JOURNAL / ISSUES ISSN 2310-6697 / ISSN-L 2310-6697 |
open transactions on independent scientific-engineering research |
FUNKTECHNIKPLUS # JOURNAL |
Théorie-Expérimentation-Métrologie-Logiciel-Applications |
ISSUE 6 - SATURDAY 31 JANUARY 2015 - YEAR 2 |
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PAPERS |
Attribution 4.0 International License CC BY 4.0 |
6-1 |
# Telecommunications Engineering - Logiciel |
Visual EM Simulator for 3D Antennas: VEMSA3D - FLOSS for MS Windows |
C. A. Koutsos, N. I. Yannopoulou, P. E. Zimourtopoulos |
ABSTRACT |
This paper introduces the FLOSS Free Libre Open Source Software [VEMSA3D], a contraction of "Visual Electromagnetic Simulator for 3D Antennas", which are geometrically modeled, either exactly or approximately, as thin wire polygonal stru-ctures; presents its GUI Graphical User Interface capabilities, in interactive mode and/or in handling suitable formed antenna data files; demonstrates the effectiveness of its use in a number of practical antenna applications, with direct comparison to experimental measurements and other freeware results; and provides the inexperienced user with a specific list of instructions to successfully build the given source code by using only freely available IDE Integrated Development Environment tools—including a cross-platform one. The unrestricted access to source code, beyond the ability for immediate software improvement, offers to independent users and volunteer groups an expandable, in any way, visual antenna simulator, for a genuine research and development work in the field of antennas, adaptable to their needs. |
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6-2 |
# Electrical Engineering - Expérimentation |
Diagnostic Techniques in Transformer Oils: Factors Affecting the Lifetime of Transformer Oil in Transformers of 150/20 kV and the Problem of Relating Diagnostics Data with their Pre-history |
M. G. Danikas, S. Georghiou, I. Liapis, A. B. B. Abd. Ghani |
ABSTRACT |
The aim of this paper is the study of various parameters affecting the lifetime of transformer oil in transformers of 150/20 kV. Fifty (50) samples of oil were taken from such transformers in the major Athens area, Greece. The parameters investigated – according to international standards – were breakdown strength, oil color, humidity, interfacial tension and tanδ. Thermal and mechanical stresses have as result the oxidation of transformer oil and the deterioration of its insulating properties. Humidity and foreign particles also consist factors contributing to the lowering of the breakdown strength of transformer oil. In most examined samples the breakdown strength and tanδ were satisfactory. It is shown that the slightest contact with the atmospheric air may affect humidity. A color index of 3 does not necessarily mean that the oil is bad. Foreign particle presence combined with humidity may decrease the interfacial tension. Generally speaking, the 50 investigated transformers were in a satisfactory state and none of them was required to have its oil replaced. A main conclusion of this work is that we should not base our judgment about the oil quality on only one or two parameters but on a combination of more parameters. |
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