Topic
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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TL;DR: In this paper, the authors performed an experimental investigation under an AC step test voltage to analyse the effects of the structure, distance and gluing direction of pressboard on creepage propagation, and the results of this preliminary investigation may be useful for improving the dielectric creepage strength of solid insulation systems using pressboard as radial spacers, and highvoltage winding lead support parts.
Abstract: One of the vital causes of the failure of oil transformers is considered as the creepage discharge propagation on pressboard. The authors performed an experimental investigation under an AC step test voltage to analyse the effects of the structure, distance and gluing direction of pressboard on creepage propagation. Flat, ribbed and grooved test specimens were prepared. Further, breakdown experiments were conducted for two gluing directions, parallel and vertical with respect to the electric field. For parallel gluing, the average breakdown voltage (V BD) of the ribbed and grooved types was 1.2–1.33 times that of the flat type. For vertical gluing, the V BD of the flat type was 1.28–1.66 times that of the same type with parallel gluing, whereas the values for the ribbed and grooved types were 1.02–1.11 times the corresponding values for parallel gluing. The rib height and groove depth do not seem to contribute greatly to the breakdown strength because most of the flashover propagation appeared not on the pressboard's surface but at the glued interface. The results of this preliminary investigation may be useful for improving the dielectric creepage strength of solid insulation systems using pressboard as radial spacers, and high-voltage winding lead support parts.
4 citations
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01 Sep 2011
TL;DR: In this paper, the effect of temperature on the frequency domain spectroscopy (FDS) test results of transformer oil-paper insulation and for accurately assessing the aging condition and moisture content in pressboard, FDS experiments are performed on the oil-impregnated sample at different temperatures.
Abstract: To investigate the effect of temperature on the frequency domain spectroscopy (FDS) test results of transformer oil-paper insulation and for accurately assessing the aging condition and moisture content in pressboard, FDS experiments are performed on the oil-impregnated pressboard sample at different temperatures. The temperature effect on the dissipation factor tanδ, real capacitance C′ and imaginary capacitance C″ of the oil impregnated pressboard in frequency domain ranging from 1 mHz to 1 kHz are analyzed. The results show that, tanδ, C′ and C″ obviously increase in lower frequencies range while having no obvious increment in higher frequencies when measurement temperature rises. Moreover, with the increasing of temperature, both tanδ and C″ curves shift to the higher frequency, while the minimum values of tanδ and C″ increase slightly. The frequency range where C′ changes rapidly, shifts to higher frequencies. It is revealed that temperature has a significant impact on the FDS test results. At higher temperatures, based on the FDS results, the conductivity of oil-paper insulation and the evaluated moisture content of pressboard will be higher, and lead to a more serious aging judgment for on-site transformer solid insulation.
4 citations
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11 Jun 1984TL;DR: In this article, the electric field enhancement in the liquid alone (due to space charge) is compared with the enhancement with interfaces installed, which serve to better define the roles of space charge and interfacial surface charging in pressboard/transformer oil highvoltage systems.
Abstract: Electro-optical Kerr-effect measurements are made to characterize the electric field in the vicinity of pressboard interfaces in transformer oil. The interfaces are placed between parallel plate electrodes and are oriented parallel to the field direction and in contact with bath electrodes. The electric field enhancement in the liquid alone (due to space charge) is compared with the enhancement with interfaces installed. These results serve to better define the roles of space charge and interfacial surface charging in pressboard/transformer-oil high-voltage systems.
4 citations
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01 Jun 2014TL;DR: In this article, the authors focused on the route of discharge progress along the pressboard barrier and evaluated the discharge velocity as well as the time required for the successive discharge generation across the barrier.
Abstract: It is crucial for reasonable transformer insulation design to understand the characteristics of discharge progress under the application of a standard lightning impulse voltage. This paper deals with the fundamental discharge characteristics of oil/pressboard (PB) composite insulation system. We obtained discharge images using a digital camera equipped with an image intensifier. In this research, we focused on the route of discharge progress along pressboard barrier. Furthermore, we evaluated the discharge velocity as well as the time required for the successive discharge generation across the barrier PB.
4 citations
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17 Jan 2013
TL;DR: In this article, an electrical device (4) comprising a cellulose based electrically insulating composite material (1) in the form of a paper or pressboard, the composite material comprising: cellulose fibres; and a thermoplastic polymer material; wherein the polymer material is arranged around and between the cellulose fibers, and binds said fibres to each other.
Abstract: The present disclosure relates to an electrical device (4) comprising a cellulose based electrically insulating composite material (1) in the form of a paper or pressboard, the composite material comprising: cellulose fibres; and an electrically insulating thermoplastic polymer material; wherein the polymer material is arranged around and between the cellulose fibres, and binds said fibres to each other.
4 citations