Impact of thermal aging of transformer oil on UV-Vis optical spectrum and dielectric properties

Alshehawy, Abdelrahman M.; Mansour, Diaa‐Eldin A.; Rezk, A. M. Hassan; Ghali, Mohsen

doi:10.1109/mepcon.2016.7836996

Cited by 22 publications

(9 citation statements)

References 13 publications

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“…The oil samples were measured for their output power at 405 and 450 nm with a 1-mm pathlength cuvette. The estimated CI was calculated using Equations ( 1) and (2). The difference between the actual CI obtained from the ASTM D1500 measurement and the estimated CI using the developed model was then calculated and analyzed.…”

Section: Resultsmentioning

confidence: 99%

“…Power transformers are key assets of power utilities that ensure the regulation and distribution of electricity to housing and industrial areas. The insulation system is constantly exposed to electrical stress, mechanical stress, and thermal stress [1][2][3][4] during its operation. Lack of supervision of the condition of the transformer may cause catastrophic failures.…”

Section: Introductionmentioning

confidence: 99%

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Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser

Hadi

Ker

Lee

et al. 2021

Sensors

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The color of transformer oil can be one of the first indicators determining the quality of the transformer oil and the condition of the power transformer. The current method of determining the color index (CI) of transformer oil utilizes a color comparator based on the American Society for Testing and Materials (ASTM) D1500 standard, which requires a human observer, leading to human error and a limited number of samples tested per day. This paper reports on the utilization of ultra violet-blue laser at 405- and 450-nm wavelengths to measure the CI of transformer oil. In total, 20 transformer oil samples with CI ranging from 0.5 to 7.5 were measured at optical pathlengths of 10 and 1 mm. A linear regression model was developed to determine the color index of the transformer oil. The equation was validated and verified by measuring the output power of a new batch of transformer oil samples. Data obtained from the measurements were able to quantify the CI accurately with root-mean-square errors (RMSEs) of 0.2229 for 405 nm and 0.4129 for 450 nm. This approach shows the commercialization potential of a low-cost portable device that can be used on-site for the monitoring of power transformers.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser

Hadi

Ker

Lee

et al. 2021

Sensors

View full text Add to dashboard Cite

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“…The resulting mixture is then placed in an oven at 120 °C for different ageing times. The heat inside the oven increases the ageing rate, as shown in Equations (3), (4) and (5) [24] [25]. If the temperature increases to 7 °C, then the rate of degradation is doubled.…”

Section: B Experimental Setup and Preparation Of Transformer Oil Samplementioning

confidence: 99%

Transformer Oil Ageing Detection using Mach–Zender Interferometry Configuration as a Sensor

2019

IJRTE

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Abstract: Paper In this paper, the fabrication and characterisation of an optical fibre sensor for transformer oil ageing detection are presented. Bare fibre is used in the Mach-Zender interferometry (MZI) configuration as a sensing arm. Hydrofluoric acid (30%) and a power meter are used in sensor fabrication. The MZI sensor is affected by the changes of the refractive index (RI) of the transformer oil. The sensor operates according to different output power levels at the receiving end of the optical sensor. Results agree with the AC breakdown voltage test and oil absorption spectrum test. This work contributes to the improvement of transformer oil monitoring systems by ensuring the availability of oil information and protecting such systems from damage.

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“…Ultraviolet-visible (UV-Vis) is nowadays considered for the condition assessment of transformer oil. UV-Vis spectroscopy has exhibited a correlation with some chemical and physical properties [22,23] in addition to some dielectric properties of transformer oil [24]. Fourier transform infrared (FTIR) spectroscopy is another optical absorption spectroscopy technique that has shown a correlation between some absorption bands and aging byproducts produced due to the aging process of transformer oil [25,26].…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence Spectroscopy Measurements for Effective Condition Assessment of Transformer Insulating Oil

et al. 2021

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Condition assessment of insulating oil is crucial for the reliable long-term operation of power equipment, especially power transformers. Under thermal aging, critical degradation in oil properties, including chemical, physical, and dielectric properties, occurs due to the generation of aging byproducts. Ultraviolet-visible (UV-Vis) spectroscopy was recently proposed for the condition assessment of mineral oil. However, this absorption technique may involve all electronic states of the investigated material which typically yield a broad spectrum, and thus cannot precisely reflect the electronic structure of aged oil samples. It also cannot be implemented as an online sensor of oil degradation. In this paper, photoluminescence (PL) spectroscopy is introduced, for the first time, for effective condition assessment of insulating oil. The PL technique involves emission processes that only occur between a narrow band of electronic states that are occupied by thermalized electrons and consequently yields a spectrum that is much narrower than that of the absorption spectrum. Aged oil samples with different aging extents were prepared in the laboratory using accelerated aging tests at 120 °C, under which 1 day of laboratory aging is equivalent to approximately 1 year of aging in the field. These aged samples were then tested using PL spectroscopy with a wavelength ranging from 150 nm to 1500 nm. Two main parameters were evaluated for quantitative analysis of PL spectra: The full width at half-maximum and the enclosed area under the PL spectra. These parameters were correlated to the aging extent. In conjunction with PL spectroscopy, the aged oil samples were tested for the dielectric dissipation factor as an indication of the number of aging byproducts. Interestingly, we find a correlation between the PL spectra and the dielectric dissipation factor. The results of PL spectroscopy were compared to those of UV-Vis spectroscopy for the same samples and the parameters extracted from PL spectra were compared to the aging b-products extracted from UV-Vis spectra. Finally, the corresponding physical mechanisms were discussed considering the obtained results and the spectral shift for each spectrum. It was proved that PL spectroscopy is a promising technique for the condition assessment of insulating oil when compared to conventional transformer oil assessment measuring techniques and even to other optical absorption techniques.

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Impact of thermal aging of transformer oil on UV-Vis optical spectrum and dielectric properties

Cited by 22 publications

References 13 publications

Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser

Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser

Transformer Oil Ageing Detection using Mach–Zender Interferometry Configuration as a Sensor

Photoluminescence Spectroscopy Measurements for Effective Condition Assessment of Transformer Insulating Oil

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