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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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Journal ArticleDOI
TL;DR: In this paper, a method of drying cellulose insulation of distribution transformers with the use of synthetic ester is proposed, which uses the high solubility of water in the ester compared to other dielectric liquids.
Abstract: The article concerns a method of drying cellulose insulation of distribution transformers with the use of synthetic ester. This method uses the high solubility of water in the ester compared to other dielectric liquids. The method is based on the striving of the oil-paper insulation system for a state of moisture equilibrium. Water migrates from the cellulose insulation of the high moisture content to the synthetic ester which is subjected to continuous drying. The research was carried out on a complex laboratory model reflecting the transformer insulation system. In this model, the drying of the ester was carried out using a molecular sieve with an appropriately selected adsorber weight. To check the drying efficiency of the cellulose insulation, the water content in the pressboard strips taken from the model, both before and after the drying process, was determined. The water content was measured using the Karl Fischer titration method. The research showed the high efficiency of the proposed method of drying. With the ester moisture in the range of 110-130 ppm and the insulation system temperature of about 70 °C, the loss of water in the samples dried for 7 days was over one percentage point. The obtained test results constitute the basis for the validation of the method on distribution transformers.

7 citations

Journal ArticleDOI
TL;DR: In this article, thermally aged oil impregnated pressboard insulation, as barrier, have high impact on CIV and breakdown voltage, and the injected current due to corona activity, its rise time, measured using HFCT, in the negative and positive half cycle of the AC voltage measured to be 600 ps and 500 ps respectively.
Abstract: Corona Inception voltage (CIV) / breakdown voltage increases when the barrier is placed anywhere from needle tip to the 20% of the needle-plane electrode gap above which a marginal reduction in breakdown voltage is observed but its value is much higher than the breakdown strength of the electrode gap without barrier. Thermally aged oil impregnated pressboard insulation, as barrier, have high impact on CIV and breakdown voltage. The injected current due to corona activity, its rise time, measured using HFCT, in the negative and positive half cycle of the AC voltage measured to be 600 ps and 500 ps respectively. The shape of the current pulse is the same with the aged pressboard insulation barrier in the electrode gap. The corona inception voltage was measured by using UHF sensor and the signal has frequency contents between 0.5 -2.2 GHz. The surface charge measurements indicates that the amount of charge accumulated is high with thermally aged oil impregnated pressboard (OIP) than the unused material. Polarity of surface charge acquired by OIP due to corona charging depends on the surface condition of the material. To understand the mechanical behavior of the aged specimen, tensile test and flexural test were carried out and could conclude that ageing of material reduces the fundamental mechanical properties of the material. SEM analysis indicates that scission of fibers occurs due to thermal ageing at high temperatures. Partial Discharge studies on corona activity indicate, on corona inception, discharges occur near peak of the applied AC voltage, irrespective of position of barrier. The phase width of the PD generated due to corona discharge activity is slightly high with thermally aged specimen compared with unused specimen.

7 citations

Proceedings ArticleDOI
01 Oct 2014
TL;DR: In this paper, the effects of Kraft paper to prevent bridging in pressboard fibre contaminated transformer oil were investigated, and three different configurations of the Kraft paper were tested: covered electrode with loose bond, tight bond and bare electrode with a paper barrier in the middle.
Abstract: The paper investigates effects of Kraft Paper to prevent bridging in pressboard fibre contaminated transformer oil. There are three different configuration of Kraft paper tested. These are 1) covered electrode with loose bond, 2) tight bond and 3) bare electrode with a paper barrier in the middle. There were no bridges formed with loosely bonded tests with DC electric fields. For the other two cases, there was always a complete bridge formed.

7 citations

Proceedings ArticleDOI
C. Vincent1, N.G. Trinh1, R. Olivier1, J. Aubin1
05 Jun 1994
TL;DR: In this article, the behavior of an oil-paper interface in the presence of carbon particle contamination was investigated under AC voltage, where the carbon particles were deposited on and firmly fixed to the paper surface.
Abstract: The behavior of an oil-paper interface in the presence of carbon particle contamination was investigated under AC voltage. Influenced by an electric field perpendicular to the interface, the carbon particles are deposited on and firmly fixed to the paper surface. This constitutes an excellent means of reproducing particle contamination at the oil-paper interface, since it duplicates the particle-deposition mechanism in power equipment. Field deposition of carbon contamination was found to be reproducible and easy to obtain. On the other hand, a field parallel to the oil-paper interface tends to remove the contamination from the pressboard. The cleaning effect is sufficient to rapidly restore the dielectric performance of a carbon-contaminated oil-paper interface. >

6 citations

Proceedings ArticleDOI
01 Jun 2017
TL;DR: In this paper, the dielectric properties of the mineral oil, ELECTROL A, and the natural ester, FR3, are comparatively investigated, and it is found that the natural Ester shows superior dielectrics properties to the mineral Oil except the Dielectric dissipation factor.
Abstract: In this paper, dielectric properties of the mineral oil, ELECTROL A, and the natural ester, FR3, are comparatively investigated. AC breakdown voltages, dielectric dissipation factor, relative permittivity, partial discharge inception voltage and partial discharge of the mineral oil and of the natural ester are tested. In order to verify the capability in practical use of the mineral oil and the natural ester for transformer insulation systems, the impregnation of such liquids with pressboard insulation is performed. The impregnated pressboards are tested in the laboratory to measure the AC breakdown voltages. It is found that the natural ester shows superior dielectric properties to the mineral oil except the dielectric dissipation factor.

6 citations


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