The article presents the results of research concerning electromagnetic (EM) field emitted by rocks during the process of their destruction. The paper describes a measuring stand designed for subjecting rock samples to axial crushing. During the destruction of rock samples, both components of the electromagnetic field emitted by the rock were recorded. The paper presents the results of research on hard coal samples, presenting the obtained time domain waveforms and frequency spectrum of the emitted EM field components. Further potential uses of tests concerned with EM emitted by rocks are determined. Applications registering EM field in mine environments may provide an early mine collapse warnings.
This article presents the design of an innovative receiver capable of identifying electric and magnetic components of electromagnetic fields. The receiver senses and records electromagnetic disturbances generated as mine tunnels collapse. It offers excellent operating specification and the ability to sense and log magnetic and electrical component strength values in real time. The paper analyzes the data obtained with the use of a system installed in a working mine and attempts to determine hazards resulting from increased rock stress levels that, cause spontaneous EM emissions.
This paper analyses the function of an innovative integrated receiver for the measurement of electromagnetic field emissions. The autonomous receiver measures and registers the elevated emission levels of both components of the EM field originating from rocks subjected to increased mechanical stress. The receiver’s sensitivity of 60 µV/m, its dynamic range of 98 dB, and its impulse response of 0.23 V/µs were determined in laboratory conditions. Real EM field signals from hard coal samples subjected to crushing force were recorded using an autonomous receiver. The observed and recorded results confirm that the receiver operates in the full range of amplitudes of the EM field signal emitted from the rock. The results determine the band of characteristic signals for EM field emission from hard coal. The system created on the basis of autonomous EM receivers can support the existing seismic safety systems in real mine conditions by predicting the possibility of mine collapse hazards.
The article presents the issues regarding correct design of power circuits in multi-module electronic devices. At present, in more and more distributed power networks, DC-DC insulated galvanic converters are used. The high level of electromagnetic disturbances, both radiated and conductive, consist the key problem. The results of investigations of radiated and conductive disturbances emission of low impulse power supply developed on the basis of the guidelines contained in the article are presented. Streszczenie. Przedstawiono zasady poprawnego projektowania układów zasiania w wielomodułowych urządzeniach elektronicznych. Głównym problemem jest tu wysoki poziom zaburzeń promieniowanych i przewodzonych. Przedstawiono konstrukcję zasilacza impulsowego dla którego zmierzono poziomy zaburzeń elektromagnetycznych promieniowanych i przewodzonych (Kompatybilność elektromagnetyczna w systemach zasilania rozproszonego).
The article presents a new research apparatus for measuring the electromagnetic activity of landslides. The basic element of the apparatus is a highly sensitive underground receiver of the magnetic component of the EM field. Such a receiver inserted to the full depth of a landslide well records the levels of magnetic field amplitude at a given depth. Anomalous levels of the magnetic component indicate the existence of landslide slip planes. Combining several receivers into a measurement system will enable continuous monitoring of landslide activity. The article presents examples of studies using the discussed apparatus, which were carried out on real landslides.
The paper presents the results of grid power quality tests and wide frequency electromagnetic radiation level tests to which home power networks with photovoltaic systems have been subjected. The said results are meaningful from the point of view of safety and compatibility of electrical devices and the power supply system they are connected to. The tests covered stability of phase voltage and its frequency, harmonic level flicker, as well as RF radiated and emission levels. The measurements performed provide an answer to the question concerning the level of compliance of randomly selected home-installed PV systems with applicable recommendations and regulations concerning electromagnetic compatibility. The ability to meet the applicable standards translates into the health and safety of building inhabitants, which is the ultimate goal. Legal regulations concerning electromagnetic compatibility of renewable energy sources are consistent throughout the entire European Union.
The paper analyzes the operation of innovative composite measurement instrumentation for spontaneous electromagnetic emission. The designed receiver measures and records both components of the EM field emitted by rocks subjected to increased mechanical stress. The range of signals transmitted by the receiver system and its dynamics were determined. A receiver was used to observe electromagnetic signals generated during a hard coal sample crushing in laboratory conditions. Test results confirmed the high dynamic range of the system at 98 dB and the ability to observe signals over a range of frequencies up to 50 kHz. The experimental results confirm the signal bandwidth characteristic of coal mine EM field emission obtained in earlier studies. The constructed autonomous receiver can be used in mine workings as a complementary warning system for emerging mine hazards.
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