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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 article, the effect of multilayers and thickness on space charge behavior of oil and pressboard insulation system was measured using the pulsed electroacoustic technique (PEA) method.
Abstract: Space charge build-up has been considered as the major issue in the development of HVDC apparatus such as the converter transformer. The existence of space charge can distort the local electric field, which could lead to the degradation and even breakdown of insulation materials. Therefore, it is vital to investigate factors that can affect space charge formation and dissipation characteristics such as the temperature, moisture, ageing, thickness, multi-layered structure and electric fields. This paper mainly focuses on the effect of multilayers and thickness on space charge behaviour of oil and pressboard insulation system. Space charge was measured using the pulsed electroacoustic technique (PEA) method. The space charge results are quantitatively analysed to establish the relationship between interfacial charge density and different pressboard and oil thickness ratios. A new space charge interpolation methodology is utilized to input space charge into the multilayers oil and pressboard model using COMSOL software. The local electric field of multilayers oil-impregnated pressboard and oil could be simulated, with the emphasis on the electric field after the polarity reversal operation. From space charge results, they indicate that the increased thickness of pressboard could prohibit the interfacial charge increase while the increased oil thickness could facilitate interfacial charge increase. Moreover, from the electric field simulation results, they indicate that there is the electric field gradient caused by the space charge for multilayers oil and oil-impregnated pressboard structure. After the polarity reversal, the maximum electric field of the oil caused by the space charge is higher than electric field calculated based on the Maxwell-Wagner theory.

13 citations

Journal ArticleDOI
TL;DR: In this article, the authors used two different test pipes, one made of pressboard and the other of insulating paper, to investigate streaming electrification under dc and ac electric fields by using test pipes and oil circulation apparatus.
Abstract: Streaming electrification under dc and ac electric fields was investigated by using test pipes and oil circulation apparatus. We used two different test pipes, one made of pressboard, and the other of insulating paper. At first, the amount of static charges which flowed into the test pipes was measured without electric field. For the experiment using an insulating paper pipe, when the oil temperature increased, the measured current curve shows a peak. When the velocity increased, the current increased proportionally from the 2nd to 4th power of velocity. For the experiment using a pressboard pipe, the current increased proportionally from the 3rd to 5th power of temperature, and by the 1st power of velocity. Then, we applied ac and dc electric fields on the test pipes and the current from a relaxation tank to ground was measured. The ions in oil carry the charges, so an electric field affects ions in the oil. It makes the mathematical approach to streaming electrification difficult. We know that as the electric field intensity increased, the current due to selective adsorption of the test pipe was increased. The current vs. velocity curve under ac electric field had a peak point in velocity.

13 citations

Proceedings ArticleDOI
01 Oct 2006
TL;DR: In this article, the authors present the lightning impulse voltage test results of service-aged pressboards taken from a failed power transformer after 29 years' service and reveal that there is a significant reduction of breakdown voltages, most probably due to the degradation of mechanical strength.
Abstract: This paper presents the lightning impulse voltage test results of service-aged pressboards taken from a failed power transformer after 29 years' service. Impulse voltage tests have revealed that there is a significant reduction of breakdown voltages, most probably due to the degradation of mechanical strength. The minimum impulse electric strength may reduce approximately by 30% after 29 years' service. Test results on the service-aged pressboard also indicate that when the moisture content in pressboard is less than 4%, there is no significant correlation between the reductions of the impulse electric strength with increasing moisture content.

13 citations

Journal ArticleDOI
TL;DR: In this article, the effect of nanoparticles shapes on creeping flashover characteristics at the interface of nanofluid-impregnated pressboard (NP) was investigated and the results showed that the modifications by spherical and rod nanoparticles have a specific surface area 13 times as large as that of nanorods at the same concentration, and it is a source of shallow traps.
Abstract: Recent studies have shown that the modifications to nanofluid-impregnated pressboards by different shapes of nanoparticles are different To investigate the effect of nanoparticles shapes on creeping flashover characteristics at the interface of nanofluid-impregnated pressboard (NP), creeping flashover behavior of spherical nanoparticle fluid/pressboard (NSFP) and nanorod fluid /pressboard (NRFP) were compared to that of oil/pressboard (OP) which was used as a reference Creeping flashover experiments under AC and positive and negative impulse voltages were carried out Results show that the modifications by spherical and rod nanoparticles on creeping flashover strength are distinct and different: negative creeping flashover voltages of NSFP and NRFP are increased up to 32 and 15% respectively, and the positive ones are separately improved as high as 15% and 5% Whereas, experiments under AC voltage reveal quite a different trend: creeping flashover voltage of NSFP and NRFP are almost increased to the same extent, nearly 18%, while partial discharge inception voltage improvement in the increment of the former is 56 times larger than that of the latter Charge behaviors at oil/pressboard interfaces were displayed by thermally stimulated depolarization current method Space charge accumulation at the surface of NSFP is much less than that of NRFP and the dissipation rate of the former is faster, due to a larger trap density and a lower trap energy level, which weakens electric field distortion and results in the improvement of creeping flashover strength The underlying mechanism is that spherical nanoparticles have a specific surface area 13 times as large as that of nanorods at the same concentration, and it is a source of shallow traps

13 citations

Journal ArticleDOI
02 Jul 2019-Polymers
TL;DR: The present findings reveal that the αT value extracted from FDS curves is both temperature-dependent and moisture-dependent, and will provide a universal method for temperature correction on FDS curve of transformer polymer insulation.
Abstract: It is a fact that the frequency domain spectroscopy (FDS) curve at different temperatures can be corrected by the shift factor (αT) extracted from the master curve. However, the αT and master curve reported by previous works are distinctive due to the difference in the construction algorithm. Therefore, it is of great significance to report a universal approach for extracting αT. In this work, the unaged oil-immersed pressboards with different moisture content (mc%) are firstly prepared and selected as the research specimen. Then, the αT of FDS curves on the above pressboard is extracted based upon the master curve technique. The influence mechanism under the various test temperature (T) and mc% is therefore analyzed so as to establish a universal model for predicting the αT. The present findings reveal that the αT value extracted from FDS curves is both temperature-dependent and moisture-dependent. In addition, the predicted αT is not only suitable for temperature correction on FDS curve of same type pressboard with different insulation conditions (moisture contents and aging degrees), but also maintains considerable accuracy when applied to different types of pressboard. Therefore, the obtained conclusions will provide a universal method for temperature correction on FDS curve of transformer polymer insulation.

13 citations


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