On the other hand, the influence of sulfones, which are oxidation products of sulfoxides, is negligible. Although sulfonic acids, which are oxidation products of sulfones, markedly increase the ECT, the polarity is reverse. Thus, the ECT is influenced by the kinds and the molecular structures of additive sulfur compounds. The influence of nitrogen compounds and that of oxygen compounds are confirmed to be smaller than that of sulfur compounds. Since the amounts of nitrogen compounds and oxygen compounds are much smaller than those of sulfur compounds in mineral insulating oils, the influence of these compounds is considered negligible. Since the ECT of oils with the addition of sulfides or sulfoxides increases after heating, the other compounds should be created from these compounds that increase the ECT directly. Thus, the increase of the ECT is mostly caused by the oxidation of sulfides, which creates sulfoxides. Then certain compounds, which directly increase the ECT, are created from sulfoxides. If sulfones or sulfonic acids are created by the oxidation of sulfoxides, the ECT decreases because of the influence of these compounds on the ECT. It is most likely that some process other than oxidation occurs in the creation of the compounds that increase the ECT directly.

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Flow electrification in power transformers: study of a potential remedy

Cited by 11 publications

References 12 publications

Behaviour of electrical double layer under oil flow and voltage application inside a capacitive sensor

Behaviour of electrical double layer under oil flow and voltage application inside a capacitive sensor

Numerical Study on the Charge Transport in a Space between Concentric Circular Cylinders

Influence of various compounds on electrostatic charging tendency in insulating oil

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