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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21 Jul 1995
TL;DR: In this article, a current-carrying heating element which is heated by application of voltage to a resistor composed chiefly of a composition wherein an electricaly conducting material is dispersed in an organic high polymer is made from polyether ketone (PEEK) and a resin whose melt viscosity is 10 -10 poise at a temperature of 380 deg.C and at a shear rate of 10 s.
Abstract: PURPOSE:To provide a self-temperature controlling, current-carrying heating element having a good temperature distribution with a heating temperature of 150 deg.C or higher and therefore a long load life by composing a resistor chiefly of a composition wherein an electrically conducting material is dispersed in an organic high polymer of a specific characteristic. CONSTITUTION:In a current-carrying heating element which is heated by application of voltage to a resistor composed chiefly of a composition wherein an electricaly conducting material is dispersed in an organic high polymer, the organic high polymer is made from polyether ketone (PEEK) and a resin whose melt viscosity is 10 -10 poise at a temperature of 380 deg.C and at a shear rate of 10 s . Polyphenylene sulfide(PPS), polyether imide, or polyether sulfone is used as such a resin. The electrically conducting material added to the organic polymer is carbon black, graphite, or preferably MnZn ferrite. The conducting material is kneaded and dispersed by 50vol.% in the organic high polymer (PEEK/PPS=6/4) to form a pressboard, and electrodes are bonded to both sides of the pressboard and voltages are applied to the electrodes for heating.
4 citations
TL;DR: In this paper, the short-circuit axial vibration of a 250 Mva 500 kV single phase shell form transformer is calculated for various design and operating conditions, and it is shown that friction in the interleaved core joints is sufficient to prevent core separation.
Abstract: The short-circuit axial vibration of a 250 Mva 500 kV single phase shell form transformer is calculated. The displacements of the coils and the stresses on the pressboard insulation between the coils are found for various design and operating conditions. Three different lumped mass models with nonlinear press-board representation are used for calculating the vibration in various parts of the coils because the frame which backs up the coils during short circuit is nonuniform. In shell form transformers manufactured by the authors' company the frame consists of both the core and the tank which have considerably different mechanical impedances. These impedances are shown to be quite important and methods for evaluating them are given. The impedance of the tank is determined from the results of tests of a 1/7 scale model. The results show that dynamic effects are not large. The maximum calculated pressboard stress is 2290 psi (15790 kPa), which is only 27% higher than the statically calculated stress; and the maximum calculated coil displacement is .87 inch (2.21 cm). It is also found that friction in the interleaved core joints is sufficient to prevent core separation.
4 citations
01 Oct 1962
TL;DR: In this paper, the authors deal with flashover in oil between electrodes mounted on pressboard sheets, puncture and flashover of precompressed board, flashoff in the presence of stress normal to the pressboard surface, breakdown between covered conductor in contact, or separated by packing pieces, or separating by barrier sheets.
Abstract: The paper deals with flashover in oil between electrodes mounted on pressboard sheets; puncture and flashover of precompressed board; flashover in the presence of stress normal to the pressboard surface; breakdown between covered conductor in contact, or separated by packing pieces, or separated by barrier sheets; flashover of an interrupted surface; and flashover between electrodes passing through bushes in a pressboard sheet. It also contains comparative data on breakdown voltages at room temperature and at 90°C, in elected arrangements.
4 citations
04 Oct 1993
TL;DR: A comparison of the physical properties of three varieties of material used as pressure rings to clamp and hold the coils of core-form oil filled transformers is given in this article, with a brief history of the development of the three systems, along with a list of the features of each material and general information regarding applications relative to transformers ratings.
Abstract: A comparison of the physical properties of three varieties of material used as pressure rings to clamp and hold the coils of core-form oil filled transformers is given. The data is presented to serve as a guide in the selection of materials for pressure ring applications. The materials studied are polyester bonded high density pressboard, epoxy bonded electrical steel and epoxy bonded filament glass. A brief history of the development of the three systems is presented, along with a list of the features of each material and general information regarding applications relative to transformers ratings.
4 citations
01 Jan 2012
TL;DR: In this paper, the dielectric response characteristics of the actual large oil-paper insulation power transformer were studied on the basis of dielectrics theory, and the test results show a strong regularity that frequency, temperature, and moisture content effect on the response curve of large power transformer.
Abstract: The dielectric response technology is a nondestructive technology of moisture content diagnosis for oil-paper insulation by dielectric response curveTo promote the development and application for the dielectric response technology,the dielectric response characteristics of the actual large oil-paper insulation power transformer were studied on the basis of dielectric theory,and the test results show a strong regularity that frequency,temperature,and moisture content effect on the dielectric response curve of large power transformerThe qualitative analysis method of moisture content in oil-paper insulation for the large power transformer was proposedThe quantitative analysis method of moisture content in oil-paper insulation of the large power transformer was developed based on the equipment X-Y model and the complex permittivity database of oil impregnated pressboard under various moisture contents and temperatures,and the calculated values agree with the experimental data approximately
4 citations