[en] This paper presents a simple computational method for predicting the magnetic field above ground, generated by an underground three-phase pipe-type cable. In the computation, an approximation is made to simplify the problem a Fourier series technique and an iterative procedure are employed to handle the nonlinear B-H characteristic of the steel pipe. To validate the computational method, measurements were made and the numerical results are compared with the measurement data. Also, data of magnetic fields generated by the pipe type cable are compared with those due to the cable in absence of the pipe. The advantages and disadvantages of this simple method are discussed

[en] The paper analyses the signal propagation behaviour and hence assesses the data transmission potentials of the 330kv single circuit overhead transmission lines. From the data collected from the NEPA Headquarters, the basic characteristic admittance matrix and impedance matrix were derived and used to obtain the high frequency parameters. These parameters reveal the propagation characteristics behaviour of the lines. For the study of the load cycle effects, the peculiarities of the meteorological conditions of the regions these lines are run need to be considered. NEPA classifies the Nation (Nigeria) into two zones: Zone A (South) and Zone B (North). The various effects on the lines due to loading given the peculiar atmospheric conditions in these zones were studied. All results obtained were exhaustively discussed: Conclusions were drawn and specific recommendation was made on the suitability of the 330kv lines for signal (data) transmission. (author)

[en] It is possible to use designs of overhead high voltage electricity lines which minimise environmental damage. The designs proposed from studies at St. Petersburg Technical University are outlined and the benefits given. (author)

[en] The magnitude of electric and magnetic fields around a high voltage three-phase transmission line was studied. A three-phase transmission circuit with parallel conductors produces rotating elliptic electric and magnetic fields. This study investigated the optimum arrangement of the phase conductors to minimize the maximum value of the magnetic flux density and to minimize the intensity of the resultant electric field. Two different types of high voltage double circuit transmission lines of 400 kV were considered. The optimum arrangement of the phase conductors was determined. It was concluded that the optimum arrangement can be easily applied to already constructed high voltage transmission lines by properly interchanging the phase conductors at the substations. 10 refs., 1 tab., 4 figs

[en] The propagation of electromagnetic waves through a (homogeneous) plasma (slab) in a sheared magnetic field is dealt with by adopting a frame of reference which follows the local direction of the magnetic field. The choice of such a local reference frame is particularly appropriate in order to obtain both the dispersion relation and the polarization of the two eigenmodes relevant to the radiative transfer at an arbitrary angle with respect to the magnetic field, and, in particular, so that no linear mode coupling occurs in the limit of uniform shear. The dispersion relation thus obtained is discussed in detail and the conditions for which the true eigenmodes of a sheared plasma can be identified with the extraordinary and ordinary mode in the absence of shear are assessed. Effects due to the non-uniformity of the magnetic shear are also considered in a quasi-optical approximation and the consequent imaginary part of the refractive index is discussed in the context of the transport equation for the electromagnetic energy density. (author)

[en] A rigorous procedure is presented for the evaluation of the rectangular components of the electromagnetic field radiated by excited carrier channels on multiconductor overhead power lines above a lossy ground. The proposed full wave approach, based on the use of Hertz potentials, allows to carry out the high-frequency analysis of a spread spectrum transmission system. Field sources are the current traveling along the line, which are evaluated by means of an accurate line simulation model including the ground return parameters, obtained by removing the Carson quasi-static hypotheses. The frequency-spectra and the lateral profiles of the field components radiated from wire-to-ground and wire-to-wire channels on a three-conductor distribution line are computed in a frequency-range up to 20 MHz

No abstract available

[en] The concern about electromagnetic field (EMF) effects on human health has heightened public awareness of overhead transmission lines planning and operation. The objective of this paper is to study the effect of EMF constraints on optimal power generation scheduling. This study considers reducing EMF levels associated with critical transmission lines by redistributing the scheduled power generation, while maintaining the minimum operation cost as an objective. The EMF constraints are given in terms of control variables and fuzzy sets are utilized to model the tradeoff between minimizing the objective function and satisfying EMF constraints. Numerical results for the application of the proposed approach to test systems are discussed

[en] A study was conducted to examine ELF electric and magnetic fields (E- and B- fields) in the vicinity of ultrahigh voltage overhead power transmission lines and substations. Both the planar-type electric field probe and a multiturn loop field sensor were specially developed for measuring E- and B- fields three-dimensionally. The measurements were made at a 345 kV power substation and under overhead transmission lines. It was shown that E- and B- field distributions differed in the horizontal arrangement of conductors from the vertical arrangement of bundle conductors. The B- field strength around the substation and the overhead transmission lines was independent of the height above the ground in the range from 0.5 to 2 m. 7 refs., 1 tab., 10 figs

[en] In the paper the basic concept of the insulation co-ordination is presented. A special review is given to the experiences of the insulation co-ordination of the Macedonian 420 kV network. Some weakness in the concepts are noticed. Even though the standard IEC 71-2 is quiet specific, in many cases in additional survey is necessary for both economically and technically correct decision. The last part of the paper deals with these case. [Original)