Stanoveni parametru soustroji, problematika mereni momentu setrvacnosti a torznich kmitu pomoci pocitace.

This thesis gives a general overview of methods of identification of parameters of electrical rotary machines. The work is especially focused on the design of experiments based on the PC Lab card. For these experiments, the software for data mining and data processing has been created. One of the goals was also the overview and application of methods for determination of the moment of inertia. This magnitude is not an electrical one. However, it is very important for electrical rotary machines. Due to this fact, a whole chapter is devoted to the description of the methods of determining the moment of inertia. These methods are focused on rotary bodies, however some of the methods mentioned can also be used for bodies of general shape. The mathematical model of asynchronous machine has been created. This model has been used for the simulation of transient phenomena of the whole machine unit. This model was filled by equations for solving of torsional vibration. The modelled results and characteristics have been verified by practical measurement in the laboratory of electrical machines.Available from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Moznosti prevence a screeningu nadorovych onemocneni v praxi praktickeho lekare.

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Measurement of the Switching Force without Force Sensor

At the railways, some parts of the a high speed corridor are being finished at present. In these corridors, trains can reach the speed of up to 160 km per hour. Consequently, the demand on switch point machine computer diagnostics has arisen. This paper present the way how it is possible to realize this demand in a very cheap manner and only with a small intervention into the existing connection of the interclocking system

Acceleration sensor based on the ferraris principle for rotary drives

During various transient phenomena of an asynchronous machine, oscillations of mechanical characteristics (speed, torque) of the machine occur very frequently. Very fast oscillations of speed of the electric drive may be detected by using a speed-voltage generator or incremental sensors, however, the precision is not high, or the requirements placed on the measuring instruments are strong. The submission offers a possibility of how to exploit the advantages of the accelerometer with permanent magnets for determining these oscillations. The requirements on the measuring chain are also substantially lower

Parallel winding of a synchronous generator

The paper deals with the design of seven times parallel synchronous generator winding. The parallel winding is not commonly used for synchronous generators because it could be a possible source of difficulties, especially compensatory currents. The paper mentions the design, simulations, manufacturing and results of a measurement performed in a power plant

Analytical Method for Compensation Choke Geometry Optimization to Minimize Losses

The article presents an analytical method for optimizing the geometry of the magnetic core of a three-phase compensation choke. The method describes the process of identification the fringing magnetic fields and the corresponding magnetic reluctances of the magnetic core, the flux density calculation even in the case of the core supersaturation and the total losses estimation. It shows finding the trade-off between the size/weight of the inductor and the magnetic core with respect to the overall losses and demonstrates their minimization. The mathematical model for the flux’s identification is based on a standard iterative calculation using the analogy to electrical circuits but includes a new approach to the calculation of fringing magnetic fields caused by the air gapped magnetic core. The presented method is verified by the finite element method (FEM) using the engineering calculation software ANSYS

Design, construction and calibration of the current sensor for medium frequency high-power electronic applications

The paper discusses design methodology, constructional alternatives and calibration procedure of current sensor suited for high-power semiconductor systems operated at medium switching frequencies (industrial contact and contactless power chargers). Even there are several types of the sensor on the market, for medium frequency operation they usually exhibit problems with measured signal and its postprocessing. Proposed sensor is designed for a current up to 200 A and 120 kHz and is based on current transformer principle. Design procedure is focused on winding analyses and its impact on operational characteristics. In order to verify proper choice of magnetic core and windings distribution, finite element analysis have been provided to verify magnetization and saturation of sensor core. Consequently, the internal structure of the sensor and its construction is being described, while it is considered that the sensor is equipped with an electronic unit in a common housing. The electronic transducer evaluates the measured data and produces the digital output signals, which are easy to transfer even to a long distance. Prototype of constructed sensor has been undertaken to experimental measurements for given frequency range in order to evaluate quality factors and accuracy. At the end of the paper, the required process of calibration was provided through the evaluation of the algorithm required by digital logic of the sensor.The paper discusses design methodology, constructional alternatives and calibration procedure of current sensor suited for high-power semiconductor systems operated at medium switching frequencies (industrial contact and contactless power chargers). Even there are several types of the sensor on the market, for medium frequency operation they usually exhibit problems with measured signal and its postprocessing. Proposed sensor is designed for a current up to 200 A and 120 kHz and is based on current transformer principle. Design procedure is focused on winding analyses and its impact on operational characteristics. In order to verify proper choice of magnetic core and windings distribution, finite element analysis have been provided to verify magnetization and saturation of sensor core. Consequently, the internal structure of the sensor and its construction is being described, while it is considered that the sensor is equipped with an electronic unit in a common housing. The electronic transducer evaluates the measured data and produces the digital output signals, which are easy to transfer even to a long distance. Prototype of constructed sensor has been undertaken to experimental measurements for given frequency range in order to evaluate quality factors and accuracy. At the end of the paper, the required process of calibration was provided through the evaluation of the algorithm required by digital logic of the sensor

Complex design method of filtration station considering harmonic components

The paper deals with a new methodology for calculating the filter parameters. The basis is respect for the fact that the real filter current consists of other harmonic components, which filter is tuned. The proposed methodology was used to design filters for traction substation 25 kV/50 Hz. The operation of the locomotives in the AC supply systems of 25 kV/50 Hz leads to a rising of higher order harmonic currents. Due to the 1-phase supply system, these are mainly the 3rd and 5th harmonics. By simulation and subsequent measurement of the proposed traction power station filters the proposed methodology was verified. Thus, the filter design can also be used for filter compensating stations of the standard 3-phase distribution network. The described method presents an optimal filter design without unnecessary oversizing. This fact reduces the size and cost of the filter. It is shown that it is possible to design a filter that meets the requirements for power quality under extreme load and to minimise distortion of line voltage

Current sensor with low inductance

This paper deals with design of current sensor introducing low inductance. The sensor is designed for a current up to 500 A and 120 kHz. Since the market offers several types of sensors suitable for the targeted application, they usually have problems with measured signal postprocessing. This paper describes the principle of operation and includes simulation results and measurement made on the laboratory prototype of the proposed sensor

Experimental verification of the finite element analysis of an induction machine with implemented static eccentricity fault

The paper deals with the experimental verification of vibration frequency spectra of squirrel-cage induction machine having implemented static eccentricity fault. The measured data are compared to the theoretical presumptions and the transient finite element analysis of the measured machine. Measurement and finite element model are carried out for the machine in a perfect technical condition as well and those specify the reference point for the faulty machine