Pressboard

About: Pressboard is a research topic. Over the lifetime, 1123 publications have been published within this topic receiving 9089 citations.

Analysis of frequency domain spectroscopy measurements on power transformers by the use of a Finite Element based model

Abstract: Dielectric spectroscopy (FDS) is widely used to assess the condition of transformer oil-paper insulation systems Typically the frequency dependent complex capacitance C HL between the high- and low-voltage windings is measured This capacitance can be modeled analytically using simple RC-equivalent circuits, due to the homogenous electrical field distribution in the main insulation duct (XY or Pancake-model) [2] A curve fitting of this model to the measured data enables extraction of dielectric parameters like oil conductivity and moisture content in pressboard Apart from C HL it is also possible to measure the complex capacitance between HV windings and tank (C H ) where we also have an oil-paper insulation system The corresponding measurement data can't however be fitted to the conventional Pancake-model, because of the inhomogeneous field distribution between HV windings and tank Hence a Finite Elements Analysis (FEA) based model which describes the dielectric behavior of the transformers isolation system between HV windings and tank was developed in this paper This numerical model was combined with an optimization algorithm to determine the unknown dielectric parameters from dielectric spectroscopy data for C H FDS measurements of C H and C HL from three power transformers were analyzed by the use of the conventional Pancake-model for C HL and the new FEA-model for C H The results showed good agreement in dielectric parameters of oil and pressboard what leads to a strong verification of dielectric diagnosis results for a transformer by two independent models and measurements

Floor conveying device of plywood cold press

Abstract: The utility model provides a floor conveying device of plywood hot press breaks through traditional plywood hot pressing conveying equipment's structural form, at the real work in -process, the utility model discloses carry the template embryo to the hot press. Specifically be, operate mobilizable base and move movable support, make each loading board and each layer of hot press add the hot pressboard one -to -one, corresponding drive arrangement drive is afterwards removed to bear to drive and is supported template embryo towards the hot press horizontal migration that top component and eachloading board bore, make accurate the stretching into of template embryo add in the hot pressboard, and bear the weight of the template embryo at the loading board and get into the in -process with the hot pressboard gradually, the loading board can be released existing moulded plywood in adding the hot pressboard, make new template embryo alternate, the frame is born the weight of to keeping awayfrom the hot press under corresponding drive arrangement's drive to the activity, and each loading board is withdrawn from from the below of template embryo gradually, and each template indusium is replaced the horizontal pole and is blocked and stop corresponding with in the hot pressboard.

Heat characteristic measuring device for cloth

Abstract: PURPOSE:To verify optimum press conditions with an expression, etc., by measuring the heat characteristic of a cloth in match to the real states of a heat, a moisture and a dryness which the cloth receives the press process of a sewing. CONSTITUTION:A cloth to be measured is held by a chuck 1 to add a displacement gage and a servo motor 8 and a chuck 2 to add a force gage 9 through a space between an upper pressboard 4 and a lower pressboard 6. A control board 12 incorporating a microcomputer connected to a thermocouple 10 arranged on the cloth pressing surface of the lower pressboard 6 and a control board 13 connected to the servo motor 8, displacement gage 7 and force gage 9 are provided, and shrinkage under a stress change applied to the cloth at the time of a drying or heating press, the temperature behavior of the cloth and the initial tention of the cloth after a press completion are automatically measured.

Statistical analysis of oil percolation through pressboard measured by optical recording

Abstract: The paper presents a measuring station used to measure the percolation of transformer oil by electrotechnical pressboard. Nytro Taurus insulating oil manufactured by Nynas company percolation rate by the Pucaro company pressboard investigation was made. Approximately 60 samples of Pucaro made pressboard, widely used for insulation of power transformers, was measured. Statistical analysis of oil percolation times were performed. The measurements made it possible to determine the distribution of capillary diameters occurring in the pressboard.

Dielectric properties of coconut oil impregnated pressboard samples

Abstract: Coconut oil has been reported as a potential alternative for mineral oil when used as the power transformer liquid insulation. However, the information on dielectric properties of coconut oil impregnated transformer solid insulation i.e. paper and pressboard are still lacking. This paper presents variations of capacitance and dielectric losses of coconut oil and mineral oil impregnated pressboard samples during oven heating. First 24 pressboard samples having either 2% or 4% moisture contents were prepared. Then the samples were impregnated by coconut and mineral oil (half each) and the samples were dried inside two ovens over 800 hours at two different temperature (110 °C and 130 °C) levels. The dielectric properties were obtained by Frequency Domain Dielectric Spectroscopy (FDS) measurements. The results showed that in both coconut oil and mineral oil impregnated pressboard samples, capacitance and dielectric losses increased with heating time, temperature level and initial moisture content. Further the losses were relatively higher for coconut oil impregnated pressboard samples in comparison to mineral oil.