0000000000798154
AUTHOR
Dariusz Zmarzły
The possibilities of using the acoustic emission method in expert systems for the evaluation of insulation systems of power transformers
The paper presents the range and possibilities of using expert systems at diagnostic measurements of insulation systems of power appliances taken by the acoustic emission (AE) method. Multi-parametric descriptors characterizing the AE signals, which can be used in the knowledge base as criteria making the identification of basic partial discharge forms (PDs) possible, have been characterized in detail. The tables show descriptors describing the AE signals registered in time, frequency, time-frequency domains and statistical data. Moreover, computational tools that can be used in the process of conclusion drawing were suggested and the range of the research work done by the authors of the pa…
ECT of ethanol and hexane mixtures in the spinning disk system
The paper presents the research results of electrostatic charging tendency (ECT) of ethanol and hexane mixtures, a liquid of a simple chemical structure and high purity (pro analysis). The research work was carried out in a spinning disk system, where the factors influencing the value of the electrification current registered were the composition of the mixture and the rotational speed of the disk. The research results showed that the biggest ECT changes occur in the range of up to 10% of ethanol content in hexane and the electrification current characteristic has a visible maximum for the mixture, the contents of which constitute 95% of hexane volume and 5% of ethanol by volume. In the nex…
The analysis and selection of the spinning disk system parameters for the measurement of static electrification of insulation oils
The paper presents results the aim of which was determining the most favorable conditions of ECT (electrostatic charge tendency) measurement taking of insulation oils in the spinning disk system. The work proved that a proper selection of the size and roughness of the disk surface makes the measured volume density of charge qw independent of the hydrodynamic conditions in the measuring system on the solid and liquid phase border. Charge qw density meets then the criterion of a material coefficient and can be used for comparing the results obtained from the systems varying in dimensions and hydrodynamic conditions. The changes suggested also ensure a high repeatability and reproducibility of…
Biochar and Forage Peanut improve pastures: Evidence from a field experiment in Brazil
Pasturelands, often degraded, represent most of the converted lands globally. It is important to understand how different pasture management approaches can improve soil quality, increase feed production and farmer income. Here, the impact of different soil enhancers on soil quality and productivity of three cultivars of Brachiaria (Syn. Urochloa) forage grass is presented. Soil enhancers included: biochar - a carbon-rich product from biomass pyrolysis, moinha (local charcoal residue), traditional fertiliser containing nitrogen, phosphorus and potassium, lime, and forage peanut (Arachis pintoi cv. Amarillo). Considering the total biomass produced over the experiment (sum of four harvests), t…
A noise analyzer for monitoring static electrification current
Abstract This paper presents a static electrification current signal analyzer used for measuring and processing of the variable component of the changes in electrostatic charge that occur on a solid-body/liquid boundary interface. Due to high sensitivity and low uncertainty, the analyzer allows a precise evaluation of the phenomenon generated. The device operates in a spinning-disk system. The tests carried out indicate that it is possible to measure random components which depend, to a large extent, on hydrodynamic conditions and on the properties of the liquid phase. The device can be applied to the testing of transformer oils. It can be also used for measurements of other liquids having …
Application of wavelet analysis to acoustic emission pulses generated by partial discharges
The subject matter of this paper refers to the improvement of the acoustic emission (AE) method when used for detection, measurement and location of partial discharges (PDs) in oil insulation systems of power appliances. The detailed subject matter refers to the issues connected with the application of modern methods of digital processing of signals obtained during technical high-power measurements. The paper presents the results of measurements and analyses of the AE pulses generated in setups making the modeling of basic PD forms that can occur in oil insulations possible. The research concentrated mainly on the following types of PDs: point-plane, multipoint-plane, multipoint-plane with …