Anomalous dielectric response of very small quantities of virgin, aged and failed silicone oil

Haidar, Ali; Fothergill, J.C.; Dissado, L.A.; Hopewell, P.

doi:10.1109/tdei.2003.1194120

Cited by 7 publications

(10 citation statements)

References 7 publications

(8 reference statements)

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“…The characteristics of the frequency response of insulating oils shown in this paper have been widely observed by other researchers [13][14][15][16][17][18]. Although the mineral oils tested here have gone through different types of stresses and their original conditions may be different slightly from each other, the frequency responses of these three mineral oils can give an overall picture of the effect of oil conditions when they are fresh, in service for several years and heavily aged that needs to be replaced.…”

Section: Comparation Of the Modified Space Charge Polarization Model supporting

confidence: 65%

“…As the dissociation coefficient of mineral oil increases with temperature, more charge carriers will be generated through ionic dissociation, resulting in a high conductivity if the temperature rises. As reported by other researchers, the relative permittivity of insulting oil changes slightly with the temperature [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The viscosity of mineral oil decreases with temperature.…”

Section: Coelho's Space Charge Polarization Theorymentioning

confidence: 86%

“…Various diagnostic methods have been applied to monitor dielectric changes in insulating liquid over time, no matter these changes are due to thermal, electrical or chemical effects [1][2][3][4]. Dielectric spectroscopy technique, which enables us to gain a bunch of information about the dynamics of bound and mobile charge carriers, has been widely employed in the evaluation of insulating properties of dielectric liquids [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Study of the charge dynamics in mineral oil under a non-homogeneous field

Zhou

Hao

Wilson

et al. 2015

IEEE Trans. Dielect. Electr. Insul.

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The presence of mobile charge carriers can affect the frequency response of complex permittivity of insulating liquid when the frequency is low. It has been found that the experimental results of the complex permittivity of mineral oils are in a good agreement with Coelho's frequency response theory when an extra contribution to the complex permittivity arising from DC conduction is taken into account. It has been reported that small quantity of high mobility charge carriers are responsible for this DC conduction. In our previous work, we have found that if the charge carriers are fast enough so that they can reach the opposite electrode in a cycle, the motion of these fast charge carriers can only contribute to the imaginary part of the complex permittivity under a homogeneous field. In this paper, the polarization induced by the motion of those fast charge carriers under a non-homogeneous field has been studied. It has been found when the field is not high, the total current caused by the drift and diffusion of those fast charge carriers is proportional to the external voltage. A modified space charge polarization theory has been proposed. The frequency dependence of the complex permittivity obtained experimentally has been fitted using this modified Coelho model and compared with our previous simulation. This modified model enables one to gain a better understanding of the frequency response in mineral oil in low frequency regions.

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Section: Comparation Of the Modified Space Charge Polarization Model supporting

confidence: 65%

Section: Coelho's Space Charge Polarization Theorymentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of the charge dynamics in mineral oil under a non-homogeneous field

Zhou

Hao

Wilson

et al. 2015

IEEE Trans. Dielect. Electr. Insul.

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“…When comparing different insulating liquids, they give very similar results for a given electrode arrangement in this type of testing [2]. The aged silicone oil is reported to be more prone to partial discharges, which leads to decreased resistivity [3]. But it is hard to replicate the conditions that prevail in the CSE; and in general, the results of electrical testing are very dependent on the test geometry and conditions.…”

Section: Introductionmentioning

confidence: 86%

Characterization of Silicone Oil used in HV Cable Sealing Ends

Virtanen

George

Andritsch

et al. 2019

NORD-IS

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Existing polymeric cable sealing end (CSE) typically contain silicone oil as an insulating liquid between the cable core and the outside of the CSE. In recent years, a number of performance issues have been identified with silicone oil filled CSEs. To understand the reasons for the observed behavior of silicone oil, a range of characterization methods are reviewed, to allow investigation of the influence of moisture, potential chemical contaminants and the compatibility with CSE materials. The water content of all the oils studied was above the limit given in IEC 60836 (2015) for new silicone oil. There is no significant difference between the moisture content, whether the oil is used in CSE or new. Neither did the Fourier infrared (FTIR) spectroscopic analysis show difference between the oils. Preliminary results from gas chromatography connected to mass spectrometer (GC/MS) clearly show structural differences between unused expired oil and new oil samples particularly that species suspected to be cyclic siloxane appear to be present in the expired sample.

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“…Even small amounts of impurities and residual water alter the electrical properties of silicon liquid [24]- [26]. The aged liquid is more prone to partial discharges, which leads to decreased resistivity [27]. For dielectric liquids, the nature and concentration of impurities control the conductivity and so, the conductivity greatly depends on the sample purity.…”

Section: Conductivitymentioning

confidence: 99%