On the degradation of insulating materials withstanding electrical stress

Mayoux, C.

doi:10.1109/ceidp.2000.885217

Cited by 12 publications

(5 citation statements)

References 46 publications

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“…The resultant oil-born soluble and insoluble decay products inevitably contribute to the deterioration of the internal insulation of windings. This must probably be the reason why C. Mayoux came to the conclusion that the gassing of oil is a self-sustained process [9]. …”

Section: Free Radicalsmentioning

confidence: 99%

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On the stability of mineral insulating oils under electrical stress

Fofana

Bouaicha

Farzaneh

et al. 2009

2009 IEEE Electrical Insulation Conference

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There is a general agreement that in service conditions the quality of mineral insulating oils gradually deteriorates under the impact of electrical, thermal and chemical stress. It is also widely accepted that only the incipient electrical failures such as hot spots and partial discharges are responsible for the gassing of oil. Nevertheless, the relationship between the cause and the symptoms of paper insulation deterioration is not clearly understood. This article intends to show that the gassing of oil is a more complex phenomenon. It provides experimental evidence that the chemical composition of hydrocarbon blend and the oil born decay products are also contributing factors to oil gassing.

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Section: Free Radicalsmentioning

confidence: 99%

“…Since its ground state is a triplet, the first two excited states of oxygen are singlet states that have very long lifetimes [5,9,10]. According to Henry's law, the amount of gases dissolved in mineral oil is dependent upon the partial pressure of existing gases above the surface.…”

Section: Chemical Stressmentioning

confidence: 99%

On the stability of mineral insulating oils under electrical stress

Fofana

Bouaicha

Farzaneh

et al. 2009

2009 IEEE Electrical Insulation Conference

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“…Since its ground state is a triplet, the first two excited states of oxygen are singlet states that have very long lifetimes [5][6][7]. According to Henry's law, the amount of gases dissolved in mineral oil is dependent upon the partial pressure of existing gases above the surface.…”

Section: Background On Oxydation and Decay Productsmentioning

confidence: 99%

The gassing tendency of various insulating fluids under electrical discharge

N’cho¹,

Fofana²,

Béroual³

et al. 2011

IEEE Trans. Dielect. Electr. Insul.

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Since gas evolvement deteriorates the dielectrical properties of insulating fluid, its ability to resist decomposition under electrical discharge is of paramount importance for the safety of power transformers under operating conditions. In this paper, a series of experiments have been performed under electrical discharge according to ASTM D6180. Various insulating fluids were considered. The samples include minerals oils, synthetic and natural esters, and silicone fluid. The results indicate that the gassing tendency of natural esters is much lower than their counterparts. No significant differences between synthetic esters and silicone fluid were observed. Severely hydrotreated and hydrocracked oils indicate a higher gassing tendency. It is also shown that service-aged oil gassing tendency decreases with reclamation passes. The reclamation of service aged oil by three commercially available Fuller's Earth (FE) showed a declined gassing tendency when FE helped reducing the DDF and turbidity. In addition, the theoretical premises that, oil born decay products contribute to the oil gassing, is experimentally confirmed under laboratory conditions. Extended stability test (3 times longer than the standard specification) also provide convincing evidences that each brand of mineral insulating oil might contain a limited amount of unstable hydrocarbons and volatile compounds. This finding indicates that when in service conditions these are gradually decomposed, the gassing tendency should go down.

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“…The gassing tendency of an insulating liquid is defined as the chemical decomposition of certain vulnerable hydrocarbons under the impact of electrical stresses [15,16]. In the present work, after five hours of continues electrical discharge at 9 kV, a liquid sample of 30 mL is sampled with a syringe from the discharge test cell.…”

Section: Dissolved Gas Analysismentioning

confidence: 99%

Influence of Aging on Oil Degradation and Gassing Tendency for Mineral oil and Synthetic Ester under Low Energy Discharge Electrical Faults

2020

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The intent of this work is to understand the influence of low energy discharge electric faults in mineral oil and synthetic esters on liquid degradation and gassing tendency at different aging conditions (based on acidity values). A low energy discharge electric fault has been created by continuous discharge of 9 kV for five hours on the liquid surface using a suitable laboratory setup. Liquid degradation is reported by adopting UV spectroscopy, turbidity, and particle counter measurements. The gassing tendency is understood by dissolved gas analysis using Duval’s triangle and Duval’s pentagon methods for mineral oil and non-mineral oils accordingly. It is observed that the influence of low energy discharges on liquid degradation is higher in mineral oils than synthetic esters. The fault gasses in mineral oil are involved with electrical and thermal faults accompanied by stray gassing whereas only partial discharge activity is noticed for synthetic esters. Importantly, the existence of low energy discharge faults like corona discharges will involve a generation of excess high molecular weight products as compared to low molecular weight products that are soluble in liquid volume.

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On the degradation of insulating materials withstanding electrical stress

Cited by 12 publications

References 46 publications

On the stability of mineral insulating oils under electrical stress

On the stability of mineral insulating oils under electrical stress

The gassing tendency of various insulating fluids under electrical discharge

Influence of Aging on Oil Degradation and Gassing Tendency for Mineral oil and Synthetic Ester under Low Energy Discharge Electrical Faults

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