Abstract
An interesting phenomenon was noticed in some cases by workers operating with cranes in electromagnetic field of broadcasting antennas. They experienced electrical shock or burning pain at distances of kilometers away from powerful transmitters because cranes act as unintentional receiving antennas. The solution to this problem depends on dimensions and positioning of the crane structure, electromagnetic field strength at the site, frequency, and directional characteristic of the transmitting antenna. Electromagnetic interference between such structures is analyzed in this paper. Computational results for the induced currents and voltages in crane, treated as wire antenna problem, are determined using integrodifferential equations for the current along conductive structure, satisfying boundary condition for the electric field. Point matching method as the Method of Moments (MoM) is applied for solving these equations and polynomial approximation of the current is used. Results are presented for different crane structures and possible solutions to this problem are given.
Highlights
When considering interference between natural electromagnetic sources of disturbances and various man-made objects, the key issues are electromagnetic field strength, amplitudes of voltages and currents, electrical properties of the medium, dimensions and positioning of the structure, distances, and frequency
An interesting phenomenon was noticed in some cases by workers operating with cranes in electromagnetic field of broadcasting antennas. They experienced electrical shock or burning pain at distances of kilometers away from powerful transmitters because cranes act as unintentional receiving antennas. The solution to this problem depends on dimensions and positioning of the crane structure, electromagnetic field strength at the site, frequency, and directional characteristic of the transmitting antenna
Large conductive structures permanently or temporarily positioned in electromagnetic field of powerful medium wave (MW) transmitters, if their dimensions are of the order of wavelength, might be dangerous for humans and equipment
Summary
When considering interference between natural electromagnetic sources of disturbances (terrestrial, as lightning discharges, or extraterrestrial, as cosmic radiation and solar wind) and various man-made objects (such as equipment, electronic devices, electric systems, power lines, communication and automation systems, and installations), the key issues are electromagnetic field strength, amplitudes of voltages and currents, electrical properties of the medium, dimensions and positioning of the structure, distances, and frequency. Finite ground conductivity has some influence on induced voltages and currents, so it could be considered using the same procedure as in this paper, but the solution to this problem is what matters. These electromagnetic interference (EMI) problems were rarely noticed and described just in a few papers [1,2,3,4,5,6,7]. Large conductive structures permanently or temporarily positioned in electromagnetic field of powerful medium wave (MW) transmitters, if their dimensions are of the order of wavelength, might be dangerous for humans and equipment. AM carrier frequencies are assigned to stations in the frequency range from 531 to 1611 kHz, and, just in Europe, there are still more than a hundred of them with power ranging from 1 kW to 1 MW [8], depending on the targeted area (local, regional, or international)
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