Evaluation of Uncertainty in the Measurement of Environmental Electromagnetic Fields

With regard to Non-ionising radiation protection, the relationship between human exposure to electromagnetic fields and health is controversial. Electromagnetic fields have become omnipresent in the daily environment. This paper assesses the problem of how to compare a measurement result with a limit fixed by the standard for human exposure to electric, magnetic and electromagnetic fields (0 Hz-300 GHz). The purpose of the paper is an appropriate representation of the basic information about evaluation of measurement uncertainty

Survey of ELF magnetic field levels in households near overhead power lines in Serbia

During the last eight years, VINCA Institute-Radiation and Environmental Protection Laboratory has performed environmental spot broadband measurements of extremely low frequency (ELF-50 Hz) electric and magnetic fields and RF (100 kHz-3 GHz) electromagnetic fields in over 35 municipalities in Serbia. These investigations were motivated by the local population requesting information about levels of general public exposure to time-varying electric and magnetic fields in living spaces. This paper presents a summary of values measured in households under overhead power lines. These measurements will be useful in determining the exposure levels of the general public, which in turn determines whether the exposure levels are within reference levels recommended by International Commission on Non-Ionizing Radiation Protection (ICNIRP) Guidelines. It has turned out that measured values are far below the recommended safe levels

Investigation of the optimal method for improvement of the protective characteristics of gas-filled surge arresters - With/without the built-in radioactive sources

This paper presents an alternative approach aimed toward improvement of protective characteristics of gas-filled surge arresters (GFSA). Although so far GFSA with built-in radioactive sources proved to have superior protective characteristics, environmental concerns often challenge functional benefits. Experimental results show that a hollow cathode used in GFSA (no radioactive sources), offers significant improvement of protective characteristics as compared to classical designs. A number of theoretical predictions and conclusions are confirmed experimentally

The influence of ideality factor on fill factor and efficiency of solar cells

The most important output characteristics of solar cells, fill factor and efficiency strongly depend on fundamental physical properties of semiconductor materials, such as mobility. lifetime of charge carriers, diffusion length, as well as on the type of transport processes in the device. Ideality factor is considered the most direct indicator of the dependence of output characteristics of solar cells on the electrical transport properties of the cell, that is junction. The results obtained by investigating the influence of ideality factor values on the quality of solar cell as photovoltaic generator are presented in this paper. Since fill factor and efficiency are main indicators of solar cells quality, better understanding of the physical processes leading to their decrease with the increase of the ideality factor is crucial for optimization of the input parameters, and at the same time for obtaining high quality solar cells.Trends in Advanced Materials and Processes, 3rd Yugoslov-Materials-Research-Society Conference, Sep 20-24, 1999, Herceg Novi, Yugoslavi

The model law for SF6 insulated systems

The variation of probability of the electrical breakdown of gases as a result of varying the interelectrode gap value is considered. The relevant analytical expressions have been obtained by treating the electrical discharge of gases as avalanche processes in real space and, in the sense of Markov processes, in the probability space. Parameters of the theoretical model are determined experimentally, while the whole model is experimentally verified. A rather good agreement between the results obtained experimentally and those anticipated theoretically is achieved for the surface change by a factor of ten concerning and also for the interelectrode gap change by the same factor. The experiments were carried out with the gas SF6. The absolute pressure was varied from 0.5 to 7 bars.14th IEEE International Pulsed Power Conference, Jun 15-18, 2003, Dallas, T

The new method of determining characteristics of elements for overvoltage protection of low-voltage system

This paper presents an innovative method for an efficient characterization of relevant characteristics of nonlinear overvoltage protection elements in low-voltage applications. Standard measuring equipment was modified to enable an efficient and repeatable experimental procedure in order to investigate characteristics of overvoltage diodes and varistors, in particular volt-ampere characteristic, volt-ohm characteristic, coefficient of nonlinearity, and dissipating energy. Furthermore, the pseudoempiric method using the area law has been developed to determine a pulse characteristic of a gas-filled surge arresters (GFSA). An innovative aging estimate algorithm was additionally used. The justification of the suggested method on commercial nonlinear overvoltage components was checked. Its protective characteristics were examined by both the classical approach and the new suggested method. The obtained results from both methods showed minimal discrepancies

Temperature stability of components for overvoltage protection of low-voltage systems

In this paper, we present temperature stability investigations of different overvoltage protection components employed in low-voltage applications. The following components have been examined: transient suppresser diodes, metal-oxide varistors (MOVs), gas-filled surge arresters (GFSAs), and polycarbonate capacitors. The aim of the research presented here is to identify the effectiveness of the overvoltage protection as a function of temperature. Experimental results,show that GFSAs have rather stabile operational characteristics in a wide temperature range (from -90degreesC to +210degreesC). As for MOVs they exhibit certain improvement of their protective characteristics at higher temperatures. Experimental results are backed tip by I theoretical explanations

Radioactive reliability of gas filled surge arresters

The goal of this paper is to determine use of gas filled surge arresters (GFSA) with a built-in radioactive sources in radiative environment. Furthermore, a pseudoempiric method has been developed to determine the GFSA pulse shape characteristics. These results are considered relevant for the use of this component in both military applications and space technology

Radioactive reliability of programmable memories

In this study, we examine the reliability of erasable programmable read only memory (EPROM) and electrically erasable programmable read only memory (EEPROM) components under the influence of gamma radiation. This problem has significance in military industry and space technology Total dose results are presented for the JL 27C512D EPROM and 28C64C EEPROM components. There is evidence that EPROM components have better radioactive reliability than EEPROM components. Also, the changes to the EPROM are reversible, and after erasing and reprogramming all EPROM components are functional. On the other hand, changes to the EEPROM are irreversible, and under the influence of gamma radiation, all EEPROM components became permanently nonfunctional. The obtained results are analyzed and explained via the interaction of gamma radiation with oxide layers

Extraction of parameters from I-V data for nonideal photodetectors: A comparative study

Parameters that characterize semiconductor devices are often determined with difficulty, and their values very frequently depend on the method used for measurements and analysis. The extraction of diode parameters from the obtained I-V measurements could be complicated by their dependence on the voltage and the presence of series resistance. Therefore, an interpretation of the experimental I-V data must be very carefully made. In this paper, some methods for obtaining diode parameters such as saturation current, ideality factor and series resistance are presented. An evaluation of these methods based on their application for the extraction of the relevant parameters of photodiodes is also performed. Some of the methods that produce reliable and reproducible results are evaluated based on the experimentally obtained results, and in the view of the complexity of the used methods and their limitations.Current Research in Advanced Materials and Processes, 6th Conference of the Yugoslav-Materials-Research-Society, Sep 13-17, 2004, Herceg Novi, Montenegr