Application of standard and modified Eh-Star test method for induction motor stray load losses and efficiency measurement

The aim of this paper is to present the application of one simple and accurate method for the measurement of stray load losses (additional load losses) in induction machines. That is the Eh-Star method given in the IEC 60034-2-1 standard. In this paper the theoretical background of the method and the measurement procedure have been explained. All measurements have been performed using modern measurement systems based on a personal computer, data acquisition cards and LabVIEW software. According to the measured results for the stray load losses, the efficiency of the induction motor has been calculated. The efficiency obtained has been compared with the IEC standard efficiency classes, in order to determine the efficiency class of the tested motor. Additionally, measurements have been performed using the modified Eh-Star method. The results obtained have been compared with those obtained using the Eh-Star method. The advantages and disadvantages of both methods have been analyzed in this paper

CALIBRATION OF AC INDUCTION MAGNETOMETER

The aim of this paper is to describe a procedure and experimental setup for calibration of AC induction magnetometer. The paper presents an overview of the previous research and results of measurement of magnetic flux density inside large-diameter multilayer solenoid. This solenoid is magnetising coil of the magnetometer. The paper also describes a system of five smaller coils of the magnetometer which are placed inside the large solenoid. Three small coils are pickup coils, accompanied with two compensation coils, of which one is an empty coil for magnetic field measurement. The experimental results of calibration of this coil system have been presented. A proper discussion of all the results presented has been also given in the paper

Construction and programming of the platform for spatial imaging with sensors

This study was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, and these results are parts of the Grant No. 451-03-68/2022-14/200132 with University of Kragujevac – Faculty of Technical Sciences in Čačak.In this paper, the construction solution and the method of programming the platform for spatial imaging with sensors are presented. The mechanical construction of the platform is described in detail, as well as the electrical components needed for movement of the sensor carrier in the horizontal plane. Movement is achieved by two stepper motors, and movement control is obtained by connecting the corresponding Arduino and LabVIEW programs. The movement of the carrier from the initial position, through four arbitrary points, until it is placed again in the initial position was realised. The paper provides relevant technical data about the platform, connection diagrams, parts of the program code and accompanying discussion.Publishe

ANALYSIS OF MEASUREMENT ERROR IN DIRECT AND TRANSFORMER-OPERATED MEASUREMENT SYSTEMS FOR ELECTRIC ENERGY AND MAXIMUM POWER MEASUREMENT

Analysis of error in measuring electric energy and maximum power within direct and half-indirect measurement system at the voltage of 0.4kV is presented in the paper. The analysis involved all the elements of the measurement system, i.e. calibration and testing of the transformer-operated and direct digital energy meters and measuring current transformers. This equipment was also used for measurements in the transformer substation aiming at error analysis at measurements made under the real conditions

HARMONIC ANALYSIS AND MODELLING OF MAGNETISATION PROCESS IN SOFT FERROMAGNETIC MATERIAL

The aim of this paper is to present a research of magnetic hysteresis loops of a toroidal ferromagnetic core made of electrical steel. The experimental results of induced voltage, magnetic induction and hysteresis loop obtained at different frequencies of the sinusoidal excitation magnetic field have been presented. The harmonic content of the induced voltage and magnetic induction have been calculated using Fast Fourier Transformation. Observed variation of higher harmonics with frequency has been correlated to the mechanism of magnetic domain walls damping. A variation of harmonics of the magnetic induction with the amplitude of the excitation magnetic field has been analysed and a proper mathematical model has been proposed. Furthermore, the influence of the triangularly shaped excitation magnetic field and the distorted shape excitation that produces sinusoidal induction on the shape of hysteresis loop and harmonic content of the induced voltage and the magnetic induction has been analysed and discussed

Integration of virtual instrumentation in marine electrical engineering education

This paper has been prepared within the framework of the ERASMUS+ CBHE project titled “Sustainable development of blue economies through higher ed-ucation and innovation in Western Balkan Countries - BLUEWBC”. Also, the research presented in this paper is supported by the Ministry of Education, Science and Technological Development of the RS, contract no. 451-03-68/2022-14/200132, which is implemented by the Faculty of Technical Sciences in Čačak - University of Kragujevac.Virtual instruments have wide application and they are used not only for measurements and control but also as an excellent tool in engineering education. They can be utilized in real and actual labor-atories. They present huge support for individual learning and distance learning. This paper presents an example of using virtual instruments in the education of future Electro Technical Officers, actually the present students enrolled in the study program of Marine Electrical Engineering at Faculty of Maritime Studies Kotor, University of Montenegro. With the aim of promoting practical exercises for the subject Ship's Measurements as a part of the undergraduate study of Marine Electrical Engineering, the paper proposes examples of laboratory exercises with belonging schemes of connection and experimental set up.Publishe

Short-circuit and load operation of single-phase transformer at low frequencies

© 2019, Wydawnictwo SIGMA-NOT. All rights reserved. The aim of this paper is to present experimental results on the short-circuit and load test of the single-phase transformer at low frequencies. The paper gives information on PC based measurement setup and presents the results of measurement of primary and secondary voltages and currents and electric power of the transformer. Also, a proper discussion of the results obtained is given in the paper

Verification of Bertotti's loss model for non-standard excitation

© 2019 Polish Academy of Sciences. All rights reserved. This paper focuses on the possibility to use the Bertotti loss theory to describe energy losses in a toroidal core made of grain-oriented steel sheet under non-standard excitation conditions. The temporal Hclas (t) and Hexc (t) dependences are computed using a simple numerical scheme, which may be easily implemented in a spreadsheet