Weibull Statistics in Dielectric Strength of Oil-impregnated Pressboard under Ramped AC and DC Voltages

Nedjar, Mohammed

doi:10.17265/1934-8975/2013.12.021

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…A conductive path is formed in the process, which has been observed to degrade the insulation system. It has been reported that the resistance of oil-impregnated pressboards to DC voltage is superior to that of AC voltage, according to a reliability analysis based on step voltage practices [ 9 ]. The modelling of lightning strikes in transformers was undertaken by Florkowski and et al They discovered that the strength of the windings is influenced by the waveform of the applied voltage and the standard voltage pulse used.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Novel Solid Dielectric Material for Transformer Windings

Ersoy,

Atalar,

Aydoğan

2023

Polymers

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Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many researchers. It is worth noting that the electrical breakdown traits of insulation material are determined by their electrochemical and mechanical performance. Possible good mechanical, electrical, and chemical properties of new materials are considered during the generation process. Thermoplastic polyurethane (TPU) is often used as a high-voltage insulator due to its favorable mechanical properties, high insulation resistance, lightweight qualities, recovery, large actuation strain, and cost-effectiveness. The elastomer structure of thermoplastic polyurethane (TPU) enables its application in a broad range of high-voltage (HV) insulation systems. This study aims to evaluate the feasibility of using TPU on transformer windings as a solid insulator instead of pressboards. The investigation conducted through experiments sheds light on the potential of TPU in expanding the range of insulating materials for HV transformers. Transformers play a crucial role in HV systems, hence the selection of suitable materials like cellulose and polyurethane is of utmost importance. This study involved the preparation of an experimental setup in the laboratory. Breakdown tests were conducted by generating a non-uniform electric field using a needle–plane electrode configuration in a test chamber filled with mineral oil. Various voltages ranging from 14.4 kV to 25.2 kV were applied to induce electric field stress with a step rise of 3.6 kV. The partial discharges and peak numbers were measured based on the predetermined threshold values. The study investigated and compared the behaviors of two solid insulating materials under differing non-electric field stress conditions. Harmonic component analysis was utilized to observe the differences between the two materials. Notably, at 21.6 kV and 25.2 kV, polyurethane demonstrated superior performance compared to pressboard with regards to the threshold value of leakage current.

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Section: Introductionmentioning

confidence: 99%

Investigation of Novel Solid Dielectric Material for Transformer Windings

Ersoy,

Atalar,

Aydoğan

2023

Polymers

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Study of dielectric breakdown in liquid xenon with XeBrA: The xenon breakdown apparatus

Watson

Olcina

Soria

et al. 2023

Review of Scientific Instruments

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Maintaining the electric fields necessary for the current generation of noble liquid time projection chambers (TPCs), with drift lengths exceeding 1 m, requires a large negative voltage applied to their cathode. Delivering such high voltage is associated with an elevated risk of electrostatic discharge and electroluminescence, which would be detrimental to the performance of the experiment. The Xenon Breakdown Apparatus (XeBrA) is a 5-l, high voltage test chamber built to investigate the contributing factors to electrical breakdown in noble liquids. In this work, we present the main findings after conducting scans over stressed electrode areas, surface finish, pressure, and high voltage ramp speed in the medium of liquid xenon. Area scaling and surface finish were observed to be the dominant factors affecting breakdown, whereas no significant changes were observed with varying pressure or ramp speed. A general rise in both the anode current and photon rate was observed in the last 30 s, leading up to a breakdown, with a marked increase in the last couple of seconds. In addition, the position of breakdowns was reconstructed with a system of high-speed cameras and a moderate correlation with the Fowler–Nordheim field emission model was found. Tentative evidence for bubble nucleation being the originating mechanism of breakdown in the liquid was also observed. We deem the results presented in this work to be of particular interest for the design of future, large TPCs, and practical recommendations are provided.

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Weibull Statistics in Dielectric Strength of Oil-impregnated Pressboard under Ramped AC and DC Voltages

Cited by 2 publications

References 23 publications

Investigation of Novel Solid Dielectric Material for Transformer Windings

Investigation of Novel Solid Dielectric Material for Transformer Windings

Study of dielectric breakdown in liquid xenon with XeBrA: The xenon breakdown apparatus

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