The Analysis of Dielectric Characteristics of Transformer Oil Suffering Ageing Treatment

Jung, Jin-Soo; Lim, Young-Bae; Jung, Jong-Wook; Yi, G. H.; Park, H.Y.

doi:10.1109/icpadm.2006.284310

Cited by 8 publications

(2 citation statements)

References 2 publications

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“…The measured

of insulating liquid with the used λ = 4 mm IDS (

2.28) also agrees with literature values [ 17 , 18 , 28 ]. This would not have been the case for λ = 1 mm and λ = 2 mm due to the measured offset.…”

Section: Resultssupporting

confidence: 89%

“…Standard procedures [ 16 ] prescribes the use of low frequencies between 40 to 62 Hz, leading to very low currents through the IDS and thus reducing the signal. Also, insulating liquids as used in power electronics applications show a low permittivity of 2.1 to 3.5 [ 2 , 17 , 18 ] (c.f. ~80 for water) contributing to a low capacitance that further reduces the signal.…”

Section: Introductionmentioning

confidence: 99%

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A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance

Risos

Long

Hunze

et al. 2016

Sensors

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Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity (ϵr) of insulating liquids. Such liquids used in the power industry exhibit a change in ϵr as they degrade. The IDS ability to measure ϵr in-situ can potentially reduce maintenance, increase grid stability and improve safety. Noise from external electric field sources is a prominent issue with IDS. This paper investigates the novelty of applying a Faraday cage onto an IDS as a 3D shield to reduce this noise. This alters the spatially distributed electric field of an IDS affecting its sensing properties. Therefore, dependency of the sensor’s signal with the distance to a shield above the IDS electrodes has been investigated experimentally and theoretically via a Green’s function calculation and FEM. A criteria of the shield’s distance s = s0 has been defined as the distance which gives a capacitance for the IDS equal to 1 − e−2=86.5% of its unshielded value. Theoretical calculations using a simplified geometry gave a constant value for s0/λ = 1.65, where λ is the IDS wavelength. In the experiment, values for s0 were found to be lower than predicted as from theory and the ratio s0/λ variable. This was analyzed in detail and it was found to be resulting from the specific spatial structure of the IDS. A subsequent measurement of a common insulating liquid with a nearby noise source demonstrates a considerable reduction in the standard deviation of the relative permittivity from σnormalunshielded=±9.5% to σnormalshielded=±0.6%. The presented findings enhance our understanding of IDS in respect to the influence of a Faraday shield on the capacitance, parasitic capacitances of the IDS and external noise impact on the measurement of ϵr.

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“…The measured

of insulating liquid with the used λ = 4 mm IDS (

2.28) also agrees with literature values [ 17 , 18 , 28 ]. This would not have been the case for λ = 1 mm and λ = 2 mm due to the measured offset.…”

Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance

Risos

Long

Hunze

et al. 2016

Sensors

View full text Add to dashboard Cite

show abstract

In-situ aging monitoring of transformer oil via the relative permittivity and DC conductivity using novel interdigitated dielectrometry sensors (IDS)

Risos

Gouws

2019

Sensors and Actuators B: Chemical

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A temperature compensated dielectric test cell for accurately measuring the complex permittivity of liquids

Risos

Long

Gouws

2017

Review of Scientific Instruments

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A measurement of the complex permittivity, ε, of a liquid can give valuable information about the molecular polarizability and dielectric losses. This can be obtained by means of an impedance measurement using a parallel plate test cell. However, highly accurate and precise measurements are challenging, in particular when measuring as a function of temperature. Thermal expansion affects the geometry of a test cell and thus the measured capacitance from which ε is calculated. In this paper, a broadband four-terminal dielectric test cell is presented that is insensitive to temperature fluctuations. This was achieved by means of a cell geometry exploiting the thermal expansion coefficient of different materials. Experimental measurements on the manufactured cell yielded a stable capacitance of 35.322 ± 0.001 pF across 20 °C-90 °C. The capacitance stayed within ±0.01 pF over multiple experimental cycles of cleaning and assembly. A finite element modeling showed a theoretical accuracy in measuring ε better than 99.995%. The measured ε values for a number of standard liquids showed an agreement of 99.7% compared to literature values.

show abstract

The Analysis of Dielectric Characteristics of Transformer Oil Suffering Ageing Treatment

Cited by 8 publications

References 2 publications

A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance

A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance

In-situ aging monitoring of transformer oil via the relative permittivity and DC conductivity using novel interdigitated dielectrometry sensors (IDS)

A temperature compensated dielectric test cell for accurately measuring the complex permittivity of liquids

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