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Kapton is a material developed by DuPont company. It is commonly used for insulation of electric and electronic devices. It offers excellent, physical, electrical, thermal and chemical resistant characteristics. It is a polyimide and it is usually available in a form of a homogeneous film wound onto a drum. In this work the Kapton tape is used within the layup of glass-epoxy (Letoxit LH198 resin, Letoxit EM231 hardener) braided composite tubes in order to increase the electrical insulation capability in case of high-voltage applications. The goal is to investigate the mechanical properties of three configurations of the braided tubes using four-point bending test and to mutually compare their stiffness and strength.

This publication was supported by the project TRIO FV30382 “Braided composite construction in electrical engineering – NAPREKON” of Czech Ministry of Industry and Trade, by the project LO1506 of the Czech Ministry of Education, Youth and Sports under the program NPU I. and by the project LO1607 of the Ministry of Education, Youth and Sports of the Czech Republic under the RICE – New Technologies and Concepts for Smart Industrial Systems.

Částečné výboje jsou jedním z nejčastěji se vyskytujících fyzikálních jevů, které mohou mít negativní vliv na celkovou životnost elektrických zařízení. Mezi nejzákladnější typy ČV (vedle povrchových a vnitřních) patří výboje vznikající v místech s malým poloměrem zakřivení. Při působení střídavého napětí jsou tyto jevy dobře známy. V oblasti stejnosměrných aplikací však stále existují výzvy. V tomto článku jsou představeny možné alternativní postupy a mechanismy pro diagnostiku výbojové činnosti způsobené stejnosměrným napětím. Partial discharges are one of the most commonly occurring physical phenomena that can have a negative effect on the overall life of electrical equipment. The most basic types (besides surface and internal) are discharges occurring in places with a small radius of curvature. At AC conditions, these phenomena are well know. However, there are challenges in the DC field. In this paper, the possible alternative procedures and mechanisms for diagnosing of the discharge activity caused by direct voltage are introduced.

This paper is focused on thermal aging and accompanied partial discharge diagnostics of two mainly used resin rich mica tapes, which are utilized as a part of insulation system of large rotating machines like turbo or hydro generators. The first tested specimen was mica composite material based on glass fibre and epoxy resin and the second one was composite based on PET and epoxy resin as well. The specimens were tested under laboratory conditions. The materials were thermally aged and the changes of its physical and chemical properties were measured and evaluated. For accelerating the aging process different temperature values (170 – 186 °C) were chosen. The aging time was determined for each temperature value. Specimens of tested material were performed and cured as flat plate 100×100 mm. The measuring of these specimens was carrying out by test voltage at special electrode test setup. For comparing the aging process of the investigated material the trends of measured partial discharge (pd) parameters (inception voltage, extinguish voltage, peak charge level) were studied and described in dependence on exposure time, temperature and applied voltage during measurement.

Částečné výboje, jejich měření a následná analýza, jsou jedním z důležitých a výpovědischopných nástrojů elektrotechnologické diagnostiky při hodnocení vlastností elektroizolačních systémů elektrických strojů a přístrojů. Částečné výboje jsou většinou analyzovány ve vztahu k fázi napájecího napětí, jejich četnosti, amplitudě zdánlivého náboje, apod. Nicméně v článku je studována možnost analýzy parametrů signálu jednotlivých pulzů částečných výbojů několika modelových uspořádání. Sledovanými parametry jsou náběžná doba a amplituda pulzu. Hodnocení souboru naměřených dat je řešeno aplikací histogramu pro oba měřené parametry.

V článku jsou nastíněny vytvrzovací pochody skloslídových kompozitů při izotermickém způsobu vytvrzování a kontinuální sledování ztrátového činitele v závislosti na teplotě a čase vytvrzování. Článek se věnuje studiu vytvrzovacího procesu dvou kompozitních materiálů: Relanex 45.011 a Relanex 45.031

Na izolaci transformátorů v provozu působí celá řada vlivů. Jedná se o komplexní působení, přičemž účinky jednotlivých degradačních parametrů se mohou vzájemně ovlivňovat. Pro každého uživatele a stroj je důležité sledovat jinou veličinu, jiný degradační činitel. Filozofie virtuálních měřících přístrojů umožňuje při zachování výkonostních parametrů klasické měřicí techniky vytvářet přístroje, jejichž funkce jsou realizovány softwarově a z tohoto důvodu přesně odpovídají požadavkům uživatele.

Neural networks represent a powerful means capable of processing various multi-media data. Two applications of artificial neural networks to 3D surface models are examined in this thesis - detection of significant features in 3D data and model classification. The theoretical review of existing self-organizing neural networks is presented and followed by description of feed-forward neural networks and convolutional neural networks (CNN). A novel modification of existing model - N-dimensional convolutional neural networks (ND- CNN) - is introduced. The proposed ND-CNN model is enhanced by an existing technique for enforced knowledge representation. The developed theoretical methods are assessed on supporting experiments with scanned 3D face models. The first experiment focuses on automatic detection of significant facial features while the second experiment performs classification of the models by their gender using the CNN and ND-CNN.

Dielectric subsystems have an important influence on reliability, lifetime and power of electrical equipments. Study of dielectric parameters and their changes due to degradation mechanisms provide important information about the equipments. Paper deals with oil-paper systems and their thermal degradation. These systems are used for example in transformer, capacitors and bushings. Thermal degradation causes increasing of moisture content thus number of polar particles. Therefore the main idea of this paper is diagnostic of oil-paper insulation based on a method of polarization measurement. One of the methods is Cole-Cole diagram [1] or its modification e.g. Davidson [5], Havriliak-Negami [11]. The next aim of the paper is measurement of the system parameters (Complex permittivity, Viscosity, Acid value, Resistivity, Polarization index and Dissipation factor) and their changes due to thermal degradation. In experiments are used a normal and an environmental friendly fluid.

This thesis examines existing algorithms for solving the problem of the longest common subsequence. It tries to apply them to the problem of effective archiving of data which differ a little, because they are, for example, just versions of one file. There are also new methods suggested. Those are based on the examined algorithms. Then the algorithms are compared according to the reached results and their running time.

Usage of the modern power electric drives brought advantages in induction motor control. In the same time problems with "pulse stress" produced by the voltage converters appeared. The converters produce repetitive pulses with the high level of voltage rise fronts (slew rates). Rise fronts attained values of up to tens kilovolts per microsecond and voltage pulse repetition frequency up to some tens of kilohertz. However, this technology is an advantage for a drive control; the voltage waveforms generated by power frequency converters may affect significantly the reliability of the electric motor insulation systems. This study is presenting observation of the aging by the high frequency square waveform voltage of frequently used slot insulation. For the studying slot insulation aging process under pulse voltage were chosen partial discharge parameters: the partial discharge inception voltage (PDIV), partial discharge activity level and partial discharge phase resolved characteristics.

The voltage waveforms generated by power frequency converters affect significantly the reliability of drive wall insulation. A power inverter produces modulated voltage on its output which contains square-shaped voltage impulses with fast rise times. This allows controlling the drive speed and torque, but in the same time it has significant effect on the wall insulation reliability. This type of voltage rapidly ages the insulation system. This leads to the breakdown of insulation which means the drive failure. The problem is to predict the machine wall insulation lifetime, when it operates as a part of the power inverter fed drive. The main goal of the research project was to provide quantification of the wall insulation reliability decrease. Insulation systems were laboratory aged both, by the ac 50 Hz voltage and high frequency pulse voltage (slew rate 16 kV/mus). The life time curves have been evaluated and simple mathematical models have been employed to show the wall insulation reliability decrease. The results will be used in a new more accurate aging models designing.