Field components of the electromagnetic environment related to the presence of the overhead transmission lines MARILENA UNGUREANU Dept. of Power Systems University “Politehnica” of Bucharest 313 Splaiul Independentei, sector 6, Bucharest ROMANIA ADRIAN C-TIN RUSU C.N.T. E.E Transelectrica Bucharest ROMANIA ILEANA BARAN Dept. of Power Systems University “Politehnica” of Bucharest 313 Splaiul Independentei, sector 6, Bucharest ROMANIA marilena_ungureanu@yahoo.com Abstract: - This paper presents some important components of the electromagnetic environment associated with the presence of overhead power lines, taking into account different frequency ranges which are identified during operation regimes in the electromagnetic field in vicinity of overhead power lines. The interferences in the range of RI waves can be significant. RI interference usually comes from incidental radio frequency emitters which include overhead power lines. The rich harmonic content of some electronic devices (computers, television sets) means that they can interfere over a very broad spectrum. This paper points out the influence of the dissymmetry of the voltage system upon the magnitude of the intensity of the electric field. Key-Words: electric field, magnetic field, disturbances, interferences, induced voltages induced current, corona discharge, crossed over lines 1. Electromagnetic environment Electromagnetic environment (EME), a component of the natural environment, represents the totality of the electromagnetic phenomena that coexist in a certain place at a certain time. The EME includes useful as well as disturbing electromagnetic signals along with propagation parameters like speed, attenuation and reflection coefficients which are depending on local material properties as dielectric permittivity, magnetic permeability or electric conductivity. All these draw up a parameter set of the environment that could vary with time. The EME can be characterized by: - active electromagnetic emission sources: artificial sources (electrical equipments, industrial installations) or natural sources (atmospheric phenomena, cosmic radiations); - measurable values (currents, potentials, the intensity of the electric, magnetic or electromagnetic field). The effects generated by the electrical installations can be classified as: quantifiable effects, evaluated by measurable physical values and non-quantifiable effects manly evaluated by direct perception (fig.1). The electromagnetic pollution (electromagnetic impact) is referring to all the aspects associated with presence of the electromagnetic fields of different frequencies in the vicinity of the electric power lines or substations. Their intensity becomes more important as the rated voltage is higher. The most difficult problem is to find out the value of the induced current in living organisms immersed in an electromagnetic field and the induced voltages from inductive or capacitive coupling in different metallic structures which could cause annoying contact currents or even deadly currents for the living or electrical equipment dysfunctions. For its quantification, is necessary to use the concept of the class of emplacement having the meaning of an ensemble of emplacement areas with similarities from point of view of nature and density of the electric or electronic equipment, the installing conditions or electromagnetic disturbances. The severity level characterizes each class for different kind of electromagnetic disturbances witch accede to the equipments/ systems by different ports of them. 2. Values referring to electromagnetic impact and limitations 2.1 Values referring to impact a. Frequency ranges of electromagnetic emissions - in the SLF range, (30 to 3000) Hz the power frequency (50/60 Hz) electric and magnetic field and field harmonics emitted in the vicinity of power lines and electric substations in normal operation conditions WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT Marilena Ungureanu, Adrian C-Tin Rusu, and Ileana Baran ISSN: 1790-5079 149 Issue 9, Volume 3, September 2007