Fire safety and electrical properties of mixtures of synthetic ester/mineral oil and synthetic ester/natural ester

Dombek, Grzegorz; Gielniak, J.

doi:10.1109/tdei.2018.007223

Cited by 50 publications

(31 citation statements)

References 25 publications

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“…The superior fire performance of ester-based oils has been verified for different mixtures of mineral oil, synthetic esters and natural esters [62]. Their dielectric properties, calorific values, fire point, and flash point have been reported as a function of different mixture ratios [125]. esters.…”

Section: F Environmental and Fire Propertiesmentioning

confidence: 90%

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

et al. 2019

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Ester-based dielectric fluids have gained widespread popularity for applications in high voltage apparatus. Synthetic and natural esters have been subjected to research for decades vis-à-vis mineral insulating oils around the world. Although many researchers favor the application of ester fluids, utilities are still uncertain and application of these alternatives remains a challenge. The intent of this survey is to present recent research progress and highlight the state of the art of key aspects that should be emphasized in future research. The contemporary research scenarios pertaining to the performance of ester fluids versus mineral oils, miscibility, and retrofilling of insulating fluids are discussed. In addition, pre-breakdown phenomena, usage of esters in on-load tap changers, environmental and fire resistance properties, and use of esters in cold climates are also discussed. Importantly, challenges and future aspects that should be investigated to improve the existing knowledge of ester dielectric fluids for applications in transformer technology are highlighted.

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Section: F Environmental and Fire Propertiesmentioning

confidence: 90%

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

et al. 2019

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“…In 2018, Beroual et al [12] found both natural ester and synthetic ester mixed with mineral oil can increase the DC and AC breakdown voltages of mineral oil, and natural ester mixed oil has a larger increase extent. Dombek and Gielniak [13] studied the flash point and ignition point of synthetic ester–mineral oil mixed oil and found that flash point and ignition point of the mixed oil gradually increase with the addition of synthetic esters proportion. Beldjilali et al [14] focused on the isothermal discharge current of mixed insulation oil and proposed a mixed insulation oil with 15% olive oil and 85% mineral oil, which has a low steady‐state current, minimum conductivity, and electron mobility.…”

Section: Introductionmentioning

confidence: 99%

Comparison of AC breakdown characteristics on insulation paper (pressboard) immersed by three‐element mixed insulation oil and mineral oil

et al. 2020

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Insulation oil is an important dielectric in power devices, and many studies on mixed insulation oil have been conducted in recent years to improve the performance of insulation oils. To replace mineral oil directly, the authors previously developed a novel three-element mixed insulation oil successfully; the main parameters of which satisfy the IEC 60296-2012 standard for mineral oil. In the present study, the AC breakdown properties of insulation paper (pressboard) immersed by the new mixed oil and naphthenic mineral oil were compared. For both insulation oils, the increase in temperature cannot significantly reduce the breakdown strength of oil-immersed insulation paper (pressboard) at a low moisture content, and the increment of moisture content cannot reduce the breakdown voltage at a low temperature (25°C). The breakdown voltage decreases only when the two factors increase simultaneously. For the mixed and mineral oils, the AC breakdown voltage of oilimmersed paper (pressboard) with different thicknesses has significant difference. The mineral oil has a high breakdown voltage for the thin insulation paper, whereas the mixed oil has a high breakdown voltage when the thickness of the insulation paper (pressboard) exceeds 0.2 mm. This phenomenon is mainly caused by the breakdown field strength that varies with the increase of dielectric thickness and the different change trends of paper (pressboard) immersed with the mixed and the mineral oils. Moreover, the stack of thin multilayer insulation paper enables the mixed oil-immersed paper to have a higher breakdown strength than the mineral oil-immersed paper. For the AC breakdown voltage of oil-immersed pressboard with an oil-gap structure, the mixed oil is comprehensively superior to the mineral oil due to its larger relative permittivity.

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“…The asset management strategy developed by most power distribution companies, which is directed towards an extension of transformer life, results mostly from the high cost of the device purchased as well as long delivery time, reaching over a year. However, such policy increases the probability of catastrophic failure occurrence, which is followed by a number of negative consequences, such as a threat to the life of the substation staff, significant economic losses, environmental hazards (oil leaks or fire), and local blackouts [1,2,3,4,5]. Therefore, recently, an increase of requirements towards the reliability of the exploited power transformers and the demand for professional services and diagnostics solutions has been observed.…”

Section: Introductionmentioning

confidence: 99%

Development of Acoustic Emission Sensor Optimized for Partial Discharge Monitoring in Power Transformers

Sikorski

2019

Sensors

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The acoustic emission (AE) technique is one of the unconventional methods of partial discharges (PD) detection. It plays a particularly important role in oil-filled power transformers diagnostics because it enables the detection and online monitoring of PDs as well as localization of their sources. The performance of this technique highly depends on measurement system configuration but mostly on the type of applied AE sensor. The paper presents, in detail, the design and manufacturing stages of an ultrasensitive AE sensor optimized for partial discharge detection in power transformers. The design assumptions were formulated based on extensive laboratory research, which allowed for the identification of dominant acoustic frequencies emitted by partial discharges in oil–paper insulation. The Krimholtz–Leedom–Matthaei (KLM) model was used to iteratively find optimal material and geometric properties of the main structures of the prototype AE sensor. It has two sensing elements with opposite polarization direction and different heights. The fully differential design allowed to obtain the desired properties of the transducer, i.e., a two-resonant (68 kHz and 90 kHz) and wide (30‒100 kHz) frequency response curve, high peak sensitivity (−61.1 dB ref. V/µbar), and low noise. The laboratory tests confirmed that the prototype transducer is characterized by ultrahigh sensitivity of partial discharge detection. Compared to commonly used commercial AE sensors, the average amplitude of PD pulses registered with the prototype sensor was a minimum of 5.2 dB higher, and a maximum of 19.8 dB higher.

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Fire safety and electrical properties of mixtures of synthetic ester/mineral oil and synthetic ester/natural ester

Cited by 50 publications

References 25 publications

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

Comparison of AC breakdown characteristics on insulation paper (pressboard) immersed by three‐element mixed insulation oil and mineral oil

Development of Acoustic Emission Sensor Optimized for Partial Discharge Monitoring in Power Transformers

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