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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.


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Proceedings ArticleDOI
15 Jul 1996
TL;DR: In this paper, the authors studied the inception and propagation of streamers in a pointplane gap, with and without pressboard interfaces parallel to the field, and found that the negative streamers have about twice as high a breakdown voltage as the positive ones.
Abstract: Inception and propagation of streamers in a point-plane gap, with and without pressboard interfaces parallel to the field, have been studied. Current and light-emission have been recorded. Positive streamers propagate at about 2-4000 m/s at voltages up to two times the minimum breakdown voltage. Above this voltage a fast event (>100 km/s) may occur, preceded by streamers propagating with velocities in the 10-20 km/s range. The negative streamers have about twice as high a breakdown voltage as the positive ones. Also negative streamers may develop into a fast event. Solid field parallel pressboard does not change the breakdown voltage, but makes inception of fast events easier. The breakdown process in oil shows several similarities to a gas breakdown.

11 citations

Proceedings ArticleDOI
03 Jul 1994
TL;DR: In this article, a method of calculating the complex permittivity of pressboard involves interdigitated electrodes, applied only to one surface of the sample, making it possible to measure spatial distributions of the dielectric properties.
Abstract: The dielectric spectrum of pressboard, (i.e. its complex permittivity as a function of frequency), is related to its moisture content and to its temperature. Consequently, it is possible to use dielectrometry measurements to measure a pressboard sample's moisture content. A method of calculating the complex permittivity of pressboard involves interdigitated electrodes, applied only to one surface of the sample. Since the electric field's depth of penetration is dependent on the spatial wavelength of the electrodes, different sensors yield information from different depths in the material, making it possible to measure spatial distributions of the dielectric properties. This can allow the study of the diffusion of water in pressboard. >

10 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of thermal aging of cellulose pressboard using terahertz time-domain spectroscopy were examined. But the results indicated that the tera-hertz techniques could be very useful, especially in the electric power industry, which requires a variety of methods for internal non-destructive testing to ensure the safety and reliability of insulation materials in electric power facilities and components.

10 citations

Journal ArticleDOI
TL;DR: In this article , the aging marker for palm fatty acid ester (PFAE)-filled transformer was investigated and the results demonstrate that 2ACF and 5MEF can also be used as aging markers for transformer in spite of their much lower concentrations in the aged fluids.
Abstract: The investigation on the aging marker for palm fatty acid ester (PFAE)-filled transformer was performed. Sealed aging stainless steel tanks containing transformer components in the same ratio as a 27-MVA power transformer, were aged at 151 °C–168.5 °C for 48–2880 h in a strictly controlled oxygen-free and low initial moisture environment. The generation of 2-furaldehyde (2FAL) and other four kinds of furans including 5-hydroxymethylfurfural (5HMF), 2-furfuryl alcohol (2FOL), 2-acetylfuran (2ACF), and 5-methyl furfural (5MEF) from cellulosic insulating components impregnated in mineral oil (MO) and PFAE after thermally aging tests are determined and compared. The results indicate that the concentration of 2FAL, 2ACF, and 5MEF maintains an increasing trend with the aging time and temperature for both fluids. The correlations between 2FAL and the degree of polymerization (DP) of high-density pressboard (HPB) in both fluids are established. The results demonstrate that 2ACF and 5MEF can also be used as aging markers for transformer in spite of their much lower concentrations in the aged fluids.

10 citations

Journal ArticleDOI
22 May 2018-Energies
TL;DR: In this article, a typical plate electrode structure was employed in the laboratory to conduct a breakdown test on the oil-pressboard insulation, where the electrical field distribution and the DC contents of the transformer oil and the pressboard in composite insulation were simulated by their dielectric parameters.
Abstract: An AC-DC combined voltage is applied to the oil-pressboard insulation near the valve side during the operation of a converter transformer. To study the breakdown characteristics of an oil-pressboard insulation under such voltages, a typical plate electrode structure was employed in the laboratory to conduct a breakdown test on the oil-pressboard insulation. The electrical field distribution and the DC contents of the transformer oil and the pressboard in composite insulation under the AC-DC combined voltage were simulated by their dielectric parameters. The breakdown strength of the transformer oil decreases with the increase in the DC content of the applied voltage, whereas that of the pressboard increases. For the oil-pressboard insulation, the breakdown voltage increases first and then decreases. The electric field strength decreases in the transformer oil with the increase in the DC content, whereas it increases in the pressboard. And the DC contents of the transformer and the pressboard in composite insulation were different from that of the applied voltage. Finally, based on the above results, a mathematical model was proposed to describe the breakdown characteristics of the oil-pressboard insulation under the AC-DC combined voltage; the theoretical and experimental results were in good agreement.

10 citations


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