scholarly journals Prediction of Moisture and Aging Conditions of Oil-Immersed Cellulose Insulation Based on Fingerprints Database of Dielectric Modulus

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1722
Author(s):  
Yiyi Zhang ◽  
Sheng Li ◽  
Xianhao Fan ◽  
Jiefeng Liu ◽  
Jiaxi Li
Keyword(s):  
Low Frequency ◽  
Degree Of Polymerization ◽  
Transformer Oil ◽  
Electrode Polarization ◽  
Insulation System ◽  
Dielectric Modulus ◽  
Aging Conditions ◽  
Fingerprint Database ◽  
Cellulose Insulation ◽  
Potential Tool

Frequency-domain spectroscopy (FDS) is demonstrated to be affected by electrode polarization and conductance behavior in the low-frequency ranges, which causes the unreliable prediction results of transformer cellulose insulation. In order to solve this issue, a fingerprint database based on the dielectric modulus is reported to predict the degree of polymerization (DP) and moisture content of cellulose insulation. In the current work, the relevant fingerprints that characterize the insulation conditions are obtained by studying the dielectric modulus curves of cellulose insulation with various insulation conditions, as well as the DC conductivity of transformer oil. Then, the dielectric modulus fingerprint database is established in the lab, and the accuracy of the reported fingerprint database is later verified. As a potential tool, the dielectric modulus fingerprint database is tested by several samples, and the results demonstrate that the accuracy of this method is more than 80%. In that respect, an interesting discovery of this paper is that the dielectric modulus fingerprint database may be a helpful tool for conditions prediction of the transformer cellulose insulation system.

scholarly journals A Modified Aging Kinetics Model for Aging Condition Prediction of Transformer Polymer Insulation by Employing the Frequency Domain Spectroscopy

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2082 ◽  
Author(s):  
Jiefeng Liu ◽  
Xianhao Fan ◽  
Yiyi Zhang ◽  
Hanbo Zheng ◽  
Zixiao Wang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Frequency Domain ◽  
Degree Of Polymerization ◽  
Kinetics Model ◽  
Model Parameters ◽  
Aging Condition ◽  
Feature Parameter ◽  
Aging Kinetics ◽  
Cellulose Insulation ◽  
Potential Tool

The aging kinetics model is of great interest to scholars since it is capable of describing the variation law between the degree of polymerization (DP) and the aging duration of transformer polymer (cellulose) insulation. However, it is difficult to determine the moisture content inside the transformer polymer insulation without destroying it, so that the model parameters cannot be confirmed. Such limitation greatly restricts its application. It is interesting to note that as long as the moisture content of the transformer polymer insulation could be characterized (replaced) by a certain feature parameter, the above issue will be solved naturally. The existing researches indicate that the Frequency Domain Spectroscopy (FDS) is sensitive to moisture. Consequently, the feature parameter that could characterize the moisture inside transformer polymer insulation (extracted from the FDS curve) can be used to report a modified aging kinetics model, which could perform the aging condition prediction of transformer polymer insulation under various test conditions, including aging duration, aging temperature, and initial moisture. In that respect, the average relative error of prediction results of prepared samples is equal to 7.41%, which reveals that the reported model might be serviced as a potential tool for the aging condition prediction of transformer polymer insulation.

Mineral interfacial processes in the method of induced polarization

Geophysics ◽  
1984 ◽  
Vol 49 (7) ◽  
pp. 1105-1114 ◽  
Author(s):  
James D. Klein ◽  
Tom Biegler ◽  
M.D. Horne
Keyword(s):  
Frequency Domain ◽  
Diffusion Layer ◽  
Electrode Potential ◽  
Rotation Speed ◽  
Low Frequency ◽  
Rotating Disk ◽  
Active Species ◽  
Hydrodynamic Theory ◽  
Electrode Polarization ◽  
Disk Electrodes

A phenomenological laboratory investigation has been conducted of the IP response of pyrite, chalcopyrite, and chalcocite. The technique that was used is standard in electrochemistry and employs rotating disk electrodes. The effect of rotation is to stir the electrolyte and thus to restrict the maximum distance available for diffusion of electroactive aqueous species. For high rotation speed and low excitation frequencies, the mean diffusion length exceeds the thickness of the diffusion layer. The net effect is to reduce the electrode impedance at low frequency. The thickness of the diffusion layer and thus the impedance at low frequency can be controlled by the rotation speed. Measurements using rotating disk electrodes have been conducted in both the time domain and the frequency domain. For both pyrite and chalcopyrite, the results were the same: no dependence on rotation was observed. For frequency domain measurements with chalcocite, a strong dependence on rotation was observed. The interpreted diffusion layer thickness was found to depend on rotation speed to the [Formula: see text] power, in agreement with results predicted by hydrodynamic theory. The results of this study imply that there are two physical processes responsible for electrode polarization in the IP method. For chalcocite and perhaps other related copper sulfide minerals, the probable mechanism is diffusion of copper ions in the groundwater. In case, the phenomenon is correctly described by the Warburg impedance. Chalcocite’s distinctive response is thought to be related to its forming a reversible oxidation‐reduction couple with cupric ions in solution. No other common sulfide mineral forms a reversible couple with its cations in solution. For the other minerals of this study, the lack of dependence on rotation implies that diffusion of active species in the electrolyte is not the controlling process. Possible alternate mechanisms include surface controlled processes such as surface diffusion or adsorption phenomena. Ancillary data obtained during this study indicate the interface impedance of chalcopyrite is proportional to the electrode potential which in turn can be controlled by rotation speed, electrolyte composition, or application of an external dc current or voltage. This implies that the surface concentration of active species is dependent on electrode potential.

Electrode polarization and unusual magnetodielectric effect in a transformer oil-based magnetic nanofluid thin layer

2017 ◽  
Vol 146 (1) ◽  
pp. 014704 ◽  
Author(s):  
Michal Rajnak ◽  
Bystrik Dolnik ◽  
Juraj Kurimsky ◽  
Roman Cimbala ◽  
Peter Kopcansky ◽  
...  
Keyword(s):  
Thin Layer ◽  
Transformer Oil ◽  
Electrode Polarization ◽  
Magnetic Nanofluid ◽  
Magnetodielectric Effect

Condition prediction for oil-immersed cellulose insulation in field transformer using fitting fingerprint database

2020 ◽  
Vol 27 (1) ◽  
pp. 279-287 ◽  
Author(s):  
Jiefeng Liu ◽  
Xianhao Fan ◽  
Yiyi Zhang ◽  
Hanbo Zheng ◽  
Chaohai Zhang
Keyword(s):  
Fingerprint Database ◽  
Cellulose Insulation

scholarly journals PCBs Contamination among Distribution Transformers in the Kathmandu Valley

2015 ◽  
Vol 4 (1) ◽  
pp. 16-29 ◽  
Author(s):  
Ruska Kattel ◽  
Bhupendra Devkota
Keyword(s):  
Low Frequency ◽  
Soil Surface ◽  
Transformer Oil ◽  
Kathmandu Valley ◽  
Electrical System ◽  
Tonal Noise ◽  
Distribution Centre ◽  
Distribution Transformers ◽  
The Status ◽  
Crucial Part

Transformer is the crucial part in any electrical system, however there are many risks associated with its use. Thus this study was focused on assessing the status of PCBs contamination and distribution of transformers in Distribution Centre-North of the Kathmandu valley along with PCBs contamination in them. Each transformer within the study area was closely observed to obtain information about all transformers. The dielectric oil samples from the transformers were collected, safely stored and analyzed in Test Kits (L2000DX Chloride Analyzer System, recommended by UNEP). Among 111 samples of transformer oil analyzed, 4 transformers were found PCBs contaminated and they were manufactured before 1990s. The total amount of PCBs contaminated transformer oil in these transformers was 479.6 Kg. Seven transformers were found leaking, four transformers located at residential area were found emitting a low frequency tonal noise, two transformers were located within school compound, nine transformers were located near water body and around 1.44 square meters of soil surface was found contaminated by transformer oil. Though there is no way to eliminate all the risk and consequences of operating oil filled transformers, scientific distribution and proper handling could be the reasonable approaches to reduce the risks.DOI: http://dx.doi.org/10.3126/ije.v4i1.12175International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, Page: 16-29

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