Characteristics of Negative Streamer Development in Ester Liquids and Mineral Oil in a Point-To-Sphere Electrode System with a Pressboard Barrier

Rózga, Paweł; Stanek, Marcin; Pasternak, Bartlomiej

doi:10.3390/en11051088

Cited by 24 publications

(12 citation statements)

References 20 publications

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“…However, lately they have been used more and more often in power transformers [7,8]. This can be affected by synthetic esters properties, such as breakdown voltage, electric permittivity, biodegradability, and flash point [9].…”

Section: Introductionmentioning

confidence: 99%

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Nadolny

Dombek

2018

Energies

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The article discusses thermal properties of synthetic ester admixed with nanoparticles. The analyzed thermal properties were: thermal conductivity λ, kinematic viscosity υ, density ρ, specific heat cp, and the thermal expansion factor β- all obtained by means of measurements. On the basis of these, the authors calculated the heat transfer factor α, which determines the ability of the liquid to heat transport. The authors used nanoparticles of fullerene C60 and titanium oxide TiO2. The analysis of the thermal properties was done for the temperatures of 25, 40, 60 and 80 °C. The authors analyzed the impact of nanoparticles C60 and TiO2 on thermal properties of synthetic ester. They proved that fullerene C60 in principle had no influence on heat transfer factor α of the ester, while titanium oxide TiO2 had some positive influence on the factor, the value of which increased about 1–3%.

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Section: Introductionmentioning

confidence: 99%

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Nadolny

Dombek

2018

Energies

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“…The 50% lightning breakdown voltage of the MO impregnated pressboard is almost the same as the open oil gap shown in Figure 9. It is well reported that the introduction of the pressboard does not decrease the 50% lightning breakdown voltages of oil impregnated pressboard [14], [16], [25], [26]. In oil impregnated pressboard, both materials have components with different dielectric constants where oil has a lower dielectric constant and dielectric strength compared to the pressboard [27].…”

Section: Discussionmentioning

confidence: 99%

Pre-Breakdown Streamer Propagation and Positive Lightning Breakdown Characteristics of Palm Oil Impregnated Aged Pressboard

et al. 2020

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This paper presents the investigation on the breakdown characteristics and pre-breakdown streamer propagation of Palm Oil (PO) impregnated aged pressboard under positive lightning impulse voltages. The experimental work was carried out under a non-uniform field with needle-plane electrodes configuration. The streamer stopping length and breakdown voltage of 2 types of refined, bleached, and deodorized palm oil were examined in the presence of new and aged pressboards. The pressboard was placed in parallel to the needle-plane electrode at a gap distance of 50 mm. The lightning breakdown voltage was applied to the samples based on 1 shot per step rising voltage method under positive polarity as per IEC 60897. The presence of impregnated pressboard in both PO slightly increases the 50% positive lightning breakdown voltages. PO impregnated pressboards have lower 50% positive lightning breakdown voltages than MO. After subjected to ageing, the positive lightning breakdown voltages for PO and MO impregnated pressboards decrease. In the presence of aged pressboard, the streamers in PO generally propagate further than MO at the same voltage level. INDEX TERMS Lightning impulse breakdown voltage, non-uniform field, palm oil, aged pressboard, streamer characteristics, transformers.

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“…An electrode system (Figure 18a), in which the creeping discharges were generated on a pressboard sample with a diameter of 100 mm and a height of 3 mm, was placed in the oil-filled transformer tank (Figure 18b). These types of discharges were selected due to the fact that together with turn-to-turn discharges, they are the most dangerous defects that typically result in catastrophic failures at normal operating conditions [41][42][43][44][45]. An electrode system (Figure 18a), in which the creeping discharges were generated on a pressboard sample with a diameter of 100 mm and a height of 3 mm, was placed in the oil-filled transformer tank (Figure 18b).…”

Section: Sensitivity Of Detection Of Ae Waves Generated By Pdmentioning

confidence: 99%

Active Dielectric Window: A New Concept of Combined Acoustic Emission and Electromagnetic Partial Discharge Detector for Power Transformers

Sikorski

2018

Energies

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The detection and location of partial discharge (PD) is of great significance in evaluating the insulation condition of power transformers. This paper presents an active dielectric window (ADW), which is a new concept of combined acoustic emission (AE) and electromagnetic PD detector intended for assembly in a transformer’s inspection hatch. The novelty of this design lies in the fact that all structural components of an ultrasonic transducer, i.e., the matching and backing layer, an active piezoelectric element with electrodes, and electrical leads, were built into a dielectric window. Due to the fact that its construction was optimized for work in mineral oil, it is characterized by much higher sensitivity of PD detection than a general-purpose AE sensor mounted outside a transformer tank. Laboratory tests showed that the amplitude of the AE pulses generated by creeping discharges, which were registered by the ADW, was around five times higher on average than the pulses registered by a commonly used contact transducer. A possibility of simultaneous detection of acoustic and electromagnetic pulses (with an integrated ultra-high frequency (UHF) antenna) is an important advantage of the ADW. It allows for an increase in the reliability of PD detection, the accuracy of defect location, and the effectiveness of disturbance identification. This paper describes in detail the applied methods of designing and modeling the ADW components, the manufacturing process of the prototype construction, and the results of preliminary laboratory tests, in which the detector’s sensitivity as well as the efficiency of the PD source location were evaluated.

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Characteristics of Negative Streamer Development in Ester Liquids and Mineral Oil in a Point-To-Sphere Electrode System with a Pressboard Barrier

Cited by 24 publications

References 20 publications

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Pre-Breakdown Streamer Propagation and Positive Lightning Breakdown Characteristics of Palm Oil Impregnated Aged Pressboard

Active Dielectric Window: A New Concept of Combined Acoustic Emission and Electromagnetic Partial Discharge Detector for Power Transformers

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