Low temperature and moisture effects on polarization and depolarization currents of oil-paper insulation

Fofana, I.; Hemmatjou, H.; Farzaneh, M.

doi:10.1016/j.epsr.2009.08.008

Cited by 39 publications

(41 citation statements)

References 10 publications

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“…Therefore, the conductivity both oil and paper (pressboard) increases as the water content increases. This is in accordance with the literature [17,29,31]. Figure 10 shows the depolarization current results of oil-impregnated pressboard specimens with different water contents at 45 • C. It could be seen that the depolarization current values increased significantly and moved upward overall with the increase of water content inside the cellulose pressboard specimens.…”

Section: Water Effect On Pdc Results and Branch Parameters Obtained Fsupporting

confidence: 79%

Study on Quantitative Correlations between the Ageing Condition of Transformer Cellulose Insulation and the Large Time Constant Obtained from the Extended Debye Model

et al. 2017

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Polarization-depolarization current (PDC) measurements are now being used as a diagnosis tool to predict the ageing condition of transformer oil-paper insulation. Unfortunately, it is somewhat difficult to obtain the ageing condition of transformer cellulose insulation using the PDC technique due to the variation in transformer insulation geometry. In this literature, to quantify the ageing condition of transformer cellulose insulation using the PDC technique, we firstly designed a series of experiments under controlled laboratory conditions, and then obtained the branch parameters of an extended Debye model using the technique of curve fitting the PDC data. Finally, the ageing effect and water effect on the parameters of large time constant branches were systematically investigated. In the present paper, it is observed that there is a good exponential correlation between large time constants and degree of polymerization (DP). Therefore, the authors believe that the large time constants may be regard as a sensitive ageing indicator and the nice correlations might be utilized for the quantitative assessment of ageing condition in transformer cellulose insulation in the future due to the geometry independence of large time constants. In addition, it is found that the water in cellulose pressboards has a predominant effect on large time constants.

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Section: Water Effect On Pdc Results and Branch Parameters Obtained Fsupporting

confidence: 79%

Study on Quantitative Correlations between the Ageing Condition of Transformer Cellulose Insulation and the Large Time Constant Obtained from the Extended Debye Model

et al. 2017

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“…The long term depolarization current value of natural ester-paper insulation sample also increases all the time with the ageing. As shown in Figures 4a and 5a, the polarization current values decreases for mineral oil-paper insulation sample aged for 93 days and increases for natural ester-paper insulation sample aged for 30 days may mainly cause by the migration of byproducts between oil and paper [12,28].…”

Section: Pdc Behavior Of Oil-paper Insulation Samples With Different mentioning

confidence: 99%

“…For typical measuring conditions the conductivity of the oil affects the polarization current mainly in a time range t<100 s. A higher oil conductivity leads to a higher initial current. The paper insulation conductivity has dominant effect on its polarization characteristic mainly in the time range t>1000 s [7,23,28]. A higher conductivity of the paper also leads to a higher long term current.…”

Section: Pdc Behavior Of Oil-paper Insulation Samples With Different mentioning

confidence: 99%

“…Greater mobility of charge carriers in the liquid dielectric can be attributed to the higher initial charging currents, after a while, the initial inrush current goes to zero and steady conduction current is recorded due to the lower mobility of charge carriers in the solid insulation [32]. The long term dc conduction current from the polarization measurement normally relates to the paper conductivity, while the short term current magnitude relates to the oil conductivity [7,23,28]. For typical measuring conditions the conductivity of the oil affects the polarization current mainly in a time range t<100 s. A higher oil conductivity leads to a higher initial current.…”

Section: Pdc Behavior Of Oil-paper Insulation Samples With Different mentioning

confidence: 99%

“…The insulation oil and insulation paper conductivity are known to vary with temperature T (in Kelvin) according to the well-known Arhenius relationship [28,34]: (9) where E ac is the activation energy and A is a constant related to ions mobility in the insulation. According to the equation published in [28,35], the conductivity of the oil and paper can be calculated as following: (10) The oil conductivity can be calculated with equation (10) where the i pol (t b ) and i depol (t b ) are the initial values in polarization and depolarization currents [28,35]. The conductivity of the paper can be estimated from the long term values of the polarization and depolarization currents, by replacing the t b with t m , where t m represents the largest value of time that the currents have been measured, in this study t m =5000 s. The oil conductivity and paper conductivity at 40, 55, 70, 85 and 100 °C are shown in Figure 16.…”

Section: Pdc At Different Temperaturesmentioning

confidence: 99%

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Quantitative analysis ageing status of natural ester-paper insulation and mineral oil-paper insulation by polarization/depolarization current

Hao

Liao

Chen

et al. 2012

IEEE Trans. Dielect. Electr. Insul.

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Polarization and Depolarization Current (PDC) technique is an effective tool to assess the condition of oil-paper insulation system in power transformers. So far the PDC behaviors of mineral oil-paper insulation have been widely investigated. However, with the increasing number of transformer choosing natural ester as its insulation oil, it is important to investigate the PDC characteristics of natural ester-paper insulation to see whether the PDC technique can also be used to assess the condition of new insulation system using natural ester in transformers accurately. In this research, natural esterpaper insulation sample and mineral oil-paper insulation sample were subjected to thermally accelerated ageing experiment at 110 °C for 120 days. The PDC characteristics of natural ester-paper insulation sample and mineral oil-paper insulation sample were compared over the ageing process. A new method for assessing the ageing condition of the oil-paper insulation in terms of the depolarization charge quantity was proposed. Results show that the polarization/depolarization current of natural ester-paper insulation sample is higher than that of mineral oil-paper insulation sample with the same ageing intervals. The depolarization charge quantity of both kinds of oil-paper insulation sample is very sensitive to their ageing conditions. There is an exponential relation between the stable depolarization charge quantity of both kinds of oil-paper insulation sample and the degree of polymerization (DP) of paper. The depolarization charge quantity can be used to predict the ageing condition of oil-paper insulation providing the measurement temperature is kept the same.

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Behavior of Ester Liquids Under Various Operating Fault Conditions

Rao¹,

Fofana²,

Loiselle³

2021

Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems

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Low temperature and moisture effects on polarization and depolarization currents of oil-paper insulation

Cited by 39 publications

References 10 publications

Study on Quantitative Correlations between the Ageing Condition of Transformer Cellulose Insulation and the Large Time Constant Obtained from the Extended Debye Model

Study on Quantitative Correlations between the Ageing Condition of Transformer Cellulose Insulation and the Large Time Constant Obtained from the Extended Debye Model

Quantitative analysis ageing status of natural ester-paper insulation and mineral oil-paper insulation by polarization/depolarization current

Behavior of Ester Liquids Under Various Operating Fault Conditions

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