Comprehensive Investigation on Service Aged Power Transformer Insulating Oil After Decades of Effective Performance in Field

Mehmood, Muhammad Ali; Nazir, M. Tariq; Li, Jian; Wang, Feipeng; Azam, Muhammad Muaaz

doi:10.1007/s13369-020-04559-7

Cited by 13 publications

(4 citation statements)

References 43 publications

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“…More investigations onto the chemical composition are needed to assess ageing by-product in mineral oil, especially after electrical stress. Several studies [15][16][17] have focused on the analysis of the behavior of the transformer insulating oil during aging by infrared spectroscopy, based on the fact that, the deterioration of the properties of insulating materials, over time is evidenced by changes in the chemical structure.…”

Section: Fds Analysis Of the Insulating Liquidsmentioning

confidence: 99%

FTIR and FDS assessment of mineral oil under low electrical discharge

Saliha¹,

Fadila²,

Issouf³

et al. 2022

Diagnostyka

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Transformers are crucial elements in the transmission and distribution of electrical energy. The importance of diagnosing these equipments are two-fold: (1) the necessity of service reliability and (2) the likelihood to avoid economic and environmental concerns. Under service conditions, the electrical and thermal stresses or chemical contaminants may degrade the insulation oil inside the transformer and cause incipient failures or reduce its service life. Partial discharges well recognized to be among the most common stresses that can lead to slow but steady degradation of insulating oil in transformers. The present work aims at understanding the influence of low energy electrical discharge on mineral oil based on two spectroscopic methods: FTIR spectroscopy and Frequency Domain Spectroscopy (FDS). An electrical fault has been created by continuous discharge of 10 kV on the surface of various oil samples according to the ASTM D6180. From the FDS results, it was found that the amount of charge carriers and moisture increased with the aging time elapsed that influences the conduction phenomena and in turn, increases the dissipation factor. These results are confirmed by the FTIR results, which show that the intensity of the peak absorbance of the C-H and C-C functional group decreased with aging. The application of these two methods may help monitoring the condition of oil. A combined FTIR and FDS measurements highlighted the correlations between modifications in electrical properties and changes in the chemical structure of the oil under electrical accelerated ageing.

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Section: Fds Analysis Of the Insulating Liquidsmentioning

confidence: 99%

FTIR and FDS assessment of mineral oil under low electrical discharge

Saliha¹,

Fadila²,

Issouf³

et al. 2022

Diagnostyka

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show abstract

“…Biodiesel is used as an alternative fuel to petrodiesel; the moisture content influences the extent of transesterification of diesel mixture and thus the fuel characteristics [6]. Insulating oil serves in insulation, arc suppression, and cooling in power systems [7][8][9]. The accurate detection of microwater is critical to the safe operation of substation equipment [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Modification of the Maxwell–Wagner Heterogeneous Dielectric Model for Heterogeneous Polymers and Emulsions

Qian

Yan

et al. 2022

Polymers

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In heterogeneous polymers and emulsions, the volume fraction of the discrete phase and the frequency of electromagnetic waves affect the accuracy of the dielectric model. The integral method was used to modify the Maxwell–Wagner (M–W) heterogeneous dielectric theory, and a new model for the complex dielectric constant of polymers and emulsions was established. The experimental data were compared with the results of the M–W heterogeneous dielectric integral modification model and other theoretical models for different frequencies and volume fractions of the discrete phase. We discovered that with a decreasing volume fraction of the discrete phase, the dominant frequency range of the integral modification model expanded. When the volume fraction of the discrete phase is 10%, the dominant frequency range reaches 3 GHz. When the volume fraction of the discrete phase is 1%, the dominant frequency range reaches 4 GHz. When the volume fraction of the discrete phase is 0.06%, the dominant frequency range of the real part reaches 9.6 GHz, and the dominant frequency range of the imaginary part reaches 7.2 GHz. These results verify the advantages of the M–W modification model, which provides a theoretical basis to study the dielectric properties of polymers and emulsions, as well as for microwave measurement.

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“…The oil-impregnated paper, as the main insulation of the power transformer, plays an important role in the safe operation of electrical equipment. During the operation of the transformer, the insulation paper is prone to generating space charge due to the influence of thermal stress and other factors, which will cause local electric field distortion, aging, and breakdown of the insulation system, and poses a great threat to the safe and reliable operation of equipment [ 1 , 2 , 3 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Aging Characteristics of Transformer Oil-Impregnated Insulation Paper Based on Trap Parameters

Wei

Wang

et al. 2021

Polymers

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Oil-impregnated insulation paper is an important part of transformers; its performance seriously affects the life of power equipment. It is of significance to study the aging characteristics and mechanism of oil-impregnated insulation paper under thermal stress for transformer status detection and evaluation. In the work, the accelerated thermal aging was carried out at 120 °C, and DP1490, DP787, and DP311 samples were selected to represent the new, mid-aging, and late-aging status of the transformer, respectively. The space charge distribution within the specimens was measured by the pulsed electro-acoustic (PEA) method and the trap parameters were extracted based on the measurement curves. Further, the aging mechanism was studied by molecular simulation technology. A typical molecular chain defect model was constructed to study the motion of cellulose molecules under thermal stress. The experimental results show that the corresponding trap energy levels are 0.54 eV, 0.73 eV, and 0.92 eV for the new specimen, the mid-aging specimen, and the late aging specimen, respectively. The simulation results show that the trapped energy at the beginning of aging is mainly determined by the loss of H atoms. The changes in trap energy in the middle stage of aging are mainly caused by the absence of some C atoms, and the trap energy level at the end of aging is mainly caused by the breakage of chemical bonds. This study is of great significance to reveal the aging mechanism of oil-impregnated insulation paper and the modification of insulation paper.

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Comprehensive Investigation on Service Aged Power Transformer Insulating Oil After Decades of Effective Performance in Field

Cited by 13 publications

References 43 publications

FTIR and FDS assessment of mineral oil under low electrical discharge

FTIR and FDS assessment of mineral oil under low electrical discharge

Modification of the Maxwell–Wagner Heterogeneous Dielectric Model for Heterogeneous Polymers and Emulsions

Aging Characteristics of Transformer Oil-Impregnated Insulation Paper Based on Trap Parameters

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