Implementation of new equipment for the laboratory exercises – Testing of low-voltage electrical installations

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 Čačak.This paper presents the new equipment that is used for laboratory exercises in the subject of Electrical installations and lighting at the undergraduate academic and professional studies in the Faculty of Technical Sciences in Čačak. Multifunctional electrical installation safety testers for testing domestic and industrial electrical installations were presented. A demonstration board that provides simulation of different types of faults in electrical installations is also presented. As an illustrative example, the paper presents the procedure and results obtained during the realization of the exercise - Measurement of ground fault loop impedance in TT and TN earthing systems and checking the conditions for automatic disconnection of supply.Publishe

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

Correlation between Load Current and Temperature for a Power Cable Installed in a Vertical PVC Pipe

The heating of an ethylene-propylene rubber (EPR) insulated cable installed in a vertical polyvinyl chloride (PVC) pipe is analysed in this paper. In particular, this paper considers the heating of an EPR cable used to energize a submersible water pump and analyses the upper part of the well where the space between the EPR cable and the inner surface of the PVC pipe is filled with air. The temperatures of the cable’s surface are determined analytically, and then such temperature values are validated numerically by using the finite element method (FEM) in COMSOL. In addition to these calculations, experiments are performed on a physical model representing the part of the well between the static water level and the solid concrete cover of the well. The percentage deviation of the calculated values for the cable’s surface temperature from the measured ones at different load currents ranges from 1.47% to 4.63%. After the experimental validation of the calculated values for the cable’s surface temperature, an analytic expression (i.e. correlation) that defines the dependence of that temperature on the load current and the pipe’s inner surface temperature is derived. Finally, an analytic expression for the cable load current as a function of the cable’s surface temperature and the pipe’s inner surface temperature is also derived, which can be further used to determine the ampacity of any power cable for known service conditions.Publishe

Razvoj laboratorijskog sistema za merenje karakteristika fotonaponskotermičkog panela

The emissions of harmful gases into the atmosphere, air pollution and global warming can be greatly reduced by increasing the use of renewable energy sources such as solar energy to heat domestic hot water, space heating and generating electricity. This paper describes the systems of combined (hybrid) PV/T panels that can simultaneously generate both heat and electricity, as well as the characteristics of the PV/T panel. A prototype of the laboratory setting for the examination of these systems along with the used components is also shown. The temperature, fluid flow rate values, obtained heat and electric gain are also presented. Deficiencies and proposed changes in the laboratory setup and used equipment were laid out, in order to improve the accuracy of the measurements.Publishe

Artificial neural network model for predicting air pollution. Case study of the Moravica district, Serbia

© 2018 Technical University of Wroclaw. All rights reserved. An example of artificial neural network model for predicting air pollution has been presented. The research was conducted in Serbia, the Moravica District, on the territory of two municipalities (Lucani and Ivanjica) and the town Cacak. The level of air pollution was classified by a neural network model according to the input data: municipality, site, year, levels of soot, sulfur dioxide (SO2), nitrogen dioxide (NO2) and particulate matter. The model was evaluated using a lift chart and a root mean square error (RMSE) has been determined, whose value was 0.0635. A multilayer perceptron has also been created and trained with a back propagation algorithm. The neural network was tested with the data mining extensions (DMX) queries. The results have been obtained for air pollution based on new input data that can be used to predict the level of pollution in future if new measurements are carried out. A web-based application was designed for displaying the results