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Synergic effects of multistress ageing of electroinsulating materials
Novák, Lukáš ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
Submitted work deals with monitoring impact of thermal and electric ageing on the dielectric properties of insulating material NKN 0887. In the course of the experiment five sets of dielectric insulating materials were aged. The voltage range has been set from 1,5 kV till 2,2 kV and temperatures were 23 °C and 200 °C. The capacity and loss factor has been directly measured by RLC meter Agilent with attached electrode system. The electrode system operates on the principle of a plate capacitor. The values of relative permittivity and loss number has been calculated from values of capacity and loss factor. For easier confrontation has been frequency dependences of these values plotted in a chart. The Cole-Cole diagrams has been created and factors of Havriliak-Negami function has been calculated. Data has been compared with each other and the effect of ageing factors has been deduced.
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Investigation of high voltage influence on different materials in high and low vacuum
Šedivý, Matúš ; Šandera, Josef (referee) ; Hejátková, Edita (advisor)
The beginning of this thesis contains an overview of properties of the insulators, and description of insulators that were used for in depth research of surface breakdown in vacuum. Furthermore, this work focuses on mechanisms of an electric breakdown initiation at the interface of the solid insulator and surrounding low pressure gas. Multiple methods for measurements of dielectric strength are examined. The experimental part describes the measurements performed in the vacuum chamber. The results of these measurements are then analysed. In conclusion, used insulators are compared and suggestions for further work are given.
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Ex-Situ Xrd Characterization Of Electrodes For Electrochemical Power Sources
Klvač, Ondřej
The article describes a theoretical method of a research of graphite electrodes in an electrochemical cell where the problem is with the preferred orientation and a thin layer. As a result, only a reflection (002) is visible. However, there is a possibility to determine crystallographic parame-ters from these peaks because of the effect of a destructive and constructive interference caused by intercalated lithium atoms. At the same time, the work shows that Kapton is not a suitable material for ex-situ cell production, as samples have been destroyed by air humidity. Finally, a circular ex-situ cell was made and tested with the pure sodium. This modification reduces a rate of degradation of the samples.
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Tracking Resistance Of
Various Materials In Vacuum
Šedivý, Matúš
Many vacuum instruments used in industry and scientific research apply high voltage components. Vacuum performs as an insulator with theoretically infinite breakdown voltage. Surface of dielectrics between two electrodes inside a vacuum chamber is the weakest link for a possible electrical breakdown (tracking). This paper focuses on examination of a vacuum pressure influence to the surface breakdown voltage of a various materials. Results were compared and led to determination of an appropriate materials for a design of internal connectors in electron microscopes produced by the company Thermo Fisher Scientific.
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Investigation of high voltage influence on different materials in high and low vacuum
Šedivý, Matúš ; Šandera, Josef (referee) ; Hejátková, Edita (advisor)
The beginning of this thesis contains an overview of properties of the insulators, and description of insulators that were used for in depth research of surface breakdown in vacuum. Furthermore, this work focuses on mechanisms of an electric breakdown initiation at the interface of the solid insulator and surrounding low pressure gas. Multiple methods for measurements of dielectric strength are examined. The experimental part describes the measurements performed in the vacuum chamber. The results of these measurements are then analysed. In conclusion, used insulators are compared and suggestions for further work are given.
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Synergic effects of multistress ageing of electroinsulating materials
Novák, Lukáš ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
Submitted work deals with monitoring impact of thermal and electric ageing on the dielectric properties of insulating material NKN 0887. In the course of the experiment five sets of dielectric insulating materials were aged. The voltage range has been set from 1,5 kV till 2,2 kV and temperatures were 23 °C and 200 °C. The capacity and loss factor has been directly measured by RLC meter Agilent with attached electrode system. The electrode system operates on the principle of a plate capacitor. The values of relative permittivity and loss number has been calculated from values of capacity and loss factor. For easier confrontation has been frequency dependences of these values plotted in a chart. The Cole-Cole diagrams has been created and factors of Havriliak-Negami function has been calculated. Data has been compared with each other and the effect of ageing factors has been deduced.
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