Geometry impact on streamer propagation in transformer insulation liquids

Liu, Rongsheng; Törnkvist, C.; Chandramouli, Vijaya; Girlanda, Orlando; Pettersson, Lars

doi:10.1109/ceidp.2010.5724093

Cited by 7 publications

(15 citation statements)

References 6 publications

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“…Performed test study can therefore be compared to a larger database. The following studies are compared to the two analyzed setups in this contribution: [3][4][5]8,28,29]. First comparisons are drawn on the different electrode arrangements selected.…”

Section: Comparison Of Different Setups and Explanation Of Their Breamentioning

confidence: 99%

“…Group (i) consists of the arrangements of studies [5,8,29] and the present study. Liu et al in [5] shows a comparable mean breakdown voltage for natural ester liquid and mineral oil at 25 mm oil gap under positive 1.2/50 µ s impulse for needle-sphere and needle-plate arrangements. For negative impulse voltages, mineral oil shows significantly larger breakdown voltages than the natural ester liquid.…”

Section: Needle Arrangement Group (I)mentioning

confidence: 99%

“…A comparison of breakdown voltages of the different studies is given in Figure 10. [5] for natural ester liquid and mineral oil.…”

Section: Needle Arrangement Group (I)mentioning

confidence: 99%

“…Group (ii) represents the arrangements of the studies [2][3][4][5] and the present study. A comparison between [2] and the present study has already been performed in Section 3.3.…”

Section: Conductor Arrangement Group (Ii)mentioning

confidence: 99%

“…The dielectric strength of insulating liquids is one of the main parameters relevant for power transformers. Several studies showed a comparable dielectric strength of the same used natural ester liquids compared to mineral oil under homogeneous and slightly inhomogeneous fields at lightning impulse (LI) [2][3][4] or with a different natural ester liquid [5].…”

Section: Introductionmentioning

confidence: 99%

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Lightning Impulse Withstand of Natural Ester Liquid

et al. 2018

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Due to the low biodegradability of mineral oil, intense research is conducted to define alternative liquids with comparable dielectric properties. Natural ester liquids are an alternative in focus; they are used increasingly as insulating liquid in distribution and power transformers. The main advantages of natural ester liquids compared to mineral oil are their good biodegradability and mainly high flash and fire points providing better fire safety. The dielectric strength of natural ester liquids is comparable to conventional mineral oil for homogeneous field arrangements. However, many studies showed a reduced dielectric strength for highly inhomogeneous field arrangements. This study investigates at which degree of inhomogeneity differences in breakdown voltage between the two insulating liquids occur. Investigations use lightning impulses with different electrode arrangements representing different field inhomogeneity factors and different gap distances. To ensure comparisons with existing transformer geometries, investigations are application-oriented using a transformer conductor model, which is compared to other studies. Results show significant differences in breakdown voltage from an inhomogeneity factor of 0.1 (highly inhomogeneous field) depending on the gap distance. Larger electrode gaps provide a larger inhomogeneity at which differences in breakdown voltages occur.

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Section: Comparison Of Different Setups and Explanation Of Their Breamentioning

confidence: 99%

Section: Needle Arrangement Group (I)mentioning

confidence: 99%

“…A comparison of breakdown voltages of the different studies is given in Figure 10. [5] for natural ester liquid and mineral oil.…”

Section: Needle Arrangement Group (I)mentioning

confidence: 99%

“…Group (ii) represents the arrangements of the studies [2][3][4][5] and the present study. A comparison between [2] and the present study has already been performed in Section 3.3.…”

Section: Conductor Arrangement Group (Ii)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lightning Impulse Withstand of Natural Ester Liquid

et al. 2018

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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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Flashover Feature along Oil/Pressboard Interfaces

Liu

Girlanda

2018

2018 IEEE 2nd International Conference on Dielectrics (ICD)

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Geometry impact on streamer propagation in transformer insulation liquids

Cited by 7 publications

References 6 publications

Lightning Impulse Withstand of Natural Ester Liquid

Lightning Impulse Withstand of Natural Ester Liquid

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

Flashover Feature along Oil/Pressboard Interfaces

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