| Working Modes of a Transformer |
| Simona Filipova-Petrakieva |
|
Abstract: The main function of the transformer is to convert AC voltage from one value to another. Its normal working mode is to increase or decrease the AC voltage. When its primary and secondary windings have equal turns, it is used to galvanically separate of the consumer from the power supply. Depending on the connection of the secondary winding to the load, it works in modes of increasing or decreasing the output voltage - booster or buck transformer, respectively. In these modes, the design of the transformer ensures less power than in normal use. It is absolutely forbidden to connect the primary and secondary windings to the power supply in parallel each other and in parallel of the supplied voltage without reactive passive elements in series of them. This is only possible for primary and secondary windings with equal number of turns. In the present work, a detailed analysis of these modes is provided. The stress is on their specific character. Keywords: working modes of transformer – accepted and unaccepted, booster transformer, buck transformer |
| DOI: 10.47978/TUS.2024.74.02.001 |
| Analysis of Innovative Methods for Forming Voids in High Pressure Castings |
| Ivan Ivanov |
Abstract: The study is about some promising and innovative methods giving new possibilities for the application of the high pressure casting process. The main goal is to evaluate the possibilities of the considered methods for their application in the production of details for the automotive industry. This type of detail is characterized by a complex shape and high quality requirements. The industry itself requires them to be increasingly complex and sophisticated, which places new tasks on technological processes and methods. The need to make a part that combines the functions of several requires it to have closed cavities - surfaces and elements of geometry that cannot be formed with traditional permanent forms. The construction of such tools usually provides for removal by means of mechanically driven elements, which in almost all cases have a rectilinear movement. This, in turn, drastically limits the possibilities regarding the complexity of the shaded area. Another object of the methods is to obtain castings that have internal channels for transfer of working pressure or tempering hydraulic fluid. Keywords: High Pressure Die Casting, Dies, castings, aluminum alloys, molded-in-inserts, shaded areas, channels of complex shape, automotive industry, electric vehicles, batteries, salt cores |
| DOI: 10.47978/TUS.2024.74.02.002 |