Comparative study on inhomogeneous field breakdown in natural ester liquid and mineral oil

Haegele, S.; Tenbohlen, Stefan; Rapp, Kevin; Sbravati, Alan

doi:10.1109/ceidp.2016.7785488

Cited by 10 publications

(7 citation statements)

References 7 publications

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“…Even though RBO almost has a larger breakdown voltage than PO, the 50% breakdown voltage of RBO is quite close with PO at all gap distances. These findings are due to the physical and chemical properties of the RBO, and PO are almost similar according to [13,14,23].…”

Section: Effect Of Small Gap Distancesmentioning

confidence: 63%

“…Lightning studies can be carried out under uniform or quasi-uniform, and non-uniform electrical fields [12,14,27,28]. The insulations between turns, disks and windings of the transformer are in a quasi-uniform electric field, which is experienced by most insulation materials inside a transformer.…”

Section: Preparation Of Samplementioning

confidence: 99%

“…Before vegetable oils can be accepted as an alternative to MO, they must be safe, economical and offer a high standard of electrical properties over the transformer lifespan. Recently, extensive works were carried out to investigate the suitability of vegetable oils as the alternative to MO [12][13][14][15][16][17][18]. The studies evaluated dielectric properties, physical and chemical performances under different conditions and ageing properties.…”

Section: Introductionmentioning

confidence: 99%

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Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

et al. 2021

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Transformer oil does not only serve as an insulating liquid, but also in removing heat from the windings and cores. Mineral oil (MO) has been widely used in transformers for more than 150 years. Recently, researchers have attempted to search for alternative insulating oils due to the possibility that MO will run out in the future together with the concern on fire safety and environmental pollution. Among the potential oils is rice bran oil (RBO). This work presents the studies of the lightning impulse (LI) of RBO behavior under various electric fields, gap distances and testing methods. The electrical performances of LI tests show that RBO and Palm Oil (PO) have lower LI breakdown voltage than MO under both uniform and non-uniform electric fields. However, the difference in LI breakdown voltages between RBO, PO and MO are slightly small which is less than 20%. In addition, there is no significant effect in the various testing methods under both uniform field and non-uniform field where the percentages of difference are less than 12% and 8% respectively. The data of LI breakdown voltage were statistically analysed to predict the withstand voltage and 50% breakdown voltage of oil samples by using Weibull distribution. The Weibull distribution of MO, PO and RBO has well fit with the fitting line. Finally, the relationship between LI voltages under a non-uniform field with various parameters of PO and RBO was obtained and proposed. From this work, it can be concluded that RBO shows promising results to be considered as an alternative to MO in transformer applications.

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Section: Effect Of Small Gap Distancesmentioning

confidence: 63%

Section: Preparation Of Samplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

et al. 2021

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“…Based on the above phenomena, the effect of field uniformity is a topic of interest to investigate the discharge and breakdown phenomena in ELs. Some studies have focused on the effects of field uniformity regarding to the breakdown mechanism transition phenomenon from streamer initiation controlled breakdown to streamer propagation controlled breakdown [13,14,22], and studied on the LIBDV difference between ELs and MOs [20,25,26]. Nevertheless, the understanding on the transition field factor boundaries among different experimental phenomena is still not clear enough.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis and interpretation on lightning impulse breakdown voltages of ester liquids under varying field uniformity

Yu,

Liu,

Wang

2023

High Voltage

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Ester liquids (ELs), as the alternative transformer liquids to the conventional mineral oils (MOs), have been increasingly used in power transformers with high voltage ratings. Among various properties, the lightning impulse breakdown voltages (LIBDVs) have been studied elaborately in the past 2 decades under different electric field uniformities. The electric field uniformities do have an effect on the breakdown characteristics, for example, breakdown mechanisms, polarity effects, and differences of LIBDV between ELs and MOs, which is quantitatively investigated based on the LIBDVs collected from the literatures. The breakdown mechanism transition phenomenon between streamer initiation dominated breakdown and streamer propagation dominated breakdown has been reviewed firstly. Then, the transition field factor boundaries to observe the polarity effect on LIBDVs are taken at around 20 for ELs and 10 for MOs. Besides, the transition field factor boundaries to observe the LIBDV distinctions between ELs and MOs are about 109 and 14 under positive and negative lightning impulse, respectively. The systematic analysis and interpretation on the transition field factor boundaries among different phenomena can provide insights on insulation design of ELs filled power transformers.

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“…In laboratory-based experimental work, to achieve a suitable non-uniform electric field distribution (with a η less than 0.1) for streamer propagation velocity studies, point-plane electrode geometries are used [34]. The precise value of η depends on the specific electrode and gap dimensions.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress

et al. 2022

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Liquid insulation is used in high voltage equipment such as power transformers as both dielectric medium and coolant. Breakdown in liquid insulation tends to be governed either by streamer initiation under more uniform fields, or by streamer propagation under more non-uniform fields. A model streamer propagation study, which screens the effectiveness of additives based on cyclohexane and mixtures with diethylaniline (DEA) and toluene, is presented in this paper. The effect of additives, at different concentrations, on streamer propagation velocity in cyclohexane under an applied lightning impulse voltage of positive polarity is studied. Cyclohexane (ionisation potential 9.88 eV) was chosen because, being a hydrocarbon, it shares similarities with the constituents of common insulating liquids. Previous studies have also shown how, in general, the addition of additives of lower ionization potential than the bulk liquid can slow down streamer propagation in insulating liquids. A point-plane electrode configuration of 70 mm gap with a 5 μm tip radius is used and subjected to an applied positive polarity impulse of 1.2/50 μs. A high velocity imaging system is also used to capture streamer images to validate a Time-To-Breakdown (TTB) measurement approach used in inferring approximate streamer velocity. The DEA (ionisation potential 6.98 eV) was found to be an effective additive to slow down positive polarity streamers in cyclohexane in the applied voltage range (≈220–280 kV peak) in concentrations above approximately 0.33% (by volume). Toluene (ionisation potential 8.82 eV) was found not to significantly slow down streamers in cyclohexane, even at 10% concentration, for the same voltage range. This is postulated to be due to the fact that toluene does not have a low enough ionisation potential (with respect to that of the cyclohexane) to change the streamer branching characteristics sufficiently during propagation.

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Comparative study on inhomogeneous field breakdown in natural ester liquid and mineral oil

Cited by 10 publications

References 7 publications

Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

Statistical analysis and interpretation on lightning impulse breakdown voltages of ester liquids under varying field uniformity

The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress

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