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This article deals with the process of the experimental induction melting of aluminium oxide in so called cold crucible (CC). The experiment took place in a couple of steps, that were needed for a successful realisation of the melting. The first step was the designing of suitable parameters of the cold crucible regarding the depth of penetration of the eddy currents into the melted aluminium oxide...
This paper describes the analysis of power generating units and their implementation, these are located within the technological centre in Ostrava-Vitkovice. Further issues concerned in this paper deal with digital simulation using computer model created using the EMTP — ATP software to evaluate particular process courses that may occur on the power inverter installed in the technological centre....
The aim of this work is the evaluation of the data obtained from experimental PV solar system performance. 500 Wp PV system is installed on the roof of Faculty of Electrical Engineering and Information Technology of Slovak University of Technology in Bratislava, Slovakia. In addition the obtained results are compared with the PVGIS simulation. A brief summary of components and construction parts of...
This paper deals with analysis of induction motor fed by non-harmonic voltage source. The losses are determined based on direct method for analysis of motor efficiency. The method is presented for fractional losses analysis with consideration harmonics generated by PMW. The introduced method earmarks the fundamental harmonic components of electrical magnitudes for comparison purposes of different...
This paper is focused on an analysis of mutual influence between the circuits of different voltage level located on the same pylon. The significant consequence of these mutual couplings between all conductors including earth wires is a voltage induced into conductors which results in current asymmetry not only during a specific operations but also during standard operations. In the case, that some...
In this paper, the thermal ageing of pressboard impregnated with two kinds of insulation liquids is studied by means of frequency domain spectroscopy which involves the measurement of real and imaginary part of complex permittivity as function of frequency. The magnetic nanofluid was composed by mineral transformer oil as carrier liquid, nanoparticles of magnetite and surfactant. The thermal aging...
The basic formulas for analytical determination of the earthing system resistance are given by the European standard EN 50522:2010 [1] in its annex J. As these formulas are rather vague about how to determine the earthing system resistance for more complicated shapes of earthing systems consisting of more basic earthing electrodes (e.g. strip, rod, ring), this formulas are cited in the Czech Republic's...
This paper deals with theme of measuring of photobiological safety. For evaluating of photobiological safety is important determination of visual angle of source. Paper is describing effect of visual angle change on measured data. Visual angle was changed by changing of measuring distance and by changing of field stop diameter. All measurement was realized on double monochromator spectroradiometer.
The induction machine operated as generator can be a very valuable alternative to the synchronous machines. Mostly in applications with lower nominal power ratings. In this case it can be more cost effective. Disadvantageous is a fact that induction machine cannot generate a reactive power and even more it is a permanent consumer of the reactive power. This paper strives to analyze possible application...
The approach of this paper it is about voltage conformity delivered to the final customer, on electricity distribution networks. Have obtained physical and electrical characteristics information from the network coming from the database of the electricity company. The study presents the process of voltages estimation in primary and secondary circuits wich estimation of indicators of voltage violation...
The article deals with the operation of biogas stations, especially in terms of power supply to a 22kV distribution grid. The article includes a draft model the objective of which is to simulate power supply to the aforementioned 22kV grid. The main objective of the model is to verify the stability of power supply. Furthermore, this model will be used for automatic analysis of the data obtained through...
The paper deals with an analysis of features of on-off controllers. It was assumed that the control quality can be described by three distinctive indexes: the period, the amplitude and the mean value of the controlled signal in the steady state. The on-off controller with positive hysteresis was a basic form of the controller that was analyzed. To eliminate the disadvantages of this basic form the...
Progress in efficiency improvement has been main a matter in grid tie inverters. The employment of multilevel inverters in energy conversion promises a better power quality and lower switching losses than ordinary two-level inverters even in low voltage grid. This paper presents the implementation of several control schemes (Vector Oriented Control, Hysteresis Control) and modulation techniques (Pulse-width...
This article has task to inform a reader of uncertainties of measurement in laboratory of light, especially in integrating sphere. In the first part there are mathematical descriptions of different types of uncertainties, including the methodology for their determination. The second part is focused on detailed description of particular standard uncertainties for measurement of the luminous flux in...
This paper deals with comparison of measuring and simulation of electromagnetic field shielding effectiveness. The experiment and simulations were focused on measuring and simulation of shielding effectiveness in the range of high frequencies from 0.9 GHz to 5 GHz. The measured object was a brick wall with a thickness 50 cm. Size of brick wall were 2×2 m. Measurement was preformed according IEEE 299–2006...
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