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Selected Problems of Diagnosis of Insulation Systems for Rotating Electrical Machines
Pavlík, Josef ; Radek,, Szabó (referee) ; Singule, Vladislav (referee) ; Hammer, Miloš (advisor)
This dissertation thesis deals with the measurement of insulation resistance for rotating electrical machines and polarization indices calculated from them. The first part contains a short theoretical introduction, methods of measurement and basic formulas for calculations. The second part discusses the results obtained in laboratory measurements in both the model and the real coil of high voltage machine. There are also elucidated some of the principles and causes of some phenomena with which the measurement of insulation resistance is encountered. The third part deals with the results of measurements on real machines. There are mainly discussed the dependences of insulation resistance and polarization index on the influences that occur in measurements such as temperature measured insulation, moisture in the insulation, but also the influence of measuring instruments on the measured values. It is also expressed how much these factors affect the measurement results. In addition, this part deals with some other influences that have a negative affect on the measurement of insulation resistance. There is processed a new methodology for measuring insulation resistence in the fourth part of this thesis. The need to develop a metodology of measuring is based on the needs of engineering practice, where is considerable inconsistency of measurement in the present time. Measurement, and often performed on the same machine, are not nowadays often comparable, because measurements are not met even the basic rules resulting from the findings of research and development, which were discovered in the last few decades. Measurement of insulation resistance in our nowdays methodology stagnated on the level of the seventies of 20th century. For this reason, we have developed a new methodology of measurement that takes into account all significant influences affecting the measurement. The purpose of the methodology is to ensure full repeatability and comparability of measurements not only on the same machine but on machines of the same type, in optimal cases, the machines of different types. There are the chapters "The objectives of the work" and "Conclusion" the part of the work. A very important chapter is "The contribution of thesis", which summarizes the original results of this work and results, the use of which is expected in engineering practice.
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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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Complex Analysis of Modal Properties of Rotating Electrical Machines
Donát, Martin ; Vlach, Radek (referee) ; Žiaran,, Stanislav (referee) ; Dušek, Daniel (advisor)
This dissertation thesis deals with the computational modelling of the dynamic response of the rotating electrical machine structure on the application of the magnetic forces. Apart from the dynamic response of the ideal symmetrical machine, the influence of the air gap eccentricity on the dynamics response is studied in this work. A basic type of the air gap eccentricity, which is caused by eccentric mounting of the rotor pack on the shaft of the rotor, is considered. The calculations the dependence of the magnetic forces on the time and a misalignment of the rotor pack are performed as first. The computational model of the magnetic field of the rotating electrical machine, which is based on solution of the electromagnetic coupled field analysis by finite element method, is used for this purpose. An analysis of the influence of the unbalanced magnetic pull and the stiffness of some parts of the machine on the modal properties of the machine is performed in the second part of this thesis. A third part of this thesis is focused on the calculation of the dynamic response of the machine during the steady state operation of the machine and the influence of the rotor pack misalignment on the dynamic response is studied. The obtained results showed that the tangential components of the magnetic forces, which act on the stator pack, excite significant torsional vibration of the stator. Besides the vibration of the stator of the machine, the influence of the rotor pack misalignment on the sound power of the machine, vibration of the rotor, loads of rotor bearings and air gap eccentricity is studied in this thesis.
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Design of computational algorithm of electric machine rotor with respect to stress-strain relationships and critical speed
Pařízek, Daniel ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
The Master's thesis deals with the mechanical design of electric machine rotor. Within the first two chapters of the practical part of the thesis two simplified computational models of the rotor (level 1 models) are compiled. Specifically, the model of flexible rotor mounted on rigid supports and model of rigid rotor mounted on flexible supports. The essence of these computational models lies in solvability using simple equations. Using these models can save time when constructing a pre-design of the rotor geometry. The following chapter is devoted to comparing different approaches to computational modeling of rotor using FEM. A predetermined preliminary design of a high-speed massive rotor is investigated. Computational models of different levels at stress-strain analysis and modal analysis are presented. It also includes a suggestion on how to proceed effectively in a given analysis.
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Design of computational algorithm of electric machine rotor with respect to stress-strain relationships and critical speed
Pařízek, Daniel ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
The Master's thesis deals with the mechanical design of electric machine rotor. Within the first two chapters of the practical part of the thesis two simplified computational models of the rotor (level 1 models) are compiled. Specifically, the model of flexible rotor mounted on rigid supports and model of rigid rotor mounted on flexible supports. The essence of these computational models lies in solvability using simple equations. Using these models can save time when constructing a pre-design of the rotor geometry. The following chapter is devoted to comparing different approaches to computational modeling of rotor using FEM. A predetermined preliminary design of a high-speed massive rotor is investigated. Computational models of different levels at stress-strain analysis and modal analysis are presented. It also includes a suggestion on how to proceed effectively in a given analysis.
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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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