Investigation on the performance of thermally aged natural ester fluid impregnated pressboard material

Amalanathan, A. J.; Sarathi, R.; Harid, Noureddine; Griffiths, Huw; Gautam, Ribhu; Vinu, R.

doi:10.1109/tdei.2020.008872

Cited by 6 publications

(7 citation statements)

References 22 publications

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“…2) TRAP DISTRIBUTION ANALYSIS Figure 6 shows the trap distribution of aged pressboard material which was calculated based on Simmon and Tam's theory. According to the literature, it is concluded that found that trap density can be related to tdV/dt [29], and there could be two peaks (shallow trap and deep trap) linked with the degradation. The trap density (𝑁 𝑡 ) and its demarcation energy (𝐸 𝑡 ) involved in the decay process are calculated as follows:…”

Section: B Surface Potential and Trap Characteristics Of Aged Pressbo...mentioning

confidence: 99%

“…The plasma temperature is high for the unaged specimen indicating its higher strength with the strong glycosidic bonding involved in the cellulose structure. With ageing, the plasma temperature is lowered, which could be related to chemical breakdown of long polymeric chains of cellulose into furanose isomers, anhydrous sugars, and low molecular weight oxygenates [29]. Moreover, it is to be noticed that specimens MO, A3 and D3 showed a marginal decrease in the plasma temperature compared to unaged specimen and hence it could be used as a quantitative parameter to differentiate the ageing involved due to DBDS and Ag2S on the pressboard material.…”

Section: Laser Induced Breakdown Spectroscopymentioning

confidence: 99%

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Impact of DBDS and Silver Sulfide on the Performance of Thermally Aged Mineral oil Impregnated Pressboard Material

et al. 2022

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The corrosive sulfur compounds present in the mineral oil causes the formation of dibenzyl disulfide (DBDS) complex and it can also erode the on-load tap changing selector contacts leading to generation of silver sulfide (AgS2).The present work reports the effect of DBDS and Ag2S concentrations in mineral oil on thermally aged pressboard material. The results demonstrate that surface discharge inception voltage (SDIV) is higher for the aged pressboard specimen. The higher concentrations of DBDS showed a reduction of more than 50% in the magnitude of SDIV compared to its effect with the addition of Ag2S. The surface potential analysis indicates a higher initial potential for the aged specimens with an increased half lifetime. In addition, only deep traps observed on the aged specimens with a slight right shift in its trap energy level. The mechanical strength of aged pressboard specimens with DBDS and Ag2S is understood using tensile testing and simultaneous analysis is captured using Digital Image Correlation (DIC) technique to understand its strain percentage at different areas on the pressboard material during its elongation. The laser induced breakdown spectroscopy (LIBS) analysis is performed to identify the elements responsible for thermal ageing such as carbon, copper and sulfur on the surface of pressboard material. The plasma temperature calculated from sulfur peaks is higher for DBDS aged specimen compared to AgS2 and a linear correlation is observed on the LIBS intensity with ageing duration. Further, the Principal Component Analysis (PCA) is used for its classification on the degradation of pressboard due to the diffusion of both copper and silver sulfide from the mineral oil. The two principal components (PC1 and PC2) provided a higher variance of 99.8% with a clear classification observed between the unaged and aged pressboard specimens due to the addition of both DBDS and Ag2S in mineral oil.

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Section: B Surface Potential and Trap Characteristics Of Aged Pressbo...mentioning

confidence: 99%

Section: Laser Induced Breakdown Spectroscopymentioning

confidence: 99%

Impact of DBDS and Silver Sulfide on the Performance of Thermally Aged Mineral oil Impregnated Pressboard Material

et al. 2022

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“…The optically induced plasma was ignited once the energy of the laser was greater than that of the threshold fluence of the material. To remove ester fluid impregnated on the pressboard material, it was degreased with n‐hexane [10] prior to the analysis of LIBS testing. In the present study, laser was operated at different time delays to vary the energy of the laser beam from 20 to 90 mJ and then focussed at 90° to the EIP material to spot a diameter of 0.5 mm.…”

Section: Experimental Studiesmentioning

confidence: 99%

“…These include acoustic methods [7], electrical methods [8] and physicochemical based methods [9]. Amalanathan et al [10] has studied the performances of EIP material under different temperatures, inferring a higher trap density and conductive mechanisms involved during its ageing process. The surface discharge on the pressboard insulation barrier is considered as one of the major failure modes for large power transformers.…”

Section: Introductionmentioning

confidence: 99%

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Classification of thermal ageing impact of ester fluid‐impregnated pressboard material adopting LIBS

et al. 2021

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This article reports the thermal ageing of ester fluid-impregnated pressboard material along with its performance evaluation using optical emission spectroscopy (OES) and classification using machine-learning algorithms adopting laser-induced breakdown spectroscopy (LIBS). The surface discharge analysis on ester-impregnated pressboard (EIP) is studied using OES and the plasma temperature was evaluated based on the Cu I emission lines which were higher under the negative DC compared with the positive DC and AC voltages. The LIBS analysis was performed on the EIP material operated at different energy levels in order to acquire the optimal energy required to be used for its classification algorithm. The intensity ratio and electron density evaluated from LIBS studies correlated well with the plasma temperature. The lower limit of detection (LOD) calculated based on linear regression analysis for copper peak was around 3.5 times higher than the identification of carbon peak. The machine-learning techniques like principal component analysis and neural network algorithm have been performed on the LIBS spectral dataset in order to classify the ageing of EIP material. Artificial neural network adopting LIBS provided a better classification accuracy on all the aged samples compared with principal component analysis which classified only for the samples aged at higher temperatures.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Degradation Assessment of Ester Liquids

Amalanathan

Sarathi

Harid

et al. 2021

Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems

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Investigation on the performance of thermally aged natural ester fluid impregnated pressboard material

Cited by 6 publications

References 22 publications

Impact of DBDS and Silver Sulfide on the Performance of Thermally Aged Mineral oil Impregnated Pressboard Material

Impact of DBDS and Silver Sulfide on the Performance of Thermally Aged Mineral oil Impregnated Pressboard Material

Classification of thermal ageing impact of ester fluid‐impregnated pressboard material adopting LIBS

Degradation Assessment of Ester Liquids

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