Experience with capacitive on-line sensors for moisture evaluation in transformer insulation

Atanasova-Höhlein, Ivanka; Koncan-Gradnik, M.; Gradnik, Tim; Cucek, Biljana; Przybyłek, Piotr; Siodła, Krzysztof; Liland, Knut Brede; Leivo, Senja; Liu, Qiang

doi:10.1109/mei.2019.8636102

Cited by 18 publications

(7 citation statements)

References 20 publications

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“…With temperature known to affect oil properties, the temperature difference could culminate in a hysteresis phenomenon affecting the relative saturation (RS) of the oil. This RS hysteresis phenomenon has been documented in [24,25] and will be discussed by referring to Figure 6.…”

Section: Relative Saturation Hysteresismentioning

confidence: 55%

“…At a certain temperature, moisture saturation will always be the same (given the same ageing condition and the type of oil), but the RS could be different as the absolute moisture in oil could vary. This causes the hysteresis phenomenon as noted in [24][25][26].…”

Section: Relative Saturation Hysteresismentioning

confidence: 98%

“…Such a hysteresis process progressively leads to higher absolute moisture and a higher RS in oil particularly after a sustained period (a few days) of high temperature difference [24,25]. The resulting high oil RS implies a lower oil breakdown voltage (lower dielectric strength) [28], that is, higher tendency of dielectric failure.…”

Section: Investigation On Cause Of Failuresmentioning

confidence: 99%

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Failure investigation and asset management of combined measuring instrument transformers

et al. 2020

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Asset management of instrument transformers (ITs) has gained momentum in recent years due to their large population in the network and the potential adverse impacts of their increasing number of failures. This study investigates the failure cause of a family of combined measuring ITs via temperature profile simulations and consideration of moisture migration behaviour in an oil‐impregnated paper insulation system. The temperature difference experienced by an IT, particularly throughout summer, together with a relative saturation hysteresis phenomenon could have caused a lower dielectric strength that led to failures. The study also offers insights into factors influencing the probability of failures through analysis on the lifetime data from both graphical survival function plots and statistical Cox model. In‐service age, operating voltage level and environment appear to have an influence on failure rate.

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Section: Relative Saturation Hysteresismentioning

confidence: 55%

Section: Relative Saturation Hysteresismentioning

confidence: 98%

Section: Investigation On Cause Of Failuresmentioning

confidence: 99%

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Failure investigation and asset management of combined measuring instrument transformers

et al. 2020

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“…The constraint of the KFT method is that collecting the paper sample for the test from objective equipment is nearly impossible unless the equipment is scrapped and overhauled. Unlike insulation paper, insulating oil can be practically extracted and the moisture content in oil (MCO) can also be measured by KFT or oil humidity probe [9]. Therefore, an alternative to estimate MCP is to back-calculate it from MCO based on adsorption isotherms [10].…”

Section: Introductionmentioning

confidence: 99%

A Circuital Model-Based Analysis of Moisture Content in Oil-Impregnated-Paper Insulation Using Frequency Domain Spectroscopy

Feng

2020

IEEE Access

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The explicitly numerical or well-defined correlations between the dielectrics responses (DRs) and dielectric essences of oil-impregnated paper (OIP) insulation have not been fully understood yet. As a result, it is rather difficult to quantitatively diagnose the critical insulation condition, like determining moisture content in insulation paper (MCP) of power equipment only using electrical-based techniques such as frequency domain spectroscopy (FDS). To obtain MCP value, from a new perspective of parametric study on the circuital DR equivalence of OIP insulation-extended Debye model (EDM), the present contribution introduces a novel approach by exploring the pattern when EDM parameters vary with MCP and temperatures T . Further, mathematical correlations are developed between sensitive R-C values and MCP-T values. On the above analysis, small-scale physical models of real-life transformer bushings were prepared as test samples. Their OIP condenser bodies were artificially absorbed different controlled quantities of moisture and conditioned at different temperatures to record corresponding FDS results. Then a hybrid genetic algorithm combined with the Levenberg-Marquardt algorithm was proposed to estimate the EDM parameters by fitting the measured FDS data. Sensitive parameters therein were identified using subspectrum decomposition and formulated with MCP-T values so that a reliable moisture content estimation can be achieved once the testing temperature and FDS recordings of an insulation body are known.INDEX TERMS Oil-impregnated-paper insulation, moisture, extended Debye model, frequency domain spectroscopy.

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“…5.3 shows the AC BV vs the absolute moisture content of the fluid's samples for all the samples included in the study including a tendency line for each fluid. A Boltzman model was considered to obtain the adjustment curves in agreement with the recommendation of CIGRE WG D1.52[116].…”

mentioning

confidence: 99%

Analysis of Water Solubility in natural-ester based nanodielectric fluids

Perez

García

Primo

et al. 2019

2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)

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Una tesis doctoral viene firmada por una sola persona, pero hay mucha gente que de un modo u otro ha participado en que esta sea posible, por eso quiero agradecérselo a todas esas personas.En primer lugar, quiero expresar mi más sincera gratitud a mis tutores Dr. Juan Carlos Burgos y Dra. Belén García, por darme la oportunidad de realizar mi tesis doctoral con ellos. Su amplio conocimiento y su nivel de esfuerzo e implicación son inestimables para la finalización de este trabajo. Desde un primer momento creyeron en mi y me han ayudado en todo momento durante este recorrido de más de cuatro años. Gracias.También quiero aprovechar la oportunidad para agradecer a la Universidad Carlos III de Madrid la oportunidad que brinda ofreciendo los contratos predoctorales para poder cursar una tesis doctoral formándonos, además, como profesores. Así mismo, quiero agradecer al resto de personal del departamento de Ingeniería Eléctrica, especialmente al Dr. Guillermo Robles y al Dr. Juan Manuel Martínez con los que he compartido congresos y buenos momentos y a Cristina Vega por su buen humor todas las mañanas.Además, en el plano profesional tengo que dar mi gratitud a los profesores

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Experience with capacitive on-line sensors for moisture evaluation in transformer insulation

Cited by 18 publications

References 20 publications

Failure investigation and asset management of combined measuring instrument transformers

Failure investigation and asset management of combined measuring instrument transformers

A Circuital Model-Based Analysis of Moisture Content in Oil-Impregnated-Paper Insulation Using Frequency Domain Spectroscopy

Analysis of Water Solubility in natural-ester based nanodielectric fluids

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