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Pressboard

About: Pressboard is a research topic. Over the lifetime, 1123 publications have been published within this topic receiving 9089 citations.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the breakdown and V-t characteristics of glass fiber reinforced plastics (GFRP) and pressboard in LN2 are discussed and compared with solid insulators.
Abstract: HTS transformer, without any loss of insulation lifetime due to the reduction in terms of size and weight, can increase the overload capacity, and have some benefits such as the improvement in efficiency, minimization of environmental pollution, and convenient spatial arrangement, which contribute a lot to electric power system operation. However, for practical insulation design of the HTS transformer, it is necessary to establish the research on electrical properties LN2 as well as solid insulators. These solid insulators have been used as main insulations for HTS transformer. In this paper, we discussed breakdown and V–t characteristics of glass fiber reinforced plastics (GFRP) and pressboard in LN2.

4 citations

Proceedings ArticleDOI
01 Oct 2013
TL;DR: In this paper, the surface charge distribution on oil impregnated pressboard produced by the needle plate electrode based on an electrostatic capacitive probe measuring system was studied and it was found that under the highly non-uniform DC electric field, surface charge polarity on oil-impregnated pressedboard mainly depend on the polarity of applied voltage and the accumulation and dissipation characteristics of the surface charges under the positive stress are different from that under negative stress.
Abstract: It is very important of the surface charge distributions on the oil impregnated pressboard under nonuniform DC electric field, for the design and application issue of a converter transformer, which is not reported in the literature. In order to have a better understanding of the characteristics of the surface charges on oil impregnated pressboard produced by the non-uniform DC electric field, we studied surface charge distribution on oil impregnated pressboard produced by the needle plate electrode based on an electrostatic capacitive probe measuring system. It is found that under the highly non-uniform electric field, the surface charge polarity on oil impregnated pressboard mainly depend on the polarity of applied voltage and the accumulation and dissipation characteristics of the surface charges under the positive stress are different from that under the negative stress.

4 citations

Dissertation
19 Jun 2012
TL;DR: In this paper, the authors investigate the creepage discharges along the surface of pressboard in esters and mineral oil under ac divergent electric field, and show that the presence of a solid surface can promote the development of discharges, especially those occurring in negative half cycles, and shifts more discharges towards the zero-crossing phase angles.
Abstract: Ester liquids including natural ester and synthetic ester are considered as potential substitutes for mineral oil, due to their good biodegradability and high fire points. Although these liquids have been widely used in distribution and traction transformers, research efforts are required for the purposes of design and manufacture of high voltage and large power transformers which are filled by esters. Indeed, it would be risky to apply esters in large power transformers without thorough understandings of their behaviours in large gaps and/or when combined with pressboard insulation. Therefore, investigations of creepage discharges along the surface of pressboard in esters are vitally important and their behaviours should be compared with those of mineral oils. This thesis is aimed to investigate the creepage discharges along pressboard in esters and mineral oil under ac divergent electric field. Apparent charges, current signals and images of streamer channels were obtained synchronously to identify whether and how the introduction of pressboard surface would influence the inception and propagation of discharges as compared to tests in open gap. When over-stressed by higher voltages, the surface tracking along the pressboard-ester interface, triggered by sustaining creepage discharges, was studied and the evolutions of accompanying creepage discharge patterns were investigated. In these experiments, both esters and mineral oil impregnated pressboards were comparatively studied. The test results indicated that at the inception stage, the presence of pressboard or any other solid types in different liquids under test do not influence the PD inception voltages; in the propagation stage, solid surface tends to promote the development of discharges, especially those occurring in negative half cycles, and shifts more discharges towards the zero-crossing phase angles. This discharge promotion effect is much more evident in esters than in mineral oil, probably because of higher discharge intensity in esters and higher viscosity of esters. The space charge effect and the residual low density channel effect are proved as the mechanisms best explaining the influences of solids on creepage discharges.Under higher voltages, it was found that the impregnated pressboard is susceptible to discharge erosion characterized by ?white and carbonized tree-shaped marks?, due to intense discharges occurring on or near the pressboard surface. The ?white mark? appears at a lower voltage and propagates more easily on ester impregnated pressboard. The gaseous ?white mark? channels will attract the subsequent discharges to follow the same discharge routes; the accumulative energy dissipation in these channels will then result in the carbonization of the channels. Once formed, the surface tree-shaped mark can continue to grow even under reduced voltage levels until it bridges the gap and causes the final flashover.

4 citations

Proceedings ArticleDOI
Hitoshi Okubo1, R. Shimizu, K. Kato, Naoki Hayakawa, Masayuki Hikita 
15 Jul 1996
TL;DR: In this paper, the authors measured the electric field in transformer oil/solid dielectrics composite insulation system under dc voltage application using Kerr electro-optic measurement system and found that electric field reached a magnitude of 2.7 times as much as the average dc applied field.
Abstract: We measured the electric field in transformer oil/solid dielectrics composite insulation system under dc voltage application using Kerr electro-optic measurement system. When a pressboard was inserted between two parallel-plane electrodes, the electric field at cathode side of pressboard decreased with time. On the other hand, the electric field at anode side increased initially with time, reached a maximum value and then fell down. Next, we measured the electric field after polarity reversal of dc voltage. The results revealed that the electric field reached a magnitude of 2.7 times as much as the average dc applied field. We interpreted the above results in terms of a charge dynamic model considering the difference in charge accumulation speed on pressboard between positive and negative charges.

4 citations

Proceedings ArticleDOI
09 Sep 2008
TL;DR: Aging of oil-paper insulation was investigated under controlled laboratory conditions in this article, where traditional and modern diagnostic tools and techniques were discussed, and the suitability of each method was analyzed along with its interpretation scheme.
Abstract: Aging of oil-paper insulation was investigated under controlled laboratory conditions. Traditional and modern diagnostic tools and techniques are discussed. Insulation condition testing includes common chemical diagnostics such as acidity tests and several new chemical techniques such as determination of relative content of dissolved decay products by spectrophotometry, solid suspension by turbidimetry, Fourier transform infrared spectroscopy, and electrical diagnostic techniques that have gained exceptional importance for utility professionals, such as polarisation/depolarisation current and frequency domain dielectric spectroscopy measurements. Based on the preliminary results, the suitability of each method analyzed along with its interpretation scheme. Finally, recommendations for further investigation are presented.

4 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202266
202140
202059
201966
201882