Paper presents experimental diagnostics of insulating system oil-paper for power transformers, mainly by progressive frequency method – dielectric spectroscopy. The introduction of the article is described the base analyzing for measurement insulating elements (oil and paper) of power transformers. The next part of article is described application of dielectric frequency domain spectroscopy (FDS) method for high-voltage power transformers. Diagnostic methods are used for measurement of insulating state of high-voltage devices with insulating parts as oil-paper. It was present that the values of these measuring results are highly impacted by the temperature of operating during the experimental diagnostics. Conductivity and moisture between dielectric transformer paper and insulating oil in a dielectric system are highly dependent from internal and ambient temperature. In the final section the article are presented experimental values of the diagnostic analysis for an operating oil traction transformer at different internal temperatures and conditions (with oil filling and without).
The paper presents results of experimental investigations of fatigue behaviour of thin-walled integrally stiffened plates. Structures under consideration was treated as the skin part of the semi-monocoque construction and subjected to shear load what led to the post-buckling state of deformation. Tested plate was manufactured as an integral construction from 2024-T3 aluminium alloy with use of the CNC milling machine. Experimental results of preliminary static test in the form of displacement fields obtained by the digital image correlation method were compared to the results of numerical calculations. On the basis of this comparison, the correctness of the stress distribution obtained by numerical method was found and the load level for fatigue test was chosen. The conducted experimental tests showed a significant influence of the stiffener arrangement on the form of fatigue failure.
The surface roughness of the parts has a significant influence on their performance properties and it is crucial for the friction force and wear of the bodies. Therefore, in practice it is often necessary to perform finishing treatment to reduce the macro, micro and mesoroughnesses grinding, honing, lapping, polishing and more. In this study are examined the possibilities of reducing the roughness and the traces of the previous machining of steel surfaces by electro-spark deposition (ESD) with lowmelting aluminium alloys. The roughness of the steel surfaces obtained after different milling modes after subsequent electrospark coating was investigated. Dense and uniform coatings with different surface microgeometry are obtained, which to a different extent erase the traces of the preceding processing. The examination of tribological characteristics showed a significant increase in the wear resistance of the coated surfaces. The process parameters and materials for ESD at which coated surfaces have simultaneously the lowest roughness and the highest wear resistance have been determined and optimized.
This paper analyzes the problems of thermal measurement of electrical machines using thermovision diagnostics. It examines the experimental principles and uses of noncontact temperature measurement for diagnostics. The knowledge of the problem diagnostics of electrical machines in service without disassembly enables us to use more efficient thermo-diagnostic methods and to localize the failures that determine the quality of electrical machines.
This work provides an overview of the technological features of additive technologies for manufacturing metal parts and products (3D printing metals). The nature and types of printing, perspectives, and opportunities for their development are indicated. The advantages and disadvantages of additive technologies are clarified. An analysis of the technological process parameters has been made, on the basis of which the main problems hindering its mass introduction in the industry have been identified. The main dependencies of the quality and properties of the manufactured parts on the process parameters are given, and ways of avoiding and eliminating the defects are presented.
Implementation of interoperable devices, as they are used in IIoT and Industry 4.0 networks, is currently a time consuming and difficult work. This article describes methods and technologies for improving the efficiency of this process. The approach proposes to define data structures, groups of equipment component variables and later on component descriptions by use of formal languages. Further on, forms-based on-line editing of specifications is proposed instead of using word processing software. Code generators are then introduced to transform the formal descriptions into parts of the firmware code of the IIoT devices. The proposed approach provides support for standardization organizations and equipment manufacturers.
